Thick silicon strip detector Compton imager

We present results obtained with double-sided, thick (2 mm) silicon strip detectors used as a Compton imager. Reconstructed images and spectra from ¹³⁷Cs and ⁶⁰Co gamma-ray sources have been produced at room temperature using the multiple Compton technique. Multiple Compton interactions allow the energy and Compton scattering angle to be reconstructed without having to absorb the energy of the incident gamma ray completely. This extends our work on multiple Compton imagers using germanium strip detectors to silicon detectors that operate at higher temperatures. The energy resolution of the detectors for 60 keV gamma rays is 3-4 keV at room temperature and 2.1 keV at -20°C. Simulations of the imager have been performed in GEANT4, including Doppler broadening and accidental coincidences, and show agreement with the measured data. Reconstructing the energy spectrum for 662 keV gamma rays that did not deposit their full energy in the instrument shows a peak at 662 keV with a full-width at half-maximum (FWHM) of 27.6 keV. The reconstructed image of the source shows an angular resolution of 3.3° FWHM.