INTERNATIONAL ATOMIC ENERGY AGENCY

NUCLEAR DATA SERVICESDOCUMENTATION SERIES OF THE IAEA NUCLEAR DATA SECTION

IAEA-NDS-208
January 2006

LEXFOR(EXFOR Compiler’s Manual)Compiled and edited byVictoria McLane
National Nuclear Data Center
Brookhaven National Laboratory, USA

Version January 2006
issued by the
IAEA Nuclear Data Section
on behalf of the
Nuclear Data Centers Network

Abstract: EXFOR is the exchange format for the transmission of experimental nuclear
reaction data between national and international nuclear data centers for the benefit ofnuclear data users in all countries. This report contains the compiler’s section of themanual, including physics definitions, background information and practical examples.
For a description of the format and coding rules see the EXFOR Systems Manual (IAEANDS-207).

Nuclear Data Section
International Atomic Energy Agency
P.O. Box 100
A-1400 Vienna
Austriae-mail: services@iaeand.iaea.org
fax: (43-1)26007
telephone: (43-1)2600-21710
web: http://www-nds.iaea.org

Note:The IAEA-NDS-reports should not be considered as formal publications. When a nuclear datalibrary is sent out by the IAEA Nuclear Data Section, it will be accompanied by an IAEA-NDSreport which should give the data user all necessary documentation on contents, format andorigin of the data library.
IAEA-NDS-reports are updated whenever there is additional information of relevance to theusers of the data library.
For citations care should be taken that credit is given to the author of the data library and/or to
the data center which issued the data library. The editor of the IAEA-NDS-report is usually not
the author of the data library.
Neither the originator of the data libraries nor the IAEA assume any liability for their correctness
or for any damages resulting from their use.

96/11

Citation guideline:
When quoting EXFOR data in a publication this should be done in the following way:
"A.B. Author et al.: Data file EXFOR-12345.002 dated 1980-04-05, compare J. Nucl. Phys.
12,345, (1979). EXFOR data retrieved from the IAEA Nuclear Data Section, Vienna."

LEXFORLEXFORINTRODUCTIONLEXFOR is the compiler’s section of the EXFOR Manual. The contents are arranged
similar to a lexicon in alphabetical order by subject heading. As distinct from the
EXFOR Systems Manual, LEXFOR includes information essential for compilers using
EXFOR, that is:• physical definitions of codes defined in the EXFOR Systems Manual and its
dictionaries,• physical background information required for preparing high-quality EXFORentries,• practical examples of how to use the EXFOR system,• other information that may be helpful to compilers.
The responsibility for updating LEXFOR is outlined in the Nuclear Reaction Data
Centers Manual, pages 2-3.
The LEXFOR subject headings are given at the top of each page. Each subject heading
starts with a new page for the sake of easier updating.

November 2005

1

LEXFOR(blank page)

November 2005

2

LEXFOR

Absorption
Definition: Absorption is the sum of all energetically possible interactions excluding elastic
and inelastic scattering.
REACTION Coding: ABS in REACTION SF3 (Process)Sum rules: Absorption = total minus scattering= nonelastic minus inelastic
Absorption is a sum cross section. It should only be used where two or more reactions areenergetically possible.
Examples of cases which are not coded under absorption:a.) The frequently so-called "hydrogen neutron absorption cross section" must clearly be
coded as (n,γ), because no other neutron-absorbing reaction besides (n, γ) is possible.
b.) The thermal "neutron absorption cross section" for gold should be coded as (n, γ), since
the energetically possible (n,p) and (Q FURVVVHFWLRQVDUHQHJOLJLEOHLQFRPSDULVRQZLWK
the measurement uncertainty of the (n, γ) cross section.
CaptureDefinition: A reaction in which the incident projectile is absorbed by the target nucleus
which then emits electromagnetic radiation.
REACTION coding: G in REACTION SF3 (Process)Neutron data
For fissile isotopes at thermal neutron energies below reaction (e.g., n,2n) thresholds:
Absorption = capture plus fission
Where absorption is, throughout an experimental data set, identical with the (n,γ) reaction, it
should be coded as (n,γ), see above. (See also Tautologies).
Alpha
Definition: Alpha is the radiative capture-to-fission cross section ratio, σn,γ /σn,f.
REACTION coding:(…(N,ABS),,ALF)1

at resonance energy: (…(N,ABS),,ALF,,RES)
See also Single-Level Resonance Parameters.
Disappearance Cross Section
The disappearance or removal2 cross section is defined as the cross section for all neutroninduced process producing no emergent neutron, that is (n,γ) + (n,p) + ... It differs from theabsorption cross section in that it does not include (n,2n), (n,np), etc.

1
2

The REACTION process code ABS is entered, since capture and fission are considered.
Note other meanings of "removal" in reactor physics and shielding physics.

November 2005

A.1

LEXFOR

Activation
Definition: Activation is the production of a radioactive residual nucleus as a result of areaction, which is determined by measuring a specific decay radiation emitted by the productnucleus.
The activation cross section is usually identified with one of the following:1.
a specific reaction, and, therefore, the data given should be coded under theappropriate reaction, e.g., (n,γ) or (p,n).
2.
the production of a specific radioactive nuclide, which may be produced by two or
more parallel reactions; this case may be coded as a production cross section, or as a sum of
the possible reactions, whichever is more appropriate. (See also, Production and Emission
Cross Sections, Sums).
Examples:a.) ((26-FE-58(N,N+P)25-MN-55,,SIG)+(26-FE-58(N,D)25-MN-57,,SIG))
b.) (26-FE-0(N,X)25-MN-57,,SIG)
The code ACTIV (activation) is entered under the information-identifier keyword METHOD.
The decay information used in the analysis of the data given should be specified under theappropriate keywords. (See Decay Data).
Compilers should take special care when coding activation cross sections to nuclei that havemetastable states to specify what has actually been measured. (See Isomeric States).

A.2

November 2005

LEXFOR

Analysis
The information-identifier keyword ANALYSIS is used to enter all relevant information on
how the experimental results have been analyzed to obtain the values (given under DATA)
that actually represent the result of the analysis. In particular, this keyword is used for
deduced data such as resonance parameters. If the basic data used for the analysis have also
been entered in EXFOR, a cross-reference to those sets should be given in the free text. If
important assumptions were made (e.g., negative resonances), these should be specified
either directly or by reference. For example, extrapolation and interpolation should be given
only with appropriate references. (See also Assumed Values, Dependent Data).
The keyword ANALYSIS should not be used for information on any analysis made on thedata set to obtain theoretical conclusions.3
Resonance parameters require an entry under ANALYSIS explaining how they have beenobtained. "Single level" or "multi-level" must be given in coded form, if known. A more
precise definition of the analysis in free text is desirable, at least in the form of a crossreference to the literature in which a description of the analysis can be found.
An energy step used in the analysis may be coded in the data table under the data heading
ANAL-STEP.
See also Corrections and EXFOR Manual Chapter 7: ANALYSIS.

3

Such information can be noted under the keyword ADD-RES.

November 2005

A.3

LEXFOR

Angle(See also Errors: Correlations, Differential Data).
Secondary-Particle Angle
The angle of a secondary particle with respect to the incident-projectile beam, or the angle
between a correlated particle pair, may be entered either as an angle in degrees (data units
ADEG) or as a cosine (data units NO-DIM). An angle given in degrees, minutes, and/or
seconds may be entered in two or three fields with the data heading repeated. See EXFOR
Manual, Chapter 4: Repetition of Data Headings.
For relativistic data, angular distributions may be given as a function of q, referred to as
momentum transfer, which is related to the center-of-mass angle by:
q = 2k sin(θ/2)
where k is center-of-mass momentum of the final system.
The momentum transfer is given in units of inverse length (e.g., 1/fermi). See Kerman4 formore detail.
Data headings:
ANG= angle in lab system
ANG-CM = angle in center-of-mass system
COS= cosine of angle in lab system
COS-CM = cosine of angle in center-of-mass systemq= momentum transfer
ANG-AZ = azimuthal angle
and other codes given in Dictionary 24 with the family flag G.
When two or more angles are considered (e.g., for angular correlations), the data headings
ANG1, ANG2, etc., are used. These are entered in the same order as the particles for which
the angles are given are entered in the particle considered subfield of the reaction string.
The angle at which the data are normalized, if different from the angle at which the data were
measured, may be given under the data heading ANG-NRM in the COMMON or DATA
section.
Angular Error and Resolution
Numerical values for the angular error or resolution may be entered in the COMMON or
DATA section using data headings from Dictionary 24 with the family code H, e.g.,
ANG-RSL, COS-ERR. Further information can be given in free text under the keyword
ERR-ANALYS. (See also Errors, Resolution).

4

A.K. Kerman, H. McManus, R.M. Thaler, Ann. Phys. 8, 551 (1959)

A.4

November 2005

LEXFOR

Assumed Values
Only values defined by the data specification keyword REACTION should be given in thedata table under the data heading DATA (and its derivatives). It is, however, often importantthat numerical values used for the derivation of the results also be entered into the data tablein coded form, i.e., values assumed by the author, including values taken from anothersource.
Reference cross sections used for normalization should be entered under the keyword
MONITOR. (See Standards).
Decay data should be entered under the keyword DECAY-DATA. (See Decay Data).
Assumed values for which a data-heading keyword exists should be coded under that data
heading in the COMMON or DATA sections, e.g., spin (SPIN J), resonance energy(ENí5(6).
All other assumed values for which a quantity code exists may be entered under the data
heading ASSUM in the COMMON or DATA section and defined in the BIB section under the
keyword ASSUMED. See EXFOR Manual Chapter 7: ASSUMED.
Following are some examples of data to be coded using the keyword ASSUMED.
a.) A cross section assumed for one of the elements in a compound to derive the crosssection for another.
b.) Cross sections assumed for an isotope in a natural isotopic mixture to derive a crosssection for another isotope in the mixture.
c.) A resonance width assumed in order to deduce other resonance parameters.
Example:BIB
ASSUMED…
ENDBIB
DATA
ANGLE
ADEG
…
ENDDATA

November 2005

(ASSUM,6-C-12(N,EL)6-C-12,,DA)

DATA
MB/SR

ASSUM
MB/SR

A.5

LEXFOR

Astrophysical S-factor(See also Thermonuclear Reaction Rate).
For non-resonant reactions between low-energy charged particles, the steepest dependence ofσ(E) is contained in the penetration factor for the Coulomb and angular momentum barrier.
For incident energies that are small compared to the height of these barriers, it is convenient
to factor out the energy dependence and an additional factor of 1/E. The cross section canthen be written:
in terms of the Coulomb parameter

σ (E) =S (E)
exp(−2πη )E

η = Z 1 Z 2 e 2 hν
wherev = relative velocity
Z1, Z2 = charge of incident ion and target, respectively

or in terms of the Gamow energy

σ (E) =[S (E)exp − βEE]

β = 0.98948 Z1Z2m1/2
whereE
Z1, Z2m= center-of-mass incident energy (MeV)= charge of incident ion and target, respectively= reduced mass of system:5 m = m1 m2/(m1 + m2)

REACTION Coding: (……,SIG,,SFC)
Units: a code from Dictionary 25 with the dimension E*B (e.g., B*EV).

S-factor as a function of angle.
Occasionally, the S-factor may be given as a function of angle: S(E,θ).
REACTION coding: (……DA,,SFC)
Units: a code from Dictionary 25 with the dimension EDA (e.g., B 0(965)

5

The actual mass must be used, not the mass number.

A.6

November 2005

LEXFOR

Author
The author(s) of a data set are entered under the information-identifier keyword AUTHOR, allnames between one set of parentheses and separated by a comma. The sequence of thenames should be the same as in the publication.
See EXFOR Manual Chapter 7: AUTHOR for coding format.
If a data set has several references with varying co-authors, all co-authors may be entered.
Some East-European authors spell their names, and, in particular, their initials differently
depending on whether they publish in their own language or in English. Gyulia (Hungarian)= Julius (English). Hristov (Bulgarian) = Christoph (English). If this is detected, the spellingin the author’s own language is preferred.
For the transliteration of Cyrillic names the following list should be used.
Ë
A

B

V

G

D

E

R

S

T

U

F

Kh

Ts

Zh

Z

I

Y

K

L

M

N

O

Ch

Sh

Shch ‘

Y

‘

E

Yu

Ya

P

This list had been made according to the ISO prescriptions, amended for computer usage withrespect to accents, with the exception that different systems are not allowed in parallel (as is
the case with the new ISO prescriptions). For instance the earlier transliterations Ju and Ja
are allowed in the new ISO as well as Yu and Ya.
This scheme corresponds to the official Russian transliteration scheme with the exception ofwhich is represented as ".
Asian Names: For Asian names the full name may be given with the family name given first:
Example: Li Xaodong

November 2005

A.7

LEXFOR

Average Resonance Parameters
For average resonance parameters, the energy range over which the data were averaged mustbe specified under the data headings EN-MIN and EN-MAX. When specified, the parametersl and J are given under the data headings MOMENTUM L and SPIN J (see under Quantum
Numbers).
1. Average Widths: The average of the resonance widths of a specified type in a specified
energy range.
REACTION Coding: quantity modifier AV in SF8
Units: a code from Dictionary 25 with the dimension E (e.g., KEV)
Example: (…(N,EL),,WID/RED,,AV) Averaged reduced neutron width
2. Average Level-Spacing: The average energy distance (D) between nearest-neighborcompound-nucleus resonances of total spin J caused by neutrons of orbital angularmomentum l.
If the J and l values of the resonance are not determined, then D is understood to indicate theobserved level spacing.
REACTION Coding: Parameter code D in SF6
Units: a code from Dictionary 25 with the dimension E (e.g., KEV)
Example:(…(N,0),,D)

Authors may apply statistical tests to evaluate the number of missed resonances.
information should be given under ANALYSIS.

This

3. Fermi-gas model parameters: See Nuclear Quantities.
4. Strength Functions: The strength function (S) is defined as the ratio of the average
reduced neutron width to the average level spacing for compound-nucleus resonances of
specified spin J and angular momentum l.
If l is known, but J is not known, the strength function given is defined as:
S1 = <gΓ1n> / (2l+1) D1
If J and l are not known, then S is understood to be the observed strength function.
REACTION Coding: parameter code STF in SF6
Units: NO-DIM
Example:REACTION…
DATA
EN-MINEV…
ENDDATA

A.8(……(N,EL),,STF)

EN-MAXEV…

MOMENTUM L
NO-DIM…

DATA
NO-DIM…

November 2005

LEXFOR

Center-of-Mass System
An indication that data are given in center-of-mass system (CMS) is given within the data
headings (not within the quantity codes). All quantities are understood to represent thelaboratory system, unless the data headings are modified by ‘-CM’, as for example:
EN-CM= energy of the center of mass of incident projectile and target.
E-CM= energy of the center of mass of two outgoing particles.
ANG-CM= angle between two emitted particles given in the CMSNUMBER-CM = heading for the coefficient number when the Legendre or cosine fit
refers to an angle given in the CMS1
DATA-CM= heading for data which are given in the CMS.
See also others given in Dictionary 24.
The compiler should use great care if converting the author’s data from the center-of-masssystem to the laboratory system, and should document such conversions in free text under the
keyword STATUS. The author’s original data should be retained.
Note: Only one representation (i.e., either laboratory or center-of-mass) for each parameter
may be coded as a variable in the data table. Other representation may be added under thedata heading MISC if considered desirable by the compiler. In case of doubt, thelaboratory system is preferred.

1

Independent of whether the fit has been made to an angular distribution in CMS or whether it has first been
made to an angular distribution in the laboratory system and then converted to CMS.

November 2005

C.1

LEXFOR

Chemical Compounds
In general, chemical compounds are specified under the keyword REACTION by combining acompound code, e.g., CMP, with the element number and symbol of its main component, e.g.,
26-FE-OXI for iron oxide, or 26-FE-CMP for any other iron compound. For a small
number of materials of particular importance for users of nuclear reaction data, special
compound codes are used. These are listed in Dictionary 9. (See also EXFOR Manual
Chapter 6: Coding of nuclides and compounds.
Example: 1-H-BNZ

for benzene (C6H6).

More detailed information on the compound is given under the keyword SAMPLE.
Three rules must be kept in mind:
1) A more specific code has priority over a more general code.
Examples:a) Zirconium hydrides are to be entered as 40-ZR-HYD, and not as 1-H-CMP or
40-ZR-CMP.
b) Water is to be coded as 1-H-WTR and not as 1-H-CMP.
2) For alloys (or other mixtures) the code CMP is combined with the element symbol of the
major component, usually the one named first. For chemical compounds the code CMP is
combined with the symbol of the primary element, usually the first one of the formula,for example, CaCO3 is coded as 20-CA-CMP, and not 6-C-CMP or 8-O-CMP.
3) If the compiler feels that two possible codes are equally relevant, the reaction
combination using the equal sign (tautology) may be used.
Examples:a) Ammonium-hydrocarbon((7-N-AMM,.....)=(1-H-CXX,....))b) Brass, if it contains 50% Cu and 50% Sn((29-CU-CMP,....)=(50-SN-CMP,....))
Typical data on compounds entered are low-energy neutron data, where chemical or
crystalline binding forces affect the neutron cross sections; an example is the total crosssection or thermal-scattering data of water. However, thermal scattering data for H2 must beentered under the isotope 1-H-1, supplemented by an entry under the keyword SAMPLE.
If, for example, the sample is a compound, e.g., PuO2, and, if the data given refer only to Pu,
then the data is entered under Pu.

C.2

October 2004

LEXFOR

Comments
Free text comments
The language of the free text comments is English, and clear English phrasing should be
used. (See Free Text, and EXFOR Manual Chapter 3: Free Text).
Unlimited free text comments are permitted with each information identifier keyword; however,the compiler should aim to be as concise as possible.
Information-Identifier keyword COMMENT
Free text comments may be entered under the keyword COMMENT, such as:•

Miscellaneous information that cannot logically be entered under other available
keywords.2•

Author’s statements about the data, e.g., whether they agree with theory or with other
data.

•

Compiler or evaluator comments (see also CRITIQUE, below).
Any information which does not originate with the author must be clearly labeled, e.g.,"Comment by the compiler:", and unambiguously separated from author’s comments, forexample, by including it between quotation marks.

Information-Identifier Keyword CRITIQUE
The keyword CRITIQUE may be used for free text comments on the quality of the data
entered, as given by the compiler or by an evaluator.3
The reference from which an evaluator’s comments are taken should be entered under the
keyword REL-REF. (See Reference).
Information-Identifier Keyword FLAGThe keyword FLAG is used to link free text comments in the BIB section with specific lines
in the DATA section. (See Flags).

2

Free text comments related to any other information-identifier keywords do not belong under the keyword
COMMENT. They should be entered under the appropriate keyword.
3
Such comments should be called to the attention of the author, when possible.

November 2005

C.3

LEXFOR

Corrections
All relevant information about corrections applied to the measured data to obtain the values
given under the heading DATA should be entered as free text information under the
information-identifier keyword CORRECTION.
Example: CORRECTION Corrected for multiple scattering.
This may include information on:• corrections that have been applied• corrections that have not been applied•corrections that are estimated to be negligible.
Corrections that are not mentioned by the author, but are regarded by the compiler as
relevant, may be entered under COMMENT (see Comments), where they must be clearlylabeled as compiler’s comments.
Errors contributed by the uncertainties of the corrections are entered under ERR-ANALYS(see Errors).
Consideration, depending on the compiler’s judgment: In general, the data resulting from thecorrections applied by the author are compiled. However, evaluators frequently re-assess olddata using improved corrections because they may have better knowledge on the theory of theexperiment than that which was available to the author at the time of the experiment. (Thismay concern items such as spectra shapes, detector-efficiency curves, etc.) In such cases, there-assessed data is useful information to the user of EXFOR data and should, therefore, becompiled. They would be labeled under STATUS with the code RNORM. The author’s
original values must be kept.
Compare: Status: Normalization.

C.4

October 2004

LEXFOR

Correlations (entry deleted)
Information moved to Differential Data.

Covariance
Definition
For a given set of experimental data points xi, there exists a set of errors nj. ∆xij are themagnitude of the uncertainties.
x1
x2
x3
…
xl

1
∆x11
∆x21
∆x31
…
∆xli

2
∆x12
∆x22
∆x32
…
∆xl2

3
∆x13
∆x23
∆x33
…
∆xl3

…
…
…
…
…

n
∆x1n
∆x2n
∆x3n
…
xln

The covariance matrix is a measure of these errors and the correlations between them. See
also Errors: Error Correlations.
CodingCovariance matrices, if given by the experimentalist, should be included, where possible,
either in structured form as free text under the keyword COVARIANCE or, for large
matrices, stored on a separate covariance file.
Information-Identifier Keyword COVARIANCE
Only non-zero matrix elements need be given.
Example:COVARIANCEVALUES GIVEN ONLY FOR ELEMENTS BELOW DIAGONAL OF SYMMETRIC MATRIX ON
SAME ENERGY GRID AS DATA.
1.0
0.98
1.0
0.90
0.97
1.0
0.70
0.82
0.93
1.0
0.54
0.68
0.83
0.96
1.0
0.64
0.75
0.85
0.92
0.95
1.0

The code COVAR is used under the keyword COVARIANCE to signal the existence of aseparate covariance file for that data set.
Example:COVARIANCE

November 2005

(COVAR) COMPLETE COVARIANCE MATRIX GIVEN IN SEPARATE
COVARIANCE FILE.

C.5

LEXFOR

Covariance (continued)
Covariance File
Data stored in the experimentalists’ format contains a header record that specifies the data set
number to which the matrix belongs, the covariance type, and the format.
Example:C10034002
C10034002
C10034002
D10034002
D10034002
D10034002
D10034002
D10034002
D10034002
E10034002

Values given only for elements below diagonal of symmetricmatrix on same energy grid as data format.
FORMAT(9E5.2)
1.0
0.98
1.0
0.90
0.97
1.0
0.70
0.82
0.93
1.0
0.54
0.68
0.83
0.96
1.0
0.64
0.75
0.85
0.92
0.95
1.0

Data stored in the ENDF format. Data may be stored in the ENDF format in a similarmanner, but with a record giving the ENDF MAT number, files, and section. The data isgiven in a file 3 entry, followed by the covariance file.
Example:C35001002 Covariance file for subentry 35001002
C35001002 The file is in ENDF File 33 format, also cross section as File 3
F35001002 6210 3,33
Cross section and covariances in ENDF-6 format
0.000000+0 0.000000+000006210 0 06.215100+4 1.496234+200006210 3102
8.256831+6 8.256831+6001316210 3102
31
26210 3102
0.110000+4 0.244474+2 0.135000+4 0.236065+2 0.162500+4 0.218757+26210 3102
0.187500+4 0.196988+2 0.225000+4 0.153861+2 0.275000+4 0.153043+26210 3102
0.350000+4 0.127367+2 0.450000+4 0.100073+2 0.625000+4 0.865960+16210 3102
0.875000+4 0.656557+1 0.112500+5 0.501474+1 0.137500+5 0.457034+16210 3102
0.175000+5 0.387133+1 0.225000+5 0.394818+1 0.275000+5 0.314252+16210 3102
0.350000+5 0.258191+1 0.450000+5 0.232481+1 0.550000+5 0.184880+16210 3102
0.700000+5 0.157094+1 0.900000+5 0.117749+1 0.110000+6 0.997426+06210 3102
0.135000+6 0.992993+0 0.162500+6 0.757935+0 0.187500+6 0.734009+06210 3102
0.225000+6 0.678500+0 0.275000+6 0.492988+0 0.350000+6 0.418481+06210 3102
0.450000+6 0.372564+0 0.550000+6 0.284066+0 0.700000+6 0.247658+06210 3102
0.900000+6 0.194466+0 0.000000+0 0.000000+0 0.000000+0 0.000000+06210 3102
0.000000+0 0.000000+000006210 0 06.215100+4 1.496234+20000621033102
0.000000+0 0.000000+00100621033102
0.000000+0 0.000000+0
1
5528
32621033102
0.100000+4 0.120000+4 0.150000+4 0.175000+4 0.200000+4 0.250000+4621033102
0.300000+4 0.400000+4 0.500000+4 0.750000+4 0.100000+5 0.125000+5621033102
0.150000+5 0.200000+5 0.250000+5 0.300000+5 0.400000+5 0.500000+5621033102
0.600000+5 0.800000+5 0.100000+6 0.120000+6 0.150000+6 0.175000+6621033102
0.200000+6 0.250000+6 0.300000+6 0.400000+6 0.500000+6 0.600000+6621033102
0.800000+6 0.100000+7 0.000000+0 0.000000+0 0.000000+0 0.000000+0621033102……………..
………………
0.300769-2 0.190133-2 0.194659-2 0.199179-2 0.196701-2 0.199724-2621033102
0.208640-2 0.362495-2 0.197938-2 0.202161-2 0.201359-2 0.205954-2621033102
0.216937-2 0.302796-2 0.208438-2 0.207471-2 0.212723-2 0.225324-2621033102
0.345695-2 0.212488-2 0.218017-2 0.231748-2 0.376135-2 0.218460-2621033102
0.232702-2 0.326855-2 0.242255-2 0.444583-2
0.000000+0 0.000000+000006210 0 0
E 35001002

0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24

103
104
105
106
107
108

See EXFOR Manual Appendix B for formats.

C.6

October 2004

LEXFOR

Cross sections(For fission cross sections, see Fission).
(For cross sections leading to isomeric states, see Isomeric States).
(See also Differential Data and LEXFOR entries for specific processes).
Definition: Cross sections are microscopic reaction probabilities, and are given as a functionof incident projectile energy.
Cross Section (integrated, as opposed to differential with respect to angle and/or energy ofsecondary particles).
REACTION coding: Process code SIG in SF6.
Units: code from Dictionary 25 with the dimension B (e.g., MB).
Example:(29-CU-63(P,N)30-ZN-63,,SIG)

Cross section integral between specified incident energy limits
Definition:

E2∫ σ dE

E1

REACTION Coding: INT in SF6 (parameter).
Units: code from Dictionary 25 with the dimension E*B (e.g., B*EV).
Example:(92-U-235(N,F),,INT)4

The energy limits are specified under the data-heading keywords EN-MIN and EN-MAX.
Such data may be coded only in the following cases:
1. When the data are normalized by means of an integral cross section over a specified
energy range, the integral may be entered under the keyword MONITOR.
2. When the differential data are not available.
3. When the energy ranges given are commonly used for inter-comparison of the data.
Generally, only data integrated by the experimentalist are compiled. Data that were notintegrated by the experimentalist should be entered with a comment clearing stating by whomthey were integrated.
Compilation of such data is optional.

4This code is not to be used for integral measurements.

November 2005

C.7

LEXFOR

Cross sections (continued)
Total Charge-Changing Cross Section
Definition: The cross section for the emission of all products whose charge differs from theincident projectile charge. That is, if Z0 is the incident projectile charge and Z1 is the chargeof a given product nucleus, then TCC is the cross section for the production of all nuclei suchthat Z1 =0 .
Sum rule:TCC=

tot í Z0=Z1

Example: REACTION(26-FE-56(6-C-12,TCC),,SIG)

Units: code from Dictionary 25 with the dimension B (e.g., MB).
Note: the partial charge-changing cross sectionZKLFKLV JLYHQ IRUSDUWLFOHVIRU D JLYHQ =(e.g. = í LVFRGHGDVDSURGXFWLRQFURVVVHFWLRQExample: REACTION(26-FE-56(6-C-12,X)ELEM,,SIG)

The charge is given in the COMMON or DATA section under the data heading
ELEMENT. Units are NO-DIM.
Spin-dependent total cross sections (See also Polarization).
Definitions: σSS = (σ↑↓ - σ↑↑)/2 Spin-spin cross section∆σ = σ↑↓ - σ↑↑Spin-dependent difference cross sectionwhereσ↑↑ = cross section for incident-projectile and target spins parallelσ↑↓ = cross section for incident-projectile and target spins anti-parallel

REACTION Coding:Spin-spin cross section: modifier SS in SF8.
Example:(…(N,TOT),,SIG,,SS)

Spin-dependent difference cross section: modifier DSP in SF8.
Example:(…(N,TOT),LON,SIG,,DSP) Total spin difference cross section for purelongitudinal spin states
Units: a code from Dictionary 25 with the dimension B (e.g., MB).

C.8

October 2004

LEXFOR

Data TypeThe last subfield of the REACTION code string (SF9) contains a code to indicate whether thedata given are experimental, theoretical, evaluated, etc.
Experimental Data
The default data type is experimental. That is, if the data are experimental this field may beomitted.
Derived Data
Data that are not derived from the experimental data by the most direct method, but are,instead, calculated from other data obtained in the analysis of the experimental data, should
be entered using the code DERIV in SF9 (Data type) of the REACTION code string.
Only values derived by the experimentalist from his own data should be entered in this way.
If the data from which the value given is derived are entered in an EXFOR subentry, a crossreference to that subentry should be entered under the STATUS code DEP, see Status.
At present, the following types of derived data are entered in EXFOR system:• Resonance integrals derived from resonance parameters or energy-dependent crosssections.
• Thermal cross sections calculated from resonance parameters.
• Angular distributions calculated from fitting coefficients.
• Cross-section values at one energy (e.g., at 0.0253 eV) or spectrum averages derived froma smooth fit to measured points.
• Data calculated from the sum or difference of two or more measurements.
• Thick target yields derived from cross sections or cross sections calculated from thicktarget yields.
• Data calculated using measurements for an inverse reaction.
• ν calculated from fission yields.
Evaluated and Theoretical Data
Evaluated and theoretical data are, generally, not included in EXFOR with the current
exception for photonuclear data.
If such data are compiled in EXFOR, the data type EVAL or THEOR must be given.

November 2005

D.1

LEXFOR

Decay Data
(See also Half Lives).
Radioactive decay data are not compiled in the EXFOR format except as additional
information relevant to the measurement of a reaction quantity.
Information-Identifier Keyword DECAY-DATA.
The following decay data pertinent to the table given in the DATA section, are entered in the
BIB section under DECAY-DATA in coded form:• decaying nucleus (even if decays from the daughter nucleus are measured)• half-life (value and unit)• type of radiation• energy of radiation in keV,
• abundance of the radiation measured.
These data may be given for more than one decay mode.
DECAY−DATA for coding rules.

See EXFOR Chapter 7:

Decay data are entered:• in order to define an isomeric state, or• when used as basic parameters for deducing the data given in the DATA section.
Free text explanation is often desirable, for example, a statement on whether the decay data
were obtained from the experiment or quoted from another source. If the data given are takenfrom a known source, the reference for may be coded under the Information-Identifier
Keyword REL-REF (see Reference).
Where unresolved doublets (or multiples) of γ-rays were used in the publication, the energiesof all involved γ-rays, or at least the lowest and the highest energy, should be given, separated
by a slash. Thus, two energy values given can mean a doublet or the borders of the energy
range containing all (unresolved) γ-rays that were used for the analysis.
Example: DECAY-DATA (Z-S-A-X,3.1HR,DG,876./892.,0.80)
where 0.80 is the total abundance of the two γ-rays at 876 and 892 keV, or of all γ-rays
lying between the limits 876 and 892 keV. For γ-transitions, the photon abundanceshould be included, if given by the authors.
Only the values used by the author to obtain the data should be entered in coded form.
Values assumed by the compiler may be entered in free text only.
Information-Identifier Keyword DECAY-MON
Decay data assumed or measured by the author for a reaction used in the experiment as astandard (or monitor) are entered under the information-identifier keyword DECAY-MON.
See EXFOR Manual Chapter 7: DECAY-MON, for coding rules. (See Standards forexample).

D.2

November 2005

LEXFOR

Decay Data (continued)
Decay Data for Variable Product Nuclei
In the case of variable product nuclei, where the reaction product is defined in the COMMON
or DATA section using the data-heading keywords ELEMENT and MASS, the decay data
information is coded as strings of information under the keyword DECAY-DATA and may belinked to the reaction product using the data-heading keyword DECAY-FLAG. In particular,when decay data are given for parent or daughter nuclides of the specified product, the data
should be linked in this way. (See EXFOR Chapter 6: Variable Nucleus). (See also Flags).
More than one string of decay data information for a specific product may be entered byrepeating the decay flag for each string.
Example:DECAY-DATA

ENDBIBNOCOMMONDATAELEMENTNO-DIM
54.
54.
55.
…
ENDDATA((1.)54-XE-125-G,16,8HR,…)((2.)54-XE-127-M,69.SEC,…)((2.)54-XE-127-G,36.4D,…)((3.)55-CS-127,6.25HR,…)MASSNO-DIM
125.
127.
127.
…

ISOMER
NO-DIM
0.
0.
…

DECAY-FLAG
NO-DIM
1.
2.
3.
…

DATA
PC/FIS…
…
…
…

Decay Data Errors
Numerical values for the errors in the decay data given may be entered in the COMMON or
DATA sections using the data headings:
ERR-HLerror in half-life given in DECAY-DATA

ERR-EDD error in energy given in DECAY-DATA
ERR-IDD error in abundance given in DECAY-DATA

November 2005

D.3

LEXFOR

Delayed Fission Neutrons
TheoryIn certain cases, a fission-product nucleus may decay by β decay to excited levels in thedaughter nucleus which lie above the neutron binding energy. In this case, a delayed neutron
may be emitted whose measured half-life is equal to that of the preceding β emitter (delayed
neutron precursor). These half-lives are of the order of 0.1 to 60 sec, which is large
compared to the period of prompt neutron emission (<<4×10-14 sec, see Fission Yield)
Schematic representation of delayed-neutron emission.

