ENTRY 22867 20050221 21722286700000001
SUBENT 22867001 20050221 21722286700100001
BIB 13 46 2286700100002
TITLE .s-process branching at 185W revised. 2286700100003
AUTHOR (P.MOHR,T.SHIZUMA,H.UEDA,S.GOKO,A.MAKINAGA,K.Y.HARA, 2286700100004
T.HAYAKAWA,Y.-W.LUI,H.OHGAKI,H.UTSUNOMIYA) 2286700100005
INSTITUTE (2GERTHD,2JPNJAE,2JPNKON,1USATAM,2JPNKTO,2JPNJPN) 2286700100006
REFERENCE (J,PR/C,69,032801,2004) 2286700100007
FACILITY (ESTRG,2JPNAIS) Electron storage ring TERAS at AIST 2286700100008
(Tsukuba, Japan). 2286700100009
INC-SOURCE (MPH,LASER) Tunable monochromatic photon source from 2286700100010
laser Compton scattering - Laser Compton Scattering 2286700100011
photons, LCS. 2286700100012
DETECTOR (HE3SP) Improved neutron detector consisted of 16 2286700100013
individual 3He counters embedded in two rings in a 2286700100014
poliethilene moderator. 2286700100015
METHOD (RINGR) Direct measurement of photoneutrons using the 2286700100016
ring-ratio method: ring-ratio between the count 2286700100017
rates of the inner and outer detector rings depends 2286700100018
on the neutron energy, and hence cfn be used to 2286700100019
estimate the neutron energy. That varied between 2.5 2286700100020
and 4.4 leading to average neutron energies of about 2286700100021
1.2 MeV at highest photon energies and of about 0.3 2286700100022
MeV at lower photon energies. 2286700100023
SAMPLE The target consisted of 1246 mg metallic tungsten 2286700100024
powder highly enriched in 186W to 99.79 % The powder 2286700100025
was pressed to a small self-supporting tablet with a 2286700100026
diameter of 8 mm. 2286700100027
ANALYSIS (UNFLD) For estimation of the reaction cross section 2286700100028
from the experimental reaction yield the unfolding 2286700100029
procedure using the replacement of integral eguation 2286700100030
by Taylor series (because the difference (low-energy 2286700100031
tail) of realistic photon spectrum from ideal is 2286700100032
relatively small) was used. 2286700100033
ERR-ANALYS Statistical errors. 2286700100034
COMMENT The neutron capture cross section of the unstable 2286700100035
s-process branching nucleus 185W has been derived 2286700100036
from experimental data of inverse 186W(g,n)185W 2286700100037
photodisintegration taken with monochromatic photon 2286700100038
beams from laser Compton scattering. The result of 2286700100039
SIG = 553 (60) mb at kT = 30 keV leads to a 2286700100040
relatively high effective neutron density in the 2286700100041
classical s-process of Nn = 4.7 x 10**8 sm**-3. A 2286700100042
realistic model for the s-process in thermally 2286700100043
pulsing asymptotic giant branch stars overestimates 2286700100044
the abundance of 186Os significantly because of the 2286700100045
relatively small neutron capture cross section of 2286700100046
185W. 2286700100047
HISTORY (20050118C) V.V./S.M. 2286700100048
ENDBIB 46 0 2286700100049
NOCOMMON 0 0 2286700100050
ENDSUBENT 49 0 2286700199999
SUBENT 22867002 20050221 21722286700200001
BIB 3 4 2286700200002
REACTION (74-W-185(N,G)74-W-186,,SIG,,MXW) 2286700200003
INC-SPECT .Quasi-maxwellian energy spectrum 2286700200004
STATUS (CURVE) The data from Fig. 3 have been digitized at 2286700200005
the Russia MSU SINP CDFE by V.V.Varlamov. 2286700200006
ENDBIB 4 0 2286700200007
NOCOMMON 0 0 2286700200008
DATA 3 1 2286700200009
KT DATA ERR-S 2286700200010
KEV MB MB 2286700200011
30. 553. 60. 2286700200012
ENDDATA 3 0 2286700200013
ENDSUBENT 12 0 2286700299999
ENDENTRY 2 0 2286799999999