Journal of Nuclear and Radiochemical Sciences, Vol. 3, No. 2, pp. A11-A20, 2002

Reviews
Recoil Studies of Photonuclear Reactions at Intermediate Energies
Hiromitsu Haba*
Cyclotron Center, RIKEN, Wako, Saitama 351-0198, Japan
Received: November 12, 2002; In Final Form: August 7, 2002
A review is given on the recoil studies of photonuclear reactions on complex nuclei at intermediate energies.
Recoils of 167 radionuclides formed in the photonuclear reactions of 27Al, natV, natCu, 93Nb, natAg, natTa, and 197Au,
induced by bremsstrahlung of end-point energies (E0) from 600 to 1100 MeV, have been investigated by the thicktarget thick-catcher method. The recoil velocity from the first step and the mean kinetic energy of the residual
nuclei in the second step were deduced based on the two-step vector velocity model and discussed by comparing
with the reported results on proton-induced reactions. Recoils of 24Na produced from 27Al, natV, natCu, natAg, and197
Au are of special interest from a viewpoint of a change in the production mechanism with respect to target mass.
Reaction yields of 58 and 63 radionuclides produced in the photofission of 197Au and 209Bi, respectively, were alsomeasured at E0 = 300–1100 MeV by a catcher foil technique with the aid of intensive chemical separation. The
fission characteristics such as the charge and mass distributions and the numbers of pre- and post-fission neutrons
were determined. These results were compared with the calculations using the Photon-induced Intranuclear
Cascade Analysis 3 code combined with the Generalized Evaporation Model code.

1. Introduction
Photons are the force carriers of the electromagnetic interaction. The electromagnetic force can act on the scale of thewhole nucleus but also on the smaller scale of nucleons, and so
this interaction is very useful for probing both global and local
properties of the atomic nucleus. At intermediate energies,
photons interact with the nucleus through three mainprocesses; giant dipole resonance (GDR), quasi-deuteronmechanism (QDM), and ∆ resonance, which are characteristic
for the wavelength of incident photons. These initial interactions of photons with nuclei are purely electromagnetic and arequite different from that of hadron-induced reactions initiatedby the strong nucleon-nucleon interaction. It is of interest toinvestigate whether there exist similarities in the final steps inthese two types of nuclear reaction.
By the author’s group, yields of bremsstrahlung-induced
reactions such as photopion reactions,1–4 photospallation,5–8 andphotofragmentation9, 10 of various targets from 7Li to 209Bi havebeen measured radiochemically to extract information on reaction mechanism and nuclear structure. These systematicstudies are also of importance for practical applications such as
astrophysics, medicine, accelerator technology, and nuclear
waste transmutation.
Nuclear recoil experiments give us valuable informationsuch as angular distributions and kinetic energies of productnuclei and deepen our understanding on the reaction mechanism. One of the simplest recoil experiments is done by the
thick-target thick-catcher method. It has been extensively
applied to studies of hadron-induced reactions on various
targets over a wide range of incident particle energy,11–13 butrarely to studies of photonuclear reactions. 14–17 Small crosssections of photonuclear reactions compared with hadroninduced reactions seemed to make the detection of recoil
nuclei arduous.
Recently, we have successfully applied the multiple thicktarget thick-catcher method to photospallation reactions to
examine the effect due to a difference in the initial interactions*Corresponding author. E-mail: haba@riken.go.jp. FAX: +81-48467-9777.

between photon-induced reaction and hadron-induced one
dynamically.18–21 The recoil properties of 137 radionuclides
formed in the photospallations of 27Al, natV, natCu, 93Nb, natAg,
nat
Ta, and 197Au, induced by bremsstrahlung of end-point energies (E0) from 600 to 1100 MeV, have been investigated basedon the two-step vector velocity model.18–21 The recoil properties such as the recoil velocity v from the first step and the
kinetic energy T of the residual nuclei in the second step werededuced and discussed by comparing with those of protoninduced reactions.20, 21
The nuclear recoil experiment by the thick-target thickcatcher method is very useful to obtain fission yields as well as
recoil properties, because the energetic fission fragments withsmall yields can be separated effectively in the catcher foil
from the relatively less energetic spallation residues with large
yields. Photofissions at intermediate energies are expected to
be unique for investigating the complex dynamics of excitationin heavy nuclei, because photons interact electromagneticallywith nuclei through GDR, QDM, and ∆ resonance. For preactinide nuclei such as 197Au and 209Bi, the photofission processes
opened by QDM and ∆ resonance are especially important due
to their high fission thresholds (> 20 MeV) that suppress thefission channels opened by GDR. Thus a photon sees all
nucleons inside a nucleus identically and interacts with anucleon-nucleon pair or a single nucleon, transferring its
kinetic energy effectively but comparatively little angularmomentum to the nucleus. The fission process must be
regarded as a collective process of the nucleus. It is interesting
how these local excitations are propagated in nuclear matterand transferred to the collective nuclear excitation.
Photofission, however, is not very well understood at energies of interest, because fission yields are quite lacking
compared with spallation and fragmentation yields. The situation is the same with proton-induced reactions. Recently,
Duijvestijn et al.22 measured cross sections of proton-induced
fissions of natW, 197Au, natPb, 208Pb, and 232Th at a proton energyof 190 MeV. They compared the fission cross sections withtheoretical calculations using the intranuclear cascade code
LAHET,23 and found that the calculation severely underestimates the cross sections for the preactinides and overestimatesin general the width of the mass distribution. The absence of a

© 2002 The Japan Society of Nuclear and Radiochemical Sciences
Published on Web 12/28/2002

