Norihisa Kato

Nuclear structure studies of the odd-N germanium isotopes with (d, p) reactions

Abstract The (d, p) reactions on 72, 74, 76Ge were investigated with 6.02 MeV deuterons from the Kyushu University electrostatic generator. Many new levels of the residual nuclei were found up to about 4 MeV excitation energy. It was found that the (d, p) transitions with appreciable population strength proceeded predominantly via the direct reaction process. From the DWBA analysis of the cross sections and the proton angular distributions, spectroscopic factors and ln values were obtained for approximately 80 levels. A sum-rule analysis was successfully applied to the results and the emptiness of low-lying shell-model states was extracted.

High-spin states in odd-odd nuclei

High-spin states in doubly odd nuclei of 124Cs, 126Cs and 124La have been investigated by gamma ray spectroscopy. Rotational bands of pih11/2 x nuh11/2 configuration have been assigned by the block ...

A Detailed Study of Low-Lying Levels of 184W by Means of the (d,p) Reaction

Targets of separated isotopes 182 W and 183 W were bombarded with a 15 MeV deuteron beam, and outgoing protons were analyzed with a broad range magnetic spectrograph and nuclear emulsion plates. Empirical single-particle cross sections were determined from the observed cross sections and angular distributions of the reactions leading to low-lying levels of 183 W. Observed cross sections and angular distributions for the levels of 184 W were compared with the cross sections which were obtained by using the above empirical single-particle cross sections and the spectroscopic factors calculated from the pairing theory. For the members of the ground state rotational band and the γ-vibrational band in 184 W excellent agreements were obtained. Reasonably good agreements were found for six higher levels below 1800 keV, if they were interpreted as the rotational members of possible two-quasiparticle states. For the first two levels of the lowest excited K =0 + band cross sections were determined.

Transfer cross sections for 28Si + 58,62Ni

Abstract Quasielastic reaction cross sections have been measured for 28 Si + 58,62 Ni at an energy ≈ 40% above the Coulomb barrier. A strong isotope dependence in the transfer cross sections, which are dominated by the one-neutron pickup reaction, has been observed. A simple DWBA analysis can give a consistent description of the experimental results.

Spin alignment in resonant 12C+16O inelastic scattering

Abstract The spin alignment of the 3− state (6.13 MeV) of 16O from inelastic scattering of 12 C + 16 O has been measured in the energy region of known resonances around Ecm=20 MeV. The result, that the population of the m=±3 magnetic substates is enhanced on four resonances at 19.7, 20.5, 22.0 and 22.6 MeV, indicates the dominance of the aligned configuration on these resonances.

Spectroscopic study of 75Se by the (d, p) reaction

Abstract The (d, p) reaction on 74 Se was investigated with 6.0 MeV deuterons. Many new levels of the 75 Se nucleus were found up to 4.7 MeV excitation energy. From a DWBA analysis of the cross sections and the angular distributions, spectroscopic factors and l n values were obtained for forty levels. A sum rule analysis was applied to the results and the emptiness of low-lying shell model states was extracted.

The 8Be + 20Ne molecular resonances in the 12C + 16O collision

Abstract Excitation functions of the 12C(16O, 8Be)20Ne reaction leading to some low-lying states in 20Ne have been studied at Ec.m. = 22∼29 MeV. Some new resonances are identified with fluctuation analysis, and their spin and parity are determined. If we plot them on a Ec.m. vs. J(J + 1) plane together with resonances reported previously in the same reaction channel, they seem to constitute a rotational band which coincides with the elastic band of the 8 Be + 20 Ne system rather than with that of the 12 C + 16 O system. Furthermore these resonances are found to persist in having almost negligible correlation in energy with those identified in the 12 C + 16 O channels. A resonance at Ec.m. = 26.9 MeV which has been proposed by Eswaran et al. as a superdeformed shape isomeric state is not identified in the present data.

The effect of heavy-ion irradiation on an implanted-Si position-sensitive detector

Abstract Characteristics of an implanted-Si position-sensitive detector, which was designed for the Coulomb excitation experiment with NORDBALL, were investigated while varying the amount of the heavy-ion flux injected into the detector. Marked effects on the pulse height defect as well as increased reverse current were observed around a fluence of 1.5 × 109 particles/cm2. Under the same condition, severe deterioration of the position spectrum was not observed.

A detailed study of the 12C + 16O fusion reaction at Ecm = 19 to 24 MeV

Abstract Excitation functions of evaporation residues following the 12C + 16O reaction are investigated at Ecm = 19 to 24 MeV. At the resonances which have been previously identified in the 12C(16O, 8Be)20Ne two-body channel, an order of magnitude larger resonance cross section is observed in the fusion channel than that in the two-body one and is shared among a few evaporation residues (20Ne, 23Na and 24Mg). Here the resonance cross section is defined as the resonance part of the cross section on a resonance in an excitation function. It is found that for each resonance the relative intensity of the resonance cross sections of these residues is fairly well explained by assuming that they are coming from the decay of a compound nuclear resonance. It indiates that these intermediate resonances have a large probability to proceed to the formation of a more complicated configuration prior to its decay into exit channels. However, the resonant enhancement in the fusion channel is found to be weak at three energies (Ecm = 19.7, 22.0 and 22.6 MeV), where prominent resonant structures have been observed in inelastic channels. These distinct situations may be attributed to the magnitude of level density of the compound nucleus.

The phase anomaly for elastic and inelastic scattering of the 19F + 12C system

Abstract The elastic and inelastic scattering of 12C from 19F leading to the 1 2 + ( gs ), 5 2 + (197 keV ), 3 2 + (1.554 MeV ) and 9 2 + (2.780 MeV ) states has been studied at E( 12 C )=30−60 MeV . The angular distributions for the 5 2 + and 3 2 + transitions are almost in phase with those of the elastic scattering and cannot be reproduced with the DWBA and CC caculation using collective form factors.