Kiyoshi Kubo

Feasibility of optical diffraction radiation for a non-invasive low-emittance beam diagnostics

Abstract A “proof-of-principle” experiment on the optical diffraction radiation (ODR) as a single-pulse beam profile monitor is planned using an electron beam extracted from the KEK-ATF damping ring. The main goals of this experiment are the following: (i) To measure the yield and the angular distributions of the optical diffraction radiation from a large-size target at different wavelengths, impact parameters and beam characteristics for a comparison with analogous characteristics of optical transition radiation from a foil with identical optical parameters and for a verification of the model assumption (perfectly conducting semi-infinite target). (ii) To investigate the ODR angular distributions from a tilted target with a slit for observing the interference effects. (iii) To compare the results obtained by simulations based on classical approaches, taking into account the optical characteristics of the equipment and the beam parameters. (iv) To estimate the prospects of using ODR as a new non-invasive tool for ultrarelativistic beams. We estimated that the ODR photon yield in 10% bandwidth for 500 nm is about 106 photons/bunch with an impact parameter of 100 μm . This indicates that the ODR monitor is a promising candidate for single-pulse beam-profile measurements, and that it will be an extremely useful instrument for future linear colliders (JLC, NLC, TESLA and CLIC).

Time-of-Flight Counters for VENUS Detector

A time-of-flight counter system has been installed in the VENUS detector of the TRISTAN experiment at KEK. A time resolution of about 200 ps was obtained for a long scintillator of 466 cm. The system is being successfully operated in experiments.

Beam-based alignment at the KEK-ATF damping ring

The damping rings of a future linear collider will have demanding alignment and stability requirements in order to achieve the low vertical emittance necessary for high luminosity. The Accelerator Test Facility (ATF) at KEK has successfully demonstrated the vertical emittance below 5 pm that is specified for the GLC/NLC Main Damping Rings. One contribution to this accomplishment has been the use of Beam Based Alignment (BBA) techniques. The mode of operation of the ATF presents particular challenges for BBA, and we describe here how we have deduced the offsets of the BPMs with respect to the quadrupoles. We also discuss a technique that allows for direct measurements of the beam-to-quad offsets.

Intrabeam scattering analysis of measurements at KEK’s Accelerator Test Facility damping ring

We derive a simple relation for estimating the relative emittance growth in

ATF extraction line laser-wire system

x

Beam test of multi-bunch energy compensation system in the accelerator test facility at KEK

and

Intrabeam scattering analysis of ATF beam measurements

y

Long term performance of the TRISTAN superconducting RF cavities

due to intrabeam scattering (IBS) in electron storage rings. We show that IBS calculations for the Accelerator Test Facility (ATF) damping ring, when using the formalism of Bjorken-Mtingwa, a modified formalism of Piwinski (where

The vertical emittance in the ATF damping ring

{\ensuremath{\eta}}^{2}/\ensuremath{\beta}

X-band accelerating structure for Japan Linear Collider

has been replaced by