Z,A

β−

n

Bn
Z+1,A

Z+1,A-1

where Bn = neutron binding energy of the nucleus Z+1,A

Delayed-neutron groups
Delayed-neutron emission is sometimes represented by delayed-neutron groups (usually 6),
distinguished by their half-lives. Each group is associated with, perhaps, several different
precursor nuclides with similar half-life values (e.g., 55 sec, 22 sec, 6 sec, 2 sec, 0.5 sec and0.2 sec).
For further detail see Amiel [1], Keepin [2], and Hyde [3].

D.4

November 2005

LEXFOR

Delayed Fission Neutrons (continued)
Definitions and codes of quantities for data to be compiled in the EXFOR System
1. Total average delayed fission neutron yield (ν )REACTION Coding: NU in SF6 (parameter) and DL in SF5 (Branch)a. Absolute delayed neutron yield
Units: a code from Dictionary 25 with dimension FY (e.g., PRT/FIS)1
Example: (…(N,F),DL,NU)b.

2.

Delayed neutron fraction (ν d /ν ): coded as a ratio with the units NO-DIM:
Example: ((…(N,F),DL,NU)/(…(N,F),,NU))
Partial delayed fission neutron yields

a. Delayed neutron Groups: coded using the average half-life of the group (HL), the decay
constant (DCNST), or the group number (GRP-NUM)2 as an independent variable.
• Relative abundance (or relative group yield): coded as the ratio. (The values for the six
groups sum up to 1).
REACTION Coding: ((…(N,F),DL/GRP,NU)/(…(N,F),DL,NU))
Units: NO-DIM• Absolute group yield:
REACTION Coding: (…(N,F),DL/GRP,NU)
Units: a code from Dictionary 25 with dimension FY (e.g., PRT/FIS).
b. Yield of delayed fission neutrons associated with an individual precursor: Coded withthe precursor nucleus as an independent variable given under the data headings ELEMENT
and MASS, usually with units PC/FIS, as above. (See EXFOR Manual Chapter 6).
3. Delayed-Neutron Energy Spectrum for a Given Neutron Group
REACTION Coding: (…(N,F),DL/GRP,DE,N)
Data are coded using the average half-life of the neutron group and the delayed neutronenergy or energy range as independent variables.
The data may be given:a. in neutrons/fission - the data unit PART/FIS is used.
b. as a relative measurement - the quantity modifier REL and data units ARB-UNITS areused.
For the preceding quantities, the nucleus to be entered is the target nucleus before theabsorption of the incident particle.
c. delayed neutron fraction: group ratio to total delayed neutron yield – coded as a ratiowith units NO-DIM.
1
2

Older entries may have used the units NO-DIM.
The group number should only be given if the half-life or decay constant is not given.

November 2005

D.5

LEXFOR

Delayed Fission Neutrons (continued)
4. Delayed-neutron Emission Probability (Pn value)
Definition: Neutron yield per β decay for a given nucleus. This is a decay quantity of thefission product nucleus and is independent of the fissioning target nucleus. It is related to
the fission yield byabsolute delayed neutron yieldPn =cumulative fission yield
REACTION Coding:a.

((Z-S-A(0,B-)Z’-S’-A’,,PN) for a single fragment
where:
Z-S-A is the fission product nucleus (precursor nucleus before β decay);
Z'-S'’-A' is the delayed-neutron emitting fission fragment.

b.

(ELEM/MASS(0,B-),,PN) for a series of fragments
The fission product nucleus is entered as a variable in the data table (see EXFOR
Chapter 6: Variable Nucleus).

Units: a code from Dictionary 25 with dimension PN (e.g., PC/DECAY)
For delayed neutron emission probabilities see for example, Amarel [4], Tomlinson [5],and Asghar [6].
For spontaneous fission enter the fissioning nucleus and code as a nuclear quantity. See
Fission.
Data not presently compiled in EXFOR• The energy spectrum of all delayed neutrons together, which is time dependent, due to thecontributions from the different half-life groups.
• The delayed-neutron equilibrium spectrum as found in a steady-state reactor.
There are other delayed-neutron quantities that are not properties of the fissioning nucleus but
decay properties of the fission-product nucleus that is the "precursor" of the delayed neutron.
Quantities in this category that are presently not coded in EXFOR:• the energy spectrum of the neutrons emitted by a specific precursor.
References[1.] S. Amiel, IAEA Panel on Fission-product Nuclear Data, Bologna, 1973, IAEA report
IAEA-169, Vol. II (1973) p. 33[2.] G.R. Keepin, Physics of Nuclear Kinetics (Addison-Wesley, 1965) Chapter 4[3.] E.K. Hyde, The Nuclear Properties of Heavy Elements, Vol. III (Prentice Hall, 1964)
p. 261 ff.
[4.] I. Amarel, et.al., J.Inorg.Nuc.Chem., 31, 577 (1969)[5.] L. Tomlinson, et.al., J.Inorg.Nuc.Chem., 33, 3609 (1971)[6.] M. Asghar, et.al., Nucl.Phys.A, 247, 359 (1975)

D.6

November 2005

LEXFOR

Dependent Data
Data that are deduced by a trivial operation from other data sets entered into the EXFOR
System should be labeled with the code DEP under the keyword STATUS. Free text under
STATUS and/or ANALYSIS should give information as to how the data were deduced.
Cross-reference to the EXFOR entries from which the data were deduced must be coded as
an eight-digit integer following the code.
Example: STATUS(DEP,10048007)

Examples of data that would be labeled as dependent data:a. Alpha obtained from the ratio of two independent data sets for fission and capture.
b. Radiation width obtained from a subtraction of two independent data sets of total widthand elastic width.
c. Legendre- or Cosine-coefficients, when the originally measured differential cross sections
are also entered.
d. If the same data are given in two different representations, e.g., cross section and crosssection times square-foot of energy, one of them should have the status code DEP.
The status code DEP should not be used when some data sets are mutually interdependent, as
for example:• A simultaneous measurement of absorption and capture cross sections, and alpha, where
all three interdependent quantities were derived from a common set of raw data. None ofthese should be labeled with the status code DEP.
Compare: Status: Interdependent Data.
Note: Do not confuse the use of the status code DEP with the use of the data type DERIV(derived data), see Data Type.

November 2005

D.7

LEXFOR

Dependent Variable
The dependent variable is defined under the REACTION code string. The data is given in thedata table using the data heading DATA, or its derivatives, see below.
Each line in a data table must contain a value for the dependent variable, i.e., at least one fieldheaded by the data heading DATA, or its derivatives, on each line must contain a value (seeexamples, below).
The following derivatives of the heading DATA are used:
DATA-MIN Lower limit
DATA-MAX Upper limit
DATA-APRX Approximate value
DATA-CM
Quantity given in center-of-mass system (see Center-of-Mass System).
Examples:1) The following is a legal data table.
DATA
EN
MEV
1.0
2.0
3.0
ENDDATA

DATA
B
2.22

DATA-MIN
B
4.

3.33

2) The following is an illegal data table.
DATA
EN
MEV
1.0
2.0
3.0
ENDDATA

DATA
B
2.22

MONIT
B
3.

3.33

For the coding of uncertainties, see Errors.

D.8

November 2005

LEXFOR

Differential Data
(See also Fitting Coefficients, Angle, Polarization).
Definitions
Reaction plane: The plane defined by the incident beam direction and the outgoing particle
direction. For the following discussions plane A is defined by the incident beam direction
and the outgoing particle a direction
Differential data refers, in general, to one of the folloowing:• the particle given in the REACTION string SF3,
• for production or fission, the product given in SF4 or in the data table• the particle defined in the REACTION string SF7.
A particle must be specified in SF7 (particle considered) if:• there is more than one particle given in SF3,
• the data refers to a different particle or nuclide than those specified above,• or the data refers to more than one outgoing particle.
The use of the term distributions shall also refer to data measured for an individual point.
Reference System
An indication that the differential cross section, the angle, or the energy is given in center-ofmass system is given in the data headings; see Center-of-Mass System.
Angular Distributions3 (dσ/dΩ)
1. Angular distribution: probability for a particle to be emitted into an area of solid angle dΩ
lying at a mean angle of θ to the incident beam direction in the reaction plane; given as σ(θ)= dσ/dΩ. The data are given in units of cross section per unit solid angle (e.g., mb/sr).

beam

θ

REACTION coding: DA in SF6.
Unit type: DA (e.g., B/SR)
2. Relative angular distributionsa.) The shape of the angular distribution W(θ); the data are dimensionless, and are mostoften normalized to W(90°) = 1.
REACTION coding: DA in SF6; modifier REL in SF8.
Units: ARB-UNITS.
b.

Ratio to 90°
REACTION coding: DA in SF6; modifier RSD in SF8.
Units: NO-DIM

3

Historically the term differential cross section has been used to refer to dσ/dΩ and the term excitation function
to dσ/dΩ at one angle as a function of incident projectile range.

November 2005

D.9

LEXFOR

Differential Data (continued)c. Ratio to 0°
REACTION coding: DA in SF6; modifier RS0 in SF8.
Units: NO-DIM
d. Ratio to average value from 0° - 180°:

dσ
σ
(θ )
dΩ
4π

REACTION coding: DA in SF6; modifier RS in SF8.
Units: NO-DIM
e. Ratio to the value at another angle:dσ
dσ(θ 1 )(θ 2 )dΩdΩCode as a ratio using the separator //, see Ratios.
The angle for the numerator is coded under ANG-NM; the angle for the denominator iscoded under ANG-DN.
f. Ratios to the integrated cross section:
Code as a ratio with the separator /, see Ratios.
g. Ratio to Rutherford or Mott scattering4
REACTION coding: DA in SF6; modifier RTH (Rutherford) or MOT (Mott) in SF8.
Units: NO-DIM
3. Angular distribution for a correlated pair: Probability that a particle a and a particle b will
be emitted at a mean angle θm to the incident beam, dσ/dΩ for θm:

θm

REACTION coding: DA in SF6; particles in SF7 as a+b (e.g., P+A).
Unit type: DA (e.g., B/SR)
The angle is given under the heading ANG-MN
4. Angular correlation: probability that, if a particle a in emitted at a mean angle of θa to theincident beam direction in the reaction plane, particle b will be emitted at a mean angle of θbto the incident beam direction in the same plane (coplanar); given as d2σ/dΩadΩb. The data
are given in units of cross section per unit solid angle squared (e.g., mb/sr2).
θa
θb

4

See Scattering for definitions of Rutherford and Mott scattering.

D.10

November 2005

LEXFOR

Differential Data (continued)
REACTION coding: DA/DA in SF6; particles in SF7 as a/b (e.g., P/D).
Unit type: DA2 (e.g., MB/SR2)
The angles θa and θb are coded under the headings ANG1 and ANG2, in the same order as theparticles appear in SF7. If the particles are measured on opposite sides of the beam direction,
the angles will be given as, for example, 30. and –30.
Alternately, the angle of particle b, θb, may be given with the angle between the two emitted
particles θrel.
θ re lθa

REACTION coding: DA/DA in SF6; particles in SF7 (e.g., P/P+A).
Unit type: DA2 (e.g., MB/SR2)
The angles are given as ANG1 and ANG-RL.
The angular correlation is often given as an angular correlation function W(θa,θb); the data
are dimensionless.
REACTION coding: DA/DA in SF6; particles in SF7, REL in SF8.
Units: ARB-UNITS.
5. Non-coplanar angular correlations: The more general situation is for particle a andparticle b not in the same reaction plane. Then θa is the angle of particle a relative to thebeam direction in plane A, θb is the angle of particle b relative to the beam direction in planeB, and a third angle φ is defined as the angle between the A and B reaction planes (azimuthal
angle).
φ

REACTION coding: DA/DA in SF6; particles in SF7 as a/b (e.g., N/P) ; NCP in SF8.
Unit type: DA2 (e.g., MB/SR2).
The angles θa and θb are coded under the headings ANG1 and ANG2, in the same order as theparticles appear in SF7. The azimuthal angle is coded under the heading ANG-AZ.
The angular correlation function is then given as W(θa,θb,φ).
REACTION coding: DA/DA in SF6; particles in SF7; NCP/REL in SF8.
Units: ARB-UNITS

November 2005

D.11

LEXFOR

Differential Data (continued)
Secondary Energy Distributions (dσ/dE
1. Energy distributionSUREDELOLW\IRUDSDUWLFOHWREHHPLWWHGZLWKDJLYHQHQHUJ\( RULQD
given energy range Emin to Emax; given as σ (  Gσ/dE 7KHGDWDDUHJLYHQLQXQLWVRIFURVV
section per unit of secondary energy (e.g., mb/MeV).
REACTION coding: DE in SF6.
Unit type: DE (e.g., B/MEV)
2. Energy distribution for a correlated pair: Probability that a particle a and a particle b will
be emitted at a relative energy Erel, usually given as the center-of-mass energy of the relative
motion of the correlated pair:
REACTION coding: DE in SF6; particles in SF7 as a+b (e.g., P+A).
Unit type: DE (e.g., B/MEV)The energy is given under the data heading E-RL-CM
3. Linear momentum distribution: probability for a particle to be emitted with a given
PRPHQWXPS JLYHQDVσ S  Gσ/dp. The data are given in units of cross section per unit ofsecondary linear momentum (e.g., mb/MeV/c).
REACTION coding: DP in SF6.
Unit type: DP (e.g., MB/MEV/C)
Example:(……(N,X)……,LP,DP) longitudinal momentum distribution of emitted particles.
The linear momentum is given under the data heading MOM-SEC.
4. Linear momentum distribution for a correlated pair: Probability that a particle a and aparticle b will be emitted at a mean linear momentum pm or a relative linear momentum prel.
REACTION coding: DP in SF6; particles in SF7 as a+b (e.g., P+A).
Unit type: DP (e.g., MB/MEV/C)
The linear momentum is given under the heading MOM-SEC-MN or MOM-SEC-RL.
Angle/Energy Distributions
1. Angle/energy distribution d2σ/dΩ/dE  SUREDELOLW\ IRU D SDUWLFOH WR EH HPLWWHG DW D JLYHQ
HQHUJ\( DQGLQWRDQDUHDRIVROLGDQJOHΩ lying at a mean angle of θ to the incident beam
direction in the reaction plane; given as σ(E θ) = d2σ/dΩ/dE 7KHGDWDDUHJLYHQLQXQLWVRI
cross section per unit solid angle per unit of energy (e.g., mb/sr/MeV).
REACTION coding: DA/DE in SF6.
Unit type: DAE (e.g., B/SR/MEV)The energy is given under the data heading E or E-MIN and E-MAX.

D.12

November 2005

LEXFOR

Differential Data (continued)
2. Angle/energy correlations:a.) d3σ/dΩdΩdE SUREDELOLW\WKDWLI
• either a particle a in emitted at a mean angle of θa to the incident beam direction in the
UHDFWLRQ SODQH DQG DQ HQHUJ\ (  SDUWLFOH b will be emitted at a mean angle of θb to theincident beam direction in the same plane (coplanar); given as d3σ/dΩadΩbdEa
REACTION coding: DA/DA/DE in SF6, . particles in SF7 as a/b/a (e.g., P/A/P)
The angles θa and θb are coded under the headings ANG1 and ANG2 in the same order as
the particles appear in SF7; the energy is coded under the heading E1 or E2 to correlate
the energy with the angle of the same particle.
• or a particles a and b will be emitted at mean angles of θa and θb to the incident beam
direction in the reaction plane, with a relative energy E rel, usually given as the center-ofmass energy of the relative motion of the correlated pair; given as d2σ/dΩadΩbdErel
REACTION coding:

DA/DA/DE in SF6, . particles in SF7 as a/b/a+b (e.g., P/A/P)

The angles θa and θb are coded under the headings ANG1 and ANG2 in the same order as
the particles appear in SF7; the energy is coded under the heading E-RL.
The data are given in units of cross section per unit solid angle squared per unit energy(e.g., mb/sr2/MeV).
Unit type: D3A (e.g., MB/SR2/MEV)
Examples:
BIB
REACTION
…
DATA
ANG1
ADEG

(…(P,N+P)…,,DA/DA/DE,P/N/P)

…

ANG2
ADEG

E1
MEV

…

…

DATA
MB/SR2/M
EV

For the case where the mean energy is given for a correlated pair:
BIB
REACTION
…
DATA
ANG1
ADEG
…

November 2005(……,,DA/DA/DE,A/T/A+T)

ANG2
ADEG
…

E
MEV
…

DATA
MB/SR2/MEV

D.13

LEXFOR

Differential Data (continued)b.) d3σ/dΩ/dE G( SUREDELOLW\WKDWLI D SDUWLFOH a in emitted at a mean angle of θa to theincident beam direction in the reaction plane and an energy Ea, particle b will be emitted
at an energy Eb; given as d3σ/dΩa/dEa/dEb. The data are given in units of cross section
per unit solid angle per unit energy squared (e.g., mb/sr/MeV2).
REACTION coding: DA/DE/DE in SF6, . particles in SF7 as a/b/a (e.g., P/A/P)
Unit type: D3 (e.g., MB/SR/MEV2)The energies are coded under the data heading E1 and E2 in the same order as theparticles appear in SF7; the angle θa is coded under ANG1 or ANG2 to correlate with theenergy of the same particle.
c.) d4σ/dΩ/dΩ/dE /dE : probability that, if a particle a in emitted at a mean angle of θa to theincident beam direction in the reaction plane and an energy Ea, particle b will be emitted
at a mean angle of θb to the incident beam direction in the reaction plane and an energy
Eb; given as d4σ/dΩa/dΩb/dEa/dEb. The data are given in units of cross section per unit
solid angle per unit energy squared (e.g., mb/sr2/MeV2).
REACTION coding: DA2/DE2 in SF6, . particles in SF7 as a/b (e.g., P/A)
Unit type: D4A (e.g., MB/SR2MEV2)
The angles θa and θb are coded under the headings ANG1 and ANG2 in the same order as
the particles appear in SF7; the energies are, similarly, coded under the headings E1 andE2.
d.) Angle/linear momentum distribution d2σ/dΩ/dp: probability for a particle to be emitted
ZLWK D JLYHQ PRPHQWXP S  DQG angle θ; given as σ(θS   G2σ/dΩ/dp. The data are
given in units of cross section per unit of solid angle per unit of secondary linear
momentum (e.g., mb/MeV/c).
REACTION coding: DA/DP in SF6.
Unit type: DAP (e.g., MUB/SRMEVC)
The linear momentum is given under the data heading MOM-SEC.
Treiman-Yang Angular Distribution
Definition: The angular distribution measured as a function of the angle between two
reaction planes for three-particle final states in the anti-laboratory system (i.e., X is at rest).
That is, for the reaction between particles X and Y producing particles a, b, c (see diagram
below), the angle between the planes (X,a,b) and (Y,c). Data are given in the center-of-masssystem.
a

X0
b

c
Y

D.14

November 2005

LEXFOR

Differential Data (continued)
For photonuclear reactions in the center-of-mass system, it is the angle between the (X,a) and(Y,b) or (Y,c) planes, where X is the incident gamma, Y is the target nucleus.
(X,a)
a

X

c
(Y,c)

Y

See Shapiro5 for more information.
The reaction planes are defined as:• Plane 1: defined by target (SF1) and residual nucleus (SF4)• Plane 2: defined by incident projectile (SF2) and particle designator (SF7)
REACTION coding: parameter code DA/TYA in SF6, outgoing particle in SF7.
Example:REACTION(2-HE-4(G,N+P)1-H-2,,DA/TYA,P) distribution

over Treiman-Yang
angle between (4He,2H) and (γ,p)
planesThe data headings ANG-AZ-CM and DATA-CM should be used in the data table.

5

I. S. Shapiro et al., Nucl.Phys. 61, 353 (1965)

November 2005

D.15

LEXFOR

Dosimetry Neutron Reaction Data
(See also Standards).
A list of the "most-needed" neutron reaction data identification follows.
Activation Reactions (for use with neutron threshold detectors)
3-LI-6(N,X)2-HE-4
5-B-10(N,X)2-HE-4
7-N-14(N,P)6-C-14
9-F-19(N,2N)9-F-18
11-NA-23(N,G)11-NA-24
11-NA-23(N,2N)11-NA-22
12-MG-24(N,P)11-NA-24
13-AL-27(N,A)11-NA-24
13-AL-27(N,P)12-MG-27
15-P-31(N,P)14-SI-31
16-S-32(N,P)15-P-32
21-SC-45(N,G)21-SC-46
21-SC-45(N,2N)21-SC-44
21-SC-45(N,2N)21-SC-44-M
22-TI-46(N,P)21-SC-46
22-TI-47(N,N+P)21-SC-46
22-TI-47(N,D)21-SC-46
22-TI-47(N,P)21-SC-47
22-TI-47(N,P)21-SC-47
22-TI-48(N,P)21-SC-48
22-TI-48(N,N+P)21-SC-47
25-MN-55(N,2N)25-MN-54
25-MN-55(N,G)25-MN-56
26-FE-54(N,P)25-MN-54
26-FE-54(N,A)24-CR-51
26-FE-56(N,P)25-MN-56
26-FE-58(N,G)26-FE-59
27-CO-59(N,P)26-FE-59
27-CO-59(N,A)25-MN-56
27-CO-59(N,2N)27-CO-58
27-CO-59(N,G)27-CO-60

28-NI-58(N,P)27-CO-58
28-NI-58(N,2N)28-NI-57 → 27-CO-57
28-NI-60(N,P)27-CO-60
29-CU-63(N,A)27-CO-60
29-CU-63(N,2N)29-CU-62
29-CU-63(N,G)29-CU-64
29-CU-65(N,2N)29-CU-64
30-ZN-64(N,P)29-CU-64
30-ZN-64(N,2N)30-ZN-63
40-ZR-90(N,P)39-Y-90
40-ZR-90(N,2N)40-ZR-89
41-NB-93(N,INL)41-NB-93-M
41-NB-93(N,2N)41-NB-92-M
42-MO-98(N,G)42-MO-99 → 43-TC-99-M
45-RH-103(N,INL)45-RH-103-M
47-AG-109(N,G)47-AG-110-M
49-IN-115(N,INL)49-IN-115-M
49-IN-115(N,G)49-IN-116-M
53-I-127(N,2N)53-I-126
73-TA-181(N,G)73-TA-182
74-W-186(N,G)74-W-187
79-AU-197(N,G)79-AU-198
79-AU-197(N,2N)79-AU-196
79-AU-197(N,3N)79-AU-195
79-AU-197(N,4N)79-AU-194
80-HG-199(N,INL)80-HG-199-M
90-TH-232(N,2N)90-TH-231
90-TH-232(N,G)90-TH-233 → 91-PA-233
92-U-238(N,G)92-U-239 → 93-NP-237

Fission Reactions
90-TH-232(N,F)
92-U-235(N,F)
92-U-238(N,F)

D.16

93-NP-237(N,F)
94-PU-239(N,F)
95-AM-241(N,F)

November 2005

LEXFOR

Elements
Naturally occurring elements are, in general, entered with A=0 (e.g., 26-FE-0).
However, for monoisotopic elements, the atomic weight of the naturally occurring isotope isused. A list of monoisotopic elements follows.
4-BE-99-F-1911-NA-23
13-AL-27
15-P-3121-SC-45
25-MN-55

27-CO-59
33-AS-75
39-Y-89
41-NB-93
45-RH-103
53-I-127
55-CS-133

59-PR-141
65-TB-159
67-HO-165
69-TM-169
79-AU-197
83-BI-209
90-TH-232

Nearly monoisotopic elements may be entered with the A (mass number) of their mainisotope only in cases where there is no noticeable influence from trace isotopes on the data
presented, e.g., most total and elastic scattering cross sections. Special care should be takenwith the capture cross section. Partial cross section leading to levels in one of the trace
isotopes should always be coded under that isotope.
Following is a list of nearly monoisotopic elements:
1-H-1
2-HE-4
6-C-12
7-N-148-O-1623-V-51
57-LA-139
73-TA-181

Note: Elements that do not occur naturally must be entered with the isotope number:
43-TC
61-PM
84 ≤ Z ≤ 89

91-PA
93 =Super-heavy elements that do not have an element symbol are coded using an * for theelement symbol (e.g., 112- ). See Dictionary 8.
Note: The hydrogen isotopes are always coded using the element symbol H, (e.g., 1-H-2,
1-H-3).
See also Target Nucleus.

November 2005

E.1

LEXFOR

Errors(See also Covariance, Resolution).
Definition: The uncertainty on the mean value of a variable1.
Information-Identifier keyword ERR-ANALYS
Free text explanation of the error sources and of the numerical uncertainties values is given
under the keyword ERR-ANALYS. In order to link the explanations to the numerical data,
the relevant data headings are given in parentheses, starting in column 12, and are followed
by free text; when only one data error is given, the data heading need not be given (seeEXFOR Manual Chapter 7: ERR-ANALYS). Free text should contain a statement of theerror type included in the quoted uncertainties, and also those error types that are notincluded.
The numerical uncertainty values quoted in the COMMON or DATA section are relevant
only in conjunction with an appropriate entry under ERR-ANALYS, explaining the type of
uncertainty and percentage of contributing uncertainties. Therefore, the compiler should be
careful to define the information given. The following aspects are useful for a precise
definition of the uncertainty:
1. error-type, such as:• statistical or random uncertainty (uncorrelated)• systematic uncertainties (may be correlated)sample related: mass, geometric effects, multiple scattering, self-absorption.
detector related: efficiency, calibration
normalization: monitor cross section, flux determination
2. total error or partial error, for example, the statistical uncertainty, which is most often apartial along with other uncertainties, may be the total uncertainty if other sources of
uncertainty are negligible.
3. shape of error function, such as:• Gaussian, symmetric• triangular, symmetric• unsymmetric, for example 8.5+0.5/-0.2
4. error measure, such as:• standard deviation = half-width at half-maximum of Gaussian error distributionfunction= 2/3 probability that the true value is within error bars
• confidence limits: when errors are given as confidence limits various definitions exist,
for example, 95% probability, which corresponds to approximately
two standard deviations.
• errors supposed not to exceed: approx. 100% probability value is within error bars.
5. error correlations: within systematic uncertainties and with other quantities measured in
the same experiment; see also Status: Interdependent Data.
1

The terms error and resolution are often misused in the literature. Distinguish between them where possible.
See Resolution.

E.2

November 2005

LEXFOR

Errors (continued)
Energy Uncertainties
Numerical values for the uncertainty in a monochromatic incident-neutron energy or of themean energy in an incident-neutron spectrum may be entered in the COMMON or DATA
section using data headings from Dictionary 24 with the family code B, e.g., EN-ERR.
Further information can be given in free text under the information-identifier keyword
ERR $1$/<6.
Data Uncertainties
Information on the uncertainties associated with the data compiled is entered in one of two
ways depending on whether a complete analysis of the uncertainties has been done.
Detailed analysis of the uncertainties has not been done or the compiler does not haveenough information to know if a complete analysis has been done.
The uncertainties should be entered in one of the following ways:
1. in the COMMON or DATA section under the data heading DATA-ERR with an
explanation in free text under ERR-ANALYS. If two or more errors of different types are
given referring to the same data, data headings of the type DATA-ERR1 and DATAERR2 are used.
Unsymmetrical errors are identified using the data headings+DATA (55 and í'$7$ (55. Statistical uncertainty may be entered as ERR-S; total
systematic or correlated uncertainty may be entered as ERR-SYS.
2. as free text information under ERR-ANALYS.
Detailed and complete analysis of the uncertainties has been done.
The detailed error formats are used:
1. The numerical values for the statistical and systematic uncertainties are entered in the
COMMON or DATA section under the data headings ERR-S and ERR-SYS, as above,
The total uncertainty is entered under ERR-T (total) with the partial systematic
uncertainties entered under ERR , ERR , etc. (see Dictionary 24). The definition of
the different systematic uncertainties is given under ERR-ANALYS in free text comments
preceded by a code containing the relevant data heading. Constant systematic
uncertainties may, alternately, be entered in free text under ERR-ANALYS.
2. Only uncertainties that are one standard deviation (or the equivalent for systematic
uncertainty) are entered in this format. If the author gives 2- or 3-sigma uncertainties, theyshould be converted to 1-sigma uncertainties before entering. Other types of uncertainty
information may be entered in free text.
3. The correlation factor for the systematic uncertainties is coded under ERR-ANALYS
following the data-heading code, if known.
See example, following.

November 2005

E.3

LEXFOR

Errors (continued)
Emphasis should be given to the compilation of detailed information on the uncertainties forexperimental data on neutron cross sections for standards (see Standards) and dosimetry
reactions (see Dosimetry Neutron Reaction Data). When the required error information forthese data is not given in the literature, every effort should be made to obtain it from theexperimentalists.
Error Correlations
Data that have been measured by the same technique have certain systematic error sources incommon and are, therefore, interdependent; their errors are correlated.
Examples:ν for 233U and 235U, both measured in the same manganese bath.
Absorption, ν DQG DOOREWDLQHGVLPXOWDQHRXVO\LQWKHVDPHH[SHULPHQW
Evaluators must carefully consider error correlations. Therefore, the compiler should attempt
to enter all required information on common error sources and cross-references between
interdependent data sets or subentries. This is particularly worthwhile in the case of private
communications; in other cases, evaluators might rather use published references.
The correlation factors are entered as a second field under the information-identifier keyword
ERR-ANALYS; see example, following page.
Digitizing Errors
Errors in the digitizing of a data set by a compiler are given under a separate set of heading:
ERR-DIG Error in digitizing data values
ANG-ERR-D

Error in digitizing the angle values.

E-ERR-DIG

Error in digitizing the secondary energy values.

EN-ERR-DIG

Error in digitizing the incident energy values.

Other Uncertainties: For uncertainty in mean secondary energy, see Secondary Particles.
For uncertainty in mean angle, see Angle. See index for information on other uncertainties.

E.4

November 2005

LEXFOR

Errors (continued)
Example of coding for detailed analysis of uncertainties:
BIB
REACTION
ERR-ANALYS

COVARIANCE

ENDBIB
COMMON
ERR-1
PER-CENT
1.5
ENDCOMMON
DATA
EN
ERR-3
MEV
PER-CENT
3.800
1.0
3.800
1.0
4.065
1.0
4.361
1.0
4.656
1.0
4.954
1.0
5.268
1.3
ENDDATA((29-CU-63(N,A)27-CO-60,,SIG)/(92-U-238(N,F),,SIG))
Uncertainty in neutron energy about 10 keV.
(ERR-T)(ERR-S)
Sources of Systematic Uncertainties(ERR-1,1.0) Gamma-ray detection efficiency.
(ERR-2,0.0) Irradiation geometry.
(ERR-3,1.0) Uranium deposit, mass, and isotopic content(ERR-4,1.0) Correction for the neutron absorption in Cu sample(ERR-5,0.5) Neutron source characteristics.
Only above diagonal elements of symmetric matrix are given in% on same energy grid as data.
100
17
19
29
23
14
13
100
37
39
45
28
28
100
42
48
29
26
1
100
50
31
30
100
35
30
100
22
100

ERR-5
PER-CENT
1.5

EN-RSL-HW
ERR-4MEV
PER-CENT
0.081
1.8
0.082
1.8
0.041
1.8
0.041
1.8
0.042
1.8
0.043
1.9
0.045
1.9

DATA

ERR-T

ERR-S

ERR-2

NO-DIM

PER-CENT

PER-CENT

PER-CENT

2.42

-04

13

12.

3.3

1.84

04

22

21.

