Katsunori Kawasaki

Development of thick, long-lived carbon stripper foils for PSR of LANL

Abstract Thick carbon stripper foils (multi-layer thickness ≈ 200 μg/cm 2 ) have been developed for use with 800 MeV, H + ion beam in the Proton Storage Ring (PSR) at Los Alamos National Laboratory. Foils were prepared by means of the modified controlled ACDC arc discharge method (mCADAD). The lifetime measurements of the foils made by different methods were performed using an 800 MeV proton beam of up to 85 μA in the PSR, and a 3.2 MeV Ne + ion beam of 3 μA at Tokyo Institute of Technology. The foils made by the mCADAD method showed very long lifetimes, as compared to other foils tested, for both 800 MeV p and 3.2 MeV Ne + beam bombardments.

Development of heavy ion beam sputtering method for long-lived carbon stripper foils

Abstract A heavy noble gas ion beam sputtering (HIBS) technique was developed to prepare carbon stripper foils with a characteristic of long lifetime. The dependence of lifetimes on the mass of noble gas was also investigated. Compared with foils made by lighter ions such as Ne and Ar, the foils made by Kr and Xe noble gases were not so much stronger mechanically, but were long-lived under bombardment with a 3.2 MeV Ne+ ion beam 3 μA in intensity and 3.5 mm in diameter. The mean lifetime in the case of Kr sputtering gas was around 51 mC, 20 times longer than that of commercially available foils. The key point in producing long-lived foils with Kr or Xe noble gas ions was found to be to decrease the amount of oxygen contaminants as much as possible.

Nitrided carbon foils as long-lived charge strippers

Abstract Nitrided carbon stripper foils with excellent lifetimes and mechanical properties have been made by a new method based on reactive nitrogen-ion-beam sputtering. The foils showed no shrinkage and maintained mechanical flexibility during long periods of irradiation by ion beams. The average integrated current stripped by such foils before breakage was 75 mC using a 3.2 MeV Ne+ beam flux of 4 μA, 3.5 mm in diameter. This capability is about 30 times greater than commercially available carbon stripper foils. Details are given for the method of preparation and the compositions of the foils produced.

CARBON STRIPPER FOIL PREPARATION BY ION BEAM SPUTTERING WITH 3.5 KEV KR IONS

Abstract Heavy ion-beam sputtering with low beam voltage was found to be applicable for the preparation of long-lived carbon stripper foils. A test foil (25 μg/cm 2 ) made by this method survived an integrated ion current of 6213 mC/cm 2 corresponding a lifetime of about 200 times the best commercially available foil made by evaporation-condensation. The present method can be expected to be applicable to magnetron sputtering for mass production of carbon stripper foils.

Behaviour of carbon stripper foils prepared by a mixed ion beam sputtering method

Abstract Carbon stripper foils have been prepared by a mixed ion beam sputtering method and the lifetime measured by using 3.2 MeV Ne+ ions. Foils prepared by the mixed ion beam sputtering method have lifetimes ranging from 10 to 125 times longer than those produced by thermal evaporation method. Changes in foil thickness with increasing fluence were examined. The lifetime and sputtering ratio of the carbon foils were found to be strongly dependent on thickness.

Compact IH-APF type linac for PIXE and RBS analyses

We studied an IH-APF type linac for PIXE and RBS analyses use. The compact (La 1.5 m) linac accelerates protons from 40 keV to 2.0 MeV. This alternating-phase-focus (APF) system cannot focus such a high intense beam, but a beam of several 100 lA is focused by the combination of Focus‐Defocus sequence. For PIXE and RBS analyses, intensity of bombard particles is several lA lower than several 100 lA. From particle orbit calculation, on energy width of a0.2%, this linac can accept transverse emittance of 113 pmm mrad, longitudinal phase of 35∞ (by using two bunchers, beam transmission gets larger than 80%) and beam intensity of several 100 lA. The linac can accelerate protons to 2.0 MeV by RF power of about 10 kW. We designed the interdigital H (IH) linear accelerator by particle-orbit calculation. All PIXE and RBS analyses systems occupy only 2 m · 3 m. A half-model cavity was designed. The model is being manufactured now for measurement of RF characteristics. ” 2000 Elsevier Science B.V. All rights reserved.

Evaluation of the Pollution by Toxic Elements around the Small-Scale Mining Area, Boroo, Mongolia

The objective of this study is to investigate the contamination levels of toxic elements (TEs) in the vicinity of the small-scale mining Boroo area, Mongolia. Samples of surface soil, ground water and human hair were collected around the gold washing or milling places, grassland and village areas. After appropriate preparation, all samples were analyzed for major and toxic elements (TEs) by Particle-Induced X-ray Emission Spectrometry (PIXE). Soil texture, conductivity (EC), pH, total organic carbon (TC) and nitrogen (TN) contents were also measured. The enrichment factor (EF) was estimated to assess the level of the contamination and the possible anthropogenic impact in soils from the mining activity. The EFsoil for Cu, As and Pb were in the highest values around gold washing place, indicating that around mining area surface soils were highly enriched by those elements. The Mn, Fe and Ni concentrations of drinking waters exceed the WHO values. The mean concentrations of Ca, Ti, As and Sr were higher in hair of Mongolian miners than in the hair of normal people in Japan, Mongolia and Philippines. These results indicate that the area around gold washing or milling could be the main contamination sources of As and other toxic elements (TEs) in the surface soil samples.

