ENTRY 14749 20220314 14981474900000001 SUBENT 14749001 20220314 14981474900100001 BIB 13 33 1474900100002 TITLE Disintegration of Helium by 90-MeV Neutrons 1474900100003 AUTHOR (P.E.Tannenwald) 1474900100004 REFERENCE (J,PR,89,508,1953) Main reference. 1474900100005 #doi:10.1103/PhysRev.89.508 1474900100006 (J,PR,87,(L3),205,1952) Preliminary results. 1474900100007 #doi:10.1103/PhysRev.87.179 1474900100008 REL-REF (I,,P.Tannenwald,J,BAP,27,54(1),1952) Cloud chamber 1474900100009 description. 1474900100010 INSTITUTE (1USABRK) 1474900100011 FACILITY (CYCLO,1USABRK) 184-inch Berkeley cyclotron. 1474900100012 INC-SOURCE (D-BE) The 90-MeV neutrons produced in the stripping 1474900100013 process by bombarding a 2-inch thick beryllium target 1474900100014 with 190-MeV deuterons. 1474900100015 DETECTOR (TRD) A 22-inch cloud chamber filled with helium gas 1474900100016 and operated in a pulsed magnetic field of 22000 gauss.1474900100017 METHOD The particles were identified by curvature and relative1474900100018 ionization, or by change of curvature with range when 1474900100019 they stopped in the chamber. 1474900100020 ANALYSIS A weighting factor was computed for each one and 1474900100021 two-prong star analyzed, which corrects for events 1474900100022 which were too slanted to be measured. Since the 1474900100023 number of He3,s was uncertain because they could not 1474900100024 be distinguished from He4's when the track did not 1474900100025 end in the chamber, the ratio of He3/pt events was 1474900100026 assumed to be the same as the ratio of sigma nn/sigma 1474900100027 np at 90 MeV. The total number of events, for 1474900100028 neutrons above 20 MeV, was normalized to the 1474900100029 interpolated n-He4 total cross section of 0.19 b. 1474900100030 MONITOR (2-HE-4(N,TOT),,SIG) 1474900100031 MONIT-REF ((MONIT)11146001,L.J.Cook+,J,PR,75,7,1949) Value was 1474900100032 deduced in the current work using H,D,Li, and Be 1474900100033 cross sections from 11146 plotted vs. A**(2/3). 1474900100034 HISTORY (20220314C) BP 1474900100035 ENDBIB 33 0 1474900100036 COMMON 2 3 1474900100037 EN-MEAN MONIT 1474900100038 MEV B 1474900100039 90.0 0.19 1474900100040 ENDCOMMON 3 0 1474900100041 ENDSUBENT 40 0 1474900199999 SUBENT 14749002 20220314 14981474900200001 BIB 4 16 1474900200002 REACTION (2-HE-4(N,EL)2-HE-4,,SIG,,SPA) 1474900200003 ANALYSIS The angular distribution of scattered neutrons in the 1474900200004 elastic collisions fits a Gaussian centered on the 1474900200005 forward direction for incident neutrons with energies 1474900200006 greater than 40 MeV and is roughly isotropic for 1474900200007 neutrons below 40 MeV. 1474900200008 ERR-ANALYS (ERR-S) The statistical probable errors based on the 1474900200009 number of events actually analyzed. For each quantity 1474900200010 making up the 484 elastic events a statistical 1474900200011 probable error can be associated based on the number 1474900200012 of events actually measured. But it is more realistic 1474900200013 to consider the magnitude of the extrapolation that 1474900200014 had to be made for missed tracks and the uncertainty 1474900200015 in the 80.8 assumed He3 events, and consequently a 1474900200016 probable error of +-60 was assigned to the 484 recoils.1474900200017 STATUS (TABLE) Table III, page 512 of the main reference. 