ENTRY 20663 19840127 00002066300000001 SUBENT 20663001 19840127 00002066300100001 BIB 16 97 2066300100002 INSTITUTE (2GERKFK) INSTITUT FUER NEUTRONENPHYSIK UND REAKTOR- 2066300100003 TECHNIK. 2066300100004 REFERENCE (R,KFK-2191,,750806)ALSO AS THESIS ACCEPTED AT THE 2066300100005 FACULTY FOR ENGINEERING OF THE UNIVERSITY OF 2066300100006 KARLSRUHE. 2066300100007 (J,NSE,61,(4),471,7612) 2066300100008 AUTHOR (C.S.YEN) 2066300100009 TITLE -MEASUREMENTS OF THE RATIO OF THE CROSS SECTIONS OF 2066300100010 235-U FOR CAPTURE AND FISSION IN THE NEUTRON ENERGY 2066300100011 RANGE 200 EV TO 20 KEV- 2066300100012 FACILITY (CCW ) COCKCROFT-WALTON-TYPE ACCELERATOR (150 KV,50 2066300100013 MICROAMP AT A PULSELENGTH OF 0.5 MICROSEC AND 2066300100014 625 PPS REPETITIONRATE) USED FOR MAIN EXPERIMENT. 2066300100015 .THE EXPERIMENTAL REACTOR STARK OF THE INSTITUTE WAS 2066300100016 USED FOR THE CALIBRATION MEASUREMENTS. 2066300100017 INC-SOURCE (D-T ) WITH THE REACTION 3H(D,N)4HE 14 MEV NEUTRONS 2066300100018 WERE CREATED IN A TRITIUM-TITANIUM TARGET. 2066300100019 (THCOL) THE THERMAL COLUMN OF THE EXPERIMENTAL 2066300100020 REACTOR STARK OF THE INSTITUT FUER NEUTRONENPHYSIK 2066300100021 UND REAKTORTECHIK (5 W CONSTANT POWER) SUPPLIED THE 2066300100022 FLUX FOR THE CALIBRATION OF THE FISSION DETECTOR. 2066300100023 SAMPLE .FOR THE SUM-MEASUREMENT U-235 FOILS (3.57,8.92, 2066300100024 17.84X10E+20 ATOMS/CM2,93.5PC U-235) WERE PLACED AS 2066300100025 ZYLINDERS AROUND THE PROPORTIONAL COUNTER. 2066300100026 .SAMPLE AND DETECTOR FOR THE FISSION REACTION WERE 2066300100027 ONE AND THE SAME. 2066300100028 METHOD (SLODT) A SLOWING DOWN TIME SPECTROMETER IN THE FORM 2066300100029 OF A PB-PILE(2X2X2M3,99.99PC PURITY) IN CONNECTION 2066300100030 WITH THE COCKCROFT-WALTON ACCELERATOR WAS USED TO 2066300100031 CREATE A SLOW FLUX (200 EV TO 20 KEV).ENERGY- 2066300100032 DETERMINATION WAS ACHIEVED FROM THE MEASUREMENT OF 2066300100033 THE SLOWING-DOWN-TIME. 2066300100034 .DETAILED DESCRIPTION SEE REFERENCE. 2066300100035 DETECTOR (PROPC) A GAMMA-PROPORTIONAL COUNTER WAS USED TO 2066300100036 MEASURE THE SUM OF FISSION AND CAPTURE EVENTS. 2066300100037 .IT WAS EMBEDDED IN THE SAMPLES. 