Problems in the Design of Cryogenic Target Facilities for Electron Scattering Experiments

Abstract

This paper describes a proposed target facility for use in a program of electron scattering experiments at the Naval Research Laboratory electron linear accelerator on inelastic electron scattering experiments on low atomic number elements as H1, H2, H3, He3 and He4, all of which in the liquid or solid state provide compact, high density, well localized, targets of pure elements. Problems discussed are: (a) electron energy dissipation in cryogenic targets by continuous electron beams of 5-60 MeV energy, (b) target design dimensions such as target diameter to beam diameter ratios, permitting maximum incident beam current, (c) treatment of pulsed electron beams using "instantaneous line source theory" in estimation of maximum permissible current densities, (d) vapor production and mechanical shock in targets based in part on bubble chamber theory, and (e) thermal radiation into the target shields from the scattering chamber wall.