Measurement of emittance for electron bunches compressed by velocity bunching via double-slit-scan method

Iijima, Hokuto; Hajima, Ryoichi; Uesaka, Mitsuru*; Sakumi, Akira*; Sakamoto, Fumito*; Ueda, Toru*

Proceedings of 2nd Annual Meeting of Particle Accelerator Society of Japan and 30th Linear Accelerator Meeting in Japan, p.501 - 503, 2005/07

We report the availability of velocity bunching in an energy recovery linac (ERL) by a numerical analysis, and the plan of precise measurement of bunching emittance via a double-slit-scan method. The simulation performed for eight TESLA-type cavities reveals successful bunch compression from 3.2 ps to 0.17 ps. Since the residual energy spread after velocity bunching is considerably smaller than the correlated energy spread required for magnetic compression through a recirculation loop, velocity bunching is useful to realized short-pulse and high-brightness X-rays by ERL. The emittance of velocity bunching was calculated to be 1.5 mm.mrad for the bunch charge of 77pC without the emittance compensation by an external solenoid field. Although the emittance growth due to the space-charge effect was small in the simulation, it is necessary to evaluate the emittance-growth mechanism under velocity bunching. Therefore, the emittance measurement via double-slit-scan method is carrying out in the UTNL-18L.

Current status of ultrafast pulse radiolysis at NPS, University of Tokyo

Muroya, Yusa*; Lin, M.; Han, Z.*; Kumagai, Yuta; Sakumi, Akira*; Ueda, Toru*; Uesaka, Mitsuru*; Katsumura, Yosuke

no journal, , 

The Ultra-fast pulse radiolysis system applied to high temperature radiolysis

Muroya, Yusa*; Lin, M.; Han, Z.*; Sakumi, Akira*; Ueda, Toru*; Katsumura, Yosuke

no journal, , 

An ultra-fast pulse radiolysis system based on pulse-and-probe method has been developed. The system consists of a 22-MeV S-band electron linac and a femtosecond Ti:Sapphire laser. Being the fs fundamental laser (795 nm) split into two, half of the laser beam is injected into the laser photocathode RF-gun to generate electron beam after converted into third harmonics (265 nm), and the other half is used as a probe laser. Since the wavelength of the probe light can be converted into variable wavelengths (535-2600 nm) by an optical parametric amplifier (TOPAS, Light Conversion Co. Ltd), transient absorption spectroscopy in wide wavelength range can be performed efficiently. Recently, the laser photocathode has been improved by replacing Mg by CsTe. Owing to high quantum efficiency of CsTe, better beam quality was realized such as 2 nC in charge per pulse, 2 ps in beam width (FWHM) and 3 mm in diameter of full beam size. This system has been utilized to study initial yields and transient behaviors of presolvated and solvated electrons in water and various alcohols.

High temperature-ultrafast pulse radiolysis

Muroya, Yusa*; Lin, M.; Han, Z.*; Fu, H.*; Yamashita, Shinichi; Sakumi, Akira*; Ueda, Toru*; Katsumura, Yosuke

no journal, , 

In order to investigate radiation-induced fast phenomena in solutions such as water and alcohols at extreme conditions (high temperature and pressure), a new high temperature-ultrafast pulse radiolysis system was developed, which was previously applicable only to the experiment at ambient condition. After the setup of the pulse radiolysis system a preliminary experiment, transient absorption spectroscopy of hydrated electron within a few nanosecond at elevated temperature from room temperature up to 300 C, was performed.