2066300100038 .THE CYLINDRICAL COUNTER CONSISTED OF ALMG3 OF A 2066300100039 THICKNESS OF 5.5MM WITH A TUNGSTEN ANODE (DIAMETER 2066300100040 50 MICRON).IT WAS FILLED WITH 1.5 BAR ARGON AND 2066300100041 0.02 BAR CO2.THE OUTER DIAMETER WAS 27MM, LENGTH 2066300100042 370MM, HIGHEST OPERATING VOLTAGE 2500V. 2066300100043 .THE EFFICIENCY WAS DETERMINED BY CALIBRATED GAMMA- 2066300100044 SOURCES FROM THE RADIOCHEMICAL CENTRE,AMERSHAM, 2066300100045 ENGLAND,AND WITH THE HELP OF A 24NA-SOURCE, CREATED 2066300100046 BY IRRADIATION OF 23NA FROM THE THERMAL COLUMN OF 2066300100047 THE EXPERIMENTAL REACTOR FR2. 2066300100048 (FISCH) 2 FISSION CHAMBERS(U-235,ARGON) WERE USED, TO 2066300100049 DETERMINE THE FISSION EVENT RATE. 2066300100050 .CALIBRATION IN THE THERMAL FLUX OF STARK. 2066300100051 .THERMAL FLUX FOR CALIBRATION MONITORED BY A U-235, 2066300100052 ARGON-FILLED FISSION CHAMBER. 2066300100053 .U-238 FISSION CHAMBER TO MONITOR THE TIME-DEPENDENT 2066300100054 BEHAVIOUR OF NEUTRON PRODUCTION. 2066300100055 .BF3-COUNTOR TO MONITOR THE FLUX IN THE VICINITY OF 2066300100056 THE SAMPLE. 2066300100057 ANALYSIS .AS NORMALIZING STANDARD FOR THE MEASUREMENT OF THE 2066300100058 FISSION RATE (EFFICIENCY OF FISSION CHAMBER) A 2066300100059 MEASUREMENT IN THERMAL REACTORFLUX WAS UNDERTAKEN 2066300100060 AND THE NECESSARY THERMAL FISSION AND CAPTURE CROSS 2066300100061 SECTIONS TAKEN FROM TABULATIONS (REF. NOT GIVEN). 2066300100062 .ENERGY SPECTRUM DEDUCED FROM SLOWING DOWN TIME 2066300100063 SPECTRUM.TIME AND SPACE DEPENDENT NEUTRON FLUX 2066300100064 DETERMINED VIA INSTATIONARY ENERGY-DEPENDENT 2066300100065 TRANSPORT THEORY, DIFFUSION THEORY AND FERMI-AGE 2066300100066 THEORY. 2066300100067 .THE NECESSARY CONSTANTS HAVE BEEN DETERMINED BY 2066300100068 EITHER MONTE-CARLO CALCULATIONS OR EXPERIMENTALLY. 2066300100069 .FOR DETAILS SEE REFERENCE. 2066300100070 PART-DET (G ) GAMMAS DETECTED BY PROPORTIONAL COUNTERS TO 2066300100071 GIVE THE NUMBER OF FISSION AND CAPTURE EVENTS. 2066300100072 (N ) FISSION RATE WAS DETERMINED BY USE OF A 2066300100073 NEUTRON DETECTING FISSION CHAMBER. 2066300100074 COMMENT .SYSTEMATIC ERROR POSSIBLE,SINCE ANALYSIS WAS CARRIED 2066300100075 OUT UNDER THE ASSUMPTION, THAT THE MEAN PROMPT 2066300100076 GAMMA-ENERGY PER FISSION IS INDEPENDENT OF THE 2066300100077 NEUTRON-ENERGY. 2066300100078 STATUS .ALPHA VALUES TAKEN FROM REFERENCE. 2066300100079 HISTORY (761012C) 2066300100080 (770504E) 2066300100081 (810112A) ERR-COLUMNS CHANGED. 2066300100082 (810120E) 2066300100083 CORRECTION .FOR CALIBRATION MEASUREMENTS 2066300100084 DELAYED FISSION GAMMAS, 2066300100085 NATURAL ACTIVITY OF THE URANIUM, 2066300100086 ACTIVITY DUE TO THE CREATION OF 2066300100087 FISSION PRODUCTS FROM PREVIOUS IRRADIATIONS. 