ENTRY C2635 20210614 C205C263500000001 SUBENT C2635001 20210614 C205C263500100001 BIB 9 27 C263500100002 TITLE Angular Distribution of Pions Scattered by Hydrogen C263500100003 AUTHOR (H.L.Anderson,E.Fermi,R.Martin,D.E.Nagle) C263500100004 REFERENCE (J,PR,91,155,1953) Main reference. C263500100005 #doi:10.1103/PhysRev.91.155 C263500100006 (J,PR,86,793(2),1952) Preliminary findings. C263500100007 #doi:10.1103/PhysRev.86.793.2 C263500100008 INSTITUTE (1USACHI) C263500100009 FACILITY (SYNCY,1USACHI) The Chicago synchrocyclotron. C263500100010 INC-SOURCE The pions are produced by a 450-MeV proton beam C263500100011 striking a beryllium target inside the cyclotron. C263500100012 Negative pions emitted in the forward direction are C263500100013 bent outward by the cyclotron magnetic field and C263500100014 emerge through a thin aluminum window from the vacuum C263500100015 chamber of the machine. Positive pions are obtained C263500100016 by reversing the direction of both the cyclotron and C263500100017 the deflecting magnetic fields. C263500100018 DETECTOR (SCIN) Liquid scintillation counters: The cell is C263500100019 made of clear Lucite 4-in. thick over all with C263500100020 1/16-in. thick Lucite windows. The liquid is C263500100021 phenyl cyclohexane with 3 grams per liter of terphenyl C263500100022 and 10 mg per liter of diphenyl hexatriene according C263500100023 to the prescription of Kallman. The end of the C263500100024 Lucite cell is shaped to fit the photocathode of a C263500100025 5819 tube and good optical contact is assured by a C263500100026 thin layer of clear silicone grease. C263500100027 SAMPLE Two different liquid hydrogen containers were used. C263500100028 HISTORY (20210614C) BP C263500100029 ENDBIB 27 0 C263500100030 NOCOMMON 0 0 C263500100031 ENDSUBENT 30 0 C263500199999 SUBENT C2635002 20210614 C205C263500200001 BIB 4 40 C263500200002 REACTION (1-H-1(PIP,EL)1-H-1,,DA) C263500200003 METHOD (COINC) The pion beam is defined by passing through C263500200004 two 2-in. diameter liquid scintillation counters, and C263500200005 thereafter enters the hydrogen cell. The scattered C263500200006 particles are detected by a pair of scintillation C263500200007 counters, arranged on a table to pivot around the C263500200008 central axis of the hydrogen cell. A quadruple C263500200009 coincidence is recorded when a particle passes C263500200010 through the first two counters and is scattered so as C263500200011 to pass through the second pair. The double C263500200012 coincidences of the first pair are recorded at the C263500200013 same time. The fraction of the incident beam which is C263500200014 scattered is given by the ratio of the quadruple to C263500200015 double coincidences. The hydrogen cell was designed C263500200016 for rapid insertion and removal of the liquid C263500200017 hydrogen in order to distinguish the effect of the C263500200018 hydrogen from the scattering by surrounding C263500200019 materials. The mean path length of pions traversing C263500200020 the hydrogen in these experiments was 14.4 cm. When C263500200021 the cell was filled with liquid hydrogen, the number C263500200022 of atoms/cm2 was 4.2*10**22. When the cell was empty, C263500200023 it is still contained gaseous hydrogen at liquid C263500200024 hydrogen temperature amounting to 0.07*10**22 C263500200025 atoms/cm2. The difference, 4.13*10**22, multiplied by C263500200026 the effective length of the scattering cell, gives C263500200027 5.95*10**23 H atoms/cm2. The efficiency of counters C263500200028 No. 3 and No. 4 for counting a scattered pion that C263500200029 geometrically should be accepted by both counters was C263500200030 not 100 percent because the counter efficiency was C263500200031 not perfect (98 percent), and nuclear absorption in C263500200032 the first counter and in the hydrogen cell further C263500200033 reduced the efficiency to about 93 percent. C263500200034 ERR-ANALYS (ERR-S) The probable errors are those due to C263500200035 statistics alone. Uncertainties in