Neutron cross-section data evaluation for 181Ta up to 150 MeV

NIM B Beam Interactions with Materials & Atoms

Nuclear Instruments and Methods in Physics Research B 248 (2006) 225–241 www.elsevier.com/locate/nimb

Neutron cross-section data evaluation for

181

Ta up to 150 MeV

Pavel Pereslavtsev *, Ulrich Fischer Association FZK-Euratom, Forschungszentrum Karlsruhe, Institut fuer Reaktorsicherheit, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany Received 7 February 2006; received in revised form 22 March 2006 Available online 22 June 2006

Abstract A complete data evaluation of nuclear cross-sections for general purpose applications was performed for the reaction system n + 181Ta up to 150 MeV neutron incident energy. Use was made of the nuclear model codes ECIS96 for optical model calculations and GNASH for nuclear reaction cross-section calculations including the multiple pre-equilibrium emission of the particles. High energy experimental data were taken into account for evaluating the total cross-section. Global optical model potentials were used for neutrons, protons, deuterons and a-particles. Optical model potentials for tritons and He-3 were constructed on the basis of proton and neutron potentials. To improve the neutron emission spectra, collective excitations were included in the GNASH calculations. Double-differential cross-sections of the emitted particles were calculated on the basis of the Kalbach systematics. A complete general purpose data file in ENDF-6 format was finally prepared covering the entire energy range from thermal energies up to 150 MeV. The newly evaluated data are in good agreement with measurements of 181Ta cross-sections and particle emission spectra. The ENDF data file is suitable for a broad range of applications including fission and fusion technology and accelerator driven systems.  2006 Elsevier B.V. All rights reserved. PACS: 24.10.Eq; 24.10.Ht; 24.30.Cz; 24.60.Dr; 25.40.Dn; 25.40.Fq Keywords: Tantalum; High energies; Neutrons; Cross-sections; Evaluated data file

1. Introduction The majority of the existing general purpose data evaluations for neutron transport calculations cover the energy range up to 20 MeV. During the last decade extensive efforts were devoted to the elaboration of high energy data evaluations both for incident neutrons and protons [1–7]. The maximum projectile incident energy varies from 50 to 200 MeV. This work is devoted to the evaluation of neutron cross-section data for 181Ta up to 150 MeV. Ta is of importance both for nuclear fusion and fission applications. It is a major constituent of the low activation ferritic–martensitic steel Eurofer which is planned to be qualified for future fusion reactors by means of test irradiations in the IFMIF (International Fusion Irradiation *

Corresponding author. Tel.: +49 7247 824365; fax: +49 7247 823718. E-mail address: [email protected] (P. Pereslavtsev).

0168-583X/$ - see front matter  2006 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2006.04.150

Facility) neutron source with a neutron spectrum extending up to 55 MeV. For accelerator driven systems (ADS), tantalum is a candidate material of the spallation target. Thus there is a need to have available for these applications reliable data evaluations above 20 MeV. As a starting point for the high energy data evaluations it is in general assumed that the low energy neutron data (below 20 MeV) available in the international nuclear data libraries are adequately good for applications in fission and fusion technology. This decreases significantly the effort for new evaluations because the data above 20 MeV are considered to be an extension of the low energy data. The proper choice of the low energy evaluation is guided by comparisons with available experimental data, benchmark analyses and, to some extent, by the envisaged application of the evaluated data (fission, fusion or some experimental facility). There are in general two approaches for combining the low and high energy data. The first one is to prepare

226

P. Pereslavtsev, U. Fischer / Nucl. Instr. and Meth. in Phys. Res. B 248 (2006) 225–241

evaluated data from 20 to 150 or 200 MeV independent from the chosen low energy data and then store both the low and high energy parts in one single data file [2,3]. This may result in inconsistencies and discontinuous data at 20 MeV. The second one is to adjust in some way both parts at 20 MeV [1,4,7]. This requires some efforts in adjusting the cross-sections for the main reaction channels and maintaining a minimum consistency. Recently a few new high energy neutron data evaluations were issued following a new approach [5,6]. The main idea is to perform nuclear model calculations and evaluations over the entire energy range from very low energies up to the upper energy limit making use of the same computer codes. The obvious advantage of this method is the consistency of the evaluated data. The only remaining problem is the resonance structure of the low energy data such as the total and the elastic scattering cross-sections. The practice here is to adapt these cross-section data from existing data evaluations and apply modifications if required and possible. Another important issue is the completeness of the evaluated data file for transport calculations to ensure it can be used in different applications. The existing neutron data evaluations below 20 MeV in general do not take into account all relevant reaction channels since they were supposed to be used for nuclear fission applications. Neutron induced reactions such as (n, 2na), (n, t), (n, d), (n, 3He), (n, p2n) were considered not important enough to be included in the data evaluations. The cross-sections for these reactions are in general small compared to the dominant reactions in the relevant energy range such as (n, 2n), (n, 3n), etc. The availability of minor reaction channels in the data evaluations makes them suitable for a broader area of applications. Reaction cross-section data should be provided on the evaluated data file for all kinematically allowed reaction types. In view of the variety of open reaction channels

above 20 MeV incident energy this is unfeasible in the given ENDF format. In addition, such detailed data for hundreds of reaction channels are not necessary for particle transport applications. There is required, however, the availability of the secondary particle emission spectra (energy–angle distributions) on the data files. ENDF format rules offer the option to use lumped cross-sections for reactions with a neutron in the entrance channel and any kind of particle in the exit channel (neutron in, anything out). The use of the lumped reaction type MT = 5 is most suitable for storing multiple particle emission reaction cross-section data in the high energy range. For each specified secondary particle type the corresponding particle yields and the associated energy–angle distributions are stored. Hence the energy–angle distributions are available on the data file for any kind of emitted particles. Accordingly, the MT = 5 format option is used in this evaluation for storing the high energy data while the individual reaction channels are represented in the traditional way below 20 MeV. Whenever available, evaluated neutron cross-sections and experimental data are used for comparing and crosschecking the newly evaluated 181Ta high energy data. Below 20 MeV, the evaluated data are compared to those from the ENDF/B-VI and JENDL-3.3 general purpose data libraries and the JEFF-3.0/A activation file [8]. 2. Evaluation procedure The evaluation procedure is outlined in Fig. 1. The evaluation starts with optical model calculations which form the basis for all subsequent nuclear model calculations. The code ECIS96 [9] is applied to generate transmission coefficients for further statistical model calculations and for calculating the total, reaction, elastic and inelastic scattering cross-sections. The GNASH code [10] is used

OPTICAL MODEL CALCULATIONS

NUCLEAR REACTION CS CALCULATIONS

GNASH

ECIS96

Angular distributions

- elastic

Cross sections

- total, elastic,

scattering

reaction

- inelastic

- direct

Transmission Coefficients

Individual reaction cross sections

processing

ENDF-6 formatted file Fig. 1. Flowchart of the evaluation procedure.

Particle emission spectra

P. Pereslavtsev, U. Fischer / Nucl. Instr. and Meth. in Phys. Res. B 248 (2006) 225–241

for calculating individual reaction cross-sections and secondary particle emission spectra. It includes nuclear models for the multiple emission of secondary particles through statistical (Hauser–Feshbach) and pre-equilibrium processes. Both codes are linked through a processing system that enables the production of separate ENDF-6 formatted data files. This approach is applied for the entire energy range of incident neutrons considered, i.e. from 0.001 to 150 MeV. 3. Optical model calculations The choice of the proper optical model potential (OMP) is fundamental for the evaluation of nuclear cross-section data. Suitable OMP must be available for all particles in the entrance and exit channels, i.e. neutrons, protons, deuterons, tritons, 3He and a-particles. Because the evaluation covers neutron incident energies from 0.001 to 150 MeV the OMP should also be applicable for the entire energy range to avoid any discontinuity of the nuclear cross-section data. It need also be taken into account that 181Ta is a deformed nucleus. The optical model potentials used for this evaluation are listed in Table 1. The most suitable and well approved

Table 1 Optical model potentials used for this evaluation Particle

References

Energy range (MeV)

Neutron Proton Deuteron Triton 3 He a

[11] [11] [13] [15] [15] [14]

