Y. Torizuka

The deformations in 20Ne, 24Mg and 28Si from electron scattering

Abstract The data of elastic and inelastic electron scattering from 0+, 2+, 4+ states in 20Ne, 24Mg and 28Si were analyzed within a framework of the rotational model. The fits to the data are achieved by extending the Nilsson orbits to include higher oscillator states and introducing an additional Y4 deformation into the Nilsson field.

Evidence for the giant monopole resonance in 90Zr

Abstract The multipole expansion of the inelastic electron scattering continuum in 90Zr yields an E2-like structure which involves a giant monopole resonance at 17 MeV with a width of 4 MeV.

Coherent synchrotron radiation at submillimeter and millimeter wavelengths

Abstract To study the coherence effect of synchrotron radiation (SR), light emission from the Tohoku 300 MeV linac, whose energy and bunch length of electrons were 180 MeV and a few millimeters, was observed in the submillimeter and millimeter wavelength regions by using a grating spectrometer. The absolute intensity of ordinary SR in the visible region was also measured. In comparison with ordinary SR, the absolute intensity of SR in the millimeter wavelength region was enhanced by about a factor of 10 6 , which corresponded roughly to the number of electrons in one bunch. The intensity of enhanced SR showed the quadratic dependence on the beam current. The enhanced SR was strongly polarized in the electron orbital plane. The relation between the electron distribution in a bunch and the spectra of coherent SR is discussed.

The 150-MeV photon tagging system at Sendai

Abstract A description is given of the 32-channel photon tagging system recently constructed at the Laboratory of Nuclear Science. Tohoku University. Some results of photonuclear experiments performed using this system in conjunction with the high duty factor electron beam from the pulsed beam stretcher are presented.

Detector system for the analysis of scattered electrons in Tohoku University 300-MeV linac

Abstract The magnetic spectrometer to analyze the elastically and inelastically scattered electrons in combination with the Tohoku University 300-MeV electron linear accelerator is described with emphasis on its electron ladder and the data acquisition system. We employed Si(Li) semiconductor detectors combined with the conventional logic circuits for the coincidence counter telescopes and also for the other circuitry system. Three detector pieces were used per channel and a total of 33 such channels were employed. Data was collected during the beam pulse intervals of about 3.3 msec, after each pulse. The stability of the counting efficiency of the detector channel and the angular constancy of the effective solid angle of the spectrometer were examined.

SSTR — the 150 MeV pulse stretcher of Tohoku University

Abstract This paper describes the Tohoku University 150 MeV pulse stretcher and its operation and use. The ring accepts a pulsed beam from the electron linac and produces a continuous current. An extracted beam of 1 μA has been obtained with a duty factor of 80%. The energy spread of the extracted beam was measured to be 0.2%. The stretcher supplies this continuous beam for use in coincidence experiments. Presently (e, e′p) and tagged photon experiments are being successfully performed.

Elastic electron scattering from the M7 magnetization density of 51V

Abstract Cross sections of the elastic scattering of electrons from 51 V have been measured at 155° in the q region of 1.2 to 2.4 fm −1 . The value of the M7 magnetic moment 505±30 μ N fm 6 and the oscillator parameter b =1.86±0.04 fm have been deduced.

Measurements of 10B(γ, p) and 10B(γ, pn) Cross Sections at Eγ=66∼103 MeV

Measurements of the cross sections of 10 B(γ, p) and 10 B(γ, pn) with tagged photons have been performed at E γ =66∼103 MeV. The results of both the 10 B(γ, p) and (γ, pn) measurement show the dominance of a two-nucleon photoabsorption process in this energy region.

Performance of an energy compressing system for the Tohoku 300 MeV Linac

Abstract An energy compressing system has been installed in the Tohoku 300 MeV Electron Linac. The electron beam current within an energy resolution of 0.15% was increased by about 20 times.

Longitudinal electroexcitation of the low-lying states in 42Ca and 44Ca

Abstract The form factors in electron scattering have been measured for 2 + , 3 − and 5 − states up to 7 MeV excitation in 42 Ca and 44 Ca. The range of the incident electron energy and scattering angles were 62.5–250 MeV at relatively forward angles, over the momentum transfer from 0.4–1.8 fm − . The reduced transition probabilities B (E l ) for these states were determined using Tassie-type and shell-model-type transition densities. It is shown that the characteristics and the differences of the observed 2 + 1 and 2 + 2 form factors in 42 Ca and 44 Ca are explained by deformation effect and the coexistence model was well verified in 42 Ca. The form factor of the 6.1 MeV transition in 42 Ca may be interpreted as an isoscalar dipole transition by its E3-like q -dependence similar to those in the self-conjugate nucleus 40 Ca, and the isoscalar E1 transition density is deduced.