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41-Nb- 93 LANL,ANL EVAL-DEC97 M.CHADWICK,P.YOUNG,D.L.SMITH
Ch97,Ch99 DIST-JAN09 20090105
----JEFF-311 MATERIAL 4125 REVISION 2
-----INCIDENT NEUTRON DATA
------ENDF-6 FORMAT
*************************** JEFF-3.1.1 *************************
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** Original data taken from: JEFF-3.1 **
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***************************** JEFF-3.1 *************************
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** Original data taken from: ENDF/B-VI.8 **
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ENDF/B-VI MOD 3 Evaluation, December 1997, M.B. Chadwick and
P.G. Young (LANL)
Los Alamos LA150 Library, produced with FKK/GNASH/GSCAN code
in cooperation with ECN Petten.
This evaluation provides a complete representation of the
nuclear data needed for transport, damage, heating, radioactivity,
and shielding applications over the incident proton energy range
from 1 to 150 MeV. The evaluation utilizes MF=6, MT=5 to
represent all reaction data. Production cross sections and
emission spectra are given for neutrons, protons, deuterons,
tritons, alpha particles, gamma rays, and all residual nuclides
produced (A>5) in the reaction chains. To summarize, the ENDF
sections with non-zero data above are:
MF=3 MT= 2 Integral of nuclear plus interference components
of the elastic scattering cross section
MT= 5 Sum of binary (p,n') and (p,x) reactions
MF=6 MT= 2 Elastic (p,p) angular distributions given as
ratios of the differential nuclear-plus-
interference to the integrated value.
MT= 5 Production cross sections and energy-angle
distributions for emission neutrons, protons,
deuterons, and alphas; and angle-integrated
spectra for gamma rays and residual nuclei that
are stable against particle emission
The evaluation is based on nuclear model calculations that have
been benchmarked to experimental data, especially for n +93Nb and
n +93Nb reactions [Ch98]. We use the GNASH code system [Yo92],
which utilizes Hauser-Feshbach statistical, preequilibrium and
direct-reaction theories. Spherical optical model calculations are
used to obtain particle transmission coefficients for the Hauser-
Feshbach calculations, as well as for the elastic proton angular
distributions.
Cross sections and spectra for producing individual residual
nuclei are included for reactions. The energy-angle-correlations
for all outgoing particles are based on Kalbach systematics
[Ka88].
A model was developed to calculate the energy distributions of
all recoil nuclei in the GNASH calculations [Ch96a]. The recoil
energy distributions are represented in the laboratory system in
MT=5, MF=6, and are given as isotropic in the lab system. All
other data in MT=5,MF=6 are given in the center-of-mass system.
This method of representation utilizes the LCT=3 option approved
at the November, 1996, CSEWG meeting.
Preequilibrium corrections were performed in the course of the
GNASH calculations using the exciton model of Kalbach [Ka77,
Ka85], validated by comparison with calculations using Feshbach,
Kerman, Koonin (FKK) theory [Ch93]. Discrete level data from
nuclear data sheets were matched to continuum level densities
using the formulation of Ignatyuk et al. [Ig75] and pairing and
shell parameters from the Cook [Co67] analysis. Neutron and
charged- particle transmission coefficients were obtained from the
optical potentials, as discussed below. Gamma-ray transmission
coefficients were calculated using the Kopecky-Uhl model [Ko90].
SPECIFIC INFORMATION CONCERNING THE 93Nb EVALUATION
The total neutron cross section was obtained from the Finlay[Fi93]
measurements.
The following optical potentials were used in the GNASH
calculations. For incident neutrons, the Wilmore-Hodgson
potential was used below 15 MeV, and the Madland potential [Ma88]
was used at higher energies. For incident protons, the
Becchetti-Greenlees [Be69] potential was used up to 50 MeV, above
which the Madland potential [Ma88] was used. In both cases, the
matching energy between the potentials was chosen to result in
continuity of the reaction cross section. For protons at 50 MeV
the reaction cross section (and transmission coefficients) was
renormalized slightly to smoothen the transition between the
potentials. The Perey [Pe63] potential was used for indident
deuterons. For tritons, the Becchetti-Greenlees [Be71] was used
up to 80 MeV, above which the Watanabe potential was used. The
Moyen (McFadden Satchler) [Mc66] potential was used for alpha
particles over the whole energy range.
Direct inelastic scattering to low-lying states in Nb93 was
determined as follows. Coherent excitation of 2+ and 3-
vibrations were assumed to be fragmented over Nb93 states, after
coupling these excitations with the 4.5+ core. The magnitudes of
the deformation lengths of 2+ and 3- excitations was obtained by
fitting values of 34 and 46 mb respectively at 14 MeV, obtained
in ref. [Ch93] and accounting for measurements well. This
strength was then fragmented over Nb states. For the 3-
excitation, the 7 states are in the "continuum" region of the
GNASH calculation at approximately 2.5 MeV, with spins 1.5-,2.5-,
..,7.5-. For the 2+, the 5 states (2.5+,3.5+,...6.5+) near 1 MeV
were assumed to be those whose inelastic cross section in the
existing ENDF <20 MeV file are significant (note that the ENDF
file below 20 MeV appears to incorporate inelastic information
only up to 5 MeV for many states, after which a value of zero at
20 MeV was inserted).
Experimental data is used to benchmark the calculations. For
incident neutrons, experimental neutron emission spectra data
exist at 20 and 26 MeV by Marcinkowski [Ma83]. For incident
protons, spectra data exist at 14 and 26 MeV by Watanabe et
al. [Wa97], and at 65 MeV by Sakai et al [Sa80]. Our evaluation
agrees reasonably well with these measurements.
