Effect due to Cs injection upon current oscillation of the beam extracted from the J-PARC negative hydrogen ion source

Wada, Motoi*; Shibata, Takanori*; Shinto, Katsuhiro

Journal of Instrumentation (Internet), 19(2), p.C02019_1 - C02019_7, 2024/02

https://doi.org/10.1088/1748-0221/19/02/C02019

A negative hydrogen (H) ion source with the plasma excited by 2 MHz radio frequency (RF) power serves as the beam source for the Japan Proton Accelerator Research Complex (J-PARC). We have been studying the H ion beam intensity modulation at the frequency of plasma excitation RF power since we have found the beam carried the fluctuation at 2 MHz after the RFQ linac. Higher frequency components were found present in the peripheral region of the plasma, and the highspeed emittance measurement system developed to clarify the change of the beam in phase space revealed the existence of diverging halo component oscillating at 2 MHz. The fluctuation amplitude at the beam center was less than about 20%, while there was observed the component oscillating at 4 MHz. The 4 MHz component seems related to the production of high energy electrons by the RF antenna as the intensity of the RF induction electric field takes the maximum twice in each cycle. On the other hand, the direction of RF magnetic field and the direction of electron flow change at 2 MHz frequency. Thus, H ion formation mechanisms in the ion source can be estimated through precisely characterizing the extracted H ion beam. The H ion beam fluctuation can be observed in the H ion current measured with a Faraday cup. Before introducing Cs, the measured beam current showed the fluctuation at 4 MHz frequency when the axial magnetic field correction (AMFC) coil was turned off. The main fluctuation frequency changed to 2 MHz as the voltage to excite the coil to induce AMFC was increased. Injection of Cs into the ion source increased the H ion current, while the 4 MHz component nearly disappeared for both cases of AMFC on and AMFC off. Possible mechanisms responsible for diminishing 4 MHz fluctuation component by Cs injections are discussed.

120 mA operation of J-PARC cesiated RF-driven H ion source

Ueno, Akira; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Oguri, Hidetomo

Journal of Instrumentation (Internet), 18(8), p.C08002_1 - C08002_8, 2023/08

https://doi.org/10.1088/1748-0221/18/08/C08002

On 2020, the stable operation of the J-PARC cesiated RF-driven H ion source (IS) with a 65 keV 110 mA beam, whose emittances were suitable for the radio-frequency quadrupole LINAC, was reported. In the J-PARC IS operation, the stable plasma production with a 50 kW 2 MHz RF power for more than 3 months, an RF power efficiency higher than 2.6 mA/kW and the possibility of the space charge limited beam intensity pulling up by increasing the extraction and acceleration voltages (V and V) were proven. The stable operation results with a 69.9 keV 120 mA beam realized by increasing the withstand voltage around the 2 MHz RF matching circuit are presented. The 107.8 mA of the beam was measured inside the emittances used for the RFQ design.

Estimation of the effect of GNSS positioning errors on the dose rate calculation concerning aerial radiation monitoring

Mori, Airi; Seguchi, Eisaku*; Futemma, Akira; Iwai, Takeyuki*; Sanada, Yukihisa

Journal of Instrumentation (Internet), 17(10), p.P10015_1 - P10015_11, 2022/10

https://doi.org/10.1088/1748-0221/17/10/P10015

Performance of RHICf detector during operation in 2017

Adriani, O.*; Tanida, Kiyoshi; RHICf Collaboration*; 17 of others*

Journal of Instrumentation (Internet), 16(10), p.P10027_1 - P10027_16, 2021/10

https://doi.org/10.1088/1748-0221/16/10/P10027

Measurements of intensity of produced light in water during irradiations of electron beams with energies above and below the Cerenkov-light threshold

Yamamoto, Seiichi*; Nagao, Yuto*; Kurita, Keisuke; Yamaguchi, Mitsutaka*; Kawachi, Naoki*

Journal of Instrumentation (Internet), 16(1), p.P01007_1 - P01007_9, 2021/01

https://doi.org/10.1088/1748-0221/16/01/P01007

Luminescence of water during irradiation with particles having energies below the Cerenkov-light threshold was recently found for various types of radiations. However, the relation between the intensities of Cerenkov light and of the luminescence of water at the beam energy below the Cherenkov threshold is not well known. To clarify this point, we measured the produced light irradiating a water sample with electron beams having maximum energies above and below the Cerenkov-light threshold.

