Minoru Imamura

Light output response of LYSO(Ce) crystal to relativistic helium and carbon ions

The light output response of LYSO(Ce) crystals was investigated using helium and carbon beams of 720 MeV and 3.48 GeV, respectively. Experimental results showed good agreement with the calculated curves by the Birks equation but the values of the parameters in the equation were different between helium and carbon ions.

Light Output Response of GSO(Ce) Crystals to Relativistic Carbon Ions

We have investigated the light output response of a GSO(Ce) crystal to carbon ions of energy up to 3.34 GeV. An experiment was carried out with HIMAC at National Institute of Radiological Sciences in Chiba, Japan. The incident energy of carbon beam was changed by inserting target materials with different thicknesses as degraders. Experimental results were consistent with the calculated curve by Birks equation, and the light output plotted as a function of deposited energy in the GSO(Ce) crystal showed a slight non-linearity in the low energy region and a good linearity in the higher energy region above around 1.5 GeV.

Development of Gas Proportional Scintillation Counter for Light Heavy‐Ion Detection

In recent years, nuclear data have been needed in the medical field. Nuclear data induced by light heavy ions are especially needed at high precision for cancer treatment, although there are not enough usable data at present.We have a plan to measure light heavy‐ion nuclear data with a dE‐E detector. Low density is needed for the dE detector. We have two options for the dE detector: a semiconductor detector (SSD) and a Gas Counter. On one hand, SSD has good energy resolution, but on the other hand, it is expensive and its decay time is on the 100‐microsecond order. A Gas Counter is inexpensive, and a Gas Proportional Scintillation Counter (GPSC) has fast decay time. Then, we developed a GPSC for the dE detector, and its evaluation experiment was carried out at the Heavy Ion Medical Accelerator in Chiba (HIMAC).We will report the results of the experiment with the performance of the GPSC.

A new detector system for the measurement of double differential cross sections of proton-actinide reactions in the 600-MeV region

A new detector system was proposed for the measurement of the double differential cross section (DDX) data on proton-actinide reactions in the 600-MeV region. The detector system is the combination of pulse height measurement and TOF measurement. In the pulse height measurement, conventional ΔE-E method was used with a plastic scintillator and an inorganic crystal. The TOF measurement was done by using two plastic scintillators. The result of the preliminary experiment carried out using 230 MeV/u helium beam is reported.

Magnetic Fluid Behavior under External Fields in View of Medical Applications

Characteristic behavior of magnetic fluid was investigated for a key technology study of the magnetic targeting drug delivery system, which is the specific delivery of chemotherapeutic agents to a desired location in the body, such as tumor by the control of an external magnetic field. Transparent images of the fluid were taken by using a CCD camera and an intense X-ray beam at the SPring-8. The reduction of the image information has lead to clarify the distribution of nanoparticles inside the fluid as a function of external field strength. The physical interactions between nanoparticles, one of the essential factors to achieve the drug delivery control, were discussed.

Proton Production Cross Sections for Reactions Induced by 300‐ and 392‐MeV Protons

Multistep direct processes in proton production reactions were investigated with proton beam of 300‐ and 392‐MeV bombarding targets nuclei. The targets nuclei are 181Ta, 197Au, and 209Bi for 392 MeV and 197Au for 300 MeV protons. Energy spectra were measured at several laboratory angles from 20° to 105° and compared with two theoretical models, the quantum molecular dynamics and the intranuclear cascade model. At intermediate energy, the double differential cross section is sensitive to ground state in codes. We found that a more realistic ground state led better accounting of measured data.