55264755
Development of an Optical Resonant Cavity for the LCS Experiment at cERL
A nondestructive assay method of isotopes by using quasi-monochromatic gamma-rays based on laser-Compton scattering (LCS) is under development. In order to demon- strate the accelerator and the laser performance required for the gamma-ray source, a LCS experiment is planned at Compact ERL (cERL) at KEK. An optical cavity which can achieve high finesse and small waist size is under construc- tion for the LCS experiment. The new optical cavity com- prises two sets of planar 4-mirror cavities.
203217954
Development of an intense positron source using a crystal-amorphous hybrid target for linear colliders
In a conventional positron source driven by a few GeV electron beam, a high amount of heat is loaded into a positron converter target to generate intense positrons required by linear colliders, and which would eventually damage the converter target. A hybrid target, composed of a single crystal target as a radiator of intense gamma-rays, and an amorphous converter target placed downstream of the crystal, was proposed as a scheme which could overcome the problem. This paper describes the development of an intense positron source with the hybrid target. A series of experiments on positron generation with the hybrid target has been carried out with a 8-GeV electron beam at the KEKB linac. We observed that positron yield from the hybrid target increased when the incident electron beam was aligned to the crystal axis and exceeded the one from the conventional target with the converter target of the same thickness, when its thickness is less than about 2 radiation length. The measurements in the temperature rise of the amorphous converter target was successfully carried out by use of thermocouples. These results lead to establishment to the evaluation of the hybrid target as an intense positron source.
67793170
GAMMA-RAYS GENERATION WITH 3D 4-MIRROR CAVITY FOR ILC POLARIZED POSITRON SOURCE
We are developing a ILC polarized positron source based on the laser-Compton scattering. We have already performed a photon generation experiment at the KEK-ATF using a Fabry-Perot type 2-mirror laser pulse stacking cavity [1]. The laser pulses are accumulated and their power was enhanced in the Fabry-Perot cavity. In order further improve performance of the laser power enhancement, a new three dimensional 4-mirror cavity is designed. In this article, we report status of the photon generation experiment.
54800032
Development of a three dimensional four mirror optical cavity for laser-Compton scattering
Abstract This paper describes a design and performance of a three-dimensional 4-mirror optical cavity for development of intense photon sources by laser-Compton scattering. We achieved the finesse of 4000 and average power of 2.6 kW in the cavity with the vertical laser beam spot size of 13 ± 1 μ m in σ at the laser–electron interaction point. As a result, we observed 124±1 photons with average energy of 24 MeV per beam crossing, which corresponds to the generation of 2.7×10 8 photons per second.
55633316
Construction of a Laser Compton Scattered Photon Source at cERL
A high intensity -ray source from the laser Compton scattering (LCS) by an electron beam in an energy-recovery linac (ERL) is a key technology for a nondestructive assay system to identify nuclear materials. In order to demonstrate accelerator and laser technologies required for a LCS photon generation, a LCS photon source is under construction at the Compact ERL (cERL). The LCS photon source consists of a mode-locked fiber laser and a laser enhancement cavity. A beamline and an experimental hatch are also under construction. The commissioning of the LCS photon source will be started in February 2015 and LCS photon generation is scheduled in March 2015.
126251426
Experimental study of the rare decays K0(L) ---> mu e, K0(L) ---> e e, and K0(L) ---> mu mu and K0(L) ---> e e e e
14721989
Beam Test Of The SDC Double-sided Silicon Strip Detector
A beam test was executed to evaluate the behavior of the first prototype radiation-hard double-sided silicon microstrip sensor for the SDC silicon tracking system. Pions of 4 GeV/c in a test bcamline at KEK illuminated three planes of detectors. Thc signals wcrc amplified, shaped, and discriminated with TEKZ bipolar analog LSI's, and the on-off levels were sampled at l0MHz clock with CMOS digiwl LSI's, asynchronously with beam triggers. The detectors were rotated in null and 1 .O Tesla magnetic fields. The efficiencies were found to be 98-9996. The position resolutions were 12.5pm. where the multi-strip hit fraction was 30-40%. There was no essential difference in the performance of the pand the n-sides. The multi-strip hit fraction showed a clear rotation and magnetic-field dependence. From the angles where the fractions were minimum in the 1T magnetic field, the Hall mobilities of the electrons and holes were obtained to be 1391k43 (clcctrons) and 325f30 (holes) cm2/Vs.
14887208
Beam tests of a double-sided silicon strip detector with fast binary readout electronics before and after proton-irradiation
Abstract A double-sided silicon strip detector with a radiation-tolerant design was fabricated and characterized in a sequence of beam tests at KEK using 4 GeV/ c pions. The detectors were combined with newly designed, fast, lower power, bipolar amplifier-shaper-discriminator chips and CMOS digital pipeline chips to record hit-no hit signals in the strips. Efficiencies, noise occupancies, and spatial resolutions were measured before and after the proton irradiation at an equivalent fluence of 1 × 10 14 p/cm 2 , depending on angle of track incidence and strip-pitches. The median pulse height distribution, derived from the threshold scans of the efficiency, allowed to extract the response of the detector. A 1 T magnetic field enabled us to determine the Hall mobilities of electrons and holes.
120531581
A high resolution holographic freon bubble chamber for the Fermilab high energy neutrino experiment
Abstract A high resolution holographic freon bubble chamber has been constructed for a high energy neutrino experiment at Fermilab. The chamber has a volume of 1150 l filled with a heavy liquid (freon) and has high resolution holographic optics. A muon detector system has been installed to measure high energy muons scattered from the neutrino interactions. Some systematic studies have been done to optimize bubble chamber operation with holographic photography. Results of these studies are presented along with a description of the hybrid bubble chamber system.