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Journal Articles

Influence of linear energy transfer on the scintillation decay behavior in a lithium glass scintillator

Koshimizu, Masanori*; Iwamatsu, Kazuhiro*; Taguchi, Mitsumasa; Kurashima, Satoshi; Kimura, Atsushi; Yanagida, Takayuki*; Fujimoto, Yutaka*; Watanabe, Kenichi*; Asai, Keisuke*

Journal of Luminescence, 169(Part B), p.678 - 681, 2016/01

We analyzed the effects of linear energy transfer (LET) on the scintillation properties of a Li glass scintillator, GS20. The scintillation time profiles were measured by using pulsed ion beams having different LETs. The rise in the scintillation time profiles was faster for higher LET, whereas the decay part was not significantly different for largely different LETs. The LET effects in the rise was ascribed to the effects of excited states interaction during the energy transfer process from the host glass to the luminescent centers, Ce$$^{3+}$$ ions. Supposing that the light yield decreases with LET, the fast rise at high LET was explained in terms of the competition between the energy transfer and the quenching due to the excited states interaction.

Journal Articles

Linear energy transfer effects on time profiles of scintillation of Ce-doped LiCaAlF$$_{6}$$ crystals

Yanagida, Takayuki*; Koshimizu, Masanori*; Kurashima, Satoshi; Iwamatsu, Kazuhiro*; Kimura, Atsushi; Taguchi, Mitsumasa; Fujimoto, Yutaka*; Asai, Keisuke*

Nuclear Instruments and Methods in Physics Research B, 365(Part B), p.529 - 532, 2015/12

 Times Cited Count:9 Percentile:69.75(Instruments & Instrumentation)

We measured temporal profiles of scintillation of Ce-doped LiCaAlF$$_{6}$$ scintillator crystals at different linear energy transfers (LETs). Based on the comparison of the high-LET temporal profiles with those at low LET, we found that a fast component was observed only at low LET. The disappearance of the fast component at high LET is tentatively ascribed to quenching of excited states at defects owing to the interaction between excited states via Auger process. In addition, the rise and the initial decay behavior was dependent on the LET. This LET-dependent behavior is explained by a seeming acceleration process and a slowing down process in energy transfer at high LET. The LET-dependent temporal profiles provide a basis of discrimination technique of $$gamma$$-ray and neutron detection events using these scintillators based on the nuclear reaction, $$^{6}$$Li(n,$$alpha$$)t.

Journal Articles

Pulse beam formation technique for a cyclotron

Kurashima, Satoshi

Hoshasen Kagaku (Internet), (100), p.49 - 51, 2015/10

no abstracts in English

Journal Articles

Evaluation of beam phase restriction with beam phase defining slit in the JAEA AVF cyclotron

Miyawaki, Nobumasa; Fukuda, Mitsuhiro*; Kurashima, Satoshi; Kashiwagi, Hirotsugu; Okumura, Susumu

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.706 - 708, 2015/09

no abstracts in English

Journal Articles

Preliminary test of injection tuning using an emittance and acceptance measurement system at the JAEA AVF cyclotron

Kashiwagi, Hirotsugu; Miyawaki, Nobumasa; Kurashima, Satoshi; Okumura, Susumu

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.703 - 705, 2015/09

no abstracts in English

Journal Articles

Present status of TIARA at JAEA

Yuyama, Takahiro; Ishibori, Ikuo; Kurashima, Satoshi; Yoshida, Kenichi; Ishizaka, Tomohisa; Chiba, Atsuya; Yamada, Keisuke; Yokoyama, Akihito; Usui, Aya; Miyawaki, Nobumasa; et al.

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.302 - 304, 2015/09

no abstracts in English

Journal Articles

Enhancement of beam pulse controllability for a single-pulse formation system of a cyclotron

Kurashima, Satoshi; Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Okumura, Susumu; Taguchi, Mitsumasa; Fukuda, Mitsuhiro*

Review of Scientific Instruments, 86(7), p.073311_1 - 073311_8, 2015/07

 Times Cited Count:10 Percentile:50.74(Instruments & Instrumentation)

The single-pulse formation technique using a beam chopping system consisting of two types of high-voltage beam kickers was modified to improve the quality and intensity of the single-pulse beam with pulse intervals over 1 $$mu$$s at TIARA cyclotron facility of Japan Atomic Energy Agency. Reduction of the multi-turn extraction number for suppressing the neighboring beam bunch contamination was achieved by restriction of a beam phase width and precise optimization of a particle acceleration phase. In addition, the single-pulse beam intensity was increased by a factor of two or more by a combination of two types of beam bunchers using sinusoidal and saw-tooth voltage waveforms. As a result, a contamination rate of neighboring beam bunches in the single-pulse beam was reduced to less than 0.1 %. Long-term purification of the single pulse beam was guaranteed by the well-controlled magnetic field stabilization system for the TIARA cyclotron magnet. Provision of the high quality intense single-pulse beam contributes to improve the accuracy of experiments for investigation of scintillation light time-profile and for neutron energy measurement by a time-of-flight method.

