T. Yamazaki

Angular Distributions of (α, n) Reaction son Be and C

The angular distributions of neutrons from the Be 9 (α, n )C 12 reaction which leaves C 12 in its ground-, 4.43- and 9.6-MeV excited states have been measured for alpha-particle energies between 17.5 and 22.1 MeV. These angular distributions show patterns which may be interpreted in terms of direct interaction theory. The essential feature of the distributions for each neutron group seems not to change with incident energy. The angular distributions of the ground-state neutron group from the C 12 (α, n )O 15 reaction were taken at alpha particle energies from 20.0 to 21.8 MeV. Marked change of distributions with bombarding energies. is not found, while it was seen in the C 12 (α, p )N 15 reaction at the same energy range.

ELASTIC AND INELASTIC SCATTERING OF PROTONS FROM N, Ne, Mg, Si, S AND A IN THE ENERGY RANGE FROM 7.6 Mev TO 14.2 Mev

The angular distributions of protons scattered elastically and inelastically by N, Ne, Mg, Si, S and A nuclei have been studied at several values of proton energy from 7.6 to 14.2 MeV. The distribution shapes for elastic scattering show generally diffraction patterns at E p >10 MeV. While the yields of inelastic scattering corresponding to the second excited state of N 14 are appreciable at higher energies, the yields for the first excited state with T =1 are markedly low. The inelastic scatterings for the first excited states of Ne 20 , Mg 24 and Si 28 are found to change their distribution shapes appreciably with proton energy. The excitation functions of the reaction for Si 28 were also studied. The results show prominent resonance features. These results seem to support that the formation of compound nucleus plays an appreciable role in the inelastic scattering from these light nuclei, especially at the lower energy. The distribution shapes of the inelastic scattering from S 32 are fairly insensitive ...

Elastic and Inelastic Scatterings of Protons from Ti, Cr, Ni, Zn, and O at 8 to 14 MeV

The elastic and inelastic (leading to the first excited states of target nuclei) scatterings of protons by medium weight nuclei (Ti, Cr, Ni, and Zn) were studied by observing the dependence of their angular distributions on bombarding energies from 8 MeV to 14 MeV. The angular distributions of protons elastically scattered from oxygen were also measured in the same energy range. There are appreciable regularities in the elastic scatterings by medium weight nuclei as regards the dependence of their angular distributions on the bombarding energy and on the atomic number except in the case of the bombarding energy of 8 MeV. The elastic scatterings from oxygen show an anomalous behaviour at energies about 9 MeV. The angular distributions of protons inelastically scattered from medium weight nuclei can be fitted by the predictions of the direct interaction theory with Born approximation at about 14 MeV, but at the lower bombarding energies they seem not to do so, although they have the prominent forward peaks....

A FOCAL PLANE COUNTER FOR THE SPECTROGRAPH 'RAIDEN'

Abstract A focal plane counter system at Research Center for Nuclear Physics, Osaka University is described. The position detector is a gas proportional counter of one meter in length. Resistive induction grid wires and the charge division method were used for position determination. The employment of the induction wires mounted on an inclined frame made it possible to realize a fast counter with sub-millimeter position resolution for non-normal incidence (53.5° to the normal) of the particle rays.

A 1.5 m single-wire position-sensitive proportional counter for a magnetic spectrograph with a large dispersion☆

Abstract A 1.52 m single-wire position sensitive proportional counter (SWPC) is described, which has been used as a focal plane detector of the spectrograph RAIDEN installed at RCNP AVF cyclotron facility. A long SWPC system is suitable for detecting light ions with medium position resolution (1–2 mm fwhm) and with good linearity (0.1%). A four-fold counter telescope and a gate control system largely reduced the background and the peak pile-up effects in high counting rate measurements (⪅90 kHz).

The (α, p ) Reactions on Light and Medium-Weight Nuclei

Using approximates 22-Mev alpha particles the angular distributions of protons from ( alpha ,p) reactions on B/sup 10/, C/sup 12/, N/sup 14/, Na/sup 23/ , Mg/sup 24/, Pa/sup 31/, S/sup 32/, Ca/sup 40/, Sc/sup 45/, Mn/sup 55/, Fe/sup 54/, Fe/sup 56 /, and Co/sup 59/ were measured. The angular distributions on the light nuclei show diffraction-like patterns, but those on the medium-weight nuclei are peaked at forward angle and decrease monotonically with angle. These anguiar distributions are fitted with theories of a stripping reaction. At first they are compared with a theory obtained by using plane-wave approximation for wave functions of incoming alpha particles and outgoing protons. They are also compared with a theory using a simple distorted-wave approximation which fits better with the experimental results. The values of parameters in the theoretical formula show systematic differences in cases that tritons are captured by target nuclei with angular momenta 0 and 2. Some results on spectroscopic investigations of the target or residual nuclei are also discussed. The ( alpha ,p), ( alpha ,n), and (p, alpha ) reactions have a strong energy dependence near 20-Mev excitations, and above this region their energy dependences become smaller. (auth)

Line broadening and Coulomb displacement energies of the hole-state analogs in the A = 111−123 odd-mass Sn isotopes

Abstract Line broadening and orbit dependence of the Coulomb displacement energy have been observed for the 1g 9/2 , 2p 1/2 and 2p 3/2 hole-state analogs in a series of odd- A Sn isotopes. The observed widths are discussed in terms of spreading width with main contributions from mixing with the isovector monopole state as well as the escape width.

Polarization of Protons Scattered from Complex Nuclei

The experimental results for the angular dependence of polarization of elastically scattered protons from carbon at 14 and 16 MeV, and the polarization at 45° laboratory angle in the elastic scattering by 12 target nuclei at the energy of 12∼17 MeV are described. Qualitative agreement with the calculation in terms of optical potential with spin-orbit interaction is obtained for elastic scattering of protons by carbon.

Characteristics and construction of charge-division type single-wire position-sensitive proportional counter

Abstract Characteristics and construction of charge-division type single-wire position-sensitive proportional counters are described. Performances of long detectors (1.16, 1.52 and 1.82 m long and 10×30 mm 2 cross section) and short and thin detectors (32 and 43 cm long and 6×14 mm 2 cross section) are discussed.

Angular Distribution of (α,p) Reactions in Some Light Nuclei

The angular distributions of the proton groups corresponding to the lower states of the residual nuclei from the reactions C 12 (α, p )N 15 gnd ; F 19 (α, p )Ne 22 gnd, 1.28 MeV ; Al 27 (α, p )Si 30 gnd, 2.24 MeV ; and Si 28 (α, p )P 31 gnd, 1.27, 2.23, 3.13∼3.51 MeV have been measured using 22.5±0.2 MeV alpha particles. The angular distributions of the C 12 (α, p )N 15 gnd reaction are energy dependent. At 20.6 MeV steep rise in the forward angles is observed, but at 22.2 MeV the steep rise in the backward angles appears instead of the forward rise. The angular distributions of the F 19 (α, p )Ne 22 reaction are both peaked in the backward angles. The angular distributions of the Al 27 (α, p )Si 30 and the Si 28 (α, p )P 31 reactions show the diffraction-like patterns and they are interpreted with Butlers direct interaction theory.