DESIGN STUDY OF MAGNETIC CHANNEL AT NIRS-AVF930

In the NIRS-AVF930 cyclotron, a current magnetic channel has been used for ten years, and the flow of cooling water gradually decreases. Therefore, the high energy operation such as 70 MeV proton became recently difficult. As the design specification of this magnetic channel is very severe, the flow velocity of cooling water is very fast as 5.4 m/sec. The condition of the current magnetic channel and the design consideration of a new one will be presented.19th International Conference on Cyclotrons and their Application

OBSERVATION OF LONGITUDINAL SPACE CHARGE EFFECTS IN THE INJECTION BEAM LINE OF NIRS-930 CYCLOTRON

International Particle Accelarator Conference 201

PRESENT STATUS OF CYCLOTRONS (NIRS-930, HM-18) AT NIRS

The cyclotron facility at National Institute of Radiological Science (NIRS) consists of a NIRS-930 cyclotron (Thomson-CSF AVF-930, Kb=110 MeV and Kf=90 MeV) and a small cyclotron HM-18(Sumitomo- Heavy- Industry HM-18, K=20 MeV). The NIRS-930 has been used for production of short-lived radio-pharmaceuticals for Positron Emission Tomography (PET), research of physics, developments of particle detectors in space, and so on. The orbit of a beam in the NIRS-930 cyclotron was simulated with integrated approach for modelling of the cyclotron, including calculation of electromagnetic fields of the structural elements. And some improvements such as installation of extracted beam probe, a beam attenuator and a beam viewer in an injection beam line, were performed in the NIRS-930. The HM-18 has been used for production of short-lived radio-pharmaceuticals for PET. It provides us accelerated H-and D- ions at fixed energies of 18 and 9 MeV, respectively. In order to improve the isochronisms, a phase probe has been newly installed in the HM-18. Operational status of the cyclotron facilities and their improvements are to be presented in this report.20th International Conference on Cyclotrons and their Application

Application of compact ECR ion source

Abstract: A gas-pulsing system for an Electron Cyclotron Resonance Ion Source with all permanent magnets (Kei2-source) at NIRS has been developed and tested. The system consists of a small vessel (30 ml) to reserve CH4-gas, and two fast solenoid valves that are installed at both sides of the vessel. They are connected to each other and to the Kei2-source by using a stainless-steel pipe (4 mm in inner-diameter), where the length of the pipe from the valve to the source is 60 cm and the conductance is 1.2 l/s.From the results of a test, almost 300 eA for a pulsed 12C4+ beam was obtained at a Faraday-cup in an extraction-beam channel with a pressure range of 4000 Pa in the vessel. At this time, the valve has an open time of 10 ms and the delay time between the valve-open and applying microwave power is 100 ms, respectively.In experiments, the conversion efficiency for input CH4 molecules to the quantity of extracted 12C4+ ions in one beam-pulse was found to be around 3%, and the ratio of the total amount of the gas requirement was only 10% compared with a case of continuous gas provided in 3.3 second of repetition in HIMAC.第12回イオン源国際会

Production of 11C-beam for particle therapy

A technical realization of a positron emitter 11C-beam (R.I.) as an accelerating beam has been studied at NIRS-HIMAC in order to apply it to heavy-ion therapy. The purpose of the present study is to show how to obtain a suitable beam intensity of a 11C-beam extracted from the HIMAC-synchrotron. Regarding this study, related developmentsinclude the production of radioactive isotopes (11C) by a cyclotron, gas-separation, gas-compression, gas-pulsing and ionization. Further, residue 11CO2-gas can be reproduced in the ionization process. As the result of a calculation, an order of 108 ppp of 11C6+ ions can be extracted from the HIMAC-synchrotron during 18 min at 3.3 s intervals with a 1 ms beam pulse under the assumption of 1 Ci of 11C-production. Details of the study are presented

Low-energy ion decelerator for an external injection line at the NIRS-930 cyclotron

A low-energy ion decelerator for the acceleration-deceleration system has been designed and installed in the beam-injection line of the NIRS-930 cyclotron in an attempt to increase the beam intensity from the cyclotron. With this acceleration-deceleration system, the beam intensity of C-12(4+) ions at the cyclotron exit has been increased by about five times. The system has an advantage in that it allows us to extract a high-current ion beam from an electron cyclotron resonance ion source because, independently of the injection-energy matching to the cyclotron, a large potential difference can be applied between the source and the extractor. The voltage applied to the extractor is about -12 kV, which is reduced to the ground potential by the decelerator. The electric field distributions in the deceleration system were carefully designed using a three-dimensional field simulator. Design studies of the decelerator as well as the result of a beam test are presented

Development of gas pulsing system for electron cyclotron resonance ion source

A gas-pulsing system for an electron cyclotron resonance ion source with all permanent magnets (Kei2 source) at NIRS has been developed and tested. The system consists of a small vessel (30 ml) to reserve CH4 gas and two fast solenoid valves that are installed at both sides of the vessel. They are connected to each other and to the Kei2 source by using a stainless-steel pipe (4 mm inner diameter), where the length of the pipe from the valve to the source is 60 cm and the conductance is 1.2 l / s. From the results of the test, almost 300 e microA for a pulsed 12C4+ beam was obtained at a Faraday cup in an extraction-beam channel with a pressure range of 4000 Pa in the vessel. At this time, the valve has an open time of 10 ms and the delay time between the valve open time and the application of microwave power is 100 ms. In experiments, the conversion efficiency for input CH4 molecules to the quantity of extracted 12C4+ ions in one beam pulse was found to be around 3% and the ratio of the total amount of the gas requirement was only 10% compared with the case of continuous gas provided in 3.3 s of repetition in HIMAC