IPAC2016 - List of Authors (Kuboki, H.)

Paper	Title	Page
MOPMB024	Electron Cloud Measurements at J-PARC Main Ring	137
	B. Yee-Rendón, H. Kuboki, R. Muto, K. Satou, M. Tomizawa, T. Toyama, M. Uota KEK, Ibaraki, Japan
	Electron cloud instability is presented in most of the high intensity proton rings. During the Slow beam extraction (SX) mode at Main Ring of J-PARC, signals related with its formation were observed. An electron cloud detector is installed downstream of the ElectroStatic Septum (ESS), to measure the electron signal. Additionally, scintillation detector with photomultiplier, a proportional counter and photo-diode were set closely to the electron cloud detector to observe the beam lost. This paper presents the measurements of the electron cloud and some of the conditions which support its creation, for instance the signal of lost particle from the beam loss monitors, the residual gas in the vacuum duct by using vacuum pressure gauges, etc.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB024
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MOPMB025	The Development of 16-Electrode Monitor for Measurement of the Multipole-Moment	140
	Y. Nakanishi, A. Ichikawa, A. Minamino, K.G. Nakamura, T. Nakaya Kyoto University, Kyoto, Japan T. Koseki, H. Kuboki KEK, Tokai, Ibaraki, Japan T. Toyama J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	Funding: This work was supported by MEXT KAKENHI Grant Number 25105002, Grant-in-Aid for Scientific Research on Innovative Areas titled 'Unification and　Development of the Neutrino Science Frontier' In the J-PARC main ring, the beam intensity is greatly increased to 750 kW or more in near future. Even the beam intensity become higher, the beam loss must be kept at the same level as present. Aiming to make the cause of beam loss clear, we have been developing the beam monitor to measure the beam size. The quadrupole moment is related to the beam size. In principle, monitors with more than four electrodes can measure the quadrupole moment. In addition, two monitors located at the places with different beta functions can measure the emittances and beam sizes, providing the horizontal and vertical beta functions. To obtain more precise quadrupole moment and higher multipoles, we are developing the multi-electrode monitor, tentatively, with 16 electrodes. As a reference of 16-electrode monitor, two 4-electrode BPMs are investigated to measure quadrupole moments. We will present the measurement result of 4-electrode monitors and the status of the development of the 32-electrode monitor.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB025
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WEPOR021	Residual Radiation Monitoring by Beam Loss Monitors at the J-PARC Main Ring	2715
	T. Toyama, K. Satou J-PARC, KEK & JAEA, Ibaraki-ken, Japan H. Kuboki, H. Nakamura, B. Yee-Rendón KEK, Ibaraki, Japan M.J. Shirakata JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	At J-PARC (the Japan Proton Accelerator Research Complex), high intensity proton accelerator, controlling and localizing beam losses and residual radiations are key issue, because the residual radiation limits maintenance work in efficiency and working hours, and then limits machine availability. We are accumulating continuous measurement data of residual radiation after beam stop using beam loss monitors in the Main Ring (MR). The wire cylinder gaseous radiation detectors are used in a proportional counting region. The heads are DC-connected and have a gain as large as 30000 with a bias of -2 kV. We switch the DAQ trigger from "Beam Trigger" to "No Beam Trigger", change the ADC sampling rate to 16 ms, and raise the gain by changing the bias voltage from -1.6 kV to -2.0 kV with a few exceptions when the accelerator operation ends. The offsets are measured with zero bias voltage. Identification of radionuclides has been performed with time decay analysis, with assistance of energy spectrum measurements with the Gamma Ray Spectrometer, Kromek GR1-Spectro.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR021
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THPOY034	Simulations of the Beam Loss Distribution at J-PARC Main Ring	4175
	B. Yee-Rendón, H. Kuboki, Y. Sato, K. Satou, M.J. Shirakata, T. Toyama KEK, Ibaraki, Japan H. Harada JAEA/J-PARC, Tokai-mura, Japan
	The Japan Proton Accelerator Research Complex (J-PARC) is integrated by a set of high intensity proton accelerators. At this operation level, the monitoring and control of the beam losses and residual radiation are priority for its safe performance and maintenance. At Main Ring (MR), a discrepancy appears between the beam loss signal detected by the monitors and the residual dose measured. To understand this difference and the mechanism that produces these losses, a beam simulation study is implemented using the Strategic Accelerator Design (SAD) and Geometry and Tracking (Geant4) code. The first stage of the survey uses SAD to obtain the location of the losses around the lattice per turn. Then, Geant4 produces the secondary showers in the elements. Finally, we make the extrapolation with the residual radiation and compare with the measurements. The description and results of this work are presented in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY034
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Paper

