ENTRY 21580 19810408 00002158000000001 SUBENT 21580001 19810408 00002158000100001 BIB 16 95 2158000100002 INSTITUTE (2GERBON) INSTITUT FUER STRAHLEN- UND KERNPHYSIK. 2158000100003 W.V.W.,B.G.M,W.R.,K.E. 2158000100004 (2NEDAMS) NATUURKUNDIG LABORATORIUM. 2158000100005 J.B. 2158000100006 REFERENCE (J,NP/A,329,1,141,791008) 2158000100007 (J,PL/B,80,3,187,790101) 2158000100008 AUTHOR (W.VON WITSCH,B.GOMEZ MORENO,W.ROSENSTOCK, 2158000100009 K.ETTLING,J.BRUINSMA) 2158000100010 TITLE -DETERMINATION OF THE NEUTRON-NEUTRON SCATTERING 2158000100011 LENGTH FROM THE H-2(N,NP)N REACTION AT BOMBARDING 2158000100012 ENERGIES BETWEEN 17 MEV AND 27 MEV.- 2158000100013 FACILITY (ISOCY,2GERBON) ISOCHRONOUS CYCLOTRON. 2158000100014 INC-SOURCE (D-D ) 28 MEV DEUTERON BEAM (10 MICRO-AMPERES) 2158000100015 ONTO A LIQUID NITROGEN COOLED HIGH PRESSURE 2158000100016 (90 BAR) DEUTERIUM GAS TARGET. 2158000100017 NEUTRONS EMITTED IN FORWARD DIRECTION WERE 2158000100018 COLLIMATED TO PRODUCE A BEAM OF 22 MM DIAM WITH 2158000100019 AN INTENSITY OF 1.65E+06 NEUTRONS/MEV*CM*CM*S 2158000100020 ON THE TARGET FOR THE HIGHEST ENERGIES. 2158000100021 SAMPLE .C-D(2) TARGET, 50 MG/CM*CM THICK IN THE FIRST, 2158000100022 AND 30 MG/CM*CM IN THE SECOND AND THIRD PART OF 2158000100023 THE EXPERIMENT. IT HAD THE FORM OF AN ELLIPSE 2158000100024 WITH HALF-AXES OF 15 MM AND 10 MM, RESPECTIVELY, 2158000100025 SO THAT IT APPEARED AS A CIRCULAR DISC TO THE BEAM. 2158000100026 METHOD (TOF ) TO DETERMINE THE INCOMING NEUTRON ENERGY, 2158000100027 AND TO DETERMINE THE PROTON ENERGY (TO DISCRIMINATE 2158000100028 AGAINST DEUTERONS AND OTHER CHARGED PARTICLES). 2158000100029 (PHD ) PULSE-HEIGHT DISCRIMINATION TO DO THIS 2158000100030 REJECTION OF OTHER CHARGED PARTICLES ON THE 2158000100031 BASIS OF THEIR TOF. 2158000100032 (REC ) PROTON RECOILS ARE MEASURED TO MONITOR 2158000100033 THE INCOMING NEUTRON FLUX. 2158000100034 (PSD ) PULSE SHAPE DISCRIMINATION IS USED TO 2158000100035 DISTINGUISH NEUTRONS FROM GAMMA-RAYS. 2158000100036 DETECTOR (TELES) PROTON RECOIL TELESCOPE TO MONITOR THE 2158000100037 INCOMING NEUTRON FLUX. 2158000100038 (COIN,SCIN,SCIN) BREAK-UP NEUTRONS ARE DETECTED AT 2158000100039 50 DEGREES WITH A WELL SHIELDED NE213 SCINTILLATOR 2158000100040 IN COINCIDENCE WITH BREAK UP PROTONS EMITTED AT 48 2158000100041 DEGREES ON THE OPPOSITE SIDE OF THE BEAM. THESE 2158000100042 PROTONS ARE DETECTED IN A NE104 PLASTIC 2158000100043 SCINTILLATOR. 2158000100044 THE NE104 SCINTILLATOR HAD A DIAM OF 110 MM. 2158000100045 THE NE213 SCINTILLATOR WAS 76 MM THICK, WITH A 2158000100046 DIAMETER OF 127 MM. 2158000100047 (COIN,SCIN,SOLST) IN A 2ND+3TH PART OF THE EXPERIMENT 2158000100048 THE NE104 PLASTIC SCINTILLATOR WAS REPLACED WITH 2158000100049 SIX 450 MM*MM SI SURFACE BARRIER DETECTORS, MOUNTED 2158000100050 IN TWO VERTICAL ROWS AT 47. AND 49. DEGR 2158000100051 RESPECTIVELY, IN EACH OF WHICH THE THREE DETECTORS 2158000100052 WERE ELECTRONICALLY TREATED AS ONE. 2158000100053 (SCIN ) THE PROTONS PASS THROUGH A SCINTILLATION 2158000100054 FOIL OF 1.5 MG/CM*CM TO PRODUCE THE TOF START 2158000100055 SIGNALS FOR THE PROTON ENERGY MEASUREMENT. 