ENTRY 14665 20201207 14761466500000001 SUBENT 14665001 20201207 14761466500100001 BIB 11 33 1466500100002 TITLE Fission Cross-Section of U235 for Intermediate 1466500100003 Velocity Neutrons 1466500100004 AUTHOR (O.Chamberlain,J.W.Kennedy,E.Segre) 1466500100005 REFERENCE (R,CF-403,1942) 1466500100006 REL-REF (O,L0264001,O.Chamberlain+,R,CF-403,1942) Photo 1466500100007 disintegration data. 1466500100008 (I,,G.T.Seaborg+,J,PR,55,808,1939) Ionization chamber 1466500100009 description. 1466500100010 INSTITUTE (1USABRK) 1466500100011 FACILITY (CYCLO,1USABRK) Production of photoneutron sources. 1466500100012 DETECTOR (IOCH,GEMUC) Ionization chamber was filled with freon. 1466500100013 SAMPLE The uranium samples were deposited as ammonium nitrate 1466500100014 or as U3O8 on platinum discs; discs of 5 or 3.3 cm 1466500100015 diameter and their distance from the bottom of the 1466500100016 neutron sources varied between 3.40 cm and 1.86 cm in 1466500100017 the various runs. 1466500100018 METHOD (MANGB) For monokinetic energies photoneutron sources 1466500100019 were selected; they were produced by power 1466500100020 artificial gamma sources generated by Berkeley 1466500100021 cyclotron. The total number of photoneutrons was 1466500100022 determined by slowing them in a large bath of 1466500100023 manganous sulphite, and a fraction of neutrons 1466500100024 crossing the uranium sample was calculated. The 1466500100025 neutron source was put immediately above an 1466500100026 ionization chamber connected to a linear amplifier 1466500100027 and containing the uranium samples to be investigated. 1466500100028 ANALYSIS From the observed count (R) the fission cross section 1466500100029 was obtained using the formula: R = sigma x Phi x S, 1466500100030 where sigma is the cross section in square cm, Phi is 1466500100031 the number of neutron crossing the perpendicular to 1466500100032 the sample per unit of time, and S is the number of 1466500100033 uranium nuclei per square cm. 1466500100034 HISTORY (20201207C) BP 1466500100035 ENDBIB 33 0 1466500100036 NOCOMMON 0 0 1466500100037 ENDSUBENT 36 0 1466500199999 SUBENT 14665002 20201207 14761466500200001 BIB 3 5 1466500200002 REACTION (92-U-235(N,F),,SIG) 1466500200003 INC-SOURCE (PHOTO) 220 keV neutrons were produced Y(photons) +Be. 1466500200004 The yttrium gamma sources were contained in small 1466500200005 glass seeds (approximately 0.5 cm in diameter) . 1466500200006 STATUS (TABLE) page 1. 1466500200007 ENDBIB 5 0 1466500200008 NOCOMMON 0 0 1466500200009 DATA 2 1 1466500200010 EN DATA 1466500200011 KEV B 1466500200012 220.0 2.8 1466500200013 ENDDATA 3 0 1466500200014 ENDSUBENT 13 0 1466500299999 SUBENT 14665003 20201207 14761466500300001 BIB 3 5 1466500300002 REACTION (92-U-235(N,F),,SIG) 1466500300003 INC-SOURCE (PHOTO) 430 keV neutrons were produced 24Na(photons) 1466500300004 +D. The radioactive sodium was dissolved in D2O 99% 1466500300005 pure, contained in a glass sphere. 1466500300006 STATUS (TABLE) page 1. 1466500300007 ENDBIB 5 0 1466500300008 NOCOMMON 0 0 1466500300009 DATA 2 1 1466500300010 EN DATA 1466500300011 KEV B 1466500300012 430.0 1.7 1466500300013 ENDDATA 3 0 1466500300014 ENDSUBENT 13 0 1466500399999 ENDENTRY 3 0 1466599999999