12-Mg- 24 DEC,NEDAC EVAL-MAR87 M.HATCHYA(DEC), T.ASAMI(NEDAC) DIST-MAY10 20090828 ----JENDL-4.0 MATERIAL 1225 -----INCIDENT NEUTRON DATA ------ENDF-6 FORMAT HISTORY 87-03 New evaluation was made for JENDL-3. 87-03 Compiled by T.Asami. 93-04 JENDL-3.2 Compiled by T.Nakagawa (ndc/jaeri) ***** modified parts for JENDL-3.2 ******************** (4,91) Changed to the laboratory system *********************************************************** 01-04 Gamma-ray production data were added. Compiled by K.Shibata. ***** modification for JENDL-3.3 ****************************** (1,451) Updated. (3,1) Revised. (3,2) Re-calculated. (3,251) Deleted. (4,2) Transformation matrix deleted. (5,16-91) INT=22. (12,16-107) Added. (14,16-107) Added. (15,16-107) Added. ***************************************************************** 09-08 MF/MT=12/58 was corrected. Compiled by K.Shibata (jaea) mf=1 General information mt=451 Descriptive data and dictionary mf=2 Resonance parameters mt=151 Resolved resonance parameters Resolved parameters for MLBW formula were given in the energy region from 1.0e-5 eV to 520 keV. Parameters were taken from the recommended data of BNL/1/ and the data for a negative resonance were added so as to reproduce the recommended thermal cross sections for capture and scattering/1/. The data for some levels were modified so that the calculated total cross sections of the element Mg were fitted to the experimental data of Hibdon/2/ and Singh/3/. The scattering radius was assumed to be 5.4 fermi. Calculated 2200 m/sec cross sections and resonance integrals are as follows: 2200 m/s cross section(b) res. integral(b) elastic 3.75 capture 0.050 0.0312 total 3.80 mf=3 Neutron cross sections Below 520 keV, no background cross section is given and all the cross-section data are reproduced from the evaluated resolved resonance parameters with the MLBW formula. Above 520 keV, the total and partial cross sections are given in the pointwise form. ***** For JENDL-3.3 ******************************************** Negative background cross sections were considered for mt=1,2 to reproduce the elemental total cross sections of JENDL-3.2 **************************************************************** mt=1 Total Optical and statistical model calculation was made with casthy code/4/. The optical potential parameters used are: V = 49.68, Vso = 7.12 (MeV) Ws = 7.76 - 0.5*En, Wv = 0 (MeV) r = 1.17, rs = 1.09, rso = 1.17 (fm) a = 0.6, aso = 0.6, b = 0.69 (fm) ***** For JENDL-3.3 ******************************************** The elemental data of JENDL-3.2 were taken after subtracting Mg-25,26 contributions. **************************************************************** mt=2 Elastic scattering Obtained by subtracting the sum of the partial cross sections from the total cross section. mt=4, 51-61, 91 Inelastic scattering Calculated with casthy /4/, taking account of the contribution from the competing processes. The direct components for mt=51 and 52 were, calculated with the dwuck/5/. The calculated data for the first level were normalized at 12 MeV to the experimen- tal data/6/. The level data used in these two calculations were taken from ref./7/ as follows: mt level energy(MeV) spin-parity 0.0 0+ 51 1.3686 2+ 52 4.1200 4+ 53 4.2384 2+ 54 5.2361 3+ 55 6.0103 4+ 56 6.4322 0+ 57 7.3479 2+ 58 7.5530 1- 59 7.6162 3- 60 7.7472 1+ 61 7.8120 3+ Levels above 10.0 MeV were assumed to be overlapping. mt=16, 22, 28, 103, 107 (n,2n), (n,na), (n,np), (n,p), (n,a) Calculated with the gnash code/8/ using the above optical model parameters. The (n,2n) cross sections were modified so as to fit to the experimental data. mt=102 Capture Calculated with the casthy code/4/ and normalized to 1.8 mb at 30 keV. mf=4 Angular distributions of secondary neutrons mt=2 Calculated with the casthy code/4/. mt=51-61 Calculated with the casthy code/4/, and contributions from the direct process calculated with the dwuck code/5/ were added to mt=51 and 52. mt=91 Calculated with the casthy code/4/ and transformed into the laboratory system. mt=16, 22, 28 Assumed to be isotoropic in the laboratory system. mf=5 Energy distributions of secondary neutrons mt=16, 22, 28, 91 Calculated with the gnash code/8/. mf=12 Photon multiplicities and transition probabilities mt=16,22,28,91,103,107 Calculated with gnash. mt=51-61 Stored under option-2 (transition probability array). mt=102 Calculated with casthy. mf=14 Photon angular distributions mt=16,22,28,51-61,91,102,103,107 Isotropic. mf=15 Continuous photon energy spectra mt=16,22,28,91,103,107 Calculated with gnash. mt=102 Calculated with casthy. Between 44 and 430 keV, the data measured at Tokyo Institute of Technology /9/ were inserted. References 1) Mughabghab S.F. and Garber D.I. :"Neutron cross sections", Vol. 1, Part B (1984). 2) Hibdon C.T. : taken from exfor (1969). 3) Singh U.N. et al. : Phys. Rev. C10, 2150 (1974). 4) Igarasi S. : J. Nucl. Sci. Tech. 12, 67 (1975). 5) Kunz P.D. : unpublished. 6) Foertsch et al. : Nucl. Instr. Meth. 169, 533 (1980). 7) ENSDF(Evaluated Nuclear Structure Data File) 8) Young P.G. and Arthur E.D. : LA-6947 (1977). 9) Igashira M.: private communication (2000).