0.001–200 0.001–200 20–100 10–50 10–50 1–150

OMPs for neutrons and protons are the relativistic global optical potentials of Koning and Delaroche. Although no data for deformed nuclei were considered in elaborating these OMPs, they were declared to be applicable for deformed nuclei as well. Actually our analyses proved a higher accuracy of the Koning and Delaroche OMP as compared to the deformed OMP of Young et al. [12] which was developed for the neighboring tungsten isotopes, see details below. For this reason the Koning and Delaroche OMP was adopted in this evaluation for neutrons and protons without any adjustments. For deuterons the global OMP of Bojowald et al. [13] was applied with the extension of the upper energy limit to 150 MeV. The global OMP of Avrigeanu and Hodgson [14] was used for a-particles up to 150 MeV. For tritons and 3He the OMP of Beccheti and Greenlees [15] was adopted. The upper energy limit for these potentials is 50 MeV. To overcome this problem we applied for these particles as well a simplified folding approach [16–18]. The OMPs produced in this approach are based on the proper combination of the neutron and proton potentials. For this purpose we used again the OMPs of Koning and Delaroche. The details of the data evaluation for these particles are discussed later. An automated procedure was elaborated to generate the transmission coefficients for the required energy mesh for all particles mentioned; the optical model potential used in this procedure can be easily changed. 3.1. Total, reaction, elastic scattering cross-sections The total cross-section serves as indicator of the quality of the evaluated data and applicability of the OMP. Furthermore, it is directly used in neutron transport calculations as well as the elastic scattering cross-section. Figs. 2

10 181

n+ Ta Total

9

Cross section [barn]

8 7 6 Finlay, 93 Poenitz, 81 Tsubone, 84 Byoun, 73 Poenitz, 83 Foster, 71 ENDF/B-VI Koning Young this evaluation

5 4 3 2 -1

10

227

0

10

1

10

2

10

Neutron energy [MeV] Fig. 2. Evaluated total cross-section compared with measurements [19–24].

228

P. Pereslavtsev, U. Fischer / Nucl. Instr. and Meth. in Phys. Res. B 248 (2006) 225–241 10 181

Hudson, 62 Cox, 72 Gilboy, 63 Holmqvist, 69 Walt, 55 Walt, 54 Nikolenko, 85 Kazakova, 65 ENDF/B-VI JENDL-3.3 Koning Young this evaluation

n+ Ta Elastic scattering

Cross section [barn]

8

6

4

2

0 -1

10

0

1

10

10

2

10

Neutron energy [MeV] Fig. 3. Evaluated elastic scattering cross-section. Experimental data [25–32] are shown.

and 3 show the evaluated total and elastic scattering cross-sections, respectively. The results of the optical model calculations with the Young OMP are included for comparison. The data obtained with Koning OMP describe very well the experimental results above 3 MeV and especially at high energies. It fails, however, to fit the experimental data at lower energies. This is probably due to the exclusion of data for deformed nuclei in elaborating the OMP. It is noted that the ENDF/B-VI data evaluation shows a severe disagreement with the measured data at low energies. Our evaluation is based on optical model calculations using the Koning and Delaroche OMP above 3 MeV and on the fit of the experimental data below. The slightly overestimated total cross-section between 1 and 3 MeV results from rather high inelastic scattering cross-sections in this region. The difference between evaluated and measured data of the elastic scattering cross-section is about 2 b at 0.5 MeV, Fig. 3. This difference cannot be explained by an overestimated total inelastic scattering cross-section because its value is less than 2 b at this energy point and the evaluation describes very well the measured values, Fig. 4. Another channel relevant in this energy region is the (n, c) reaction. The evaluated (n, c) cross-section also fits very well experimental data (see below) and thus cannot be the reason for the underestimated elastic scattering cross-section.

energies: 0.13 for the first excited state 9/2+ and 0.1, 0.1, 0.1, 0.02, 0.01, 0.01 for the following excited states, respectively. The equilibrium parts of the cross-sections leading to excited states of the nucleus were calculated with GNASH. Fig. 4 shows the results of the evaluation for a few selected excited levels and the total inelastic scattering cross-section (i.e. sum over all excited levels and continuum inelastic scattering). The total inelastic scattering crosssection is given in all data evaluations explicitly. While ENDF/B-VI and JENDL-3.3 include cross-sections for 10 and 14 excited levels, respectively, our evaluation provides cross-sections for 20 excited levels. The main contributors to the total inelastic scattering cross-section are the first several levels. The evaluated data are even lower than some experimental results. Therefore a possible overestimation of the total inelastic scattering cross-section cannot be the reason of the underestimated elastic scattering crosssection below 1 MeV. For the coupled channels mentioned above the effect of direct reactions is significant, Fig. 4. Both ENDF/B-VI and JENDL-3.3 evaluations are well below our evaluation at energies above several MeV. As a result, these evaluations show severe deficiencies in the high energy tail of the neutron emission spectra. The level scheme used in ENDF/B-VI is definitely not sufficient and the total inelastic scattering cross-section around 1 MeV is greatly overestimated.

3.2. Inelastic scattering cross-sections

3.3. Elastic scattering angular distributions

Direct reactions to discrete states were calculated with ECIS96 making use of the already mentioned neutron OMP. We considered the following levels for coupledchannels calculations: 7/2+ (ground state), 9/2+, 11/2+, 13/2+, 15/2+, 17/2+, 19/2+, 21/2+. The deformation parameters were chosen to fit the high energy tails of the secondary neutron emission spectra for different incident

The angular distributions for elastically scattered neutron were checked over the entire energy range up to 150 MeV. A few results are displayed in Fig. 5. Note again the severe disagreement of the ENDF/B-VI data evaluation experimental data at lower energies. The experimental data available for 181Ta cover incident energies only up to 15 MeV. To check the appli-

P. Pereslavtsev, U. Fischer / Nucl. Instr. and Meth. in Phys. Res. B 248 (2006) 225–241 1000

1800 181

181

181

+

Ta(n,n') Ta(9/2 ) Elevel=0.1363 MeV

1600

181

-

Ta(n,n') Ta(9/2 ) Elevel=0.15855 MeV

900 800

1400

700

1200

Cross section [mb]

Cross section [mb]

229

Glazkov, 64 Rogers, 61 Rogers, 71 ENDF/B-VI JENDL-3.3 this evaluation

1000 800 600

Rogers, 71 Broder, 69 ENDF/B-VI JENDL-3.3 this evaluation

600 500 400 300

400

200

200

100 0

0 0

2

4

6

8

0

10

2

4

6

8

10

Neutron energy [MeV]

Neutron energy [MeV] 180

600 181

181

181

+

Ta(n,n') Ta(11/2 ) Elevel=0.3016 MeV

500

181

+

Ta(n,n') Ta(13/2 ) Elevel=0.4952 MeV

160

400

Cross section [mb]

Cross section [mb]

140

Rogers, 71 Rogers, 61 Glazkov, 64 ENDF/B-VI JENDL-3.3 this evaluation

300

200

120

Rogers, 71 ENDF/B-VI JENDL-3.3 this evaluation

100 80 60 40

100

20 0

0 0

2

4

6

8

0

10

2

4

6

8

10

Neutron energy [MeV]

Neutron energy [MeV] 50 181

+

Cross section [mb]

40

Cross section [mb]

181

Ta(n,n') Ta(15/2 ) Elevel=0.71667 MeV

30

20

Rogers, 71 JENDL-3.3 this evaluation

10

0 0

2

4

6

8

10

Neutron energy [MeV]

Neutron energy [MeV]

Fig. 4. Evaluated inelastic scattering cross-sections for the 9/2+, 9/2 , 11/2+, 13/2+, 15/2+ excited levels and the total inelastic scattering cross-section. Experimental data [29,30,33–39].

cability of the Koning and Delaroche OMP at higher energies we performed comparisons of proton elastic scattering angular distributions to experimental data available for 181Ta up to 146 MeV. We applied both the Koning and Delaroche and the Young proton OMPs, Fig. 6. At high energies and angles greater than 20

there is an overestimation of the differential cross-section calculated with Young OMP. This is also observed for 150 MeV neutrons as shown in Fig. 5. Thus we may conclude that the Koning and Delaroche OMP potential gives better agreement with experimental data from 3 to 150 MeV neutron incident energies. Above 3 MeV