Haba

A12 J. Nucl. Radiochem. Sci., Vol. 3, No. 2, 2002
reliable theoretical model to predict fission yields as well as
the need for experimental yields has motivated us to investigate photofission processes of preactinides. Quite recently, wemeasured recoil properties and yields of radionuclides
produced in the photofission of 197Au and 209Bi at E0=300–1100
MeV by a catcher foil technique with the aid of intensive
chemical separation. 24–26 The recoil properties such as theforward-to-backward ratio F/B and the kinetic energy T of theresidual nuclei were discussed by comparing with those ofphotospallation products and also with the literature data for
proton-induced reactions.26 Furthermore, fission characteristics such as the charge and mass distributions and the numbersof pre- and post-fission neutrons were determined based on the
58 and 63 fission yields on 197Au and 209Bi, respectively.24, 26
By the author’s group, the reaction yields of photopion andphotospallation reactions and the kinetic energies of the photospallation products were systematically compared with the
Photon-induced Intranuclear Cascade Analysis (PICA) codedeveloped by Gabriel and coworkers,27, 28 and various information on reaction mechanism and nuclear structure was
extracted.1–4, 8, 18–21 Recently, the original code was modified
by Fu29 and Sato et al.30, 31 and the fission process was considered for the first time in the code based on the Generalized
Evaporation Model (GEM) code developed by Furihata. 32
Comparisons of the experimental results with the latest PICA
calculations31 are under study in our group.26, 33, 34
In the following, our recoil studies of photonuclear reactionsat intermediate energies are reviewed based on the cumulative
results in the series of the author’s papers.18–21, 24–26, 33, 34
2. Experimental Procedures
Irradiations by bremsstrahlung beams with end-point energies of E0 = 300–1100 MeV were carried out using the 1.3GeV electron synchrotron of the High Energy Accelerator
Research Organization (KEK) at Tanashi. A 50 µm thick Pt
foil was used as a radiator for bremsstrahlung production, andthe beams were collimated to 20 mm in diameter at the irradiation position. The targets consisted of a stack of 5–50 sets of atarget foil of 25 × 25 mm2 in size sandwiched by one pair of
3.5 or 7.0 mg cm−2 thick Mylar foils of the same size, whichcollected the recoil nuclei in the forward and backward directions with respect to the beam direction. The target thicknesses were 6.6, 14, 22, 24, 32, 32, 90, and 900 mg cm−2 for
27
Al, natV, natCu, 93Nb, natAg, natTa, 197Au, and 209Bi, respectively.
The photon intensities evaluated from the monitor reaction of27
Al(γ, 2pn)24Na (Ref. 35) were 109–1010 equivalent quanta persecond (eq.q. s−1). The typical irradiation periods were 3 h for
27
Al, natV, natCu, 93Nb, and 209Bi, 4 h for natAg and natTa, and 5 h
for 197Au. After irradiation, chemical separation of K, Sc, Fe,
Ni, Zn, Ga, As, Rb, Sr, Y, Zr, Nb, Mo, Ag, Ba, and rare earth
elements (REE) from Au, and of Fe, Ga, As, Br, Sr, Y, Zr, Nb,
Ag, I, and Ba from Bi was employed for part of the targets todetect radionuclides with small yields. In addition, the chemical separation of Sc, Ba, and REE from the Au target and its
catchers was performed in the separate irradiations. The
details of the chemical procedures are described in References21, 26, and 36. Some selected target foils and all of theforward and backward catchers from one target pile as well as
the chemically separated samples were assayed for radioactivities with Ge detectors.
3. PICA3/GEM Calculation
Gabriel and coworkers 2 7 , 2 8 developed a Monte-Carlo
intranuclear cascade-evaporation analysis code for photonuclear reactions: Photon-induced Intranuclear Cascade Analysis(PICA). This calculational code is based on the Bertini
version 37 of the intranuclear cascade and differs only withrespect to the initial interactions. The initial interactions
considered are QDM and the single pion photoproduction
through ∆ resonance. The code is valid for photon energies
from 30 to 400 MeV. Recently, Fu29 and Sato et al.30, 31 modified the original code and named the new one as PICA3. Theenergy limit was extended to E0 = 0–3.5 GeV by considering
GDR and multiple-pion production channels.29, 30 The angular
distribution of nucleons produced by the quasi-deuteron disintegration as well as its cross section was revised.30 In addition,
the nucleon-nucleon scattering cross section used in the
cascade process, the level density parameter and the mass
formula used in the evaporation process were updated.30 The
nuclear medium effect and the nuclear shadowing effect werealso considered in the photopion production cross sections. 31
On the other hand, Furihata32 developed the GEM code basedon the Generalized Evaporation Model and the Rutherford
Appleton Laboratory (RAL) model by Atchison.38 Parameters
used in the RAL model38 which determine the mass, charge,
and kinetic energy distributions of fission fragments werereevaluated. Furihata 32 estimated the cross sections for
nuclides produced from the proton-induced reactions of 208Pb
and 197 Au using a combination of the intranuclear cascade
model (INC) in the LAHET code23 and the GEM code.32 It
was found that the INC/GEM code32 reproduces successfully
the cross sections for fission fragments as well as light fragments.
Quite recently, Sato et al.31 combined the GEM code32 with
the PICA3 code 31 to describe the evaporation and fission
processes in the photonuclear reactions. In this paper, thereproducibility of the kinetic energies and reaction yields ofresidual nuclei by the PICA3/GEM code 31 was examined
systematically. The input parameters recommended in theoriginal papers28, 31, 32 were used in the present calculation.
4. Results and Discussion
4.1. Recoil Properties of Photospallation Products on
Complex Nuclei
4.1.1. Recoil Fractions and Effective Mean Ranges.
Radioactivities of 1, 14, 24, 26, 31, 21, and 20 nuclides produced from 27 Al, nat V, nat Cu, 93 Nb, nat Ag, nat Ta, and 197 Au,
respectively, were identified both in the target and catcher
foils. From the fractions of each nuclide measured in the forward and backward catcher foils, expressed as F = NF/(NF + NB
+ Ntarget) and B = NB/(NF + NB + Ntarget), N being the number ofatoms, the effective mean ranges FW and BW were obtained bymultiplying the target thickness W in units of µg cm−2. All of
the FW and BW values obtained in the present work were
found to be independent of E0 above 600 MeV. In our previous papers,5–7 yield measurements of the photospallation reactions of various targets ranging from natV to 197Au were reported. From the slope parameter P of the mass-yield curve in theempirical charge and mass distribution formula (CDMD),39
which is an indirect measure of the average excitation energy
transferred in the spalling nuclei, it was found that the excitation energy seems to saturate at energies higher than 600 MeV.
The E 0 -independece of FW and BW obtained in this recoil
study is consistent with that of the slope parameter P, and indicates that the photons responsible for the production of these
nuclides are mostly of energies lower than 600 MeV.
Therefore, the following discussion proceeds based on the
average quantities above 600 MeV.
As an example, the averaged values of FW and BW are
shown by open and closed circles, respectively, as a functionof mass difference ∆A between a product (Ap) and a target (At )in Figure 1a for natCu and Figure 1b for 197Au. The FW values
are higher than the corresponding BW, and both increase inparallel with an increase of ∆A. This increasing trend with ∆A
can be divided into two components: one is a steep increase forRecoil Studies of Photonuclear Reactions

J. Nucl. Radiochem. Sci., Vol. 3, No. 2, 2002 A13
6

F/B

4
3
2
1

102

0
6
61Cu

(b) natCu

5

F/B

FW and BW / g cm-2 of Cu(a) natV

5(a) natCu

103

101

4
3
2
1
0
6

60Cu

(c) 93Nb

5F/B(b) 197Au

4
3
2
1
0
6

102

(d) natAg

F/B

5
192Au

4
3
2

194Au

1

101

0
6

(e) natTa

5

F/B

FW and BW / g cm-2 of Au

100
103

100
196Au

3
2

10

20

∆A

30

40

1

50

Figure 1. Averaged mean ranges FW (open symbols) and BW (closed
symbols) at E0 ≥ 600 MeV as a function of mass difference ∆A for (a)natCu and (b) 197Au. The dashed curves are to guide the eye. (From
Reference 21)06(f) 197Au

5

F/B

0

4

4
3
2
1
0

0

10

20

∆A

30

40

50

Figure 2. Forward-to-backward ratios F/B at E0 ≥ 600 MeV as afunction of ∆A for (a) natV, (b) natCu, (c) 93Nb, (d) natAg, (e) natTa, and(f) 197Au. (From Reference 21)

recoiling residual nucleus is resolved into two velocity components, v and V, corresponding to the cascade step and the deexcitation or breakup step of the reaction, respectively. The cascade component v is assumed to be parallel to the beam direction. The velocity V must be symmetric in the moving system,
and is assumed to be isotropic. Furthermore, if the range of arecoiling nucleus in the target material Rl can be related to its
velocity by an expression of Rl = CvlN, where C and N are constants, and if v/V is small, the following relations can bederived:
13

v 2
.
V

(1)

