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).