IPAC2011 - List of Authors (Ikegami, M.)

Paper

Title

Page

Possibility of longitudinal painting injection with debuncher system in J-PARC linac

3505

G.H. Wei
KEK/JAEA, Ibaraki-Ken, Japan
M. Ikegami
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

J-PARC linac is presently operating with the output energy of 181 MeV and providing a negative hydrogen beam to the succeeding 3-GeV synchrotron. To achieve the design beam power of 1 MW from the synchrotron, we plan to upgrade the linac beam energy to 400 MeV. In the energy upgrade, we replace the debuncher system installed between the linac and synchrotron. The main roles of the debuncher system are to correct the momentum jitter and to control the momentum spread at the ring injection. Usually, we don’t assume acceleration or deceleration with the debuncher cavities except for passive momentum jitter correction. However, we are studying the possibility of actively controlling the center momentum with debuncher cavities to enable longitudinal painting injection into the succeeding ring as a potential new feature. If it finds feasible, it would provide an additional tuning knob to mitigate the beam loss in the synchrotron. In this paper, we show a beam dynamics design of the new debuncher system with emphasis on the possibility of its application for the longitudinal painting injection.

MOOCB01

Study on the Realignment Plan for J-PARC Linac after the Tohoku Earthquake in Japan

44

M. Ikegami
KEK, Ibaraki, Japan
T. Morishita
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

A 9.0-magnitude earthquake struck eastern Japan on March 11, 2011, and it gave rise to damages to the buildings of the J-PARC facilities. In particular, the earthquake caused a deformation of the J-PARC linac tunnel resulting an alignment error of several tens of millimeters in both horizontal and vertical directions. It also caused a change in the relative position between the linac and other facilities of J-PARC complex. To restore the beam operation, we should establish a reasonable realignment plan for J-PARC linac taking various constraints into account and possibly tolerating some residual misalignment. In this paper, we show a study on the realignment plan for J-PARC linac including evaluation of the effect of residual misalignment with particle simulations.

Slides MOOCB01 [2.659 MB]

TUPC100

Longitudinal Beam Profile Measurement at J-PARC Separated Drift Tube Linac

1245

T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan
M. Ikegami
KEK, Ibaraki, Japan
A. Miura, G.H. Wei
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
H. Sako
JAEA, Ibaraki-ken, Japan

We measured longitudinal beam profile at Separated Drift Tube Linac (SDTL) injection part by scanning beam transmission and beamloss at the downstream of SDTL section by changing SDTL injection phase. As the beam goes to acceptance edge, part of the beam which is out of acceptance isn't accelerate and finally it is lost by hitting to beam duct. Thus beam transmission shows sliced bunch shape by acceptance edge, it is possible to reconstruct the beam bunch shape. The result shows about 60% wider profile in both phi and E direction against to design.

TUPC104

Beam Loss Detected by Scintillation Monitor

1257

A. Miura, K. Hasegawa, T. Maruta, N. Ouchi, H. Sako
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Z. Igarashi, M. Ikegami, T. Miyao
KEK, Ibaraki, Japan

Ar gas proportional BLMs have measured the beam loss through operations, but they are also sensitive to background noise of X-ray emitted from RF cavities. We have tried to measure the beam loss using scintillation monitors which would bring more accurate beam loss measurements with suppression of X-ray noise. We measured beam loss using scintillation beam loss monitors. Because this scintillation BLM is sensitive for low energy gamma-rays and fast neutrons, small signals from X-rays would be also detected. As the measurement results, a good signal to noise ratio is observed for the scintillation monitor with quite low sensitivity to the background X-ray. And many single events are observed in the intermediate pulse bunch with about 600 ns as pulse width. In addition, because we fabricated the filter and integrated circuit, total amount of X-ray noise can become smaller. We obtained the good performances of scintillation BLM with small effect of X-ray noise. This monitor can be used for beam loss measurement and a knob for tuning. Furthermore, because the detail structure can be detected, this monitor could be employed for another diagnostic device.

