32-Ge- 72 BNL,JAERI EVAL-AUG04 Iwamoto,Herman,Mughabghab+ DIST-MAY10 20090805 ----JENDL-4.0 MATERIAL 3231 -----INCIDENT NEUTRON DATA ------ENDF-6 FORMAT History 09-08 The original data were taken from ENDF/B-VII.0. (n,p) and (n,a) were recalculated from partial cross sections. The total cross section was recalculated from partial cross sections. Compiled by K. Shibata (jaea). ***************************************************************** ENDF/B-VII Evaluation, August 2004, O. Iwamoto(BNL,JAERI), M. Herman(BNL), S.F. Mughabghab (BNL), P.Oblozinsky(BNL), A.Trkov(IAEA), V.G.Pronyaev (IPPE) ****************************************************************** This evaluation is combined result of 2 evaluations. a) 2004 evaluation in the thermal, resolved resonance and unresolved resonance regions by Mughabghab. The URR upper energy range is 701.096 keV, given as neutron scattering threshold to the 1-st excited level of Ge-72 (691.43 keV). b) 2004 evaluation in the fast energy region by Iwamoto, Herman, Oblozinsky and Trkov Merging of these 2 evaluations was performed as follows: - Capture cross sections were adopted from evaluation a) up to the URR upper energy, from evaluation b) at higher energies. - Total cross sections were adopted from evaluation a) up to the URR upper energy, from evaluation b) at higher energies. ***************************************************************** RESONANCE ENERGY REGION, S.F. Mughabghab (BNL) and O.Iwamoto(BNL,JAERI), V.G.Pronyaev (IPPE) MF= 2 RESONANCE PARAMETERS RESOLVED RESONANCES REGION (1e-5 eV - 12 keV) Resonance parameters were from ref. [Ma68] applying multilevel Breit-Wigner formalism. Bound level were introduce to describe the recommended thermal capture and scattering cross sections [Mu05]. Resonance energies and widths were modified to reproduce measured total cross section of natural Ge [Ha80]. Calculated 2200 m/s cross sections and resonance integral Cross Section (b) Res. Integral (b) Capture 0.89 0.90 Elastic 8.86 UNRESOLVED RESONANCE REGION (12 keV - 1054 keV) Average resonance parameters were obtained from the resolved energy region as well as systematics [Mu05]. EVPAR code by G. Manturov was used for cross section evaluation in the URR basing on average parameters. Average parameters: S (10**4)(eV)* (meV) s-wave 2.2 150 p-wave 1.0 180 d-wave 3.0 150 * Level spacing at the neutron separation energy of target+n Scattering radius for the URR was adjusted to fit the elastic and total given in MF=3 at 701.096 keV. f-wave contribution was added as background cross section --------------------------------------------------------------- REFERENCES [Ma68] Maletskii et al., Soviet Atomic Energy, 24, 207 (1968) [Mu05] S.F. Mughabghab, "Atlas of Neutron Resonances", to be published 2005 [Ha80] J.A. Harvey, M. Hockaday, EXFOR 13770.004 ***************************************************************** FAST ENERGY REGION, O. Iwamoto(BNL,JAERI), M. Herman(BNL), P. Oblozinsky(BNL) and A.Trkov(IAEA) This is entirely new evaluation for Ge-72 in the region up to 20 MeV. EVALUATION PROCEDURES Adopted procedures are based on careful theoretical analysis utilizing available experimental data, including optical model parameter search and nuclear reaction model calculations. OM parameter search was performed to reporduce measured total cross section for natural Ge with the code CCOM by O. Iwamoto. Nuclear reaction model calculations were performed with the code EMPIRE-II by M. Herman [He01, He02]. This is modularized statistical model code that integrates into a single system a number of important modules and features: - Spherical OM (code SCAT2 by O. Bersillone), and deformed OM including coupled-channels model (code ECIS03 by J. Raynal). - Hauser-Feshbach statistical model including HRTW width fluctuation correction. - Qauntum-mechanical MSD TUL model (codes ORION & TRISTAN by H.Lenske), and MSC NVWY model. - Exciton model (code DEGAS by E. Betak). This code represents good approximation to DSD capture model. - Iwamoto-Harada cluster emission model (code PCROSS). - Complete gamma-ray cascade after emission of each particle, including realistic treatment of