ENTRY 14808 20230317 1480800000001 SUBENT 14808001 20230317 20231011 1480800100001 BIB 8 26 1480800100002 TITLE Preliminary Determination of the Neutron Absorption 1480800100003 Cross Section of Long-Lived I129 1480800100004 AUTHOR (S.Katcoff) 1480800100005 REFERENCE (J,PR,71,826,1947) 1480800100006 #doi:10.1103/PhysRev.71.826 1480800100007 INSTITUTE (1USALAS) 1480800100008 FACILITY (REAC,1USALAS) The Los Alamos homogeneous pile. 1480800100009 DETECTOR (GEMUC) A mica-window Geiger counter. 1480800100010 METHOD (CHSEP) In the present experiment the previously used 1480800100011 iodine sample was irradiated simultaneously with two 1480800100012 normal iodine samples for 12.8 hours in the Los 1480800100013 Alamos homogeneous pile, just outside the BeO 1480800100014 reflector. Normal iodine, which is known to consist 1480800100015 only of stable I127, should give on slow neutron 1480800100016 irradiation only 25-min. I128. However, the sample 1480800100017 which also contained some I129 yielded several 1480800100018 thousand counts per minute of 12.6-hr. I130 after 1480800100019 irradiation. All three samples were purified 1480800100020 radio-chemically, mounted as AgI, and counted with a 1480800100021 mica-window Geiger counter. Absorption of the 1480800100022 radiations of the 12.5-hr. component in aluminum 1480800100023 indicated two beta-rays with maximum energies of 0.54 1480800100024 and 1.02 MeV. This compares favorably with the values 1480800100025 for I130 reported in the literature of 0.61 and 1.03 1480800100026 MeV. 1480800100027 HISTORY (20230317C) BP 1480800100028 ENDBIB 26 0 1480800100029 COMMON 1 3 1480800100030 EN-DUMMY 1480800100031 EV 1480800100032 0.0253 1480800100033 ENDCOMMON 3 0 1480800100034 ENDSUBENT 33 0 1480800199999 SUBENT 14808002 20230317 20231011 1480800200001 BIB 4 15 1480800200002 REACTION (53-I-129(N,ABS),,SIG,,MXW) 1480800200003 ANALYSIS The first, is based on the fission cross section of 1480800200004 uranium, the fission yield of the chain of mass 129 1480800200005 (0.7%), the weight of uranium, the time of 1480800200006 irradiation, the approximate neutron flux in which 1480800200007 the uranium slug was irradiated, and the assumptions 1480800200008 that about 30% of the iodine in the slug was 1480800200009 extracted and that the chemical yield was also about 1480800200010 30%. This leads to a value of 7.6*10**15 for the 1480800200011 number of I129 atoms and to a value of 2.5 barns 1480800200012 (10**-24 cm2) for the cross section. 1480800200013 ASSUMED (ASSUM,92-U-0(N,F)MASS,CHN,FY) 1480800200014 STATUS (TABLE,,S.Katcoff,J,PR,71,826,1947) 1480800200015 page 826 of J,PR,71,826,1947. 1480800200016 (COREL,14808003) 1480800200017 ENDBIB 15 0 1480800200018 COMMON 1 3 1480800200019 ASSUM 1480800200020 PC/FIS 1480800200021 0.7 1480800200022 ENDCOMMON 3 0 1480800200023 DATA 1 1 1480800200024 DATA 1480800200025 B 1480800200026 2.5 1480800200027 ENDDATA 3 0 1480800200028 ENDSUBENT 27 0 1480800299999 SUBENT 14808003 20230317 20231011 1480800300001 BIB 4 13 1480800300002 REACTION (53-I-129(N,ABS),,SIG,,MXW) 1480800300003 ANALYSIS The other method of estimation is based on an 1480800300004 approximate measurement of the 8.0-day I131 activity 1480800300005 which was present at the end of the 123-day 1480800300006 irradiation in the iodine sample. This assumes that 1480800300007 the bombardment of the uranium was steady, especially 1480800300008 near the end. The fission yield of I131 was taken as 1480800300009 2.5%. This leads to a value of 1.9*10**15 I129 atoms 1480800300010 and to a value of 10 barns for the cross section. 1480800300011 ASSUMED (ASSUM,92-U-0(N,F)53-I-131,CUM,FY) 1480800300012 STATUS (TABLE,,S.Katcoff,J,PR,71,826,1947) 1480800300013 page 826 of J,PR,71,826,1947. 1480800300014 (COREL,14808002) 1480800300015 ENDBIB 13 0 1480800300016 COMMON 1 3 1480800300017 ASSUM 1480800300018 PC/FIS 1480800300019 2.5 1480800300020 ENDCOMMON 3 0 1480800300021 DATA 1 1 1480800300022 DATA 1480800300023 B 1480800300024 10.0 1480800300025 ENDDATA 3 0 1480800300026 ENDSUBENT 25 0 1480800399999 ENDENTRY 3 0 1480899999999