WEPC144

Beam Monitor Deformation by Tohoku Earthquake and its Recovery Project

2328

A. Miura, K. Hasegawa, H. Oguri, N. Ouchi
JAEA/J-PARC, Tokai-mura, Japan
Z. Igarashi, M. Ikegami, T. Miyao
KEK, Ibaraki, Japan

On March 11, 2011, the biggest earthquake occurred at Tohoku and North Kanto area in Japan. This earthquake and related ones have attacked J-PARC accelerators and caused the big damage. As for the linac beam monitors, some commissioning tools which were installed in the linac had damage and the air leakage was observed. In the first step of the recovery work, we checked the damage and put the emergency treatment for vacuum of the cavities. All beam monitors were observed, the leak from the vacuum devices was tested and the conduction of the signal cables was measured to compare the previous performance. In the next step, we started to order the new devices which should be replaced and to obtain the calibration data. We found the leakage from the phase monitors. The earthquake caused the crack and deformation at the welded points between the metallic parts and ceramic parts. And a wire of the profile monitor was broken while the beam position monitors have no damage. We are continuing this recovery work ongoingly.

WEPS046

Longitudinal Beam Acceptance of J-PARC Drift Tube Linac

2592

T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan
M. Ikegami
KEK, Ibaraki, Japan
A. Miura, G.H. Wei
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
H. Sako
JAEA, Ibaraki-ken, Japan

The longitudinal acceptance of the J-PARC Drift Tube Linac (DTL) was measured by synchronous phase scan method. The IMPACT simulation indicated DTL longitudinal acceptance is shrinked if the DTL tank level reduced, but beam energy finally acheved at the Linac is almost same as the case of nominal tank level. We measured the acceptance and confirmed the simulation is correct.

WEPS049

Floor Deformation of J-PARC Linac after the Tohoku Earthquake in Japan

2601

T. Morishita, H. Asano
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
M. Ikegami
KEK, Ibaraki, Japan

J-PARC linac has finalized its precise alignment at the end of summer 2006, and the beam provision to the Rapid Cycling Synchrotron has been started at Sept. 2007. Since then, the deformation of the accelerator tunnel is small enough to keep the soundness of the alignment accuracy. Therefore, the linac has been operated without realignment of the accelerator components for these four years. However, the alignment has seriously been damaged due to the large earthquake at Mar. 11th, 2011 in eastern Japan. Now, work for restoration is being continued. In this paper, the deformation of the linac tunnel floor due to the earthquake is reported. Since then, aftershock happens frequently. We also report the stability of the tunnel floor.

Paper	Title	Page
THPS038	Possibility of longitudinal painting injection with debuncher system in J-PARC linac	3505
	G.H. Wei KEK/JAEA, Ibaraki-Ken, Japan M. Ikegami J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	J-PARC linac is presently operating with the output energy of 181 MeV and providing a negative hydrogen beam to the succeeding 3-GeV synchrotron. To achieve the design beam power of 1 MW from the synchrotron, we plan to upgrade the linac beam energy to 400 MeV. In the energy upgrade, we replace the debuncher system installed between the linac and synchrotron. The main roles of the debuncher system are to correct the momentum jitter and to control the momentum spread at the ring injection. Usually, we don’t assume acceleration or deceleration with the debuncher cavities except for passive momentum jitter correction. However, we are studying the possibility of actively controlling the center momentum with debuncher cavities to enable longitudinal painting injection into the succeeding ring as a potential new feature. If it finds feasible, it would provide an additional tuning knob to mitigate the beam loss in the synchrotron. In this paper, we show a beam dynamics design of the new debuncher system with emphasis on the possibility of its application for the longitudinal painting injection.

MOOCB01	Study on the Realignment Plan for J-PARC Linac after the Tohoku Earthquake in Japan	44
	M. Ikegami KEK, Ibaraki, Japan T. Morishita JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	A 9.0-magnitude earthquake struck eastern Japan on March 11, 2011, and it gave rise to damages to the buildings of the J-PARC facilities. In particular, the earthquake caused a deformation of the J-PARC linac tunnel resulting an alignment error of several tens of millimeters in both horizontal and vertical directions. It also caused a change in the relative position between the linac and other facilities of J-PARC complex. To restore the beam operation, we should establish a reasonable realignment plan for J-PARC linac taking various constraints into account and possibly tolerating some residual misalignment. In this paper, we show a study on the realignment plan for J-PARC linac including evaluation of the effect of residual misalignment with particle simulations.
	Slides MOOCB01 [2.659 MB]

TUPC100	Longitudinal Beam Profile Measurement at J-PARC Separated Drift Tube Linac	1245
	T. Maruta KEK/JAEA, Ibaraki-Ken, Japan M. Ikegami KEK, Ibaraki, Japan A. Miura, G.H. Wei JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan H. Sako JAEA, Ibaraki-ken, Japan
	We measured longitudinal beam profile at Separated Drift Tube Linac (SDTL) injection part by scanning beam transmission and beamloss at the downstream of SDTL section by changing SDTL injection phase. As the beam goes to acceptance edge, part of the beam which is out of acceptance isn't accelerate and finally it is lost by hitting to beam duct. Thus beam transmission shows sliced bunch shape by acceptance edge, it is possible to reconstruct the beam bunch shape. The result shows about 60% wider profile in both phi and E direction against to design.