2.6

5.142 -04

6.5

4.7

2.0

9.769 -04

5.7

3.8

2.0

1.475 -03

5.6

3.6

2.0

2.409 -03

5.0

2.4

2.0

3.912 -03

8.7

7.5

1.7

(Blank page)

November 2005

E.5

LEXFOR(Blank page)

E.6

November 2005

LEXFOR

Fission(See also Fission Yields, Fission-Neutron Spectra, Delayed Fission Neutrons).
Theory: The following definition applies in the low energy region and is based on currently
accepted models.
When a nucleus is excited with sufficient energy such that the electrostatic repulsion will begreater than the surface forces holding the nucleus together, it may undergo scission. At thescission stage the nucleus generally divides into two deformed and excited fission fragmentsof comparable mass. This process is called Binary Fission.
Much less frequently, the nucleus divides into three fragments, where the size of the third
fragment varies between a ‘scission neutron’ and a fragment similar in size to other two
fragments. This process is called Ternary Fission.
Fission can occur either spontaneously, or by the capture of an incident particle. In
spontaneous fission, the nucleus exists in a deformed state and with a potential energy highenough to allow tunneling through the potential fission barrier. In the case of capture, aparticle is absorbed forming a highly excited nucleus which then undergoes deformation.
For further detail see Hyde [1] and Feather [2].
Compare: Reaction Mechanisms.
Binary Fission
REACTION Coding: The fission process is coded using the process code F in SF3.
Example: (…(N,F),,SIG) Neutron fission cross section
Special rules apply for the coding of the Reaction Product (see EXFOR Manual Chapter 6:).
Spontaneous Fission is specified by coding 0 (zero) in reaction SF2 (incident projectile).
Example: (98-CF-252(0,F),,NU) Spontaneous fission for 252Cf
Fission Fragments. For quantities related to the bulk of heavy or light fission products, thecodes HF (heavy fragment) and LF (light fragment) are used in reaction SF7 (particle
considered); the code FF is used for quantities that apply to both heavy and light fragments.
Example: (…(N,F),,AKE,HF)

November 2005

Average kinetic energy of heavy fragments

F.1

LEXFOR

Fission (continued)
Fission Asymmetry. In the case of binary fission where the fission nucleus divides with highprobability into two unequal fragments, the ratio of the mean mass of the heavier fission
fragment to that of the light fission fragment is called the fission asymmetry.
See also Fission Yields.
REACTION Coding: ((…(N,F),,AP,HF)/(…(N,F),,AP,LF))
Ternary Fission
REACTION Coding: TER in SF5 (branch).
Example:(…(N,F),TER,SIG)(…(N,F),TER,DA,LCP)

Ternary fission cross section
Angular distribution of light charged particle in ternary
fission1

Frequently, the ternary fission is further specified by the accompanying light particle, e.g. 
particle accompanied ternary fission. Such information should be coded by specifying thelight particle in reaction SF4.
Example: (N,F)2-HE-4,TER,SIG) Cross section for DFFRPSDQLHGWHUQDU\ILVVLRQ
The ratio of binary to ternary fission may be coded using the codes BIN and TER inreaction SF5 (branch) and the code RAT in SF6 (data type).
Example: (…(N,F),BIN/TER,SIG/RAT)
Partial fission cross sections
The fission cross section is a sum cross section, for example:(n,f) = direct fission2 + (n,n'f) + (n,2nf) + …
the partial fission cross sections are coded under the keyword REACTION as follows:(n,n'f)(N,N+F),SEQ,SIG(n,2nf)(N,2N+F),SEQ,SIG(N,G+F),SEQ,SIG(n, f)

References[1.] E.K. Hyde, The Nuclear Properties of Heavy Elements, Vol. III (Prentice Hall, 1964).
[2.] N. Feather, Ternary Fission, Physics and Chemistry of Fission, Vienna, 1969
(I.A.E.A., 1969) p. 83.

1This is a partial cross section for those ternary fissions accompanied by the light charged particle specified.
For the coding of a direct fission cross section, a new branch code (e.g., DIR) could be introduced for SF5 assoon as such a case occurs and is to be coded in EXFOR.

2

F.2

November 2005

LEXFOR

Fission-Neutron Spectra(See also Delayed Fission Neutrons).
TheoryFission-neutron spectrum data are fitted either to a Maxwellian, a Watt, or a Madland-Nix
spectrum or to one of several other defined spectra.3
The Maxwellian spectrum4 has the shape:−

E

N (E) = Ee T
where

E is the energy of the fission neutron
T is the spectrum temperature given in MeV.
Also often given are the average kinetic energy E and the most probable energy Ep which aredefined as:
3T
E=

2
T E
Ep = =
2 3

The Watt spectrum5 is based on the assumption that fragments emit neutrons with a−2N ( E ) ≈ e T sinh
EE f 
T
Maxwellian spectrum in the center-of-mass system. The shape of the Watt spectrum is:where T is the spectrum temperature given in MeV but deviating from thetemperature defined in the Maxwellian fit;
Ef is a theoretical fragment kinetic energy per nucleon.
E

The average kinetic energy E is defined as:

E = Ef +3T
2

The Madland-Nix spectrum6 has the shape1[ fn(E , EHF ) + fn(E , ELF )]2
E is the energy of the fission neutron
EHF , ELF are the average kinetic energy per nucleon of the heavy and lightfragments
N (E) ≈

where

The numerical value of E should be approximately the same disregarding the spectrum shapeto which the data were fitted.
3

The Maxwellian and Watt spectra are considered as only rough approximations; a Double Watt Spectrum ispreferred. The 252Cf spectrum, which is more accurately known, suggests that none of the presently-used fits issufficient.
4
See Terrell [1].
5
See Watt [3].
6
See Madland [4]. See this reference for a complete definition of the spectrum.

November 2005

F.3

LEXFOR

Fission-Neutron Spectra (continued)
Fission spectrum average cross sections are defined as:σ=∫σ ( E ) N ( E ) EdE∫ N ( E ) EdE

Data to be compiled in EXFOR
1. Energy spectra of fission neutrons∫ X ( E )dE = 1
The energy spectrum in the normalized form is given by:where: E is the fission neutron energy,
X(E) is the spectrum.
REACTION coding: Process code DE in SF6, particle considered code N in SF7.
Units: a code from Dictionary 25 with the dimension 1/E (e.g., 1/KEV)
Data are also often given in arbitrary units, which require the REL modifier in the reaction
code.
Examples:(…(N,F),PR,DE,N)(…(N,F),DL,DE,N)(…(N,F),DL/PAR,DE,N)

Energy spectrum of prompt fission neutrons
Energy spectrum of delayed neutrons
Energy spectrum for a specific delayed-neutron group

Details of the fit and of the spectrum shape assumed should be given under the keyword
ANALYSIS.
2. Average kinetic energy of fission neutrons
It is also desirable to compile mean-energy values because they are rather independent of thespectrum shape assumed and frequently needed for measurement analysis (detector response,etc.).
REACTION coding: Process code AKE in SF6, particle considered code N in SF7.
Units: a code from Dictionary 25 with the dimension E (e.g., KEV)
Example:(…(N,F),PR,AKE,N)

F.4

Average kinetic energy of prompt neutrons

November 2005

LEXFOR

Fission-Neutron Spectra (continued)
3. Fission-neutron spectrum averaged cross sections, that is, data for an incident beamcomposed of a fission-neutron spectrum.
REACTION coding: modifier FIS in SF8.
It should be evident in the EXFOR entry whether the data were:• measured directly. The method should be specified under the keyword METHOD. The
kind of spectrum and the nuclide and incident-projectile energy from which the fissionneutron spectrum is produced should be specified under the keyword INC-SPECT.
• calculated by integrating a measured cross-section curve over an assumed fission-neutron
spectrum. This is specified using the code DERIV in REACTION SF9. An entry should
also be made under ANALYSIS. It is essential to give the assumed spectrum type and its
parameters, as well as how the fit was made (e.g., in a N(E)-versus-E scale or in a N(E)/Eversus-E1/2 scale.
See Spectrum Average for specification of incident spectrum.

References[1.] J. Terrrell, Fission Neutron Spectra and Nuclear Temperature, Phys. Rev. 113, 527(1959).
[2.] A. B. Smith, Fission Neutron Spectra: Perspectives and Suggestions Prompt Fission
Neutron Spectra, Proc. Consultants’ Meeting, Vienna, 1971 (I.A.E.A., 1972) p. 3.
[3.] B. E. Watt, Phys. Rev. 87, 1037 (1952).
[4.] D. G. Madland and J. R. Nix, Nucl. Sci. Eng., 81, 213 (1982).

November 2005

F.5

LEXFOR

Fission Yields(See also Fission).
TheoryThe fragments formed at the scission stage by a nucleus undergoing fission are called
primary, initial, or pre-neutron emission fragments.
The primary fragments repel each other, obtain their full kinetic energy (e.g., 90 MeV), emit
prompt neutrons (<4x10-14 sec) and gamma rays (<10-11 sec), are slowed down in thesurrounding medium, and stopped. These fragments are called secondary fragments, postneutron-emission fragments, or primary fission products WKH HPLWWHG UD\V PD\ FDXVH
conversion VDQG;UD\V 
The secondary fragments XQGHUJR DIWHU  VHF DQG PRUH  D VHULHV RI GHFD\V IRUPLQJ
secondary products, and end up in stable nuclei. For certain products the emission ofdelayed neutronsFRPSHWHVZLWK GHH[FLWDWLRQERWKIROORZLQJWKH GHFD\SURFHVV,QPRVW
of these stages mass yields and charge dispersions are measured as well as energy
distributions.
The terms fragments and products are not clearly distinguished. Most frequently the borderline between fragments and products varies, and often the word fragments is used as an
overall term, including all stages of decay.
Fission fragments are often specified only by their mass, including all Z-numbers, so that the
IUDJPHQW\LHOGUHPDLQVFRQVWDQWGXULQJ GHFD\)LVVLRQSURGXFWVDUHXVXDOO\VSHFLILHGE\Z
and A. A specified fission product is obtained in two ways: either immediately from fission(primary yield) or from the decay of another fission product. Thus, the total amount of a
specified fission product varies with time. Very short-lived fission products may,nevertheless, be most important, because some have extremely high capture cross sections(106 b). Finally, all decay to stable end products, partially via metastable states. For odd Anumbers, only one stable end product exists that is significantly formed in fission; for evenA-numbers, one or two exist.
The sum of the yield for all fission products will, in
general, add up to 200%, i.e., 100% for each of the heavy
and light product distributions (see example in figure7).
Since in ternary fission more than two fragments areformed per fission, the yields for all fragments sum up to a
bit more than 200%.
For further information, see Pappas [1] and Walker [2].

7

Takn from R.L. Walsh et al., Physics and Chemistry of Fission, Proceedings of a Symposium, Juelich, 1979
(I.A.E.A., 1980) p.129.

F.6

November 2005

LEXFOR

Fission Yields (continued)
Coding:1. Absolute Yields. (Fissions and fission fragments are counted independently.)
REACTION coding: The quantity code FY in SF6. The yield type is specified in SF5(Branch) (see under specific type of yield, following pages).
Units: a code from Dictionary 25 with the dimension FY (e.g., PC/FIS).
2. Relative yields.
REACTION Coding: same as above with modifier REL in SF8
Units: ARB-UNITS
However, emission of light particle in ternary fission does not change the sum of yields in thebinary fission mass range usually measured, and other mass splits in ternary fission are
negligible, therefore, relative yield measurements may be normalized to 200% if themeasurement was made for a sufficient large number of fragments. If this is done, the datatable may include some values that have not been measured but obtained by interpolation;such values must be labeled by flags.
The fission product considered is coded either in REACTION SF4 or as a variable in the datatable.
Examples for product nuclei coded within the reaction code:(92-U-235(N,F)54-XE-124,IND,FY) independent yield of the fission
product 124Xe(92-U-235(N,F)54-XE-133-G,CUM,SIG) cumulative production crosssection for the fission product 133gXe
for coding product nuclei as variablesin the DATA tables:(92-U-235(N,F)ELEM/MASS,IND,FY)independent yield of specified productnuclei which are given in the DATA
table under the data headings
ELEMENT, MASS, and ISOMER (ifapplicable).
(92-U-235(N,F)MASS,CHN,FY) chain yield of several mass numbers given in
the DATA table under the data
heading MASS.
See Reaction Product and EXFOR Manual Chapter 6: Variable Nucleus for details.
Yield data to be compiled in EXFOR
1. Primary fission-fragment yield. The primary yield per fission of fission-fragment mass
A before prompt neutron emission. It may also be called pre-neutron-emission fragmentmass distribution. In all experimental techniques corrections for some prompt neutrons
already emitted cannot be avoided.

November 2005

F.7

LEXFOR

Fission Yields (continued)
REACTION coding: Branch code PRE in SF5.
Example:(....(N,F)ELEM/MASS,PRE,FY)

2. Secondary fission-fragment yield. The secondary yield per fission of fission-fragment
PDVV$DIWHUSURPSWQHXWURQHPLVVLRQEXWEHIRUH GHFD\DQGGHOD\HGQHXWURQHPLVVLRQ,W
may also be called post-neutron-emission fragment-mass distribution.
REACTION coding: Branch code SEC in SF5.
Example: (....(N,F)MASS,SEC,FY)
3. Independent fission-product yield. The direct or independent yield per fission of a
primary fission product specified by Z and A; i.e., after prompt neutron emission, but before
 GHFD\ DQG GHOD\HGQHXWURQ HPLVVLRQ LQFOXGLQJ RQO\ WKH GLUHFW \LHOG DQG QRW WKH \LHOG
obtained from decay of other fission products.
REACTION coding: Branch code IND in SF5.
Example: (…(N,F)ELEM/MASS,IND,FY)
Sum rule: The secondary yield is equal to the sum, over all Z (for one A) of the independent
yields.
Experimental data for independent yields of the product Z,A include yields from the delayedneutron emission of the product Z,A + 1 or from the beta decay of the product Z-1,A, if
separation times are not short against the relevant decay times. Corrections are required andshould be mentioned under the keyword CORRECTION. Fragment-mass yields are notaffected by beta decay but only by delayed-neutron emission.
4. Cumulative fission-product yield: the cumulative yield per fission of a secondary fission
product specified by Z and A, i.e., after prompt-neutron emission, and including theindependent yield plus the yield from decay of other fission products.
REACTION coding: Branch code CUM in SF5.
Example: (…(N,F)ELEM/MASS,CUM,FY)
Sum rule:

CUM,FYIRUWKH GHFD\LQJSURGXFW=$IND,FY for product Z,A =CUM,FY for product Z,A, if the products Z-1,A and Z,A+1 are not delayedneutron emitters.

The following events may add to the cumulative yield of the fission-product Z,A in its groundstate:• independent yield from fission• GHFD\IURPSURGXFW=$LQJURXQGVWDWH• GHFD\IURPSURGXFW=$LQDPHWDVWDEOHVWDWH• delayed-neutron emission from product Z,A + 1• internal transition from a metastable state of product Z,A

F.8

November 2005

LEXFOR

Fission Yields (continued)
In addition, the product Z,A may be formed from neutron capture in the product Z,A-1; thisproduct is not included in the "cumulative yield".
The cumulative yield is often given for an isomeric state of a fission-product Z,A; the isomeris entered in EXFOR as a separate data field, see EXFOR Manual Chapter 6: Variable
Nucleus.
5. Total chain yield. The total chain yield per fission of fission-fragment mass A is the sumof the cumulative yields of all stable fission products having the same mass A. When only
one stable fission product per mass A exists, the total chain yield for mass A is identical withthe cumulative yield of the stable end product Z,A.
REACTION coding: Branch code CHN in SF5.
Example: (…(N,F)MASS,CHN,FY)
6. Total mass yield The total mass yield per fission of fragment mass A is the sum of the
independent yields of all fission products with the mass A.
REACTION coding: Branch code MAS in SF5.
Example: (…(N,F)MASS,MAS,FY)
7. Fractional yields The distribution of charge Z within a given fragment mass chain A iscalled charge dispersion. It can empirically be approximated by a Gaussian distribution witha most probable charge Zp (see following).
The fractional independent yield of a fission product (after prompt neutron emission) is givenby:[

P ( Z ) = ( cπ ) −1 / 2 exp − ( Z − Z p ) 2 / c]whereas the fractional cumulative yield is given by
Z

1
Pn =
∑
σ 2π
n =0

Z +1 / 2∫ e − ( n − Z p )2 


2
 2σ


dn

−∞

7KHSDUDPHWHUVFDQG DUHZLGWKVRIWKHGLVWULEXWLRQVUHODWHGE\c ≈ 2 (σ 2 + 1 / 12 )For charge dispersion, fractional yields are defined only as ratios to total chain yield.
For further information, see Wahl [3].
REACTION coding: coded as an explicit ratio, and followed by the keyword RESULT.
In all cases, the data are entered as ratios with values from 0 to 1 and data units NO-DIM.

November 2005

F.9

LEXFOR

Fission Yields (continued)
Examples:a.)

REACTIONb.)

RESULT
REACTIONRESULT((92-U-235(N,F)ELEM/MASS,IND,FY)/(92-U-235(N,F)MASS,CHN,FY))(FRIND)((92-U-235(N,F)ELEM/MASS,CUM,FY)/(92-U-235(N,F)MASS,CHN,FY))(FRCUM)

8. Most probable charge. The most probable initial charge Zp for a given mass chain.
REACTION Coding: the process code ZP in SF6
Example: (…(N,F)MASS,,ZP)
Note: The Gaussian width parameter is assumed to be approximately constant for all A
chains, as given by Wahl, et al. Therefore Zp has sometimes been determined from a single
IUDFWLRQDO \LHOG PHDVXUHPHQW  +RZHYHU WKHUH LV HYLGHQFH IRU D YDULDWLRQ RI F DQG  ZLWK
mass A, and they may be determined together with Zp. Therefore, the Gaussian widthparameter used should be explained (value or reference).
9. Most Probable Mass. The most probable mass Ap is the mean mass for a given element.
REACTION Coding: AP in SF6
Example: (…(N,F)ELEM,,AP)
10. Charge yields. The charge yield (or elemental yield) is defined as the sum of the
independent yields for all products with a specified Z.
Definition: Charge distribution (primary charge function) is defined as the distribution ofprimary charge about Zp as a function of primary mass.
This quantity is deduced, either from other quantities (charge dispersion, mass distribution),or from instrumental measurements of fragment mass (kinetic energy) and X-rays; bothmethods involving uncertain corrections for prompt-neutron emission.
REACTION Coding: Branch code CHG in SF5.
Example:(……(N,F)ELEM,CHG,FY)

10. R-values. An R-value is a ratio of measurement results for 2 different energies or energy
spectra (one of which is considered to be a monitor reaction), each of which is relative to thesame standard reaction.
REACTION Coding: coded as an explicit ratio, followed by an entry under RESULT withthe code RVAL.
Example:REACTIONRESULT

F.10(((92-U-238(N,F)ELEM/MASS,CUM,FY,,FIS)/(92-U-238(N,F)42-MO-99,CUM,FY,,FIS))//((92-U-238(N,F)ELEM/MASS,CUM,FY,,MXW))(92-U-238(N,F)42-MO-99,CUM,FY,,MXW)))(RVAL)

November 2005

LEXFOR

Fission Yields (continued)
Yields of correlated fragment pairs
The Z and A of the correlated pair are entered under the field headings ELEM1, MASS1, and
ELEM2, MASS2.
1. Yields of correlated fragment pairs.
REACTION coding:: Process code FY/CRL in SF6.
Example:BIB
REACTION…
ENDBIB
COMMONELEM1NO-DIM
56.
ENDCOMMON
DATA
MASS1
NO-DIM
138.
138.
…
ENDDATA(…(N,F)ELEM/MASS,IND,FY/CRL)ELEM2NO-DIM
42.

MASS2
NO-DIM
104.
105.
…

DATA
PC/FIS…
…
…

2. Kinetic energy of correlated fragment pair.
The total kinetic energy of the fragment pair is given.
REACTION coding: Process code KE/CRL in SF6.

References[1.] A. C. Pappas, J. Alstad, and E. Hagebo, Mass, Energy, and Charge Distribution in
Fission, Physics and Chemistry of Fission, Symposium, Vienna, 1969 (I.A.E.A.,
1969), p. 669[2.] W. H. Walker, Status of fission product yield data for thermal reactors, Fissionproduct Nuclear Data, IAEA Panel, Bologna, 1973, report IAEA-169, Vol. I, (1974) p.
285[3.] A.C. Wahl, et al., Nuclear Charge Distribution in Low-Energy Fission, Phys. Rev. 126,
1112 (1962)

November 2005

F.11

LEXFOR

Fitting Coefficients
Coefficients obtained from a fit to a differential cross section may be coded into EXFOR byentering the type of expansion used to fit the data in REACTION SF8 and specifying therepresentation used.
The data for a given energy is entered with the coefficient number given under the data
heading NUMBER or NUMBER-CM (compare Center-of-Mass System).
Where the first coefficient (l=0) is either unity or another constant, it need not be coded in thedata table.
Where the first coefficient is identical to the cross section, it should be coded as a separate
subentry. Each subentry should have a cross-reference under STATUS to the other subentry,
using the code COREL.
Example:STATUS(COREL,10234002) ZEROTH ORDER COEFFICIENT * 4PI
GIVEN AS ELASTIC SCATTERING CROSS SECTION

Note: If the directly measured differential cross sections are also coded in EXFOR, thefitting coefficients need not be compiled. If compiled, the coefficients should be marked
as dependent data under STATUS, with a cross-reference to the subentry number of thecross section from which they were derived.
Expansions to be coded into EXFOR
The following pages contain examples of data to be coded in EXFOR. For a complete list of
the fitting coefficient codes, see Dictionary 36.
1. Cosine Coefficients: coefficients obtained by fitting a differential cross section using anequation containing a sum in powers of cosine.
REACTION Coding: COS in SF8 plus a code indicating the representation used.
Representations:
DA,,COS= al (unit type DA, e.g., B/SR) where:ndσ( E , θ ) = a0 + ∑ al ( E ) cos l θdΩl =1DA,,COS/RS= al (units NO-DIM) where:
n
dσ
σ 

( E ,θ ) =1+a l ( E ) cos l θ ∑dΩ
4π  l =1


F.12

November 2005

LEXFOR

Fitting Coefficients (continued)
DA,,COS/RS0 = al (units NO-DIM) where:ndσdσ( E ,θ ) =( E ,0°)∑ al ( E ) cos l θ
dΩ
dΩ
l =1
DA,,COS/RSD = al (units NO-DIM) where:ndσdσ( E ,θ ) =( E , 90°) ∑ al ( E ) cos l θ
dΩ
dΩ
l =1
DA,,COS/1K2= al (units NO-DIM) where:dσ
1 n( E ,θ ) = 2 ∑ a l ( E ) cos l θdΩ
k l =0k = wavenumber

2. Legendre Coefficients
Definition: Coefficients obtained by fitting a differential cross section using an equation
containing a sum of Legendre polynomials.
REACTION Coding: LEG in SF8 plus a code indicating the exact representation used.
Representations:
DA,,LEG= al (unit type DA, e.g., B/SR) where:ndσ( E ,θ ) = a 0 + ∑ a l ( E ) Pl (cos θ )dΩl =1DA,,LEG/RS= Wl (units NO-DIM) where:
n
dσ
σ 

( E ,θ ) =1+
Wl ( E ) Pl (cos θ )∑dΩ
4π  l =1
DA,,LEG/RSL = Bl (units NO-DIM) where:
n
dσ
σ 

( E ,θ ) =1( 2l + 1) Bl Pl (cos θ )+∑dΩ
4π  l =1
DA,,LEG/RS0 = Bl (units NO-DIM) where:ndσdσ( E ,θ ) =( E , 0°)∑ al ( E ) Pl (cos θ )
dΩ
dΩ
l =1

DA,,LEG/RSD = Bl (units NO-DIM) where:ndσdσ( E ,θ ) =( E , 90°) ∑ al ( E ) Pl (cos θ )
dΩ
dΩ
l =1

November 2005

F.13

LEXFOR

Fitting Coefficients (continued)
DA,,LEG/2L2 = al (unit type DA, e.g., B/SR) where:dσ
1 n( E ,θ ) = ∑ ( 2l + 1)a l ( E ) Pl (cosθ )dΩ
2 l =0

DA,,LEG/L4P (deleted, never used)
DA,,LEG/1K2 = al (units NO-DIM) where:dσ
1 n( E , θ ) = 2 ∑ al ( E ) Pl (cos θ ) k = wavenumberdΩk l =03. Associated Legendre Polynomials of the First Kind
Definition: Coefficients obtained by fitting• a differential (with respect to angle) cross section or polarization• or the product of a differential polarization and a differential cross section• or the product of a differential polarization and the square of a differential cross section
using an equation containing a sum of associated Legendre polynomials of the first kind (see,for example, Chapter 8 of Abramowitz [1] for the relationship between Legendre functions).
See also Polarization.
REACTION Coding: AL1 in SF8.
Representations:
FM/DA,,AL1= al (unit type DA, e.g., B/SR) where:P ( E ,θ ) ×ndσ( E ,θ ) = ∑ a l ( E ) Pl1 (cos θ )dΩ
l =0FM2/DA,,AL1 = al (unit type DA, e.g., B/SR) where:ndσ 2( E ,θ ) = ∑ a l ( E ) Pl1 (cos θ )P ( E ,θ ) ×
dΩ
l =0

F.14

November 2005

LEXFOR

Fitting Coefficients (continued)
4. Sine-Squared Coefficients
Definition: Coefficients obtained by fitting• a differential (with respect to angle) cross section or polarization• or the product of a differential polarization and a differential cross section• or the product of a differential polarization and the square of a differential cross section
by an equation containing a sum in powers of sine. (See also Polarization).
REACTION Coding: SN2 in SF8.
Representations:
FM/DA,,SN2= al (unit type DA, e.g., B/SR) where:P ( E ,θ ) ×ndσ( E ,θ ) = ∑ a l ( E ) sin 2 l θdΩl =0FM2/DA,,SN2 = al (unit type DA, e.g., B/SR) where:ndσ 2
P ( E ,θ ) ×( E ,θ ) = ∑ a l ( E ) sin 2 l θdΩ
l =0

4. Cosine-Squared Coefficients
Definition: Coefficients obtained by fitting a differential cross section using an equation
containing a sum in powers of cosine.
REACTION Coding: CS2 in SF8.
Representations:
DA,,CS2= al (unit type DA, e.g., B/SR) where:dσ( E ,θ ) = a0 + a1 sin 2 θ + a2 sin 2 θ cos θ + a3 sin 2 θ cos 2 θdΩ
Note: The 1st and 2nd terms are equal to the sine2 expansion.

Reference:[1.] M. Abramowitz and I.A. Stegun, Handbook of Mathematical Functions, Dover
Publications, 1970.

November 2005

F.15

LEXFOR

Flags
Flags are used to link information in the BIB section to specific lines in the DATA section.
The flags are given as fixed point numbers (compare, EXFOR Manual, page 4.2) and codedin the data table with the units NO-DIM . There are, currently, three types of flags in use in
EXFOR.
Data Heading FLAG: Flags are used to link free-text comments in the BIB section with oneof more lines in the data table
The meaning of the flags is given under the information-identifier keyword FLAG, where theactual flags are given in parenthesis, each on a separate line, starting in column 12, followed
by a free text comment. (See EXFOR Manual Chapter 7: FLAG). . These flags are repeatedunder the data heading FLAG. There may be more than one field with the heading FLAG (seeEXFOR Manual Chapter 4: Multiple representations of independent variables).
FLAG should not, in general, be used for entire sub-works or for one-line data tables. An
exception would be where the BIB-information is given in the common subentry (SAN=1)
and for some, but not all, of the following subentries, a flag world be used in a one line datatable. (All flags given in the common subentry must be used in all data subentries.)
The data heading FLAG may not be used in the COMMON section.
Example:BIB…
FLAGENDBIBNOCOMMON
DATA
DATA
MEV
756.
876.
ENDDATA(1.) Resonance assignment uncertain(2.) Spin assignment uncertainDATA
MILLI-EV
0.
1.

FLAG
NO-DIM
1.
2.

Data Heading DECAY-FLAG: Flags are used to link coded information on decay data in the
BIB section with one or more lines in the data table.
The flags are given under the information-identifier keyword DECAY-DATA DATA (seeEXFOR Manual Chapter 7: DECAY-DATA) or RAD-DET (see EXFOR Manual Chapter 7:
RAD-DET) as the first field of the coded information, enclosed in parenthesis. These flags
are then repeated in the DATA section under the data heading DECAY-FLAG.
(See also Decay Data).

F.16

November 2005

LEXFOR

Flags (continued)
Example:BIB…
DECAY-DATA
ENDBIB…
DATA
ELEMNO-DIM
60.
60.
ENDDATA((1.)60-ND-138,5.04HR,DG,328.,0.65)((2.)60-ND-141,2.49HR,DG,……………………)MASS
NO-DIM
138.
140.

DATA
PC/FIS…
…

DECAY-FLAG
NO-DIM
1.
2.

Data Heading LVL-FLAG: Flags are used to link coded information on level properties in
the BIB section with one or more lines in the data table.
The flags are given under the information-identifier keyword LVL-PROP (see EXFOR
Manual Chapter 7: LEVEL-PROP) as the first field of coded information, enclosed inparenthesis. These flags are repeated in the DATA section under the data heading LVLFLAG.
Example:BIB…
LEVEL-PROP
ENDBIB
…
DATA
E-LVL
MEV
0.
0.803
ENDDATA

November 2005((1.)82-PB-206,E-LVL=0.,SPIN=0.,PARITY=+1.)((2.)82-PB-206,E-LVL=0.803,SPIN=2.,PARITY=+1.)

DATA
MB
…
…

LVL-FLAG
NO-DIM
1.
2.

F.17

LEXFOR

Free Text(See also EXFOR Manual Chapter 3).
Be short and precise!
The language of the free text is English. The free text should be clear enough so that users
who are not familiar with the system, can easily understand it; no abbreviations should be
used that are not self-explanatory, and no codes from dictionaries should be used in the freetext. The text may include any character from the permitted character set; see EXFOR
Manual, page 1.3. (For general rules see EXFOR Manual Chapter 3: Free Text).
Some examples:••••

Write Nucl.Phys., and not NP
Write % or percent, and not PC
Separate a number and its unit by a blank for clarity.
Element symbols and their A values may be written as, e.g., 235U; the Z value can beomitted. For natural elements only the symbol should be used, e.g., Fe.

Names of journals or other names should not be translated into English. Write "Yadernaya
Fizika", and not "Nuclear Physics" which applies to another journal.
When writing formulas in free text, the compiler should attempt to use the FORTRAN
conventions when they apply with liberal use of parentheses for clarity.
Free text information should be entered under the keyword to which it pertains. For example,
comments which refer to any of the REACTION subfield codes or which are necessary tounderstand a special coding or reaction type, should be given in the free text under
REACTION rather than under COMMENT.
In general, the contents of the coded information should not be repeated in free text, since thecoded information is either self-explanatory, as in the case of AUTHOR, or the codes aredesigned for machine processing. For others, the compiler may indicate, whether the code isexpanded in the free text.
Standard values, parameters and other numerical values should, if suitable be entered in the
DATA or COMMON section, although they maybe also given in free text.
Free text following codes can start right after the closing parenthesis; however, for clarity, it
may be indented. Blank lines should be used with discretion.
Parentheses "( )" can be used in the free text except in column 12 where the opening
parenthesis marks a code. Continuation lines may start in column 12, however, beginning
continuation lines after column 12 is good coding practice, as it eliminates the accidental
coding of a parenthesis in this column.
Free text comments not originating with the author must be clearly labeled, e.g., "(commentby the compiler)"’, and unambiguously separated from authors comments, e.g., by including it
between quotation marks. See also Comment.

F.18

November 2005

LEXFOR

Gamma Spectra(See also Partial Reactions).
Data to be compiled in EXFOR
1HXWURQ FDSWXUH UD\ VSHFWUD ZHUH QRW JLYHQ KLJK SULRULW\ LQ WKH SDVW VR GDWD FRPSLODWLRQ
was not required until 2004.
1. ,QWHQVLWLHVRI OLQHVREACTION coding: SPC in SF6 (Process).
Example: (…(N,G)…,,SPC)
Units: code from Dictionary 27 with the dimension SPC (e.g., GAM/100N)
The γ-ray energies are discrete values coded under the data heading E.
Relative measurements require the addition of the REACTION modifier REL and units ARBUNITS.
2. Continuous spectra of unresolved

V

REACTION coding: DE in SF6 (Process).
Example: (…(N,G)…,,DE)
Units: code from Dictionary 27 with the dimension DE (e.g., MB/MEV)
7KH UD\HQHUJ\LVDFRQWLQXRXVYDULDEOHFRGHGHLWKHUDVDUDQJHZLWKGDWDKHDGLQJVEMIN and E-MAX, or with the mid-point of the energy bin given under the data heading E andthe bin width given under E-RSL.
3. Partial radiation widths
REACTION coding: WID in SF6 (Process), PAR in SF5 (Branch).
Example: (…(N,G),PAR,WID)
Units: code from Dictionary 27 with the dimension E (e.g., EV)
The secondary energy variable coded is:• HLWKHUWKH UD\HQHUJ\FRGHGXQGHUWKHGDWDKHDGLQJE,• or the final level energy, coded under the data heading E-LVL-FIN,• or the initial and final energy, coded under the headings E-LVL-INI and E-LVL-FIN.

