Evaluation of a High-Power Target Design for Positron Production at CEBAF

TL;DR

This paper evaluates a high-power tungsten target design for polarized positron production at CEBAF, analyzing thermal, mechanical, and radiation damage aspects to optimize the target's performance and durability.

Contribution

It introduces a novel rotating tungsten rim target design and provides detailed thermal, mechanical, and radiation damage analyses for high-power positron sources.

Findings

Rotating tungsten rim effectively manages heat load.

Thermal and mechanical analyses ensure target durability.

Radiation damage assessments inform target lifespan.

Abstract

A source for polarized positron beams at the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab is being designed. The Polarized Electrons for Polarized Positrons (PEPPo) concept is used to produce polarized e$^+$e$^-$-pairs from the bremsstrahlung radiation of a longitudinally polarized electron beam interacting within a high-$Z$ conversion target. The scheme under consideration includes a 4 mm thick tungsten target that absorbs 17 kW deposited by a 1 mA continuous-wave electron beam with an energy of 120 MeV. The concept of a rotating tungsten rim mounted on a water-cooled copper disk was explored. The results of ANSYS thermal and mechanical analyses are discussed together with FLUKA evaluations of the radiation damages.