ENTRY 22153 19910103 00002215300000001 SUBENT 22153001 19910103 00002215300100001 BIB 13 63 2215300100002 REFERENCE (J,NIM/A,287,570,90) 2215300100003 TITLE -APPLICATION OF A RESONANCE CAPTURE DETECTOR TO THE 2215300100004 PRECISE MEASUREMENT OF NEUTRON TOTAL CROSS SECTIONS. 2215300100005 AUTHOR (K.KOBAYASHI,S.YAMAMOTO,Y.FUJITA) 2215300100006 INSTITUTE (2JPNKTO) 2215300100007 FACILITY (LINAC,2JPNKTO) THE 46 MEV ELECTRON LINAC AT THE 2215300100008 RESEARCH REACTOR INSTITUTE OF KYOTO UNIVERSITY, OPERA-2215300100009 TED AT A FREQUENCY OF 300 PULSES/SEC AND WITH A PULSE 2215300100010 WIDTH OF 68 NS, ELECTRON ENERGY 32 MEV AND PEAK 2215300100011 CURRENT 2 A. 2215300100012 INC-SOURCE (PHOTO) BURSTS OF NEUTRONS WERE PRODUCED FROM THE 2215300100013 WATER-COOLED PHOTONEUTRON TARGET, WHICH WERE MADE OF 2215300100014 SEVERAL SHEETS OF TA PLATES, 5 CM BY 5 CM SQUARE WITH 2215300100015 AN EFFECTIVE TOTAL THICKNESS OF ABOUT 3.5 CM. THE TAR-2215300100016 GET WAS PLACED IN THE CENTER OF AN OCTAGONAL WATER 2215300100017 TANK, 30 CM IN DIAMETER AND 10 CM THICK, TO MODERATE 2215300100018 THE NEUTRONS. A 7 CM DIAMETER BY 20 CM LONG PB BLOCK 2215300100019 WAS PLACED IN THE FLIGHT PATH IN FRONT OF THE TARGET 2215300100020 TO SUPPRESS THE PROMPT GAMMA-FLASH. THE NEUTRON BEAM 2215300100021 WAS AT AN ANGLE OF 135 DEG TO THE LINAC BEAM AND WAS 2215300100022 REDUCED TO 2 CM DIAMETER AT THE DETECTOR POSITION 2215300100023 USING B4C, LI2CO3 AND PB COLLIMATORS. A 0.5 MM THICK 2215300100024 CD FILTER WAS PLACED IN THE NEUTRON BEAM TO SUPPRESS 2215300100025 OVERLAP OF THERMAL NEUTRONS FROM PREVIOUS PULSES. 2215300100026 METHOD (TOF ) TIME-OF-FLIGHT TRANSMISSION MEASUREMENT WITH A 2215300100027 FLIGHT PATH 12.7 M. 2215300100028 DETECTOR (SCIN ) A RESONANCE CAPTURE DETECTOR CONSISTING OF 8 2215300100029 PIECES OF BI4-GE3-O12 (BGO) CRYSTAL SCINTILLATOR AND 2215300100030 A CAPTURE SAMPLE OF TA. THE CRYSTALS, 5 X 5 CM SQUARE 2215300100031 AND 7.5 CM THICK, WERE ASSEMBLED INTO A BANK LEAVING A2215300100032 THROUGH HOLE 2.7 X 2.7 CM SQUARE, THE INSIDE OF WHICH 2215300100033 WAS COATED WITH 3 MM THICK ENRICHED 6-LIF TILES. THE 2215300100034 TA CAPTURE SAMPLE WAS A 1.8 X 1.8 CM SQUARE PLATE, 2215300100035 1 MM THICK, PLACED AT THE CENTRE OF THE BGO HOLE. THE 2215300100036 BGO CRYSTALS ARE A TOTAL ABSORPTION DETECTOR IN THE 2215300100037 MEASUREMENT OF CAPTURE GAMMAS, AND THUS THE RESONANCE 2215300100038 DETECTOR IS SENSITIVE ESPECIALLY TO NEUTRONS AT THE 2215300100039 RESONANCE ENERGIES OF THE TA(N,G) REACTION. THE