Back
2-He- 3 LANL EVAL-MAY90 G.HALE, D.DODDER, P.YOUNG
DIST-JAN09 20090105
----JEFF-311 MATERIAL 225
-----INCIDENT NEUTRON DATA
------ENDF-6 FORMAT
*************************** JEFF-3.1.1 *************************
** **
** Original data taken from: JEFF-3.1 **
** **
******************************************************************
***************************** JEFF-3.1 *************************
** **
** Original data taken from: JEFF-3.0 **
** **
******************************************************************
***************************** JEFF-3.0 *************************
DATA TAKEN FROM :- ENDF/B-VI.3 (DIST-SEP91 REV1-JUL91)
******************************************************************
MOD1 OF ENDF/B-VI
THE ONLY REVISION MADE FOR MOD1 OF ENDF/B-VI WAS TO ADD THE
COMMENTS BELOW ON THE STANDARDS COVARIANCES. THE DESCRIPTION
OF THE ENDF/B-VI EVALUATION IS GIVEN BELOW.
*****************************************************************
----------------------------------------------------------------
HE-3 FREE ATOM EVALUATION
ENDF/B-VI DESCRIPTION
----------------------------------------------------------------
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
this file transfered from l.stewart's endf/b-iii evaluation with
modifications only in the 3he(n,p) and the elastic cross sections
below 5 MeV, and the total cross section below 0.1 MeV.
* * * * * * *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* *
* cross section standard he-3 (n,p) *
* *
* the he-3 (n,p) cross section for this material is recommended
* as a standard for neutron energies from thermal to 50 kev
* *
* * * * * * *
mf=1
mt=451, atomic mass=3.0160
mf=2
mt=151, scattering length=0.2821e-12 cm.
mf=3
mt= 1, total cross sections --- from .00001 ev to 200 kev
mt1 taken as sum mt2+mt102+mt103. from 200 kev to 20
mev, mt1 evaluated using experimental data from ref.6.
mt= 2, elastic scattering cross sections --- from .00001 ev
to 200 kev, mt2 taken approximately from r-matrix
analysis described below. above 200 kev, obtained
from mt2=mt1-mt102-mt103-mt104. note two reactions
missing from this evaluation, namely n,n-prime,p and
n,2n,2p. exp. data at 15 mev indicates non-zero
cross sections for these. included in mt2 this eval.
mt=102, radiative capture cross sections --- thermal value
taken from ref.17, with assumption of 1/v energy
energy variation at all other energies.
mt=103, n-p cross sections --- below 5 mev taken from an
r-matrix calculation of the four-body reactions
by hale and dodder. 3he(n,p) data included were
from refs. 5,13,14, and 15. for energies in the
5-20 mev range, data were used as follows -
ref.4 - 5.8 mev to 11. mev
ref.10- 5.0 mev to 11. mev
ref.12- 5.0 mev to 12. mev
ref.16- 14. mev
data extrapolated to 20. mev.
mt=104, n-d cross sections --- threshold=4.36147mev
q=-3.2684 mev. evaluation from a detailed balance
calculation(ref.13) and experimental data(ref.11).
mt=251, average value of cosine of elastic scattering angle,
laboratory system. obtained from data mf=4,mt=2.
mt=252, values of xi, obtained from data mf=4,mt=2
mt=253, values of gamma,obtained from data mf=4,mt=2
mf=4
mt= 2, angular distribution of secondary neutrons from
elastic scatter. evaluated from experimental data
from refs.2,7,9,11,16,17 covering incident energies
as follows -
incident energy references
1.e-5ev (isotropic)
0.5 mev (isotropic)
1.0 mev 9
2.0 mev 9
2.6 mev 11
3.5 mev 9
5.0 mev 11
6.0 mev 9,7(from p+t elastic scatt)
8.0 mev 11,7(from p+t elastic scatt)
14.5 mev 16,17(from p+t elastic scatt)
17.5 mev 11
20.0 mev 2(from p+t elastic scatt)
references
1. r.batchelor,r.aves,and t.h.r.skyrme,rev.sci.instr.26,1037
(1955).
2. r.a.vanetsian and e.d.fenchenko,soviet journal of atomic
energy 2,141(1957).
3. j.n.bradbury and l.stewart,bull.am.phys.soc.3,417(1958)
4. g.f.bogdanov,n.a.vlasov,c.p.kalinin,b.v.rybakov,l.n.
samoilov,and v.a.sidorov,jetp(ussr)36,633(1959).
5. j.h.gibbons and r.l.macklin,phys.rev.114,571(1959).
6. los alamos physics and cryogenics groups,nucl.phys.12,
291(1959).
7. j.e.brolley,jr.,t.m.putnam,l.rosen,and l.stewart,phys.
rev.159,777(1967).
8. j.e.perry,private communication to stewart(1960)
9. j.d.seagrave,l.cranberg,and j.e.simmons,phys.rev.119,
1981(1960)
10. m.d.goldberg,j.d.anderson,j.p.stoering,and c.wong,phys.
rev.122,1510(1961).
11. a.r.sayers,k.w.jones,and c.s.wu,phys.rev.122,1853(1961).
12. w.e.wilson,r.l.walter,and d.b.fossan,nucl.phys.27,421
(1961).
13. j.als-nielsen and o.dietrich,phys.rev.133,b925(1964).
14. r.l.macklin and j.h.gibbons,proceedings of the internatl.
conf.on the study of nucl.struct.with neuts.,antwerp(1965)
15. j.h.gibbons,private communication to stewart(1966).
16. b.antolkovic,g.paic,p.tomas,and r.rendic,phys.rev.159,
777(1967).
17. l.rosen and w.leland,private communication(1967)
18. s.mughabghab et al., neut.cross sect., vol.1, neut.reson.
parameters and thermal cross sect., academic pr.(1981).
****************************************************************
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 He-3(n,p) cross section are as
follows:
Energy Range Estimated Uncertainty
(keV) (percent)
1.0E-08 - 0.1 0.3
0.1 - 1.0 0.7
1.0 - 10. 2.0
10. - 50. 5.0
****************************************************************
Back
|
