S. Morinobu

The QDMDQ magnetic spectrograph “Raiden” (I)-design and construction☆

Abstract A new magnetic spectrograph, named RAIDEN, for charged-particle spectroscopy was constructed and succesfully put into operation in the fall of 1976. The spectrograph principally consists of two dipoles, two quadrupoles and a multipole element arranged in the QDMDQ form. The specifications are: resolving power of p / δp = 2 × 10 4 , maximum acceptance solid angle of 13 msr, and maximum particle rigidity of 24 kG m. Great emphasis was placed on the multipole element to achieve dynamic focusing control.

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).

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.

Radiochemistry and secondary reactions for the diagnostics of laser‐driven fusion plasmas

Radiochemical measurements have been developed for the diagnostics of laser‐driven implosion plasmas. The excellent calibration for neutron‐yield measurement has been done using β‐γ coincidence technique. The multiactivable tracer method has been examined for measuring the pusher areal density by means of a high‐purity germanium detector. The first experimental success of the secondary nuclear fusion reaction method is also demonstrated for the direct measurement of the fuel ρR.

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.

Two-dimensional focal plane counter with induction readout

Abstract A two-dimensional position sensitive gas proportional counter was constructed as a focal plane counter for a spectrograph with large dispersion. Position information along the focal plane is obtained by the charge division method using induced signals on resistive electrodes placed near the anodes. The vertical incidence position of a particle is determined from the drift time measurement. The usual deterioration of position resolution for non-normal incidence of the lightly ionizing particles is minimized by using a multi-anode design. The “induction readout” makes it possible to realize fast rise time of position pulses as well as of timing signals for the drift time measurement even for a 1.5 m long counter of multi-anode design.

Systematic observation of fine structure of the hole-state analogues in Ni isotopes

Abstract Using (p, d) reactions, fine structure of the ground hole-state anlogues in 57, 61, 63 Ni has been investigated with a magnetic spectrograph. The systematic variation of the spectra, including the 59 Ni data in our previous measurement, is interpreted in terms of isospin mixing. It is inferred that the most important contribution to the spreading width comes from the isovector monopole state in these nuclei.

Development of an 18 GHz superconducting electron cyclotron resonance ion source at RCNP

An 18 GHz superconducting electron cyclotron resonance ion source has recently been developed and installed in order to extend the variety and the intensity of ions at the RCNP coupled cyclotron facility. Production of several ions such as O, N, Ar, Kr, etc., is now under development and some of them have already been used for user experiments. For example, highly charged heavy ion beams like (86)Kr(21+,23+) and intense (16)O(5+,6+) and (15)N(6+) ion beams have been provided for experiments. The metal ion from volatile compounds method for boron ions has been developed as well.

The QDMDQ magnetic spectrograph “RAIDEN” (II) Correction of kinematic line broadening

Abstract Kinematic line broadening of the image was corrected by using multipole magnetic fields for the spectrograph “RAIDEN” at the Research Center for Nuclear Physics (RCNP). Arrival positions of the collimated rays with various angles of incidence were measured at the focal line as a function of strengths of the multipole magnetic fields. Measurements were performed for various values of the kinematic factor of nuclear particles scattered from the target nucleus. Strengths of the multipole fields which achieved the best directional focussing were extracted from the measured results. The strengths were proportional to the kinematic factor and the kinematic line broadening was corrected up to higher order in the median plane.