ENTRY 14295 20170802 14301429500000001 SUBENT 14295001 20170802 14301429500100001 BIB 10 43 1429500100002 TITLE The Multiplicity of Neutron Production by Spontaneous 1429500100003 Fission of Uranium 1429500100004 AUTHOR (K.W.Geiger,D.C.Rose) 1429500100005 REFERENCE (J,CJP,32,498,1954) 1429500100006 #doi:10.1139/p54-052 1429500100007 INSTITUTE (1CANOTC) 1429500100008 DETECTOR (BF3) Two B10F3 neutron counters. The counters were 1429500100009 6.4 cm in diameter and the active length was about 50 1429500100010 cm. 1429500100011 SAMPLE Metallic uranium: Freshly refined natural uranium 1429500100012 metal was used in the form of seven flat strips 40 1429500100013 cm long, 3.4 cm wide, and 0.45 cm thick. 1429500100014 METHOD (ABSFY) The uranium was surrounded by paraffin wax, 1429500100015 and in holes in the wax two B10F3 neutron counters 1429500100016 were placed as shown, centered about 9 cm. below the 1429500100017 uranium. This pile was built on a steel frame, the 1429500100018 paraffin being contained in light steel tanks so that 1429500100019 the whole was demountable. A lead absorber could be 1429500100020 placed on top of the pile up to 25 cm in thickness. 1429500100021 The neutrons which come from one fission event are 1429500100022 slowed down in the paraffin and with a mean life of 1429500100023 about 150 microsec will be captured in the paraffin 1429500100024 or in the boron of the counters. Neutrons recorded in 1429500100025 a suitable time interval after the nuclear event will 1429500100026 therefore have a common origin. But because of the 1429500100027 low efficiency of such an arrangement, only a few of 1429500100028 the released neutrons will be recorded. The amount of 1429500100029 uranium (8.05 kg) used was much too small to produce 1429500100030 a substantial number of thermal-neutron-induced 1429500100031 fissions in U235 by spontaneous fission neutrons 1429500100032 slowed down in the paraffin. This was checked by 1429500100033 surrounding the uranium with cadmium which lowered 1429500100034 the counting efficiency without producing a 1429500100035 significant effect on the final results. The 1429500100036 measurements are considered to apply to U238 since the 1429500100037 amount of U235 and other isotopes is known to be less 1429500100038 than 1% and their spontaneous fission rate is too 1429500100039 small to contribute appreciably. 1429500100040 ERR-ANALYS (DATA-ERR) No details on sources of uncertainties. 1429500100041 CORRECTION Corrections were also necessary for accidental counts 1429500100042 and for dead times of the circuits wherever they 1429500100043 applied. 1429500100044 HISTORY (20170802C) BP 1429500100045 ENDBIB 43 0 1429500100046 NOCOMMON 0 0 1429500100047 ENDSUBENT 46 0 1429500199999 SUBENT 14295002 20170802 14301429500200001 BIB 2 2 1429500200002 REACTION (92-U-238(0,F),,NU) 1429500200003 STATUS (TABLE) Can.J.Phys.32,498, p.507. 1429500200004 ENDBIB 2 0 1429500200005 NOCOMMON 0 0 1429500200006 DATA 2 1 1429500200007 DATA DATA-ERR 1429500200008 PRT/FIS PRT/FIS 1429500200009 2.3 0.2 1429500200010 ENDDATA 3 0 1429500200011 ENDSUBENT 10 0 1429500299999 ENDENTRY 2 0 1429599999999