230

P. Pereslavtsev, U. Fischer / Nucl. Instr. and Meth. in Phys. Res. B 248 (2006) 225–241 4

10

Elastic scattering En= 1 MeV

3

Elastic scattering En= 7 MeV

10

Beyster, 56 Smith, 05 this evaluation Young

3

dσ/dΩ [mb/sr]

dσ/dΩ [mb/sr]

10

Walt, 54 Darden, 55 Smith, 05 ENDF/B-VI JENDL-3.3= this evaluation Koning Young

2

10

2

10

1

10

1

10

0

20

40

60

80

100

120

140

160

180

0

20

40

60

Θc.m. [deg]

80

100

120

140

160

180

Θc.m. [deg] 5

10

Elastic scattering En= 15 MeV

4

10

Elastic scattering En= 150 MeV

4

10

3

10

Hansen, 85 Benenson, 73 Cross, 60 Hudson, 62 ENDF/B-VI JENDL-3.3 this evaluation

dσ/dΩ [mb/sr]

2

10

2

10

this evaluation Young

1

10

dσ/dΩ [mb/sr]

3

10

0

10

-1

10

-2

10

-3

10

-4

10

1

10

-5

10

-6

10 0

-7

10

10

0

20

40

60

80

100

120

140

160

180

0

20

40

60

Θc.m. [deg]

80

100

120

140

160

180

Θc.m. [deg]

Fig. 5. Evaluated n + 181Ta elastic scattering angular distributions for 1, 7, 15 and 150 MeV incident neutron energies. Experimental data [25,30,39–44] are shown.

8

6

10

10

7

Elastic scattering Ep= 95 MeV

5

10

4

10

6

10

5

10

4

3

10

10

Gerstein, 57 Young Koning

10

1

Steinberg, 64 Young Koning

3

10

dσ/dΩ [mb/sr]

2

dσ/dΩ [mb/sr]

Elastic scattering Ep= 146 MeV

10

10

0

10

-1

10

-2

2

10

1

10

0

10

-1

10

-2

10

-3

10

10

-4

10

-3

10

-5

10

-4

10

-6

10

-7

-5

10

10

0

20

40

60

80

100

120

140

160

180

Θc.m. [deg]

0

20

40

60

80

100

120

140

160

180

Θc.m. [deg]

Fig. 6. p + 181Ta differential elastic scattering cross-section. Results based on the Young Koning OMPs are compared with experimental data [45,46].

the present evaluation is based on Koning OMP and below 3 MeV JENDL-3.3 data for the elastic scattering angular distributions were used because they fit rather well experimental results.

3.4. Inelastic scattering angular distributions The experimental data base for n + 181Ta inelastic scattering angular distributions is very small. There are a few

P. Pereslavtsev, U. Fischer / Nucl. Instr. and Meth. in Phys. Res. B 248 (2006) 225–241

231

2

181

181

10

+

Ta(n,n') Ta(9/2 ) En= 1 MeV

181

181

+

Ta(n,n') Ta(11/2 ) En= 1 MeV

2

dσ/dΩ [mb/sr]

dσ/dΩ [mb/sr]

10

Rogers, 61 this evaluation

Rogers, 61 this evaluation 1

0

20

40

60

80

100

120

140

160

180

Θc.m. [deg]

10

0

20

40

60

80

100

120

140

160

180

Θc.m. [deg] +

+

Fig. 7. Evaluated differential inelastic scattering for 9/2 and 11/2 levels and incident neutron energy 1 MeV. Experimental data [35] are shown.

measurements below 1 MeV by Rogers et al. [35]. Fig. 7 shows the evaluated inelastic scattering angular distributions for 1 MeV neutrons. For both levels the evaluation underestimates the experimental results. However, the evaluated cross-sections for these levels are very close to the later measurements by Rogers et al. [36], Fig. 4. Supposing that the earlier measurements were overestimated by factors 1.5 and 1.25 for the 9/2+ and 11/2+ levels, respectively, we can deduce that the evaluated data fit well the corrected experimental results. 4. Nuclear reaction cross-section calculations Nuclear reaction cross-sections and particle emission spectra were calculated with the GNASH code. This code has been extensively used for nuclear data evaluations over the past three decades. The physics models of GNASH, its advantages and drawbacks were discussed in various publications [2,3,10,47,48]. GNASH utilizes the Hauser–Feshbach model for multiple particle emissions through statistical processes, the exciton model of Kalbach [49] for single particle and the model of Chadwick et al. [50] for multiple particle pre-equilibrium reactions. For compound nuclear reactions we used the Ignatyuk form of the Fermi-gas model with energy-dependent level density parameters [51]. Gamma-ray transmission coefficients were calculated using the Kopecky and Uhl model [52]. In the pre-equilibrium model used in GNASH the excitation of the collective states with different multi-polarities is not considered. It was reported [6,53,54] that for inelastically scattered particles these collective states are responsible for the well known humps in the high energy tails of the energy emission spectra. To account for this effect we applied the model developed by Kalbach [53]. We considered the excitation of the giant resonances with four different multi-polarities: low energy octupole (LEOR) with 3 collective state, 2+ giant quadrupole (GQR), 0+ giant monopole (GMR) and 3 high energy octupole (HEOR)

resonances. The position of the maximum, the width and the deformation parameter of the resonances are calculated within this model. The cross-section for each resonance was calculated with ECIS96 at all neutron incident energies and then broadened assuming a Gaussian distribution. This procedure was automated and the data generated for all collective excitations in the desired incident energy mesh were read in GNASH. There are two additional data sets that must be present for GNASH calculations: the level structure file for all nuclides involved in the calculations and a comprehensive table for nuclide masses, ground state spins and parities. For the level structure data we use the Reference Input Parameter Library RIPL-2 [55]. In some cases where the RIPL-2 data are not sufficient or the level structure is not present, we used reference data from the table of isotopes [56]. The second set of data (mass table) is distributed with the GNASH package and based on the Wapstra table [10]. We essentially modified these data making use of the available information [56]. Since the evaluation covers incident neutron energies up to 150 MeV we took into account in the calculations as many as possible reaction paths. The number of residual nuclides considered was however limited by a maximum charge difference of DZ = 5 and a maximum mass difference of DA = 20 with respect to the target nucleus 181Ta. 4.1. Exclusive nuclear reactions The term exclusive is applied for nuclear reactions with explicit specifications of the types and number of outgoing particles, for instance (n, 2n), (n, a), (n, np) reactions. In our evaluation we considered (n, 2n), (n, 3n), (n, p), (n, d), (n, t), (n, 3He), (n, a), (n, np), (n, na), (n, 2na), (n, 2np) and (n, c) reactions. Data for these reactions were included in the low energy part of the evaluated file. Above 20 MeV these cross-sections were assigned zero on the file since they are included in the lumped MT = 5 reaction type. Examples

232

P. Pereslavtsev, U. Fischer / Nucl. Instr. and Meth. in Phys. Res. B 248 (2006) 225–241 2000

2500 181

181

180

179

Ta(n,3n) Ta

Ta(n,2n) Ta Veeser, 77 Frehaut, 80 Takahashi, 89 ENDF/B-VI JENDL-3.3 JEFF-3.0/A this evaluation

1500

1500

Cross section [mb]

Cross section [mb]

2000

1000

1000

Veeser, 77 ENDF/B-VI JENDL-3.3 JEFF-3.0/A this evaluation

500

500

0

0 6

8

10

12

14

16

18

20

22

24

26

28

14

30

16

18

20

22

24

26

28

30

Neutron energy [MeV]

Cross section [mb]

Cross section [mb]

Neutron energy [MeV]

Neutron energy [MeV]

Neutron energy [MeV] 4

1

10

10

181

179

181

182

Ta(n,γ) Ta

Ta(n,t) Hf

0 3

10

-1

10

Cross section [mb]

Cross section [mb]

10

Woelfle, 90 systematics JEFF-3.0/A GNASH (fold) GNASH (Beccheti) this evaluation

-2

10

-3

10

2

10

Necheva, 94 Xu, 88 Wagner, 80 Lepine, 72 Budnar, 79 Miskel, 62 Kononov, 77 Bokhovko, 96 ENDF/B-VI JENDL-3.3 JEFF-3.0/A GNASH this evaluation

1

10

0

10

-4

10

-1

-5

10

10

10

12

14

16

18

20

22

24

26

28

30

Neutron energy [MeV]

-2

10

-1

10

0

10

1

10

Neutron energy [MeV]

