Nuclear Data Section
International Atomic Energy Agency
P.O.Box 100, A-1400 Vienna, Austria
Memo CP-D/647
Date:
To:
From:
Subject:

10 June 2010
Distribution
N. Otsuka, V. McLane, O. Schwerer, S. Dunaeva
1. Reaction Coding SF3-SF4
2. Proposed renaming of LEXFOR Secondary Particles
3. Proposed revision and renaming of LEXFOR Particles

Reference:

Memo CP-D/607, 622, 644

1. Proposed revision of the EXFOR Formats Manual Chapter 6. Reaction
Specification
Following is update of the EXFOR Formats Manual section on Reaction SF3 and SF4
and to two LEXFOR entries Particles and Secondary Particles. The entry has beenrearranged for clarity, for example notes have been moved to the appropriate section.
Other than that, the main changes are:• Deletion of the explanation about the branch code (DEF);• Addition of explanation for unstable product nuclei (e.g., 4-BE-8) in SF4;
• Clarification of SF4 coding rule when a process code is coded in SF3.

2. Proposed renaming of LEXFOR Secondary Particles.
We propose to rename this entry to Secondary Energy.

3. Proposed revision of LEXFOR Particles (to be renamed to Outgoing Particles).
Also following is the proposed write-up for LEXFOR Outgoing Particles, which has
been moved from LEXFOR Particles. The explanation of the use of the code (DEF)
has been removed.
(Note that description about incident particles will be moved to another LEXFOR
entry “Incident Particles”. See Memo CP-D/622.)

EXFOR Manual Chapter 6: Reaction field (proposed update for SF3 and SF4)

SF3. Process. In general, this field contains a process code or the particle(s) producedin the reaction with the exception of the reaction product (which is given in SF4), or a
combination of the two (see Coding rules, following).
Coding: This subfield contains one of the following:a) A process code from Dictionary 30, e.g., TOT.
For coding of SF3 in the case of scattering see LEXFOR, Scattering.
b) A particle code from Dictionary 33 with an “allowed SF3 flag” (3) of 2, which
may be preceded by a multiplicity factor with a value of 2→99. 1
Examples:A
4A

Gammas are coded only:• for a capture process, e.g., (P,G).
• when they are needed to define the partial reaction considered, e.g.,(N,G+F),SEQ.
In all other cases, gammas are considered as self-evident and are, therefore,
not coded, e.g., (P,N) is coded, not (P,G+N). Compare SF7, Particle
Considered, page 6.5.
(Explanation of (DEF) removed.)c) For particles heavier than α, a nuclide code in the form Z-S-A-X (see page 6.2, but
the mass number may not have the value zero). No multiplicity factor is allowed;
instead the nuclide code is repeated, if necessary.
Examples:8-O-168-O-16+8-O-16d) Combinations of a), b) and c), with the codes connected by ‘+’. Outgoingparticles are ordered starting with the lightest 2 at the left of the subfield, followedby the Z-S-A-X formatted codes, in Z, A order, followed by process codes given in
the same order as given in Dictionary 30.
An exception to this order is when SF5 contains the code SEQ, which indicates thatthe particles and/or processes are ordered in the sequence in which the reaction
proceeds (see LEXFOR, Outgoing Particles).
Examples:1

HE3+8-0-16
X+N

In the few cases where the multiplicity factor may exceed 99, the Variable Number of EmittedNucleons Formalism may be used, see page 6.9.
2
Lowest Z, then lowest A.

SF4. Reaction Product. In general, the heaviest of the products is defined as thereaction product (also called residual nucleus). In the case of two reaction productswith equal mass, the one with the larger Z is considered as the heavier product.
Exceptions or special cases are:a) If the branch code SEQ is given in SF5, indicating that the sequence of several
outgoing particles and/or processes coded in SF3 is meaningful, the nuclide to becoded in SF4 is the heaviest product of the last process (e.g., break-up).
Examples:(.…(…,D+N)2-HE-4,SEQ,…) Emission of deuteron followed by break-up ofEmission of deuteron followed by unspecified(.…(…,D+X),SEQ,…)(.…(…,D+F),SEQ,…)

5He

process
Emission of deuteron followed by fission.

