ENTRY 14400 20140917 14031440000000001 SUBENT 14400001 20140917 14031440000100001 BIB 13 38 1440000100002 TITLE A Study of the Spectrum of the Neutrons of Low Energy 1440000100003 from the Fission of 235U 1440000100004 AUTHOR (T.W.Bonner,R.A.Ferrell,M.C.Rinehart) 1440000100005 REFERENCE (J,PR,87,(6),1032,1952) 1440000100006 #doi:10.1103/PhysRev.87.1032 1440000100007 REL-REF (A,,H.T.Richards,P,LA-(556),1946) 1440000100008 INSTITUTE (1USALAS) 1440000100009 FACILITY (REAC,1USALAS) Los Alamos fast reactor. 1440000100010 INC-SOURCE (REAC) The beam of thermal neutrons had a flux of 1440000100011 5x10**5 neutrons/cm2/sec at a distance of 6 ft from 1440000100012 the face of the reactor pile, where the 235U foil was 1440000100013 placed. 1440000100014 DETECTOR The cloud chamber. 1440000100015 SAMPLE The 235U foil was 3 cm by 10 cm by 0.010 inches thick, 1440000100016 making the source strength of fission neutrons of 1440000100017 3.7x10**7 neutrons/sec. 1440000100018 METHOD (REC) In order to get longer proton tracks for a 1440000100019 given energy in the cloud chamber, hydrogen gas was 1440000100020 used at a pressure of 1/3 of an atmosphere; and water 1440000100021 vapor was used in place of alcohol, reducing the 1440000100022 stopping power of vapor by a factor of about three. 1440000100023 The cloud chamber was placed well outside the beam of 1440000100024 neutrons, at a distance of 35 cm from the 235U 1440000100025 sample. Under the experimental conditions outlined 1440000100026 above, from 5 to 15 recoil protons were obtained each 1440000100027 time the cloud chamber expanded. 2800 pairs of 1440000100028 stereoscopic pictures were taken with the apparatus 1440000100029 and approximately 25000 recoil protons were observed. 1440000100030 ANALYSIS To convert from the number of proton recoils to the 1440000100031 number of primary neutrons one must take into account 1440000100032 the varying cross sections for neutron-proton 1440000100033 scattering. As a final correction one must multiply 1440000100034 by the geometrical correction factor for the 1440000100035 probability of measuring tracks of different lengths 1440000100036 to deduce the relative number of neutrons with 1440000100037 different energies. 1440000100038 ERR-ANALYS (DATA-ERR) No details are given. 1440000100039 HISTORY (20140917C) BP 1440000100040 ENDBIB 38 0 1440000100041 COMMON 1 3 1440000100042 EN 1440000100043 EV 1440000100044 0.0253 1440000100045 ENDCOMMON 3 0 1440000100046 ENDSUBENT 45 0 1440000199999 SUBENT 14400002 20140917 14031440000200001 BIB 3 4 1440000200002 REACTION (92-U-235(N,F),,NU/DE,,REL) 1440000200003 Relative no. of neutrons per 100-keV interval 1440000200004 ASSUMED (ASSUM,1-H-1(N,EL)1-H-1,,SIG) 1440000200005 STATUS (TABLE) Table I, page 1033. 1440000200006 ENDBIB 4 0 1440000200007 NOCOMMON 0 0 1440000200008 DATA 5 6 1440000200009 E-MIN E-MAX DATA DATA-ERR ASSUM 1440000200010 KEV KEV ARB-UNITS ARB-UNITS B 1440000200011 50.0 99.0 34.2 5.0 14.5 1440000200012 100.0 199.0 40.3 4.1 11.6 1440000200013 200.0 299.0 50.6 5.3 9.3 1440000200014 300.0 399.0 55.3 6.5 7.6 1440000200015 400.0 499.0 58.6 7.2 6.6 1440000200016 500.0 699.0 68.0 6.5 5.6 1440000200017 ENDDATA 8 0 1440000200018 ENDSUBENT 17 0 1440000299999 ENDENTRY 2 0 1440099999999