ENTRY 31403 20100220 31443140300000001 SUBENT 31403001 20100220 31443140300100001 BIB 13 44 3140300100002 TITLE Measurement of the prompt neutron spectrum of U-238 3140300100003 fission. 3140300100004 AUTHOR (Li Anli,Bai Xixiang,Wang Xiaozhong,Meng Jiangchen, 3140300100005 Liu Weiping,Yuan Yuan,Huang Shengnian,Chih Tahai) 3140300100006 INSTITUTE (3CPRAEP) 3140300100007 REFERENCE (C,91BEIJIN,,68,199109) 3140300100008 FACILITY (VDGT,3CPRAEP) HI-13 Tandem Van der Graaff accelerator.3140300100009 INC-SOURCE (D-D) Neutrons were produced by bombarding a deuterium 3140300100010 gas cell ( 4.3 atm.) with a 7.4 MeV pulsed deuteron 3140300100011 beam. 3140300100012 SAMPLE Natural uranium electro-deposited on both sides of 3140300100013 0.2 mm thick plates of stainless steel with deposition 3140300100014 thickness of about 0.5 mg/cm**2. 3140300100015 DETECTOR (IOCH,SCIN) Fission fragments were detected by a 3140300100016 parallel-plate ionization chamber which operated in 3140300100017 multi-segment mode and was filled with pure methane at 3140300100018 a pressure of 4.3 atm. Fission neutrons were detected 3140300100019 by two shielded liquid scintillators of 25 cm in diam. 3140300100020 5 cm thick. Both placed at 100 degrees with respect 3140300100021 to the incident neutron beam and at 2.3 m from the 3140300100022 ionization chamber. 3140300100023 METHOD (TOF,COINC,PSD) The incident-neutron TOF spectrum was 3140300100024 obtained from the fission-fragment event signals with 3140300100025 the pulsed-beam TOF method. A liquid scintillator, 3140300100026 located at 0 deg and 3.1 m down stream of the gas cell 3140300100027 served as monitor of the incident-neutron tof spectrum.3140300100028 Fission neutrons were selected by requiring coincidence3140300100029 between neutron detector- and fission-fragment detec- 3140300100030 tor events, which also provided the fission-neutron TOF3140300100031 spectra. Events induced by 10 MeV incident neutrons 3140300100032 were software selected by gating the TOF spectrum of 3140300100033 secundary neutrons with the 10 MeV peak of the incident3140300100034 neutron spectrum. Pulse-shape discrimination was 3140300100035 applied to eliminate gamma-ray background. 3140300100036 ANALYSIS The measured spectrum was fitted by a Maxwellian 3140300100037 distribution. 3140300100038 ERR-ANALYS (DATA-ERR) The error refers to the uncertainties due to3140300100039 * counting statistics and 3140300100040 * determination of detector efficiency. 3140300100041 HISTORY (19921015C) HW 3140300100042 (20090730A) SD:Updated to new date formats,lower case. 3140300100043 STATUS (TABLE) Data are taken from Beijing Intern. Symposium 3140300100044 on Fast Neutron Physics, Beijing, 9 - 13 Sept. 1991, 3140300100045 p. 71. 3140300100046 ENDBIB 44 0 3140300100047 COMMON 1 3 3140300100048 EN 3140300100049 MEV 3140300100050 10. 3140300100051 ENDCOMMON 3 0 3140300100052 ENDSUBENT 51 0 3140300199999 SUBENT 31403002 20100220 31443140300200001 BIB 1 1 3140300200002 REACTION (92-U-238(N,F)0-NN-1,PR,KE) 3140300200003 ENDBIB 1 0 3140300200004 NOCOMMON 0 0 3140300200005 DATA 2 1 3140300200006 DATA DATA-ERR 3140300200007 MEV MEV 3140300200008 2.07 0.06 3140300200009 ENDDATA 3 0 3140300200010 ENDSUBENT 9 0 3140300299999 ENDENTRY 2 0 3140399999999