Transverse Matching Techniques for the SNS Linac

It is crucial to minimize beam loss and machine activation by establishing optimal transverse matching for high intensity linear accelerator such as the Spallation Neutron Source linac. For matching DTL to CCL, there are four wire-scanners installed in series in CCL module 1 as proposed in [1]. A series of measurements was conducted to minimize envelope breathing and the results are presented here. As an independent approach, Chu et al is developing an application based on another technique by estimating rms emittance using the wire scanner profile data [2]. For matching MEBT to DTL, a technique of minimizing rms emittance was used and emittance data show that tail is minimized as well.

INTRODUCTION

The Spallation Neutron Source (SNS) accelerator system is designed to accelerate intense proton beams to energy of 1-GeV, delivering more than 1.4 MW (upgradeable to 2 MW) of beam power to the neutron production target [3]. Being a high intensity linac, a primary concern is potential damage and radio activation of accelerator components resulting from uncontrolled beam losses. A major source of loss is beam halo that intercepts the bore of the linac. It is important to accomplish adequate level of transverse matching between sections of linac.