discrete transitions. - Access to OM segment of the RIPL-2 library [Ri03]. - Built-in input parameter files, such as masses, level density, discrete levels, OM parameters and gamma strength functions. - ENDF-6 formatting (utility code EMPEND by A. Trkov), coupled to grahpical presentation (utility code ZVView by V.Zerkin). PARAMETERIZATION Optical model - SCAT2 code used for spherical OM parameterization. - For neutrons OM by Wilmore-Hodgson was modified to reproduce total cross section for natural Ge. ---------- U=47.76-0.228*E-0.00118*E**2 W=9.17-0.053*E V_so=7.0 r_u=1.297-0.00076*A+4e-6*A**2-8e-9*A**3 r_w=1.269-0.00037*A+2e-6*A**2-4e-9*A**3 r_so=r_u a_u=0.66 a_w=0.48 a_so=a_u ---------- - For protons, OM by Koning-Delaroche (RIPL-2:OMP-2405) - For alpha particles, OM by V.Avrigeanu et al.(RIPL-2:OMP-9600) Level densities and discrete levels - Gilbert-Cameron level densities were used with energy dependent a-parameter proposed by Ignatyk. The asymptoticvalue of the a-parameter is calculated by the systematics of Iljinov et al. - Discrete levels were taken from RIPL-2 level file that is based on the 1998 version of the ENSDF database. Other parameters and tuning - ECIS03 with DWBA option was used to account for direct contribution to low lying 2+ and 3- discrete levels in (n,n'). Deformation parameters were taken from work of (p,p') analysis [Ke92]. - Preequilibrium components were calculated using the following options: Multistep direct and multistep compound models with default parameters for neutron channel, exciton model with angular momentum coupling (DEGAS) for proton and gamma channels, cluster emissin model by Iwamoto and Harada (PCROSS) for alpha channel - Gamma-ray strength function of modified Lorentzian version 1 (MLO1) by Plujko in RIPL-2 was used. - Asymptotic level density parameter for Ga-72 was multiplied by 1.2 to reproduce experimental data. RESULTS MF=3 Neutron cross sections - EMPIRE calculations were adopted (statistical model, including multistep/preequilibrium decay and direct processes). MT=1 Total - Spherical optical model was adopted. MT=2 Elastic scattering - Calculated as (total - sum of partial cross sections). MT=4, 51-91 Inelastic scattering - EMPIRE calculations were adopted (statistical model with multistep direct & multistep compound component, and DWBA component for low-lying levels). MT=102 Capture - EMPIRE calculations were adopted (statistical model with exciton preequilibrium component as approximation to direct-semidirect capture with fast neutrons). MT=16 (n,2n) taken from EMPIRE calculations MT=17 (n,3n) taken from EMPIRE calculations MT=22 (n,n'a) taken from EMPIRE calculations MT=24 (n,2n'a) taken from EMPIRE calculations MT=28 (n,n'p) taken from EMPIRE calculations MT=45 (n,n'pa) taken from EMPIRE calculations MT=103, 600-649 (n,p) taken from EMPIRE calculations MT=107, 800-849 (n,a) taken from EMPIRE calculations MT=112 (n,pa) taken from EMPIRE calculations MF=4 Angular distributions of secondary neutrons - EMPIRE calculations (including SCAT2 results for elastic scattering) were adopted. MF=6 Energy-angle distributions of reaction products - EMPIRE calculations were adopted. MF=12 Transition probablility arrays for photon production - RIPL-2 level data MF=14 Photon angular distributions - Isotropic distributions were assumed. --------------------------------------------------------------- REFERENCES [He01] M. Herman "EMPIRE-II Statistical Model Code for Nuclear Reaction Calculations", in Nuclear Reaction Data and Nuclear Reactors, eds. N.Paver, M. Herman and A.Gandini, ICTP Lecture Notes 5 (ICTP Trieste, 2001) pp.137-230. [He02] M.Herman, R.Capote, P.Oblozinsky, A.Trkov and V.Zerkin, "Recent Development and Validation of the Nuclear Reaction Code EMPIRE", in Proc. Inter. Conf. on Nuclear Data for Science and Technology, October 7-12, 2001, Tsukuba, Japan, to be published in J.Nucl.Sci.Tech. (2002). [Ke92] M.A.Kennedy, P.D.Cottle, K.W.Kemper, Phys. Rev. C46 1811 (1992). [Ri03] "RIPL-2: Reference Input Parameter Library", to be published, see also "http://www-nds.iaea.org/RIPL-2/". *****************************************************************