ENTRY 14808 20230317 150614808000 1 SUBENT 14808001 20230317 150614808001 1 BIB 8 26 14808001 2 TITLE Preliminary Determination of the Neutron Absorption 14808001 3 Cross Section of Long-Lived I129 14808001 4 AUTHOR (S.Katcoff) 14808001 5 REFERENCE (J,PR,71,826,1947) 14808001 6 #doi:10.1103/PhysRev.71.826 14808001 7 INSTITUTE (1USALAS) 14808001 8 FACILITY (REAC,1USALAS) The Los Alamos homogeneous pile. 14808001 9 DETECTOR (GEMUC) A mica-window Geiger counter. 14808001 10 METHOD (CHSEP) In the present experiment the previously used 14808001 11 iodine sample was irradiated simultaneously with two 14808001 12 normal iodine samples for 12.8 hours in the Los 14808001 13 Alamos homogeneous pile, just outside the BeO 14808001 14 reflector. Normal iodine, which is known to consist 14808001 15 only of stable I127, should give on slow neutron 14808001 16 irradiation only 25-min. I128. However, the sample 14808001 17 which also contained some I129 yielded several 14808001 18 thousand counts per minute of 12.6-hr. I130 after 14808001 19 irradiation. All three samples were purified 14808001 20 radio-chemically, mounted as AgI, and counted with a 14808001 21 mica-window Geiger counter. Absorption of the 14808001 22 radiations of the 12.5-hr. component in aluminum 14808001 23 indicated two beta-rays with maximum energies of 0.54 14808001 24 and 1.02 MeV. This compares favorably with the values 14808001 25 for I130 reported in the literature of 0.61 and 1.03 14808001 26 MeV. 14808001 27 HISTORY (20230317C) BP 14808001 28 ENDBIB 26 0 14808001 29 COMMON 1 3 14808001 30 EN-DUMMY 14808001 31 EV 14808001 32 0.0253 14808001 33 ENDCOMMON 3 0 14808001 34 ENDSUBENT 33 0 1480800199999 SUBENT 14808002 20230317 150614808002 1 BIB 4 15 14808002 2 REACTION (53-I-129(N,ABS),,SIG,,MXW) 14808002 3 ANALYSIS The first, is based on the fission cross section of 14808002 4 uranium, the fission yield of the chain of mass 129 14808002 5 (0.7%), the weight of uranium, the time of 14808002 6 irradiation, the approximate neutron flux in which 14808002 7 the uranium slug was irradiated, and the assumptions 14808002 8 that about 30% of the iodine in the slug was 14808002 9 extracted and that the chemical yield was also about 14808002 10 30%. This leads to a value of 7.6*10**15 for the 14808002 11 number of I129 atoms and to a value of 2.5 barns 14808002 12 (10**-24 cm2) for the cross section. 14808002 13 ASSUMED (ASSUM,92-U-0(N,F)MASS,CHN,FY) 14808002 14 STATUS (TABLE,,S.Katcoff,J,PR,71,826,1947) 14808002 15 page 826 of J,PR,71,826,1947. 14808002 16 (COREL,14808003) 14808002 17 ENDBIB 15 0 14808002 18 COMMON 1 3 14808002 19 ASSUM 14808002 20 PC/FIS 14808002 21 0.7 14808002 22 ENDCOMMON 3 0 14808002 23 DATA 1 1 14808002 24 DATA 14808002 25 B 14808002 26 2.5 14808002 27 ENDDATA 3 0 14808002 28 ENDSUBENT 27 0 1480800299999 SUBENT 14808003 20230317 150614808003 1 BIB 4 13 14808003 2 REACTION (53-I-129(N,ABS),,SIG,,MXW) 14808003 3 ANALYSIS The other method of estimation is based on an 14808003 4 approximate measurement of the 8.0-day I131 activity 14808003 5 which was present at the end of the 123-day 14808003 6 irradiation in the iodine sample. This assumes that 14808003 7 the bombardment of the uranium was steady, especially 14808003 8 near the end. The fission yield of I131 was taken as 14808003 9 2.5%. This leads to a value of 1.9*10**15 I129 atoms 14808003 10 and to a value of 10 barns for the cross section. 14808003 11 ASSUMED (ASSUM,92-U-0(N,F)53-I-131,CUM,FY) 14808003 12 STATUS (TABLE,,S.Katcoff,J,PR,71,826,1947) 14808003 13 page 826 of J,PR,71,826,1947. 14808003 14 (COREL,14808002) 14808003 15 ENDBIB 13 0 14808003 16 COMMON 1 3 14808003 17 ASSUM 14808003 18 PC/FIS 14808003 19 2.5 14808003 20 ENDCOMMON 3 0 14808003 21 DATA 1 1 14808003 22 DATA 14808003 23 B 14808003 24 10.0 14808003 25 ENDDATA 3 0 14808003 26 ENDSUBENT 25 0 1480800399999 ENDENTRY 3 0 1480899999999