November 2005

G.1

LEXFOR

General Quantity Modifiers
The list of general quantity modifiers (REACTION SF8) is given in Dictionary 34. They canbe added to any quantity without requiring an entry in Dictionary 36. Some of them requireclarification:
1. RAW modifier: used for raw or uncorrected data such as reaction yields, raw gamma
spectra, etc.
The modifier RAW must not be used for data for which specific codes have been introduced,
e.g., for transmission data. (See Raw Data).
2. FCT modifier: used when the data has been multiplied by a defined factor not containing
another quantity (e.g., an arithmetic factor or a branching ratio). Explanatory free text is
compulsory. If the factor contains another quantity, the appropriate reaction combination is
to be used, except in the case of a ratio of the same quantities (see REL modifier).
The modifier FCT must not be used for factors for which specific codes have been introduced(such as isotopic abundance; see item 5, below). (See Products).
3. REL modifier: used in the case of shape normalized data, that is, data proportional to thequantity given; the normalization factor is unknown. The data unit ARB-UNITS (arbitrary
units) should be used.
The REL modifier always needs explanation in free text.
An explicit ratio defined under the REACTION keyword does not require the modifier REL
and will usually have the units NO-DIM. (See Ratios).
4. MSC modifier: used for unusual data types, indicating that the exact definition of thequantity is given in free text following the REACTION code. This modifier should be usedwith discretion because the data will not be fully machine-retrievable.
5. A modifier: used when a measured is made on a target of natural isotopic abundance andthe reaction which produces the reaction product specified is known, but the data have notbeen corrected for the natural abundance of the target nuclide. The modifier (A) is used if thecompiler is uncertain whether the data have been corrected for natural abundance of the target
nuclide.
6. AV modifer: used for data measured as a function of energy or angle and averaged over agiven energy interval or angular range.
7. Spectrum average modifiers: used for data measured over a broad incident energy
spectrum. For such data one of the spectrum modifiers are used BRA, BRS, EPI, FIS,
FST, MXW, and SPA; see Spectrum Average for details.
8. TT modifier used for data averaged over energies through a thick target, see Thick/Thin
Target Yields.

G.2

November 2005

LEXFOR

Half-lives
Half-life values in EXFOR entries may define an isomeric state, or they may be basic
parameters for deducing the data value from the experiment.
Half-lives may be coded in one of the following ways.
1. In the BIB section using the keyword DECAY-DATA (see Decay Data). This is thepreferred method for the following:• for metastable states in all nuclei involved in a reaction,• for the ground state of any radioactive nuclei involved in the reaction when its half-life
is an essential parameter in the analysis of the experimental data.
2. When the half-life is a variable for the data presented, e.g., delayed neutron groups, it must
be coded in the COMMON or DATA section using data headings from Dictionary 24 withthe family code 6, e.g., HL, HL11. These are linked to the BIB keyword HALF-LIFE (seebelow).
If more than one half-life is given, the relevant nuclei must be coded under this keyword. If
only one half-life value is given under the data heading HL with no explanation, then it refers
to the half-life of the residual nucleus.
Numerical uncertainties may be entered using data headings from Dictionary 24 with thefamily code 7, e.g., HL-ERR, with a free text explanation under ERR-ANALYS; see EXFOR
Manual, ERR-ANALYS.
Example:BIB
REACTION…
ENDBIB
COMMONHL
SEC…
ENDCOMMON(…(N,F),DL/GRP,NU)

DATA…

See EXFOR Manual Chapter 4 for the repetition of the data heading HL in coding half-lives
in different units.
Information-identifier keyword HALF-LIFE: used to explain to which nucleus a half-lifevalue given in the COMMON or DATA section refers. The coded information contains thedata-heading keyword used and the relevant nucleus. (See EXFOR Chapter 7: HALF-LIFE,for coding details).
The free text should include the source of the half-life value, if known.

1

For the decay of a nucleus, the use of DECAY-DATA is preferred.

September 2004

H.1

LEXFOR

History
The information-identifier keyword HISTORY is used to document the chronologicalhandling of the work within a data center. In particular, important corrections or revisions toan entry or subentry must be documented under HISTORY.
The coded information consists of a date and a one-character code, and is followed by freetext. (See EXFOR Chapter 7: HISTORY, for coding details; see Dictionary 15 for list ofcodes).
Important alterations are flagged with the code A in order to automate, as far as possible,
follow-up actions resulting from the alteration, such as informing users who have received anearlier version. The following items are considered sufficiently important to be flagged withthe code A:• any change in the numbers given under COMMON or DATA
• any change in the meaning of these numbers (e.g., due to change of reaction, units, thereaction under MONITOR, etc.)
Less important changes that the compiler wishes to document may be flagged by the code U.2
Examples of possible entries under the HISTORY keyword(19671119R)(19680220L)(19690411C)(19691015R)(19691223)(19701003T)

Data received from author on tape
Data entered into libraryAB
Data on tape ND 1234 from Ribon.3
Proof copy sent to author
Data converted from SCISRS-I, and checked foragreement with table 3 in Phys. Rev. 56, p. 784(19721130A) Some errors in data table corrected(19721130U) Spelling error in BIB corrected
The rules concerning BIB information apply to HISTORY, i.e., an entry under history in thecommon subentry (SAN=1) applies to all other subentries and should not be repeated in thedata subentries.

2

Compilers are urged to document all changes under HISTORY
The origin of the numerical data may be given here or under STATUS.
4
For data converted from another data library, see also Status.
3

H.2

September 2004

LEXFOR

Incident Beam Source(See also Polarization)
Data heading Keyword INC-SOURCE
This keyword is used exclusively for the nuclear reaction used as an incident- projectile
source. The apparatus in which this reaction took place is entered under FACILITY, and thequality of the resulting particle beam is entered under INC-SPECT (see Incident-Projectile
Energy). (For certain cases, e.g., when the neutron source is a reactor, the use of the
keywords INC-SOURCE and FACILITY is somewhat overlapping.)
In general, the coded information is a code taken from Dictionary 19.
Photon Sources
The source codes for photons are divided into three categories, which may be used in
combination:
1. The spectrum type, e.g., monoenergetic, quasi-monoenergetic, or Bremsstrahlung.
2. The spectrum type, e.g., hardened, tagged, etc.
3. The source, e.g., laser, Compton scattering, etc.
Examples:INC-SOURCE (QMPH,ARAD)
INC-SOURCE (BRST,HARD)
INC-SOURCE (MPH,LASER)

Quasi-monoenergetic
photons
obtainedannihilation radiation.
Hardened Bremsstrahlung spectrum.
Monoenergetic radiation from Laser scattering.

from

For monoenergetic photons resulting from reactions that do not have a code given in
Dictionary 19, use the code MPH, followed by an equal sign (=) and the source reaction.
Example:INC-SOURCE (MPH=(24-CR-52(N,G)24-CR-53)

November 2005

I.1

LEXFOR

Incident-Projectile Energy
See also Spectrum Average.
The energy of the incident projectile is entered in the COMMON or DATA section under theappropriate data heading (i.e., a data heading from Dictionary 24 having an a in column 66).
Compare: Secondary Particles, Secondary Energy.
The wave-length of an incident neutron corresponds to the neutron energy:
E(eV) =

0.0818Å) 2(Angstrom)
1.0
1.8
2.0
4.0
6.0
10.0

E(eV)
0.08180.02530.02050.00510.00230.0008It is entered under the data heading WVE-LN with units ANGSTROM1.
For data are averaged over an incident-neutron spectrum, see under Spectrum Average forenergy specification.
Information on the characteristics of the resolution and the spectrum of the incidentprojectile beam is entered in free text under the keyword INC-SPECT. (See EXFOR
Manual Chapter 7: INC-SPECT).
Nuclear Quantities
No incident energy is entered for nuclear quantities, i.e., data specified by REACTION SF2(incident projectile) = 0 (zero).
For nuclear properties such as the Nuclear Temperature, for which the incident-projectile
energy is not quite irrelevant, the energy may be given in free text but should not be enteredin the data table.

1

Older data sets may use the data heading EN.

I.2

November 2005

LEXFOR

Independent and Cumulative Data
The formation of a residual nucleus may occur:• By direct (independent) formation, and/or• Via isomeric transition,• Via radioactive decay from other nuclides.
For fission yields and isotope production data, the following codes are used to distinguishwhich of these processes are measured.
Branch Code
IND

CUM
(CUM)

M+
CUM/M-2(M)

Definition
Data are given for independent formation of the product nucleus. To beused only for fission yield data. For isotope production, independent
formation is the default value.
Data given includes the formation via radioactive decay and isomerictransition.
Data given are assumed by the compiler to include the formation via
radioactive decay and isomeric transition, but no definitive statement isgiven by the author.
Data given for an isomeric state includes formation by partial feeding via
isomeric transition from metastable states of higher excitation energy.
(See also Isomeric States).
Data given for the cumulative yield to an isomeric state excludes
formation by feeding via isomeric transition from metastable states ofhigher excitation energy.
Data given are assumed by the compiler to include the formation by
partial feeding via isomeric transition, but no definitive statement is givenby the author.

Examples:
REACTION(92-U-235(N,F)56-BA-140,IND,FY) Independent formation only.

REACTION(42-MO-0(P,X)27-CO-62-M,CUM,SIG) Cumulative cross section;

includes formation via decay of 68-sec. 62Fe and feeding from 13.91min. 62Co isomer.
REACTION(42-MO-0(P,X)27-CO-62-M,CUM/M+,SIG) Cumulative cross section;

includes formation via decay of 68-sec. 62Fe and only partial feedingfrom 13.91-min. 62Co isomer.
REACTION(42-MO-0(P,X)27-CO-62-G,CUM/M-,SIG) ) Cumulative cross sectionthat includes formation via decay of 68-sec. 62Fe, but excludes feedingfrom 13.91-min. 62Co isomer.

2

The code M- is used only in combination with the code CUM.

November 2005

I.3

LEXFOR

Independent Variables
Independent variables are identified by a Family Flag in Dictionary 24 (See Dictionary
Manual). A given set of independent variables are required depending on the Quantity givenin the REACTION string.3
Only those independent variable data headings specified in EXFOR Manual Chapter 4 may
be repeated (e.g., angles in degrees and minutes).
In general, the same values of a set of independent variables (e.g., energy, angle) will notoccur more than once. If there is a repetition of a measurement for a given independent
variable (e.g., at a given energy), the reason should be given in free text in the BIB section.
Otherwise, it may be interpreted as a data entry error or as an inadvertent duplication.
In the case the duplicated measurement is a function of two or more independent variables,
flags should be used to link those data given for the second (or third, etc.) variable.
Example:
BIB
…
FLAG
…
DATA
EN
MEV
1.
1.
1.
1.
1.
1.
…

(1.) First set of measurements(2.) Second set of measurements

ANG
ADEG
10.
10.
20.
20.
30.
30.

DATA
MB/SR
…
…
…
…
…
…

FLAG
NO-DIM
1.
2.
1.
2.
1.
2.

Flags should also be used in the case where data are a function of only one independent
variable, if it is known that the data were measured as two or more overlapping sets and thedata from each set can be identified. For example, data are often measured in two
experiments for different energy ranges with overlapping energy.
Note: Alternately, if data are measured in two experiments for different energy ranges andthe experimental conditions differ, the data may better be coded as separate data sets.

3

Which independent variables must be given for a given quantity is determined by the reaction type as given in
Archive Dictionary 36, and defined in Archive Dictionary 13.

I.4

November 2005

LEXFOR

Institute
The laboratories, institutes, or universities with which all authors are affiliated, is entered incoded form under the information-identifier keyword INSTITUTE. More than one
institution may be entered for a given work. (See EXFOR Manual Chapter 7: INSTITUTE,
for coding details).
The institutions may be entered:• with the one containing the facility entered as the first institute,• in the order in which they are given in the main reference,• with the institution from which one is most likely to obtain further information on theexperiment as the first institute.
Compilation Responsibility
If two or more institutions of different service areas are involved, the following rules shalldetermine the compilation responsibility. (See NRDC Manual, pages 2-3).
1. The institute of the facility used, if at least one author is from this institute. If an itinerantgroup used the facility, the main investigator of this group determines the center responsible.
2. If facilities of different laboratories from different service areas are used, the institution
from which it is most likely to obtain further information on the experiment should determine
the center responsible. This will normally be the corresponding author, or, in case of doubt,
the first author of the publication. In all such cases the other affected center and NDS must be
contacted before compilation to avoid duplication.
3. If separate experiments from different service areas with clearly separated results arereported in the same paper, the results should be compiled in separate entries. This separation
is obligatory for different projectile types (neutron, charged particle, photon). In all suchcases cross references to the other entry must be given.
If a publication reports the results of different experiments, done at different laboratories, or,measured at one laboratory, and, subsequently, analyzed at another laboratory, and either thelaboratories are in different areas, or the incident-projectile is of a different type (i.e., neutron,
charged particle, or photon), the results are compiled in separate entries by the center
responsible for the data. The entries may be linked using the STATUS code COREL; see
Status (Interdependent Data).

November 2005

I.5

LEXFOR

Isobaric Analog Resonances
Definitions
The energy levels of isobaric (equal A) nuclei are relatively insensitive toward theinterchange of a proton and a neutron. Given two isobaric nuclei (N,Z+1) and (N+1,Z), if T0
is the ground state isospin of nucleus (N+1,Z), its isobaric analog state in nucleus (N,Z+1)
will be the lowest state where T=T0. The isobaric analog state will have the same properties,
but will have a higher energy, δEC, because of the additional Coulomb energy associated withthe extra proton, less the neutron-proton mass difference.

(This region contains
many levels not shown in
the figure)

δEC
T1
T0
T′1
T′0
ET
N+1,Z

N,Z+1
where

T0 is the isobaric analog of the ground state T′0 of (N+1,Z),
T1 is the analog of the first excited state T′1, etc.
T0, T1, etc., are not necessarily adjacent levels.
ET is the excitation energy of the T = T0 state.

CodingIn the case where the experimentalist does not give the excitation energy of the isobaric
analog state, the level number of the (N+1,Z) nucleus for which the isobaric analog state isgiven may be entered in the data section using the field heading IAS-NUMB, and the spin andparity, if given, may be specified under the keyword LEVEL-PROP.
Example: LEVEL-PROP(23-V-46,IAS-NUMB=0.,SPIN=0.,PARITY=+1.)

The isobaric analog state for the ground state of 46Ti.
References[1.] G.R. Satchler, Introduction to Nuclear Reactions, John Wiley & Sons, New York,
1980, pp. 239-242.
[2.] P. Marmier and E. Sheldon, Physics of Atomic Nuclei, Vol. I, Academic Press, New
York, 1969, p.227 ff.

I.6

November 2005

LEXFOR

Isomeric States(See also Cross Sections).
Definition: An isomeric state is defined as a long-lived energy state, where long-lived is,
generally, accepted as having a measurable half-life greater than ~0.1 sec.
A metastable state is an excited state having a half-life of the order of 0.1 seconds or longer.
The term ‘isomeric states’ refers to the ground and all known metastable states.
CodingWhere a nucleus has a known metastable state, the isomeric states are indicated by an isomercode following the isotope code,4 e.g., 95-AM-242-M1. (See EXFOR Manual Chapter 6:
Coding of nuclides and compounds)
Partial reactions leading to isomeric states are coded by entering the isomer code in
REACTION SF4. Sums and ratios are given algebraically.
Examples:(…(…,…)Z-S-A-M1,,SIG)(…(…,…)Z-S-A-M/G,,SIG/RAT)(…(…,…)Z-S-A-M1+M2,,SIG)

Isomer codes are used in SF4 only for partial reactions. They must not be used when the total
cross section (including isomeric decay) is measured, i.e., the extension G+M is never used.
When the variable nucleus formalism is used, i.e., nuclei are coded within a data table under
the data headings ELEMENT and MASS, the isomer is coded using the data heading ISOMER
and numerical isomer codes; see EXFOR Manual Chapter 6: Variable Nucleus. These arelinked to the decay information by the use of flags given using the field heading DECAYFLAG (see Flags).
The assignment of isomeric states for a given nucleus may vary in the literature according to
the growing knowledge of a particular nucleus. In order to define an isomeric state uniquely,
at least the half-life for the isomer must be coded (see Decay Data). Any other information
about its decay properties, if given by the author, should be included under the keyword
DECAY-DATA.
Uncertain Isomeric Contributions
Sometimes experimental data cannot be accurately assigned to specific isomeric states. If
the cross section for the isomeric state specified was measured, and partial feeding from ametastable state via isomeric transition may be included, either because the isomeric state
decays only partially by isomeric transition, or because its half-life is long in comparison
with the lower isomeric state measured, one of the branch codes following (REACTION SF5)should be used.
M+ Including formation via partial isomeric transition(M) Uncertain whether formation via partial isomeric transition is included

4

For a target nucleus, the ground state is coded without an isomer code.

November 2005

I.7

LEXFOR

Isomeric States (continued)
These codes are used only for partial feeding from a higher isomeric state. Where 100% of
the isomeric decay is included the sum reaction should be coded, e.g., G+M1.
Quasi-metastable states (states with a measurable half-life less than 0.1 seconds).
When activation data are measured for quasi-metastable states, that is, the half-life and decay
radiations are measured for the level, the excited state is specified using an isomer extensionof the type L, L1, etc., in the isomer code in REACTION subfield 4. The significance of theextension is simply to link the levels with the decay data, and would be significant only
within a given data set.
Examples:
BIB
REACTION

1 (39-Y-89(N,2N)39-Y-88-L1,,SIG)
2 (39-Y-89(N,2N)39-Y-88-L2,,SIG)
G (39-Y-89(N,2N)39-Y-88-G,,SIG)
SAMPLE
99.99% enriched Y2O3 sample.
DECAY-DATA1 (39-Y-88-L1,320.MICROSEC,DG,392.7)
2 (39-Y-88-L2,14.6MSEC,DG,232.2,,DG,442.8)
G (39-Y-88-G,107.D,DG,898.,,DG,1836.)
ENDBIB
BIB
REACTIONSAMPLE
DECAY-DATA(81-TL-203(N,2N)81-TL-202-L/G,,SIG/RAT)
99.99% enriched TlCl sample.
(81-TL-202-L,536.MICROSEC,DG,459.6,,DG,490.7)(81-TL-202-G,12.5D,DG,439.7,,DG,969.6)

ENDBIBSee also Independent and Cumulative Data.

I.8

November 2005

LEXFOR

Light-Nuclei Reactions (Z<6)
The light-nuclei reactions require special care, because many different notations exist. For
example, the notations Li(n,d), Li(n,nd), Li(QQ  PD\ DOO GHVFULEH WKH LGHQWLFDO UHDFWLRQ
Li(QQG 
Data retrievals for light-nuclei reactions are more difficult if the notations for these reactions
are not standardized. Therefore, they should be entered using the following general rule: theheaviest of the reaction products is defined as the residual nucleus, and the remaining
reaction products are sorted as given on EXFOR Manual Chapter 6: Reaction field.
In angular or energy distributions the particle considered must be given in reaction SF7 when
not self-evident. (See Particles).
Example: In the reaction 6Li(n,2np)4He, the angular distribution:of the neutrons:(3-LI-6(N,2N+P)2-HE-4,,DA,N)of the protons:(3-LI-6(N,2N+P)2-HE-4,,DA,P)of the alphas:(3-LI-6(N,2N+P)2-HE-4,,DA,A)
Neutron reactions
To aid the compiler, the following table lists all possible light-nuclei reactions induced byneutrons on stable nuclei, together with their thresholds and REACTION codes. Note that thetable gives only the end products and that, in some cases, competing reactions exist that leadto the same end products.
No REACTION codes other than those listed on the following pages should be used in
EXFOR for the light-nuclei neutron-induced reactions, except when the branch code SEQ isgiven (see under Particles). In addition to the processes listed, only scattering processes aswell as sum cross sections, such as absorption, nonelastic, charged-particles emission, etc.,
are defined for these nuclei.
Note: n-p scattering is always coded as 1-H-1(N,EL)1-H-1.

November 2005

L.1

LEXFOR

Light-Nuclei Neutron Reactions (Z<6) (continued)
ReactionH(Q '
D(Q 7D(n,2np)
T(n,2nd)T(n,3np)3
He(Q 4He
3
He(n,pt)3
He(n,2d)3
He(n,npd)
3
He(n,2n2p)4
He(n,dt)
4
He(n,npt)4
He(n,2n)3He
4
He(n,n2d)
6
Li(Q 7Li
6
Li(QW6
Li(QQG
6
Li(n,p)6He
6/L QQS
6
Li(n,nt)3He
7
Li(Q 8Li
7
Li(QQW 2
7
Li(n,2n)6Li
7
Li(n,d)6He
7/L QQG
7
Li(n,np)6He
7/L QQS 3
9
Be(Q 10Be
9
Be(Q 6He
9
%H QQ
9
Be(n,t)7Li
9
Be(n,p)9Li
9Be(n,d)8Li
9
Be(n,n d)7Li
9
Be(n,np)8Li
9
Be(n,nt)6Li
9
Be(n,3n)7Be
9
Be(n,n 3He)6He
10
B(Q 11B
10
B(n,p)10Be

Threshold (MeV)1
0
0
3.34
8.35
11.31
0
0
4.35
7.32
14.
21.97
24.76
25.72
29.80
0
0
1.71
3.19
5.43
18.42
0
2.81
8.29
8.87
11.06
11.41
14.76
0
0.67
1.85
11.59
14.74
16.28
18.54
18.76
19.66
22.85
23.54
0
0

REACTION
1-H-1(N,G)1-H-2
1-H-2(N,G)1-H-3
1-H-2(N,2N)1-H-1
1-H-3(N,2N)1-H-2
1-H-3(N,3N)1-H-1
2-HE-3(N,G)2-HE-4
2-HE-3(N,P)1-H-3
2-HE-3(N,D)1-H-2
2-HE-3(N,N+P)1-H-2
2-HE-3(N,2N+P)1-H-1
2-HE-4(N,D)1-H-3
2-HE-4(N,N+P)1-H-3
2-HE-4(N,2N)2-HE-3
2-HE-4(N,N+D)1-H-2
3-LI-6(N,G)3-LI-7
3-LI-6(N,T)2-HE-4
3-LI-6(N,N+D)2-HE-4
3-LI-6(N,P)2-HE-6
3-LI-6(N,2N+P)2-HE-4
3-LI-6(N,N+T)2-HE-3
3-LI-7(N,G)3-LI-8
3-LI-7(N,N+T)2-HE-4
3-LI-7(N,2N)3-LI-6
3-LI-7(N,D)2-HE-6
3-LI-7(N,2N+D)2-HE-4
3-LI-7(N,N+P)2-HE-6
3-LI-7(N,3N+P)2-HE-4
4-BE-9(N,G)4-BE-10
4-BE-9(N,A)2-HE-6
4-BE-9(N,2N+A)2-HE-4
4-BE-9(N,T)3-LI-7
4-BE-9(N,P)3-LI-9
4-BE-9(N,D)3-LI-8
4-BE-9(N,N+D)3-LI-7
4-BE-9(N,N+P)3-LI-8
4-BE-9(N,N+T)3-LI-6
4-BE-9(N,3N)4-BE-7
4-BE-9(N,N+HE3)2-HE-6
5-B-10(N,G)5-B-11
5-B-10(N,P)4-BE-10

1

R. J. Howerton, et al., Thresholds of Nuclear Reactions, Lawrence Livermore National Laboratory report
UCRL-14000, (1964).
2
Via 5He, 7*Li, 4H, or three-particle breakup (Nucl. Phys. A98 (1967) 305.
3
Including search for bound tri-neutron.

L.2

November 2005

LEXFOR

Light-Nuclei Neutron Reactions (Z<6) (continued)
Reaction
10% QW 5
10
B(Q 7Li6
10
B(n,d)9Be
10
B(QQ 6Li
10
% QQG10
B(n,np)9Be
10% QQS
10
B(n,3He)8Li
10
B(n,n3He)7Li
10
B(n,nt)7Be
10
B(n,3n)8B
11
B(Q 12B
11
B(Q 8Li
11
B(QQ 7Li
11
B(n,d)10Be
11
B(n,t)9Be
11
B(n,p)11Be
11
B(n,np)10Be
11% QQW11
B(n,2n)10B
11
B(n,nd)9Be
11% QQS
11
B(n,3He)9Li
11
B(n,n3He)8Li
12
C(Q 13C
12
C(Q 9Be
12& QQ
12
C(n,p)12B
12C(n,d)11B
12
C(n,np)11B
12
C(n,t)10B
12
C(n,2n)11C
12
C(n,3He)10Be
12
C(n,n3He)9Be
12
C(n,nd)10B
12& QQSW
12
C(n,3n)10C

Threshold (MeV)4
0
0
4.79
4.90
6.62
7.24
9.28
17.32
19.56
20.54
29.72
0.
7.23
9.44
9.82
10.42
11.70
12.25
12.25
12.50
17.25
21.70
25.73
29.68
0
6.17
7.98
13.63
14.87
17.29
20.50
20.28
21.09
28.47
27.28
29.65
34.47

REACTION
5-B-10(N,T+A)2-HE-4
5-B-10(N,A)3-LI-7
5-B-10(N,D)4-BE-9
5-B-10(N,N+A)3-LI-6
5-B-10(N,N+D+A)2-HE-4
5-B-10(N,N+P)4-BE-9
5-B-10(N,2N+P+A)2-HE-4
5-B-10(N,HE3)3-LI-8
5-B-10(N,N+HE3)3-LI-7
5-B-10(N,N+T)4-BE-7
5-B-10(N,3N)5-B-8
5-B-11(N,G)5-B-12
5-B-11(N,A)3-LI-8
5-B-11(N,N+A)3-LI-7
5-B-11(N,D)4-BE-10
5-B-11(N,T)4-BE-9
5-B-11(N,P)4-BE-11
5-B-11(N,N+P)4-BE-10
5-B-11(N,N+T+A)2-HE-4
5-B-11(N,2N)5-B-10
5-B-11(N,N+D)4-BE-9
5-B-11(N,3N+P+A)2-HE-4
5-B-11(N,HE3)3-LI-9
5-B-11(N,N+HE3)3-LI-8
6-C-12(N,G)6-C-13
6-C-12(N,A)4-BE-9
6-C-12(N,N+2A)2-HE-4
6-C-12(N,P)5-B-12
6-C-12(N,D)5-B-11
6-C-12(N,N+P)5-B-11
6-C-12(N,T)5-B-10
6-C-12(N,2N)6-C-11
6-C-12(N,HE3)4-BE-10
6-C-12(N,N+HE3)4-BE-9
6-C-12(N,N+D)5-B-10
6-C-12(N,N+P+T+A)2-HE-4
6-C-12(N,3N)6-C-10

4

R. J. Howerton, et al., Thresholds of Nuclear Reactions, Lawrence Livermore National Laboratory report
UCRL-14000, (1964).
5
Via 8Be, 7Li(2nd excited state), or three-particle breakup.
6
To ground state and 1st excited state; 2nd excited state decays to W 

November 2005

L.3

LEXFOR(blank page)

L.4

November 2005

LEXFOR

Measurement Techniques
Physics information on experimental measurement techniques is entered under several
information-identifier keywords (see EXFOR Manual Chapter 7 for coding rules).
FACILITY:1 used to identify the main apparatus or machine used in the experiment, e.g.,reactor or cyclotron.
The institute at which the facility resides may be entered, if known, following the facility
code. This is especially important if there is more than one institute associated with theexperiment.
Example: (LINAC,1USAORL)Information on the facility used should always be given, if known, except when not relevant,e.g., with respect to spontaneous fission.
INC-SOURCE: used to enter the source of the incident-projectile beam used in theexperiment (see Incident Beam Source).
SAMPLE: used to identify information on sample material characteristics (see also Sample).
DETECTOR1: used to enter information on detectors used in the measurement. Detectors
used as monitors are also entered under this keyword.
For coincidence measurements, the code COINC may be entered followed by the detectors
used in coincidence.
Example: (COINC,NAICR,SILI)For telescopes or spectrometers, the code TELES or the code for the spectrometer may beentered followed by the component detectors.
Examples: (TELES,PROPC,SCIN)(MAGSP,MWDC,SCIN)
For particles detected and the keyword PART-DET see Particles; for their energies and the
keyword EN-SEC, see Secondary Particles: Secondary Energy.
METHOD1: describes the experimental technique(s) employed in the experiment, e.g.,
activation.
Information that can be entered under one of the more specific keywords, above, should not
be entered under METHOD.

1

One of the following keywords must be present: FACILITY, DETECTOR, ANALYSIS, or METHOD.

November 2005

M.1

LEXFOR

Miscellaneous Data
(For reaction modifier MSC, see General Quantity Modifiers).
Supplementary information for which no data heading has been defined may be entered in adata field using the data heading MISC (or MISC1, MISC2, etc., if more than one is given).
Such data are usually entered in the DATA section, but may also be entered in the
COMMON section, although the latter is not recommended.
The meaning of these data headings is explained in the BIB section under the keyword
MISC-COL. In order to link explanations when more than one miscellaneous data field isgiven, the data heading is given as a code under MISC-COL, followed by the free text
explanation. This formalism is the same as for error fields. See coding example, below.
If uncertainties are given, they are entered in the COMMON or DATA section using theheadings MISC1-ERR, MISC2-ERR, etc. The data heading is not coded under MISC-COL,
but the source of the uncertainties should be given, if known.
If the information under the data heading MISC is given in units for which no data unit exists,
the data unit SEE TEXT is entered and the explanation is given in free text under the
keyword MISC-COL. (This is to avoid introducing data units that are unlikely to occur
often.) The data unit SEE TEXT must not be used for an independent variable or adependent variable.
Example:BIB…
MISC-COL

ENDBIBNOCOMMON
DATA
EN
MEV
…
…
ENDDATA(MISC1) Comment describing contents of 1st miscellaneous field and its
uncertainty, and the units in which it is given.
(MISC2) Comment describing contents of 2nd miscellaneous field

DATA
B
…
…

MISC1
SEE TEXT…
…

MISC1-ERR
SEE TEXTMISC2NO-DIM

It follows that MISC may not be used for:• any data defined under REACTION,• information for which a data heading keyword has been defined,• independent variables.

M.2

November 2005

LEXFOR

Multilevel Resonance Parameters(See also Single-Level Resonance Parameters, Quantum Numbers).
In analyzing resonance structure for fissile nuclides, it is necessary to use a multilevel
formalism to account for interference effects from neighboring resonances and also those due
to distant resonances.
The multilevel formalism generally used is Reich-Moore. Vogt, and Adler-Adler have also
been used in the past. All three are derived from the R-matrix theory of Wigner andEisenbud.
Resonance Energy (E0) is coded in EXFOR in one of two ways:
1. When the resonance energy is determined by the author, it is assigned a REACTION codeand entered into the data table under the corresponding DATA field (see codes underparameter type).
2. When the resonance energy is not determined by the author, but is taken from othersources, it should be entered into the data table as an independent variable under the data
heading (see codes under parameter type). In this case, it should only be entered for thoseresonances for which the author has presented other resonance parameters.
Negative energy resonances, in many cases, will influence very low energy cross sections.
These bound levels should be coded with the negative energy, as given.
Reich-Moore and Vogt2 Resonance Parameters
In the Vogt and Reich-Moore formalisms, cross sections are expressed in terms of R-matrix
level parameters. Cross sections due to resonance levels of the same spin and parity are
related to the elements Unc of the collision matrix as follows:
Total cross section: σ nT = 2πλ2n g Re(1 − U nn )Other cross sections: σ nR = πλ2n g δ nR − U nR
where:

n = neutron wave length in the center-of-mass systemg = statistical weight factor
nc = Kronecker delta

and Re stands for the real part of the expression in parentheses.
The collision matrix U is related to the nuclear level properties by means of the derivative
matrix R, in the following form:γ ×γ λR=∑ λ
λ Eγ − E
where:

2γ λ × γ λ LVWKHGLUHFWSURGXFWRIWKHYHFWRUV  UHIHUVWROHYHOVThe diagonaOHOHPHQWVRI are reduced width parameters.

Seldom used.

November 2005

M.3

LEXFOR

Multilevel Resonance Parameters (continued)
The collision matrix U can be related to the derivative matrix R through the matrix:(1 − RL ) R
0 −1

where:

L0 = L-B ; B is a constant diagonal matrix; L is a complex matrix withelements being a function of momentum l.

