| Co-Investigator(Kenkyū-buntansha) |
TOYAMA Tsuyoshi KEK (National Laboratory for high energy physics), Research Associate, 加速器研究部, 助手 (30207641)
SATOH Hikaru KEK (National Laboratory for high energy physics), Professor, 加速器研究部, 教授 (80100816)
ARENDS H.j. Mainz University, Professor, 原子核物理教室, 教授
REICHERT E. Mainz University, Professor, 物理教室, 教授
ALTHOFF K.h. Bonn University, Emeritus Professor, 物理教室, 名誉教授
REICHERT T. Bonn大学, 物理教室, 教授
HUSMANN D. Bonn University, Professor, 物理教室, 教授
SCHOCH B. Bonn University, Professor, 物理教室, 教授
REICHELT T. Bonn University, Professor
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| Research Abstract |
Recently polarized electron beam is considered as an indispensable tool in particle and nuclear physics, and most of electron accelerators in world have facilities of polarized electron source. They are Bonn, CEBAF,MIT-Bates, Mainz, NIKHEF,Novosibirsk and SLAC etc.
In this program, the main subject is the GDH experiments at MAMI/Mainz and ELSA/Bonn which was proposed in 1993 and 1991, respectively. Since then, developments of polarized electron sources at Bonn and Mainz have been continued. The photocathodes which can produce high polarization and quantum efficiency beam, such as strained GaAs or AlGaAs/GaAs superlattice had been developed intensively at Nagoya university. The application of such photocathodes are expected to make important contributions for Mainz and Bonn experiments.
At Mainz, the superlattice cathode was tested by a 100 KeV gun, and the polarization 62% was obtained with high quantam efficiency of 2.0%. The source could produce a 50 micro-A DC beam, and 10% of this beam could be delivered to the target by MAMI.For GDH experiment, the preparations of polarized beam and target, spectrometers, datataking system to measure the total cross-sections with spin paralell andanti-parallel have been made, and the first machine time is scheduled infall of 1996.
At Bonn, a recently constructed 120 KeV polarized electron source could produce a design-valued intensity of 100 mA for 1 micro-sec laser pulse. The design and construction of accelerating electrodes for this gun were made at Nagoya university. The field emission current between electrodes was suppressed less than 5 nA and it assured the long cathode-lifetime. At moment, 0.2 nA of polarized beam could be extracted from ELSA,and as a next step, a study to overcome a depolarization problem is scheduled in 1996 to accelerate polarized electrons up to 3.5 GeV.
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