ENTRY 21500 19800429 00002150000000001 SUBENT 21500001 19800429 00002150000100001 BIB 16 62 2150000100002 INSTITUTE (2GERMUN) 2150000100003 REFERENCE (J,NUK,10,58,6707) 2150000100004 (P,EANDC(E)-76U,43,6701) 2150000100005 AUTHOR (E.FEICHT,H.VONACH) 2150000100006 TITLE -MEASUREMENTS OF (N,2N) CROSS SECTIONS USING 2150000100007 THE FERMI WATER-TANK METHOD.- (IN GERMAN).- 2150000100008 FACILITY (CCW ) 150 KEV COCKCROFT-WALTON ACCELERATOR, 2150000100009 BUILD BY HEUSCH. 2150000100010 INC-SOURCE (D-T ) DEUTERON-TRITIUM REACTION. TRITIUM TARGET 2150000100011 SUPPLIED BY DR.H.FABIAN, VIENNA. 2150000100012 SAMPLE .NATURAL BISMUTH, HOLLOW SPHERE, INNER DIAM 2.5 CM, 2150000100013 OUTER DIAM 7.4 CM. 2150000100014 METHOD .FERMI WATER TANK METHOD. THE NEUTRON SOURCE IS 2150000100015 IN THE CENTRE OF A SPHERICAL SAMPLE. NEUTRONS 2150000100016 COMING OUT OF THIS SAMPLE ARE SLOWED DOWN IN 2150000100017 THE SURROUNDING WATER. THE SPATIAL DISTRIBUTION 2150000100018 OF THESE SLOWED DOWN NEUTRONS IS MEASURED BY 2150000100019 GOLD ACTIVATION ANALYSIS. NEUTRONS ORIGINATING 2150000100020 FROM NONELASTIC REACTIONS HAVE A MEAN ENERGY OF 2150000100021 ABOUT 2 MEV. 2150000100022 THE ORIGINAL NEUTRON FLUX IS MONITORED BY AN 2150000100023 ACTIVATION MEASUREMENT OF THE NEUTRONS WHICH ARE 2150000100024 ELASTICALLY SCATTERED FROM THE SAMPLE OR HAVE 2150000100025 LEFT IT WITHOUT ANY REACTION (ENERGY 14 MEV) 2150000100026 HEREFORE ALUMINIUM FOILS ARE USED (WHICH HAVE 2150000100027 A TRESHOLD, ELIMINATING THE NEUTRONS ORIGINATING 2150000100028 FROM NONELASTIC REACTIONS). USING THESE DATA AND 2150000100029 THE EQUATIONS DERIVED IN THE TEXT, THE (N,2N) 2150000100030 CROSS SECTION CAN BE DERIVED FROM THE CROSS 2150000100031 SECTION FOR THE NONELASTIC NEUTRON PRODUCING 2150000100032 REACTIONS. 2150000100033 DETECTOR (MTANK) SEE METHOD. THE FOILS ARE BETA COUNTED 2150000100034 WITH A C-H(4)-GAS-FLOW DETECTOR. 2150000100035 DIMENSIONS OF THE TANK ARE 2 * 3 * 1.5 M**3. 2150000100036 MONITOR (83-BI-209(N,X)0-NN-1,EM,SIG) NEUTRON EMISSION 2150000100037 CROSS SECTION. (BOTH (N,2N) AND (N,INL)). 2150000100038 PART-DET (B ) BETA PARTICLES OF ACTIVATED FOILS. 2150000100039 COMMENT .2 AU FOILS OF 180 MG/CM*CM WERE USED AND 4 AL 2150000100040 FOILS OF 265 MG/CM*CM. 2150000100041 STATUS (NDD ) DATA TAKEN FROM NEUDADA. 2150000100042 HISTORY (800404T) G.C. 2150000100043 (800429E) 2150000100044 CORRECTION .INFLUENCE OF ELASTIC SCATTERING ON THE PATH LENGTH 2150000100045 WITHIN THE SAMPLE TRAVERSED BY THE 14 MEV NEUTRONS 2150000100046 .(N,2N) REACTIONS BY NEUTRONS ELASTICALLY SCATTERED 2150000100047 BACK INTO THE SAMPLE BY THE WATER OF THE TANK. 2150000100048 .HOLE IN THE SAMPLE TO LET THE DEUTERONS COME IN. 2150000100049 THIS IS DONE BY INTRODUCING AN EFFECTIVE DENSITY OF 2150000100050 THE SPHERE MATERIAL. 2150000100051 .NEUTRON ABSORPTION BY THE OXYGEN ATOMS IN THE WATER. 2150000100052 .BACKGROUND IN THE BETA COUNTING MEASUREMENTS. 2150000100053 .ACTIVITY PRESENT IN THE ACTIVATION FOILS BEFORE THE 2150000100054 ACTIVATION. 2150000100055 .ACTIVATION OF THE GOLD FOILS BY RESONANCE NEUTRONS 2150000100056 (BY MEASUREMENT OF CADMIUM RATIOS). 2150000100057 ERR-ANALYS .ERROR OF 3.4 PERC FROM NORMALIZATION TO THE SAME 2150000100058 INCOMING NEUTRON FLUX AND FROM CADMIUM RATIO 2150000100059 MEASUREMENTS, 0.8 PERCENT FROM THE PATH LENGTH 2150000100060 CORRECTION, 1 PERCENT FOR THE EFFECTIVE DENSITY 2150000100061 CORRECTION, 0.4 PERCENT FOR THE CORRECTION FOR 2150000100062 THE REACTIONS WITH OXYGEN, 1 PERCENT FOR OTHERS. 2150000100063 TOTAL ERROR OF 12 PERCENT. 2150000100064 ENDBIB 62 0 2150000100065 NOCOMMON 0 0 2150000100066 ENDSUBENT 65 0 2150000199999 SUBENT 21500002 19800429 00002150000200001 BIB 3 4 2150000200002 REACTION (83-BI-209(N,2N)83-BI-208,,SIG) 2150000200003 STATUS (NDD ) DATA TAKEN FROM NEUDADA. 2150000200004 HISTORY (800408T) G.C. 2150000200005 (800429E) 2150000200006 ENDBIB 4 0 2150000200007 NOCOMMON 0 0 2150000200008 DATA 5 1 2150000200009 EN MONIT MONIT-ERR DATA DATA-ERR 2150000200010 MEV B B B B 2150000200011 1.4100E+01 2.5500E+00 2.0000E-02 2.2500E+00 2.5000E-01 2150000200012 ENDDATA 3 0 2150000200013 ENDSUBENT 12 0 2150000299999 ENDENTRY 2 0 2150099999999