13

BW =

R0
2(N + 2) v v (N +1)2
+
1−
4
3
V
4

v 2
,
V
123 123R02(N + 2) v v (N +1)2
1+
+
4
3
V
4

13

FW =

13

123 123the (γ, xn) (x ≥ 1) products mainly produced by GDR and theother is a gentle increase for the (γ, xnyp) (x, y ≥ 1) products
mainly produced by ∆ resonance. However, this difference is
not very clear for the (γ, xn) reactions with higher multiplicities of x ≥ 4, due to negligibly small contributions of GDR (seealso Figure 1 in Reference 21 for natV, 93Nb, natAg, and natTa).
The existence of these two components in photospallation waspreviously suggested in yield measurements,6, 7 in which thereaction yields of the (γ, xn) (x ≥ 1) products deviate fromthose deduced by the CDMD formula; 39 a new empiricalexpression for this type of reaction was proposed.
The forward-to-backward ratios F/B at E0 ≥ 600 MeV areplotted as a function of ∆A in Figure 2 for natV, natCu, 93Nb,
nat
Ag, nat Ta, and 197 Au. As is expected from the parallel
increases of FW and BW in Figure 1, the F/B ratios are now
shown to be independent of ∆A, and their weighted meanvalues are 2.3±0.9 for natV, 2.4±0.5 for natCu, 2.8±0.5 for 93Nb,
2.7±0.4 for nat Ag, 2.9±0.4 for nat Ta, and 2.5±0.6 for 197 Au.
Noted is that these average values are all equal irrespective ofthe target within the associated errors. On the other hand, it
was found from a literature survey that the F/B ratios of typicalspallation products from proton-induced reactions at incident
proton energies of Ep ≤ 3 GeV vary with ∆A, and decrease withan increase of Ep, but become Ep- and ∆A-independent above 3
GeV. It seems interesting that this constant F/B ratio of
proton-induced reactions at Ep > 3 GeV is equal to that of thephoton-induced reactions at E0 ≥ 600 MeV. The implicationsof this behavior are discussed in the following section in termsof the two-step vector velocity analysis.
4.1.2. Analysis by the Two-Step Vector Velocity Model. The
measured recoil data may be used to derive some recoil parameters by means of the vector velocity model embodying thetwo-step mechanism commonly invoked in high-energy proton
reactions. In the present work, the two-step vector velocity
model developed by Winsberg40 was employed for this purpose. According to this model, the observable velocity vl of a

The quantity R 0 is the mean range in the target material
corresponding to the recoil velocity V, so that R0 = CVN. The
R0 and v/V were calculated from the measured quantities of FW
and BW by using above two equations. The calculated R0 wasconverted to the kinetic energy T of the residual nucleus byusing the range-energy table. The range-energy relation used
to convert R0 to T and to obtain the values C and N was calculated by the SRIM2000 code developed by Ziegler et al.41 The
forward velocity v was calculated from the v/V and T values.
4.1.3. Mean Range R0 and Kinematic Parameters v and T.
In Figure 3 the mean ranges R0 in units of mg cm−2 of target
foil of the (γ, xnyp) (x, y ≥ 1) products at E0 ≥ 600 MeV areshown as a function of ∆A by different symbols for natV, natCu,
93
Nb, natAg, natTa, and 197Au. R0 increases smoothly with an

Haba

A14 J. Nucl. Radiochem. Sci., Vol. 3, No. 2, 2002
0.4

3.5

(a)

natV
natCu
93Nb

0.3

natAg

2.5

v / (MeV/nucl.)1/2

R0 / mg cm-2 of each metal foi l

3.0

natTa
197Au

2.0

1.5

0.2

0.1

1.0

0.5

0.0
20

0.0
0

10

20

30

40

50

This work E0=600-1100 MeV∆Aincrease of ∆A as shown by different lines for the respective
targets in Figure 3. It was found that R0 is well reproduced bya relation R 0 = a(A t /∆A–1) −b and that parameters a and b
obtained by the least-squares fittings are a smooth function of
atomic number of target Z t.21 This relationship may be used to
predict the unmeasured mean ranges and to estimate the recoil
losses from target foils for the typical photospallations on various targets. Also, this systematic is available for protoninduced spallation, irrespectively of Ep, due to the same R0(and T) values in proton-induced reaction as those in photon
reactions.
The forward velocity v is a good parameter to estimate themomentum transferred to an intermediate nucleus in the firstcascade step and is related to the deposited excitation energy.
On the other hand, the average recoil energy T imparted to aresidual recoiling nucleus is a convenient parameter to investigate the second evaporation step of the reaction. As an
example, the variations of v and T at E0 ≥ 600 MeV are shown
as a function of ∆A by large open circles for natCu in Figures 4aand 4b, respectively. The cascade velocity v increases linearlywith an increase of ∆A, indicating that the higher excitationenergy is deposited on an intermediate nucleus to form aresidual nucleus with a larger ∆A. The kinetic energy T also
increases almost linearly with an increase of ∆A, as explainedby a random-walk theory.13 Proton results on natCu (Refs. 42−47) are available at various proton energies (Ep), as indicatedin the inset of Figure 4b. The v values at Ep ≤ 3 GeV (opensymbols) are apparently higher than those of the photon reactions and decrease with an increase of Ep up to 3 GeV. The v
values at Ep > 3 GeV, indicated by closed symbols, are almost
the same as those of the photon reactions. On the other hand,all of the T values of the proton reactions are about the same as
those of the photon reactions, irrespective of Ep.
From a comparison with the proton results for other targetsof 27 Al, nat V, nat Ag, nat Ta, and 197 Au (Refs. 20 and 21), it isconcluded that for typical spallation the v values of proton
reactions at Ep ≤ 3 GeV are higher than those of photon reactions at E0 ≥ 600 MeV and decrease with an increase of Ep up
to around Ep = 3 GeV, and become constant at higher energies.
This distinct difference of the v values in the two types ofnuclear reaction at the lower-energy region may be attributed
to the lower momentum transferred in the initial electromagnetic interaction in photon reactions. The steep decrease of v
in proton reactions at E p ≤ 3 GeV is due to the increasing
nuclear transparency to the incoming proton; the difference
disappears at proton energies above 3 GeV, where themomentum transfer in proton reactions is almost the same as(b)

Lagarde-Simonoff et al. [42] E p=150 MeV
Lagarde-Simonoff et al. [42] E p=600 MeV
Crespo et al. [43] Ep=700 MeV

15Cumming et al. [46] E p=810 MeV
Crespo et al. [43] Ep=3 GeV

T / MeVFigure 3. Mean ranges R0 in the second step at E0 ≥ 600 MeV as afunction of ∆A for natV (open circles), natCu (closed squares), 93Nb
(open triangles), n a t Ag (closed inverse triangles), n a t Ta (open
diamonds), and 197Au (closed diamonds). (From Reference 21)

Cumming et al. [45] E p=28 GeV
Porile and Tanaka [44] E p=29 GeV

10Cole and Porile [47] Ep=400 GeV
PICA3/GEM E0=600-1100 MeV [31]

