ENTRY 12851 19980225 00001285100000001 SUBENT 12851001 19980225 00001285100100001 BIB 10 27 1285100100002 INSTITUTE (1USALRL) 1285100100003 REFERENCE (J,NP/A,407,193,8310) 1285100100004 AUTHOR (R.E.HOWE,R.M.WHITE,J.C.BROWN,J.H.LANDRUM,R.J.DOUGAN, 1285100100005 R.W.LOUGHEED,R.J.DUPZYK) 1285100100006 TITLE Measurement of the prompt fission neutron multiplicity 1285100100007 from the 245Cm(n,f) and 242(m)Am(n,f) reactions 1285100100008 SAMPLE 235U vapor was deposited on five tantalum foils, each 1285100100009 6 micro-m thick with 500 microgram/cm2. 1285100100010 Monitor sample 8.3+-0.16 milligrams 235U, 99.8% pure. 1285100100011 DETECTOR (SCIN) NE213 liquid scintillator 12.5 and 5cm long 1285100100012 (FISCH) 1285100100013 Efficiencies for detecting fission events in the 1285100100014 fission chamber was about 95%. 1285100100015 ANALYSIS Pre-fission evaporation spectrum was assumed to be 1285100100016 isotropic for the samples. 1285100100017 ERR-ANALYS (ERR-S) Quoted errors are strictly statistical in 1285100100018 and include the following uncertainties: 1285100100019 1) coincident neutron counts, 1285100100020 2) total fission counts, 1285100100021 3) measured deadtimes, 1285100100022 4) measured backgrounds. 1285100100023 Systematic uncertaity does not exceeded 1/5 of 1285100100024 statistical uncertainty. 1285100100025 STATUS (APRVD) R.E.Howe, 83/1/6. 1285100100026 Data taken from tables in article. 1285100100027 HISTORY (831206C) 1285100100028 (980225A) BIB updates, converted to lower case. 1285100100029 ENDBIB 27 0 1285100100030 NOCOMMON 0 0 1285100100031 ENDSUBENT 30 0 1285100199999 SUBENT 12851002 19980225 00001285100200001 BIB 7 19 1285100200002 REACTION ((96-CM-245(N,F),PR,NU)/(92-U-235(N,F),PR,NU)) 1285100200003 FACILITY (LINAC) Electron Linac. 1285100200004 INC-SOURCE (PHOTO) 'White' neutron beam. 1285100200005 Typical energy uncertainty is +-40 keV at 4 MeV and 1285100200006 +-260 keV at 14 MeV. 1285100200007 SAMPLE Fission chamber was constructed with two samples of 1285100200008 245Cm: 195.3+-4.0 micrograms - 99.9% pure, and 1285100200009 201.0+-4.0 micrograms - 99.2% pure. 1285100200010 METHOD (TOF) Time-of-flight. 13.4-m flight path. 1285100200011 DETECTOR Timing resolution on the fission signals was 1 ns. 1285100200012 The neutron detector threshold was set above 0.3 MeV. 1285100200013 CORRECTION The following corrections were made 1285100200014 (1) Background neutrons in neutron detector (<5%), 1285100200015 (2) Pileup-induced deadtime in neutron detector (<15),1285100200016 (3) Spontaneous-fissioning sample contaminants 1285100200017 (<3% for 99.9% sample, <10% for 99.2% sample) 1285100200018 (4) Geomettrically-induced differences in the neutron 1285100200019 detection efficiency (<1%) 1285100200020 Data were multiplied by a factor of 1.045. 1285100200021 ENDBIB 19 0 1285100200022 NOCOMMON 0 0 1285100200023 DATA 4 16 1285100200024 EN EN-RSL DATA ERR-S 1285100200025 MEV MEV NO-DIM NO-DIM 1285100200026 0.245 0.083 1.516 0.056 1285100200027 0.422 0.099 1.484 0.048 1285100200028 0.63 0.12 1.472 0.046 1285100200029 0.95 0.22 1.485 0.040 1285100200030 1.37 0.22 1.507 0.047 1285100200031 1.93 0.37 1.460 0.048 1285100200032 2.61 0.39 1.458 0.073 1285100200033 3.14 0.24 1.49 0.13 1285100200034 3.81 0.56 1.40 0.13 1285100200035 4.81 0.62 1.31 0.10 1285100200036 5.78 0.60 1.34 0.12 1285100200037 6.82 0.77 1.17 0.10 1285100200038 7.75 0.58 1.22 0.14 1285100200039 9.0 1.2 1.18 0.10 1285100200040 11.1 1.6 1.22 0.13 1285100200041 14.1 2.2 1.13 0.16 1285100200042 ENDDATA 18 0 1285100200043 ENDSUBENT 42 0 1285100299999 SUBENT 12851003 19980225 00001285100300001 BIB 6 21 1285100300002 REACTION ((96-CM-245(N,F),PR,NU)/(92-U-235(N,F),PR,NU)) 1285100300003 FACILITY (ICTR) 1285100300004 INC-SOURCE (D-T) 1285100300005 Neutrons collimated by series of iron, polyethylene 1285100300006 and boron-loaded polyethylene collimators. 