IPAC2011 - List of Authors (Nakanishi, T.)

Paper

Title

Page

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]

THPS039

Diffusion of a Circulating Beam by the RF-Knockout with a Spectrum including Many Bands

3508

M. Tashiro, T. Nakanishi
Nihon University, Narashino, Chiba, Japan

The fast control of beam spill extracted from a synchrotron is a key function for the spot scanning irradiation in cancer therapy application. The authors have proposed the extraction method for the application which uses the control of a quadruple field of fast response as well as the RFKO (QAR method). The RF signal for the RFKO should cover a frequency band corresponding to a tune spread. A simulation with continuous RFKO operation, however, showed a spill intensity changes with time largely with only this band. The large change of spill is due to not uniform diffusion of circulating beam and it makes a constant spill difficult in the QAR method. A wider band gives a uniform spill, but it requires a larger Amp power. We proposed a spectrum including many bands around the resonances to reduce the power, since the bands outside around the resonances do not contribute to the diffusion. Such a spectrum has also an advantage to increase spill intensity for the QAR method, using a band so that the RFKO diffuses more inside particles of the separatrix but also it affects little them near the boundary. We can extract several times particles with a same shrink ratio of the separatrix.

THPC144

The Construction Status of Beam Transport Line from XFEL-linac to SPring-8 Storage Ring

3224

C. Mitsuda, N. Azumi, T. Fujita, K. Fukami, H. Kimura, H. Ohkuma, M. Oishi, Y. Okayasu, M. Shoji, K. Tsumaki, T. Watanabe
JASRI/SPring-8, Hyogo-ken, Japan
M. Hasegawa, Y. Maeda, T. Nakanishi, Y. Tukamoto, M. Yamashita
SES, Hyogo-pref., Japan
N. Kumagai, S. Matsui
RIKEN/SPring-8, Hyogo, Japan

The beam transport line from XFEL-linac to SPring-8 storage ring is now under construction to use the ultra short bunched electron beam at the storage ring. The newly constructed line is about 300 m, which is just a half of the whole path from the XFEL linac to the storage ring. The beam extracted from XFEL-linac is guided to the beam transport tunnel connected to the matching section of booster synchrotron bending by 55.2 degrees horizontally and by 10.0 degrees vertically. A double-bend based lattice was adopted to reasonably suppress emittance growth and bunch lengthening. Supposing a bunch length and horizontal emittance at the exit of the XFEL-linac are estimated about 100 fs and 0.04 nmrad respectively, it is expected that the current beam emittance in storage ring is improved to about 0.4 nmrad and almost same bunch length including coherent synchrotron radiation effect. In 2010, the construction of extracting part from XFEL-linac was completed and we finished the installation and alignment of main components. The conceptual design and construction status of transport line will be presented with the emphasis on the detail magnet design and the fabrication.

Paper	Title	Page
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]

THPS039	Diffusion of a Circulating Beam by the RF-Knockout with a Spectrum including Many Bands	3508
	M. Tashiro, T. Nakanishi Nihon University, Narashino, Chiba, Japan
	The fast control of beam spill extracted from a synchrotron is a key function for the spot scanning irradiation in cancer therapy application. The authors have proposed the extraction method for the application which uses the control of a quadruple field of fast response as well as the RFKO (QAR method). The RF signal for the RFKO should cover a frequency band corresponding to a tune spread. A simulation with continuous RFKO operation, however, showed a spill intensity changes with time largely with only this band. The large change of spill is due to not uniform diffusion of circulating beam and it makes a constant spill difficult in the QAR method. A wider band gives a uniform spill, but it requires a larger Amp power. We proposed a spectrum including many bands around the resonances to reduce the power, since the bands outside around the resonances do not contribute to the diffusion. Such a spectrum has also an advantage to increase spill intensity for the QAR method, using a band so that the RFKO diffuses more inside particles of the separatrix but also it affects little them near the boundary. We can extract several times particles with a same shrink ratio of the separatrix.

THPC144	The Construction Status of Beam Transport Line from XFEL-linac to SPring-8 Storage Ring	3224
	C. Mitsuda, N. Azumi, T. Fujita, K. Fukami, H. Kimura, H. Ohkuma, M. Oishi, Y. Okayasu, M. Shoji, K. Tsumaki, T. Watanabe JASRI/SPring-8, Hyogo-ken, Japan M. Hasegawa, Y. Maeda, T. Nakanishi, Y. Tukamoto, M. Yamashita SES, Hyogo-pref., Japan N. Kumagai, S. Matsui RIKEN/SPring-8, Hyogo, Japan
	The beam transport line from XFEL-linac to SPring-8 storage ring is now under construction to use the ultra short bunched electron beam at the storage ring. The newly constructed line is about 300 m, which is just a half of the whole path from the XFEL linac to the storage ring. The beam extracted from XFEL-linac is guided to the beam transport tunnel connected to the matching section of booster synchrotron bending by 55.2 degrees horizontally and by 10.0 degrees vertically. A double-bend based lattice was adopted to reasonably suppress emittance growth and bunch lengthening. Supposing a bunch length and horizontal emittance at the exit of the XFEL-linac are estimated about 100 fs and 0.04 nmrad respectively, it is expected that the current beam emittance in storage ring is improved to about 0.4 nmrad and almost same bunch length including coherent synchrotron radiation effect. In 2010, the construction of extracting part from XFEL-linac was completed and we finished the installation and alignment of main components. The conceptual design and construction status of transport line will be presented with the emphasis on the detail magnet design and the fabrication.