5

0
0

10

20

∆A

30

40

50

Figure 4. (a) Forward velocity v in the first step and (b) kinetic
energy T in the second step as a function of ∆A for natCu. See text forthe details. (From Reference 33)

that in photon reactions. On the other hand, T in proton reactions seems to be independent of Ep in the energy region cited
above and agrees well with those of photon reactions at E0 ≥600 MeV. This consistency of the T values suggests that themechanism of the second deexcitation step is very similar inboth photon and proton reactions.
The reproducibility of the kinetic energies T by the
PICA3/GEM code31 was examined. The calculated T values
for natCu at E0 = 600–1100 MeV are indicated by crosses forthe nuclides corresponding to the measured ones in Figure
4b. The calculated T values increase with an increase of ∆A
in a similar way as the experimental results. In order to checkthe reproducibility of the PICA3/GEM code 31 quantitatively,
the ratios of the calculated T to the experimental T,
T(Cal.)/T(Exp.), are shown as a function of ∆A for natV, natCu,
93
Nb, nat Ag, nat Ta, and 197 Au in Figure 5. The dashed lines
represent T(Cal.)/T(Exp.) = 1. The PICA3/GEM code31 reproduces the experimental results for natV, natCu, 93Nb, and natAg
fairly well, while the code underestimates the experiments forthe heavier targets of natTa and 197Au. The underestimation of
T by the PICA3/GEM code31 in the heavy target region implys
that the smaller separation energies of emitted nucleons are
assumed for heavy targets in the calculation. The discrepancy
may be explained by nuclear medium effects that would
become progressively significant in heavier nuclei; 4 thesmooth variation of the (γ, π−xn) yields as a function of theneutron-to-proton ratio of the target (N/Z) t changes its characteristics at (N/Z) t = 1.30–1.40, corresponding to At = 100–130,
implying higher excitation energies due to progressively larger
medium effects in nuclei with At > 100.
4.1.4. Systematization of the Second Step. Winsberg13 suggested that εs = T/(∆A/At ), which represents the average energy
carried off by an evaporated nucleon, is a good parameter tosystematize the second step, and found that εs is independent ofRecoil Studies of Photonuclear Reactions

J. Nucl. Radiochem. Sci., Vol. 3, No. 2, 2002 A15
30

T(Cal.)/T(Exp.)101(a) natV

25

100

20

ε s / MeV

T(Cal.)/T(Exp.)

10-1
101

(b) natCu
100

15
10

T(Cal.)/T(Exp.)

10-1
101

(c) 93Nb

5

100

0

T(Cal.)/T(Exp.)(d) natAg

T(Cal.)/T(Exp.)

10-1
101

(e) natTa
100

10-1
101

T(Cal.)/T(Exp.)

50

100

150

200

Figure 6. Parameter εs as a function of At for photon reaction (opencircles connected by a solid line) and proton reaction (closed squares
connected by a dashed line). (From Reference 21)

100(f) 197Au
100

10-1

0

At

10-1
101

0

10

20

∆A

30

40

50

Figure 5. Ratio of the calculated T by the PICA3/GEM code31 to theexperimental T at E0 ≥ 600 MeV, T(Cal.)/T(Exp.), as a function of ∆A
for (a) natV, (b) natCu, (c) 93Nb, (d) natAg, (e) natTa, and (f) 197Au. (From
Reference 33)∆A/At and also of At for typical spallation reactions induced byprotons. We applied this systematization for the photospallation. The εs values of the (γ, xn) products increase with anincrease of ∆A/At and they are obviously lower than those ofthe (γ, xnyp) products. The latter is independent of ∆A/At , asin proton reactions, and the weighted mean values are 13±2,
13±3, 17±3, 16±1, 15±4, and 16±5 MeV for natV, natCu, 93Nb,
nat
Ag, natTa, and 197Au, respectively. The average εs values areplotted in Figure 6 as a function of At by open circles together
with those of the proton reactions45−57 by closed squares. The
details for the proton data were described in Reference 21.
The εs values of both the photon and proton reactions increaseslightly with an increase of A t up to around A t = 100 andbecome almost constant at heavier targets. This At-dependentfeature of εs has not been reported previously as far as we areaware.
It was reported5, 7 that there are linear relationships between
the neutron-to-proton ratios of the most probable product,(N/Z) p, and those of targets, (N/Z) t , both in the photon- andproton- (and α-) spallation of natV–197Au. The slope of (N/Z) p
against (N/Z) t for the photospallation is steeper than that for
proton- (and α-) spallation, and the (N/Z) p of photospallation isshifted to the more neutron rich side for the targets of (N/Z) t >1.2 with respect to that of proton- (and α-) spallation. Thissuggests that the average excitation energy of cascade residues
in photospallation is lower than that in hadron spallation. Theεs values of the photon reactions obtained in the present work
are almost equal to those of the proton reactions for 27Al of(N/Z) t = 1.08 and natCu of (N/Z) t = 1.19, but systematicallylower for the targets of (N/Z) t > 1.2, such as natAg of (N/Z) t =1.30, natTa of (N/Z) t = 1.48, and 197Au of (N/Z) t = 1.49. Thisvariation of εs shown in Figure 6 is consistent with the abovementioned findings of At-dependent features of the photospallation and photopion reaction yields,4, 7 though fairly large
errors are accompanied with the εs values.
4.2. Photofission of 197Au and 209Bi
4.2.1. Recoil Properties of the Photofission Products from197
Au. The 29 radionuclides with A = 24–131 produced from197
Au were identified in the target and catcher foils in addition
to the 20 with A = 152–197 cited above. Their effective mean
ranges FW and BW were also found to be independent of E0 at
the studied E0. The F/B ratios at E0 ≥ 600 MeV are plotted byopen circles as a function of mass difference ∆A in Figure 7a.
The F/B ratio represents the extent of forward peaking of therecoil, and thus is a simplified measure of the angular distribution of the product nuclei. As mentioned in sect. 4.1.1, the F/B
ratio for typical photospallation products is independent of ∆A
and also of At , and the weighted mean value for 197Au at ∆A ≤45 is 2.5±0.6 as indicated by a dashed line in Figure 7a. The
F/B ratios at ∆A ≥ 66 are also independent of ∆A, but theweighted mean value of F/B = 1.1±0.1 shown by a solid line in
Figure 7a is apparently lower than that for the photospallation
products at ∆A ≤ 45, indicating the isotropic angular distribution of the product nuclei. The proton results47, 53, 55, 58 are also
included in Figure 7a by the different symbols as shown in theinset of the figure. The F/B ratios at Ep = 0.58, 1, and 3 GeV,
which are shown by open symbols, are apparently higher thanthose at the higher Ep (closed symbols) and also those of thephoton reaction (open circles). The F/B ratios at Ep ≤ 3 GeV
increase with an increase of ∆A and reach peaks around ∆A =40 at Ep = 1 GeV and around ∆A = 55 at Ep = 3 GeV. After thepeak, the F/B decreases with an increase of ∆A and almost levels off at ∆A ≥ 87. The F/B values of the proton reactions
decrease with an increase of Ep up to Ep = 3 GeV, but becomes
Ep-independent at the higher Ep (closed symbols). It is notedthat the Ep-independent F/B values of the proton reactions at Ep> 3 GeV are equal to those of the photon reaction at E 0 =600–1100 MeV except for the results of 196Au and 194Au produced by the direct reactions.
The kinetic energies T of the product nuclei were evaluatedbased on the same procedure as described in sect. 4.1.2. In
Figure 7b, the T values at E0 ≥ 600 MeV are shown as a function of ∆A by open circles. At ∆A ≤ 45 the T increases with anincrease of ∆A, showing the two components; one is a steep
increase for the (γ, xn) (x ≥ 1) products 196,194,192Au (a dottedcurve), and the other is a gradual increase for the (γ, xnyp) (x, y≥ 1) products (a solid curve). The increasing trend for the

