ENTRY 14526 20190329 144914526 0 1 SUBENT 14526001 20190329 144914526 1 1 BIB 6 7 14526 1 2 TITLE The Thermal-Neutron Fission Cross Section of Pu240 14526 1 3 AUTHOR (C.B.Bigham) 14526 1 4 REFERENCE (J,CJP,36,503,1958) 14526 1 5 #doi:10.1139/p58-051 14526 1 6 INSTITUTE (1CANCRC) 14526 1 7 FACILITY (REAC,1CANCRC) The NRX nuclear reactor at Chalk River. 14526 1 8 HISTORY (20190329C) BP 14526 1 9 ENDBIB 7 0 14526 1 10 COMMON 1 3 14526 1 11 EN-DUMMY 14526 1 12 EV 14526 1 13 0.0253 14526 1 14 ENDCOMMON 3 0 14526 1 15 ENDSUBENT 14 0 14526 199999 SUBENT 14526002 20190329 144914526 2 1 BIB 6 35 14526 2 2 REACTION ((94-PU-240(N,F),,SIG,,SPA)/(94-PU-239(N,F),,SIG,,SPA))14526 2 3 SAMPLE Plutonium samples 2 in. in diameter were cut from 14526 2 4 large 0.016 in. aluminum sheets that had been 14526 2 5 uniformly coated with several layers of lacquer 14526 2 6 (cellulose nitrate dissolved in amyl acetate) 14526 2 7 containing plutonium nitrate dissolved in acetone. 14526 2 8 240Pu sample: 14526 2 9 (94-PU-240,ENR=0.89365) 14526 2 10 (94-PU-239,ENR=0.10131) 14526 2 11 (94-PU-241,ENR=0.00483) 14526 2 12 (94-PU-242,ENR=0.00018) 14526 2 13 239Pu sample: 14526 2 14 (94-PU-239,ENR=0.97884) 14526 2 15 (94-PU-240,ENR=0.02043) 14526 2 16 (94-PU-241,ENR=0.00073) 14526 2 17 DETECTOR (FISCH) The samples were mounted on either side of a 14526 2 18 thin aluminum partition in the common cathode of a 14526 2 19 back-to-back gridded ion chamber. For the fission 14526 2 20 counting the chamber was operated at low pressure to 14526 2 21 permit complete discrimination between fission and 14526 2 22 alpha pulses. 14526 2 23 METHOD (RVAL,CHSEP) If isotopically pure samples of Pu239 14526 2 24 and Pu240 are available, the ratio of the 14526 2 25 alpha-disintegration rates and the published ratio of 14526 2 26 the alpha-decay half-lives would give the ratio of 14526 2 27 the masses of the samples. The ratio of the fission 14526 2 28 rates in these samples, when irradiated in the same 14526 2 29 neutron flux, would then give the ratio of the 14526 2 30 fission cross sections. The accuracy would be limited 14526 2 31 to the accuracy with which the ratio of the 14526 2 32 alpha-decay half-lives is known. 14526 2 33 ERR-ANALYS (DATA-ERR) Statistical errors arising from the ratio 14526 2 34 measurements, decay constant ratio errors, 14526 2 35 mass-spectrometer analyses. 14526 2 36 STATUS (TABLE) page 506. 14526 2 37 ENDBIB 35 0 14526 2 38 NOCOMMON 0 0 14526 2 39 DATA 2 1 14526 2 40 DATA DATA-ERR 14526 2 41 NO-DIM NO-DIM 14526 2 42 -9.3E-04 7.7E-04 14526 2 43 ENDDATA 3 0 14526 2 44 ENDSUBENT 43 0 14526 299999 SUBENT 14526003 20190329 144914526 3 1 BIB 5 6 14526 3 2 REACTION (94-PU-240(N,F),,SIG,,SPA) 14526 3 3 MONITOR (94-PU-239(N,F),,SIG,,SPA) 14526 3 4 MONIT-REF ((MONIT),D.J.Hughes+,P,BNL-325,1955) 14526 3 5 ERR-ANALYS (DATA-ERR) No details on sources of uncertainties. 14526 3 6 STATUS (DEP,14526002) 14526 3 7 (TABLE) page 506. 14526 3 8 ENDBIB 6 0 14526 3 9 COMMON 2 3 14526 3 10 MONIT MONIT-ERR 14526 3 11 B B 14526 3 12 900.0 40.0 14526 3 13 ENDCOMMON 3 0 14526 3 14 DATA 2 1 14526 3 15 DATA DATA-ERR 14526 3 16 B B 14526 3 17 -0.8 0.7 14526 3 18 ENDDATA 3 0 14526 3 19 ENDSUBENT 18 0 14526 399999 ENDENTRY 3 0 1452699999999