1474900200018 ENDBIB 16 0 1474900200019 NOCOMMON 0 0 1474900200020 DATA 2 1 1474900200021 DATA ERR-S 1474900200022 MB MB 1474900200023 96.0 17.0 1474900200024 ENDDATA 3 0 1474900200025 ENDSUBENT 24 0 1474900299999 SUBENT 14749003 20220314 14981474900300001 BIB 3 11 1474900300002 REACTION (2-HE-4(N,N+P)1-H-3,,SIG,,SPA) 1474900300003 ERR-ANALYS (ERR-S) The statistical probable errors based on the 1474900300004 number of events actually analyzed. For each quantity 1474900300005 making up the 484 elastic events a statistical 1474900300006 probable error can be associated based on the number 1474900300007 of events actually measured. But it is more realistic 1474900300008 to consider the magnitude of the extrapolation that 1474900300009 had to be made for missed tracks and the uncertainty 1474900300010 in the 80.8 assumed He3 events, and consequently a 1474900300011 probable error of +-60 was assigned to the 484 recoils.1474900300012 STATUS (TABLE) Table III, page 512 of the main reference. 1474900300013 ENDBIB 11 0 1474900300014 NOCOMMON 0 0 1474900300015 DATA 2 1 1474900300016 DATA ERR-S 1474900300017 MB MB 1474900300018 42.0 6.0 1474900300019 ENDDATA 3 0 1474900300020 ENDSUBENT 19 0 1474900399999 SUBENT 14749004 20220314 14981474900400001 BIB 3 11 1474900400002 REACTION (2-HE-4(N,D)1-H-3,,SIG,,SPA) 1474900400003 ERR-ANALYS (ERR-S) The statistical probable errors based on the 1474900400004 number of events actually analyzed. For each quantity 1474900400005 making up the 484 elastic events a statistical 1474900400006 probable error can be associated based on the number 1474900400007 of events actually measured. But it is more realistic 1474900400008 to consider the magnitude of the extrapolation that 1474900400009 had to be made for missed tracks and the uncertainty 1474900400010 in the 80.8 assumed He3 events, and consequently a 1474900400011 probable error of +-60 was assigned to the 484 recoils.1474900400012 STATUS (TABLE) Table III, page 512 of the main reference. 1474900400013 ENDBIB 11 0 1474900400014 NOCOMMON 0 0 1474900400015 DATA 2 1 1474900400016 DATA ERR-S 1474900400017 MB MB 1474900400018 13.3 2.5 1474900400019 ENDDATA 3 0 1474900400020 ENDSUBENT 19 0 1474900499999 SUBENT 14749005 20220314 14981474900500001 BIB 3 11 1474900500002 REACTION (2-HE-4(N,2N+P)1-H-2,,SIG,,SPA) 1474900500003 ERR-ANALYS (ERR-S) The statistical probable errors based on the 1474900500004 number of events actually analyzed. For each quantity 1474900500005 making up the 484 elastic events a statistical 1474900500006 probable error can be associated based on the number 1474900500007 of events actually measured. But it is more realistic 1474900500008 to consider the magnitude of the extrapolation that 1474900500009 had to be made for missed tracks and the uncertainty 1474900500010 in the 80.8 assumed He3 events, and consequently a 1474900500011 probable error of +-60 was assigned to the 484 recoils.1474900500012 STATUS (TABLE) Table III, page 512 of the main reference. 1474900500013 ENDBIB 11 0 1474900500014 NOCOMMON 0 0 1474900500015 DATA 2 1 1474900500016 DATA ERR-S 1474900500017 MB MB 1474900500018 15.0 2.5 1474900500019 ENDDATA 3 0 1474900500020 ENDSUBENT 19 0 1474900599999 SUBENT 14749006 20220314 14981474900600001 BIB 3 11 1474900600002 REACTION (2-HE-4(N,N+D)1-H-2,,SIG,,SPA) 1474900600003 ERR-ANALYS (ERR-S) The statistical probable errors based on the 1474900600004 number of events actually analyzed. For each quantity 1474900600005 making up the 484 elastic events a statistical 1474900600006 probable error can be associated based on the number 1474900600007 of events actually measured. But it is more realistic 1474900600008 to consider the magnitude of the extrapolation that 1474900600009 had to be made for missed tracks and the uncertainty 1474900600010 in the 80.8 assumed He3 events, and consequently a 1474900600011 probable error of +-60 was assigned to the 484 recoils.1474900600012 STATUS (TABLE) Table III, page 512 of the main reference. 