Both the Vogt and the Reich-Moore formulas require that off-diagonal matrix elements
describing interference in the radiative capture channels must vanish.
The Reich-Moore formula (see Reich [2]) involves summation over levels and a matrix
inversion with respect to channels.
The matrix (1 - RL) is partitioned into a 2×2 matrix, each element of which leads to adefinition on the matrixiΓ1/λc2Γ1/λc2′∑
2 λ E −E− i Γλλγ2The neutron fission cross section can be expressed by:
Kcc′ =

l +1

σ nf = ∑ 4πλ2n g (1 − K nC )−12

c=2

where l = number of fission channels
Similar expressions are obtained for other partial cross sections.
Reich-Moore Resonance Parameters are entered under the quantity codes:(N,0),,EN(N,TOT),,WID,,RM(N,G),,WID,,RM(N,F),1,WID,,RM(N,F),2,WID,,RM(N,F),,WID,,RM(N,EL),,WID,,RM(N,EL),,WID/RED,,RM

E

I
I
I
Q
l
Q

Resonance energy3; units of energy (e.g., eV)
Total width; units of energy
Capture width; units of energy (including all
primary gamma decays not followed by neutron or
charged-particle emission).
4
Fission width for channel 1; units of energy
2
Fission width for channel 2; units of energy
Total fission width; units of energy
Neutron width; units of energy
Reduced neutron width, l = orbital angularmomentum; units of energy

3

The resonance energy, if not assigned by the author, is entered in the data table using the heading EN-RES.
7KHUHODWLYHSKDVHVRI IDQG I are 0 or 180 degrees; therefore, the parameter values are given with either apositive or negative sign.

4

M.4

November 2005

LEXFOR

Multilevel Resonance Parameters (continued)
The Vogt Formula (see Vogt [3]) involves summation of channels and matrix inversion withrespect to levels, and requires that level interference in the neutron channel be equal to zero.
The inversion of the channel matrix (1-RL0) leads to the definition of the level matrix A,
which s given by:

(A )
−1

λλ

= ( Eλ − E ) δ λλ ′ −′1∑ Γ1/λc2Γ1/λ ′c22 cwhere: c is the channel number.
A reduced neutron width for an s-wave resonance is defined as: Γλ0n = 2 gΓλn E 1 / 2
Vogt Resonance Parameters are entered under the quantity codes:(N,0),,EN(N,TOT),,WID,,VGT(N,G),,WID,,VGT

E(N,F),1,WID,,VGT(N,F),2,WID,,VGT(N,EL),,WID,,VGT(N,EL),,WID/RED,,VGT

I

(N,0),,PHS,,VGT

L M

I
Q
l
Q

Resonance energy5; units of energy (e.g., eV)
Total width; units of energy
Capture width; units of energy (including all
primary gamma decays not followed by neutron or
charged-particle emission)
Fission width for channel 1; units of energy
Fission width for channel 2; units of energy
Neutron width; units of energy
Reduced neutron width, where l = orbital angularmomentum; units of energy × square-root of energy
Relative phase of channel iDQG j; units of angle

Adler-Adler6 Resonance Parameters
The Adler-Adler formalism (see Adler [4]) is a generalized Kapur-Peierls formalism in whichcross sections are given in terms of .DSXU3HLHUOVSROHVDQG DQGUHVLGXHV*DQG+
The resonance part of the reaction cross section (without Doppler Broadening) in the AdlerAdler formalism is given by:
Grkν k + H rk ( µk − E )1
σ λ (E) =∑2
E k( µk − E ) + vk2
where:

5
6

G, H, µ and  DUH WUHDWHG DV FRQVWDQWV VLQFH WKH\ KDYH RQO\ D ZHDN
energy dependence.

The resonance energy, if not assigned by the author, is entered in the data table using the heading EN-RES
Seldom used.

November 2005

M.5

LEXFOR

Multilevel Resonance Parameters (continued)
Adler-Adler coefficients are entered under the quantity codes:µk(…,0),,EN,,AA(…,TOT),,WID,,AAk(…,F),,AG,,AA(…,F),,AH,,AA(…,G),,AG,,AA(…,G),,AH,,AA(…,TOT),,AG,,AA(…,TOT),,AH,,AA

GI
HI
G
H
G
H

Resonance energy7; units of energy (e.g., EV)
Corresponding to half the total width; units ofenergyFission symmetry coefficient; in B*EV*RT-EV
Fission asymmetry coefficient; in B*EV*RT-EV
Capture symmetry coefficient; in B*EV*RT-EV
Capture asymmetry coefficient; in B*EV*RT-EV
Total symmetry coefficient; in B*EV*RT-EV
Total asymmetry coefficient; in B*EV*RT-EV

The parameters are functions of µ, which corresponds to the resonance energy. Since thisrepresentation of the energy causes difficulty in a data retrieval by energy, the energy limitsof the Adler-Adler fit must be entered explicitly in the COMMON section under the dataheading keywords EN-MIN and EN-MAX.
R-Matrix Resonance Parameters
The R-Matrix reduced width γ2 is given by:∋=2γ2P
where: P = penetrability
Reaction coding: (…,WID/RED,,RMT)
Units: code from Dictionary 25 with the dimension E (e.g., EV)
The square root of this quantity, γ, is referred to as the reduced width amplitude.
Reaction coding: (…,WID/RED,,RMT/AMP)
Units: code from Dictionary 25 with the dimension RE (e.g., RT-EV)

References[1.] M. S. Moore, Idaho Nuclear Engineering Laboratory report IN-1222 (1969) p. 199.
[2.] C. W. Reich, and M. Moore, Phys. Rev. 111, 929 (1958).
[3.] E. Vogt, Phys. Rev. 112, 203 (1958).
[4.] D. B. Adler, and F. T. Adler, Argonne National Laboratory report ANL-6792 (1963) p.
695.

7

The resonance energy, if not assigned by the author, is entered in the data table under the heading MUADLER.

M.6

November 2005

LEXFOR

Multiple Reaction Formalism
At present, the following classes of data may be coded using Multiple Reaction Formalism
8(compare EXFOR Manual Chapter 6). In all cases, SF1 and SF2 of the REACTION string
must be the same. See Example on following page.
1. Resonance parameters of the same isotope and target, determined in the same analysis;
Example: REACTION

1(…(N,0),,EN)2(…(N,EL),,WID)

2. Multiple representations of the same data: when one of the reactions given has been
deduced from the other; the appropriate status code is entered with the relevant pointer. Some
examples are:• absolute cross sections deduced from ratio measurements using standard reference data.
• S-factors deduced from cross sections.
Example:REACTIONSTATUS1((94-PU-239(N,F),,SIG)/((92-U-235(N,F),,SIG))
2(94-PU-239(N,F),,SIG)
2(DEP,12345006) free text.

Explanation in free text may be given following the status code and/or following the reactioncode.
3. Partial cross sections of a sum reaction (i.e., for the REACTION keyword, all subfields
except SF5 (Branch) are equal).
a.) Isomer data (branches, ratios, etc.) of the same reactions.
b.) Data from different reaction mechanisms not measured directly but deduced by author(see Reaction Mechanisms for defined mechanisms).
d.) Binary and ternary parts for fission measured.
e.) Light and heavy fragment parts for a given fission yield.
Example:REACTION

M(39-Y-89(N,INL)39-Y-89-M,,SIG)
G(39-Y-89(N,INL)39-Y-89-G,,SIG)

4. Data measured simultaneously for the production of specific particles or nuclides where
the author has assigned values to given reactions based on systematics or theoreticalconsiderations.
Examples:a.) REACTION

b.) REACTION

81(…(P,2N)…)
2(…(P,3N)…)
3(…(P,4N)…)
1(…(N,A)…)
2(…(N,NA)…)

Please submit a LEXFOR entry for any additional types of data before transmitting these data.

November 2005

M.7

LEXFOR

Multiple Reaction Formalism (continued)
5. Data for the same reaction obtained by different types of analysis on the same
experimental data; in this case the code must be repeated for each analysis.
Example:REACTION
DETECTOR

1 (79-AU-197(N,G)79-AU-198,,SIG)
2 (79-AU-197(N,G)79-AU-198,,SIG)
1 (NAICR)
2 (GELI)

Example:BIB
REACTION…
ENDBIBNOCOMMONDATAEN…
ENDDATAG (39-Y-89(N,INL)39-Y-89-G,,SIG)
M (39-Y-89(N,INL)39-Y-89-M,,SIG)DATA…

G DATA…

M

6. Components of polarization for a given reaction measured in a given experiment.
Examples:a) REACTION

1(…(P,A)…,,POL/DA,,VAP)
2(…(P,A)…,20,POL/DA,,TAP)
3(…(P,A)…,21,POL/DA,,TAP)
4(…(P,A)…,22,POL/DA,,TAP)b) REACTION

1(…(N,P)…,,POL/DA)
2(…(N,P)…,,POL/DA,,ANA)

Where only the product nucleus is variable for a given reaction, (i.e., for the REACTION
keyword, SF1, SF2 are constant and subfield 3 is either X or F) the Variable Nucleus
Formalism may be used (see EXFOR Manual Chapter 6).

M.8

November 2005

LEXFOR

Multiplicity
Definition: Particle yield per event.
REACTION Coding: MLT in SF6.
Examples:(…(P,A)…,,MLT,G)(…(N,X)0-G-0,,MLT)\LHOGIURP S UHDFWLRQ\LHOGIURPDOOQHXWURQLQGXFHGUHDFWLRQV

Partial Multiplicity
In many cases the experimental arrangement will be such that not all of the particles
produced will be detected. In such cases the branch code PAR must be used in REACTION
SF5, and the energy range of the selected particles must be entered in the COMMON or
DATA section. A common experimental occurrence of this will be limits on the energies ofthe particle detected.
Authors often deduce the multiplicities as a function of spin or momentum transfer; thesededuced results should not be compiled as experimental data.
Neutron Multiplicity
The neutron multiplicity should be coded as given above only for those reactions for which
special codes do not exist. For neutron multiplicity from fission, see Neutron Yield.

November 2005

M.9

LEXFOR

Multipolarity
Definition  $QJXODU PRPHQWXP RI TXDQWD DEVRUEHG E\ WKH QXFOHXV  7KHVH DUH JLYHQ DV
electrical or magnetic monopoles, dipoles, quadrupoles, or octupoles.
REACTION coding: Branch code in SF5: EP (for electric polarity) or MP (for magnetic
polarity).
The polarity is coded in the data table under the data heading POLAR:
0. = monopole, 1. = dipole, 2. = quadrupole, 3. = octupole.
Examples:a.) Electric dipole component of photo-neutron cross section
REACTION…
COMMONPOLAR
NO-DIM
1.
ENDCOMMON(…(G,N)…,EP,SIG,,,EXP)b.) Magnetic quadrupole component of photo-absorption cross section
REACTION…
COMMONPOLAR
NO-DIM
2.
ENDCOMMON

M.10(…(G,ABS),MP,SIG,,,EXP)

November 2005

LEXFOR

Neutron Yield
The following special terms are defined for neutron yields from fission. For other neutron
yields, see Multiplicity.

()

Nu-bar ν

Definition: Average number of fission neutrons emitted per fission event.
REACTION Coding:(…(N,F),,NU)(…(0,F),PR,NU)(…(P,F),DL,NU)(…(N,F)NPART,NUM,NU)(…(N,F)MASS,,NU,FF)

total neutron-induced fission nu-bar ( ν )spontaneous fission prompt nu-bar (ν p )proton-induced fission delayed nu-bar (ν d )probability for the emission of n neutrons from neutroninduced fission (n is coded in the data section under theheading PART-OUT).
number of neutrons emitted from a fragment of given
mass.

Sum rule: ν = ν p + ν d
See also Delayed Fission Neutrons

Eta
Definition: The average neutron yield per nonelastic event for neutron-induced reactions.
For the thermally fissile isotopes, where fission and capture are, up to a certain threshold, the
RQO\QRQHODVWLFSURFHVVHV LVGHILQHGDVDYHUDJHQHXWURQ\LHOGSHUDEVRUSWLRQREACTION Coding:(N,NON),,ETA) LQJHQHUDO(N,ABS),,ETA) IRUWKHUPDOO\ILVVLOHQXFOHL(N,ABS),,ETA,,RES) DWUHVRQDQFHIRUWKHUPDOO\ILVVLRQLQJQXFOHL,QWKHFDVHRIWKHUPDOQHXWURQILVVLRQ LVUHODWHGWRν by:

η =ν

σf
σ abs

For further related quantity codes see Dictionary 36.

November 2005

N.1

LEXFOR

Nonelastic
Definition: The sum of all energetically possible interactions with Q≠0; effectively, the sumof all interactions except elastic scattering.
The nonelastic cross section is a sum cross section and should only be used when two or
more of the relevant interactions are possible.
REACTION Coding: Process code NON in SF3.
Example: (…(N,NON),,SIG)
Sum rules: Nonelastic= Total minus Elastic= Absorption plus Inelastic.

For average neutron yield per nonelastic process, see Neutron Yield: Eta.

N.2

November 2005

LEXFOR

Nuclear Quantities
A quantity that does not refer to a nuclear reaction, but is a property of a given nuclide, iscoded by entering the nucleus to which the data are pertinent as the target nucleus (SF1)under REACTION; a zero is entered in SF2 (incident projectile field).
At present, the following nuclear quantities are coded in EXFOR.
1. Spontaneous fission, see Fission.
2. Level-Density Parameter: proportional to single-particle level spacing at at top of Fermisea in the Fermi-gas model of the nucleus, in specified formalism.
REACTION Coding: LDP in SF6 (Parameter).
Example: (…(0,0),,LDP)For nuclei around A = 208, neutron emission spectra can only be interpreted by assuming avariable level-density parameter, i.e., increasing density with increasing excitation energy.
Therefore, the incident projectile must be specified in REACTION SF2 and its energy must be
coded.
Example: (…(N,INL)…,,LDP) where, Z-S-A is the target nucleus
The incident-neutron energy is coded, as usual, under the data heading EN.
3. Nuclear Temperature - from Fermi-gas model of the nucleus.
REACTION Coding: TEM in SF6 (Parameter).
Example: (…(0,0),,TEM)
4. Spin-cut-off factor
REACTION Coding: SCO in SF6 (Parameter).
Example: (…(0,0),,SCO)
Subentries with nuclear quantities should, if applicable, contain the STATUS code DEP withcross-reference to the subentry containing the reaction data from which the nuclear quantity
was derived.
Example: STATUS

November 2005

(DEP,30343003)

N.3

LEXFOR(blank page)

N.4

November 2005

LEXFOR

Partial Reactions
Definition: A partial reaction, as defined for EXFOR, is a reaction leading to or proceeding
through a given excited state, and excludes isomeric states (see Isomeric States). An
excitation function is the energy dependence of a partial reaction cross section leading to theexcitation of a discrete level or to the production of a particular radiation or particle group.
REACTION Coding: PAR in SF5 (Branch)
Example: (…(N,INL)…,PAR,SIG)
The energy must be given in the COMMON or DATA section under a secondary-energy data
heading (Family E), e.g., E-EXC.
Partial reactions leaving the residual nucleus (reaction product) in an excited state. The
excited state is defined by specifying one, several or a range of:• level energies (default is level energy of reaction product)• excitation energies (default is excitation energy of reaction product)• reaction Q-values (default is Q-value for excitation in reaction product)• secondary particle energy (of particle considered)• energy gain (primary to particle considered)• energy degradation (primary to particle considered)
The particle considered in an experiment is:• either the particle given in REACTION SF3 (Process),• or, for other particles,, given in SF7 (Particle Considered).
When the data is a function of the secondary energy of more than one secondary particle, thesecondary energies for the particles must be defined under the information-identifier keyword
EN-SEC (see EXFOR Manual Chapter 7: EN-SEC and Secondary Particles).
Example:REACTION
EN-SEC(…,N+P)…,,DA2/DE2,P/A)(E1,P)(E2,A)

For partial reactions specified by the sequence of outgoing particles, see Particles.
If ratios of partial reactions for different secondary energies are given, they should be codedusing the reaction separator "//", see Ratios. The secondary energies are given under the data
headings with the extensions-NM and -DN.
Example: E-EXC-NM

E-EXC-DN

For other partial reactions due to competing reaction mechanisms, see Reaction
Mechanisms.

November 2005

P.1

LEXFOR

Partial Reactions (continued)
Gammas in the Continuum Region
When data are measured for a range of gamma energies that includes the continuum region,
data may be deduced for a range of discrete gammas as separated from the range ofcontinuum gammas.
REACTION coding: DIS (discrete) or CON (continuum) in SF5 (Branch).
Note: The code DIS should not be used below the continuum region.
Example:REACTION

1(26-FE-56(N,X)0-G-0,DIS,SIG)
2(26-FE-56(N,X)0-G-0,CON,SIG)

Reactions that lead by the same particle sequence to the same reaction products, but
through different reaction-decay mechanisms.
Example:a.) 12C(n,n’)12*C → 8*Be →
b.) 12C(n,n’)12*C →The intermediate states should be specified in the data table and explained under the
information-identifier keyword EN-SEC as clearly as possible.
Example:REACTION
EN-SEC

P.2

1(6-C-12(N,N+2A)2-HE-4,PAR,SIG)
2(6-C-12(N,N+2A)2-HE-4,PAR,SIG)
1(E-LVL,4-BE-8)2(E-LVL,6-C-12)

November 2005

LEXFOR

Particles(See also Secondary Particles).
Particles participating in a reaction
In general, the incident projectile is coded in reaction SF2. Particles resulting from the
REACTION to be defined are given in SF3 and SF4.
If the incident energy is given in center-of-mass, the projectile (A) is heavier than the target(B), and reversing the order of the target and the projectile does not change the numerical
data, the reaction is coded using the "tautology" formalism:
Example:REACTION((9-F-19(1-H-2,P)………)=(1-H-2(9-F-19,P)…………))Sometimes, data are given for partial reactions where the sequence of outgoing processes/
particles is defined, for example:
total (n,np) = partial (n,np) + partial (n,pn)
(1)
(2)
(3)
The corresponding REACTION codes are:(1) (…(N,N+P)…,,SIG)(2) (…(N,N+P)…,SEQ,SIG)(3) (…(N,P+N)…,SEQ,SIG)
Note that the code SEQ should be given within the reaction code only when it is a partial
reaction. If the author states that the reaction proceeds, e.g., totally in the sequence (n,pn)
without any contribution in the sequence (n,np), then the reaction is coded primarily as (1),above. A comment stating that the reaction proceeds entirely in the sequence (n,pn) may be
added in free text (if this occurs at all) or, alternatively, both codes may be given in the formof a tautology:
Example:REACTION((…N,N+P)…,,SIG)=( …(N,P+N)…,SEQ,SIG))

For the following partial reactions the specified sequence of process and particle codes isalways indicated by the code SEQ.
1. Excitation of excited level(s) that decay by fission:(n,n'f) cross section: (N,N+F),SEQ,SIG(n I FURVVVHFWLRQ (N,G+F),SEQ,SIG
2. Emission of a primary gamma ray followed by unidentified decays:(n, x) cross section: (N,G+X),SEQ,SIG
This formalism can occur only for the process codes F and X.
For general rules on the coding of sequence of process/particle codes in REACTION SF3 andSF4 see EXFOR Manual Chapter 6.
For correlation data on secondary particles, see Correlations.

November 2005

P.3

LEXFOR

Particles (continued)
Particle Considered
Definition: The particle considered is the particle to which a given function refers, e.g., anangular or energy distribution, or a reaction to a specific particle group. In a reaction where
only one outgoing particle is specified in SF3, the particle considered is assumed to be thatparticle, unless there is an entry in SF7 (Particle Considered).
When the quantity given refers to a specific secondary particle (e.g., angular distributions),
the particle considered must be entered in reaction SF7 if:• more than one particle is given in reaction SF3,
• the particle considered is not given in reaction SF3,
• the quantity is a function of more than one secondary particle.
See EXFOR Manual Chapter 6 for coding rules.
Examples:a) (…(P,P+A)…,PAR,SIG,A)
partial cross section for a specific group.
b) (…(N,P)2-HE-4,,DA,A) angularGLVWULEXWLRQRI SDUWLFOHVc) (…(P,N+P)…,,DA/DA,P/A)
double differential cross section, d2σ/dΩn/dΩp .
If the code given in REACTION SF3 is a process code, and the reaction refers to a specificparticle, the particle considered is determined as follows:
INL: The particle considered is assumed to be the same as the incident projectile. If γ-rays are

considered, the code G must be entered in REACTION SF7.
angular distribution of(…(N,INL)…,,DA,G)
scattering.
F:

The particle considered is ambiguous and should be entered in REACTION SF7.
(…(N,F),,DA,FF)

X:

UD\V IURP LQHODVWLF QHXWURQ

angular distribution of fission fragments.

The particle considered is assumed to be the particle (or nuclide) for which the
production is measured (SF4). See Production Cross Sections.

Particles/Radiations Detected
Particles actually detected in the experiment may be identified using the keyword PART-DET(see EXFOR Manual Chapter: 7 PART-DET for coding rules). This keyword should be used
only in those cases where the particle detected is not obvious from the quantity given (seepreceding).
If the particle detected may be attributed to the decay of a specific nucleus, it may be codedusing the keyword RAD-DET (see EXFOR Chapter 7: RAD-DET for coding rules).
However, the keyword RAD-DET should not be used to duplicate information also coded
under the keyword DECAY-DATA.
The particles detected in a monitor reaction should not be included under the keywords
PART-DET or RAD-DET.
See Dictionary 33 for a list of permissible codes.
P.4

November 2005

LEXFOR

Particles (continued)
Distinguish the different codes:
DG - decay UD\VG- other UD\V
B- - decay electrons ( -)B+ - decay positrons ( +)ICE - internal conversion electronsE- other electrons
Particle pairs
If the angle given is the angle between a secondary particle pair or a secondary energy is
given as the c.m. energy of the relative motion of a particle pair emitted in the reaction, theparticles are specified in SF7.
Example: REACTION (…(…,…)…,,DA,N+P) angular distribution of n-p pair.
(…(…,…)…,,DE,P+A) energy spectrum on p-α pair.
Variable number of emitted particles.
If the data table contains yields or production cross sections as a function of the number of
secondary particles, and the number of particles is entered as a variable in the data table, SF4of the reaction keyword contains the code NPART and SF5 contains the code NUM:
See also Exfor Manual Chapter 6.
Example:BIB
REACTION…
ENDBIBNOCOMMON
DATA
EN
MEV
…
…
…
ENDDATA(…(…,X)NPART,NUM,…)

PART-OUT
NO-DIM
2.
3.
…

DATA
B
…
…
…

Undefined Reaction Channels.
In some cases a given residual nucleus may be produced by more than one reaction channel,e.g., (p,α) and (p,2n2p), but only the residual nucleus has been investigated. If it is clear that
more than one channel contributes (e.g., for energies well above the threshold for (p,2n2p)),
the process code X is entered in SF3 of the REACTION string. See Production Cross
Sections.

November 2005

P.5

LEXFOR

Particles (continued)
Where it is not clear whether the reaction channel is undefined or defined, the reaction iscoded as specified by the author with the code (DEF) in SF5.
Examples:P.6(…(P,A)…,(DEF),SIG)(…(P,2N+2P)…,(DEF),SIG)

November 2005

LEXFOR

Pointers
A pointer is a numeric or alphabetic character used to link pieces of EXFOR information.
(See EXFOR Manual Chapter 5 for details.)
Where feasible, the compiler may choose as pointers meaningful digits or characters. For
example, when the pointers refer to an isomeric ratio and the partial isomeric cross sections
leading to ground state and metastable states, the characters R, G and M, respectively, may bechosen as pointers. Or, when the pointers refer to the Legendre coefficient numbers 0, 2, and4, the digits 0, 2 and 4 may be chosen.
Caution to Compilers: Since a pointer links the information given only to other information
with the same pointer, or to information with no pointer, only one set of pointers may be used
for each data set.
The following is an example of an illegal use of pointers.
BIB
REACTION

M(79-AU-197(N,G)79-AU-198-M,,SIG)
G(79-AU-197(N,G)79-AU-198-G,,SIG)
MONITOR1(29-CU-63(N,2N)29-CU-62,,SIG)
2(29-CU-65(N,2N)29-CU-64,,SIG)
MONIT-REF 1(LISKIEN+,J,JNE,19,73,1965)
2(POLLEHN,J,ZN/A,16,227,1965)
ENDBIB(The monitor data is not linked to either reaction because the pointers are different.)
Pointers should be used carefully and only for those cases specified in the EXFOR Manual
Chapter 5.

November 2005

P.7

LEXFOR

Polarization1
If the spins of a collection of particles, either stationary or in a beam are oriented in all
directions with equal probability, the assembly is said to be unpolarized. If the spins are
predominantly oriented in one direction, the assembly is said to be polarized.
Under the influence of a spin-orbit force upon scattering from a target, an unpolarized beamof particles becomes polarized.
P( )The inverse of this situation is the asymmetric scattering of a polarized beam of particles.
The degree of polarization of such a beam may be determined by measuring the left-rightasymmetry upon scattering from a target nucleus that plays the role of an analyzer.
Pb

L

R

For elastic scattering from a spin-0 nucleus: the principle of Polarization-Asymmetry Equality
states that, for time-reversal invariant reactions, the polarization induced in a previously
completely unpolarized beam is identically equal to the asymmetry ensuing from thescattering of a perfectly polarized beam under the same conditions.

Conventions for quantities given in Cartesian coordinates
Basel Convention for spin-½ particles2
In nuclear reactions, the positive polarization of particles with spin-½ is taken in the directionv vvvof the vector product k in × k out where k in and k out are the circular wave vectors of theincoming and outgoing particles.

1
2

See [1970Ma].
See [1960Hu].

P.8

November 2005

LEXFOR

Polarization (continued)
Madison Convention for spin-1 particles; quantities given in Cartesian coordinates3
1. Polarization (P), the state of spin orientation of an assembly of particles, is referred to aright-handed coordinate system in which the positive z-axis is along the direction ofv v
momentum of the incident particles, and the positive y-axis along k in × k out (perpendicular tothe beam direction in the reaction plane) for the nuclear reaction which the polarized particles
initiate, or from which they emerge.
2. Analyzing power (A) is referred to a right-handed coordinate system in which the positivev v
z-axis is along the direction of the incident beam, and the positive y-axis along k in × k out for
the reaction.
The cross section for a reaction initiated by polarized particles with spin-1 may be written interms of Cartesian tensors as:σ = σ 0 1 + 32 p y Ay + 12 p zz Azz + 23 p xz Axz + 16 ( pxx − p yy )( Axx − Ayy ) 
3. In the expression for a nuclear reaction A(b,c)D, an arrow placed over the symbol denotesa particle in a polarized state.
r r
Example: A(b, c) D
Additional conventions
1. The following subscripts are defined:b refers to the beam polarizationrefers to the target polarizationt↑ spin up↓ spin down
ith component for beamik kth component for scattered particlethj component for targetjp pth component for recoil nucleus
N=n=y normal to the scattering plane
L=l=z
longitudinal, i.e., parallel to incident particle momentum in scattering plane
S=s=x
N✕ L (sideways), i.e., perpendicular to particle momentum in scattering plane
S

Laboratory system

L

L
b

s

c
l

S

L

b

A

A
l

D

D
S

s
l

c

S

Center-of-mass system

L

l

s

s

uuv
v
N and n are identical with direction out of page for all particles.

3

See [1971Sa].

November 2005

P.9

LEXFOR

Polarization (continued)
Occasionally, a 4-index notation is used; the order of the subscript in a 4-index notation is(i,j;k,p). A zero in a field denotes unpolarized or polarization not measured.
2. Y is the normalized yield.
3. σ0 is the differential cross section for an unpolarized (spin-averaged) beam.
I. Quantities given in Cartesian coordinates and compiled in EXFOR
Polarization: refers to the degree of polarization of an ensemble of particles.
Ps(θ) is the polarization of the outgoing particle beam as a function of angle.
where

σ P = σ 0 P(θ )REACTION Coding: ,POL/DA
Asymmetry: Asymmetry is the relative difference between:a. the number of particles scattered to the right and to the left in the reaction plane.

ε = ( L − R ) ( L + R ) = Pb Ay
where


Pb =
Ay =
L,R =

asymmetry
incident beam polarization
analyzing power of target
intensity of particles scattered left and right in the same plane under
the same angle.

REACTION coding: POL/DA,,ASY
b. the angular distribution for incident projectiles with their polarization vectors
perpendicular and parallel to the reaction plane.

ε = ( dσ ⊥ − dσ || ) ( dσ || + dσ ⊥ )REACTION coding: ,POL/DA,,ASY/PP
If data are given as (dσ || − dσ ⊥ ) /(dσ || + dσ ⊥ ) , the negative of the value given is coded.
c. the angular distribution for forward and backward scattered particles.

ε = ( dσ F − d σ B ) ( d σ F + d σ B )REACTION Coding: ,POL/DA,,ASY/FB
The angles are given as ANG1 and ANG2.

P.10

November 2005

LEXFOR

Polarization (continued)
Analyzing Power: the relative difference in the cross sections for corresponding spin up vs.
spin down.
Vector analyzing power (Ai or Ai,0;0,0 and Aj or A0,j;0,0):
REACTION Coding: Modifier ANA in SF8.
Examples:,POL/DA,,ANA

Analyzing power, An, incident projectile spin normal toscattering plane.
LON,POL/DA,,ANA Analyzing power, Al, incident projectile spin parallel to incident
particle momentum in scattering plane (longitudinal).

Tensor analyzing power (Aij or Aij,0,0,0): initial spin state correlation parameters.

A yy = ANN = ε
REACTION Coding:

Pb Pt

Modifier ANA in SF8, and a branch code in SF5 giving
components of beam and target spin

Example:NN,POL/DA,,ANA

Tensor analyzing power, ANN, incident projectile and target
spins normal to scattering plane.

Spin-Correlation Parameter (Ckp or C0,0,k,p): final spin state correlation parameters.
For spins in the scattering plane:Ckp =d σ / d Ω↑↑ + d σ / d Ω ↓↓ − d σ / d Ω↑↓ − dσ / d Ω ↓↑1 Y↑↑ + Y↓↓ − Y↑↓ − Y↓↑=d σ / d Ω ↑↑ + d σ / d Ω↓↓ + dσ / d Ω ↑↓ + d σ / d Ω ↓↑ Pb Pt Y↑↑ + Y↓↓ + Y↑↓ + Y↓↑
LU

Pk
A
LD
RU

Pp

A

RD

For spins normal to the scattering plane:

C NN =

1 ( LL)( RL) + ( LR )( RR ) − ( LL)( RR ) − ( LR )( RL)
Pb Pt ( LL)( RL) + ( LR )( RR ) + ( LL)( RR ) + ( LR)( RL)
LL

Pk

A
LR
RL

Pp

A

RR

November 2005

P.11

LEXFOR

Polarization (continued)
REACTION Coding: Modifier C in SF8, and a branch code in SF5 giving components ofbeam and target spin.
Example:
LL,POL/DA,,C

CLL, spin correlation function, outgoing particle and recoil nucleus
spins parallel to beam direction in scattering plane

If time reversal holds: CNN = ANN.
Spin-Rotation-Depolarization Parameters (Dik or Di,0,k,0 for incident beam and Djp or
D0,j,0,p for target)
The spin-rotation parameter is a measure of the rotation of the spin of the scattered beam.
The three orthogonal components of the outgoing particle polarization are related to thecomponents of the incident particle polarization through the set of spin-rotation parameters.
These parameters are related to the Wolfensein [1956Wo] parameters as follows:
Wolfenstein
Parameter
DNN =

D

DSS =

R

DLS =

R′

DSL =

A

DLL =

A′

Representation⊗ signifies normal to the scattering plane

DNN is also known as the Spin-Depolarization Parameter
REACTION Coding: Modifier D in SF8, and a branch code in SF5 giving components ofbeam and target spin.
Example:P.12

LL,POL/DA,,D

Spin-Rotation Parameter DLL, beam and scattered particle spins
parallel to beam direction in scattering plane.

LL,POL/DA,*,D

Spin-Rotation Parameter DLL, target and recoil nucleus spins
parallel to beam direction in scattering plane.

