IPAC2011 - List of Authors (Takeda, Y.)

Paper

Title

Page

Ultra-high Resolution Observation Device for Carbon Stripper Foil

1740

Y. Takeda, Y. Irie, I. Sugai
KEK, Ibaraki, Japan

To observe a growth process of a pinhole on a HBC-foil due to beam irradiation, an up to 10 um of device for ultra-high resolution observation is needed. For the environment where we use the device for observation is so severe as under high radiation and in vacuum, there is no device available for long-time observation. Then, we designed and created a wholly new method based system which enables constant observation by ultra-high resolution even under high radiation environment. We attempted several experiments, compared materials usable under radiation environment, checked up various optical systems which enables high resolution, and finally developed the best method. As a result, we successfully invented an ultra-high resolution observation device available for monitoring an object about 8 meters distant by 8.3um resolution.

TUPC099

New Measurements of Proton Beam Extinction at J-PARC

1242

K. Yoshimura, Y. Hori, Y. Igarashi, S. Mihara, H. Nishiguchi, Y. Sato, M. Shimamoto, Y. Takeda, M. Uota
KEK, Ibaraki, Japan
M. Aoki, S. Hikida, H. Nakai
Osaka University, Osaka, Japan
Y. Hashimoto
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

Proton beam extinction, defined as a residual to primary ratio of beam intensity, is one of the most important parameters to realize the future muon electron conversion experiment (COMET) proposed at J-PARC. To achieve the required extinction level of 10^-9, we started measuring extinction at main ring (MR) as its first step. According to the various measurements done at the different positions, empty RF buckets of RCS, which were considered to be swept away by the RF chopper, contained about 10^-7 ~ 10^-5 of the main beam pulse due to chopper inefficiency. We have developed a new beam monitor with improved performance for further studies at the abort line. In addition, we have started new measurements at the Hadron experimental hall by using slow-extracted beam. In this paper, we present recent results and future prospect of beam extinction measurements.

THPS036

Development of Thin NCS-foils by N+ Ion Beam Sputtering and Their Characteristics

3499

I. Sugai, H. Kawakami, M. Oyaizu, Y. Takeda
KEK, Ibaraki, Japan
T. Hattori, K.K. Kawasaki
RLNR, Tokyo, Japan

We have developed thin Nitride Carbon Stripper foils (NCS-foil) with a higher nitrogen content by ion beam sputtering　method with reactive nitrogen gas. Such NCS-foils have been demonstrated that the foils in range of 10^-25 ug/m2 have shown long-lifetime as stripper foil against high intensity heavy ion beam bombardment. From the results, we found that the nitrogen element in the carbon foils plays very important role of the foil lifetime. Therefore, in order to investigate further influence of the lifetime on the nitrogen amount in the NCS-foils, we measured the sputtering yield at the different sputtering angles and carbon source materials. We also measured the ratio of nitrogen in carbon foil made at the different sputtering angles, target materials and the sputtering voltages of 4-15 kV by means of RBS method. The foil-lifetime made in above different conditions was measured with a 3.2 MeV Ne⁺ ion beam. The lifetime does not essentially depend on the sputtering angles and the target materials, and the maximum and average lifetimes showed 240 and 40 times longer than that of the CM-best foils.

THPS037

Performance Characteristics of HBC-foils by 650 KeV H⁻ and DC High Intensity Ion Beam Irradiation

3502

I. Sugai, Y. Irie, H. Kawakami, M. Oyaizu, A. Takagi, Y. Takeda
KEK, Ibaraki, Japan
M. Kinsho, Y. Yamazaki, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

Newly developed Hybrid type Boron mixed Carbon stripper foils (HBC-stripper foil) are extensively used for not only J-PARC, for but also LANL-PSR since September of 2007. In order to know further characteristics of the HBC-stripper foils, we measured following parameters; foil lifetimes, thickness reduction, uniformity before and after beam irradiation and foil shrinkage, using 3.2 MeV Ne⁺ DC beam from TIT-Van de Grraff and 650 keV DC proton beam at KEK Cock-Croft accelerators, which are almost the same energy deposition as well as the J-PARC. We also investigated sputtering yield by hydrogen ion beam, thermal conductivity, weight change in heating and density of the HBC-stripper foils. We compared these values with other tested carbon stripper foils such as commercially available carbon foils (CM-foil), synthetic diamond (DM-foil) and nano-tube carbon foils (NTC-foil). Through these experiments, the　HBC-stripper foils showed superior performance characteristics, in especially, on the lifetime at temperature higher than 1800K compared with other tested CM-, DM- and NTC-foils.

WEOAB01

Highly Polarized and High Quantum Efficiency Electron Source Using Transmission-type Photocathode

1950

N. Yamamoto, F. Ichihashi, A. Mano, T. Nakanishi, Y. Takeda, T. Ujihara
Nagoya University, Nagoya, Japan
X.G. Jin
Institute for Advanced Research, Nagoya, Japan

The GaAs-type semiconductor photocathodes (PCs) with a negative electron affinity surface have been used as a polarized electron source and are expected as electron sources for next generation accelerators, such as Linear Colliders and Energy Recovery Linacs. Recently, we have developed transmission-type photocathodes (T-PCs).　By using T-PCs, polarized electron beam is extracted from the back-side of laser irradiation-side.　This scheme offers great merits in designing electron guns, such as short focusing of the laser light for a high brilliance electron beam and a simple geometrical structure avoiding an interference problem between the laser and the electron beam. The layer structure of the MOVPE-grown superlattice photocathode and the performance of 90% polarization, a super high brilliance, and a high quantum efficiency will be reported.

