Development of a Compton imager based on bars of scintillator

TL;DR

This paper presents a compact, large field-of-view Compton gamma-ray imager using scintillator bars, capable of quickly localizing sources in the 392 keV to 1274 keV range with high angular resolution.

Contribution

The development of a low-channel-count, fast, and portable Compton imager based on scintillator bars with demonstrated effective localization and angular resolution.

Findings

Angular resolution of 2.72 degrees at 662 keV

Localization of a 10 mCi Cs-137 source at 40 meters in 60 seconds

Stable imaging performance up to 40 degrees off-axis

Abstract

We have developed a compact Compton gamma-ray imager with a large field of view and a low channel-count that is capable of quickly localizing gamma-ray sources in the few hundred keV - several MeV range. The two detector planes (scatter and absorber) employ bars of NaI(Tl) read out by photomultiplier tubes (PMTs) located at each end. The long-range imaging performance has been tested from 392 keV to 1274 keV. An angular resolution measure of 2.72 +/- 0.06 degrees and an efficiency of (1.79 +/- 0.04) x 10^(-3) at 662 keV is obtained. A Cs-137 (662 keV) source equivalent to a 10 mCi source 40 m away can be located in 60 seconds with an uncertainty of about a degree. No significant degradation in imaging performance is observed for source angles up to 40 degrees off axis.