Haba

A16 J. Nucl. Radiochem. Sci., Vol. 3, No. 2, 2002
3.0

10

(a)

(a)

This work E0=600-1100 MeV
Ross and Baechmann E p=580 MeV [58]Kaufman et al. E p=1 GeV [55]Kaufman et al. E p=3 GeV [55]Kaufman et al. E p=11.5 GeV [55]Cumming and Baechmann Ep=28 GeV [53]Kaufman et al. E p=28 GeV [55]Kaufman et al. E p=300 GeV [55]Cole and Porile E p=400 GeV [47]

F/B

6

2.0

F/B

8

2.5

1.5

4
1.0

2

0.5

0.0

0
103

1.5

(b)

(b)

102

This work E0=600-1100 MeV
Ross and Baechmann E p=580 MeV [58]Kaufman et al. E p=1 GeV [55]Kaufman et al. E p=3 GeV [55]Kaufman et al. E p=11.5 GeV [55]Cumming and Baechmann Ep=28 GeV [53]Kaufman et al. E p=28 GeV [55]Kaufman et al. E p=300 GeV [55]Cole and Porile E p=400 GeV [47]
PICA3/GEM E0=600-1100 MeV [31]Komar et al. E0=1000 MeV [59]

100
192Au

10-1

10-2

194Au

T/EC

T / MeV

1.0

101

0.5

196Au

0

0.0

50

100

150

200

∆A

0

50

100

150

200

At

Figure 7. (a) Forward-to-backward ratios F/B and (b) kinetic energy
T for 197Au at E0 ≥ 600 MeV as a function of ∆A. See text for thedetails. (From References 25 and 34)

Figure 8. (a) Forward-to-backward ratios and (b) F/B and ratios T/EC
of 24Na produced from 27Al, natV, natCu, natAg, and 197Au at E0 ≥ 600
MeV as a function of the target mass number At. (From Reference 25)

latter component is well explained in terms of a random-walktheory for typical spallation13 (see sect. 4.1.4). In this theory,the εs values are independent of ∆A/At and the average εs value
is 16±5 MeV. On the other hand, the T values at ∆A > 45 arequite higher than those extrapolated from the spallation trendat ∆A ≤ 45. The εs values are more than 50 MeV, implying thedifferent production mechanism from typical spallation.
Komar et al. 59 measured the kinetic energies of coincident
fragment pairs in the photofission of 197Au at E0 = 1000 MeV
by using the semiconductor detectors. Their results are indicated by a dashed curve in Figure 7b. The T values obtained
radiochemically in the present work seem to be well consistent
with the physical measurements by Komar et al.59 except for
those of barium isotopes at ∆A = 66, 68, and 69. The smaller T
values of Ba isotopes may indicate that their productions are
based on both fission and spallation. The proton results47, 53, 55, 58
are shown in Figure 7b for a comparison. At ∆A ≤ 66 the Tvalues for the proton reactions are consistent with each other,irrespectively of Ep, and also with those of the photon reaction
at E0 ≥ 600 MeV (see sect. 4.1.3). On the other hand, the Tvalues at ∆A > 66 decrease with an increase of Ep and become
constant at Ep > 3 GeV (closed symbols). This decreasing
trend is explained as a change in the reaction mechanism fromfission to deep spallation. In case of the photon reaction, theeffective photon energies are lower than 600 MeV and thevariation of T is not found above 600 MeV. The T values
calculated by the PICA3/GEM code31 at E0 = 600–1100 MeV
are indicated by crosses in Figure 7b. The PICA3/GEM code31
reproduces the T values of the products with ∆A > 45, which
are formed in the two-body breakup process, though the code
underestimates by a factor of about 0.7 for the spallation products with ∆A ≤ 45 (see sect. 4.1.3).
4.2.2. Production of 24Na. Recoils of 24Na make it possible
to trace how the production mechanism of light nuclei changes
with target mass At . The F/B ratios of 24Na produced from27
Al, natV, natCu, natAg, and 197Au are shown in Figure 8a byopen circles as a function of At . The F/B values for 27Al, natV,and natCu are about 2 and they agree with the photospallation
trend (see sect. 4.1.1). However, the F/B values decrease gradually with an increase of At as a whole and attain to almost
unity for 197Au. This variation indicates that the change of theangular distribution of 24Na from the forward-peaking distribution to the isotropic distribution when At increases.
It may also be interesting to compare the observed mean
kinetic energy T of 24 Na with the energy E C acquired by
Coulomb repulsion in the two-body breakup process. The
ratio of T to EC would be small if 24Na is produced as a residueof nucleon evaporation, and would be of the order of unity if
the kinetic energy of 24Na is acquired as a results of Coulomb
repulsion in the two-body breakup process such as fission or
fragmentation. Thus, the T/EC ratios are shown as a functionof At in Figure 8b. The T/EC ratios are about 0.5 for 27Al, natV,and natCu, and are almost unity for natAg and 197Au.
The variations of F/B and T/EC with At may be explained asa result of the transition of the reaction mechanism from spallation to fission or fragmentation. As mentioned in sect. 4.1.4,
the kinetic energy T of typical photospallation products is wellparameterized by εs ; the εs values are all in the range of 10–20
MeV. The ε s values for 24Na from 27Al, natV, and natCu are
11.9±1.4, 18.9±3.1, and 21±10 MeV, respectively, and theyagree with the spallation trend. However, the ε s values of
51±13 MeV for natAg and of 96±11 MeV for 197Au are quite
high compared with those for the lighter targets, implying thedifferent reaction mechanism from spallation. It is also notedthat the existence of two nuclear processes in the photoproduction of 24Na was found in the mass dependence of the reaction
yields;9, 10 the yields decrease exponentially with an increase of
A t (spallation), but suddenly change the slope to a gradualincrease around At = 100 (fragmentation). Recently, the yields
of 7,10Be, 22,24Na, and 28Mg from 197Au were measured by theauthor’s group.10 They are more than one order of magnitude
higher than those extrapolated from the mass yield curve of

Recoil Studies of Photonuclear Reactions

J. Nucl. Radiochem. Sci., Vol. 3, No. 2, 2002 A17

fission, indicating a different reaction mechanism from fission;
fragmentation.
4.2.3. Charge and Mass Yield Distributions. We measured
the yields of 58 radionuclides with A = 42–131 formed in thephotofission of 197 Au at E 0 = 300–1100 MeV. In the 209 Bi
experiments, those of 63 nuclides with A = 56–135 wereobtained. All of the yields increase steeply with an increase of
E0 up to 600 MeV and increase gradually above 600 MeV,
indicating the resonance-type excitation function attributed to∆ resonance.
The charge distribution Y CD (Z) among the isobars of acertain product mass number A was assumed to be represented
by the following Gaussian function:(Z−Z p )2
CZ

123

123

YCD (Z) = YCD (Zp) · exp –(2)

where YCD(Zp) is the maximum yield of the charge distribution,
Zp being the most probable charge. The width parameter CZ
was assumed to be constant, irrespectively of A, and Zp to be a
linear function of A, i.e., Z p = RA + S. By assuming theunchanged charge distribution (UCD) hypothesis, the parameter R is related to a charge-to-mass ratio of a fissioning
nucleus as R = Zt / (At –vpre), vpre being the number of prefission
neutrons. The parameter S is a measure of the number of
average post fission neutrons v post as S = Z t v post / (A t –v pre ).
Equation 2 was fitted to the experimental yields by a leastsquares method, and four free parameters YCD(Zp), CZ, R, and S
were determined.