181

Fig. 8. Evaluated cross-sections for n + Ta exclusive nuclear reactions. Experimental data [57–59] – for (n, xn), [60–63] – for (n, a), [61,62,64–67] – for (n, p), [68] and systematics result [69] – for (n, t), [70–77] – for (n, c) are shown.

for the cross-section of some selected reactions channels are shown in Fig. 8. The (n, 2n) and (n, 3n) reaction channels show the highest cross-sections of the exclusive reactions above 1 MeV and are the most important for neutron transport calculations. We used GNASH results for the evaluation of these reactions without any modification. The experimental

results by Frehaut [58] for the (n, 2n) cross-section were reported to be low by 10% [78]. Thus it can be deduced that the GNASH results fit well the experimental (n, 2n) data. The ENDF/B-VI evaluation shows worse agreement with the experiments for this reaction channel. The 181 Ta(n, p) cross-section is well measured up to 20 MeV and all evaluations describe it adequately. The results of

P. Pereslavtsev, U. Fischer / Nucl. Instr. and Meth. in Phys. Res. B 248 (2006) 225–241

our evaluation are slightly normalized GNASH data. The ENDF/B-VI library contains evaluations only for (n, 2n), (n, 3n), (n, c) and (n, p) exclusive reactions. Additional investigations were required for evaluating the data of the weak (n, a), (n, 3He) and (n, t) reaction channels. The experimental data base which is needed to establish optical model potentials for complex particles (deuterons, tritons, helions and a-particles) is not as rich as for neutrons and protons. Due to the lack of high energy measurements, the OMPs for these particles are not optimal. This could lead to over- or underestimations of the exclusive cross-sections. In addition, the application range in energy is not sufficient enough, the Becchetti OMP for tritons and helions e.g. is applicable only up to 50 MeV. A possible solution was found to be the folding approach that was briefly described above. We performed a comparison of GNASH results with different sets of the transmission coefficients for tritons, helions and a-particles. The folding approach [18], however, does not account for properties of the complex particles. The GNASH results for (n, a) and (n, t) cross-sections, Fig. 8, demonstrate clear the weakness of the folding method used. The only advantage of this approach is its applicability for a wide energy range. In case of the neutron and proton OMPs of Koning and Delaroche, for instance, the upper energy limit is 200 MeV. Fig. 9 shows the total reaction cross-sections for incident deuterons, helions and a-particles. It is evident that the folding approach systematically underestimates reaction cross-section for complex particles. The authors of the TALYS code [18] solved this problem by making use of an empirical estimation of the non-elastic cross-sections for complex charged particles. Although there is an option for the use of the folding approach in TALYS, the above mentioned approach based on experimental data for non-elastic cross-sections for deuterons up to alphas is generally used instead. The use of available global optical potentials gives much more accurate results. The exclusive cross-sections calculated with the folding approach seem to have an energy shift (see for example the (n, t) channel, Fig. 8). This is due to the suppressed inverse reaction cross-section for complex particles calculated in this way. Our evaluation of the exclusive reaction cross-sections below 20 MeV with complex particles in the exit channel therefore was based on the global OMPs mentioned above rather than the folding approach. For tritons and helions above 20 MeV we applied nevertheless the folding method for calculating the emission spectra and re-normalized them to the data at 20 MeV produced with global OMPs. For the neutron capture cross-section we adopted JENDL-3.3 data below 4 MeV. Above we used normalized GNASH results taking into account measurements at 14 MeV, Fig. 8. 4.2. Exclusive nuclear reactions (isomer production) General purpose nuclear data files in general do not contain cross-section data for the isomer production, although

233

the ENDF-6 format rules allow to store such data by making use of the MF = 8, 9, 10 file sections. In this evaluation we did not include results for the isomer production because such data are given in dedicated activation data libraries that cover the same energy range. Isomer production data are provided by GNASH, however and we use them to check the level scheme for a particular nuclide. In Fig. 10 we present our results for the 180gTa (T1/2 = 1.2 · 1015 years) and 180mHf (T1/2 = 5.5 h) production cross-sections. 4.3. Secondary particle emission spectra below 20 MeV Special care needs to be devoted to the evaluation of the secondary particle emission spectra since they are of the highest importance for transport calculations. We applied different representation schemes for storing the particle emission spectra below and above 20 MeV neutron incident energy. According to ENDF-6 format rules for neutron transport files exclusive neutron emission spectra should be presented for all reactions with neutrons in the exit channel. Therefore neutron emission spectra are given on the data file for all such reactions which were considered in the evaluation below 20 MeV. Above this incident energy, particle emission spectra are given for the lumped MT = 5 reaction. The MT = 5 cross-section is set to zero below 20 MeV. Charged particle emission spectra are given for the (n, p), (n, d), (n, t), (n, 3He) and (n, a) exclusive reactions below 20 MeV in separate sections. The format of spectra representation is discussed below. Above 20 MeV, the charged particle emission spectra are included in the lumped MT = 5 reaction section. Exclusive neutron emission spectra are not produced in GNASH. The first attempt to calculate the exclusive spectra using GNASH was made by MacFarlane and Foster [89]. Recently the developers of the EMPIRE-2.19 code presented a similar approach called population method [90]. We elaborated an interface for the GNASH code to calculate exclusive spectra based on this approach. Experimental data for the 181Ta(n, xn) neutron emission spectra are only available up to 20 MeV neutron incident energy. Results of the evaluated neutron emission spectra are compared to the available measurements in Fig. 11. There are included results of the recent REX (Russian ENDF/B-VI eXtension) data library [4] which contains extensions of ENDF/B-VI data evaluations up to 150 MeV where the cross-section data below 20 MeV have not been touched. Fig. 11 shows the lumped neutron emission spectrum which is the sum over all exclusive spectra with neutrons in the exit channel. It is noted that the newly evaluated neutron spectra agree well with the measurements over the entire range of energies. ENDF/B-VI and JENDL-3.3 data can reproduce well the evaporation peaks but underestimate the continuous high energy tails of the spectra. The REX data for 181Ta includes ENDF/B-VI data below 20 MeV and does not contain high energy inelastic scattering peaks.

234

P. Pereslavtsev, U. Fischer / Nucl. Instr. and Meth. in Phys. Res. B 248 (2006) 225–241 1800

3500 40

208

d+ Ca

d+ Pb

1600

3000

2500 1200

Cross section [mb]

Cross section [mb]

1400

1000 800 600

Auce, 96 Bojowald folding

400

2000

1500

Wu, 79 Auce, 96 Mayo, 65 Bojowald folding

1000

500

200 0

0 0

20

40

60

80

100

120

140

0

20

40

Deuteron energy [MeV]

60

80

100

120

140

Deuteron energy [MeV]

1600

3500 3

40

He + Ca

3

208

140

160

He +

1400

Pb

3000

2500

Cross section [mb]

Cross section [mb]

1200 1000 800 600

Ingemarsson, 01 Beccheti folding

400 200

20

40

60

80

100

120

1500

1000

Ingemarsson, 01 Beccheti folding

500

0 0

2000

140

160

0

180

0

Alpha energy [MeV]

20

40

60

80

100

120

180

Alpha energy [MeV]

1800

3500

α+

1600

40

α+

Ca

208

Pb

3000

Cross section [mb]

Cross section [mb]

1400 1200 1000 800 600

Ingemarsson, 00 Auce, 94 Avrigeanu folding

400 200

50

100

2000

1500

Auce, 94 Ingemarsson, 00 Avregeanu folding

1000

500

0 0

2500

150

200

0 0

50

Alpha energy [MeV]

Fig. 9. Total reaction cross-sections for incident deuterons, helions and alphas for

The angular distributions calculated for neutrons and charged particles are based on the Kalbach systematics [96]. In combination with the energy emission spectra this approach provides double-differential particle emission spectra. Fig. 12 displays comparisons of evaluated and measured double-differential spectra for incident 14 MeV neutrons. To enable the restoring of these data following Kalbach systematics, the pre-equilibrium fractions calcu-

100

150

200

Alpha energy [MeV] 40

Ca and

208

Pb. Experimental data [79–84].

lated by GNASH are given in the file along with the particle energy emission spectra. The evaluation of photon production data is fully based on GNASH results. Below 20 MeV the evaluation contains photon production spectra for all exclusive reactions. The angular distributions of the secondary photons are assumed to be isotropic. Results of the evaluations for neutron incident energies of 14 and 18 MeV are shown in Fig. 13.