2066300100088 .FOR THE MAIN EXPERIMENT 2066300100089 NATURAL RADIOACTIVITY, 2066300100090 ACTIVATION DURING DURATION OF EXPERIMENT, 2066300100091 NEUTRONS FROM PREVIOUS BEAM BURSTS,(LESS THAN 1 PC), 2066300100092 CAPTURE-GAMMA-RAYS IN PILE AND COUNTER, 2066300100093 SELF-ABSORPTION, 2066300100094 DEAD-TIME OF ANALYZER (16 MICROSEC,4PC CORRECTION), 2066300100095 NEUTRON SCATTERING IN THE GAMMA-COUNTER. 2066300100096 ERR-ANALYS (ERR-S) STATISTICAL ERRORS- LESS THAN 1 PC. 2066300100097 (ERR-T) TOTAL ERRORS BETWEEN 13 AND 20 PC. 2066300100098 .ERROR IN CALIBRATION- 3.2 PC(80PC OF TOTAL). 2066300100099 ENDBIB 97 0 2066300100100 NOCOMMON 0 0 2066300100101 ENDSUBENT 100 0 2066300199999 SUBENT 20663002 19840127 00002066300200001 BIB 3 7 2066300200002 REACTION (92-U-235(N,ABS),,ALF) 2066300200003 COMMENT .THE ENERGY RESOLUTION IS 25 PC AT 200 EV AND 50 PC 2066300200004 AT 20 KEV. 2066300200005 HISTORY (761021C) 2066300200006 (770504E) 2066300200007 (810112A) 2066300200008 (810120E) 2066300200009 ENDBIB 7 0 2066300200010 NOCOMMON 0 0 2066300200011 DATA 4 24 2066300200012 EN DATA ERR-T ERR-S 2066300200013 KEV NO-DIM NO-DIM NO-DIM 2066300200014 2.0000E-01 7.6000E-01 1.0000E-01 2066300200015 2.5000E-01 7.0000E-01 3.0000E-02 2066300200016 3.0000E-01 7.2000E-01 3.0000E-02 2066300200017 3.5000E-01 7.1000E-01 3.0000E-02 2066300200018 4.1000E-01 6.1000E-01 3.0000E-02 2066300200019 4.7000E-01 5.7000E-01 5.0000E-02 2066300200020 5.6000E-01 3.6000E-01 4.0000E-02 2066300200021 6.1000E-01 3.8000E-01 5.0000E-02 2066300200022 7.0000E-01 4.8000E-01 5.0000E-02 2066300200023 7.9000E-01 5.3000E-01 5.0000E-02 2066300200024 9.1000E-01 5.8000E-01 5.0000E-02 2066300200025 1.0500E+00 5.8000E-01 3.0000E-02 2066300200026 1.2800E+00 5.1000E-01 3.0000E-02 2066300200027 1.5400E+00 4.5000E-01 6.0000E-02 2066300200028 1.8500E+00 4.7000E-01 5.0000E-02 2066300200029 2.1100E+00 4.5000E-01 3.0000E-02 2066300200030 2.6800E+00 4.2000E-01 3.0000E-02 2066300200031 3.3700E+00 3.3000E-01 3.0000E-02 2066300200032 4.2300E+00 3.8000E-01 4.0000E-02 2066300200033 5.1700E+00 3.5000E-01 2.0000E-02 2066300200034 6.3300E+00 3.6000E-01 2.0000E-02 2066300200035 7.8200E+00 3.6000E-01 2.0000E-02 2066300200036 9.3500E+00 3.7000E-01 2.0000E-02 2066300200037 1.2760E+01 3.3000E-01 7.0000E-02 2066300200038 ENDDATA 26 0 2066300200039 ENDSUBENT 38 0 2066300299999 ENDENTRY 2 0 2066399999999