Journal Articles

System for measuring temporal profiles of scintillation at high and different linear energy transfers by using pulsed ion beams

Koshimizu, Masanori*; Kurashima, Satoshi; Taguchi, Mitsumasa; Iwamatsu, Kazuhiro; Kimura, Atsushi; Asai, Keisuke*

Review of Scientific Instruments, 86(1), p.013101_1 - 013101_5, 2015/01

 Times Cited Count:9 Percentile:47.26(Instruments & Instrumentation)

We have developed a system for measuring the temporal profiles of scintillation at high linear energy transfer (LET) by using pulsed ion beams from a cyclotron. The half width at half maximum time resolution was estimated to be 1.5-2.2 ns, which we attributed mainly to the duration of the pulsed ion beam and timing jitter between the trigger signal and the arrival of the ion pulse. The temporal profiles of scintillation of BaF$$_{2}$$ at different LETs were successfully observed. These results indicate that the proposed system is a powerful tool for analyzing the LET effects in temporal profiles of scintillation.

Journal Articles

Evaluation of phase bunching in the central region of a cyclotron by a radial probe with a plastic scintillator

Miyawaki, Nobumasa; Fukuda, Mitsuhiro*; Kurashima, Satoshi; Kashiwagi, Hirotsugu; Okumura, Susumu; Arakawa, Kazuo*; Kamiya, Tomihiro

Nuclear Instruments and Methods in Physics Research A, 767, p.372 - 378, 2014/12

 Times Cited Count:3 Percentile:30.04(Instruments & Instrumentation)

Journal Articles

Time resolution of beam phase distribution measurement system for the JAEA AVF cyclotron

Miyawaki, Nobumasa; Fukuda, Mitsuhiro*; Kurashima, Satoshi; Kashiwagi, Hirotsugu; Okumura, Susumu; Arakawa, Kazuo*; Kamiya, Tomihiro

Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1179 - 1181, 2014/10

no abstracts in English

Journal Articles

Effective emittance expansion for transverse acceptance measurement of an AVF cyclotron

Kashiwagi, Hirotsugu; Miyawaki, Nobumasa; Kurashima, Satoshi; Okumura, Susumu

Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1186 - 1188, 2014/10

no abstracts in English

JAEA Reports

Development of microbeam formation and single-ion hit technologies at the TIARA cyclotron

Yokota, Wataru; Sato, Takahiro; Kamiya, Tomihiro; Okumura, Susumu; Kurashima, Satoshi; Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Yoshida, Kenichi; Funayama, Tomoo; Sakashita, Tetsuya; et al.

JAEA-Technology 2014-018, 103 Pages, 2014/09

JAEA-Technology-2014-018.pdf:123.66MB

The world's first microbeam focusing technology for heavy ions of hundreds MeV accelerated by a cyclotron has been developed at the TIARA facility in the Takasaki Advanced Radiation Research Institute of the Japan Atomic Energy Agency. The technology enables us to form a microbeam of less than 1 $$mu$$m in diameter and to shoot a specified point on a target by one ion (single-ion hit) with spatial accuracy of microbeam size. In the course of the development, a cyclotron technology to accelerate a small energy-spread beam of hundres MeV, which is necessary for focusing to 1 $$mu$$m, has been developed as well as a beam focusing apparatus, beam size measurement and so forth based on the several-MeV microbeam/single-ion hit system of the TIARA electrostatic accelerators. Applicability of the technologies was examined by actual use in irradiation experiment and the result were fed back to them. This paper reports the process and the results of the development over ten years.

Journal Articles

Development of pulse beam formation technique for the JAEA AVF cyclotron

Kurashima, Satoshi; Miyawaki, Nobumasa; Okumura, Susumu

Hoshasen, 40(2), p.99 - 103, 2014/06

no abstracts in English

Journal Articles

Analysis of phase bunching in a central region of a cyclotron

Miyawaki, Nobumasa; Fukuda, Mitsuhiro*; Kurashima, Satoshi; Kashiwagi, Hirotsugu; Okumura, Susumu; Arakawa, Kazuo*; Kamiya, Tomihiro

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.500 - 502, 2014/06

no abstracts in English

Journal Articles

Analysis of phase bunching in AVF cyclotron

Miyawaki, Nobumasa; Kurashima, Satoshi; Kashiwagi, Hirotsugu; Okumura, Susumu; Yoshida, Kenichi; Yuri, Yosuke; Yuyama, Takahiro; Ishizaka, Tomohisa; Ishibori, Ikuo; Nara, Takayuki

JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 158, 2014/03

Journal Articles

Fast single-ion hit system for heavy-ion microbeam at TIARA cyclotron, 6

Yokota, Wataru; Sato, Takahiro; Okumura, Susumu; Kurashima, Satoshi; Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Yoshida, Kenichi; Koka, Masashi; Yokoyama, Akihito; Kada, Wataru*; et al.

JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 160, 2014/03

no abstracts in English

Journal Articles

Analysis of phase bunching in the central region of the JAEA AVF cyclotron

Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Kurashima, Satoshi; Okumura, Susumu; Fukuda, Mitsuhiro*

Proceedings of 20th International Conference on Cyclotrons and their Applications (CYCLOTRONS 2013) (Internet), p.350 - 352, 2014/03

Journal Articles

A Transverse emittance and acceptance measurement system in a low-energy beam transport line

Kashiwagi, Hirotsugu; Miyawaki, Nobumasa; Kurashima, Satoshi; Okumura, Susumu

Review of Scientific Instruments, 85(2), p.02A735_1 - 02A735_5, 2014/02

 Times Cited Count:2 Percentile:13.22(Instruments & Instrumentation)

Journal Articles

Influence of injection beam emittance on beam transmission efficiency in a cyclotron

Kurashima, Satoshi; Kashiwagi, Hirotsugu; Miyawaki, Nobumasa; Yoshida, Kenichi; Okumura, Susumu

Review of Scientific Instruments, 85(2), p.02A725_1 - 02A725_3, 2014/02

 Times Cited Count:0 Percentile:0.01(Instruments & Instrumentation)

The JAEA AVF cyclotron accelerates various kinds of high energy ion beams for research in biotechnology and materials science. Beam intensity of an ion species of the order of 10$$^{-9}$$ to 10$$^{-6}$$ ampere is often required for various experiments sequentially performed within a day. To provide the ion beam sufficiently and stably, an operator has to retune an ion source in a short time. The beam intensity downstream of the cyclotron, however in most cases, doesn't increase proportionally to the intensity at the ion source. To understand the cause of this beam behavior, transmission efficiencies of a $$^{12}$$C$$^{5+}$$ beam from the ion source through the cyclotron were measured for various conditions of the ECR ion source. Moreover, a feasible region for acceleration in the emittance of the injection beam was clarified using a transverse-acceptance measuring system. We confirmed that the beam emittance and profile changed depending on the condition of the ion source and the matching between the emittance and the acceptance of the cyclotron got worse. After fine-tuning to improve the matching, the beam intensity downstream of the cyclotron increased.

Journal Articles

Geometric analysis of phase bunching in the central region of cyclotron

Miyawaki, Nobumasa; Fukuda, Mitsuhiro*; Kurashima, Satoshi; Kashiwagi, Hirotsugu; Okumura, Susumu; Arakawa, Kazuo*; Kamiya, Tomihiro

Nuclear Instruments and Methods in Physics Research A, 715, p.126 - 131, 2013/07

 Times Cited Count:2 Percentile:21.46(Instruments & Instrumentation)

An optimum condition for realizing phase bunching in the central region of a cyclotron was quantitatively clarified by a simplified geometric trajectory analysis of charged particles from the first to the second acceleration gap. The phase-bunching performance was evaluated for a general case of a cyclotron. The phase difference of incident particles at the second acceleration gap depends on the combination of four parameters: the acceleration harmonic number ${it h}$, the span angle ${it $theta$$_{D}$}$ of the dee electrode, the span angle ${it $theta$$_{F}$}$ from the first to the second acceleration gap, the ratio ${it R$_{V}$}$ of the peak acceleration voltage between the cyclotron and ion source. Optimum values of ${it $theta$$_{F}$}$ for phase bunching were limited by the relationship between ${it h}$ and ${it $theta$$_{D}$}$, which is 90$$^{circ}$$/${it h}$+${it $theta$$_{D}$}$/2 $$leq$$ ${it $theta$$_{F}$}$ $$leq$$ 180$$^{circ}$$/${it h}$+${it $theta$$_{D}$}$/2, and sin${it $theta$$_{F}$}$ $$>$$ 0. The phase difference with respect to the reference particle at the second acceleration gap is minimized for voltage-ratios between two and four for an initial phase difference within 40 RF degrees. Although the slope of the first acceleration gap contributes to the RF phase at which the particles reach the second acceleration gap, phase bunching was not affected. An orbit simulation of the JAEA AVF cyclotron verifies the evaluation based on geometric analysis.

201 (Records 1-20 displayed on this page)