Compton camera coincidences in the silicon drift detector

Abstract

A Compton camera system consisting of a silicon drift detector (SDD) and an Anger camera has been constructed to study coincidence events and the possibility of tracking a recoil electron. An event is considered as a coincidence when a photon emitted from a radioactive source is first Compton scattered in the SDD where the recoil electron deposits its energy and the scattered photon undergoes a photoelectric absorption in the NaI(Tl) crystal of the Anger camera. SDD is composed of a monolithic array of 19 cells each having an on-chip transistor which provides the first stage amplification. 137 Cs source has been finely collimated in order to study events occuring at different locations within a single cell. Electron tracks depositing energy in multiple cells have also been studied by considering time coincidences between SDD cells and the Anger camera. The equipment is designed such that the measurements can be done in all detector orientations and kinematical conditions. The angular and energy distribution of coincidence events have been studied with high statistics. Energy resolution and angle measurements performed with this detector system will be presented in this paper.

Detective Quantum Efficiency and Deadtime Losses in Compton Imaging Systems

“…The time-stamping plays a central role in the DAQ system, where asynchronously detected signals of detector components are synchronized for further processing. With this system, the signals created by Compton electrons in the silicon drift detector and the signals of the scattered photons detected in time coincidence at the absorption detector and the incoming gamma ray from the source could be coupled and the scattering events could be reconstructed, where an angular resolution of 1 • [5,6], that is close to the theoretically expected value, could be achieved.…”