ENTRY 21730 20230403 231721730 0 1 SUBENT 21730001 20230403 231721730 1 1 BIB 12 35 21730 1 2 TITLE Precise determination of the branching ratio and 21730 1 3 Q-value of the B-10(n,alpha)Li-7 reaction and of the 21730 1 4 Q-value of the Li-6(n,alpha)H-3 reaction 21730 1 5 AUTHOR (A.J.Deruytter,P.Pelfer) 21730 1 6 REFERENCE (J,JNE,21,833,1967) Full report. 21730 1 7 (P,EANDC(E)-76,140,1967) Progress rept, superseded. 21730 1 8 INSTITUTE (2ZZZGEL) C.B.N.M. Geel. 21730 1 9 FACILITY (REAC,2ZZZGEL) BR-1 reactor 21730 1 10 INC-SOURCE (REAC) Thermal neutron beam extracted from the 21730 1 11 graphite reflector, intensity 10*6 n/cm2/sec. 21730 1 12 Cadmium ratio values were determined with and without 21730 1 13 a 0.4 mm thick cadmium foil. 21730 1 14 INC-SPECT Thermal Maxwellian neutron spectrum, with correction 21730 1 15 made for an epi-cadmium plus room background 21730 1 16 intensity equal to 2.80+-0.02% of the incident beam. 21730 1 17 SAMPLE A thin elemental layer of B-10, 15 ug/cm2, with 21730 1 18 a diameter of 38 mm, prepared by evaporation on a gold21730 1 19 coated quartz disk, and mounted in a vacuum chamber a 21730 1 20 at 30 mm from the sensitive surface of the detector. 21730 1 21 METHOD (ASSOP) Detection of emitted alphas. Good separation 21730 1 22 of the two alpha peaks allows the sum of counts under 21730 1 23 each peak to be considered proportional to the two 21730 1 24 partial cross sections to the Li-7 ground and first 21730 1 25 excited states. 21730 1 26 DETECTOR (SIBAR) Gold silicon surface barrier detector, 400 mm2 21730 1 27 in area. The detector was outside the direct beam but 21730 1 28 parallel to the source. 21730 1 29 The detector was operated at a reverse bias of 20 V, 21730 1 30 giving a depletion depth of 55 um, sufficient to 21730 1 31 stop all reaction products of B-10(n,alpha) but thin 21730 1 32 enough to limit pile up of background pulses. 21730 1 33 STATUS (TABLE) Text on p.838 from J.Nucl.Energy,21(1967)833 21730 1 34 HISTORY (19810130C) 21730 1 35 (20230403A) SD:Updated to new date formats,lower case. 21730 1 36 Corrections in all Subents. 21730 1 37 ENDBIB 35 0 21730 1 38 NOCOMMON 0 0 21730 1 39 ENDSUBENT 38 0 21730 199999 SUBENT 21730002 20230403 231721730 2 1 BIB 4 15 21730 2 2 REACTION ((5-B-10(N,A)3-LI-7,PAR,SIG)// 21730 2 3 (5-B-10(N,A)3-LI-7,PAR,SIG)) 21730 2 4 the branching ratio defined as sig(n,a(0))/sig(n,a(1))21730 2 5 given in the text as percent, but converted here into 21730 2 6 an absolute ratio. 21730 2 7 CORRECTION Corrected for epithermal neutrons. The measured 21730 2 8 reactor spectrum value was 6.741+-0.006%, and the 21730 2 9 epicadmium value was 7.02+-0.08%. With the measured 21730 2 10 cadmium ratio of the spectrum the value for epithermal21730 2 11 neutrons and room background neutrons is given. 21730 2 12 ERR-ANALYS (DATA-ERR) The uncertainty is one standard deviation, 21730 2 13 primarily from statistical counting uncertainties. 21730 2 14 The supplementary error from background was an order 21730 2 15 of magnitude smaller. 21730 2 16 HISTORY (20230403A) SD: REACTION code updated. ERR-T->DATA-ERR.21730 2 17 ENDBIB 15 0 21730 2 18 NOCOMMON 0 0 21730 2 19 DATA 5 1 21730 2 20 EN LVL-NUM-NM LVL-NUM-DN DATA DATA-ERR 21730 2 21 EV NO-DIM NO-DIM NO-DIM NO-DIM 21730 2 22 2.53E-02 0. 1. 6.733E-02 7.00E-05 21730 2 23 ENDDATA 3 0 21730 2 24 ENDSUBENT 23 0 21730 299999 ENDENTRY 2 0 2173099999999