K. Yagi

A magnetic analyzer system for the INS Tokyo synchrocyclotron

Abstract A magnetic beam analyzer system and a product-particle spectrometer of a broad-range type for a 55-MeV proton beam from the INS Tokyo synchrocyclotron are described. The beam analyzer system consists of a beam analyzer magnet and a beam cleaning magnet. A well focused and cleaned beam is obtained at the target position. The beam intensity is about 45 nA when the energy spread of the analyzed beam is 0.1%. The product-particle spectrometer is composed of a uniform-field sectorial magnet and a preceding quadrupole-magnet doublet. The spectrometer can analyze and detect simultaneously particles over an energy range from Emax to 0.67Emax. A multicounter system of an array of 200 proportional counters followed by a large plastic scintillation counter system is arranged at the focal plane of the spectrometer. The 200 proportional counters serve as position detectors, and compose counter telescopes with the scintillation counters. A momentum spectrum of analyzed particles is stored and displayed by the use of the core memory of a 1024 channel pulse height analyzer. An over-all energy resolution 0.14% and a solid angle 2 × 10−3 sr are obtained. The design, construction, testing, and operation of the magnetic analyzer system are described. Results of various calibrations, i.e. plots of dispersion, resolution, solid angle, energy measurements, etc. are given.

Level structure of 116Sn and 117Sn from (p, d), (p, t) and (p, p′) reactions

Abstract The level structure of 116 Sn has been investigated by the reactions 117 Sn(p, d), 118 Sn(p, t), and 116 Sn(p, p′) with 55 MeV incident protons and that of 117 Sn by 118 Sn(p, d) and 117 Sn(p, p′) reactions. The emitted particles have been analysed with a broad-range magnetic spectrometer. Angular distributions of emitted particles in the (p, d), (p, t) and (p, p′) reactions are analysed in terms of the DWBA method. A strong similarity between the 117 Sn(p, d) and 118 Sn(p, t) reactions is found in the excitation of all of the observed states in 116 Sn. Three new 2 + states in 118 Sn are identified both from the (p, d) and (p, t), and two excited 0 + states are established. Spectroscopic factors for 25 states extracted from the 117, 118 Sn (p, d) reactions are compared with theoretical predictions based on the pairing interaction plus quadrupole-quadrupole and octupole-octupole interactions. The agreement is reasonably good except for the 2 + states at E x ≈ 4 MeV in 116 Sn.

The single-hole states in the 50 < N ≦ 126 shell with (p, d) reactions

The neutron single-hole states in the 50 < N ≦ 82 shell have been studied by the 140Ce(p, d) reaction at 55 MeV incident energy, and those in the 82 < N ≦ 126 shell by 208, 206Pb(p, d) reactions. Emitted deuterons have been analysed with a broad-range magnetic spectrometer. Angular distributions are analysed in terms of the DWBA method. The l-values for all deuteron groups are assigned, and the jπ value and the spectroscopic factor for each state are obtained. The single-hole energies in 58139Ce81 obtained are d32 − 0; s12 − 0.25; h112 − 0.75; d52 − 1.58; g72 − 2.81 MeV (in excitation energies). These results are much different from those of the Pittsburgh group with the (d, t) reactions. The new result that the g72 state jumps below the d52state is interpreted by considering the interaction between the g72 neutrons and the last eight protons in the g72 orbit of 139Ce. The single-hole energies in 82207Pb125 are: p12 − 0; f52 − 0.57; p32 − 0.90; i132 − 1.63; f72 − 2.34; h92 − 3.41 MeV. The correspondence of the states in 205Pb with those in 207Pb is obtained from the angular distribution analysis. No evidence is found for the J-dependence of angular distributions in either the l = 3 or l = 1 Pb(p, d) transitions. The Q-dependence is discussed.

Centrality dependence of kaon yields in Si + A and Au + Au collisions at the AGS

Charged kaon production has been measured in Si+Al and Si+Au collisions at 14.6 A GeV/c, and Au+Au collisions at 11.1 A GeV/c by Experiments 859 and 866 (the E--802 Collaboration) at the BNL AGS. Invariant transverse mass spectra and rapidity distributions for both K+ and K- are presented. The centrality dependence of rapidity-integrated kaon yields is studied. Strangeness enhancement is observed as an increase in the slope of the kaon yield with the total number of participants as well as the yield per participant. The enhancement starts with peripheral Si+Al and Si+Au collisions (relative to N+N) and appears to saturate for a moderate number of participating nucleons in Si+Au collisions. It is also observed to increase slowly with centrality in Au+Au collisions, to a level in the most central Au+Au collisions that is greater than that found in central Si+A collisions. The enhancement factor for

The (3He, d) reaction on 116Sn, 118Sn and 120Sn

K^+

Analysis of Elastic Scattering of Protons by O 18 and the Energy Levels of F 19

production are 3.0 +-0.2(stat.) +-0.4(syst.) and 4.0 +-0.3(stat.) +-0.5(syst.), respectively, for the most central 7% Si+Au collisions and the most central 4% Au+Au collisions relative to N+N at the correponding beam energy.