P. Pereslavtsev, U. Fischer / Nucl. Instr. and Meth. in Phys. Res. B 248 (2006) 225–241

235

1

10

181

181

180m

Ta(n,d+np)

Hf

0

Cross section [mb]

Cross section [mb]

10

-1

10

Begun, 01 Filatenkov, 01 JEFF-3.0/A GNASH this evaluation

-2

10

-3

10

-4

10

8

10

12

14

Neutron energy [MeV]

Fig. 10.

180g

Ta and

20

22

24

26

28

30

Hf production cross-sections. Experimental data [61,62,67,85–88] are shown.

4

4

10

6.7 MeV

181

8 MeV

Ta(n,xn)

181

Ta(n,xn)

3

3

10

ds/dE [mb/MeV]

10

ds/dE [mb/MeV]

18

180m

10

2

10

Marcinkowski, 93 Simakov, 92 ENDF/B-VI JENDL-3.3 this evaluation

1

10

2

10

Simakov, 92 JENDL-3.3 this evaluation

1

10

0

0

10

10

0

1

2

3

4

5

6

0

7

1

2

3

4

5

6

7

8

Neutron emission energy [MeV]

Neutron emission energy [MeV] 4

4

10

10

14 MeV

181

Ta(n,xn)

20 MeV 10

ds/dE [mb/MeV]

2

10

Pavlik, 88 Takahashi, 89 Takahashi, 92 Hermsdorf, 82 ENDF/B-VI JENDL-3.3 this evaluation

1

10

181

Ta(n,xn)

Marcinkowski, 93 REX ENDF/B-VI JENDL-3.3 this evaluation

3

3

10

ds/dE [mb/MeV]

16

Neutron energy [MeV]

2

10

1

10

0

10

0

10

0

2

4

6

8

10

12

14

Neutron emission energy [MeV]

Fig. 11. Evaluated

0

2

4

6

8

10

12

14

16

18

20

Neutron emission energy [MeV]

181

Ta(n, xn) neutron emission spectra below 20 MeV. Experimental data [59,91–95] are given.

4.4. Secondary particle emission spectra above 20 MeV The high energy part of the file contains the total, elastic scattering and lumped MT = 5 cross-sections as well as secondary particle emission spectra and recoil nuclei spectra.

The first two cross-sections are continuous and were evaluated from thermal energies up to 150 MeV. The lumped MT = 5 section actually starts from 20 MeV and equals the total neutron reaction cross-section. For all emitted particles and recoil nuclei the energy dependent yields are

236

P. Pereslavtsev, U. Fischer / Nucl. Instr. and Meth. in Phys. Res. B 248 (2006) 225–241

En=14 MeV

2

10

1

10

0

10

2

4

6

8

10

12

1

0

10

-1

14

0

2

Emitted neutron CM energy [MeV]

4

6

8

10

θ=120

2

dσ/dEdΩ [mb/sr MeV]

dσ/dEdΩ [mb/sr MeV]

0

10

6

8

10

12

14

Emitted neutron CM energy [MeV]

ο

1

10

0

10

-1

10

4

θ=150

2

10

1

2

14

En=14 MeV

ο

10

0

12

Emitted neutron CM energy [MeV]

En=14 MeV 10

ο

10

10 0

θ=75

2

10

dσ/dEdΩ [mb/sr MeV]

dσ/dEdΩ [mb/sr MeV]

θ=30

En=14 MeV

ο

10

-1

0

2

4

6

8

10

12

14

Emitted neutron CM energy [MeV]

Fig. 12. Comparison of the evaluated and measured ([97] filled and [98] open symbols) double-differential neutron emission cross-sections for 14 MeV incident neutrons.

given. In combination with the MT = 5 cross-section the emission spectra can be retrieved. For neutrons and charged particles the emission spectra are stored in the centre-of-mass frame and the pre-equilibrium fractions are given to enable the restoring of double-differential spectra according to the Kalbach systematics [96]. The inclusion of recoil spectra on the evaluated data file is required for radiation damage and nuclear heating calculations. We consider as recoil nuclei all nuclei with a mass number greater four. The model we used for recoil spectra calculations is described in detail in [3,101]. We developed a dedicated processing code for calculating and storing of recoil spectra in ENDF-6 format. The GNASH output file contains angle–integrated center-of-mass channel energy spectra for all decaying compound nuclei (i.e. two-body decay into particle and a recoil). In the first processing step the transformation of this channel spectrum into the center-of-mass spectrum for the recoil nucleus is performed using the population method mentioned above. The center-of-mass to laboratory frame transformation is then made in the second step. The Kalbach systematics is here applied for the integration over the center-of-mass angular

distributions for the recoil nuclei. The preequilibrium fractions for the Kalbach systematics are given in the GNASH output file as a function of the secondary particle emission energy. The average laboratory speed of the decaying compound (boost speed) is determined from the laboratory frame energy spectrum from the previous decay. All additional information such as masses of the nuclides and levels schemes is read from supplementary files available for GNASH calculations. The calculated recoil spectra are tabulated as angle–integrated energy distributions in the laboratory frame assuming the angular distributions to be isotropic. Total photon emission energy spectra are given in the laboratory frame with an isotropic angular distribution. Fig. 13 includes results for neutron incident energies of 35 and 70 MeV. The experimental data given there were actually measured over a wide energy range of neutron incident energies. The specified neutron incident energies of 35 and 70 MeV are mean values. Fig. 14 compares results of the evaluated particle emission spectra with revised REX data [102] for incident 150 MeV neutrons. Problems observed in the high energy

P. Pereslavtsev, U. Fischer / Nucl. Instr. and Meth. in Phys. Res. B 248 (2006) 225–241

237

3

3

10

10

En=18 MeV

En=14 MeV θ=125

2

θ=125

2

10

dσ/dEdΩ [mb/sr MeV]

dσ/dEdΩ [mb/sr MeV]

10

ο

1

10

0

10

-1

1

10

0

10

-1

10

10

-2

-2

10

10

0

2

4

6

8

10

12

14

16

18

0

20

2

4

6

8

10

12

14

16

18

20

22

24

Emitted γ energy [MeV]

Emitted γ energy [MeV] 3

3

10

10

En=70 MeV

En=35 MeV 2

θ=90

ο

2

θ=90

10

dσ/dEdΩ [mb/sr MeV]

10

dσ/dEdΩ [mb/sr MeV]

ο

1

10

0

10

-1

10

-2

10

ο

1

10

0

10

-1

10

-2

10

-3

-3

10

-4

10

10

-4

10

0

5

10

15

20

25

30

35

40

45

Emitted γ energy [MeV]

0

10

20

30

40

50

60

70

Emitted γ energy [MeV]

Fig. 13. Evaluated double-differential emission spectra for photons, compared to experimental data ([99] filled symbols and [100] open symbols). The updated REX data [102] are given with short dashed lines and the results of the present evaluation are shown with solid lines.

charged particle emission spectra calculated by GNASH were already reported [47,48]. The model of Chadwick et al. [50] does not account for multiple pre-equilibrium emission of complex charged particles. Due to this fact the complex particle emission spectra calculated by GNASH show a depression in the middle range of the spectra. In particular this problem exists for the emission of a-particles. In addition, there are large uncertainties in the related total particle production cross-section at high energies. The total deuteron production cross-section, for example, is about 90 and 370 mb in our evaluation and in the REX library, respectively. There are no other data available for n + 181Ta deuteron production at high energies for comparison. For some other heavy nuclides, however, such data are included in the evaluated data files. There is, for example, the total deuteron production cross-section for 209Bi and the stable 204,206,207,208Pb isotopes in JEFF-3.1 [103] which amounts to about 140 and 130 mb, respectively, at 150 MeV neutron incident energy. In the JENDL high energy data library [7] the deuteron production cross-section for the stable tungsten isotopes at 150 MeV is about 50 mb. Therefore we consider our

evaluation for the total deuteron production cross-section of 181T as reasonable. Comparisons of proton and a-particle production crosssections at high energies are shown in Fig. 15. It is pointed out that all results shown were obtained with different computer codes and models. It is noted that the BISERM data [104] were elaborated with a global approach for a variety of nuclides taking into account a variety of high energy experimental data. 5. Evaluated file structure The evaluated data were processed into a complete general purpose data file according to the ENDF-6 format rules. Below 20 MeV the data file is organized in the traditional way except the presence of the lumped MT = 5 section, see Table 2. The evaluated total and elastic scattering cross-sections are given up to 150 MeV. Below 20 MeV the cross-section of the MT = 5 reaction is set to zero. The energy–angle distributions for secondary particles below 20 MeV are stored on MF = 6 file section thus maintaining the energy–angle correlations inherent to