1474900600013 ENDBIB 11 0 1474900600014 NOCOMMON 0 0 1474900600015 DATA 2 1 1474900600016 DATA ERR-S 1474900600017 MB MB 1474900600018 7.0 1.5 1474900600019 ENDDATA 3 0 1474900600020 ENDSUBENT 19 0 1474900699999 SUBENT 14749007 20220314 14981474900700001 BIB 3 11 1474900700002 REACTION (2-HE-4(N,3N+P)1-H-1,,SIG,,SPA) 1474900700003 ERR-ANALYS (ERR-S) The statistical probable errors based on the 1474900700004 number of events actually analyzed. For each quantity 1474900700005 making up the 484 elastic events a statistical 1474900700006 probable error can be associated based on the number 1474900700007 of events actually measured. But it is more realistic 1474900700008 to consider the magnitude of the extrapolation that 1474900700009 had to be made for missed tracks and the uncertainty 1474900700010 in the 80.8 assumed He3 events, and consequently a 1474900700011 probable error of +-60 was assigned to the 484 recoils.1474900700012 STATUS (TABLE) Table III, page 512 of the main reference. 1474900700013 ENDBIB 11 0 1474900700014 NOCOMMON 0 0 1474900700015 DATA 2 1 1474900700016 DATA ERR-S 1474900700017 MB MB 1474900700018 0.8 0.4 1474900700019 ENDDATA 3 0 1474900700020 ENDSUBENT 19 0 1474900799999 SUBENT 14749008 20220314 14981474900800001 BIB 3 11 1474900800002 REACTION (2-HE-4(N,2N)2-HE-3,,SIG,,SPA) 1474900800003 ANALYSIS As has been mentioned before, it was impossible to 1474900800004 determine whether a single track was He3 or He4 when 1474900800005 it did not end in the chamber. In order to estimate 1474900800006 what fraction of all the single tracks was He'3, some 1474900800007 assumption must be made regarding the He3 formation 1474900800008 mechanism. Corrections, in the present investigation 1474900800009 the ratio of He3 to pt events is assumed to be sigma 1474900800010 nn /sigma np = sigma pp /sigma np = 1/3, which leads 1474900800011 to about three times the He3 cross section. 1474900800012 STATUS (TABLE) Table III, page 512 of the main reference. 1474900800013 ENDBIB 11 0 1474900800014 NOCOMMON 0 0 1474900800015 DATA 1 1 1474900800016 DATA 1474900800017 MB 1474900800018 16.0 1474900800019 ENDDATA 3 0 1474900800020 ENDSUBENT 19 0 1474900899999 SUBENT 14749009 20220314 14981474900900001 BIB 4 13 1474900900002 REACTION ((2-HE-4(N,NON),,SIG,,SPA,DERIV)/ 1474900900003 (2-HE-4(N,TOT),,SIG,,SPA,DERIV)) 1474900900004 ANALYSIS Non-elastic scattering and total cross sections derived1474900900005 by summing measured cross sections over various 1474900900006 channels 1474900900007 ERR-ANALYS (DATA-ERR) No details on sources of uncertainties. 1474900900008 STATUS (DEP,14749003) 1474900900009 (DEP,14749004) 1474900900010 (DEP,14749005) 1474900900011 (DEP,14749006) 1474900900012 (DEP,14749007) 1474900900013 (DEP,14749008) 1474900900014 (TABLE) page 512 of the main reference. 1474900900015 ENDBIB 13 0 1474900900016 NOCOMMON 0 0 1474900900017 DATA 2 1 1474900900018 DATA DATA-ERR 1474900900019 NO-DIM NO-DIM 1474900900020 0.49 0.07 1474900900021 ENDDATA 3 0 1474900900022 ENDSUBENT 21 0 1474900999999 ENDENTRY 9 0 1474999999999