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3-Li - 6 LANL EVAL-APR89 G.M.HALE, P.G.YOUNG
DIST-JAN09 20090105
----JEFF-311 MATERIAL 325
-----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: JEFF-3.0 **
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***************************** JEFF-3.0 *************************
DATA TAKEN FROM :- ENDF/B-VI.3 (DIST-SEP91 REV1-JUL91)
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MOD1 OF ENDF/B-VI
The following revisions were made for MOD1 of ENDF/B-VI:
1. MF=1,MT=451 - Comments were added regarding estimated
(expanded) covariance for the Standards Cross Sections.
2. MF=3,MT=53 - LF flag and Q-value corrected.
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ENDF/VI EVALUATION
G. M. Hale and P. G. Young
MAJOR CHANGES FROM VERSION V OF ENDF/B ARE:
1. Inclusion of the ENDF/B-VI standard (n,t) cross section
from the simultaneous standards analysis (ca85) over the
energy range thermal to 1 MeV.
2. Replacement of all major cross sections and elastic angular
distributions at energies between 10^-5 eV and 3 MeV with
results from the R-matrix analysis performed in conjunction
with the simultaneous standards analysis.
3. Revision of the elastic cross sections and angular distri-
butions at energies between 3 and 20 MeV to match recent
experimental data, resulting in a general decrease of the
elastic cross section in this energy range.
4. Revision of the (n,n')d cross sections to account for
recent measurements, resulting in a general increase in
the total (n,n')d cross section that tends to offset the
decrease in the elastic cross section and maintain about
the same total cross section as before.
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STANDARDS COVARIANCES
Phase 1 reviewers of the ENDF/B-VI standards cross sections have
expressed the concern that the uncertainties resulting from the
combination of R-matrix and simultaneous evaluations might have
led to uncertainties that are too small. As a result, the
Standards Subcommittee produced (at the May, 1990 CSEWG meeting)
a set of expanded covariance estimates for the standard cross
section reactions. These uncertainties are estimates such that
if a modern day experiment were performed on a given standard
cross section using the best techniques, approximately 2/3 of
the results should fall within these expanded uncertainties. The
expanded uncertainties for the Li-6(n,t) cross section are given
in the following table and are compared to values from the
combined output of the standards covariance analysis:
Energy Range Estimated Uncertainty Combined Analysis
(keV) (percent) (percent)
1.0E-08 - 0.1 0.3 0.14
0.1 - 1.0 0.5
1.0 - 10. 0.7 0.14
10. - 50. 0.9
50. - 90. 1.1 0.25
90. - 150 1.5
150 - 450 2.0 0.29
450 - 650 5.0
650 - 800 2.0 0.36
800 - 1000 5.0
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mf=2 --------- resonance parameters ----------------------------
mt=151 effective scattering radius = 2.31175e-13 cm.
mf=3 --------- smooth cross sections ---------------------------
the 2200 m/s cross sections are as follows:
mt=1 sigma = 941.6928 barns
mt=2 sigma = 0.67157 barns
mt=102 sigma = 0.03850 barns
mt=105 sigma = 940.9827 barns
mt=1 total cross section
below 3 mev, the values are taken from an r-matrix
analysis by hale, dodder, and witte (ha84) which takes
into account data from all reactions possible in 7li
up to 4 mev neutron energy. total cross section data
considered in this analysis were those of ha75 and sm77.
between 3 and 20 mev, the total was taken to be the
sum of mt=2,4,24,102,103, and 105, which generally
follows the measurements of sm82, ke79, kn77, go72,
and fo71.
mt=2 elastic cross section
below 3 mev, the values are taken from the r-matrix
analysis cited for mt=1, which includes the elastic
measurements of sm82 and la61. above 3 mev, the curve
is a smooth representation of the data of kn79 and ba63
up to 7.5 mev, and of that of ho79 between 7.5 and 13
mev. the curve passes through the average of several
measurements at 14 mev, and is extrapolated to 20 mev
using the shape of an optical model calculation.
mt=4 total inelastic cross section
sum of mt=51 through mt=81.
mt=24 (n,2n)alpha cross section
passes through the point of mather and paine (ma69) at
14 mev, taking into account the measurements of as63.