238

P. Pereslavtsev, U. Fischer / Nucl. Instr. and Meth. in Phys. Res. B 248 (2006) 225–241 2

150 MeV

10

181

Ta(n,xn)

150 MeV

181

Ta(n,xp)

3

ds/dE [mb/MeV]

ds/dE [mb/MeV]

10

this evaluation REX

2

10

1

10

0

10

1

10

0

-1

10

10

0

20

40

60

80

100

120

140

0

20

Neutron emission energy [MeV]

40

60

80

100

120

140

Proton emission energy [MeV] 2

2

10

10

181

150 MeV

150 MeV

Ta(n,xd)

181

Ta(n,xt)

1

10 1

ds/dE [mb/MeV]

ds/dE [mb/MeV]

10

0

10

0

10

-1

10

-2

10

-1

10

-3

10

-4

10

-2

10

0

20

40

60

80

100

120

0

140

20

40

60

80

100

120

140

Triton emission energy [MeV]

Deuteron emission energy [MeV] 2

0

10

10

150 MeV

181

150 MeV

3

Ta(n, He)

181

Ta(n,xα)

1

10

ds/dE [mb/MeV]

ds/dE [mb/MeV]

-1

10

-2

10

0

10

-1

10

-3

10

-2

10

-3

10

-4

10

0

20

40

60

80

100

120

140

3

He emission energy [MeV]

0

20

40

60

80

100

120

140

α emission energy [MeV]

Fig. 14. Evaluated particle emission spectra for 150 MeV neutrons compared with modified REX [102] data.

many particle reactions. Charged particle emission spectra were included below 20 MeV to provide the data for accurate radiation damage and nuclear heating calculations. The charged particle emission spectra are represented on the file section MF = 6 for the individual MT = 103–107

reactions (rather than including them in the MT = 5 reaction section). For storing the photon production the MF = 12–15 file sections were used. The elastic scattering angular distributions are presented in tabular format for all incident energies.

P. Pereslavtsev, U. Fischer / Nucl. Instr. and Meth. in Phys. Res. B 248 (2006) 225–241

239

Fig. 15. Comparison of the evaluated total proton and a-production cross-sections with the data from BISERM, modified REX [102] libraries and results from [105].

Table 2 Content of the ENDF data file prepared in this work for n + 181Ta MF file

MT reaction section

MF = 1

451

File description

MF = 2

151

JENDL-3.3

MF = 3

1 2 4 5 16, 17, 22, 24, 28, 41, 51–70, 91, 102, 103, 104, 105, 106, 107

150 150 20 150 20

MF = 4

2 51–70

150 20

MF = 6

5

150

16, 17, 22, 24, 28, 41, 91, 103, 104, 105, 106, 107

20

MF = 12

16, 17, 22, 24, 28, 41, 51–70, 91, 102, 103, 104, 105, 106, 107

20

MF = 14

16, 17, 22, 24, 28, 41, 51–70, 91, 102, 103, 104, 105, 106, 107

20

MF = 15

16, 17, 22, 24, 28, 41, 91, 102, 103, 104, 105, 106, 107

20

The high energy part of the evaluated data file contains the following file sections: MF = 3 with cross-sections for the MT = 1, 2, 5 reactions (total, elastic scattering and lumped particle emission), MF = 4 with angular distributions for MT = 2 and MF = 6 with energy–angle distributions for MT = 5. All other cross-sections are zero above 20 MeV neutron incident energy. The combination of MF = 3 (MT = 5) and MF = 6 (MT = 5) data enables the recovering of the double-differential spectra for the secondary particles and recoil nuclei. 6. Conclusions A complete data evaluation of nuclear cross-sections for general purpose applications was performed for the reaction system n + 181Ta up to 150 MeV neutron incident energy. Use was made of the nuclear model codes

Maximum energy, MeV

Comments

Starts at 20 MeV

CM particle spectra LAB photon and recoil spectra CM spectra

ECIS96 for optical model calculations and GNASH for nuclear reaction cross-section calculations including the multiple pre-equilibrium emission of the particles. The application of these codes enabled the continuous evaluation of neutron induced cross-section data from 0.001 to 150 MeV. High energy experimental data were taken into account for evaluating the total cross-section. Global optical model potentials were used for neutrons, protons, deuterons and a-particles. Optical model potentials for tritons and 3He were constructed on the basis of proton and neutron potentials. To improve the neutron emission spectra, collective excitations were included in the GNASH calculations. Double-differential cross-sections of the emitted particles were calculated on the basis of the Kalbach systematics. A complete general purpose data file in ENDF-6 format was finally prepared covering the entire energy range from thermal energies up to

240

P. Pereslavtsev, U. Fischer / Nucl. Instr. and Meth. in Phys. Res. B 248 (2006) 225–241

150 MeV. The data file was verified with standard ENDF6 format checkers. JENDL-3.3 data were adopted to some extent at lower energies. ENDF/B-VI data were not used due to a rather poor quality of the 181Ta evaluation which was taken over from the earlier ENDF/B-IV version of 1972. The newly evaluated data are in good agreement with measurements available for the 181Ta cross-sections and particle emission spectra. The ENDF data file prepared for n + 181Ta is suitable for a broad range of applications including fission and fusion technology and accelerator driven systems.

[18]

[19] [20] [21] [22] [23]

Acknowledgements This work has been performed in the framework of the nuclear fusion programme of Forschungszentrum Karlsruhe and is supported by the European Union within the European Fusion Technology Programme. References [1] Yu.A. Korovin, A.Yu. Konobeyev, P.E. Pereslavtsev, A.Yu. Stakovsky, C. Broeders, I. Broeders, U. Fischer, U. von Mo¨llendorff, Nucl. Instr. and Meth. A 463 (2001) 544. [2] A. Koning, J. Delaroche, O. Bersilon, Nucl. Instr. and Meth. A 414 (1998) 49. [3] M.B. Chadwick, P.G. Young, S. Chiba, S.C. Frankle, G.M. Hale, H.G. Hughes, A.J. Koning, R.C. Little, R.R. MacFarlane, R.E. Prael, L.S. Waters, Nucl. Sci. Eng. 131 (1999) 293. [4] Yu.A. Korovin, A.Yu. Konobeyev, G.B. Pilnov, A.Yu. Stankovski, in: Proc. Int. Conf. on Nuclear Data for Science and Technology, Santa Fe, New Mexico, 26 September–1 October 2004, p. 113. [5] A.J. Koning, O. Bersillon, R.A. Forest, R. Jacqmin, M.A. Kellet, A. Nouri, P. Rullhusen, in: Proc. Int. Conf. on Nuclear Data for Science and Technology, Santa Fe, New Mexico, 26 September–1 October 2004, p. 177. [6] P. Pereslavtsev, U. Fischer, in: Proc. Int. Conf. on Nuclear Data for Science and Technology, Santa Fe, New Mexico, 26 September–1 October 2004, p. 215. [7] Y. Watanabe, T. Fukahori, K. Kosako, N. Shigyo, T. Murata, N. Yamano, T. Hino, K. Maki, H. Nakashima, N. Odano, S. Chiba, in: Proc. Int. Conf. on Nuclear Data for Science and Technology, Santa Fe, New Mexico, 26 September–1 October 2004, p. 326. [8] J.-Ch. Sublet, A.J. Koning, R.A. Forest, J. Kopecky, in: Proc. Int. Conf. on Nuclear Data for Science and Technology, Santa Fe, New Mexico, 26 September–1 October 2004, p. 203. [9] J. Raynal, Notes on ECIS94, Report CEA-N-2772, Centre d’Etude de Saclay CEA, Saclay, France, 1994. [10] P.G. Young, E.D. Arthur, M.B. Chadwick, in: Workshop on Nuclear Reaction Data and Nuclear Reactors, Trieste, Italy, 15 April–17 May 1996, p. 227. [11] A.J. Koning, J. Delaroche, Nucl. Phys. A 713 (2003) 231. [12] P.G. Young, E.D. Arthur, M. Bozian, T.R. England, G.M. Hale, R.J. LaBauve, R.C. Little, Report LA-11753-MS, Los Alamos National Laboratory LANL, USA, 1990, p. 9. [13] J. Bojowald, H. Machner, H. Nann, W. Oelert, M. Rogge, P. Turek, Phys. Rev. C 38 (1988) 1153. [14] V. Avrigeanu, P.E. Hodgson, Phys. Rev. C 49 (1994) 2136. [15] F.D. Beccheti, G.W. Greenlees, in: H.H. Barschall, W. Haeberly (Eds.), Polarization Phenomena in Nuclear Reactions, The University of Wisconsin Press, 1971, p. 682. [16] S. Watanabe, Nucl. Phys. 8 (1958) 484. [17] D.G. Madland, in: Proc. of a Specialists Meeting on Preequilibrium Nuclear Reactions, Semmering, Austria, 10–12 February 1998,

