ENTRY M0441 20170127 M087M044100000001 SUBENT M0441001 20170127 M087M044100100001 BIB 12 47 M044100100002 TITLE Precision measurement of the Be-9(gamma,n) cross M044100100003 section. M044100100004 AUTHOR (J.H.Gibbons,R.L.Macklin,J.B.Marion,H.W.Schmidt) M044100100005 REFERENCE (J,PR,114,1319,1959) M044100100006 INSTITUTE (1USAORL) M044100100007 METHOD (INTB) A g-ray source (Sb or Y) was inserted in the M044100100008 beryllium shell and carefully mounted in a central M044100100009 position. M044100100010 SAMPLE The beryllium sample was in form of spherical shell M044100100011 of inner radius r1 = 15.31 mm and of outer radius r2 M044100100012 = 16.81 mm (shell thickness t = 1.5 mm). The shell M044100100013 was found to Be spherical and of uniform thickness M044100100014 to within 0.005 mm. The mass of the shell was 8.838 M044100100015 g. M044100100016 DETECTOR (BF3) The neutron detector assembly consisted of BF3 M044100100017 counters embedded in a 5-foot diameter graphite M044100100018 sphere moderator. M044100100019 ANALYSIS Counting statistics of 1% were obtained and then the M044100100020 Be shell was removed for the background count. The M044100100021 true-counts-to-background ratio was approximately M044100100022 7:1 for the y case and 70:1 for the Sb source. M044100100023 ERR-ANALYS (ERR-T) The errors given for cross section values are M044100100024 root-mean-square uncertainties calculated taken into M044100100025 account all corrections. M044100100026 Common uncertainties: M044100100027 (ERR-1) gamma-ray source strength; M044100100028 (ERR-2) purity of g-ray source; M044100100029 (ERR-3) neutron detector dead time; M044100100030 (ERR-4) flatness of detector sensitivity; M044100100031 (ERR-5,0.0,0.1) finite source size; M044100100032 (ERR-6,0.0,0.1) attenuation of g-ray in Be shell; M044100100033 (ERR-7) geometry of Be shell and position of M044100100034 g-ray source; M044100100035 (ERR-8) absolute source strength of NBS N2 Sb-g-Be M044100100036 neutron source. M044100100037 COMMENT The present method of measuring the Be-9 photoneutron M044100100038 cross section using radioactive sources Y-89 (1.85 M044100100039 MeV) and Sb-124 (1.69 MeV) is capable of M044100100040 considerably higher precision than techniques M044100100041 previously used. M044100100042 STATUS (TABLE) Data for common uncertainties from tables 1 M044100100043 and 2. M044100100044 HISTORY (19910218C) M044100100045 (20170127A) Corrected by V.Varlamov: dates, STATUS, M044100100046 ERR-ANALYS, COMMON, PART-DET deleted, REACTION, M044100100047 SUBENT 002 separated into SUBENTS 002 and 003, M044100100048 lowercase. M044100100049 ENDBIB 47 0 M044100100050 COMMON 6 3 M044100100051 ERR-1 ERR-2 ERR-3 ERR-4 ERR-7 ERR-8 M044100100052 PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT M044100100053 4.0 1.0 0.6 0.3 0.2 2.0 M044100100054 ENDCOMMON 3 0 M044100100055 ENDSUBENT 54 0 M044100199999 SUBENT M0441002 20170127 M087M044100200001 BIB 6 19 M044100200002 REACTION (4-BE-9(G,X)0-NN-1,,SIG) M044100200003 INC-SOURCE (MPH=(39-Y-89(0,G))). Eg = 1.85 MeV. M044100200004 ERR-ANALYS Individual uncertainties for energy 1.85 MeV: M044100200005 (ERR-S) counting statistics; M044100200006 (ERR-9,0.0,0.1) half life of 88Y; M044100200007 (ERR-10) Compton scattering in source volume; M044100200008 (ERR-11) Compton scattering in source holder; M044100200009 (ERR-12) effect of 2.76 MeV g-ray. M044100200010 CORRECTION Some kinds of corrections to the data were used. M044100200011 These were corrections for: M044100200012 - neutron counter dead-time; M044100200013 - finite source-size; M044100200014 - compton scattering of g-quanta in the source; M044100200015 - g-ray attenuation in the Be shell; M044100200016 - nonuniform activation of the antimony sphere; M044100200017 - effect of the 2.76 MeV g-rays in the Y-89 spectrum; M044100200018 STATUS (TABLE) Data from table 1. M044100200019 HISTORY (20170127A) Corrected by V.Varlamov: REACTION, STATUS, M044100200020 ERR-T. M044100200021 ENDBIB 19 0 M044100200022 COMMON 4 3 M044100200023 ERR-S ERR-10 ERR-11 ERR-12 M044100200024 PER-CENT PER-CENT PER-CENT PER-CENT M044100200025 4.0 1.0 0.6 0.3 M044100200026 ENDCOMMON 3 0 M044100200027 DATA 3 1 M044100200028 EN DATA ERR-T M044100200029 MEV MB MB M044100200030 1.85 .654 .031 M044100200031 ENDDATA 3 0 M044100200032 ENDSUBENT 31 0 M044100299999 SUBENT M0441003 20170127 M087M044100300001 BIB 6 21 M044100300002 REACTION (4-BE-9(G,X)0-NN-1,,SIG) M044100300003 INC-SOURCE (MPH=(51-SB-124(0,G))). Eg = 1.69 MeV. M044100300004 ERR-ANALYS Individual uncertainties for energy 1.69 MeV: M044100300005 (ERR-S) counting statistics; M044100300006 (ERR-9) half-life of 124Sb; M044100300007 (ERR-10) Compton scattering in source; M044100300008 (ERR-11) branching ratio of 124Sb decay; M044100300009 (ERR-12) effect of 2.09 MeV g-ray; M044100300010 (ERR-13,0.0,0.1) nonuniform activation of source. M044100300011 CORRECTION Some kinds of corrections to the data were used. M044100300012 These were corrections for: M044100300013 - neutron counter dead-time; M044100300014 - finite source-size; M044100300015 - compton scattering of g-quanta in the source; M044100300016 - g-ray attenuation in the Be shell; M044100300017 - nonuniform activation of the antimony sphere; M044100300018 - branching ratio of the Sb-124 decay; M044100300019 - effect of the 2.09 MeV g-ray in the Sb-124 spectrum.M044100300020 STATUS (TABLE) Data from table 2. M044100300021 HISTORY (20170127C) Data were compiled at the Russia MSU SINP M044100300022 CDFE by V.Varlamov. M044100300023 ENDBIB 21 0 M044100300024 COMMON 5 3 M044100300025 ERR-S ERR-9 ERR-10 ERR-11 ERR-12 M044100300026 PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT M044100300027 0.7 0.3 0.5 2.5 1.0 M044100300028 ENDCOMMON 3 0 M044100300029 DATA 3 1 M044100300030 EN DATA ERR-T M044100300031 MEV MB MB M044100300032 1.69 1.262 .069 M044100300033 ENDDATA 3 0 M044100300034 ENDSUBENT 33 0 M044100399999 ENDENTRY 3 0 M044199999999