| Project/Area Number |
17540274
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Particle/Nuclear/Cosmic ray/Astro physics
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| Research Institution | Nagasaki Institute of Applied Science |
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Principal Investigator |
KIMURA Kikuo Nagasaki Institute of Applied Science, Engineering, Part-time Instructor, 工学部, 非常動講師 (60108636)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2006: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2005: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Keywords | counter telescope / high-energy heavy ion / particle identification / ΔE counter / time of flight measurement / gas ionization chamber / plastic scintillator / プラスチックシンチレータ / NaI検出器 / 飛行時間側定 |
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| Research Abstract |
A counter telescope composed of three different types of detectors was developed using a tilted electrode gas ionization chamber as a ΔE-counter, an NaI(Tl) detector as an energy counter and a plastic scintillator as a TOF counter. Among them a combination of the A E-counter and the NaI(Tl) detector was first tested for identifying atomic numbers of high-energy heavy ions at the HIMAC accelerator of the National Institute of Radiological Sciences. Heavy ion beams of Kr(Z=36) and Xe(Z=54) with energies up to 400MeV/N, which is close to the energy region of the RI beam factory, were used. It was found that the identification of atomic numbers was quite good for heavy ions up to Z=54. But the quality of the NaI(Tl) detector was limited to the region of low beam intensity around 100 particles/spill. At the higher beam intensities, output pulse heights of the NaI(Tl) detector decreased with increasing beam intensities and the linear relation between beam energy and pulse height was distorted. Such distortion renders deterioration of mass resolution when the NaI(Tl) detector together with a TOF counter was used to identify mass numbers. Thus it remains necessary to develop a high-rate energy counter.
As for a plastic scintillator used as a TOF counter, time resolution was tested by reading light outputs from four sides of the square scintillator using fast photomultiplier tubes. Arrival times of light to the four phototubes were determined not using electronic circuits, like constant fraction discriminators, but by analyzing waveforms of the phototube signals measured by a 4-channel digital storage scope. By this analysis, we could reduce the effect of noise on the waveform data. In a test experiment using cosmic rays, we obtained the time resolution of 90 ps. For heavy ions which yield much larger light outputs than cosmic rays, a timing resolution of much better than 90 ps is expected.
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