November 2005

LEXFOR

Polarization (continued)
Spin-flip Parameter (Skp or S0,0,k,p): spin flip parameters.
REACTION Coding: Modifier S in SF8, and a branch code in SF5 giving components ofbeam and target spin.
Example:NN,POL/DA,,SF

Spin-flip probability (Snn)

The Spin-Flip Probability is related to the spin depolarization parameter by:
S flip = 1 2 (1 − DNN )Spin-Rotation Function (SRF or Q): gives the coupling between the longitudinalcomponent of the beam polarization and the component of the outgoing particle spin
Q = 1 − P 2 sin βperpendicular to the beam direction.
where β is the angle through which the projection of the polarization upon the scattering
plane is rotated.
For spin-0 particles:
Q = A cosθ lab + R sin θ lab = DSL cosθ lab + DSS cos θ lab
REACTION coding: POL/DA,,SRF
Spin-Transfer Parameter (Kip for incident beam and Kjk for target)
3

Pb
Examples:
NN,POL/DA,,K

KNN, spin transfer parameter, incoming particle and recoil
nucleus spins normal to scattering plane

KLL, spin transfer parameter, target nucleus and outgoingparticle spins longitudinal in scattering plane
The spin-transfer parameter is related to the spin-rotation parameter by:.
LL,POL/DA,*,K

Dij (θ ) = Kij (π − θ )Total Spin-TransferLVXVHGDVDQLQGH[WRGLVWLQJXLVKVSLQIOLS 6  DQGQRQVSLQIOLS
6  H[FLWDWLRQ7KHTXDQWLW\LVGHILQHGDVΣ = 3 − ( DSS + DNN + DLL ) / 4 = ( S SS + S NN + S LL ) / 2
REACTION coding: (……,,POL/DA,,TST)

November 2005

P.13

LEXFOR

Polarization (continued)
II. Quantities given in Spherical Coordinates
Madison convention for spin-1 particles quantities given in spherical coordinates4
The following subscripts are defined:k refers to the rank
q refers to the projection
For particles of spin ≥ 1, the polarization may be described in terms of tensor quantities ofinteger rank k ≥ 2i; 0 ≤ |q| ≤ k.
The differential cross section for a reaction initiated by a beam with tensor components t kq is(σ = σ 0 ∑ k ,q tkqTkq*)

If parity is conserved, T10=0, T11 is pure imaginary, and T2q is pure real.
For projectiles of spin 1 the cross section may be written asσ = σ 0 [1 + 2iT11 Re(t11 ) + T20t20 + 2T21 Re(t21 ) + 2T22 Re(t22 )]For projectiles of spin 3/2 three third rank tensors complete the set: T31, T32, and T33.
Polarization (tkq) (Not presently compiled).
Analyzing Power (Tkq)
Vector analyzing power (iT11)
REACTION Coding: quantity code VAP in SF6
Example: (……,,POL/DA,,VAP)
Tensor analyzing power (T20, T21, T22, etc.)
REACTION Coding:quantity code TAP in SF6; k and q are specified under the
branch field using the codes 20, 21, etc.
Example: (……,20,POL/DA,,TAP)
Data presented in the technical transversity coordinate frame are written with the superscript
T, i.e., TTkq. T T10 = 2 iT11 .
These are not presently defined in EXFOR.

4

See [1971Sa].

P.14

November 2005

LEXFOR

Polarization (continued)
III. Associated Information
Polarized beam specification
For a polarized incident neutron beam, enter the code POLNS under the keyword
INC−SOURCE; for a polarized ion beam, enter POLIS. If the incident source is known, it
should follow in the same set of parenthesis.
Example: INC-SOURCE(POLNS,D-T)

Atomic beam and Lamb-shift sources are entered using the codes ATOMI and LAMB,
respectively.
Polarized target specification
For a polarized target, enter the code POLTR under the keyword INC-SOURCE.
The polarization of the incident beam and target should be given in the data table, if known,
using the data headings POL-BM and POL-TR, respectively. The numerical uncertainties areentered using the headings POL-BM-ERR and POL-TR-ERR; an explanation may be given
in free text under ERR-ANALYS (see EXFOR Manual, Chapter 7, ERR-ANALYS).

REFERENCES
1956Wo1960Hu1963We1970Ma1971Sa1972Oh1978As

1981Oh1992FiL. Wolfenstein, Polarization of fast nucleons, Ann. Rev. Nucl. Sci. 6, (1956) 43.
Proceedings of the International Symposium on Polarization Phenomena of
Nucleons, P.Huber and K. P. Meyer, eds., Helv. Phys.Acta, Suppl. VI (1960).
T. A. Welton, The theory of polarization in reactions and scattering, Fast
Neutron Physics, Part II (Interscience Publishers, 1963) 1317.
P. Marmier and E. Sheldon, Physics of Nuclei and Particles, (Academic Press,
NY, 1970) Vol. II, Ch. 13.
G. R. Satchler et al., Polarization Phenomena in Nuclear Reactions (The
University of Wisconsin Press, Madison, WI, 1971) pp. xxv-xxix; see also S. E.
Darden, pp. 39-56.
G. G. Ohlsen, Polarization transfer and spin correlation experiments in nuclear
physics, Rep. Prog. Phys. 35,(1972) 717-801.
J. Ashkin et al., Convention for spin parameters in high energy scatteringexperiments, Higher Energy Polarized Proton Beams (American Institute ofPhysics, 1978).
D. Crabb, Spin correlation measurements in nucleon-nucleon scattering at highenergy, Polarization Phenomena in Nuclear Physics - 1980, (American Instituteof Physics, 1981).
D. Fick, G. Grawert, I.M. Turkiewicz, Nuclear physics with polarized heavy ions,Phys. Rep. 214 (1992) 1-111.

November 2005

P.15

LEXFOR

Production and Emission Cross Sections
Definition: The production cross section for a particle Y is defined as the sum of allenergetically possible reactions resulting in the production of at least one particle Y in theexit channels, each reaction weighted by the multiplicity of particle Y. The interactions
involved and their multiplicity need not be known.
The term emission cross section is defined as a special case and excludes elastic scattering.
Where the incident projectile is not equal to Y, the production and emission cross sections areequal.
These quantities are sum cross sections, which should be used only when two or morereactions producing particle Y are energetically possible.
Sum rules:

neutron production = neutron emission + elastic
neutron emission = (n,n’) + 2(n,2n) + 3(n,3n) + (n,np)……+ ν (n,f)

REACTION Coding:
Production cross section: code X in SF3 (Process).
Emission cross section: code X in SF3, code EM in SF5 (Branch).
The product measured is coded either in reaction SF4, or as a variable in the data table (seeEXFOR Manual Chapter 6: Variable Nucleus).
For inelastic gamma emission, see Scattering: Inelastic.
Examples:(…(P,X)0-G-0,,SIG)(…(N,X)0-NN-1,EM,SIG)(…(N,X)ELEM/MASS,,SIG)(…(P,X)NPART,NUM,PY,P)

proton-induced gamma-production cross section
neutron-induced neutron emission cross section
neutron-induced isotope production cross section
yield for production of n protons with n given in thedata table under the heading PART-OUT

For isotope production on a natural target, the reaction is coded as:(Z-S-0(…,X)Z'-S'-A',,SIG)(Z-S-A(…,X)Z'-S'-A',,SIG,,A)

if only one reaction is possible.

Probability for emission of n particles
REACTION Coding: code X in SF3, code NPART in SF4, and code EM/NUM in SF5(Branch). The particle measured is given in SF7
Example:(…(…,X)NPART,EM/NUM,SIG,A)

The number of particles is given in the DATA section under the data heading PART-OUT
with units of NO-DIM.
See Particles: Variable number of emitted particles.

P.16

November 2005

LEXFOR

Production and Emission Cross Sections (continued)
Unweighted production cross section. Sometimes the arithmetic sum of all reactions
resulting in the production of one or more outgoing particles Y is given without weighting by
the multiplicity of Y.
If only a few reactions are contributing in the energy range measured, the quantity can begiven as an explicit sum of these reactions. However, if more than 2-3 reactions contribute,the data are coded as a production cross section with the branch code UNW in SF5.
Example: (…(G,X)0-NN-1,UNW,SIG) = ( Q  Q  QS  Q Products

November 2005

P.17

LEXFOR

Products
Products of 2 or more reactions can be expressed as a reaction combination using theseparator * (see EXFOR Manual, page 6.6.)
Example:REACTION((42-MO-98(N,TOT),,WID)*(42-MO-98(N,EL),,WID))

Products implicit in the quantity codes
For certain products that be measured directly, or are frequently used, special quantities havebeen introduced. The following factors are coded using special codes in reaction SF8(modifier):S0
σ0 (peak cross section at resonance)
A, (A)a (isotopic abundance);(A) = uncertain if multiplied by abundance (see General
Quantity Modifiers)
G,AG,2G,2AG,4AG
g, ag, 2g, 2ag, 4ag (g = statistical weight factor)
RTE
E
4PI
4
SQ
(…)2
RS
4  elFCTfactor to be defined in free text (see General Quantity Modifiers)(See also Fitting Coefficients).

P.18

November 2005

LEXFOR

Quantum Numbers
Resonance levels in compound nuclei
Momentum lorbital angular momentum of neutrons exciting a compound-nucleus
resonance
Resonance spin J total spin value of the compound-nucleus resonanceParityparity of a compound-nucleus resonance
Statistical weight g statistical weight of a compound-nucleus resonance:

g=
where

( 2 J + 1)
( 2i + 1)( 2 I + 1)

i = spin of incident projectile
I = spin of target nucleus

These quantum numbers can be entered in two different ways:
1. Quantum numbers are assumed as parameters of strength functions, reduced neutron
width, or other quantities. These are entered as parameters in an additional field of the datatable, either in the COMMON or in the DATA section, under the data headings: MOMENTUM
L, SPIN J, PARITY, STAT-W G.
Example:DATA
MOMENTUM L
NO-DIM
1.0…
ENDDATASPIN J
NO-DIM
0.5

PARITY
NO-DIM-1.0

STAT-W G
NO-DIM
1.5

DATA
MILLI-EV…

2. Quantum number that is the result of the resonance parameter analysis. One of thefollowing reaction codes is used:(…(N,0),,L)(…(N,0),,J)(…(N,0),,PTY)(…(N,0),,SWG)
In this case the data are entered into the data table under the data heading DATA, and the data
unit NO-DIM.
Quantum numbers, when entered in the DATA table, should be entered with the decimal
point (in the case of parity as 1. or -1.).
The statistical weight factor may also be used as modifier in the quantity code (REACTION
SF8) for resonance parameters (see Products).

November 2005

Q.1

LEXFOR

Quantum Numbers (continued)
Excited states in product nuclei (see also Isobaric Analog States).
When an excited state is defined in a reference by its quantum numbers:
spin J
the spin value of a level in a product nucleus,
paritythe parity of a level in a product nucleus,
these quantum numbers may be entered in the BIB section under the keyword LEVEL-PROP
to define the level for which the data are measured (see also EXFOR Manual Chapter 7,
LEVEL-PROP). These properties may be associated with specific data lines in one of thefollowing ways.
1. Through the level energy (which may be assigned by the compiler).
Example:BIB
LEVEL-PROP
ENDBIBNOCOMMON
DATA
EN
MEV
1.
1.
2.
ENDDATA(26-FE-56,E-LVL=0.845,SPIN=2.,PARITY=+1.)(26-FE-56,E-LVL=2.085,SPIN=4.,PARITY=+1.)

E-LVL
MEV
0.845
2.085
0.845

DATA
MB
…
…
…

2. Through the level number (which may be assigned by the compiler).
Example:BIB
LEVEL-PROP
ENDBIBNOCOMMON
DATA
EN
MEV
1.
2.
1.
ENDDATA(26-FE-56,LVL-NUMB=1.,SPIN=2.,PARITY=+1.)(26-FE-56,LVL-NUMB=2.,SPIN=4.,PARITY=+1.)

LVL-NUMB
NO-DIM
1.
1.
2.

DATA
MB
…
…
…

3. Using flags.
Example:BIB
LEVEL-PROP
ENDBIBNOCOMMON
DATA
EN
MEV
1.
2.
1.
ENDDATA

Q.2((1.)26-FE-56,,SPIN=2.,PARITY=+1.)((2.)26-FE-56,,SPIN=4.,PARITY=+1.)

DATA
MB
…
…
…
…

LVL-FLAG
NO-DIM1.
1.
2.

November 2005

LEXFOR

RatiosRatios of 2 or more reactions can be expressed as a reaction combination using theseparator ’/’ (see EXFOR Manual Chapter 6).
Units: NO-DIM
Example:((3-LI-6(N,T)2-HE-4,,SIG)/(92-U-235(N,F),,SIG))

Ratio of reactions with different independent variables. In the case where the numerator
and denominator of the reaction ratio refer to different values for one or more of the
independent variables, the separator ’//’ is used. The independent variables that differ are
coded in the data table using data headings with the extension -NM and -DN for thenumerator and denominator, respectively.
Example:REACTION
ENDBIB
COMMONE-LVL-NMMEV…
ENDCOMMON((13-AL-27(N,INL)13-AL-27,PAR,SIG)//(13-AL-27(N,INL)13-AL-27,PAR,SIG))

E-LVL-DN
MEV…

Ratios implicit in the quantity codes.
For certain frequently used ratios, special quantity codes have been introduced.
ALF (SF6) = capture-to-fission ratio (see Absorption: Alpha)ETA (SF6) = average neutron yield/nonelastic event (see Neutron Yield)
RS (SF8) = 4 HODVWLFVFDWWHULQJFURVVVHFWLRQ
Isomeric Ratios are coded using the separator ’/’ in the isomer field of the reaction product(SF4), and with the modifier RAT in SF6. (See Isomeric States.)
REACTION Parameter Code RAT
The code RAT in reaction SF6 is given for, and only for• isomeric ratios, i.e., when the separator ’/’ appears in the isomer extension of the reaction
product (see above).
• binary to ternary fission ratios, i.e., when SF5 contains the codes TER/BIN or BIN/TER.

November 2005

R.1

LEXFOR

Raw Data
Definition: "Raw" data are experimental data that are not yet reduced to the final form but
still contain, for example, contributions from detector efficiency, instrumental resolution, or
sample thickness.
Although such data may be of little use to usual data center customers, it has been recognizedthat "raw" data should be stored by the data centers. Such data would then be available:• for re-analysis when improvements in analysis techniques are made• for realistic assessments of data errors as they become increasingly important toevaluators,1• for resonance analysis.
Self-indication measurement: see Self-Indication
Transmission measurement: see Total.
Reaction yields:

where:(

yr = 1 − e− nσ T)σr ∞+ ∑ yr ,i
σ T i =1<…> denotes resolution broadening
n is the sample thickness in nuclei/barn
T and r are the Doppler-broadened, abundance-weighted total and partial
reaction cross sections, respectively
yr,i is the reaction yield from neutrons scattered i times before inducing thereaction of type r, e.g., fission, scattering or radiative capture.

Note that the following simple relationship with the (broadened) cross section exists for thinsamples (n σT <<1) :1
1
yr ≅ σ rln e −nσ T ≅ σ T ;nnData may be given as counts or as uncorrected cross sections in barns.
−

The data may be transmitted in EXFOR using the modifier RAW in REACTION SF8; it should
always be explained in free text.
Additional data types may be added as they are encountered.
Voluminous files of "raw" data may be stored on special archival tapes. (See EXFOR
Manual Appendix B). An EXFOR entry is then transmitted, using the keyword STATUS togive a cross-reference to the special archival file, the approximate number of data records,
and information on how to request the data. If appropriate, a warning should be given in freetext that the raw data should be used only after consultation with the author.

1

See recommendation by the NEANDC/NEACRP meeting on neutron data for structural materials, Geel,
December 1977.

R.2

November 2005

LEXFOR

Raw Data (continued)
The BIB section of the entry should be prepared as usual, containing at least the obligatory
keywords (see EXFOR Manual Chapter 7). A data subentry should be included for each setof raw data stored; the BIB section should include, at minimum, the reaction.
COMMON section should contain minimum and maximum of the incident-projectile energy.
The system identifier NODATA replaces the DATA section (see EXFOR Manual Chapter 2).

November 2005

R.3

LEXFOR

Reaction Mechanisms
An author may assign fractions of a measured cross section to different reaction mechanisms.
The following reaction mechanisms are defined, based on currently accepted nuclear models,and may be entered into EXFOR in the manner described on the following pages.
These partial cross sections cannot be measured directly but are deduced from theoreticalconsiderations2. Therefore, careful explanation in free text is required whenever thesequantities are given.
Compound-Nucleus Interaction and Direct Interaction:
1. Compound-Nucleus Interaction: A reaction in which the incident projectile is absorbed by
the target nucleus and its initial energy is assumed to be shared by all other nucleons, suchthat the mode of disintegration of the "compound nucleus" is independent of the way inwhich it was produced.
2. Direct Interaction: A reaction in which there is direct interaction between the incident
projectile and single nucleons or clusters of nucleons in the target.
Some reactions may proceed by either mechanism, in which case the total reaction is equal to
the sum of the compound-nucleus interaction and direct interaction portions. In this case, thepartial cross sections for the compound-nucleus interaction and direct interaction portions ofa reaction may be coded with the modifiers CN and DI, respectively, in SF5 (branch) for the
keyword reaction.
Examples:(…(N,P),CN,SIG) Compound nucleus portion of (n,p) cross section(…(N,P),DI,SIG) Direct interaction portion of (n,p) cross section
High-energy and Low-energy Components of Cross Section The higher and lower
components of the "configurational splitting" of the giant dipole resonance include the sum of
the cross sections for a number of different reactions with different outgoing particle
energies. These data are often presented in evaluations as a "high-energy" and "low-energy"
component of the secondary particle spectrum.
The "high-energy” component is due to the nucleon transitions from the lower filled shells of
the nucleus to unfilled valence shells. The "low-energy" component is due to the nucleon
transitions from the unfilled valence shell of the nucleus to various empty upper shells. The
difference between the centers-of-gravity of two such components defines the energy value
for the configurational splitting.
In this case, the partial quantity for these components may be coded under the keyword
REACTION using the branch codes HEN and LEN in SF5. The contributing reactions may be
defined in free text.
Examples:(…(G,ABS),HEN,SIG) High-energy component of photo-absorption cross section(…(G,ABS),LEN,SIG)
Low-energy component of photo-absorption cross section
2

These reactions are partial, therefore, if the reaction proceeds totally through one branch, no modifier is used.

R.4

November 2005

LEXFOR

Reaction Mechanisms (continued)
Fusion, Fast Fission, and Deep Inelastic Scattering [1]For heavy ion reactions under suitable conditions, the incident projectile can penetrate thetarget and a deeply elongated compound nucleus is formed. If the system lives long enough tocompletely randomize, it results in a compound nucleus in an excited state. This result iscalled fusion. The data are coded using the process code FUS in REACTION SF3
Example:(…(P,FUS),,SIG)

The case where the nucleus is formed, that is the kinetic energy of the incident projectile isconverted into internal energy, but breaks apart after about a 90-degree rotation, is called
deep inelastic scattering3.
An intermediate situation, in which complete rotations occur but the system does not fuse(i.e., it breaks apart), is called fast fission. The data are coded using the process code F in
REACTION SF3 as for fission at lower energies. (See Fission).
The spectrum of reactions as a function of increasing interaction time (decreasing angularmomentum) proceeds from elastic scattering and Coulomb excitation to quasi-elastic to deep
inelastic to fast fission to fusion; although the boundaries between these processes are notwell defined.
Spallation and High-energy Fission4
As the bombarding energy becomes high (~100 MeV/nucleon), a series of individual
nucleons, or small groups of nucleons, may be ejected (spallation) or the target may breakinto several large fragments (fragmentation or fission).
In spallation several particles are ejected from the target nucleus by direct interaction leaving
behind a nucleus in an excited state, which then evaporates nucleons or clusters of nucleons.
In fission the incident projectile penetrates the target and a compound nucleus is formed,
which then breaks apart.
High-energy Fission (energies > about 50 MeV) proceeds in essentially the same manner as
spallation except that the excited nucleus divides into roughly two fragments.
In this case, where the measured product yield has been separated into to its fission andspallation components by the author, the partial quantity spallation or fission may be coded
under the keyword reaction using the branch codes SPL and FIS, respectively, in SF5.
Examples:(82-PB-208(92-U-238,X)31-GA-69,SPL,SIG)(82-PB-208(92-U-238,X)31-GA-69,FIS,SIG)
See Fission for fission process at lower energies.
For the production of specified product nuclei see Product Yields and Production andEmission Cross Sections.

3

If these data are compiled, a branch code should be proposed.
If the author measures the total break-up or production of a given product and states that this reaction is totally
due to spallation or to fission, then the codes SPL or FIS must not be given because these designate partial
reactions.
4November 2005

R.5

LEXFOR

Reaction Mechanisms (continued)
Reference[1]

H. Feshbach, Theoretical Nuclear Physics: Nuclear Reactions (John Wiley and Sons,
1992) Chapter VIII, Heavy Ions.

R.6

November 2005

LEXFOR

Reaction ProductDefinition: In general, the heaviest of all identifiable products of the reaction specified isdefined as the Reaction Product (also called the residual nucleus) and is entered into SF4 ofthe reaction keyword.
See EXFOR Manual Chapter 6 for a complete discussion of the use of the Reaction Productsubfield, including coding rules.
If no isomer code is given, then the reaction is to a nucleus in the ground state and includes
decays from isomeric states. If an isomer code is given, a partial reaction for the formation ofthat isomeric state is given, and, in general, decays from higher isomeric states are notincluded. (See Isomeric States).
In the case of product yield data or production cross sections for which the reaction
specified may lead to the production of more than one reaction product, the Variable Nucleus
Formalism may be used (see EXFOR Manual Chapter 6).
A description of the decay information about the reaction product may be given using theinformation-identifier keyword DECAY-DATA (see Decay Data). This information should
always be given, where known, for an activation measurement or for a nucleus in an isomericstate.

November 2005

R.7

LEXFOR

Reference
Information-Identifer Keyword REFERENCE. All bibliographic references which contain
information of importance directly relating to the data compiled in EXFOR, i.e., not only thereference from which the data were taken, but also other important references, such as journal
articles, conference papers, and laboratory reports may be coded under the keyword
REFERENCE. Progress reports and abstracts should, in general, be excluded, if they containno additional useful information. The primary reference, in general, the published reference,
this should be given first, as this is the reference that will be used when referring to the data.
A reference (or the first reference) given in a data subentry, supersedes any reference given in
subentry 1 as the primary reference.
Other related references must not be coded under this keyword, but may be coded under the
keywords REL-REF or MONIT-REF (see following page).
For the coding rules see EXFOR Manual Chapter 7: REL-REF and MONIT-REF.
The purpose of the bibliography is½ to help compilers:• avoid duplicate entry of data in EXFOR,• identify a data set when data are requested by reference;½ to help users of EXFOR:• get easy access to any additional information available in the published references,• check whether a given reference has been considered by the compiler.
Therefore, the free text should indicate to users of EXFOR:• the main reference.
• the kind of information contained in each reference given, e.g., "instrumentation only","graphs only", "no data", "theoretical analysis", etc.
When translations of references exist, these should be included also, for the convenience ofusers of EXFOR.
Important references which are published after the first compilation of the EXFOR entry,
should be added subsequently and the entry retransmitted as specified in EXFOR Manual
Chapter 8. Usually such a new reference will provide additional information on theexperiment or the numerical data, which should be added and retransmitted simultaneously.
When referencing a document that has more than one document code, the primary code (i.e.,the document code assigned by the originating laboratory) should be given first, in mostcases. The main exceptions are reports issued by advisory committees where the agencyassigned number is the primary report number.

R.8

November 2005

LEXFOR

Reference (continued)
Private Communications If data are received via a private communication, thecorrespondent and the date of the private communication may be entered as a reference (seeEXFOR Manual Chapter 7: REFERENCE) or under the information-identifier keyword
STATUS5.
Conferences. If conference proceedings are issued within a report series, so that they can be
identified with a report number, then the report number must be used, not the conference
code. The date given is the date of the report.
Example:REFERENCE(S,IAEA-107,196802)

The proceedings of the standards panel
67BRUSSELS issued as report IAEA-107.

Paper Number. If two or more papers start on the same page of a given reference, theyshould be differentiated in the paper number field. If no paper number is given, the papers
should be numbered sequentially.
Example:(J,PR,104,482(1),5612)(J,PR,104,482(2),5612)

first paper on page 482 of Phys. Rev., 104
second paper on page 482 of Phys. Rev., 104

Information-Identifier Keyword REL-REF. A reference relating to, but not directly
pertaining to the data given, may be entered under REL-REF. Examples are critical remarks
or corrections applied by another author, e.g., within a data review or evaluation. (SeeEXFOR Manual Chapter 7: REL-REF, for coding rules.)Information-Identifier Keyword MONIT-REF. References from which the standard (ormonitor) data used in the experiment were taken are coded under MONIT-REF. (SeeEXFOR Manual Chapter 7: MONIT-REF for coding rules.)5This is preferred, if there is a published reference.

November 2005

R.9

LEXFOR

Resolution
Incident-projectile Energy Resolution:
combination) of the incident projectile.

the energy spread or channel width (or aThe energy resolution describes the distribution curve of the energy spread. It is usually
defined as full-width at half-maximum (FWHM), but may be given in other representations.
The shape and definition of the resolution function should be given in free text under INCSPECT, if known.
Resolution is coded using the following data headings:
EN-RSL-FW
Incident-particle energy resolution (FWHM)
EN-RSL-HW
Incident-particle energy resolution (±HWHM)
EN-RSL
Incident-particle energy resolution (unspecified)
The energy resolution can be given in energy units, in percent, or in units of a reciprocal
velocity (e.g., NSEC/M).
Example:EN-RSL-FW: Energy resolution = 2 MeV
EN-RSL-HW: Energy = 1. MeV
3. 4. 5.
Energy (MeV)

Note: The terms resolution and error are often misused in the literature. Distinguish between
them, where possible. See Errors.
Secondary-energy resolution: the energy spread of an outgoing (secondary) particle (seeSecondary Particles).
Angular resolution: the angular spread of an outgoing (secondary) particle (see Angle).

R.10

November 2005

LEXFOR

Resonance Integral
Definition: Effective cross section of the epithermal part of a reactor flux.
REACTION coding: RI in SF6 (Parameter)
Units: a code from Dictionary 25 with the dimension B (e.g., B)
Example: (…(N,ABS),,RI)
The energy limits are specified under the data headings EN-MIN and EN-MAX.
Infinitely dilute resonance integrals for a 1/E spectrum are defined as:
∞

dE
Ec
E
where Ec = cutoff energy near the lower limit of the epithermal region.
Ir = ∫ σ r (E)These are usually measured as cadmium ratios where ECd is the cadmium cutoff energy,
which is dependent on the thickness of the cadmium cover.
In some cases, an upper limit is given for the energy (e.g., 10 MeV) and should be coded.
When an upper limit is not given, en-max may be omitted.
For further details, see Baumann [1] and Scoville [2].
Resonance integrals over smaller energy ranges, where the sum over the partial energy
ranges given from the cutoff energy to the maximum energy is equal to the total resonanceintegral, should be coded with the quantity modifier LIM in reaction SF8.
Reduced resonance integrals, where the 1/v part has been subtracted, should be coded with
the quantity modifier RNV in reaction SF8.
Resonance integrals calculated from resonance parameters should be entered using thecode DERIV in reaction SF9 (data type). See also Data Type.
Effective Resonance Energies. The ’ideal’ resonance integral is defined for an epithermal
flux as being proportional to 1/E. This is an approximation that may be sufficiently accurate
only in certain cases. Directly measured resonance integrals and those computed from crosssection curves assuming a 1/E flux are often discrepant due to the fact that realistic
epithermal fluxes deviate from the 1/E shape.
Ryves has developed a better approximation, which is sufficiently accurate for mostapplications, in which the epithermal part of the reactor neutron spectrum is proportional to
1/E1+ ..

November 2005

R.11

LEXFOR

Resonance Integral (continued)
Accordingly, the realistic resonance integral is defined as:∞ σ ( E ) dE / eV
I (α ) = ∫1+α0( Ec / eV )where a constant close to zero (either positive or negative) which can be
determined for each reactor spectrum
Ec = cutoff energy near the lower limit of the epithermal)RU  WKLVIRUPXODJRHVWRWKHLGHDOLQILQLWHGLOXWHUHVRQDQFHLQWHJUDO
∞σ ( E )dEEE

I0 = ∫c

The realistic resonance integral (α ≠ 0) and the ’ideal’ resonance integral (α = 0) are relatedby:I (α ) =I 0 − 0.429σ 0(E / eV )

α

r

where

+

0.429σ 0(2α + 1)(Ec / eV )α0 = 2200 m/sec cross section
Er = effective resonance energy

The effective resonance energy is a microscopic nuclear constant representing a kind of
average over the major resonances. It is tabulated in the literature and can be determined byexperiment and evaluation.
Note: For (n DFWLYDWLRQDQDO\VLVWKHHIIHFWLYHUHVRQDQFHHQHUJ\LVQHHGHGDVDFRUUHFWLRQ
factor of similar importance to the resonance integral. Its value need not be known withhigh accuracy; a 50% uncertainty in the effective resonance energy may lead to a 1%
XQFHUWDLQW\ LQ DFWLYDWLRQ DQDO\VLV PHDVXUHPHQWV ZKHUHDV LJQRULQJ WKH SDUDPHWHU  PD\
lead to a 25% error in the measurements.
When directly measured resonance-integral data are compiled in EXFOR, it is essential• WR JLYH DOO DYDLODEOH LQIRUPDWLRQ RQ WKH HSLWKHUPDO QHXWURQ VSHFWUXP DQG WR TXRWH WKHparameter if given• to state whether the resonance integral given is for the realistic epithermal neutron
spectrum, or whether appropriate corrections have been applied so that the value given is forthe ideal epithermal 1/E spectrum.
For further information see Ryves [3], Simonits [4], Jovanovic [5].

R.12

November 2005

LEXFOR

Resonance Integral (continued)
References[1.] N. P. Baumann, Resonance integrals and self-shielding factors for detector foils,
duPont Savannah River Laboratory report DP-817 (1963)[2.] J. J. Scoville and J. W. Rogers, Topical report: resonance integrals measured in theadvanced reactivity measurements facilities, Idaho Nuclear Corporation report IN-1195(1968)[3.] T. B. Ryves, A New Thermal Flux Convention, Metrologia 5, 119 (1969)[4.] A. Simonits, F. deCorte, L. Moens, J. Hoste, J. Radioanal. Chem. 72, 209 (1982); seepage 215.
[5.] S. Jovanovic, F. deCorte, L. Moens, A. Simonits, J. Hoste, J. Radioanal. Chem. 82#2,
379 (1984).

November 2005

R.13

LEXFOR(Blank page)

R.14

November 2005

LEXFOR

SampleProperties of the sample used in the experiment are coded, in general, as free text under the
Information-Identifier Keyword SAMPLE. Information on chemical composition, sample
thickness, isotopic composition, etc., should be entered if known. Sample thickness andsample temperature may alternately be entered into the data tables.
Sample thickness
In the case of sample thickness, especially if data are measured for more than one thickness,the sample thickness may be entered into the DATA section using the heading THICKNESS.
Example:
DATA
EN
MEV
...
ENDDATA

DATA
B
...

THICKNESSATOMS/B...

Sample temperature
At low energies, the data may be dependent on the temperature of the sample. In this case,the data should be coded using the parameter code TMP in REACTION SF6. The sample
temperature is coded in the data section under the Heading TEMP.
Example:BIB
REACTION…
ENDBIB
COMMONTEMPK300.
ENDCOMMONDATAEN…
ENDDATA

November 2005

(1-H-1(N,TOT),,SIG/TMP)

DATA…

DATA-ERR…

S.1

LEXFOR

Scattering(See also Differential Data, Thermal Scattering).
Definition: Two-body interaction with only one particle, which is the same as the incident
particle, in the exit channel.
The following scattering processes are defined:
1. Total Scattering. The sum of all scattering interactions.
Sum Rule: Total scattering = elastic scattering plus inelastic scattering= total minus absorption
REACTION Coding: SCT in SF3 (Process).
Example: (.....(P,SCT)...,,SIG)
The following formalism is no longer used; instead use SCT in SF3.
(....(P,P)...,,SIG)
used only when the scattering type need not be
distinguished.
Note: In some experiments (e.g., Lane1), the data may be called scattering even though theyextend above a threshold where other reactions producing the scattered particle are also
possible. Whether such data have to be corrected for the effects of such threshold reactions
should be specified. If they were not, the quantity should be coded as neutron production.
2. Elastic Scattering. Scattering without excitation of the scattering nucleus (Q = O).
REACTION Coding: EL in SF3 (Process).
Example: (...(N,EL)...,,DA)
3. Inelastic Scattering. Two-body interaction in which the incident projectile re-emerges
with an energy less than its’ initial energy by the amount of energy deposited in the target
nucleus (Q < O). The residual nucleus is left in an excited state, which then decays, primarily,
E\ UD\HPLVVLRQ
Method of Measurement. Inelastic scattering may be measured by detecting the inelastically
VFDWWHUHG SDUWLFOH RU E\ GHWHFWLQJ WKH GHH[FLWDWLRQ  UDGLDWLRQ 'XH WR UD\ FDVFDGHV WKH
SURGXFWLRQRIDVSHFLILF UD\PD\GLIIHUIURPWKHH[FLWDWLRQRILWVVWDWHRIRULJLQ7KH\ZLOO
EHHTXDOKRZHYHULI UD\FDVFDGHVWRDQGIURPWKHOHYHOFDQEHH[FOXGHG
REACTION Coding: INL in SF3 (Process).
)RULQHODVWLF HPLVVLRQG is coded in SF7 (Particle considered).
)RUSDUWLDOUHDFWLRQVGXHWRWKHH[FLWDWLRQRIDGLVFUHWHOHYHORUWKHSURGXFWLRQRIDVSHFLILF
ray, the code PAR is entered into SF5 (Branch).