Fabrication of Boron-Mixed Carbon Stripper and Target Backing Foils for High-Power Accelerators

We have succeeded, for the first time, in making long-lifetime boron-mixed carbon stripper foils for high-power accelerators. Foils of 10–1000 µg/cm2 thickness were made by controlled DC arc discharge. The lifetime of the foils was tested using 3.2 MeV Ne+ DC beams of 2.5 µA, by which a significant amount of energy was deposited in the foils. The maximum lifetime was found to be extremely long, 110 and 450 times longer than those of diamond and commercially available carbon foils, respectively. The foils turned out to be free from any shrinkage, and showed an extremely low thickness reduction rate, even at a high temperature of 1800 K.

Construction of 1.7 MV Pelletron Tandem Accelerator System and Its Application to Human Resource Development at Tokyo City University Atomic Energy Research Laboratory

Naoto HAGURA, Noriyosu HAYASHIZAKI, Takafumi UCHIYAMA, Yoshiyuki OGURI, Hitoshi FUKUDA, Katsunori KAWASAKI, Tamotsu TORIYAMA, Koichi MOCHIKI, Yukiko OKADA, Jun KAWARABAYASHI, Ishi MITSUHASHI and Haruaki MATSUURA 1 Department of Nuclear Safety Engineering, Tokyo City University, 1-28-1 Tamazutsumi, Setagaya-ku, Tokyo 158-8557, Japan 2 Atomic Energy Research Laboratory, Tokyo City University, 971 Ozenji, Asao-ku, Kawasaki, 215-0013, Japan 3 Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan 4 Technical Department, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan 5 Electrostatic Accelerator Research Laboratory, 3-1-22-P2-502 Honcho, Higashikurume-city, Tokyo 203-0053, Japan 6 Laboratory for Materials Engineering with Quantum Beams, 4-2-17 Nishigahara, Kita-ku, Tokyo 114-0024, Japan

High power acceleration of an HSC type injector for cancer therapy

A hybrid single cavity（HSC） linac, which is formed by combining a radio frequency quadrupole（RFQ）and a drift tube（DT） structure into one interdigital-H（IH） cavity, is fabricated and assembled as a proof of principle injector for cancer therapy synchrotron, based on the culmination of several years of research. The HSC linac adopts a direct plasma injection scheme（DPIS）, which can inject a high intensity heavy ion beam produced by a laser ion source（LIS）. The input beam current of the HSC is designed to be 20 m A C6+ ions. According to numerical simulations, the HSC linac can accelerate a 6-m AC6+ beam, which meets the requirement of the needed particle number for cancer therapy（108-9ions/pulse）. The HSC injector with the DPIS method makes the existing multiturn injection system and stripping system unnecessary, and can also bring down the size of the beam pipe in existing synchrotron magnets, which could reduce the whole cost of synchrotron. The radio frequency（rf） measurements show excellent rf properties for the resonator, with a measured Q equal to 91% of the simulated value. AC6+ ion beam extracted from the LIS was used for the HSC commissioning. In beam testing, we found the measured beam parameters agreed with simulations. More details of the measurements and the results of the high power test are reported in this paper.A hybrid single cavity (HSC) linac, which is formed by combining a radio frequency quadrupole (RFQ) and a drift tube (DT) structure into one interdigital-H (IH) cavity, is fabricated and assembled as a proof of principle injector for cancer therapy synchrotron, based on the culmination of several years of research. The HSC linac adopts a direct plasma injection scheme (DPIS), which can inject a high intensity heavy ion beam produced by a laser ion source (LIS). The input beam current of the HSC is designed to be 20 mA C6+ ions. According to numerical simulations, the HSC linac can accelerate a 6-mA C6+beam, which meets the requirement of the needed particle number for cancer therapy (108–9 ions/pulse). The HSC injector with the DPIS method makes the existing multi-turn injection system and stripping system unnecessary, and can also bring down the size of the beam pipe in existing synchrotron magnets, which could reduce the whole cost of synchrotron. The radio frequency (rf) measurements show excellent rf properties for the resonator, with a measured Q equal to 91% of the simulated value. A C6+ ion beam extracted from the LIS was used for the HSC commissioning. In beam testing, we found the measured beam parameters agreed with simulations. More details of the measurements and the results of the high power test are reported in this paper.