the beam energy C263500200036 and its pion content as well as in the estimates of C263500200037 the efficiency of detection all contribute to the C263500200038 inaccuracy of the experiment. These additional errors C263500200039 have not been added in this case because the C263500200040 statistical error was believed to be dominant. C263500200041 STATUS (TABLE) Table II, page 160 of the Phys.Rev.91,155,1953.C263500200042 ENDBIB 40 0 C263500200043 NOCOMMON 0 0 C263500200044 DATA 4 9 C263500200045 EN ANG DATA ERR-S C263500200046 MEV ADEG MB/SR MB/SR C263500200047 78.0 45.0 1.96 0.33 C263500200048 78.0 90.0 2.26 0.31 C263500200049 78.0 135.0 3.09 0.34 C263500200050 110.0 45.0 4.48 0.88 C263500200051 110.0 90.0 4.88 0.59 C263500200052 110.0 135.0 8.62 0.67 C263500200053 135.0 45.0 7.77 3.00 C263500200054 135.0 90.0 6.42 2.03 C263500200055 135.0 135.0 14.70 2.41 C263500200056 ENDDATA 11 0 C263500200057 ENDSUBENT 56 0 C263500299999 SUBENT C2635003 20210614 C205C263500300001 BIB 4 43 C263500300002 REACTION (1-H-1(PIN,EL)1-H-1,,DA) C263500300003 METHOD (COINC) The pion beam is defined by passing through C263500300004 two 2-in. diameter liquid scintillation counters, and C263500300005 thereafter enters the hydrogen cell. The scattered C263500300006 particles are detected by a pair of scintillation C263500300007 counters, arranged on a table to pivot around the C263500300008 central axis of the hydrogen cell. A quadruple C263500300009 coincidence is recorded when a particle passes C263500300010 through the first two counters and is scattered so as C263500300011 to pass through the second pair. The double C263500300012 coincidences of the first pair are recorded at the C263500300013 same time. The fraction of the incident beam which is C263500300014 scattered is given by the ratio of the quadruple to C263500300015 double coincidences. The hydrogen cell was designed C263500300016 for rapid insertion and removal of the liquid C263500300017 hydrogen in order to distinguish the effect of the C263500300018 hydrogen from the scattering by surrounding C263500300019 materials. The mean path length of pions traversing C263500300020 the hydrogen in these experiments was 14.4 cm. When C263500300021 the cell was filled with liquid hydrogen, the number C263500300022 of atoms/cm2 was 4.2*10**22. When the cell was empty, C263500300023 it is still contained gaseous hydrogen at liquid C263500300024 hydrogen temperature amounting to 0.07*10**22 C263500300025 atoms/cm2. The difference, 4.13*10**22, multiplied by C263500300026 the effective length of the scattering cell, gives C263500300027 5.95*10**23 H atoms/cm2. The efficiency of counters C263500300028 No. 3 and No. 4 for counting a scattered pion that C263500300029 geometrically should be accepted by both counters was C263500300030 not 100 percent because the counter efficiency was C263500300031 not perfect (98 percent), and nuclear absorption in C263500300032 the first counter and in the hydrogen cell further C263500300033 reduced the efficiency to about 93 percent. C263500300034 ERR-ANALYS (DATA-ERR) The errors indicated in these two cross C263500300035 sections comprise only the statistical error. Other C263500300036 sources of error are, in order of importance, the C263500300037 uncertainty in the efficiencies in the actual pion C263500300038 content and energy of the beam, and geometrical C263500300039 errors. We have estimated that the overall effect of C263500300040 these errors may amount to 10 percent, and this error C263500300041 has been combined with the statistical error in the C263500300042 fina1 results. C263500300043 (ERR-SYS,,10.) C263500300044 STATUS (TABLE) Table VII, page 162 of Phys.Rev.91,155,1953. C263500300045 ENDBIB 43 0 C263500300046 NOCOMMON 0 0 C263500300047 DATA 4 6 C263500300048 EN ANG DATA DATA-ERR C263500300049 MEV ADEG MB/SR MB/SR C263500300050 120.0 45.0 1.44 0.18 C263500300051 120.0 90.0 0.45 0.09 C263500300052 120.0 135.0 0.67 0.12 C263500300053 144.0 45.0 2.35 0.29 C263500300054 144.0 90.0 0.69 0.14 C263500300055 144.0 