ENTRY 14670 20201207 14761467000000001 SUBENT 14670001 20201207 14761467000100001 BIB 9 14 1467000100002 TITLE Measurements on sigmaf(49)/sigmaf(25) and the Value 1467000100003 of sigmaf as a Function of Neutron Energy 1467000100004 AUTHOR (R.F.Taschek,J.H.Williams,J.M.Blair,K.Greisen, 1467000100005 A.O.Hanson,R.Perry,C.H.Turner,J.H.Williams) 1467000100006 REFERENCE (R,LA-28,1943) 1467000100007 INSTITUTE (1USALAS) 1467000100008 FACILITY (VDG,1USALAS) 1467000100009 INC-SOURCE (P-LI7) The source of neutrons used in the higher- 1467000100010 energy measurements was a 60 keV thick lithium target 1467000100011 bombarded with controlled-energy protons accelerated 1467000100012 in a Van de Graaff generator. 1467000100013 DETECTOR (IOCH) 1467000100014 DECAY-DATA (94-PU-239,21300.YR) 1467000100015 HISTORY (20201207C) BP 1467000100016 ENDBIB 14 0 1467000100017 NOCOMMON 0 0 1467000100018 ENDSUBENT 17 0 1467000199999 SUBENT 14670002 20201207 14761467000200001 BIB 4 23 1467000200002 REACTION ((94-PU-239(N,F),,SIG)/(92-U-235(N,F),,SIG)) 1467000200003 METHOD (COINC) In order to extend measurements of the 1467000200004 relative cross sections to energies other than 1467000200005 thermal it is necessary to use more massive foils of 1467000200006 239Pu which are not necessarily thin for the emission 1467000200007 of fission fragments. The effective mass of the 239Pu 1467000200008 sample used in these experiments was found to be 17.2 1467000200009 micrograms by measuring the relative fission rates of 1467000200010 this sample and a 17.9 microgram thin foil of 235U 1467000200011 simultaneously irradiated by slow neutrons. These 1467000200012 foils were mounted back to back on opposite sides of 1467000200013 the high voltage electrode of an ionization 1467000200014 comparison chamber containing air at atmospheric 1467000200015 pressure. 1467000200016 ERR-ANALYS (DATA-ERR) The errors shown in the 1467000200017 239Pu(n,f)/235U(n,f) figure are calculated from the 1467000200018 statistics of the new under of fission fragments 1467000200019 counted in each case except for the highest-energy 1467000200020 point. In this case some of the error arises from 1467000200021 uncertainty of the amount of 238U present in the 235U 1467000200022 sample since at this neutron energy approximately 1/3 1467000200023 of the fissions were of the 238U in the sample. 1467000200024 STATUS (CURVE) Fig. 3, page 9. 1467000200025 ENDBIB 23 0 1467000200026 NOCOMMON 0 0 1467000200027 DATA 3 7 1467000200028 EN DATA DATA-ERR 1467000200029 MEV NO-DIM NO-DIM 1467000200030 0.083 1.084 0.058 1467000200031 0.229 1.098 0.055 1467000200032 0.362 1.102 0.080 1467000200033 0.479 1.257 0.114 1467000200034 0.565 1.617 0.044 1467000200035 0.917 1.682 0.090 1467000200036 1.460 1.682 0.091 1467000200037 ENDDATA 9 0 1467000200038 ENDSUBENT 37 0 1467000299999 SUBENT 14670003 20201207 14761467000300001 BIB 5 7 1467000300002 REACTION (94-PU-239(N,F),,SIG) 1467000300003 MONITOR (92-U-235(N,F),,SIG) 1467000300004 MONIT-REF (14666002,A.O.Hanson,R,CF-618,1943) sigma(235U) from 1467000300005 the coincidence proportional counter data. 1467000300006 ERR-ANALYS (DATA-ERR) No details on sources of uncertainties. 1467000300007 STATUS (DEP,14670002) 1467000300008 (CURVE) Fig. 4, page 10. 1467000300009 ENDBIB 7 0 1467000300010 NOCOMMON 0 0 1467000300011 DATA 3 7 1467000300012 EN DATA DATA-ERR 1467000300013 MEV B B 1467000300014 0.087 4.317 0.216 1467000300015 0.229 2.872 0.142 1467000300016 0.359 2.207 0.171 1467000300017 0.478 2.236 0.194 1467000300018 0.565 2.743 0.080 1467000300019 0.948 2.717 0.137 1467000300020 1.458 2.692 0.142 1467000300021 ENDDATA 9 0 1467000300022 ENDSUBENT 21 0 1467000399999 SUBENT 14670004 20201207 14761467000400001 BIB 3 12 1467000400002 REACTION (((94-PU-239(N,F),,SIG)/(92-U-235(N,F),,SIG))// 1467000400003 ((94-PU-239(N,F),,SIG)/(92-U-235(N,F),,SIG))) 1467000400004 METHOD (COINC) Observations of the fission rates with 1467000400005 thermal neutrons were made with and without a Cd 1467000400006 shield covering the chamber. This shield reduced the 1467000400007 fission rate to one per cent of the unshielded value. 1467000400008 In the case of thermal-neutron measurements, the 1467000400009 ionization chamber was situated approximately 3 1467000400010 inches from the target and a block of paraffin 1467000400011 approximately l8 inches on a side surrounded both the 1467000400012 chamber and the target. 1467000400013 STATUS (TABLE) page 5. 1467000400014 ENDBIB 12 0 1467000400015 NOCOMMON 0 0 1467000400016 DATA 3 1 1467000400017 EN-NM EN-DN DATA 1467000400018 MEV EV NO-DIM 1467000400019 1.0 0.0253 0.92 1467000400020 ENDDATA 3 0 1467000400021 ENDSUBENT 20 0 1467000499999 ENDENTRY 4 0 1467099999999