2158000100056 ANALYSIS .IS DONE BY FITTING THE RESULTS OF MONTE CARLO 2158000100057 CALCULATIONS OF THE PROCESS IN POINT GEOMETRY 2158000100058 FOR DIFFERENT POSSIBLE VALUES OF THE SCATTERING 2158000100059 LENGTH TO THE EXPERIMENTAL DATA. 2158000100060 FOR MORE DETAILS ABOUT THESE MONTE CARLO 2158000100061 CALCULATIONS, SEE NP/A,329,1,141. 2158000100062 PART-DET (P ) BREAK-UP PROTONS. 2158000100063 (N ) BREAK UP NEUTRONS. 2158000100064 COMMENT .THE EFFECTIVE RANGE WAS KEPT FIXED AT ITS CHARGE 2158000100065 SYMMETRIC VALUE OF 2.8 FM. VARIATION OF THIS VALUE 2158000100066 BETWEEN 2.5 AND 3.5 FM DOES NOT CHANGE THE 2158000100067 SCATTERING LENGTH BY MORE THAN 0.1 FM. 2158000100068 STATUS .TEXT, MAIN REFERENCE. 2158000100069 HISTORY (800708C) G.C. 2158000100070 (800718E) 2158000100071 CORRECTION .ACCIDENTAL COINCIDENCES. 2158000100072 ERR-ANALYS .THE ERROR CORRESPONDS TO LEAST CHI-SQUARE + 1 2158000100073 OF THE FIT OF THE PROJECTED COINCIDENCE SPECTRUM. 2158000100074 IT INCLUDES STATISTICS AS WELL AS OTHER 2158000100075 EXPERIMENTAL UNCERTAINTIES WHOSE INFLUENCE UPON 2158000100076 THE FINAL RESULT WAS CHECKED WITH MONTE CARLO 2158000100077 CALCULATIONS. 2158000100078 A DETAILED ANALYSIS IS GIVEN IN TABLE 1 OF THE 2158000100079 MAIN REFERENCE - 2158000100080 ----------------------------------------------- 2158000100081 SOURCE OF ERROR DELTA(A) 2158000100082 ----------------------------------------------- 2158000100083 STATISTICS (EXP.) 0.50 FM 2158000100084 STATISTICS (MONTE CARLO) 0.10 FM 2158000100085 THETA-N ( +-0.1 DEGR) 0.10 FM 2158000100086 THETA-P ( +-0.1 DEGR) 0.10 FM 2158000100087 RELAT. NEUTRON DETECT. EFFICIENCY 0.15 FM 2158000100088 TIME RESOLUTION NEUTRON DETECTOR 0.10 FM 2158000100089 NEUTRON LOSS DUE TO INTERACTIONS 2158000100090 AND SCATTERING 0.15 FM 2158000100091 ENERGY LOSS OF PROTONS ( +- 2158000100092 10. PERCENT) 0.10 FM 2158000100093 MULTIPLE SCATTERING OF PROTONS 0.05 FM 2158000100094 ----------------------------------------------- 2158000100095 TOTAL 0.60 FM 2158000100096 ----------------------------------------------- 2158000100097 ENDBIB 95 0 2158000100098 NOCOMMON 0 0 2158000100099 ENDSUBENT 98 0 2158000199999 SUBENT 21580002 19810408 00002158000200001 BIB 3 6 2158000200002 REACTION (0-NN-1(N,EL)0-NN-1,,AMP) SCATTERING LENGTH FOR 2158000200003 THE NEUTRON-NEUTRON INTERACTION IN THE NEUTRON 2158000200004 INDUCED BREAK UP OF DEUTERIUM (1-H-2(N,2N)1-H-1). 2158000200005 STATUS .TEXT, MAIN REFERENCE. 2158000200006 HISTORY (800708C) G.C. 2158000200007 (800718E) 2158000200008 ENDBIB 6 0 2158000200009 NOCOMMON 0 0 2158000200010 DATA 4 1 2158000200011 EN-MIN EN-MAX DATA DATA-ERR 2158000200012 MEV MEV FERMI FERMI 2158000200013 2.1000E+01 2.7000E+01-1.6900E+01 6.0000E-01 2158000200014 ENDDATA 3 0 2158000200015 ENDSUBENT 14 0 2158000299999 ENDENTRY 2 0 2158099999999