Damage test for International Linear Collider positron generation target at KEKB

M Kuriki,K Saito,M Kikuchi,T Kamitani,T Mimashi

doi:10.1103/physrevstab.9.071001

Abstract

ILC (International Linear Collider) is aiming to conduct electron-positron collisions at 1 TeV center-of-mass energy. One bunch train will contain up to 2800 3.2 nC bunches with a 308 ns bunch spacing or 5600 1.6 nC bunches with a 154 ns spacing. The bunch-train length will be 0.9 ms. Because of this extremely large amount of beam in a train, serious damage to a positron production target driven by 6 GeV incident electron beam is of concern. As the ILC positron source, several different methods have been proposed. The target hardness is a key point concerning the selection. In this article, we report on a test experiment to examine the target hardness by using a stored electron beam in KEKB HER (High Energy Ring). The project name is IPPAK (ILC Positron Project At KEKB). By manipulating the abort kicker, a condition similar to that of the ILC positron production target can be reproduced. The experiment was carried out on June 29 and 30, 2005. The target was seriously damaged under the heaviest condition (KEKB mode), but the damage was less and nothing for those of the ILC mode. Possible impacts to the ILC positron production scheme are also discussed.

Highlights

The ILC (International Linear Collider) [1] is a linear collider project promoted by ICFA (International Committee for Future Accelerators) [2]
In the ILC Positron Project At KEKB (IPPAK) experiment, the stored beam of KEKB High Energy Ring (HER) [8,9] is injected into a test material placed inside the beam dump
An impressive result was that the damage was varied greatly from that of KEKB390, which was completely damaged, to ILC0.7 which was not damaged at all

Summary

INTRODUCTION

The ILC (International Linear Collider) [1] is a linear collider project promoted by ICFA (International Committee for Future Accelerators) [2]. A totally new method to generate a positron beam was proposed by the TESLA collaboration [5] In this method, high-energy gamma rays (up to 26 MeV), generated by a 70 m planar undulator with a 250 GeV electron beam, are injected in the production target, which has a smaller thickness (0.4 radiation length), resulting in less damage. Because it is very hard to implement a 250 GeV electron linac dedicated to positron production, the electron beam before collisions is used to generate high-energy photons This method is, totally new and has never been built. In the ILC Positron Project At KEKB (IPPAK) experiment, the stored beam of KEKB High Energy Ring (HER) [8,9] is injected into a test material placed inside the beam dump. The last purpose is to precisely control the target material position

EXPERIMENTAL MODES

RADIATION SAFETY

EXPERIMENT

THE SURFACE INVESTIGATION

Findings

SUMMARY