1285100300007 SAMPLE Fission chamber was constructed with two samples of 1285100300008 245Cm: 195.3+-4.0 micrograms - 99.9% pure, and 1285100300009 201.0+-4.0 micrograms - 99.2% pure. 1285100300010 METHOD (TOF) Time-of-flight. 3-m flight path. 1285100300011 CORRECTION The following corrections were made 1285100300012 1) Background fission events (26.1% in the peak 1285100300013 region of TOF spectrum, 1285100300014 2) 6.3% correction was applied to compensate for 1285100300015 routing-circuit-induced differences in gain 1285100300016 between the fission spectrum and the coincident 1285100300017 spectrum, 1285100300018 3) Corrections for scintillator efficiency for 1285100300019 detection of fission neutrons are- 1285100300020 a) <=1.3+-0.8% for sample location differences. 1285100300021 b) <=1.7+-1.5% for differences in fission neutron 1285100300022 spectrum distributions. 1285100300023 ENDBIB 21 0 1285100300024 NOCOMMON 0 0 1285100300025 DATA 3 1 1285100300026 EN DATA ERR-S 1285100300027 MEV NO-DIM NO-DIM 1285100300028 14.1 1.035 0.69 1285100300029 ENDDATA 3 0 1285100300030 ENDSUBENT 29 0 1285100399999 SUBENT 12851004 19980225 00001285100400001 BIB 6 20 1285100400002 REACTION ((95-AM-242-M(N,F),PR,NU)/(92-U-235(N,F),PR,NU)) 1285100400003 FACILITY (ICTR) 1285100400004 INC-SOURCE (D-T) 1285100400005 Neutrons collimated by series of iron, polyethylene 1285100400006 and boron-loaded polyethylene collimators. 1285100400007 SAMPLE Fission chamber constructed with 207.3+-2.0 microgram 1285100400008 sample of 242AM, 99.2% pure. 1285100400009 METHOD (TOF) Time-of-flight. 3-m flight path. 1285100400010 CORRECTION The following corrections were made 1285100400011 1) Background fission events (26.1% in the peak 1285100400012 region of TOF spectrum, 1285100400013 2) 6.3% correction was applied to compensate for 1285100400014 routing-circuit-induced differences in gain 1285100400015 between the fission spectrum and the coincident 1285100400016 spectrum, 1285100400017 3) Corrections for scintillator efficiency for 1285100400018 detection of fission neutrons are- 1285100400019 a) <=1.3+-0.8% for sample location differences. 1285100400020 b) <=1.7+-1.5% for differences in fission neutron 1285100400021 spectrum distributions. 1285100400022 ENDBIB 20 0 1285100400023 NOCOMMON 0 0 1285100400024 DATA 3 1 1285100400025 EN DATA ERR-S 1285100400026 MEV NO-DIM NO-DIM 1285100400027 14.1 1.25 0.14 1285100400028 ENDDATA 3 0 1285100400029 ENDSUBENT 28 0 1285100499999 SUBENT 12851005 19980225 00001285100500001 BIB 8 21 1285100500002 REACTION ((96-CM-245(N,F),PR,NU)/(92-U-235(N,F),PR,NU)) 1285100500003 FACILITY (LINAC) Electron Linac. 1285100500004 INC-SOURCE (PHOTO) 'White' neutron beam. 1285100500005 INC-SPECT Centroid energy 0.05 eV. 1285100500006 SAMPLE Fission chamber was constructed with two samples of 1285100500007 245Cm: 195.3+-4.0 micrograms - 99.9% pure, and 1285100500008 201.0+-4.0 micrograms - 99.2% pure. 1285100500009 METHOD (TOF) Time-of-flight. 13.4-m flight path. 1285100500010 DETECTOR Timing resolution on the fission signals was 1 ns. 1285100500011 The neutron detector threshold was set above 0.3 MeV. 1285100500012 CORRECTION The following corrections were made 1285100500013 (1) Background neutrons in neutron detector (<5%), 1285100500014 (2) Pileup-induced deadtime in neutron detector (<15),1285100500015 (3) Spontaneous-fissioning sample contaminants 1285100500016 (<3% for 99.9% sample, <10% for 99.2% sample) 1285100500017 (4) Geomettrically-induced differences in the neutron 1285100500018 detection efficiency (<1%) 1285100500019 Due to large thermal flux and minimal background 1285100500020 events and detector dead times the corrections to 1285100500021 the 0.05 eV raw data were much smaller than those 1285100500022 listed above which are required for high energy data. 1285100500023 ENDBIB 21 0 1285100500024 NOCOMMON 0 0 1285100500025 DATA 4 1 1285100500026 EN-MIN EN-MAX DATA ERR-S 1285100500027 EV EV NO-DIM NO-DIM 1285100500028 0.019 0.7 1.508 0.025 1285100500029 ENDDATA 3 0 1285100500030 ENDSUBENT 29 0 1285100599999 ENDENTRY 5 0 1285199999999