Slides WEOAB01 [6.007 MB]

Paper	Title	Page
TUPS086	Ultra-high Resolution Observation Device for Carbon Stripper Foil	1740
	Y. Takeda, Y. Irie, I. Sugai KEK, Ibaraki, Japan
	To observe a growth process of a pinhole on a HBC-foil due to beam irradiation, an up to 10 um of device for ultra-high resolution observation is needed. For the environment where we use the device for observation is so severe as under high radiation and in vacuum, there is no device available for long-time observation. Then, we designed and created a wholly new method based system which enables constant observation by ultra-high resolution even under high radiation environment. We attempted several experiments, compared materials usable under radiation environment, checked up various optical systems which enables high resolution, and finally developed the best method. As a result, we successfully invented an ultra-high resolution observation device available for monitoring an object about 8 meters distant by 8.3um resolution.

TUPC099	New Measurements of Proton Beam Extinction at J-PARC	1242
	K. Yoshimura, Y. Hori, Y. Igarashi, S. Mihara, H. Nishiguchi, Y. Sato, M. Shimamoto, Y. Takeda, M. Uota KEK, Ibaraki, Japan M. Aoki, S. Hikida, H. Nakai Osaka University, Osaka, Japan Y. Hashimoto J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	Proton beam extinction, defined as a residual to primary ratio of beam intensity, is one of the most important parameters to realize the future muon electron conversion experiment (COMET) proposed at J-PARC. To achieve the required extinction level of 10^-9, we started measuring extinction at main ring (MR) as its first step. According to the various measurements done at the different positions, empty RF buckets of RCS, which were considered to be swept away by the RF chopper, contained about 10^-7 ~ 10^-5 of the main beam pulse due to chopper inefficiency. We have developed a new beam monitor with improved performance for further studies at the abort line. In addition, we have started new measurements at the Hadron experimental hall by using slow-extracted beam. In this paper, we present recent results and future prospect of beam extinction measurements.

THPS036	Development of Thin NCS-foils by N+ Ion Beam Sputtering and Their Characteristics	3499
	I. Sugai, H. Kawakami, M. Oyaizu, Y. Takeda KEK, Ibaraki, Japan T. Hattori, K.K. Kawasaki RLNR, Tokyo, Japan
	We have developed thin Nitride Carbon Stripper foils (NCS-foil) with a higher nitrogen content by ion beam sputtering　method with reactive nitrogen gas. Such NCS-foils have been demonstrated that the foils in range of 10^-25 ug/m2 have shown long-lifetime as stripper foil against high intensity heavy ion beam bombardment. From the results, we found that the nitrogen element in the carbon foils plays very important role of the foil lifetime. Therefore, in order to investigate further influence of the lifetime on the nitrogen amount in the NCS-foils, we measured the sputtering yield at the different sputtering angles and carbon source materials. We also measured the ratio of nitrogen in carbon foil made at the different sputtering angles, target materials and the sputtering voltages of 4-15 kV by means of RBS method. The foil-lifetime made in above different conditions was measured with a 3.2 MeV Ne⁺ ion beam. The lifetime does not essentially depend on the sputtering angles and the target materials, and the maximum and average lifetimes showed 240 and 40 times longer than that of the CM-best foils.

THPS037	Performance Characteristics of HBC-foils by 650 KeV H⁻ and DC High Intensity Ion Beam Irradiation	3502
	I. Sugai, Y. Irie, H. Kawakami, M. Oyaizu, A. Takagi, Y. Takeda KEK, Ibaraki, Japan M. Kinsho, Y. Yamazaki, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	Newly developed Hybrid type Boron mixed Carbon stripper foils (HBC-stripper foil) are extensively used for not only J-PARC, for but also LANL-PSR since September of 2007. In order to know further characteristics of the HBC-stripper foils, we measured following parameters; foil lifetimes, thickness reduction, uniformity before and after beam irradiation and foil shrinkage, using 3.2 MeV Ne⁺ DC beam from TIT-Van de Grraff and 650 keV DC proton beam at KEK Cock-Croft accelerators, which are almost the same energy deposition as well as the J-PARC. We also investigated sputtering yield by hydrogen ion beam, thermal conductivity, weight change in heating and density of the HBC-stripper foils. We compared these values with other tested carbon stripper foils such as commercially available carbon foils (CM-foil), synthetic diamond (DM-foil) and nano-tube carbon foils (NTC-foil). Through these experiments, the　HBC-stripper foils showed superior performance characteristics, in especially, on the lifetime at temperature higher than 1800K compared with other tested CM-, DM- and NTC-foils.

WEOAB01	Highly Polarized and High Quantum Efficiency Electron Source Using Transmission-type Photocathode	1950
	N. Yamamoto, F. Ichihashi, A. Mano, T. Nakanishi, Y. Takeda, T. Ujihara Nagoya University, Nagoya, Japan X.G. Jin Institute for Advanced Research, Nagoya, Japan
	The GaAs-type semiconductor photocathodes (PCs) with a negative electron affinity surface have been used as a polarized electron source and are expected as electron sources for next generation accelerators, such as Linear Colliders and Energy Recovery Linacs. Recently, we have developed transmission-type photocathodes (T-PCs).　By using T-PCs, polarized electron beam is extracted from the back-side of laser irradiation-side.　This scheme offers great merits in designing electron guns, such as short focusing of the laser light for a high brilliance electron beam and a simple geometrical structure avoiding an interference problem between the laser and the electron beam. The layer structure of the MOVPE-grown superlattice photocathode and the performance of 90% polarization, a super high brilliance, and a high quantum efficiency will be reported.
	Slides WEOAB01 [6.007 MB]