As an example, the charge distributions obtained for 209Bi at
E0 = 1000 MeV are shown in Figure 9 by solid curves for the
representative 10 mass chains of A = 72, 83, 86, 88, 95, 96, 97,
103, 105, and 126, in which more than two yield data are available. The independent yields (I), the cumulative yields by β−decay (C–), and by β+ decay and/or electron capture (C+) are
shown by open circles, closed triangles, and closed squares,
respectively. The cumulative yields are shown by a dottedcurve for C– and by a dashed curve for C+ by integrating theindependent YCD(Z) curve. The results of these fittings are
fairly good and the present assumptions in eq 2 are reasonable.
The yields calculated by the PICA3/GEM code31 are comparedby crosses in Figure 9. They show the symmetric charge
distribution with almost the same width as the experiments.
The maximum yield values are approximately comparable tothe experimental ones, though slight differences in the peak
position (Zp) are shown; Zp is reproduced well for A = 96–105,
but is overestimated for lower A and underestimated for A =126. The more detailed comparison is given below referring to
the charge distribution parameters.
The full width at half maximum of the charge distribution
FWHMCD in charge unit (c.u.) and the parameters R and S were
found to be independent of E 0 above 600 MeV, and theirweighted mean values are tabulated in Table 1. The FWHMCD
values of 197Au and 209Bi are consistent with each other. The R
value of 0.424±0.001 for 197Au implies 11-neutron emission
before fission (vpre = 11±1) as deduced from the UCD assumption. On the other hand, the S value of 0.7±0.1 implies the

TABLE 1: Charge and Mass Yield Distribution Parameters in the Photofission of 197Au and 209Bi at E0 ≥ 600 MeV (From
Reference 34)
Target

FWHMCD [c.u.]RS

Ap [m.u.]

FWHMMD [m.u.]Exp.

2.2 ± 0.1

0.424 ± 0.001

0.7 ± 0.1

92 ± 139 ± 1

PICA3/GEM

2.2 ± 0.1

0.423 ± 0.001

1.5 ± 0.1

86 ± 137 ± 2Exp.

2.1 ± 0.1

0.421 ± 0.001

0.6 ± 0.1

96 ± 133 ± 1

PICA3/GEM

2.6 ± 0.1

0.403 ± 0.001

2.6 ± 0.1

94 ± 134 ± 1

197

Au

209

Bi

Y i elds / µb eq.q -1

103(a) A = 72(b) A = 83(d) A = 88(e) A = 95

102

101

100
27 28 29 30 31 32 33 34 35

32 33 34 35 36 37 38 39 40

33 34 35 36 37 38 39 40 41

34 35 36 37 38 39 40 41 42

37 38 39 40 41 42 43 44 45

Z

Z

Z

Z

Z
103

Y i elds / µb eq.q -1(c) A = 86(f) A = 96(g) A = 97(h) A = 103(i) A = 105(j) A = 126

102

101

100
37 38 39 40 41 42 43 44 45

Z

38 39 40 41 42 43 44 45 46

40 41 42 43 44 45 46 47 48

41 42 43 44 45 46 47 48 49

50 51 52 53 54 55 56 57 58

Z

Z

Z

Z

Figure 9. Charge distributions for mass chains of (a) 72, (b) 83, (c) 86, (d) 88, (e) 95, (f) 96, (g) 97, (h) 103, (i) 105, and (j) 126 at E0 = 1000 MeV.
See text for the details. (From Reference 26)

Haba

A18 J. Nucl. Radiochem. Sci., Vol. 3, No. 2, 2002
average 1.7±0.3 post neutrons (vpost). The vpre and vpost values
for 209 Bi are 12±1 and 1.4±0.3, respectively, and they arecomparable with those for 197Au.
The E0-independent trend of the charge distribution parameters at E0 ≥ 600 MeV is reproduced by the PICA3/GEM code,31
and the average values of each parameter are compared inTable 1. The FWHMCD value calculated for 197Au is consistent
with the experimental result, while that for 209Bi is higher by
0.5 c.u. Also noted is that the R value calculated for 209Bi isquite smaller than the experimental one, indicating smaller vpre
value in the calculation. On the other hand, the S values forboth 197Au and 209Bi are more than two times higher than theexperiments. The overestimation of S by the PICA3/GEM
code31 means that a higher excitation energy of fission fragments is assumed in the calculation.
Based on the charge distribution parameters, the total chain
yields in unit of µb per equivalent quanta (µb eq.q.−1) were
calculated. As an example, the total chain yields obtained at
E0 = 1000 MeV are shown in Figure 10 as a function of A by
open circles and open squares for 197Au and 209Bi, respectively.
These mass yield distributions are well reproduced by aGaussian function as shown in Figure 10 by solid and dashedcurves for 197Au and 209Bi, respectively. The most probablemass (Ap) and the full width at half maximum (FWHMMD) of
the mass yield distribution were found to be independent of E0
above 600 MeV, and the weighted mean values are tabulated
in Table 1. The Ap value obtained for 197Au is smaller by 4
m.u. than that for 209Bi, while the FWHMMD is larger by 6 m.u.
The total fission yield of 10±1 mb eq.q.−1 for 209Bi at E0 = 1000
MeV is about three times higher than the value of 3.2±0.1 mb
eq.q. −1 for 197 Au. These differences are considered to beimportant clues to the excitation energy and nuclear structureof fissioning preactinide nuclei in the neutron-deficient region.
The mass yields calculated by the PICA3/GEM code31 at E0= 1000 MeV are shown Figure 10 by closed symbols. They
also show the symmetric mass yield distribution. As
mentioned above, however, large differences in the charge
distribution parameters were found between the experimental
results and the PICA3/GEM calculation. 31 There should besome discrepancies in the meaning even if the A p and/or
FWHMMD values are reproduced by the PICA3/GEM calculation. 31 The PICA3/GEM code 31 employs the Generalized
Evaporation Model32 and the Rutherford Appleton Laboratory(RAL) model38 to describe the competition between particle
evaporation and fission. The predicted fission yields at intermediate energies strongly depend not only on the fission
models, but also on quality of the models for the cascade and
197Au This work

103

209Bi This work
197Au PICA3/GEM [31]Yields / µ b eq.q.-1

209Bi PICA3/GEM [31]