TUPC104	Beam Loss Detected by Scintillation Monitor	1257
	A. Miura, K. Hasegawa, T. Maruta, N. Ouchi, H. Sako JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan Z. Igarashi, M. Ikegami, T. Miyao KEK, Ibaraki, Japan
	Ar gas proportional BLMs have measured the beam loss through operations, but they are also sensitive to background noise of X-ray emitted from RF cavities. We have tried to measure the beam loss using scintillation monitors which would bring more accurate beam loss measurements with suppression of X-ray noise. We measured beam loss using scintillation beam loss monitors. Because this scintillation BLM is sensitive for low energy gamma-rays and fast neutrons, small signals from X-rays would be also detected. As the measurement results, a good signal to noise ratio is observed for the scintillation monitor with quite low sensitivity to the background X-ray. And many single events are observed in the intermediate pulse bunch with about 600 ns as pulse width. In addition, because we fabricated the filter and integrated circuit, total amount of X-ray noise can become smaller. We obtained the good performances of scintillation BLM with small effect of X-ray noise. This monitor can be used for beam loss measurement and a knob for tuning. Furthermore, because the detail structure can be detected, this monitor could be employed for another diagnostic device.

WEPC144	Beam Monitor Deformation by Tohoku Earthquake and its Recovery Project	2328
	A. Miura, K. Hasegawa, H. Oguri, N. Ouchi JAEA/J-PARC, Tokai-mura, Japan Z. Igarashi, M. Ikegami, T. Miyao KEK, Ibaraki, Japan
	On March 11, 2011, the biggest earthquake occurred at Tohoku and North Kanto area in Japan. This earthquake and related ones have attacked J-PARC accelerators and caused the big damage. As for the linac beam monitors, some commissioning tools which were installed in the linac had damage and the air leakage was observed. In the first step of the recovery work, we checked the damage and put the emergency treatment for vacuum of the cavities. All beam monitors were observed, the leak from the vacuum devices was tested and the conduction of the signal cables was measured to compare the previous performance. In the next step, we started to order the new devices which should be replaced and to obtain the calibration data. We found the leakage from the phase monitors. The earthquake caused the crack and deformation at the welded points between the metallic parts and ceramic parts. And a wire of the profile monitor was broken while the beam position monitors have no damage. We are continuing this recovery work ongoingly.

WEPS046	Longitudinal Beam Acceptance of J-PARC Drift Tube Linac	2592
	T. Maruta KEK/JAEA, Ibaraki-Ken, Japan M. Ikegami KEK, Ibaraki, Japan A. Miura, G.H. Wei JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan H. Sako JAEA, Ibaraki-ken, Japan
	The longitudinal acceptance of the J-PARC Drift Tube Linac (DTL) was measured by synchronous phase scan method. The IMPACT simulation indicated DTL longitudinal acceptance is shrinked if the DTL tank level reduced, but beam energy finally acheved at the Linac is almost same as the case of nominal tank level. We measured the acceptance and confirmed the simulation is correct.

WEPS049	Floor Deformation of J-PARC Linac after the Tohoku Earthquake in Japan	2601
	T. Morishita, H. Asano JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan M. Ikegami KEK, Ibaraki, Japan
	J-PARC linac has finalized its precise alignment at the end of summer 2006, and the beam provision to the Rapid Cycling Synchrotron has been started at Sept. 2007. Since then, the deformation of the accelerator tunnel is small enough to keep the soundness of the alignment accuracy. Therefore, the linac has been operated without realignment of the accelerator components for these four years. However, the alignment has seriously been damaged due to the large earthquake at Mar. 11th, 2011 in eastern Japan. Now, work for restoration is being continued. In this paper, the deformation of the linac tunnel floor due to the earthquake is reported. Since then, aftershock happens frequently. We also report the stability of the tunnel floor.