IPAC2013 - List of Authors (Kamitani, T.)

Paper	Title	Page
MOPFI017	SuperKEKB Positron Source Target Protection Scheme	315
	L. Zang, T. Kamitani KEK, Ibaraki, Japan
	The SuperKEKB requires an intense beam with a large number of positrons, which is generated by a high energy electron beam strike on a solid tungsten target. The cascade shower in the target deposits large amount of energy in the material leading to target damage. The pulsed electron beam distributed the energy non-uniformly over the target. In that case, a mechanical stress appears due to the large thermal gradient during each pulse, which could potentially destroy the target. Based on the analysis of the SLAC damaged target, peak energy deposition density (PEDD) should not exceed 35 J/g to ensure a long term of safe operation. One way of reducing PEDD is increasing the beam spot size. Hence we proposed a target protection scheme, in which a protection target is placed upstream of generation target as a spoiler. The aim is to maintain the generation target’s PEDD below 35 J/g even with a point primary electron beam. In this paper, we will introduce graphite, aluminum and copper as the protection target material candidates. And also present the PEDD and positron yield evaluation as a function of various parameters such as protection target thickness and drift space.

MOPFI018	Design Study of a New Large Aperture Flux Concentrator	318
	L. Zang, M. Akemoto, S. Fukuda, K. Furukawa, T. Higo, K. Kakihara, T. Kamitani, Y. Ogawa, H. Someya, T. Takatomi KEK, Ibaraki, Japan
	For high luminosity electron-positron colliders, intense positron beam production is one of the key issues. Flux Concentrator (FC) is a pulsed solenoid that can generate high magnetic field of several Tesla and is often used for focusing positrons emerged from a production target. It works as an optical matching device in a positron capture section. With this device, high capture efficiency is achieved. In this paper, we will introduce a new design of a FC for the SuperKEKB positron source. The advantages of the new design are: 1. the aperture could be doubled of the previous design, 2. the transverse components are only 1/10 of the previous design, 3. maintain the same high peak longitudinal field. The new FC modeling has been done in CST Studio and we will report the results of new FC field evaluation. In order to calculate the positron yield and capture efficiency, a tracking simulation to the end of capture section has also been carried out, which is also included in this paper.

TUPME010	High-intensity and Low-emittance Upgrade of 7-GeV Injector Linac towards SuperKEKB	1583
	K. Furukawa, M. Akemoto, D.A. Arakawa, Y. Arakida, A. Enomoto, S. Fukuda, H. Honma, R. Ichimiya, N. Iida, M. Ikeda, E. Kadokura, K. Kakihara, T. Kamitani, H. Katagiri, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Miura, F. Miyahara, T. Mori, H. Nakajima, K. Nakao, T. Natsui, Y. Ogawa, S. Ohsawa, F. Qiu, M. Satoh, T. Shidara, A. Shirakawa, H. Sugimoto, T. Suwada, T. Takatomi, T. Takenaka, M. Tanaka, Y. Yano, K. Yokoyama, M. Yoshida, L. Zang, X. Zhou KEK, Ibaraki, Japan D. Satoh TIT, Tokyo, Japan
	After a decade of successful operation at KEKB a new electron/positron collider, SuperKEKB, is being constructed to commission within FY2014. It aims at a luminosity of 8 x 10³⁵ /s.cm², 40-times higher than that of KEKB, in order to study the flavor physics of elementary particles further, by mainly squeezing the beams at the collision point. The injector linac should provide high-intensity and low-emittance beams of 7-GeV electron and 4-GeV positron by newly installing a RF-gun, a flux concentrator, and a damping ring with careful emittance and energy management. It also have to perform simultaneous top-up injections into four storage rings by pulse-to-pulse beam modulations not to interfare between three facilities of SuperKEKB, Photon Factory and PF-AR. This paper describes the injector design decisions and present status of the construction.

Paper

Title

Page

SuperKEKB Positron Source Target Protection Scheme

315

L. Zang, T. Kamitani
KEK, Ibaraki, Japan

The SuperKEKB requires an intense beam with a large number of positrons, which is generated by a high energy electron beam strike on a solid tungsten target. The cascade shower in the target deposits large amount of energy in the material leading to target damage. The pulsed electron beam distributed the energy non-uniformly over the target. In that case, a mechanical stress appears due to the large thermal gradient during each pulse, which could potentially destroy the target. Based on the analysis of the SLAC damaged target, peak energy deposition density (PEDD) should not exceed 35 J/g to ensure a long term of safe operation. One way of reducing PEDD is increasing the beam spot size. Hence we proposed a target protection scheme, in which a protection target is placed upstream of generation target as a spoiler. The aim is to maintain the generation target’s PEDD below 35 J/g even with a point primary electron beam. In this paper, we will introduce graphite, aluminum and copper as the protection target material candidates. And also present the PEDD and positron yield evaluation as a function of various parameters such as protection target thickness and drift space.

MOPFI018

Design Study of a New Large Aperture Flux Concentrator

318

L. Zang, M. Akemoto, S. Fukuda, K. Furukawa, T. Higo, K. Kakihara, T. Kamitani, Y. Ogawa, H. Someya, T. Takatomi
KEK, Ibaraki, Japan

For high luminosity electron-positron colliders, intense positron beam production is one of the key issues. Flux Concentrator (FC) is a pulsed solenoid that can generate high magnetic field of several Tesla and is often used for focusing positrons emerged from a production target. It works as an optical matching device in a positron capture section. With this device, high capture efficiency is achieved. In this paper, we will introduce a new design of a FC for the SuperKEKB positron source. The advantages of the new design are: 1. the aperture could be doubled of the previous design, 2. the transverse components are only 1/10 of the previous design, 3. maintain the same high peak longitudinal field. The new FC modeling has been done in CST Studio and we will report the results of new FC field evaluation. In order to calculate the positron yield and capture efficiency, a tracking simulation to the end of capture section has also been carried out, which is also included in this paper.

TUPME010

High-intensity and Low-emittance Upgrade of 7-GeV Injector Linac towards SuperKEKB

1583

K. Furukawa, M. Akemoto, D.A. Arakawa, Y. Arakida, A. Enomoto, S. Fukuda, H. Honma, R. Ichimiya, N. Iida, M. Ikeda, E. Kadokura, K. Kakihara, T. Kamitani, H. Katagiri, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Miura, F. Miyahara, T. Mori, H. Nakajima, K. Nakao, T. Natsui, Y. Ogawa, S. Ohsawa, F. Qiu, M. Satoh, T. Shidara, A. Shirakawa, H. Sugimoto, T. Suwada, T. Takatomi, T. Takenaka, M. Tanaka, Y. Yano, K. Yokoyama, M. Yoshida, L. Zang, X. Zhou
KEK, Ibaraki, Japan
D. Satoh
TIT, Tokyo, Japan

After a decade of successful operation at KEKB a new electron/positron collider, SuperKEKB, is being constructed to commission within FY2014. It aims at a luminosity of 8 x 10³⁵ /s.cm², 40-times higher than that of KEKB, in order to study the flavor physics of elementary particles further, by mainly squeezing the beams at the collision point. The injector linac should provide high-intensity and low-emittance beams of 7-GeV electron and 4-GeV positron by newly installing a RF-gun, a flux concentrator, and a damping ring with careful emittance and energy management. It also have to perform simultaneous top-up injections into four storage rings by pulse-to-pulse beam modulations not to interfare between three facilities of SuperKEKB, Photon Factory and PF-AR. This paper describes the injector design decisions and present status of the construction.