M. Nagashima

Observation of Muonic X-rays of Cosmic-Ray Muons Stopped in Al and Fe Targets

We successfully measured muonic X-rays of cosmic-ray muons stopped in Al and Fe targets. In order to identify the events that incoming cosmic-ray muons were stopped in the targets, a coincidence and anticoincidence system of three plastic scintillators was used. The X-rays associated with the atomic muon captures were measured with germanium detectors. Measurements using the Al and Fe targets were carried out for 33 and 16 days, respectively. A sufficient number of muonic X-ray events for identifying the elemental compositions of the target materials were clearly observed. This technique provides a means of nondestructive elemental analysis that does not require the use of particle accelerators.

Pygmy dipole resonance and dipole polarizability in 90Zr

Electric dipole (E1) reduced transition probability B(E1) of 90Zr was obtained by the inelastic proton scattering near 0 degrees using a 295 MeV proton beam and multipole decomposition analysis of the angular distribution by the distorted-wave Born approximation with the Hartree-Fock plus random-phase approximation model and inclusion of El Coulomb excitation, and the E1 strength of the pygmy dipole resonance was found in the vicinity of the neutron threshold in the low-energy tail of the giant dipole resonance. Using the data, we plan to determine the precise dipole polarizability αD which is defined as an inversely energy-weighted sum value of the elecrric dipole strength. The dipole polarizability is expected to constrain the symmetry energy term of the neutron matter equation of state. Thus systematical measurement of the dipole polarizability is important.

Electromagnetic Moments of Proton-Rich {sup 28}P and Decomposition of Its Spin

The magnetic moment of 28P(Iπ = 3+, T1/2 = 270.3 ms) has been measured precisely by means of β‐NMR technique. The obtained magnetic moment is |μ(28P)| = 0.3115 (34) μN. Combined with the magnetic moment of its mirror partner 28Al, the nuclear spin I = 3 is decomposed into its 4 components. The measurement of the Q moment has also been tried. From the preliminary NQR spectrum, it was found that the quadrupole coupling constant eqQ/h may be slightly larger than the prediction, which may show enhancement of the Q moment.