135.0 0.83 0.17 C263500300056 ENDDATA 8 0 C263500300057 ENDSUBENT 56 0 C263500399999 SUBENT C2635004 20210614 C205C263500400001 BIB 5 45 C263500400002 REACTION (1-H-1(PIN,PI0)0-NN-1,,DA) C263500400003 METHOD (COINC) The pion beam is defined by passing through C263500400004 two 2-in. diameter liquid scintillation counters, and C263500400005 thereafter enters the hydrogen cell. The scattered C263500400006 particles are detected by a pair of scintillation C263500400007 counters, arranged on a table to pivot around the C263500400008 central axis of the hydrogen cell. A quadruple C263500400009 coincidence is recorded when a particle passes C263500400010 through the first two counters and is scattered so as C263500400011 to pass through the second pair. The double C263500400012 coincidences of the first pair are recorded at the C263500400013 same time. The fraction of the incident beam which is C263500400014 scattered is given by the ratio of the quadruple to C263500400015 double coincidences. The hydrogen cell was designed C263500400016 for rapid insertion and removal of the liquid C263500400017 hydrogen in order to distinguish the effect of the C263500400018 hydrogen from the scattering by surrounding C263500400019 materials. The mean path length of pions traversing C263500400020 the hydrogen in these experiments was 14.4 cm. When C263500400021 the cell was filled with liquid hydrogen, the number C263500400022 of atoms/cm2 was 4.2*10**22. When the cell was empty, C263500400023 it is still contained gaseous hydrogen at liquid C263500400024 hydrogen temperature amounting to 0.07*10**22 C263500400025 atoms/cm2. The difference, 4.13*10**22, multiplied by C263500400026 the effective length of the scattering cell, gives C263500400027 5.95*10**23 H atoms/cm2. The efficiency of counters C263500400028 No. 3 and No. 4 for counting a scattered pion that C263500400029 geometrically should be accepted by both counters was C263500400030 not 100 percent because the counter efficiency was C263500400031 not perfect (98 percent), and nuclear absorption in C263500400032 the first counter and in the hydrogen cell further C263500400033 reduced the efficiency to about 93 percent. C263500400034 ERR-ANALYS (DATA-ERR) The errors indicated in these two cross C263500400035 sections comprise only the statistical error. Other C263500400036 sources of error are, in order of importance, the C263500400037 uncertainty in the efficiencies in the actual pion C263500400038 content and energy of the beam, and geometrical C263500400039 errors. We have estimated that the overall effect of C263500400040 these errors may amount to 10 percent, and this error C263500400041 has been combined with the statistical error in the C263500400042 fina1 results. C263500400043 (ERR-SYS,,10.) C263500400044 CORRECTION A very small correction has been included on account C263500400045 of the contribution of the inverse photoeffect. C263500400046 STATUS (TABLE) Table VII, page 162 of Phys.Rev.91,155,1953. C263500400047 ENDBIB 45 0 C263500400048 NOCOMMON 0 0 C263500400049 DATA 4 6 C263500400050 EN ANG DATA DATA-ERR C263500400051 MEV ADEG MB/SR MB/SR C263500400052 120.0 45.0 2.64 0.36 C263500400053 120.0 90.0 3.08 0.37 C263500400054 120.0 135.0 4.53 0.51 C263500400055 144.0 45.0 4.48 0.55 C263500400056 144.0 90.0 4.25 0.51 C263500400057 144.0 135.0 5.71 0.66 C263500400058 ENDDATA 8 0 C263500400059 ENDSUBENT 58 0 C263500499999 SUBENT C2635005 20210614 C205C263500500001 BIB 4 5 C263500500002 REACTION (1-H-1(PIN,PI0)0-NN-1,,SIG) C263500500003 ANALYSIS The results of the integration. C263500500004 ERR-ANALYS (DATA-ERR) No details on sources of uncertainties. C263500500005 STATUS (DEP,C2635005) C263500500006 (TABLE) Table VIII, page 163 of Phys.Rev.91,155,1953. C263500500007 ENDBIB 5 0 C263500500008 NOCOMMON 0 0 C263500500009 DATA 3 2 C263500500010 EN DATA DATA-ERR C263500500011 MEV MB MB C263500500012 120.0 43.4 5.4 C263500500013 144.0 61.2 7.5 C263500500014 ENDDATA 4 0 C263500500015 ENDSUBENT 14 0 C263500599999 ENDENTRY 5 0 C263599999999