Energy-level structure of O19, O18 and O17 investigated by (d, p) reactions with 15 MeV deuterons

Abstract The (3He, d) reaction on 116Sn, 118Sn and 120Sn has been studied with 28.2 MeV 3He particles. Deuteron spectra have been measured with a broad-range magnetic spectrograph. Information on the nuclear structure of 117Sb, 119Sb and 121Sb has been obtained from the distorted-wave Born-approximation analysis of angular distributions of various deuteron groups. The 11 2 − state has been located at 1.32, 1.37 and 1.42 MeV in 117Sb, 119Sb and 121Sb, respectively. The lowest lying 5 2 + , 7 2 + and 11 2 − states in each of the three nuclei have been found to be of rather pure single-particle character, whereas the lowest lying 1 2 + and 3 2 + states are found to be seriously mixed.

Elastic and inelastic scattering of 51.9 MeV protons by doubly even tellurium nuclei

The excitation curve of the elastic scattering of protons by O18 is analyzed using a phase shift analysis based on the R-matrix dispersion theory. Resonance energy E/sub R.(LAB), total angular momentum and parity J pi , total resonance width GAMMA , proton and alpha partial widths GAMMAp, GAMMAalpha are determined and tabulated for seven resonance levels of the compound nucleus, F/sup 19/, in the excitation energy range between 8.5 and 9.5 Mev. The two-level approximation to the R matrix is applied to analyze the shape of the excitation curve from the 680 and 846 kev resonances. The whole excitation curve in the proton energy range between 600 and l450 kev, except at small resonance anomalies, is reproduced using the resonance phase shift from the two 1/2+ resonances, the hard sphere scattering phase shift of s and p wave, and the Coulomb scattering amplitude. All other weakly excited resonances with small level widths are analyzed by the one-level approximation, assuming that they are superposed on the general trend of the excitation curve. Each resonance parameter is uniquely determined. A method of treating the finite energy resolution due to target thickness and beam energy spread is discussed. (auth)

A NUCLEAR STRUCTURE STUDY OF

Abstract The reactions O18(d, p)O19, O17(d, p)O17 were studied with 14.95 MeV deuterons and a broad range magnetic spectrograph. Absolute cross sections were measured. Angular distributions were analysed with the Butler-Born theory to determine reduced widths. In O18(d, p)O19 reactions, energies (MeV), ln and Jπ of O19 levels obtained are as follows: 0, 2, 5 2 + ; 0.096, (2), 3 2 + ; 1.468, 0, 1 2 + ; (2.612); 3.171, 1; 3.942; 4.111, (1); 5.153; 5.447, 2, 3 2 + ; (5.708); 6.282, 3, 7 2 − ; (6.480); (6.560); (6.899); 6.997; (7.117); 7.248. Assignments in parenthesis are not definitely established. From O17(d, p)O18 reactions, 4.440, 1, (3)−; 5.092; (5.375); 5.492; 6.200 are obtained. In O16(d, p)O17 reactions, intense transitions with ln = 2 to the ground 1 d 5 2 and 5.083 MeV 1 d 3 2 states and with ln = 0 to 0.871 MeV 2s state are observed, giving 1d and 2s single-particle reduced widths. A strong ln = 3 transition proceeded to 5.697 MeV ( Jπ = 7 2 − ) level, while the transition intensity for the lower 7 2 − (3.846 MeV) level was 0.18 times as weak. In O18(d, p)O19 reactions, the single-particle character of four strongly excited levels of O19 and their correspondence to those of O17 are discussed. An estimate is made of the configuration admixtures in the O18 ground state taking into account O18(d, t)O17 reaction data. The presence of 24±6% (1 f 7 2 2 ) 0 component (in intensity) is concluded. The experimentally determined admixtures are compared with shell-model calculations. The measured spectroscopic factors for the transitions to the three lowest levels of O19 can be interpreted with available shell-model wave functions of these states and of the O18 ground state.

sup 141

Abstract Measurements of elastic and inelastic proton scattering by isotopically enriched targets of 122 Te, 124 Te, 126 Te, 128 Te and 130 Te have been carried out with a 51.9 MeV proton beam. In all isotopes, differential cross sections were measured for five to nine excited states up to 3–4 MeV excitation energy. Optical-model analyses are made of the elastic scattering and best-fit optical-model parameters are obtained. Inelastic scattering data are analyzed by distorted-wave Born-approximation (DWBA) calculations using a complex form factor. Deformation parameters are obtained and compared with previously measured values. For the elastic scattering and one-phonon 2 + and 3 − states, coupled channel calculations (0 + − 2 + − 3 − ) are made. Finally, the splitting of the octupole strength, the hexadecapole vibration and the possible 2 5 pole vibration in even tellurium nuclei, are discussed.