ENTRY 14526 20190329 14491452600000001 SUBENT 14526001 20190329 14491452600100001 BIB 6 7 1452600100002 TITLE The Thermal-Neutron Fission Cross Section of Pu240 1452600100003 AUTHOR (C.B.Bigham) 1452600100004 REFERENCE (J,CJP,36,503,1958) 1452600100005 #doi:10.1139/p58-051 1452600100006 INSTITUTE (1CANCRC) 1452600100007 FACILITY (REAC,1CANCRC) The NRX nuclear reactor at Chalk River. 1452600100008 HISTORY (20190329C) BP 1452600100009 ENDBIB 7 0 1452600100010 COMMON 1 3 1452600100011 EN-DUMMY 1452600100012 EV 1452600100013 0.0253 1452600100014 ENDCOMMON 3 0 1452600100015 ENDSUBENT 14 0 1452600199999 SUBENT 14526002 20190329 14491452600200001 BIB 6 35 1452600200002 REACTION ((94-PU-240(N,F),,SIG,,SPA)/(94-PU-239(N,F),,SIG,,SPA))1452600200003 SAMPLE Plutonium samples 2 in. in diameter were cut from 1452600200004 large 0.016 in. aluminum sheets that had been 1452600200005 uniformly coated with several layers of lacquer 1452600200006 (cellulose nitrate dissolved in amyl acetate) 1452600200007 containing plutonium nitrate dissolved in acetone. 1452600200008 240Pu sample: 1452600200009 (94-PU-240,ENR=0.89365) 1452600200010 (94-PU-239,ENR=0.10131) 1452600200011 (94-PU-241,ENR=0.00483) 1452600200012 (94-PU-242,ENR=0.00018) 1452600200013 239Pu sample: 1452600200014 (94-PU-239,ENR=0.97884) 1452600200015 (94-PU-240,ENR=0.02043) 1452600200016 (94-PU-241,ENR=0.00073) 1452600200017 DETECTOR (FISCH) The samples were mounted on either side of a 1452600200018 thin aluminum partition in the common cathode of a 1452600200019 back-to-back gridded ion chamber. For the fission 1452600200020 counting the chamber was operated at low pressure to 1452600200021 permit complete discrimination between fission and 1452600200022 alpha pulses. 1452600200023 METHOD (RVAL,CHSEP) If isotopically pure samples of Pu239 1452600200024 and Pu240 are available, the ratio of the 1452600200025 alpha-disintegration rates and the published ratio of 1452600200026 the alpha-decay half-lives would give the ratio of 1452600200027 the masses of the samples. The ratio of the fission 1452600200028 rates in these samples, when irradiated in the same 1452600200029 neutron flux, would then give the ratio of the 1452600200030 fission cross sections. The accuracy would be limited 1452600200031 to the accuracy with which the ratio of the 1452600200032 alpha-decay half-lives is known. 1452600200033 ERR-ANALYS (DATA-ERR) Statistical errors arising from the ratio 1452600200034 measurements, decay constant ratio errors, 1452600200035 mass-spectrometer analyses. 1452600200036 STATUS (TABLE) page 506. 1452600200037 ENDBIB 35 0 1452600200038 NOCOMMON 0 0 1452600200039 DATA 2 1 1452600200040 DATA DATA-ERR 1452600200041 NO-DIM NO-DIM 1452600200042 -9.3E-04 7.7E-04 1452600200043 ENDDATA 3 0 1452600200044 ENDSUBENT 43 0 1452600299999 SUBENT 14526003 20190329 14491452600300001 BIB 5 6 1452600300002 REACTION (94-PU-240(N,F),,SIG,,SPA) 1452600300003 MONITOR (94-PU-239(N,F),,SIG,,SPA) 1452600300004 MONIT-REF ((MONIT),D.J.Hughes+,P,BNL-325,1955) 1452600300005 ERR-ANALYS (DATA-ERR) No details on sources of uncertainties. 1452600300006 STATUS (DEP,14526002) 1452600300007 (TABLE) page 506. 1452600300008 ENDBIB 6 0 1452600300009 COMMON 2 3 1452600300010 MONIT MONIT-ERR 1452600300011 B B 1452600300012 900.0 40.0 1452600300013 ENDCOMMON 3 0 1452600300014 DATA 2 1 1452600300015 DATA DATA-ERR 1452600300016 B B 1452600300017 -0.8 0.7 1452600300018 ENDDATA 3 0 1452600300019 ENDSUBENT 18 0 1452600399999 ENDENTRY 3 0 1452699999999