102

101

30

50

70

90

110

130

150

A

Figure 10. Mass yield curves of the photofission of 197Au and 209Bi at
E 0 = 1000 MeV. The date for 197 Au and 209 Bi are shown by open
circles connected by a solid curve and by open squares connected by adashed curve, respectively. The results of the PICA3/GEM calculations31 are plotted by closed circles and closed squares for 197Au and209
Bi, respectively. (From References 26 and 34)

preequilibrium steps that precede fission and the particle evaporation. The fission is regarded as a collective process of thenucleus. After the emission of a few fast particles, the residual
nucleus attains an equilibrated state, where fission competes
with the particle evaporation. A large number of intermediate
nuclei each with its own fission characteristics are formed.
Therefore, small deviations in the cascade step may lead to avery different population of the intermediate nucleus, which
contributes differently to the mass yield distribution.
5. Summary
The recoil properties of 137 radionuclides formed in thephotospallation reactions of 27Al, natV, natCu, 93Nb, natAg, natTa,
and 197Au, induced by bremsstrahlung of end-point energies of
E 0 = 600–1100 MeV, have been investigated by the thicktarget thick-catcher method. Reflecting the resonance character in photonuclear reactions, the mean ranges in the forward
and backward directions are E 0 -independent at the studied
energies and exhibit two components of the (γ, xnyp) (x, y ≥ 1)
and the (γ, xn) (x ≥ 1) reactions. The forward-to-backward
ratios F/B were found to be independent of the mass difference∆A between a product (Ap) and a target (At ) and also of At . The
kinematic properties of the product nuclei were analyzed by
the two-step vector velocity model. The forward velocity v
after the first step of photon reaction is quite different fromthat of proton reaction at Ep ≤ 3 GeV, though the difference
disappears at higher energies. On the other hand, the mean
kinetic energy T of the residual nucleus in the second step isalmost equal to that of proton reaction irrespective of Ep. The
PICA3/GEM code at E 0 = 600–1100 MeV reproduces theexperimental results of natV, natCu, 93Nb, and natAg fairly well,
but the same calculation for heavier targets gives T values
lower than the experimental results, indicating some nuclearstructure effect such as a medium effect notably at At ≥ 100.
The average kinetic energy of the emitted particles in arandom-walk process of both the photon and proton reactions,
εs = T/(∆A/At ), was found to increase along with an increase of
At and to become constant above At = 100. The εs values ofphoton reaction appear to be slightly lower than those of
proton reactions for natAg, natTa, and 197Au. This difference
may indicate the lower excitation energy left after the first stepin photon reactions than that in proton reactions, which is notapparent in T.
The recoil properties and yields of radionuclides formed in
the photofission of 197 Au and 209 Bi were obtained at E 0 =300–1100 MeV using the catcher foil technique with the aid ofintensive chemical separation. Both the F/B and T values ofthe fission products of 197Au were clearly distinguished fromthose of the photospallation products. The variation of F/B
and T/EC for 24Na produced from 27Al, natV, natCu, natAg, and197
Au showed a change in the production mechanism fromspallation to fragmentation with respect to At . The charge- andmass-distributions of the photofission of 197Au and 209Bi weresuccessfully deduced based on the 58 and 63 fission yields,
respectively. The charge distribution was reproduced by aGaussian function with the most probable charge Zp expressedby a linear function of the product mass number A, i.e., Zp =RA + S, and with the A-independent width FWHM CD . The
charge distribution parameters R, S, and FWHMCD were foundto be independent of E0 above 600 MeV, reflecting the resonance nature in photonuclear reactions at intermediate energies. The numbers of pre- and post-fission neutrons werededuced to be vpre = 11±1 and vpost = 1.7±0.3 for 197Au, and to
be v pre = 12±1 and v post = 1.4±0.3 for 209 Bi, assuming theunchanged charge distribution hypothesis. Based on the
charge distribution parameters, the symmetric mass yield
distribution with the most probable mass Ap of 92 m.u. and thewidth FWHMMD of 39 m.u. was obtained for 197Au at E0 ≥ 600

Recoil Studies of Photonuclear Reactions
209

MeV. The Ap value for Bi was larger by 4 m.u. than that for197
Au and the FWHMMD was smaller by 6 m.u. The comparisons of the charge- and mass-distribution parameters with thelatest calculations using the PICA3/GEM code indicated some
defects in the nuclear and reaction models on which the code
was based.
Acknowledgement. The main part of the present study wasdone while the author belonged to Radiochemistry Laboratory,
Department of Chemistry, Faculty of Science, Kanazawa
University. The author would like to express his gratitude toProf. K. Sakamoto of Department of Chemistry, Faculty of
Science, Kanazawa University, Prof. I. Fujiwara of
Department of Economics, Faculty of Economics, OtemonGakuin University, Prof. S. Shibata of Research Reactor
Institute, Kyoto University, Prof. M. Furukawa of Faculty ofEnvironmental and Information Sciences, Yokkaichi
University, and Dr. Oura of Department of Chemistry,
Graduate School of Science, Tokyo Metropolitan University,
for their guidances and advices throughout the course of thiswork. The students of the Radiochemistry Laboratory ofKanazawa University are thanked for their cooperation inradiochemical separations and radioactivity measurements.
The author would like to acknowledge Prof. K. Masumoto andthe ES crew members of the High Energy Accelerator
Research Organization at Tanashi for their invaluable cooperations in the course of experiments.
References(1) K. Sakamoto, M. Yoshida, Y. Kubota, T. Fukasawa, A.
Kunugise, Y. Hamajima, S. Shibata, and I. Fujiwara, Nucl.
Phys. A 501, 693 (1989).
(2) K. Sakamoto, Y. Hamajima, M. Soto, Y. Kubota, M.
Yoshida, A. Kunugise, M. Masatani, S. Shibata, M.
Imamura, M. Furukawa, and I. Fujiwara, Phys. Rev. C 42,
1545 (1990).
(3) Y. Oura, A. Yazawa, M. Yoshida, S. R. Sarkar, K.
Sakamoto, S. Shibata, I. Fujiwara, and M. Furukawa,Radiochim. Acta 68, 27 (1995).
(4) K. Sakamoto, S. R. Sarkar, Y. Oura, H. Haba, H.
Matsumura, Y. Miyamoto, S. Shibata, M. Furukawa, andI. Fujiwara, Phys. Rev. C 59, 1497 (1999).
(5) S. Shibata, M. Imamura, T. Miyachi, M. Mutou, K.
Sakamoto, Y. Hamajima, M. Soto, Y. Kubota, M.
Yoshida, and I. Fujiwara, Phys. Rev. C 35, 254 (1987).
(6) S. R. Sarkar, M. Soto, Y. Kubota, M. Yoshida, T.
Fukasawa, K. Matsumoto, K. Kawaguchi, K. Sakamoto,S. Shibata, M. Furukawa, and I. Fujiwara, Radiochim.
Acta 55, 113 (1991).
(7) S. R. Sarkar, Y. Kubota, T. Fukasawa, K. Kawaguchi, K.
Sakamoto, S. Shibata, and I. Fujiwara, Radiochim. Acta
55, 139 (1991).
(8) S. R. Sarkar, Y. Oura, K. Kawaguchi, A. Yazawa, K.
Sakamoto, S. Shibata, and I. Fujiwara, Radiochim. Acta62, 7 (1993).
(9) S. Shibata, M. Imamura, K. Sakamoto, S. Okizaki, S.
Shibutani, H. Matsumura, M. Furukawa, I. Fujiwara, H.
Nagai, and K. Kobayashi, Radiochim. Acta 80, 181(1998).
(10) H. Matsumura, K. Washiyama, H. Haba, Y. Miyamoto, Y.
Oura, K. Sakamoto, S. Shibata, M. Furukawa, I. Fujiwara,
H. Nagai, T. Kobayashi, and K. Kobayashi, Radiochim.
Acta 88, 313 (2000).
(11) B. G. Harvey, Annu. Rev. Nucl. Sci. 10, 235 (1960).
(12) J. M. Alexander, Nuclear Chemistry, edited by L. Yaffe(Academic, New York 1968), Vol. I, p. 273.
(13) L. Winsberg, Phys. Rev. C 22, 2116 (1980)and C 22, 2123
(1980).