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REFERENCES
[Be69] F.D. Becchetti, Jr., and G.W. Greenlees, Phys.Rev. 182,
1190 (1969)
[Be71] F.D. Becchetti, Jr., and G.W. Greenlees in Polarization
Phenomena in Nuclear Reactions (Ed: H.H. Barschall and W.
Haeberli, The University of Wisconsin Press, 1971) p.682
[Ch93] M.B. Chadwick and P.G. Young, Phys.Rev. C 47, 2255 (1993)
[Ch96a] M.B. Chadwick, P.G. Young, R.E. MacFarlane, and A.J.
Koning, "High-Energy Nuclear Data Libraries for Accelerator-
Driven Technologies: Calculational Method for Heavy Recoils,"
Proc. of 2nd Int. Conf. on Accelerator Driven Transmutation
Technology and Applications, Kalmar, Sweden, 3-7 June 1996.
[Ch98] M.B. Chadwick and P.G. Young, "Model Calculations of
n,p + 93Nb" in APT PROGRESS REPORT: 1 November 1997 - 1 January
1998, internal Los Alamos National Laboratory memo
January 1998 from R.E. MacFarlane to L. Waters.
[Ch99] M.B. Chadwick, P.G. Young, G.M. Hale et al., Los Alamos
National Laboratory report, LA-UR-99-1222 (1999)
[Co67] J.L. Cook, H. Ferguson, and A.R. DeL Musgrove, Aust.J.
Phys. 20, 477 (1967)
[Fi93] R. W. Finlay, W. P. Abfalterer, G. Fink et al., Phys. Rev
C 47, 237 (1993)
[Ig75] A.V. Ignatyuk, G.N. Smirenkin, and A.S. Tishin, Sov.J.
Nucl.Phys. 21, 255 (1975); translation of Yad.Fiz. 21, 485
(1975)
[Ka77] C. Kalbach, Z.Phys.A 283, 401 (1977)
[Ka85] C. Kalbach, Los Alamos National Laboratory report
LA-10248-MS (1985)
[Ka88] C. Kalbach, Phys.Rev.C 37, 2350 (1988); see also
C. Kalbach and F. M. Mann, Phys.Rev.C 23, 112 (1981)
[Ko90] J. Kopecky and M. Uhl, Phys.Rev.C 41, 1941 (1990)
[Lo74] J.M. Lohr and W. Haeberli, Nucl.Phys. A232, 381 (1974)
[Ma88] D.G. Madland, "Recent Results in the Development of a
Global Medium-Energy Nucleon-Nucleus Optical-Model Potential,"
Proc. OECD/NEANDC Specialist's Mtg. on Preequilibrium Nuclear
Reactions, Semmering, Austria, 10-12 Feb. 1988, NEANDC-245 'U'
(1988).
[Ma83] A. Marcinkowski, R.W. Finlay, G. Randers-Pehrson et al.,
Nucl.Phys. A402, 220 (1983)
[Mc66] L. McFadden and G. R. Satchler, Nucl. Phys. 84, 177
(1966).
[Pe63] C.M. Perey and F.G. Perey, Phys.Rev. 132, 755 (1963)
[Sa80] H. Sakai, K. Hosono, N. Matsuoka et al., Nucl.Phys. A344,
41 (1980)
[We96] H.P. Wellisch and D. Axen, Phys.Rev. C 54, 1329(1996)
[Wa97] Y. Watanabe, S. Yoshioka, M. Harada et al, Nuclear Data
for Science and Technology, Proc. Conf. Trieste, May, 1997,
G. Reffo, Ed. (Editrice Compositori, 1997) p.580
[Wi64] D. Wilmore and P.E. Hodgson, Nucl.Phys. 55, 673 (1964)
[Yo92] P.G. Young, E.D. Arthur, and M.B. Chadwick, report
LA-12343-MS (1992)
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ENDF/B-VI MOD 2 Revision, August 1991, NNDC
Only the section MOD numbers have been corrected in the
directory.
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ENDF/B-VI MOD 1 Evaluation, March 1990, A.B. Smith, D.L. Smith
L.P. Geraldo (ANL), and R. Howerton (LLNL)
Original evaluation fully documented in Smith et al. [1]
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Evaluation of 93Nb(n,n')93Nb-m Dosimetry Reaction
D.L. Smith and L.P. Geraldo, ANL, March 1990.
For complete documentation see Smith and Geraldo [2].
Production of the isomer 93Nb-m by the (n,n') process is
routinely employed for neutron dosimetry applications. Isomer
is the first-excited state of the isotope 93Nb (30.82 keV
excitation energy). The reaction threshold energy is 31.15 keV.
The isotopic abundance of 93Nb in natural niobium is 100 %.
The half life of 93Nb-m is 16.1 years. The decay is entirely by
isomeric transition with nearly 100 % internal conversion.
The activity measurement is by observation of x-rays.
X-ray yields: 16.6 keV k-alpha (0.09238 per disintegration),
18.6 kev k-beta (0.01802 per disintegration).
The evaluation is based on a least-squares adjustment procedure.
Input information includes results from nuclear model
calculations and recent differential activation cross section
data from the literature. Uncertainties are derived from
experimental errors and the consideration of systematics.
REFERENCES
[1.] A.B. Smith, D.L. Smith and R.J. Howerton, Argonne report
ANL/NDM-88 (1985)
[2.] D.L. Smith and L.P. Geraldo, Argonne report ANL/NDM-117
(1990)
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