ENTRY 22199 19930329 00002219900000001 SUBENT 22199001 19930329 00002219900100001 BIB 15 47 2219900100002 REFERENCE (J,FBS,8,23,90) 2219900100003 TITLE -NEUTRON-NEUTRON SCATTERING LENGTH IN THE REACTION 2219900100004 9BE(N,NN)8BE AT 10.3 MEV. 2219900100005 AUTHOR (K.BODEK,J.KRUG,W.LUBCKE,S.OBERMANNS,H.RUHL,M.STEINKE, 2219900100006 M.STEPHAN,D.KAMKE) 2219900100007 INSTITUTE (2GERBOC) 2219900100008 FACILITY (DYNAM) BOCHUM DYNAMITRON-TANDEM ACCELERATOR, WITH DEU-2219900100009 TERIUM BEAM PULSES OF 1.2 NS DURATION AT 5 MHZ REPE- 2219900100010 TITION RATE. 2219900100011 INC-SOURCE (D-D ) A PULSED BEAM OF 10.3 MEV (FWHM 0.6 MEV) NEU- 2219900100012 TRONS WAS PRODUCED BY THE D-D REACTION, USING A DEU- 2219900100013 TERIUM GAS TARGET. THE AVERAGE INTENSITY WAS 5E+6 PER 2219900100014 SECOND. 2219900100015 METHOD (TOF ) THE ENERGIES OF THE EMITTED NEUTRONS WERE DE- 2219900100016 TERMINED WITH TIME-OF-FLIGHT TECHNIQUES. 2219900100017 (PSD ) NEUTRON-GAMMA DISCRIMINATION WAS APPLIED. 2219900100018 DETECTOR (SCIN ) THE EMITTED NEUTRONS WERE DETECTED IN FOUR 2219900100019 NE213 LIQUID SCINTILLATORS, ARRANGED IN TWO IDENTICAL 2219900100020 ARMS AT 30 DEGREES ON EITHER SIDE OF THE BEAM. EACH 2219900100021 ARM CONSISTED OF TWO DETECTORS, ONE ANNULAR DETECTOR, 2219900100022 40 MM THICK AND WITH INNER/OUTER DIAMETERS OF 120/140 2219900100023 MM, AND ONE STANDARD DETECTOR, 180 MM IN DIAMETER BY 2219900100024 80 MM THICK. THE DETECTORS IN EITHER ARM WERE PLACED 2219900100025 AT 1 AND 2 M FROM THE SAMPLE, RESPECTIVELY. THIS 2219900100026 ARRANGEMENT ALLOWED MEASUREMENT AT LOW N-N RELATIVE 2219900100027 ENERGIES. THE DETECTORS WERE HOUSED IN MASSIVE SHIEL- 2219900100028 DINGS CONSISTING OF BRASS, STEEL AND WATER. THE 2219900100029 EFFICIENCIES OF THE DETECTORS WERE MEASURED BY THE 2219900100030 ASSOCIATED PARTICLE METHOD AS WELL AS BY UTILIZING A 2219900100031 252-CF FISSION SOURCE. A NEUTRON FLUX MONITOR WAS 2219900100032 POSITIONED IN THE BEAM DIRECTION. 2219900100033 PART-DET (N ) 2219900100034 SAMPLE .A DISC-SHAPED 2 INCH DIAMETER BY 0.5 INCH THICK METAL-2219900100035 LIC BERYLLIUM TARGET WAS USED. 2219900100036 CORRECTION .DATA WERE CORRECTED FOR DEADTIME, AND FOR BACKGROUND 2219900100037 BY FITTING A POLYNOMIAL OUTSIDE THE KINEMATICAL BAND. 2219900100038 ERR-ANALYS (DATA-ERR) TOTAL ERROR. 2219900100039 ANALYSIS .THE N-N SCATTERING LENGTH WAS DETERMINED BY COMPARING 2219900100040 THE EXPERIMENTAL DATA WITH A MONTE CARLO SIMULATION, 2219900100041 IN WHICH THE WATSON-MIGDAL MODEL WAS USED. IN THE 2219900100042 SIMULATION, THE EFFECTS OF FINITE GEOMETRY, ENERGY 2219900100043 RESOLUTION AND MULTIPLE SCATTERING IN THE TARGET, WERE2219900100044 CONSIDERED. THE EFFECTIVE RANGE PARAMETER, R-NN, WAS 2219900100045 ASSUMED TO BE 2.65 FM. 2219900100046 STATUS .DATA TAKEN FROM MAIN REF. 2219900100047 HISTORY (921220C) N.O. 2219900100048 (930329E) 2219900100049 ENDBIB 47 0 2219900100050 NOCOMMON 0 0 2219900100051 ENDSUBENT 50 0 2219900199999 SUBENT 22199002 19930329 00002219900200001 BIB 3 7 2219900200002 REACTION (0-NN-1(N,EL)0-NN-1,,AMP) SCATTERING LENGTH FOR THE 2219900200003 SINGLET NEUTRON-NEUTRON INTERACTION, DETERMINED FROM 2219900200004 THE FINAL-STATE INTERACTION OF THE TWO NEUTRONS IN THE2219900200005 EXIT CHANNEL OF THE REACTION (4-BE-9(N,2N)4-BE-8-GS). 2219900200006 STATUS .DATA TAKEN FROM MAIN REF. 2219900200007 HISTORY (921220C) N.O. 2219900200008 (930329E) 2219900200009 ENDBIB 7 0 2219900200010 NOCOMMON 0 0 2219900200011 DATA 3 1 2219900200012 EN-MIN DATA DATA-ERR 2219900200013 KEV FERMI FERMI 2219900200014 2.0000E+01 1.6500E+01 1.0000E+00 2219900200015 ENDDATA 3 0 2219900200016 ENDSUBENT 15 0 2219900299999 ENDENTRY 2 0 2219999999999