J-PARC 3-GeV RCS; 1-MW beam operation and beyond

Hotchi, Hideaki; Harada, Hiroyuki; Hayashi, Naoki; Kinsho, Michikazu; Okabe, Kota; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Yamamoto, Kazami; Yamamoto, Masanobu; et al.

Journal of Instrumentation (Internet), 15(7), p.P07022_1 - P07022_16, 2020/07

https://doi.org/10.1088/1748-0221/15/07/P07022

no abstracts in English

A Three-dimensional radiation image display on a real space image created via photogrammetry

Sato, Yuki; Ozawa, Shingo*; Tanifuji, Yuta; Torii, Tatsuo

Journal of Instrumentation (Internet), 13(3), p.P03001_1 - P03001_8, 2018/03

https://doi.org/10.1088/1748-0221/13/03/P03001

Development of a bump cathode element for two-dimensional neutron detection

To, Kentaro; Nakamura, Tatsuya; Sakasai, Kaoru; Yamagishi, Hideshi*

Journal of Instrumentation (Internet), 12(12), p.C12011_1 - C12011_8, 2017/12

https://doi.org/10.1088/1748-0221/12/12/C12011

A neutron-detection element using circular cathode bumps was developed for two-dimensional neutron measurement, and an irradiation experiment was performed using a Cf neutron source. The element has triangularly arranged small-sized circular cathode bumps, and the bumps are linked together in the x- and y-directions for the detection of incident neutrons. The element was arranged in the pressure vessel with a fill gas of composition He/(15%)CF at 0.7 MPa. The detector system using bump cathode element exhibited a two-dimensional uniformity with a response of 10.1%. The average intrinsic spatial resolution was 1.89 mm full width at half maximum in the sensitive region, calculated by taking into account the track lengths of the secondary particles.

EXILL; A High-efficiency, high-resolution setup for -spectroscopy at an intense cold neutron beam facility

Jentschel, M.*; Blanc, A.*; de France, G.*; Kster, U.*; Leoni, S.*; Mutti, P.*; Simpson, G.*; Soldner, T.*; Ur, C.*; Urban, W.*; et al.

Journal of Instrumentation (Internet), 12(11), p.P11003_1 - P11003_33, 2017/11

https://doi.org/10.1088/1748-0221/12/11/P11003

Development of CdTe pixel detectors combined with an aluminum Schottky diode sensor and photon-counting ASICs

Toyokawa, Hidenori*; Saji, Choji*; Kawase, Morihiro*; Wu, S.*; Hurukawa, Yukihito*; Kajiwara, Kentaro*; Sato, Masugu*; Hirono, Toko*; Shiro, Ayumi*; Shobu, Takahisa; et al.

Journal of Instrumentation (Internet), 12(1), p.C01044_1 - C01044_7, 2017/01

https://doi.org/10.1088/1748-0221/12/01/C01044

We have been developing CdTe pixel detectors combined with a Schottky diode sensor and photon-counting ASICs. The hybrid pixel detector was designed with a pixel size of 200 micro-meter by 200 micro-meter and an area of 19 mm by 20 mm or 38.2 mm by 40.2 mm. The photon-counting ASIC, SP8-04F10K, has a preamplifier, a shaper, 3-level window-type discriminators and a 24-bits counter in each pixel. The single-chip detector with 100 by 95 pixels successfully operated with a photon-counting mode selecting X-ray energy with the window comparator and stable operation was realized at 20C. We have performed a feasibility study for a white X-ray microbeam experiment. Laue diffraction patterns were measured during the scan of the irradiated position in a silicon steel sample. The grain boundaries were identified by using the differentials between adjacent images at each position.