1

Lane,et al., Phys. Rev. 107, 1077 (1957).

S.2

November 2005

LEXFOR

Scattering (continued)
For the excitation of a discrete level or group of levels, the level energy or excitation energy
must be given under the data heading E-LVL or E-EXC.
)RUWKHSURGXFWLRQRIDGLVFUHWHLQHODVWLFVFDWWHULQJFDVFDGH RUUDQJHRI VWKH UD\HQHUJ\
must be given under the data heading E.
See EXFOR Manual Chapter 4 for the coding of two or more unresolved levels.
Examples:(...(..,INL)...,,SIG)(...(..,INL)...,,SIG,G)

total inelastic-scattering cross section
totDOLQHODVWLF HPLVVLRQFURVVVHFWLRQ(= inelastic-scattering cross section)(...(..,INL)...,PAR,SIG)
partial inelastic-scattering cross section for theexcitation of a discrete level or range of levels(...(..,INL)...,PAR,SIG,G) partial cross section for the production of a
GLVFUHWHLQHODVWLF RUUDQJHRI ’s(...(..,INL)...,,DA)angular distribution of inelastically scatteredparticles(...(..,INL)...,,DA,G)
angular distribution of inelastic ’s(...(..,INL)...,,DE)energy distribution of inelastically scatteredparticles(...(..,INL)...,,DE,G)
energy spectrum of inelastic ’s(...(..,INL)...,,DA/DE)
double differential inelastic-scattering crosssection(...(..,INL+F)...,,SIG)
inelastic-scattering cross section to a fissionisomer

4. Potential Scattering: Elastic scattering that proceeds without the formation of anintermediate nucleus. (Elastic scattering is a mixture of potential and resonance scattering.)
REACTION Coding: POT in SF5 (Branch).
Example: (...(N,EL)...,POT,SIG)
5. Coulomb Scattering is defined as the elastic scattering of a charged particle under the
influence of the Coulomb force. Differential data are often given as a ration to Coulomb
scattering, since the scattering cross section approaches infinity at very small angles.
a.) Rutherford scattering, where the target is large with respect to the incident
projectile, is defined by:a dσ = dΩ  Rutherford 4 sin 2 θ

2

( 2)

November 2005

S.3

LEXFOR

Scattering (continued)b.) Mott Scattering, is applicable only to low-energy scattering of 2 like particles.

6. Thermal Scattering: Low energy scattering processes for which molecular andcrystalline forces are involved. See Thermal-Neutron Scattering.

S.4

November 2005

LEXFOR

Secondary Particles
See also Angle, Particles.
Secondary Energy
Information on the energy state of a nucleus after reaction, or on the energy value of detectedparticles, or on any other energy related to the secondary particles, is entered as follows:
1. Numerical values are entered in the COMMON or DATA section using data headings
from Dictionary 24 with the family code E, e.g., E-LVL, E.
a. In the case of two or more unresolved energy levels, the data heading may be repeated(see EXFOR Manual Chapter 4), or the energy range may be, e.g., E−LVL−MIN,
E−LVL−MAX.
b. If it is not evident to which reaction product the secondary energy refers, this must be
specified under the keyword EN-SEC; see below.
c. Only one representation of the secondary energy should be coded, therefore, if, e.g., a
UD\ HQHUJ\ LV JLYHQ DORQJ ZLWK WKH LQLWLDO DQG ILQDO H[FLWHG VWDWHV IRU WKH GHFD\ WKH
energy of the gamma is coded under the heading E and the headings LVL−INI and
LVL−FIN are used to give the levels as associated information.
d. In some cases, where the data is a function of the energy of two secondary particles,in order to reduce a 3-dimensional plot to two dimensions, the data are given as a functionof the distance along the kinematic locus of the energies (S). That is, the allowed energies
of particle 1 (E1) vs. particle 2 (E2) are described by a curve showing the kinematicallyallowed values of E1 vs. E2. The point of minimum energy of E1 is assigned the value S= 0. In this case the kinematic locus is entered under the heading S.

E2

S=0

E1
e. The secondary-energy uncertainty or resolution may be entered using a data headingfrom Dictionary 24 with the family code E, e.g., E-RSL, E-LVL-ERR. Further
information can be given under the keyword ERR-ANALYS (see EXFOR Manual Chapter
7: ERR-ANALYS). See also Errors, Resolution.

November 2005

S.5

LEXFOR

Secondary Particles (continued)
2. The information-identifier keyword EN-SEC may be used:• to specify to which reaction product the secondary energy given in the COMMON or
DATA section refers. (See EXFOR Manual Chapter 7: EN-SEC). This keyword must always
be coded when the data headings El, E2, etc., are used.
• to give free text information about the secondary energy.
A secondary-energy that is not defined2 by the REACTION code must be defined under the
keyword EN-SEC.
3. Energy Correlation of Secondary Particles: see Differential Data.
4. Average Kinetic Energy
REACTION Coding: AKE in SF6 (parameter)
Example:(.(G,X)O-NN-1,,AKE)

average kinetic energy of neutrons

5. Most Probable Kinetic Energy
REACTION Coding: KEP in SF6 (parameter)
Example: (.(P,F),,KEP,FF)

most probable kinetic energy of fission fragments(Secondary Effective Mass deleted).

Secondary Linear Momentum
Information about the linear momentum of a secondary particle may be entered as follows:
1. Numerical values are entered in the COMMON or DATA section using data headings
from Dictionary 24 with the family code L, e.g., MOM-SEC.
2. The information-identifier keyword MOM-SEC may be used:• to specify to which of several particles the secondary linear momentum given in the
COMMON or DATA section refers.
• to give free text information about secondary linear momentum.
A secondary-linear momentum that is not defined2 by the REACTION code must be defined
under the keyword MOM-SEC.
The keyword is always coded when more than one secondary linear momentum is given in
the COMMON or DATA section using the data headings MOM-SEC 1, MOM-SEC2, etc.
3. Quantities as a function of Linear Momentum of Secondary Particles: see Differential
Data.

2

That is, if the particle to which it applies is not obvious (See Particles).

S.6

November 2005

LEXFOR

Self Indication
It is often necessary to know some energy-averaged characteristics of elements of interest toreactor physics. One of such characteristics is self-indication functions (also called
transmission functions) and its dependence on the sample thickness. It is determined as

Tt ( x ) =∫ ϕ ( E )ε ( E )∆E−σ t ( E ) x

dE

(1)

∫ ϕ ( E )ε ( E )dE

∆E

where

( LVQHXWURQVSHFWUXPLQ (HQHUJ\LQWHUYDO ( LVGHWHFWRUHIILFLHQF\(E)
is total neutron cross-section, and x is the sample thickness.
t

The “Partial” transmission function Tp(x) is defined as follows:∫ ϕ ( E )σ ( E )−σ t ( E ) xp

T p ( x ) = ∆E

dE

(2)

∫ ϕ ( E )σ ( E )dE
p

∆E

where

p(E) is the cross-section of the process p (p = f, LQO etc.))RU NQRZQ (  DQG Tt(x), equations (1) and (2) represent a set of decoupled integral
equations of the first kind for determining cross-sections t(E) and p (E). After measuring of
the functions Tt(x) by the well-known experimental procedures [1] one may obtain t(E) fromequation (1). By measuring Tp(x), one can obtain p (E) from equation (2).
Using the energy group approximation formalism, one can obtain explicit expressions for the
subgroup representations ft(x) and fp(x) of the self-indication functions [2].
1  1 (σ t + σ 0 )(3)f t (σ 0 ) =
σ
−


0
σ t  1 (σ t + σ 0 )2


f p (σ 0 ) =1σp

 σ p (σ p + σ 0 )

σ
−

0
2
 1 (σ p + σ 0 )(4)where 0 is the so-called “dilution cross section” [2], i.e., the cross section for all admixture
isotopes in the sample.
REACTION coding: the modifier SIF/AV in SF8.
Examples: (74-W-0(N,TOT),,SIG,SIF/AV)3(74-W-0(N,F),,SIG,SIF/AV)

Total self-indication function
Self-indication function forfissionReferences
[1]
[2]

3

H.I. Liou et al., Phys. Rev., C7, 823 (1973) and references therein.
L. Abagjan et al., Group Constants for Nuclear Reactor Calculations, Atomizdat,
USSR (1964); translated by Consultants Bureau, NY, USA (1964).

Older data sets may have been compiled using the modifier RAW in place of SIF.

November 2005

S.7

LEXFOR

Single-Level Resonance Parameters
See also Average Resonance Parameters, Quantum Numbers, Multilevel ResonanceParameters.
Resonance cross sections as a function of energy may be described using a Breit-Wigner
single-level formalism.
For s-wave scattering the formula is:
2

Γ sct
R′
σ sc ( E ) = 4πλ g++ 4π R′2 (1 − g )( E − E0 ) + iΓ / 2 λ0
20

ZKHUH 5 2 =pot

For reactions (capture, fission, etc.):
1/ 2

E 
σ cc′ ( E ) = 4πλ02 g  0 
E
where

Γ c Γ c′( E − E0 ) + ( Γ 2 )22

c = channel for formation of compound nucleus
c′ = channel for decay of compound nucleus

For further detail see References 1 and 2.
Definitions and codes for data to be compiled in EXFOR.
(See Dictionary 36 (REACTION) for a complete list of codes.)Resonance Energy (E0) is coded in EXFOR in one of two ways.
1. When the resonance energy is determined by the author, it is assigned a REACTION codeand entered into the data table under the corresponding DATA field.
REACTION Coding: 0 (zero) in SF3 (process); EN in SF6 (parameter)
Example: (...(N,0),,EN)
2. When the resonance energy is not determined by the author, but is taken from othersources, it should be entered into the data table as an independent variable under the data
heading EN-RES. In this case, it should only be entered for those resonances for which theauthor has presented other resonance parameters.
Negative energy resonances, in many cases, will influence very low energy cross sections.
These bound levels should be coded with the negative energy, as given.

S.8

November 2005

LEXFOR

Single-Level Resonance Parameters (continued)
Resonance widths ( r)
REACTION Coding: WID in SF6 (parameter) and the code for the reaction described in SF3
Examples:(...N,TOT),,WID) = total width ((...(N,EL),,WID) = neutron width ( n)(...(N,G),,WID) = capture width, or radiation width (LQFOXGLQJDOOSULPDU\decays not followed by a neutron or charged-particle
emission.

Units: a code from Dictionary 25 with the dimension E (e.g., EV).
For partial radiation width, see Gamma Spectra.
Reduced neutron widths are defined at 1 eV as follows:
Γ0n =

Γn
E0 1eV

E0 is the resonance energy in eV.
vt is the penetration factor of the nucleus.
Or, more specifically:ΓnΓln =for s-wave resonances: (v0=1):
vt E0 1eV

(1)where:

Γ1n =for p-wave resonances:where:Γn1 
1 + 2 2 E0 1eV  k0 R 

(2)

(3)

k0 = wave number
R = nuclear radius

REACTION coding: (...(N,EL),,WID/RED)
The angular momentum should be specified under the data heading MOMENTUM L. (See
Quantum Numbers for coding of angular momentum).
Units: a code from Dictionary 25 with the dimension E (e.g., EV).
Note: Some authors give the reduced neutron width (for s-wave neutrons) as:
Γ 0n = Γ n

E0 ,which has the dimension of the square-root of an energy. (Compare: Hennies [3]). For
consistency, only definition (1) with the dimension of energy should be used in EXFOR, thenumerical values being anyway identical except for the dimensions.

November 2005

S.9

LEXFOR

Single-Level Resonance Parameters (continued)
Peak cross section is defined as a cross section at the peak of the resonance, assuming theline shape in a Breit-Wigner formalism, corrected (where important) for instrumental andtemperature effects. The peak cross section for s-wave neutrons can be expressed by:
Total:

σ 0 = 4πλ20 g

Partials:

σ 0 cc′ = σ 0ΓcΓΓc Γc′
Γ2

These are coded with the modifier code RES in combination with the code for the reaction
described.
Example:(...(N,TOT),,SIG,,RES) Total peak cross section

Resonance area is defined:
For scattering:

Asct = 2π 2 λ02 g

Γ 2c
ΓFor other reactions:Acc′ = 2π 2 λ02 g

Γ c Γ c′Γ

REACTION coding: the parameter code ARE in combination with the relevant reaction code.
Units: a code from Dictionary 25 with the dimension B*E (e.g., B*EV).
Example: (...(N,EL),,ARE) Scattering area
The quantity ( n  is often presented as a result of the resonance analysis and is
proportional to the capture area. It is coded the reaction combination followed by the
keyword RESULT, using the code CAPTA.
Units: a code from Dictionary 25 with the dimension E (e.g., EV).
Example:REACTIONRESULT

S.10(((....(N,EL),,WID,,G)*(....(N,G),,WID))/(....(N,TOT),,WID))(CAPTA)

November 2005

LEXFOR

Single-Level Resonance Parameters (continued)
Resonance Strength
The resonance strength is defined as:ωΓ =2J + 1Γ c Γ c′(2 ji + 1)(2 jt + 1) Γ

where:
J= spin of resonance,Ji= spin of incident projectile,
jt= spin of target,= partial width for formation of resonance,c= partial width for decay of resonance by reaction channel c′,c′= total width of resonance.
Resonance strengths are determined experimentally by measuring the area under the resonant
yield curve:ωΓ =where:λR
γ2ε Ac′Yr
λR Ac′ + Ac

= particle wavelength at the resonance energy,= stopping power

REACTION Coding: the parameter code, WID/STR in SF6.
Units: a code from Dictionary 25 with the dimension E, e.g., EV
Example: (...(P,A),,WID/STR)
Partial resonance strengths are given for transitions to a specific energy level.
Examples:(……(N,G),PAR,WID/STR)resonance strength for a given level excitation.
Some examples of special representations are as follows:
0 f
2
0

g n
ag n

(.....(N,F),,WID,,S0)(.....(N,TOT),,WID,,SQ/S0)(.....(N,EL),,WID,,G)
g = statistical weight factor(.....(N,EL),,WID,,AG)a = isotopic abundanceReferences
[1]
[2]
[3]

A. M. Lane and R. A. Thomas, Rev. Mod. Phys. 30, 257 (1958).
J. A. Harvey, ed., Experimental Neutron Resonance Spectroscopy (Academic Press,
1970).
Hennies, Nuclear Data for Reactors, Paris Conference, Vol. 2 (1966) page 333.

November 2005

S.11

LEXFOR

Spectrum Average
Cross sections averaged over a broad incident-projectile energy spectrum may be entered into
EXFOR using the proper modifier to REACTION SF84. The type of spectrum and its
characteristic should be entered in free text under the information-identifier keyword
INC−SPECT.
The following spectrum types are defined:
1. Maxwellian Average: Modifier MXW
The spectrum temperature should be given, if known. For thermal Maxwellian spectrum
averaged data, see Thermal Neutron Energies.
2. Epithermal Spectrum Average: Modifier EPI
The energy quoted will be, typically the low energy cutoff.
3. Fission-Neutron Spectrum Average: Modifier FIS
For details, see Fission-Neutron Spectra.
4. Fast Reactor Spectrum Average: Modifier FST
5. Bremsstrahlung Spectrum Average: Modifier BRA
The energy quoted will be, typically, maximum energy.
6. Average over part of Bremsstrahlung Spectrum: Modifier BRS
The energy quoted will be, typically, mean energy.
7. Spectrum Average (unspecified Spectrum): Modifier SPA
Used for all other spectra, e.g., thermal reactor spectra. Care should be taken to compile
only those data that would be of value to the user of EXFOR.
For pile or reactor spectrum, see Thermal Neutron Energies.
The spectrum energy should be entered into the data table using one of the following data
headings:
KT
spectrum temperature in units of energy
KT-T
spectrum temperature in units of temperature
EN-MEANmean energy
EN-DUMMY
dummy energy (characteristic of spectrum)
0.0253 eVthermal Maxwellian and thermal reactor spectra
1.5 MeVfission-neutron spectra
4.5 MeV
%HQHXWURQVRXUFHVNote: For Maxwellian spectra: E mean = 3 2 kT

4Cross sections measured as a function of energy and then averaged over a discrete energy range are entered as
average (modifier AV). See General Quantity Modifiers.

S.12

November 2005

LEXFOR

Spectrum Average (continued)
Data given relative to Maxwellian distribution at a given temperature
Spectrum data are sometimes given as a ratio to the value for a calculated spectrum at a given
temperature. These data are coded using the modifier code MXD in SF8; the sample
temperature for the Maxwellian distribution is given under the data heading KT-NRM.
Example:REACTION

November 2005

(98-CF-252(0,F),PR,DE,N,MXD)

S.13

LEXFOR

Standards(See also Dosimetry Reaction Data).
Standard and/or monitor information should be entered into an EXFOR data set using theinformation-identifier keyword MONITOR (see EXFOR Manual Chapter 7: MONITOR, forcoding rules). Only that standard data to which the data given are proportional should be
coded. Other information should be entered under the information-identifier keyword
ASSUMED (see Assumed Values).
Note: Data that are measured as consistency checks should not be coded under MONITOR.
They should, however, be coded as a separate data table if the data are given.
Standard information should be coded except when it is not relevant, as for quantities that areusually obtained without a standard, that is:• total cross sections,• nuclear quantities (see Nuclear Quantities),• ratios,• quantities defined using the modifiers RS, RSL, RSD, REL,
• scattering radius, strength function, average level spacing,• resonance parameters; however, for resonance areas, peak cross sections and similar
quantities, either the standard should be given or a cross-reference to the data from which
the resonance parameters were deduced.
For all other quantities that can be measured either with a standard or absolutely, the positive
statement in free text that the data are measured absolutely is pertinent information and,
therefore, should be included.
However, so-called "absolute" data often depend on the assumption of certain numericalvalues (e.g., for calibrations or corrections); it is desirable to give such values in free text.
The compiler should restrict the use of the term absolute to those cases in which it is known
that there are no "hidden" standards.
For complicated descriptions of standards or normalization procedures, a cross-reference topublished literature may be sufficient.
The reference pertinent to the standard(s) used in coded using the information-identifier
keyword MONIT-REF (see EXFOR Manual Chapter 7: MONIT-REF, for coding rules).
Decay data for the standard(s) used is coded using the information-identifier keyword
DECAY-MON (see EXFOR Manual Chapter 7: DECAY-MON, for coding rules).

S.14

November 2005

LEXFOR

Standards (continued)
Entry of standard values into DATA or COMMON. (See examples on following page).
1. If standard values are given at several points (i.e., energies, angles), these values are givenin the data table as an additional field under the data heading MONIT. See example (1) on
following page.
2. If the data is normalized to a standard at one point (i.e., energy, angle), there are two
possibilities:• the standard is entered as in case (1), above; the data field headed by MONIT is blank for
all but one line.
• the standard is entered in the COMMON section under the data heading MONIT. The
incident energy, secondary energy, angle, etc., at which the normalization was done areentered under the data headings EN-NRM, E-NRM, ANG-NRM, respectively. These areomitted if the data table includes only one data point for which the independent variables
are the same as those for the normalization value. See example (2) on following page.
3. If the originally measured ratio (data/standard) is also given, see example (3) on following
page.
4. If the data are normalized at two or more energies in an unspecified way, this should be
noted in free text in an appropriate place.
Note: Every data line must have a dependent variable entry; therefore, standards may not beentered on a separate line in the data table.
5. If two or more standard reactions are given for the same data set, see EXFOR Manual
Chapter 7: MONITOR, for coding rules.
Numerical values for the uncertainty are entered using the data heading MONIT-ERR.
Further information can be entered under the keyword ERR-ANALYS, see EXFOR Manual
Chapter 7: ERR-ANALYS.
List of commonly accepted neutron reaction standards
1-H-1(N,EL)1-H-1
SIG and DA
1 keV to 20 MeV
2-HE-3(N,P)1-H-3
SIG<50 keV
3-LI-6(N,T)2-HE-4
SIG<100 keV
5-B-10(N,A)3-LI-7
SIG
to gnd, 1st exc.st. <100 keV
6-C-12(N,EL)6-C-12
SIG<2 MeV
25-MN-55(N,G)25-MN-56
SIG
thermal27-CO-59(N,G)27-CO-60
SIG
thermal79-AU-197(N,G)79-AU-198 SIG
thermal, 200 - 3500 keV
92-U-235(N,F)
SIG
100 keV - 20 MeV
98-CF-252(0,F)
NU and DE---

November 2005

S.15

LEXFOR

Standards (continued)
Examples:1.) Use of data heading to link BIB and DATA.
BIBMONITORMONIT-REF
DECAY-MON…
ENDBIBNOCOMMON
DATA
EN
MEV
1.
2.
3.
ENDDATA(MONIT1,…)(MONIT2,…)((MONIT1)…
((MONIT2)…
((MONIT1)…
((MONIT2)…

DATA
B
…
…
…

MONIT1
B…
…
…

MONIT2B…

2.) Normalization information given in COMMONCOMMON
EN-NRM
MEV---ENDCOMMON

E-LVL-NRM
MV
----

MONIT
MB
----

3.) Use of pointers to link BIB and DATA.
BIBREACTIONMONITOR…
ENDBIBNOCOMMON
DATA
EN
MEV
…
ENDDATA

S.16

1 ((3-LI-6(N,T)2-HE-4,,SIG)/(92-U-235(N,F),,SIG)
2 (3-LI-6(N,T)2-HE-4,,SIG)
2 (92-U-235(N,F),,SIG)

DATA
NO-DIM…

1 DATAB…

2 MONITB…

2

November 2005

LEXFOR

StatusVarious types of information are combined under the Information-Identifier Keyword
STATUS. See EXFOR Manual Chapter 7, STATUS, for coding rules and Dictionary 16 for acomplete list of codes and their use. Some general items should be kept in mind:
Preliminary - Superseded - Final Data
If the STATUS codes PRELM and SPSDD are absent, the data are understood to be final.
The frequent case in which a preliminary data set is replaced by its final version can behandled in one of two ways:
1. the final set replaces the preliminary set in the same subentry so that the preliminary set isdeleted from the file.
2. the final set is entered into a new subentry (preferably in the same entry). The earlier set islabeled as superseded with a cross-reference to the data set which supersedes it. If the earlier
set has the status code PRELM, it is removed. (The codes PRELM and SPSDD exclude eachother.)
Example: STATUS(SPSDD,10048009)

The superseding subentry should have a free text cross-reference to the superseded subentry.
This is the preferred method if the earlier data has already been published.
The code SPSDD can also be used when a data set is withdrawn by the author without
replacement. Explanation is required in free text.
Dependent Data - see Dependent Data.
Author Approval
After the proof copy of a data set has been approved by the author, the code APRVD isentered under STATUS. The absence of the code APRVD means that no reply on the proof
copy has been received from the author.
Example: STATUS(APRVD) Approved by J. Doe, 7 January 2004

Source of the data
The actual source from which the numerical values given in the data set were taken may beentered in free text under STATUS.
When the author’s original numerical values have been lost or are not obtainable, data readfrom graphs, if available, should be entered into EXFOR for completeness. Data of this typeshould be labeled with the status code CURVE.
Example: STATUS(CURVE) Scanned from Fig. 1 in reference.

Note: Older entries may have been labeled only under the keyword COMMENT or HISTORY.

November 2005

S.17

LEXFOR

Status (continued)
Normalization
If the codes OUTDT and RNORM are absent, the data are compiled as resulting from theauthor’s corrections and normalizations.
Only in exceptional cases should renormalizations or reassessments of the data as given by anevaluator be compiled. However, some "renormalizations" are not trivial multiplication by afactor; for instance, when a detector-efficiency curve or the geometry of the experiment isinvolved. For such cases, see Corrections.
A data set that is renormalized by an evaluator is labeled with the status code RNORM. The
older data set that is superseded by the later renormalization or reassessment is labeled withthe status code OUTDT. Both must give a cross reference to the other data set as follows:
Examples:STATUSSTATUS(OUTDT,10231002)(RNORM,10231003)

Renormalization, in general, should be done by the compiler only with the advice and/or
consent of the author.
Interdependent Data
Different results for the same quantity obtained in the same experiment by two different
methods of analysis may be coded in the same subentry, see EXFOR Manual Chapter 5.
Such data may also be entered in separate subentries, in which case, the subentries should belinked to each other using STATUS code COREL. (See EXFOR Manual Chapter 7: STATUS,
for coding details).
Example: STATUS(COREL,X0001002)

Unobtainable data
In the case where a center is aware that data exist, but the center is unable to obtain the data,an entry may be made in EXFOR to inform the other centers (and their users) of the status of
the data; this will eliminate many repeated requests for the same data and needless
bookkeeping concerning data which will be entered into the system with extensive delays or
not at all.
The BIB section of the entry should be prepared as usual, containing at least the obligatory
keywords (see EXFOR Manual, page 7.2). The code UNOBT is entered under the keyword
STATUS, followed by free text giving, if known, the approximate date when the data may bereleased, or the reason the data cannot be obtained.
The COMMON section should contain minimum and maximum of the incident-projectile
energy, if known.
At least one data subentry should be included containing, at minimum the reaction; thesystem identifier NODATA replaces the DATA section (see EXFOR Manual Chapter 2).

S.18

November 2005

LEXFOR

Status (continued)
Data translated from older libraries
Data that have been converted from older data libraries are given a status code to indicate thelibrary from which they were converted. Such data may not have all the required BIB
information.

November 2005

S.19

LEXFOR

Sums
Sums of 2 or more reactions can be expressed as a reaction combination using the separator‘+´ (see EXFOR Manual Chapter 6).
Examples:1.) Single target nucleus; sum of reactions
REACTION((28-NI-58(N,N+P)27-CO-57,,SIG)+(28-NI-58(N,D)27-CO-57,,SIG))

2.) More than one target nucleus; more than one reaction
REACTION((28-NI-58(N,P)27-CO-58,,SIG)+(28-NI-60(N,T)27-CO-58,,SIG))

For mathematical correctness, certain reaction combinations require that isotopic abundances
be coded in SF8:
Example: For the production of 58Co from neutrons on a natural nickel sample, where
only the 58Ni(n,p) and 60Ni(n,t) reactions contribute:
REACTION((28-NI-58(N,P)27-CO-58,,SIG,,A)+(28-NI-60(N,T)27-CO-58,,SIG,,A))

Sum reactions such as absorption or nuclide production, where the individual competing
reactions may not be known, are not coded using the form above.
Reactions to sums of isomeric states are coded using the separator "+" in the isomer field of
the reaction product; see Isomeric States.
Example: (…(P,X)39-Y-102-M1+M2)
Note: If the sum of all isomeric reactions is equal to the cross section for the given nuclide, it
is coded without the isomer field.

S.20

November 2005

LEXFOR

Target Nucleus
The target nucleus to be coded is the one to which the data refer; this is not necessarily thesame as the actual material which was irradiated in the experiment. If an isotopic mixture ora chemical compound was used as the experimental target, the data may, nevertheless, begiven for one isotope, and that isotope should be coded.
Codes valid for target nuclei are flagged in column 13 of Dictionary 27 (see Dictionary
Manual).
If a reaction can occur, by energetic reasons, for only one of the isotopes in the irradiatedtarget, that isotope should be coded as the target nucleus. In these cases, if corrections forisotopic abundance have not been or cannot be applied, one of the following modifiers isgiven with the quantity code (see Dictionary 34 for definition of codes):
A
(A)
FCT

- data times isotopic abundance of target, where target is a natural isotopic mixture.
- used as above when it is not clear whether the data were corrected for abundance.
- used for an enriched target, where enrichment «100%. (In this case, a free text
explanation is necessary.)In these cases the target description must be entered under the keyword sample.
The neutron as target nucleus, (e.g., for neutron-neutron interactions) is coded as 0-NN-1.
For elemental targets, see also Elements.
For compounds as targets, see also Compounds.
The isomeric state code -G is never used for a target nucleus. See also, Isomeric States.
For coding rules see EXFOR Manual Chapter 6.

November 2005

T.1

LEXFOR

Tautologies
Tautologies may be used when a data set can be equally well described by two or morereactions which are identical in the energy range considered. If used, the sequence of thereactions should be such that the one with the narrowest definition (as outlined below) is
given first.
Tautologies are expressed as a reaction combination using the separator "=" (see coding
rules EXFOR Manual Chapter 6). Its use is optional, i.e., at the discretion of the compiler.
Examples of tautologies that may be entered:
1. For data below thresholds. For example, total scattering equals elastic scattering below
the inelastic threshold.
2. Emission cross sections, for certain secondary energies)RUH[DPSOHWKH UD\HPLVVLRQFURVVVHFWLRQHTXDOVWKHLQHODVWLF FURVVVHFWLRQIRUVRPH UD\HQHUJLHVBroader definitions, in general, should be used only when two or more competing reactions
are present. This rule seems to avoid any real cases of a tautology. However, where theauthor uses the broader definition to define the reaction, it may be useful to code both for
purposes of identification.
The tautology formalism should not be used in the following cases:
1. When a data set extends beyond a known threshold, the broader definition, and only thebroader definition, should be used. (See also Thresholds).
2. Where a compiler has doubts about which quantity is actually given in a data set, thecompiler must decide in favor of one of the possible codes.
3. In old papers obsolete designations such as "inelastic collision cross section" fornonelastic or "absorption" for (n  PD\ KDYH EHHQ XVHG  ,Q WKHVH FDVHV WKH SUHVHQWO\
valid definition is always used. The author’s designation may be given in free text.

T.2

November 2005

LEXFOR

Thermal Neutron Energies
Thermal energy is defined as 2200 m/sec or 0.0253 eV or 273 K.
Cross sections given for a thermal reactor spectrum must be coded with:
SPA if the spectrum has a non-negligible epithermal part.
MXW if the result has been corrected for the epithermal part of the spectrum, or if theepithermal part is negligible.
In the Westcott formalism [1], which assumes that the thermal part of the spectrum is
Maxwellian, a cross section averaged over a thermal reactor spectrum (effective crosssection) is described as: σˆ = σ 0 ( g + rs)
where

0 = cross section at 2200 m/sec.
g = ratio of Maxwellian to 2200 m/sec cross sectionr = epithermal index: measure of the proportion of epithermal neutrons inthe spectrum (r = 0 for Maxwellian spectrum)s = temperature dependent quantity given by:

s=

where

4T  RI
4 E0  −g
ECd 
π T0  σ 0

RI = resonance integral
ECd = cadmium cutoff energy

If the cross section varies as 1/v, g = 1 RU 0 =MXW.

See also Spectrum Average.
Reference[1.] C. W. Westcott, AECL Chalk River report AECL-1101 (1960).

November 2005

T.3

LEXFOR

Thermal-Neutron Scattering(See also Scattering).
Theory: The scattering of slow neutrons (energies less than 0.1 eV), with matter depends on
the atomic structure of the material (because the wavelength of slow neutrons is of the orderof inter-atomic distances) and on the atomic dynamics in the scattering medium (because theenergy of slow neutrons is of the same order as the chemical bonding energy and the energyof thermal motion of atoms in crystals and solids). At these energies, two types of scatteringmust be considered; nuclear scattering and magnetic scattering due to the interaction between
the magnetic moment of the neutron and the magnetic moment of the electrons of the target.
Coding: For all scattering processes where molecular and crystalline forces are involved thecode THS is used in reaction SF3.
The sample temperature should be given using the data-heading TEMP.
The crystal structure of the sample is given using the information-identifier keyword
SAMPLE.
The following special processes are defined:
1. Free-Atom Scattering. Scattering by a free nucleus, originally at rest.
REACTION coding: FA in SF5 (Branch)
2. Bound-Atom Scattering. Scattering by a nucleus bound in a crystal lattice.
REACTION coding: BA in SF5 (Branch)
3. Coherent Scattering. Collective scattering by a regular arrangement of scattering
centers with common physical properties that will ensure a constant phase relationshipbetween waves scattered by different centers. That is, a single wave is produced with aresultant amplitude due to scattering by a set of particles as a whole.
REACTION coding: COH in SF5 (Branch)
4. Incoherent Scattering. Scattering by a non-regular arrangement of scattering centers,
which will lead to random phase differences by the scattered waves. That is, the incoherent
scattering cross section is the sum of the cross sections for the individual centers.
Isotopic Incoherence: due to a random distribution of different isotopes in the scatteringtarget. If there is only one isotope in the target, there will be no isotopic incoherence.
Spin Incoherence: due to orientation of the neutron and nuclear spins. Spin incoherence may
be eliminated by using polarized neutrons and polarized targets.
REACTION coding: INC in SF5 (Branch)

T.4

November 2005

LEXFOR

Thermal-Neutron Scattering (continued)
Scattering Amplitudedσ2= f (θ )dΩwhere the scattering amplitude (f) is a function of the wavelength of the incident projectile
and of the relative orientation of the incident-projectile spin and target spin.