[24] [25] [26] [27] [28]

[29] [30] [31]

[32]

[33] [34]

[35] [36] [37]

[38] [39] [40] [41] [42] [43] [44] [45] [46] [47] [48] [49] [50] [51] [52]

Report NEANDC-245 ‘U’, Nuclear Energy Agency, Paris, 1998, p. 103. A.J. Koning, S. Hilaire, M. Duijvestijn, Report 21297/04.62741/P FAI/AK/AK, Nuclear Research and Consultancy Group NRG, Petten, The Netherlands, 2004. R.W. Finlay, W.P. Abfalterer, G. Fink, E. Montei, T. Adami, P.W. Lisowski, G.L. Morgan, R.C. Haight, Phys. Rev. C 47 (1993) 237. W.P. Poenitz, J.F. Whalen, A.B. Smith, Nucl. Sci. Eng. 78 (1981) 333. W.P. Poenitz, J.F. Whalen, Report ANL-NDM-80, Argonne National Laboratory, USA, 1983. I. Tsubone, Y. Nakajima, Y. Furuta, Y. Kanda, Nucl. Sci. Eng. 88 (1984) 579. T.Y. Byoun, Progress Report Chicago Operations Office COO-305834, 7, USA, 1973. D.G. Foster Jr., D.W. Glasgow, Phys. Rev. C 3 (1971) 576. C.I. Hudson Jr., W.S. Walker, S. Berko, Phys. Rev. 128 (1962) 1271. S.A. Cox, E.E. Dowling Cox, Report ANL-7935, Argonne National Laboratory, USA, 1972. W.B. Gilboy, J.H. Towle, Nucl. Phys. 42 (1963) 86. B. Holmqvist, T. Wiedling, S.G. Johansson, G. Lodin, A. Kiss, B. Gustavsson, B. Antolkobic, Report AE-366, Aktiebolaget Atomenergi, Stockholm/Studsvik, Sweden, 1969. M. Walt, J.R. Beyster, Phys. Rev. 98 (1955) 677. M. Walt, H.H. Barschall, Phys. Rev. 93 (1954) 1062. V.G. Nikolenko, Zo-In-Ok, A.B. Popov, G.S. Samosvat, Report JINR-P3-85-133, Joint Institute for Nuclear Researches, Dubna, Russia, 1985 (in Russian). L.Ya. Kazakova, V.E. Kolesov, V.I. Popov, O.A. Sal’nikov, V.M. Sluchevskaya, V.I. Trykova, in: Proc. Int. Conf. on the Study of Nuclear Structure with Neutrons, Antwerpen, Belgium, 19–23 July 1965, p. 576. N.P. Glazkov, J. Nucl. Energy AB 18 (1964) 656 (in Russian). D.L. Broder, A.F. Gamalij, A.I. Lashuk, B.V. Nesterov, I.P. Sadokhin, Report Fiz.-Energ. Institute FEI-155, Russia, 1969 (in Russian). W.L. Rogers, D.I. Garber, E.F. Shrader, Bull. Am. Phys. Soc. 6 (1961) 61. V.C. Rogers, L.E. Beghian, F.M. Clikeman, Nucl. Sci. Eng. 45 (1971) 297. S.P. Simakov, G.N. Lovchikova, O.A. Sal’nikov, G.V. Kotel’nikova, A.M. Trufanov, Vop. At. Nauki i Tekhn. Ser. Yadernye Konstanty 5 (49) (1982) 17 (in Russian). R.O. Owens, J.H. Towle, Nucl. Phys. A 112 (1968) 337. J.R. Beyster, M. Walt, E.W. Salmi, Phys. Rev. 104 (1956) 1319. S.E. Darden, R.B. Perkins, R.B. Walton, Phys. Rev. 100 (1955) 1315. A.B. Smith, Report ANL-NDM-160, Argonne National Laboratory, USA, 2005. L.F. Hansen, F.S. Dietrich, B.A. Pohl, C.H. Poppe, C. Wong, Phys. Rev. C 31 (1985) 111. R.E. Benenson, K. Rimawi, E.H. Sexton, B. Center, Nucl. Phys. A 212 (1973) 147. W.G. Cross, R.G. Jarvis, Nucl. Phys. 15 (1960) 155. G. Gerstein, J. Niederer, K. Strauch, Phys. Rev. 108 (1957) 427. D.J. Steinberg, J.N. Palmieri, A.M. Cormack, Nucl. Phys. 56 (1964) 46. A.V. Ignatyuk, V.P. Lunev, Yu.N. Shubin, E.V. Gai, N.N. Titarenko, Nucl. Sci. Eng. 136 (2000) 340. E. Raeymackers, S. Benck, N. Nica, I. Slypen, J.P. Meulders, V. Corcaciuc, A.J. Koning, Nucl. Phys. A 726 (2003) 210. C. Kalbach, Report LA-10248-MS, Los Alamos National Laboratory, USA, 1985. M.B. Chadwick, P.G. Young, D.C. George, Y. Watanabe, Phys. Rev. C 50 (1994) 996. A.V. Ignatyuk, G.N. Smirenkin, A.S. Tishin, Sov. J. Nucl. Phys. 21 (1975) 255 (in Russian). J. Kopecky, M. Uhl, Phys. Rev. C 41 (1990) 1941.