J. Nucl. Radiochem. Sci., Vol. 3, No. 2, 2002 A19(14) A. Järund and B. Forkman, Z. Physik A 281, 47 (1977).
(15) A. A. Arakelyan, A. R. Balabekyan, A. S. Danagulyan,
and A. G. Khudaverdyan, Nucl. Phys. A 534, 535 (1991).
(16) K. A. Amroyan, S. A. Barsegyan, and N. A. Demekhina,
Phys. At. Nucl. 56, 6 (1993).
(17) K. A. Amroyan, S. A. Barsegyan, and N. A. Demekhina,
Phys. At. Nucl. 56, 712 (1993).
(18) H. Haba, H. Matsumura, Y. Miyamoto, K. Sakamoto, Y.
Oura, S. Shibata, M. Furukawa, and I. Fujiwara, J.
Radioanal. Nucl. Chem. 239, 133 (1999).
(19) I. Fujiwara, H. Haba, H. Matsumura, Y. Miyamoto, K.
Sakamoto, Y. Oura, S. Shibata, and M. Furukawa, Czech.
J. Phys. 49, 831 (1999).
(20) H. Haba, H. Matsumura, K. Sakamoto, Y. Oura, S.
Shibata, M. Furukawa, and I. Fujiwara, Radiochim. Acta85, 1 (1999).
(21) H. Haba, H. Matsumura, K. Sakamoto, Y. Oura, S.
Shibata, M. Furukawa, and I. Fujiwara, Radiochim. Acta88, 375 (2000).
(22) M. C. Duijvestijn, A. J. Koning, J. P. M. Beijers, A.
Ferrari, M. Gastal, J. van Klinken, and R. W. Ostendorf,
Phys. Rev. C 59, 776 (1999).
(23) R. E. Prael and H. Lichtenstein, Los Alamos National
Laboratory Report No. LA-UR-89-3014 (1989).
(24) H. Haba, M. Igarashi, K. Washiyama, H. Matsumura, M.
Yamashita, K. Sakamoto, Y. Oura, S. Shibata, M.
Furukawa, and I. Fujiwara, J. Nucl. Radiochem. Sci. 1, 53(2000).
(25) H. Haba, M. Igarashi, K. Washiyama, H. Matsumura, M.
Yamashita, K. Sakamoto, Y. Oura, S. Shibata, M.
Furukawa, and I. Fujiwara, J. Nucl. Radiochem. Sci. 1, 69(2000).
(26) H. Haba, M. Kasaoka, M. Igarashi, K. Washiyama, H.
Matsumura, Y. Oura, S. Shibata, K. Sakamoto, M.
Furukawa, and I. Fujiwara, Radiochim. Acta 90, 371(2002).
(27) T. A. Gabriel and R. G. Alsmiller, Jr., Phys. Rev. 182,
1035 (1969).
(28) T. A. Gabriel, M. P. Guthrie, and O. W. Hermann, Oak
Ridge National Laboratory Report No. ORNL-4687(1971).
(29) C. Y. Fu, PICA95, An Intra-Nuclear Cascade Code for
25-MeV to 3.5-GeV Photon-Induced Nuclear Reactions,presented at SATIF-3, Sendai, May 12-13, 1997.
(30) T. Sato, K. Shin, S. Ban, Y. Namito, H. Nakamura, and H.
Hirayama, Nucl. Instr. Meth. A 437, 471 (1999).
(31) T. Sato, K. Shin, S. Ban, T. A. Gabriel, C. Y. Fu, and H.
S. Lee, Proc. of Advanced Monte Carlo on Radiation
Physics, Particle Transport Simulation and Applications,
Lisbon, Oct. 23-26, 2000 (private communication).
(32) S. Furihata, Nucl. Instr. Meth. B 171, 251 (2000).
(33) H. Haba, K. Sakamoto, H. Matsumura, Y. Oura, S.
Shibata, M. Furukawa, and I. Fujiwara, Czech. J. Phys. (inpress).
(34) H. Haba, K. Sakamoto, M. Igarashi, M. Kasaoka, K.
Washiyama, H. Matsumura, Y. Oura, S. Shibata, M.
Furukawa, and I. Fujiwara, Czech. J. Phys. (in press).
(35) K. Osada, T. Fukasawa, K. Kobayashi, Y. Hamajima, K.
Sakamoto, S. Shibata, and I. Fujiwara, Res. Rept. Lab.
Nucl. Sci. Tohoku Univ. 20, 299 (1987).
(36) H. Haba, Ph. D. Thesis (Kanazawa Univ. 1999).
(37) H. W. Bertini, Phys. Rev. 131, 1801 (1963).
(38) F. Atchison, Kernforschungsanlage Jülich GmbH Report
No. Jül-Conf-34 (1980).
(39) G. Rudstam, Z. Naturforsch. 21a, 1027 (1966).
(40) L. Winsberg, Nucl. Instr. Meth. 150, 465 (1978).
(41) J. F. Ziegler, J. P. Biersack, and U. Littmark, The Stopping
and Range of Ions in Solid (Pergamon, New York, 1985).
(42) M. Lagarde-Simonoff, S. Regnier, H. Sauvageon, and G.

A20 J. Nucl. Radiochem. Sci., Vol. 3, No. 2, 2002
N. Simonoff, Nucl. Phys. A 260, 369 (1976).
(43) V. P. Crespo, J. M. Alexander, and E. K. Hyde, Phys. Rev.
131, 1765 (1963).
(44) N. T. Porile and S. Tanaka, Phys. Rev. 135, B122 (1964).
(45) J. C. Cumming, P. E. Haustein, and H. -C. Hseuh, Phys.
Rev. C 18, 1372 (1978).
(46) J. B. Cumming, P. E. Haustein, and H. -C. Hseuh, Phys.
Rev. C 24, 2162 (1981).
(47) G. D. Cole and N. T. Porile, Phys. Rev. C 25, 244 (1982).
(48) S. C. Fung and I. Perlman, Phys. Rev. 87, 623 (1952).
(49) R. Wolfgang and G. Friedlander, Phys. Rev. 94, 775(1954).
(50) V. L. Volkova and F. P. Denisov, Sov. Phys. JETP 8, 372(1959).
(51) A. M. Poskanzer, J. B. Cumming, and R. Wolfgang, Phys.
Rev. 129, 374 (1963).
(52) B. Neidhart and K. Bächmann, J. Inorg. Nucl. Chem. 34,

Haba
423 (1972).
(53) J. B. Cumming and K. Bächmann, Phys. Rev. C 6, 1362
(1972).
(54) E. P. Steinberg and L. Winsberg, Phys. Rev. C 10, 1925
(1974).
(55) S. B. Kaufman, E. P. Steinberg, and M. W. Weisfield,
Phys. Rev. C 18, 1349 (1978).
(56) C. F. Wang, G. D. Cole, and N. T. Porile, Phys. Rev. C
29, 569 (1984).
(57) C. F. Wang and N. T. Porile, Nucl. Phys. A 468, 711(1987).
(58) E. Ross and K. Bächmann, Radiochim. Acta, 21, 13(1974).
(59) A. P. Komar, B. A. Bochagov, A. A. Kotov, Yu. N.
Ranyuk, G. G. Semenchuk, G. E. Solyakin, and P. V.
Sorokin, Sov. J. Nucl. Phys. 10, 30 (1970).