The branch code SEQ may not be used when there are only two products in SF3and SF4.
b) For a product nuclide that is unstable and breaks up with the emission of a particle(e.g., 8Be → 2α), if the reaction is dependent on the nuclide before break-up, thepre-breakup particle may be coded in SF4. See LEXFOR Light-Nuclei
Reactions (Z<6) for a complete discussion.
c) There is no reaction product if a nuclear quantity is given (i.e., SF2 contains thecode 0).
d) There is no reaction product if the reaction specifies a resonance parameter(defined in Dictionary 236 by using the resonance flag ‘.’).
e) There is no reaction product if the reaction is measured for a target of natural
isotopic composition, excluding scattering.
Examples: (40-ZR-0(N,G),,SIG)
f) If a process code is required for SF3, then there are special rules for what is given
in SF4.
1. For total (TOT), absorption (ABS), nonelastic (NON), and total charge change(TCC) cross sections, SF4 is blank. See LEXFOR, Total, Absorption,
Nonelastic, Reaction Mechanisms, and Cross Sections, respectively, formore information.
2. For fission (F) and fusion (FUS), SF4 is blank or contains nuclide code, avariable product (ELEM, MASS, ELEM/MASS) or variable number of particles(NPART).
3. For the scattering processes, total scattering (SCT), elastic scattering (EL),inelastic scattering (INL), and thermal scattering (THS), the nuclide code in SF1
is also coded in SF4 except for the isomer code, which can be different for(de-)excitation of the isomeric state (see LEXFOR, Scattering).
4. Likewise for pair production (PAI), the nuclide code in SF1 is also coded inSF4.

5. For production quantities where SF3 contains only the code X, SF4 gives theparticle/nuclide considered:• either a nuclide code or a variable product (ELEM, MASS, ELEM/MASS),• or a variable number of particles (NPART).
See LEXFOR, Production and Emission Cross Sections.
Coding: This subfield:a.) either is blank, the following comma is always present.
Examples: (26-FE-56(N,EL),,WID)(92-U-235(N,F),,SIG)(40-ZR-0(N,G),,SIG)b.) or contains a code in the form Z-S-A-X, as described on page エラー! ブックマークが定義されていません。.
If light particles or gammas are defined as the reaction product, these are codedusing the Z-S-A formalism (i.e., the particle codes N, G, P, etc., are not used in SF4).
Examples: (82-PB-0(P,X)0-NN-1,,DA/DE) double differential neutron production
cross section(28-NI-0(N,X)0-G-0,,SIG) γ production cross section
For scattering on a target nucleus which is a natural isotopic mixture (A=0) (seeLEXFOR, Scattering), A=0 is given for the product nucleus; otherwise, A=0 is
not used in SF4.
In the case of isomeric ratios and sums, the isomer code may consist of a
combination of codes separated by a slash or a plus sign. The use of theseseparators is algebraic, without parenthesis, e.g., M1+M2/G. The code T is used in
an isomeric ratio to denote the sum over all isomers (see page エラー! ブックマークが定義されていません。). (See LEXFOR, Isomeric States).
Examples: (92-U-235(N,F)54-XE-124,CUM,FY)(51-SB-123(N,G)51-SB-124-M1+M2/T,,SIG/RAT)c.) or, if the reaction product is entered into the data table using the data headings
ELEMENT, MASS, and/or ISOMER (see page エラー! ブックマークが定義されていません。, Variable Nucleus), it contains one of the following codes:
ELEM if only the data heading ELEMENT is used in the data table,
MASS if only the data heading MASS is used in the data table,
ELEM/MASS
if the data headings ELEMENT and MASS are used in the datatable.
Example: (92-U-235(N,F)ELEM/MASS,CUM,FY)
Use of this formalism is restricted to those cases given on page エラー! ブックマークが定義されていません。.
d.) or, if the number of particles emitted is entered into the data table using the data
heading PART-OUT, it contains the code NPART.

Example: (79-AU-197(92-U-238,X)NPART,NUM,SIG,HF) Cross section for agiven number on heavy fragments emitted; the numberof fragments is given in the DATA or COMMON
section under the heading PART-OUT.
Note on SF3 and SF4
For reaction codes allowed in the coding of neutron-induced reactions for light targets,see LEXFOR Light-Nuclei Reactions (Z<6).

LEXFOR Manual Proposed new entry: Outgoing Particles.