mt=51,52,54-56,58-81 (n,n')d continuum
represented by continuum-level contributions in 6li,
binned in .5-mev intervals. The energy-angle spectra
are determined by a 3-body phase-space calculation,
assuming isotropic center-of mass distributions. at
each energy, the sum of the continuum-level
contributions is normalized to an assumed energy-angle
integrated continuum cross section which approximates
the difference of the nonelastic sigma and the
contribution from the first and second levels in 6li.
the steep rise of the pseudo-level cross sections from
their thresholds and the use of fixed bin widths over
finite angles produces anomolous structure in the
individual cross sections which is especially apparent
near the thresholds. some effort has been made to
smooth out these effects, but they remain to some
extent.
mt=53 (n,n1)d discrete level cross section
has p-wave penetrability energy dependence from threshold
to 3.2 mev. matched at higher energies to a curve
through fitted legendre coefficients from experimental
data of sa82, ho79, sm80, ho68, ba63.
mt=57 (n,n2)gamma cross section
is based on the available experimental data, especially
that of ho79, li80, sm82, ho68.
gradually to 20 mev. smooth curve drawn through data
of pr69 and be75.
mt=102 (n,gamma) cross section
unchanged from version v, which was based on the thermal
measurement of jurney (ju73) and the pendlebury
evaluation (pe64) at higher energies.
mt=103 (n,p) cross section
threshold to 9 mev, based on the data of ba65.extended to
20 mev through the 14 mev data of fr54 and ba53.
mt=105 (n,t) cross section
below 3 mev, values are taken from the r-matrix analysis,
which includes (n,t) measurements from re78, la78, br77,
ov74, and ba75. between 3 and 5 mev, the values are
based on ba75, and at higher energies are taken from the
evaluation of pe64, extended to 20 mev considering the
data of ke58.
mf = 4-------------------angular distributions-------------------
mt=2 elastic cross section
legendre coefficients determined as follows:
below 4 mev, coefficients up to l=6 were taken from
the r-matrix analysis , which included the measurements
la61 and sm 82. above 4 mev, the coefficients represent
fits to the measurements of ho68, ho79, kn79, sm82,
de73, ba63, ab70, and hy68. most emphasis was placed
on the data of ho79, kn79, sm82. extrapolation of the
coefficients to 20 mev was aided by optical model
calculations.
mt=24 (n,2n) cross section
lab distributions obtained by integrating over energy the
4-body phase-space spectra that result from transforming
isotropic center-of-mass distributions to the laboratory
system.
mt=51-81 (n,n')d cross sections
excitation energy binned data is assumed isotropic in the
center of mass reference system. mt = 53 and 57
are real levels. mt = 57 is assumed to be isotropic
in the two-body reference system. mt = 53 is given as
anisotropic, based on fits of legendre expansions to
the experimental data of ab70, ba63, ho68, ho79, me65,
hy68, wo62, sa82.
mt=105 (n,t).cross section (to be added)
legendre coefficients obtained from the r-matrix analysis
are supplied at energies below 4 mev. the analysis
takes into account (n,t) angular distribution
measurements from kn83, co82, dr82, br77, ba75, and
ov74.
mf = 5---------secondary energy distributions--------------------
mt=24 (n,2n)
lab distributions obtained by integrating over angle the 4-
body phase-space spectra that result from transforming
isotropic center-of-mass distributions to the laboratory
system.
mf = 12--------gamma-ray multiplicities--------------------------
mt=57 (n,n2) gamma
energy taken from aj74. multiplicity assumed to be one.
mt=102 (n,gamma)
energies and transition arrays for radiative capture taken
from ju73, as reported in aj74. the lp flag was used to
describe the mt=102 photons.
mf = 14--------gamma-ray angular distributions-------------------
mt=57 (n,n2)gamma
the gamma is assumed isotropic.
mt=102 (n,gamma)
.the two high-energy gammas are assumed isotropic. data on
the 477 kev gamma indicate isotropy.
mf=33----------cross section covariances-------------------------
(to be added later)
the relative covariances for mt=1,2, and 105 below 4 mev are
given in file 33. they are based on calculations using the co-
variances of the r-matrix parameters in first-order error
propogation.
mt=1 total
relative covariances entered as nc-type sub-subsection,
implying that they are to be constructed from those for
mt=2 and 105. they are not intended for use at energies
above 4 mev.
mt=2,105 elastic and (n,t)
relative covariances among these two cross sections are
entered explicitly as ni-type sub-subsections in the
lb=5 (direct) representation at energies below 4 mev.
although values for the 3.95-4.05 mev bin are repeated
in a 4-20 mev bin, the covariances are not intended for
use at energies above 4 mev.
