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