Title

Page

Electron Cloud Measurements at J-PARC Main Ring

137

B. Yee-Rendón, H. Kuboki, R. Muto, K. Satou, M. Tomizawa, T. Toyama, M. Uota
KEK, Ibaraki, Japan

Electron cloud instability is presented in most of the high intensity proton rings. During the Slow beam extraction (SX) mode at Main Ring of J-PARC, signals related with its formation were observed. An electron cloud detector is installed downstream of the ElectroStatic Septum (ESS), to measure the electron signal. Additionally, scintillation detector with photomultiplier, a proportional counter and photo-diode were set closely to the electron cloud detector to observe the beam lost. This paper presents the measurements of the electron cloud and some of the conditions which support its creation, for instance the signal of lost particle from the beam loss monitors, the residual gas in the vacuum duct by using vacuum pressure gauges, etc.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB024

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MOPMB025

The Development of 16-Electrode Monitor for Measurement of the Multipole-Moment

140

Y. Nakanishi, A. Ichikawa, A. Minamino, K.G. Nakamura, T. Nakaya
Kyoto University, Kyoto, Japan
T. Koseki, H. Kuboki
KEK, Tokai, Ibaraki, Japan
T. Toyama
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

Funding: This work was supported by MEXT KAKENHI Grant Number 25105002, Grant-in-Aid for Scientific Research on Innovative Areas titled 'Unification and　Development of the Neutrino Science Frontier'
In the J-PARC main ring, the beam intensity is greatly increased to 750 kW or more in near future. Even the beam intensity become higher, the beam loss must be kept at the same level as present. Aiming to make the cause of beam loss clear, we have been developing the beam monitor to measure the beam size. The quadrupole moment is related to the beam size. In principle, monitors with more than four electrodes can measure the quadrupole moment. In addition, two monitors located at the places with different beta functions can measure the emittances and beam sizes, providing the horizontal and vertical beta functions. To obtain more precise quadrupole moment and higher multipoles, we are developing the multi-electrode monitor, tentatively, with 16 electrodes. As a reference of 16-electrode monitor, two 4-electrode BPMs are investigated to measure quadrupole moments. We will present the measurement result of 4-electrode monitors and the status of the development of the 32-electrode monitor.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB025

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WEPOR021

Residual Radiation Monitoring by Beam Loss Monitors at the J-PARC Main Ring

2715

T. Toyama, K. Satou
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
H. Kuboki, H. Nakamura, B. Yee-Rendón
KEK, Ibaraki, Japan
M.J. Shirakata
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

At J-PARC (the Japan Proton Accelerator Research Complex), high intensity proton accelerator, controlling and localizing beam losses and residual radiations are key issue, because the residual radiation limits maintenance work in efficiency and working hours, and then limits machine availability. We are accumulating continuous measurement data of residual radiation after beam stop using beam loss monitors in the Main Ring (MR). The wire cylinder gaseous radiation detectors are used in a proportional counting region. The heads are DC-connected and have a gain as large as 30000 with a bias of -2 kV. We switch the DAQ trigger from "Beam Trigger" to "No Beam Trigger", change the ADC sampling rate to 16 ms, and raise the gain by changing the bias voltage from -1.6 kV to -2.0 kV with a few exceptions when the accelerator operation ends. The offsets are measured with zero bias voltage. Identification of radionuclides has been performed with time decay analysis, with assistance of energy spectrum measurements with the Gamma Ray Spectrometer, Kromek GR1-Spectro.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR021

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THPOY034

Simulations of the Beam Loss Distribution at J-PARC Main Ring

4175

B. Yee-Rendón, H. Kuboki, Y. Sato, K. Satou, M.J. Shirakata, T. Toyama
KEK, Ibaraki, Japan
H. Harada
JAEA/J-PARC, Tokai-mura, Japan

The Japan Proton Accelerator Research Complex (J-PARC) is integrated by a set of high intensity proton accelerators. At this operation level, the monitoring and control of the beam losses and residual radiation are priority for its safe performance and maintenance. At Main Ring (MR), a discrepancy appears between the beam loss signal detected by the monitors and the residual dose measured. To understand this difference and the mechanism that produces these losses, a beam simulation study is implemented using the Strategic Accelerator Design (SAD) and Geometry and Tracking (Geant4) code. The first stage of the survey uses SAD to obtain the location of the losses around the lattice per turn. Then, Geant4 produces the secondary showers in the elements. Finally, we make the extrapolation with the residual radiation and compare with the measurements. The description and results of this work are presented in this paper.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY034

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)