ENTRY 14739 20220126 14961473900000001 SUBENT 14739001 20220126 14961473900100001 BIB 11 41 1473900100002 TITLE Delayed Neutrons from Pu239 1473900100003 AUTHOR (F.De Hoffmann,B.T.Feld) 1473900100004 REFERENCE (J,PR,72,567,1947) Main reference. 1473900100005 #doi:10.1103/PhysRev.72.567 1473900100006 (R,LA-231,1945) 1473900100007 INSTITUTE (1USALAS) 1473900100008 FACILITY (REAC,1USALAS) 1473900100009 INC-SPECT Irradiations were performed in the graphite thermal 1473900100010 column of the Los Alamos "water boiler" (a chain- 1473900100011 reacting assembly operating mainly on thermal neutrons)1473900100012 . The ratio of activities of an indium foil without 1473900100013 and with cadmium covering (cadmium ratio) at the 1473900100014 position of irradiation was of the order of a 1473900100015 thousand or better. Hence the neutron spectrum was 1473900100016 predominately thermal. 1473900100017 SAMPLE Metal samples of both Pu239 and U235 were available 1473900100018 for this experiment. The metal samples were each 1473900100019 covered with cadmium save on one face. The samples 1473900100020 were sufficiently thick so that they could be 1473900100021 considered essentially infinitely thick for thermal 1473900100022 neutrons. 1473900100023 DETECTOR (FISCH) The detector used was a flat parallel plate 1473900100024 U235 fission chamber which was embedded in the 1473900100025 paraffin. The paraffin arrangement served to increase 1473900100026 the counting efficiency for fast neutrons and also 1473900100027 tended to equalize the counting efficiency for 1473900100028 neutrons of different initial energies. 1473900100029 METHOD (INTB) The sample was attached to a string and could 1473900100030 be pulled out of the center of the thermal column 1473900100031 into the paraffin geometry for counting. The length 1473900100032 of time it took for the sample to be pulled from the 1473900100033 thermal column into the paraffin geometry was just 1473900100034 under 2 seconds. Counting was therefore started 2 1473900100035 seconds after the sample began to move (2-second 1473900100036 runs). A second set of data was taken by starting 1473900100037 the counter 5 seconds after the sample began to move 1473900100038 (5-second runs). 1473900100039 ERR-ANALYS (DATA-ERR) Experimental errors: Errors indicated are 1473900100040 conservative guesses based on the largest deviation 1473900100041 observed. 1473900100042 HISTORY (20220126C) BP 1473900100043 ENDBIB 41 0 1473900100044 COMMON 1 3 1473900100045 EN-DUMMY 1473900100046 EV 1473900100047 0.0253 1473900100048 ENDCOMMON 3 0 1473900100049 ENDSUBENT 48 0 1473900199999 SUBENT 14739002 20220126 14961473900200001 BIB 3 8 1473900200002 REACTION (((94-PU-239(N,F),DL,NU,,SPA/MSC)/ 1473900200003 (94-PU-239(N,F),,NU,,SPA))/ 1473900200004 ((92-U-235(N,F),DL,NU,,SPA/MSC)/ 1473900200005 (92-U-235(N,F),,NU,,SPA))) 1473900200006 Relative number of delayed neutrons in Pu239 to that 1473900200007 in U235 as measured after more than 2 seconds 1473900200008 METHOD 2 s runs. 1473900200009 STATUS (TABLE) page 569 of the main reference. 1473900200010 ENDBIB 8 0 1473900200011 NOCOMMON 0 0 1473900200012 DATA 2 1 1473900200013 DATA DATA-ERR 1473900200014 NO-DIM NO-DIM 1473900200015 0.47 0.07 1473900200016 ENDDATA 3 0 1473900200017 ENDSUBENT 16 0 1473900299999 SUBENT 14739003 20220126 14961473900300001 BIB 3 8 1473900300002 REACTION (((94-PU-239(N,F),DL,NU,,SPA/MSC)/ 1473900300003 (94-PU-239(N,F),,NU,,SPA))/ 1473900300004 ((92-U-235(N,F),DL,NU,,SPA/MSC)/ 1473900300005 (92-U-235(N,F),,NU,,SPA))) 1473900300006 Relative number of delayed neutrons in Pu239 to that 1473900300007 in U235 as measured after more than 5 seconds 1473900300008 METHOD 5 s runs. 1473900300009 STATUS (TABLE) page 569 of the main reference. 1473900300010 ENDBIB 8 0 1473900300011 NOCOMMON 0 0 1473900300012 DATA 2 1 1473900300013 DATA DATA-ERR 1473900300014 NO-DIM NO-DIM 1473900300015 0.40 0.06 1473900300016 ENDDATA 3 0 1473900300017 ENDSUBENT 16 0 1473900399999 ENDENTRY 3 0 1473999999999