Colloquium 8Apr2013

Title

A Positron Production Efficiency Measurement using the IAC’S High Repetition Rate LINAC

Abstract

The positron production efficiency of a Linac based positron source that uses on a quadrupole triplet system to collect positrons was measured. Positrons are produced when a 2mm thick tungsten target is impinged by 12 MeV electrons from the High Repetition Rate Linac (HRRL) at Idaho State University's (ISU) Idaho Accelerator Center (IAC). Producing a positron beam in this manner is challenging due to the wide momentum and angular spread of the positrons leaving the downstream side of the tungsten target. Positrons with energies between one to five MeV were observed experimentally after the beam line's 90 degree bend. Positrons that annihilated on a second tungsten target, located at the end of the 90 degree beamline, produced 511 keV photons that were observed using NaI detectors. In this talk, the speaker will present the theory of the positron production as well as the experimental setup, procedure, and measured positron production efficiency.