Definition:

For neutrons, for which only s-wave scattering is possible (and for which the scattering is,therefore, isotropic), and for zero energy: f = -a, where a is the Fermi scattering length.
REACTION Coding: AMP in SF6 (Parameter)
Example:(…(N,THS)…,COH,AMP)

References[1.] I. I. Gurevich and L. V. Tarasov, Low-Energy Neutron Physics (North Holland
Publishing Co., Amsterdam, 1968).
[2.] W. Marshall and S. W. Lovesey, Theory of Thermal Neutron Scattering (Oxford
University Press, London, 1971).

November 2005

T.5

LEXFOR

Thermonuclear Reaction Rate
Reaction Rate
Definition: The thermonuclear reaction rate is defined as cross section times ion velocity
averaged over the Maxwellian-Bolzmann distribution of relative ion velocity distribution of
the temperature kT:∞ν dv∫ (σ ⋅ v )eσ ⋅v =ν dν
∫ e− mv 2 / kT

2

0

∞

− mv 2 / kT

20

The ion with the mass m2 has the velocity v relative to the target ion of mass m1. The
reduced mass m of the ion pair is m = m1 m2/(m1 + m2).
REACTION Coding:(…,SGV,,MXW)

Units: code from Dictionary 25 with the dimension B*V (e.g., CM3/SEC).
Energy Coding: Data are given as function of the Maxwellian temperature (kT), which iscoded under the data heading KT with units of energy. See Spectrum Average for definitionof incident spectrum.
Thermonuclear S-factor, (see Astrophysical S-factor)

References[1.] D. D. Clayton, Principles of Stellar Evolution and Nucleosynthesis (McGraw-Hill,
N.Y., 1968).
[2.] W. A. Fowler, et al, Thermonuclear Reaction Rates, Ann. Rev. Astron. Ap. 5, 525(1967)[3.] T. A. Tombrello, Energy from charged particle reactions among light nuclei, Nuclear
Cross Sections and Technology, Proc. Cong., Washington, D. C., 1975, National
Bureau of Standards Special Publication 425 (1975) p. 659[4.] J. M. Davidson, et al, Low Energy Cross-Sections for B-11(p,3à), Nucl. Phys. A 315,
253 (1979).
[5.] C. A. Barnes, Advances in Nuclear Physics, Vol. 4 (Plenum, New York, 1971) p. 133

T.6

November 2005

LEXFOR

Thick- and Thin-Target Yields
Thick-target yields: yield of an outgoing particle (or radiation) measured on a target whose
thickness is such that the incident beam is either:• completely stopped within the target,• significantly degraded in energy,• degraded in energy to below the threshold for producing the measured product.
Thin-target yields: yield of an outgoing particle (or radiation) measured on a target whose
thickness is such that the incident beam is less significantly degraded in energy, and which is
given as a function of incident beam current. The incident energy range must be given in thedata table under the field headings EN-MIN and EN-MAX, or, if the final energy is not
specified, the incident energy and target thickness must be given under EN and THICKNESS.
The data are sensitive to target thickness and beam profile. The energy loss is a function of
the stopping power (S) of the target material.
The thick target yield is given by−1

 dE ′ 
Ythick ≈ ∫ σ ( E ′) ( E )  dE ′
E2
 dX

S = dE / dX
E0

where

E0 is the incident particle energy,
E2 is the final energy of the incident particle; either 0 if the beam is stopped in
the target, or equal to the energy of the particle exiting the target,
E LVWKHHQHUJ\DWDJLYHQGHSWKLQWKHWDUJHW
X is the target thickness in g cm-2.

Types of data compiled:
1. Saturated thick/thin-target yield: target yield measured after a long irradiation time (i.e.,
longer than 3 half-lives of the product activity) and usually given as decay rate per unit ofincident beam current.
REACTION Coding: TTY in SF6
Units:: a code from Dictionary 25 with dimension TTY (decay rate per unit of beam current),e.g., MCI/MUA.
2. Production1 thick/thin-target yield: (unsaturated) target yield measured after an irradiation
time that is short compared to the product half-life and given as decay rate per unit ofincident beam current ∗ time.
REACTION Coding: TTY,,DT
Units: a code from Dictionary 25 with dimension TTT (decay rate per unit of beam current ∗time), e.g., MCI/MUAHR or DPS/MUAHR.

1

Do not confuse with product yields.

November 2005

T.7

LEXFOR

Thick- and Thin-Target Yields (continued)
3. Physical thick/thin-target yield: target yield measured after an irradiation time that is shortcompared to the product half-life, is given as decay rate per unit of incident beam current ∗time, and has been corrected for decays during irradiation.
REACTION Coding: TTY,,PHY
Units: a code from Dictionary 25 with dimension TTT (decay rate per unit of beam current ∗time), e.g., MCI/MUAHR or DPS/MUAHR.
4. Other representations of thick target yieldsa) Thick Target Product Yields: thick target yield of a reaction product, where the value
is given in units of number of nuclei as a function of incident beam current.
REACTION Coding: TTY/PY in SF 6.
Units: a code from Dictionary 25 with dimension PYT, e.g., PRD/MUAHRb) Thick Target Yield Multiplicities: yield of an outgoing particle (or radiation), wherethe value is given as the number of particles as a function of incident beam current.
REACTION Coding: TTY/MLT in SF 6.
Units: a code from Dictionary 25 with dimension PYT, e.g., PRT/MUAHR
c)

Production thick target yield per 1 MeV of target thickness.

REACTION Coding: TTY,,TM in SF 6.
Units: a code from Dictionary 25 with dimension TTTE, e.g., CI/AHR/MEV
5. Data measured on a thick target and not corrected for target thickness (use General
Quantity Modifier TT in REACTION SF8).
a)Thick Target Cross Sections: cross section measured on a thick target.

REACTION Coding: SIG in SF 6; modifier TT in SF8.
Units: a code from Dictionary 25 with dimension B, e.g., MBb) Thick Target Product Yields: thick target yield of a reaction product, where the value
is given in units of number of nuclei per incident projectile.
REACTION Coding: PY in SF 6; modifier TT in SF8.
Units: a code from Dictionary 25 with dimension YLD, e.g., PRD/INCc) Thick Target Yield Multiplicities: yield of an outgoing particle (or radiation), wherethe value is given as the number of particles per incident projectile.
REACTION Coding: MLT in SF 6, TT in SF8.
Units: a code from Dictionary 25 with dimension YLD, e.g., PRT/INCd) Thick Target Gamma-Ray Yields: gamma spectrum, where the value is given as thenumber of particles per incident projectile as a function of gamma energy.
REACTION Coding: SPC in SF 6, TT in SF8.
Units: a code from Dictionary 25 with dimension YLD, e.g., PRT/INC

T.8

November 2005

LEXFOR

Thick- and Thin-Target Yields (continued)
Similarly, all quantities may be given as angular distributions, excitation functions, etc. See
Table following and Dictionary 36 for a complete list of quantities.
Unit definitions
Saturated thick target yields are most often measured as observed decay rate per unit of beam
current. Unsaturated thick target yields are most often measured as observed decay rate perunit of beam current per unit time.
Measures of beam current
Ampere:SI fundamental unit of current.
Coulomb:
SI fundamental unit of charge; 1 C = 1 Ampere of current for 1 second.
Measures of decay rate
Becquerels SI fundamental unit of radioactivity; 1 Bq = 1 decay/second.
Curies2:
unit of radioactivity; 1 Ci = 3.7x1010 decays/second.
1 Bq = 2.7x10-11 Ci

Table of data types verses unit types
Unit type forType of data compiled
Saturated thick/thin-target yield
Production thick/thin-target yield andPhysical thick/thin-target yieldThick target cross section
Cross section
Thick target product yield
Fn. of beam current
and multiplicity
Thick target product and# of nuclei/inc.
gamma yield,
multiplicity
Production thick target yield per 1 MeV of target
thickness.

2

type

d/d

d/dE

TTY

TDA

TDE

d2/d /d
E
TD2

TTT

TTDA

TTTE

TTD2

B

DA

DE

DAE

PYT

PYTA

PYTE

PYT2

YLD

1/A

1/E

1/AE

TTT
E

The Curie has been replaced in usage by the Becquerel.

November 2005

T.9

LEXFOR

ThresholdA data set may extend beyond a threshold. For example, a data table resulting from aneutron-detecting experiment may actually give in a single data set:
1. elastic scattering below the inelastic threshold energy, and total scattering above theinelastic threshold energy;
2. total scattering below the (n,2n) threshold energy, and neutron production above the (n,2n)
threshold energy.
In these cases the wider definition should be used, that is: in the first case, the table should beentered as total scattering; in the second case, as neutron production.
The compiler must not split the data set in two parts below and above the threshold.
When retrieving, for example, elastic scattering data, one should realize that it may also be
worthwhile to retrieve total scattering, with energy below the threshold energy.
If, however, as in (1.), above, the data table has been corrected for inelastic neutrons, or if the
portion of inelastic neutrons measured is negligible, the data set may be given as elastic
scattering.
See also Tautologies.

T.10

November 2005

LEXFOR

Title
Full title of work, document or experiment is given in free text. If the original title is not inEnglish, only a literal English translation is given. Computer-compatible substitutes should
be used where necessary (e.g.DOSKDIRUWKH*UHHNOHWWHU 
Where no title is given, e.g., private communications, a title that describes the experiment
may be provided by the compiler.
See EXFOR Manual Chapter 7: TITLE for coding rules.

November 2005

T.11

LEXFOR

Total
Total cross section
Definition: the sum of all energetically possible interactions.
REACTION Coding: TOT in SF3
Examples: (…(N,TOT),,SIG)(…(N,TOT),,WID)
Sum-rules: Total= elastic plus nonelastic= scattering plus absorption.

Note: At thermal energies, where a large portion of the total cross section may be due tocrystal effects (thermal scattering), the sample structure should be given using the
keyword sample, if provided by the author.
Transmission: “Raw” data measurement of the total cross section.

1e − nσ T = 1 − n σ T + n 2 σ T22
where <…> denotes resolution broadening
n is the sample thickness in nuclei/barn
T is the Doppler-broadened, abundance-weighted total cross sections.
REACTION Coding: TRN in SF6
Example: (…(N,TOT),,TRN)
Note: Older transmission data entries may be compiled with the code RAW in SF6.
Self Indication: see Self Indication.

Total reaction cross section: This is defined as all reactions except elastic scattering.
Equivalent to Nonelastic, coded with SF3 = NON. See also Nonelastic.

Total as distinct from partial: no code is given under REACTION for "total", except when
it refers to the total cross section, see above. Instead, codes are given in the branch field for"partial" reactions.
Examples:(N,F),,NU= total(N,F),PR,NU= prompt(N,INL),,SIG= total inelastic scattering cross section(N,INL),PAR,SIG = partial inelastic scattering cross section.

T.12

November 2005

LEXFORUnits
A datum or value is always a combination of a number and a unit. For example, 500 mb and.5 b is the same value; mb and b are units of the same dimension (or units group). Units ofthe same dimension can be converted into each other by multiplication with a numerical(dimensionless) factor.
For example, Angstrom and cm are units of the same dimension.
A quantity can have only one dimension, i.e.,• a quantity (reaction code) can be combined with only one group of units,• or, data with different dimensions cannot have the same quantity code.
In general, in order to avoid errors in conversion, data are coded in the units given by theauthor. However, every effort should be made to compile the data in existing codes, since theproliferation of non-standard unit codes is not desirable. For exotic unit codes, the compiler
may choose to convert the data to standard units. This should be accompanied by a commentin the BIB section giving the relationship used for the conversion. The original data should
also be entered using the data heading MISC-COL and the units SEE TEXT.
Unit Dimension Codes
In Dictionary 36 (REACTION), each quantity code given is followed by a code indicating thedimension of the quantity. For example, E means energy units (milli-eV, eV, keV, MeV,etc.), NO means dimensionless (i.e., unit "one").
The same dimension codes are also given in Dictionary 25 (Units), so that it is possible tocheck by computer whether a given quantity code is combined with a unit code which has thecorrect dimension. For example, the reaction quantity code SIG has the dimension B and can
only be given in units B, MB, etc., which also have the dimension code B.
Unit Conversion Factors
In Dictionary 25, a conversion factor is given for each unit code, which allows computerized
conversion between different units of the same dimension.
Special cases (See also EXFOR Manual Chapter 4).
1. An angle given in degrees and minutes must be entered in two separate fields with the data
heading ANG repeated.
Example:
ANG
ADEG
90.

ANG
AMIN
47.

ANG
ASEC
10.

2. If data are given in arbitrary units (ARB-UNITS), the quantity code is marked as"relative" by entering the modifier REL in reaction SF8. See Relative.

November 2005

U.1

LEXFOR

Units (continued)
3. Errors must have the same dimension (not necessarily the same units) as the quantity towhich they refer, or must be in percent.
4. The unit PER-CENT is used only for errors or resolutions and must not be used under thedata-heading keyword DATA. If data were given using PER-CENT, the meaning of PERCENT in the error field would be ambiguous. Data given by the author in percent should be
converted to NO-DIM by dividing the results by 100. If the data error is given in percent, thisalways means a percentage of the relevant data.
5. The unit SEE TEXT may be used in a MISC data field when no code from Dictionary 25
applies. It is explained in free text under MISC-COL. It must not be used with any other data
heading. (See Miscellaneous).

Note: The compiler should avoid any carelessness in the use of units. This would jeopardize
any automatic data processing. It is forbidden to set the light velocity c = 1 or Planck’s
constant h = 1 as is usually done in high-energy physics.

U.2

October 2004

INDEXLEXFOR

Absorption.................................................................................................................... A.1
Abundance of decay radiation .................................................................. See Decay Data
Abundance, isotopic ............................................................................................ T.1, S.20
Activation ..................................................................................................................... A.2
Adler-Adler parameters................................................................................................ M.5
Alloys ............................................................................................................................ C.2
Alpha ............................................................................................................................. A.1
Analysis ........................................................................................................................ A.3
Analyzing power ..........................................................................................................P.11
in spherical coordinates ...........................................................................................P.14
tensor ............................................................................................................. P.11, P.14
vector ............................................................................................................. P.11, P.14
Angle ............................................................................................................................ A.4
error/resolution ......................................................................................................... A.4
given in degrees, minutes, seconds........................................................................... U.1of secondary particle................................................................................................. A.4
two or more............................................................................................................... A.4
Angle/energy correlations ........................................................................................... D.13
Angle/energy distributions .......................................................................................... D.12
Angular correlation ..................................................................................................... D.10
Angular distributions..................................................................................................... D.9
azimuthal ................................................................................................................ D.11
non-coplanar ........................................................................................................... D.11
Treiman-Yang......................................................................................................... D.14
Arbitrary units ............................................................................................................... U.1
Assumed values............................................................................................................ A.5
Astrophysical S- factor................................................................................................ A.6
Asymmetry ...................................................................................................................P.10
fission ........................................................................................................................F.2
Author .......................................................................................................................... A.7
Author approval............................................................................................................S.17
Average data.................................................................................................................. G.2
Average kinetic energy...................................................................................................S.6
of fission neutrons .....................................................................................................F.4
Average level spacing ................................................................................................... A.8
Average number of neutrons per fission ....................................................................... N.1
Average resonance parameters .................................................................................. A.8
Basel convention ............................................................................................................P.8
Binary fission ...................................................................................................See Fission
Bound atom scattering................................................................................................... T.4
Capture .......................................................................................................................... A.1
Center-of-Mass System ............................................................................................... C.1
Chain yield .....................................................................................................................F.9
Charge-changing cross section...................................................................................... C.8
Charge yields................................................................................................................F.10
Chemical Compounds ................................................................................................. C.2
Coherent scattering........................................................................................................ T.4
Coincident measurements ............................................................................................ M.1
Index-1

LEXFOR

Comments .................................................................................................................... C.3
flag... ......................................................................................................................... C.3
Compilation responsibility - determining .......................................................................I.5
Compound nucleus interaction...................................................................................... R.4
Compounds............................................................................... See Chemical Compounds
Continuum gammas........................................................................................................P.2
Conversion factors for units .......................................................................................... U.1
Corrections................................................................................................................... C.4
Correlated data .............................................................................................................S.18
Correlated particle pairs
angular distribution................................................................................................. D.10
fission yields ............................................................................................................F.11
Correlations
angular... ............................................................................................................. ....D 10
secondary energy .................................................................................................... D.12
secondary linear momentum................................................................................... D.12
Cosine coefficients .......................................................................................................F.12
Cosine-squared coefficients .........................................................................................F.15
Coulomb scattering ........................................................................................................S.3
Covariance ................................................................................................................... C.5
Critique.......................................................................................................................... C.3
Cross sections............................................................................................................... C.7
at resonance peak.................................................................................................... R.10
emission...................................................................................................................P.16
fission spectrum averaged .........................................................................................F.5
high and low energy components ............................................................................. R.5
integral over incident energy .................................................................................... C.7
production................................................................................................................P.16
spin-spin ................................................................................................................... C.8
total ......................................................................................................................... T.12
total charge-changing ............................................................................................... C.8
Cumulative data...............................................................................................................I.3
Cumulative yieldfission product ...........................................................................................................F.8
Data
average...................................................................................................................... G.2
error .......................................................................................................................... E.3
miscellaneous................................................................................................... G.2, M.2
raw ............................................................................................................................ G.2
relative ...................................................................................................................... G.2
times a factor ............................................................................................................ G.2
times natural isotopic abundance.............................................................................. G.2
Data heading
FLAG.......................................................................................................................F.16
LVL- FLA G............................................................................................................F.17
DECAY-DATA .......................................................................................................F.16
Data source...................................................................................................................S.17

Index-2

LEXFOR

Data Type ..................................................................................................................... D.1
Decay Data ................................................................................................................... D.2
errors...................................................................................................................... ...D.3
flags .........................................................................................................................F.16
for standard ............................................................................................................... D.2
half life...................................................................................................................... H.1
variable product nucleus........................................................................................... D.3
Decay energy............................................................................................... See decay data
Delayed Fission Neutrons ........................................................................................... D.4
groups ....................................................................................................................... D.4
Dependent Data ........................................................................................................... D.7
Dependent Variable..................................................................................................... D.8
Derived data .................................................................................................................. D.1
Detector ........................................................................................................................ M.1
Differential Data.......................................................................................................... D.9
Digitizing errors ............................................................................................................ E.4
Dipoles ........................................................................................................................ M.l0
Direct interaction........................................................................................................... R.4
Disappearance cross section.......................................................................................... A.1
Discrete gammas
vs. continuum ............................................................................................................P.2
Dosimetry Neutron Reaction Data........................................................................... D.16
Elastic scattering ............................................................................................................S.2
Elements. ...................................................................................................................... E.1
Emission cross section .................................................................................................P.16
Emission probability
delayed-neutrons....................................................................................................... D.6
Energyerror .......................................................................................................................... E.3
incident projectile.. .....................................................................................................I.2of resonance................................................................................ See Resonance energy
secondary particle ......................................................................................................S.5
spectrum average .....................................................................................................S.12
thermal ...................................................................................................................... T.3
Energy distributions .................................................................................................... D.12
Energy spectrum
delayed neutrons ....................................................................................................... D.5
fission neutron ...........................................................................................................F.4
Energy step
used in analysis......................................................................................................... A.3
Epithermal spectrum average .......................................................................................S.12
Errors ........................................................................................................................... E.2
correlations ............................................................................................................... E.4
covariance................................................................................................................. C.5
digitizing................................................................................................................... E.4
Eta.................................................................................................................................. N.1
Facility of measurement ............................................................................................... M.1

Index-3

LEXFOR

Fermi-gas model parameters ......................................................................................... N.3
Fission............................................................................................................................F.1
asymmetry .................................................................................................................F.2
ternary........................................................................................................................F.2
Fission fragments
bulk ............................................................................................................................F.1
Fission neutrons
delayed...................................................................................................................... D.4
Fission-Neutron Spectra ..............................................................................................F.3
Fission Yields ................................................................................................................F.6
fractional....................................................................................................................F.9
Fitting Coefficients .....................................................................................................F.12
Flags.............................................................................................................................F.16
decay......................................................................................................................... D.3
level .........................................................................................................................F.17
Fractional yields .............................................................................................................F.9
Free atom scattering ...................................................................................................... T.4
Free Text .....................................................................................................................F.18
Fusion ............................................................................................................................ R.6
Gamma rays
continuum region.......................................................................................................P.2
intensities ............................................................................................................... ...G.1
Gamma Spectra ........................................................................................................ ...G.1
thick target ................................................................................................................ T.8
General Quantity Modifiers ....................................................................................... G.2
Half lives....................................................................................................................... H.1
See also decay data
History .......................................................................................................................... H.2
Incident Beam Source ...................................................................................................I.1
polarization ..............................................................................................................P.15
Incident-Projectile Energy ...........................................................................................I.2
resolution ................................................................................................................. R.l0
spectrum average .....................................................................................................S.12
Incoherent scattering ..................................................................................................... T.4
Independent and Cumulative Data..............................................................................I.3
Independent Variables..................................................................................................I.4
Independent yieldfission-product ...........................................................................................................F.8
Inelastic scattering..........................................................................................................S.2
Information-Identifier keyword
COMMENT.............................................................................................................. C.3
CORRECTION......................................................................................................... C.4
CRITIQUE................................................................................................................ C.3
DECAY-DATA ........................................................................................................ D.2
EN-SEC .....................................................................................................................S.6
ERR-ANALYS......................................................................................................... E.2
FLAG........................................................................................................................ C.3

Index-4

LEXFOR

Information-Identifier keyword
HISTORY................................................................................................................. H.2
INC-SOURCE ............................................................................................................I.1
MISC-COL .............................................................................................................. M.2
MONIT-REF ............................................................................................................ R.9
REFERENCE ........................................................................................................... R.8
Institute ..........................................................................................................................I.5
Integral cross section..................................................................................................... C.7
Interdependent data ..............................................................................See Correlated data
Isobaric Analog Resonances.........................................................................................I.6
Isomeric ratios ............................................................................................................... R.1
Isomeric States...............................................................................................................I.7
Isotopic abundance............................................................................................... T.1, S.20
Kinematic locus of 2 secondary energies .......................................................................S.5
Kinetic energy of fission fragments
correlated fragment pairs .........................................................................................F.11
distribution.................................................................................................................F.4
Legendre polynomials coefficients ..............................................................................F.14
of the first kind ........................................................................................................F.15
Level properties............................................................................................................. Q.2
Level spacing.............................................................................See Average level spacing
Level-density parameter................................................................................................ N.3
Light-Nuclei Reactions.................................................................................................L.1
Linear momentum
angular distributions ............................................................................................... D.14
distributions ............................................................................................................ D.12
secondary particles ....................................................................................................S.6
Madison convention
spin-1/2 particles........................................................................................................P.9
spin-1 particles.........................................................................................................P.14
Madland-Nix spectrum...................................................................................................F.3
Mass yield ......................................................................................................................F.9
Maxwellian spectrum ...................................................................................................S.12
Measurement Techniques.......................................................................................... M.1
Metastable states .............................................................................................................I.7
partial feeding from ....................................................................................................I.3
quasi............................................................................................................................I.8
Method ......................................................................................................................... M.1
Miscellaneous Data .................................................................................................... M.2
modifier .................................................................................................................... G.2
Monitor..........................................................................................................See Standards
Monoisotopic elements ................................................................................................. E.1
Monopoles.................................................................................................................. M.10
Most probable charge ...................................................................................................F.10
Most probable kinetic energy.........................................................................................S.6
Most probable mass......................................................................................................F.10
Mott scattering................................................................................................................S.4
ratio to..................................................................................................................... D.10
Index-5

LEXFOR

Multilevel Resonance Parameters............................................................................. M.3
Multiple Reaction Formalism ................................................................................... M.7
Multiplicity.................................................................................................................. M.9
thick target ................................................................................................................ T.8
Multipolarity............................................................................................................. M.10
Neutron Yield............................................................................................................... N.1
Nonelastic ..................................................................................................................... N.2
Normalization................................................................................................See Standards
Nu-bar............................................................................................................................ N.1
Nuclear Quantities....................................................................................................... N.3
energy .........................................................................................................................I.2
Nuclear temperature ...................................................................................................... N.3
Octupoles.................................................................................................................... M.10
Out-of-date data............................................................................................................S.18
Partial Reactions ..........................................................................................................P.1
Particle pairs ...................................................................................................................P.5
Particles .........................................................................................................................P.3
considered..................................................................................................................P.4
correlated pairs .......................................................................................... ...C.13, D.10
detected......................................................................................................................P.4
sequence.....................................................................................................................P.3
Photon sources.................................................................................................................I.1
Pointers..........................................................................................................................P.7
Polarity .................................................................................................................... ...M.10
Polarization ...................................................................................................................P.8
in Cartesian coordinates.......................................................................................... M.l0
in spherical coordinates ...........................................................................................P.14
Polarized beam .............................................................................................................P.15
Polarized target.............................................................................................................P.15
Potential scattering .........................................................................................................S.4
Preliminary data ...........................................................................................................S.17
Primary fragment yield...................................................................................................F.7
Product yields ................................................................................................................ R.7
thick target ................................................................................................................ T.8
Production and Emission Cross Sections .................................................................P.16
unweighted...............................................................................................................P.17
Products.......................................................................................................................P.18
algebraic...................................................................................................................P.18
of two or more reactions.........................................................................................P.18
Quadrupoles ............................................................................................................... M.10
Quantum Numbers...................................................................................................... Q.1
for resonances ........................................................................................................... Q.1of excited states ........................................................................................................ Q.2
Quasi-metastable states ................................................................................................. T.8
Radiation detected ..........................................................................................................P.4
Radiation widths.............................................................................. See Resonance widths

Index-6

LEXFOR

Ratios ............................................................................................................................ R.1
implicit in quantity codes ......................................................................................... R.1
isomeric ................................................................................................................. ...R.1
of reactions with different independent variables..................................................... N.1
to Maxwellian distribution ......................................................................................S.13
Raw Data...................................................................................................................... R.2
modifier .................................................................................................................... G.2
Reaction cross section (total) ...................................................................................... T.12
Reaction Mechanisms ................................................................................................. R.4
Reaction plane ............................................................................................................... D.9
Reaction Product ......................................................................................................... R.7
Reaction rate.................................................................................................................. T.6
Reactionsmultiple reaction formalism..................................................................................... M.7
partial .........................................................................................................................P.1
particle sequence........................................................................................................P.3
thresholds.................................................................................................................P.10
Reduced widths ......................................................................... see Resonance parameters
Reference...................................................................................................................... R.8
conferences ............................................................................................................... R.9
monitor ..................................................................................................................... R.9
private communications............................................................................................ R.9
related ....................................................................................................................... R.9
Reich-Moore parameters .............................................................................................. M.3
Relative data.................................................................................................................. G.2
Removal cross section....................................................................................................A.l
Renormalized data........................................................................................................S.18
Resolution.................................................................................................................... R.l0
angular ...................................................................................................................... A.4
incident projectile ................................................................................................... .R.l0
secondary particle ......................................................................................................S.5
Resonance energy
multilevel analysis ................................................................................................... M.3
single-level analysis...................................................................................................S.8
Resonance Integral .................................................................................................... R.11
calculated from resonance parameters.................................................................... R.11
effective energy ...................................................................................................... R.11
infinitely dilute ....................................................................................................... R.11
over smaller energy range....................................................................................... R.11
reduced.................................................................................................................... R.11
Resonance parameters
Adler- Adler............................................................................................................. M.5
average...................................................................................................................... A.8
multilevel ................................................................................................................. M.3
partial radiation widths... ......................................................................................... .G.1
reduced widths...........................................................................................................S.9
Reich-Moore............................................................................................................ M.3
R–matrix .................................................................................................................. M.6

Index-7

LEXFOR

Resonance parameters
single-level.................................................................................................................S.8
Vogt ......................................................................................................................... M.3
Resonance strength.......................................................................................................S.11
Resonance widths ...........................................................................................................S.9
average...................................................................................................................... A.8
partial radiation......................................................................................................... G.1
Rutherford scattering......................................................................................................S.3
ratio to..................................................................................................................... D.10
R−matrix parameters .................................................................................................... M.6
R−values.......................................................................................................................F.10
Sample ...........................................................................................................................S.1
temperature ................................................................................................................S.1
thickness ....................................................................................................................S.1
Scattering ......................................................................................................................S.2
amplitude .................................................................................................................. T.5
bound atom ... ........................................................................................................... T.4
coherent .....................................................................................................................P.4
deep inelastic. ........................................................................................................... R.6
free atom ................................................................................................................... T.4
incoherent ................................................................................................................. T.4of thermal neutrons................................................................................................... T.4
Secondary fragment yield...............................................................................................F.8
Secondary Particles .....................................................................................................S.5
energy ........................................................................................................................S.5
linear momentum.......................................................................................................S.6
Self Indication...............................................................................................................S.7
S−factor
astrophysical ............................................................................................................. A.6
Sine-squared coefficients .............................................................................................F.15
Single-Level Resonance Parameters...........................................................................S.8
Spallation....................................................................................................................... R.5
Spectrafission neutron ...........................................................................................................F.3
gamma ...................................................................................................................... G.1
unresolved gammas .................................................................................................. G.1
Spectrum Average ......................................................................................................S.12
Spectrum temperature ................................................................................................... R.9
Spin-correlation parameter...........................................................................................P.11
Spin-cut-off factor ......................................................................................................... N.3
Spin-depolarization parameter .....................................................................................P.12
Spin-flip
parameter .................................................................................................................P.13
probability................................................................................................................P.13
Spin-rotation
function....................................................................................................................P.13
parameter .................................................................................................................P.12

Index-8

LEXFOR

Spin-spin cross sections ................................................................................................ C.8
Spin-transfer parameter ................................................................................................P.13
Spontaneous fission........................................................................................................F.1
Standards ....................................................................................................................S.14
decay data ................................................................................................................. D.2
reference ................................................................................................................... R.9
Statistical weight factor................................................................................................. Q.1
Status ...........................................................................................................................S.17
Strength functions ......................................................................................................... A.8
Sums.............................................................................................................................S.20
of 2 or more reactions..............................................................................................S.20
of data to more than one isomeric state ...................................................................S.20
Superheavy elements..................................................................................................... E.1
Superseded data............................................................................................................S.17
Target Nucleus............................................................................................................. T.1
polarized ..................................................................................................................P.15
Tautologies ................................................................................................................... T.2
Temperature
nuclear ...................................................................................................................... N.3
sample........................................................................................................................S.1
spectrum...................................................................................................................S.12
Ternary fission................................................................................................................F.2
Thermal Neutron Energies......................................................................................... T.3
Thermal Neutron Scattering ...................................................................................... T.4
Thermonuclear Reaction Rate ................................................................................... T.6
S- factor .................................................................................................................... A.6
Thick and Thin Target Yields .................................................................................... T.7
Threshold ................................................................................................................... T.10
Title............................................................................................................................. T.11
Total............................................................................................................................ T.12
Total charge-changing cross section ............................................................................. C.8
Total cross section....................................................................................................... T.12
self-indication ............................................................................................................S.7
Total reaction cross section ......................................................................................... T.12
Total scattering...............................................................................................................S.2
Translated data (from other data libraries) ...................................................................S.19
Transmission ............................................................................................................... T.12
Treiman- Yang angular distribution............................................................................ D.14
Uncertainties....................................................................................................... See Errors
Undefined reaction channels ..........................................................................................P.5
Units.............................................................................................................................. U.1
for data given in percent ........................................................................................... U.2
miscellaneous............................................................................................................ U.2
SEE TEXT................................................................................................................ U.2
Unobtainable data.........................................................................................................S.18
Variable nucleus formalism
isomeric states........................................................................................................... H.7

Index-9

LEXFOR

Variable number of emitted nucleons ............................................................................P.5
Variables
dependent.................................................................................................................. D.9
independent.................................................................................................................I.4
Vogt parameters ........................................................................................................... M.3
Watt spectrum ................................................................................................................F.3
Wave length.....................................................................................................................I.2
Yieldsneutron ...................................................................................................................... N.1
product ...................................................................................................................... R.7
reaction ..................................................................................................................... R.2
thin and thick target .................................................................................................. T.7

Index-10

Nuclear Data Section
International Atomic Energy Agency
P.O. Box 100
A-1400 Vienna
Austriae-mail: services@iaeand.iaea.org
fax: (43-1) 26007
telephone: (43-1) 2600-21710