P. Pereslavtsev, U. Fischer / Nucl. Instr. and Meth. in Phys. Res. B 248 (2006) 225–241 [53] C. Kalbach, Phys. Rev. C 62 (2000) 044608. [54] A.J. Koning, M.C. Duijvestijn, Nucl. Phys. A 744 (2004) 15. [55] T. Begya, O. Bersillon, R. Capote, T. Fukahori, G. Zhigang, S. Goriely, M. Herman, A.V. Ignatyuk, S. Kailas, A. Koning, P. Oblozhinsky, V. Plujko, P. Young, Handbook for Calculations of Nuclear Reaction Data: Reference Input Parameter Library RIPL-2, WWW-address: http://www-nds.iaea.org/RIPL-2/, IAEA, Vienna, 2005. [56] B. Firestone, in: Table of Isotopes, eighth ed., Lawrence Berkley National Laboratory, University of California, A Wiley-Interscience Publication, New York, USA, 1996. [57] L.R. Veeser, E.D. Arthur, P.G. Young, Phys. Rev. C 16 (1977) 1792. [58] J. Frehaut, A. Bertin, R. Bois, J. Jary, in: Int. Symp. on Neutron Cross Sections from 10 to 50 MeV, Upton, LI, USA, 12–14 May 1980. [59] A. Takahashi, Y. Sasaki, H. Sugimoto, Report IAEA INDC(JAP)118/L, International Atomic Energy Agency, 1989. [60] S.K. Mukherjee, H. Bakhru, in: Proc. IAEA Symp. on Inelastic Scattering of Neutrons in Solids and Liquids, Bombay, India, 15–19 December 1964, p. 244. [61] A.A. Filatenkov, S.V. Chuvaev, Report RI-258, Khlopin Radievij Inst., St. Petersburg, Russia, 2001 (in Russian). [62] S.V. Begun, I.M. Kadenko,V.K. Maidanyuk, V.M. Nepluyuev, V.A. Plujko, G.I. Primenko, V.K. Tarakanov, in: Proc. 51 Int. Conf. on Nuclear Spectroscopy and Nuclear Structure, Sarov, Russia, 3–8 September 2001, p. 203. [63] A.D. Majeddin, V. Semkova, R. Doczi, C.M. Buczko, J. Csikai, EXFOR 31481, 1997. [64] R. Woelfle, A. Mannan, S.M. Qaim, H. Liskien, R. Widera, Appl. Radiat. Isot. 39 (5) (1988). [65] X. Kong, Y. Wang, J. Yang, J. Yuan, X. Wang, Chin. J. Nucl. Phys. 14 (3) (1992) 239. [66] Y. Kasugai, H. Yamamoto, A. Takahashi, T. Iida, K. Kawade, Report IAEA INDC(JPN)-163/L, 277, International Atomic Energy Agency, 1992. [67] H.-L. Lu, W. Zhao, P. Fan, Report IAEA INDC(CPR)-16, International Atomic Energy Agency, 1989. [68] R. Woelfle, S.M. Qaim, H. Liskien, R. Widera, Radiochim. Acta 50 (1990) 5. [69] Yu.A. Korovin, A.Yu. Konobeyev, P.E. Pereslavtsev, Nucl. Instr. and Meth. B 93 (1994) 409. [70] Chr. Necheva, D. Kolev, M. Vlasarev, J. Phys. GL 20 (1994) 33. [71] H. Xu, Z. Xiang, Y. Mu, Y. Li, J. Liu, in: Proc. Int. Conf. on Nuclear Data for Science and Technology, Mito, Japan, 30 May–3 June 1988, p. 803. [72] M. Wagner, H. Warhanek, Acta Phys. Austriaca 52 (1980) 23. [73] J.R.D. Lepine, R.A. Douglas, H.A. Maia, Nucl. Phys. A 196 (1972) 83. [74] M. Budnar, F. Cvelbar, E. Hodgson, A. Hudoklin, V. Ivkovic, A. Likar, M.V. Mihailovic, R. Martincic, M. Najzer, A. Perdan, M. Potokar, V. Ramsak, Report IAEA INDC(YUG)-6, International Atomic Energy Agency, 1979. [75] J.A. Miskel, K.V. Marsh, M. Lindner, R.J. Nagle, Phys. Rev. 128 (1962) 2717. [76] V.N. Kononov, B.D. Jurlov, E.D. Poletaev, V.M. Timokhov, G.N. Manturov, Vopr. At. Nauki i Tekhn. Ser. Jad. Kon. 22 (1977) 29 (in Russian). [77] M.V. Bokhovko, V.N. Kononov, N.S. Rabotnov, A.A. Voevodskiy, G.N. Manturov, V.M. Timokhov, EXFOR 41225, 1996. [78] H. Vonach, A. Pavlik, B. Strohmaier, Nucl. Sci. Eng. 106 (1990) 409. [79] A. Auce, R.F. Carlson, A.J. Cox, A. Ingemarsson, R. Johansson, P.U. Renberg, O. Sundberg, G. Tibell, Phys. Rev. C 53 (1996) 2919. [80] J.R. Wu, C.C. Chang, H.D. Holmgren, Phys. Rev. C 19 (1979) 370. [81] S. Mayo, W. Schimmerling, M.J. Sametband, Nucl. Phys. 62 (1965) 393.

241

[82] A. Auce, R.F. Carlson, A.J. Cox, A. Ingemarsson, R. Johansson, P.U. Renberg, O. Sundberg, G. Tibell, R. Zorro, Phys. Rev. C 50 (1994) 871. [83] A. Ingemarsson, J. Nyberg, P.U. Renberg, O. Sundberg, R.F. Carlson, A.J. Cox, A. Auce, R. Johansson, G. Tibell, D.T. Khoa, R.E. Warner, Nucl. Phys. A 676 (2000) 3. [84] A. Ingemarsson, G.J. Arendse, A. Auce, R.F. Carlson, A.A. Cowley, A.J. Cox, S.V. Fortsch, R. Johansson, B.R. Karlson, M. Lantz, J. Peavy, J.A. Stander, G.F. Steyn, G. Tibell, Nucl. Phys. A 696 (2001) 3. [85] Y. Ikeda, C. Konno, K. Oishi, T. Nakamura, H. Miyade, K. Kawade, H. Yamamoto, T. Katoh, Report JAERI-1312, Japan Atomic Energy Research Institute, 1988. [86] M. Bormann, A. Behrend, I. Riehle, O. Vogel, Nucl. Phys. A 115 (1968) 309. [87] A.A. Filatenkov, S.V. Chuvaev, V.N. Aksenov, V.A. Yakovlev, A.V. Malyshenkov, S.K. Vasil’ev, M. Avrigeanu, V. Avrigeanu, D.L. Smith, Y. Ikeda, A. Wallner, W. Kutschera, A. Priller, P. Steier, H. Vonach, G. Mertens, W. Rochow, Report RI-252, Khlopin Radievij Institute, St. Petersburg, Russia,1999 (in Russian). [88] R.J. Prestwood, B.P. Bayhurst, Phys. Rev. 121 (1961) 1438. [89] R.E. MacFarlane, D.G. Foster, J. Nucl. Mater. 122–123 (1984) 1047. [90] M. Herman, P. Oblozinsky, R. Capote, M. Sin, A. Trkov, A. Ventura, V. Zerkin, in: Proc. Int. Conf. on Nuclear Data for Science and Technology, Santa Fe, New Mexico, 26 September–1 October 2004, p. 1184. [91] A. Marcinkowski, J. Rapaport, R.W. Finlay, C. Brient, M.B. Chadwick, Nucl. Phys. A 561 (1993) 387. [92] S.P. Simakov, G.N. Lovchikova, V.P. Lunev, V.G. Pronyaev, N.N. Titarenko, A.M. Trufanov, Vop. At. Nauki i Tekhn. Ser. Yadernye Konstanty 4 (1992) 74 (in Russian). [93] A. Pavlik, H. Vonach, Report Institut fu¨r Reaktor und Kernphysik, Vienna, 1988; H. Kalka, M. Torjman, D. Seeliger, Phys. Rev. C 40 (1989) 1619. [94] A. Takahashi, M. Gotoh, Y. Sasaki, H. Sugimoto, Report OKTAVA-92-01, Osaka University, Japan, 1992. [95] D. Hermsdorf, A. Meister, S. Sassonoff, D. Seeliger, K. Seidel, EXFOR 30397, 1982. [96] C. Kalbach, Phys. Rev. C 37 (1988) 2350. [97] S. Matsuyama, T. Okubo, M. Baba, T. Ito, T. Akiyama, N. Ito, N. Hirakawa, Report JAERI JAERI-M-93-046, 345, Japan Atomic Energy Research Institute, 1992. [98] H. Al Obiesi, T. Elfruth, T. Hehl, M. Toepfer, D. Seeliger, K. Seidel, S. Unholzer, Report INDC(GDR)-058/L, International Atomic Energy Agency, 1990. [99] P. Ramakrishnan, G.E. Mitchell, C.R. Gould, S.A. Wender, G.F. Auchampaugh, Nucl. Sci. Eng. 98 (1998) 348. [100] G.L. Morgan, T.A. Love, J.K. Dickens, F.G. Perey, Nucl. Sci. Eng. 62 (1977) 515. [101] M.B. Chadwick, P.G. Young, R.E. MacFarlane, A.J. Koning, in: Proc. 2nd Int. Conf. on Accelerator Driven Transmutation Technology and Applications, Kalmar, Sweden, 3–7 June 1996, p. 483. [102] A.Yu. Konobeyev, private communication, January 2006. [103] A.J. Koning, M.C. Duijvestijn, S.C. van der Mark, R. Klein Meulekamp, A. Hogenbirk, in: Proc. Int. Conf. on Nuclear Data for Science and Technology, Santa Fe, New Mexico, 26 September–1 October 2004, p. 422. [104] A.Yu. Konobeyev, Yu.A. Korovin, V.N. Sosnin, J. Nucl. Mater. 186 (1992) 117; A.Yu. Konobeyev, Yu.A. Korovin, J. Nucl. Mater. 195 (1992) 286. [105] C.H.M. Broeders, A.Yu. Konobeyev, Nucl. Instr. and Meth. B 234 (2005) 387.