ENTRY 22139 19891211 00002213900000001 SUBENT 22139001 19891211 00002213900100001 BIB 16 51 2213900100002 REFERENCE (J,NSE,102,428,89) 2213900100003 TITLE -CROSS SECTION MEASUREMENT OF THE 3-HE(N,GAMMA) 2213900100004 REACTION AT EN = 24.5 KEV. 2213900100005 AUTHOR (R.WERVELMAN,H.POSTMA,K.ABRAHAMS,F.STECHER-RASMUSSEN, 2213900100006 G.J.DAVIDS,G.J.C.BOTS) 2213900100007 INSTITUTE (2NEDRCN) R.W., K.A., F.S. AND EXPERIMENTAL SITE. 2213900100008 (2NEDDEL) H.P., G.J.D., G.J.C.B. 2213900100009 FACILITY (REAC ) HIGH FLUX REACTOR IN PETTEN. 2213900100010 INC-SOURCE (REAC ) 24.5 KEV NEUTRONS WERE PRODUCED BY FILTERING 2213900100011 THE REACTOR NEUTRONS IN ONE OF THE HORIZONTAL BEAM 2213900100012 TUBES. THE 2.4 CM DIAMETER FILTER CONSISTED OF 22.5 CM2213900100013 IRON, 36 CM ALUMINIUM AND 6.5 CM SULPHUR. THE 24.5 KEV2213900100014 NEUTRON FLUX WAS 3.6 +/- 0.3 TIMES E+5 NEUTRONS/CM2 2213900100015 AND SECOND. 2213900100016 INC-SPECT .QUASIMONOENERGETIC 24.5 KEV NEUTRON BEAM WITH A CON- 2213900100017 TAMINATION OF A FEW PERCENT EPITHERMAL NEUTRONS. 2213900100018 METHOD (EXTB ) THE 3-HE TARGET WAS IRRADIATED BY THE FILTERED 2213900100019 24.5 KEV NEUTRON BEAM. 2213900100020 (ACTIV) ACTIVATION OF GOLD FOILS WERE USED AS NEUTRON 2213900100021 FLUX MONITOR. 2213900100022 DETECTOR (NAICR) THE CAPTURE GAMMA-RAYS WERE MEASURED WITH A 2213900100023 3 X 3 INCH NAI/TL/ DETECTOR, PLACED 9.4 CM FROM THE 2213900100024 TARGET AND PERPENDICULAR TO THE BEAM. THE DETECTOR WAS2213900100025 SHIELDED WITH 10 CM OF LEAD AND WITH HYDROGEN- AND 2213900100026 BORON-CONTAINING MATERIALS. 2213900100027 (SCIN ) ACTIVE SHIELDING AGAINST COSMIC RAYS WAS PRO- 2213900100028 VIDED BY A LARGE DETECTOR, 1000 CM2, WHICH CONSISTED 2213900100029 OF LAYERS OF SCINTILLATING PLASTIC SANDWICHED WITH 5 2213900100030 CM THICK LAYERS OF LEAD. THE RESPONSE OF THE NAI 2213900100031 DETECTOR FOR 20.6 MEV GAMMA-RAYS WAS MEASURED USING 2213900100032 PROTON CAPTURE GAMMA-RAYS AT THE UTRECHT VDG ACCELER- 2213900100033 ATOR. THE EFFICIENCY OF THE DETECTOR WAS CALCULATED 2213900100034 WITH A MONTE CARLO SIMULATION COMPUTER CODE. 2213900100035 PART-DET (G ) 2213900100036 MONITOR (79-AU-197(N,G)79-AU-198,,SIG) A STACK OF NINE 50 2213900100037 MG/CM2 THICK AU FOILS, COVERED ON BOTH SIDES WITH 1 MM2213900100038 THICK CADMIUM SHEETS, WAS USED FOR NEUTRON FLUX DETER-2213900100039 MINATION. BY STUDYING THE ACTIVITIES THROUGH THE 2213900100040 FOILS, CORRECTIONS FOR THE EPITHERMAL NEUTRONS COULD 2213900100041 BE APPLIED. 2213900100042 SAMPLE .TO ABTAIN A SIZABLE 3-HE TARGET DENSITY, AN ALUMINIUM 2213900100043 TARGET GAS CELL, 10.2 CM LONG, 3.0 CM IN DIAMETER AND 2213900100044 WITH 0.3 CM THICK WALLS, WAS KEPT AT A TEMPERATURE OF 2213900100045 11.8 +/- 0.4 K AND A PRESSURE OF 23.0 +/- 0.4 BARS. 2213900100046 THIS RESULTED IN A 3-HE DENSITY OF 1.48 +/- 0.05 TIMES2213900100047 E+22 NUCLEI/CM3. 2213900100048 CORRECTION .CORRECTION WAS APPLIED FOR THE EPITHERMAL NEUTRONS. 2213900100049 ERR-ANALYS (DATA-ERR) NO DETAILS GIVEN. 2213900100050 STATUS .DATA OBTAINED FROM MAIN REF. 2213900100051 HISTORY (891109C) N.O. 2213900100052 (891211E) 2213900100053 ENDBIB 51 0 2213900100054 NOCOMMON 0 0 2213900100055 ENDSUBENT 54 0 2213900199999 SUBENT 22139002 19891211 00002213900200001 BIB 3 4 2213900200002 REACTION (2-HE-3(N,G)2-HE-4,,SIG) 2213900200003 STATUS .DATA TAKEN FROM MAIN REF. 2213900200004 HISTORY (891109C) N.O. 2213900200005 (891211E) 2213900200006 ENDBIB 4 0 2213900200007 NOCOMMON 0 0 2213900200008 DATA 3 1 2213900200009 EN DATA DATA-ERR 2213900200010 KEV MICRO-B MICRO-B 2213900200011 2.4500E+01 9.2000E+00 2.0000E+00 2213900200012 ENDDATA 3 0 2213900200013 ENDSUBENT 12 0 2213900299999 ENDENTRY 2 0 2213999999999