--------------------- references --------------------------------
ab70 U.Abbondanno, Nuo.Cim. A166,139(1970).
aj74 f.ajzenberg-selove and t.lauritsen, nucl. phys. a227,55
(1974).
ar64 a.h.armstrong, j.gammel, l.rosen, and g.m.frye, nucl. phys.
52,505 (1964).
as63 v.j.ashby et al, phys. rev. 129,1771 (1963).
ba53 m.e.battat and f.l.ribe, phys.rev. 89,80 (1953).
ba63 r.batchelor and j.h.towle, nucl. phys. 47,385 (1963).
ba65 r.bass, c.bindhardt, and k.kruger, eandc(e)-57u (1965).
ba75 c.m.bartle, proc. conf. on nuclear cross sections and
technology, vol.2,688 (1975), and private communication
(1976). see also nucl. phys. a330, 1 (1979).
be75 besotosnyj et al., yk-19, 77 (1975).
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16c, 513 (1977).
ca85 a.d.carlson,w.p.poenitz,g.m.hale, and r.w.peele, nuclear
data for basic and applied science (santa fe, n.m.), 1429
(1985).
co67 j.a.cookson and d.dandy, nucl. phys. a91,273 (1967).
co82 h.conde,t.andersson,l.nilsson, and c.nordborg, nuclear data
for science and technology (antwerp, belgium), 447 (1982).
de73 F.Demanins et al., infn/be-73 (1973).
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(1982).
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ha75 j.a.harvey and n.w.hill, nuclear cross sections and
technology (washington, d.c.), 244 (1975).
ha84 g.m.hale, nuclear standard reference data (geel,belgium)
iaea tecdoc-335, 103 (1984). describes preliminary analysis.
ho68 j.c.hopkins,d.m.drake, and h.conde, nucl. phys. a107,139
(1968), and j.c.hopkins, d.m.drake, and h.conde, la-3765
(1967).
ho79 h.h.hogue et al., n.s.&e. 69, 22 (1979).
ju73 e.t.jurney, lasl, private communication (1973).
ke58 r.d.kern and w.e.kreger, phys. rev. 112, 926 (1958).
ke79 j.d.kellie,g.p.lamaze, and r.b.schwartz, nuclear cross
sections for technology (knoxville, tn.), 48 (1979).
kn77 h.h.knitter,c.budtz-jorgensen,m.mailly, and r.vogt, eur-
5726e (1977).
kn79 h.d.knox,r.m.white, and r.o.lane, n.s.&e. 69, 223 (1979).
kn83 h.h.knitter,c.budtz-jorgensen,d.l.smith, and d.marletta,
n.s.&e. 83, 229(1983).
la61 r.o.lane,a.s.langsdorf,j.e.monahan, and a.j.elwyn, ann.
phys.12, 135 (1961).
la78 g.p.lamaze,o.a.wasson,r.a.schrack, and a.d.carlson, n.s.&e.
68, (1978).
li80 p.w.lisowski et al., la-8342 (1980).
ma69 d.s.mather and l.f.paine, awre-o-47/69 (1969).
me65 f.merchez,n.v.sen,v.regis, and r.bouchez, compt. rend. 260,
3922 (1965).
ov74 j.c.overley,r.m.sealock, and d.h.ehlers, nucl. phys. a221,
573 (1974).
pe64 e.d.pendlebury, awre-o-60/64 (1964).
pr69 g.presser et al., nuc.phys. a131, 679(1969).
re78 c.renner,j.a.harvey,n.w.hill,g.l.morgan, and k.pusk, bull.
am. phys. soc. 23, 526 (1978).
sa82 e.t.sadowski,h.knox,d.a.resler, and r.o.lane, bap 27,624(c5)
(1982).
sm77 a.b.smith,p.guenther,d.havel, and j.f.whalen, anl/ndm-29
(1977).
sm82 a.b.smith,p.t.guenther, and j.f.whalen, nucl. phys. a373,
305 (1982).
wo62 c.wong,j.d.anderson, and j.w.mcclure, nucl. phys. 33,680
(1962).
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