BACK- 2215300100040 GROUND LEVEL WAS DETERMINED USING A TA SAMPLE ALSO IN 2215300100041 THE TOF BEAM, A SO-CALLED SELF-INDICATION MEASUREMENT,2215300100042 AND VERIFIED WITH NOTCH FILTERS SUCH AS AG AND CO. 2215300100043 .DETECTOR PERFORMACE WAS CHECKED BY MAKING NEUTRON 2215300100044 TRANSMISSION MEASUREMENTS WITH POLYETHYLENE, THE 2215300100045 RESULTS SHOWING VERY GOOD AGREEMENT WITH ENDF/B-IV. 2215300100046 .THIS RESONANCE CAPTURE DETECTOR HAS ALSO BEEN USED TO 2215300100047 MEASURE THE TOTAL SB CROSS SECTION, SEE EXFOR 2215300100048 22154.004. 2215300100049 (PROPC) A BF3 PROPORTIONAL COUNTER MONITORED NEUTRON 2215300100050 INTENSITY DURING THE EXPERIMENT. 2215300100051 SAMPLE .THREE TRANSMISSION SAMPLES IN THE FORM OF METALLIC PB 2215300100052 PLATES, EACH 5 X 5 CM SQUARE AND 0.5 CM THICK, PURITY 2215300100053 99.9993%, THE SAMPLE THICKNESSES BEING 0.09858, 2215300100054 0.13152 AND 0.16478 ATOMS/BARN. THE SAMPLES WERE 2215300100055 LOCATED ABOUT 10 M FROM THE TA TARGET. 2215300100056 CORRECTION .THE DATA WERE CORRECTED FOR DEAD-TIME LOSSES AND BACK-2215300100057 GROUND. 2215300100058 ERR-ANALYS (DATA-ERR) THE ERRORS GIVEN CONTAIN BOTH STATISTICAL 2215300100059 AND SYSTEMATIC CONTRIBUTIONS. UNCERTAINTIES ARE DUE 2215300100060 MAINLY TO THE TRANSMISSION RATE STATISTICS AND THE 2215300100061 SAMPLE THICKNESS. 2215300100062 STATUS .DATA TAKEN FROM MAIN REF. 2215300100063 HISTORY (901001C) S.W. 2215300100064 (910103E) 2215300100065 ENDBIB 63 0 2215300100066 NOCOMMON 0 0 2215300100067 ENDSUBENT 66 0 2215300199999 SUBENT 22153002 19910103 00002215300200001 BIB 4 9 2215300200002 REACTION (82-PB-0(N,TOT),,SIG) 2215300200003 COMMENT .THE INCIDENT ENERGIES AND RESOLUTIONS CORRESPOND TO 2215300200004 THE RESONANCE PEAKS AND FWHM OF THE CAPTURE SAMPLE, 2215300200005 TA, USED IN THE BGO RESONANCE CAPTURE DETECTOR. 2215300200006 .NOISE/SIGNAL RATIOS (OPEN BEAM) RANGED FROM 0.0058 AT 2215300200007 4.28 EV TO 0.0080 AT 39.1 EV. 2215300200008 STATUS .DATA TAKEN FROM MAIN REF. 2215300200009 HISTORY (901001C) S.W. 2215300200010 (910103E) 2215300200011 ENDBIB 9 0 2215300200012 NOCOMMON 0 0 2215300200013 DATA 4 6 2215300200014 EN EN-RSL-FW DATA DATA-ERR 2215300200015 EV EV B B 2215300200016 4.28 0.30 11.17 0.025 2215300200017 10.4 0.34 11.18 0.036 2215300200018 14.0 0.26 11.18 0.051 2215300200019 23.9 0.54 11.17 0.040 2215300200020 35.9 1.17 11.18 0.037 2215300200021 39.1 1.11 11.18 0.045 2215300200022 ENDDATA 8 0 2215300200023 ENDSUBENT 22 0 2215300299999 ENDENTRY 2 0 2215399999999