Outgoing Particles(See also Secondary Energy).
Outgoing particles participating in a reaction
Particles resulting from the REACTION to be defined are given in SF3 and SF4.
Sometimes, data are given for partial reactions where the sequence of outgoingprocesses/ 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 apartial reaction. If the author states that the reaction proceeds, e.g., totally in thesequence (n,pn) without any contribution in the sequence (n,np), then the reaction iscoded primarily as (1), above. A comment stating that the reaction proceeds entirelyin the sequence (n,pn) may be added in free text (if this occurs at all) or, alternatively,
both codes may be given in the form of 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 is always 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,γf) cross section: (N,G+F),SEQ,SIG
2. Emission of a primary gamma ray followed by unidentified decays:(n,γx) 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 and SF4 see EXFOR Exchange Formats Manual Chapter 6.
For correlation data on secondary particles, see Differential Data.
Particle Considered
Definition: The particle considered is the particle to which a given function refers,e.g., an angular or energy distribution, or a reaction to a specific particle group. In areaction where only one outgoing particle is specified in SF3, the particle consideredis assumed to be that particle, unless there is an entry in SF7 (Particle Considered).

Outgoing Particles (continued)
When the quantity given refers to a specific secondary particle (e.g., angulardistributions), 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 Exchange Formats Manual Chapter 6 for coding rules.
Examples:a) (…(P,P+A)…,PAR,SIG,A)b) (…(N,P)2-HE-4,,DA,A)c) (…(P,N+P)…,,DA/DA,N/P)

partial cross section for a specific group.
angular distribution of α particles.
double differential cross section,
d2σ/dΩ n /dΩ p .

If the code given in REACTION SF3 is a process code, and the reaction refers to a
specific particle, 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.
(…(N,INL)…,,DA,G)
neutron scattering.
F:The particle considered is ambiguous and should be entered in REACTION SF7.
(…(N,F),,DA,FF)

X:

angular distribution of γ-rays from inelastic

angular distribution of fission fragments.

The particle considered is assumed to be the particle (or nuclide) for which theproduction 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 Exchange Formats Manual Chapter: 7 PART-DET for codingrules). This keyword should be used only in those cases where the particle detected isnot obvious from the quantity given (see preceding).
If the particle detected may be attributed to the decay of a specific nucleus, it may be
coded using the keyword RAD-DET (see EXFOR Chapter 7: RAD-DET for codingrules). 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 thekeywords PART-DET or RAD-DET.
See Dictionary 33 for a list of permissible codes.

Outgoing Particles (continued)
Distinguish the different codes:
DG - decay γ-rays
G- other γ-raysB- - decay electrons (β-)
B+ - decay positrons (β+)
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 center-of-mass energy of the relative motion of a particle pair emitted
in the reaction, the particles are specified in SF7.
Example: REACTION (…(…,…)…,,DA,N+P) angular distribution of n-ppair.
(…(…,…)…,,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 thenumber of secondary particles, and the number of particles is entered as a variable inthe data table, SF4 of the reaction keyword contains the code NPART and SF5
contains the code NUM:
See also Exfor Exchange Formats Manual Chapter 6.
Example:BIB
REACTION…
ENDBIBNOCOMMON
DATA
EN
MEV
…
…
…
ENDDATA(…(…,X)NPART,NUM,…)

PART-OUT
NO-DIM
2.
3.
…

DATA
B
…
…
…

Residual Nucleus Production
In some cases, a given residual nucleus may be produced by more than one reactionchannel, 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 thethreshold for (p,2n2p)), the process code X is entered in SF3 of the REACTION string.
See Production Cross Sections.
(Explanation of (DEF) removed.)

Distribution:
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emmeric.dupont@oecd.org
ganesan@barc.gov.in
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jhchang@kaeri.re.kr
j.roberts@iaea.org
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katakura.junichi@jaea.go.jp
kato@nucl.sci.hokudai.ac.jp
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manokhin@ippe.ru
mmarina@ippe.ru
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nklimova@kinr.kiev.ua

n.otsuka@iaea.org
nrdc@jcprg.org
oblozinsky@bnl.gov
ogritzay@kinr.kiev.ua
otto.schwerer@aon.at
pronyaev@ippe.ru
r.forrest@iaea.org
samaev@obninsk.ru
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