D.J. Herbert

First results of scintillator readout with silicon photomultiplier

A new type of silicon device has been realised that has many properties comparable to or better than a conventional PMT (photomultiplier tube). This paper presents the first results of using these devices in place of PMT for the readout of scintillators for eventual application in PET (positron emission tomography). This device, the silicon photomultiplier (SiPM) is effectively an avalanche photodiode operated in Geiger mode. In Geiger-mode detectors, a very large current signal is produced regardless of the size of the input, giving just logical rather than proportional information. However, the SiPM is subdivided into a large number (1500) of microcells that act as independent and virtually identical Geiger-mode photodiodes. The outputs of all these individual microcells are connected so that the total output signal is the sum of the signals from all of the microcells that were fired. In this way proportional information can be obtained. As a consequence of their design, these detectors have potentially very fast timing (<100 ps), high gain (105-106) at low bias voltage (~50 V), a high quantum efficiency (35% at 500 nm), excellent single photoelectron resolution and are cheap to manufacture. Here their characterisation and initial results when used with pulsed LED and scintillator pixels are presented

A small-animal PET design using SiPMs and Anger logic with intrinsic DOI

In this study a miniature, high-resolution detector head for a small-animal PET imaging system that has intrinsic depth of interaction (DOI) information is proposed. The design is hased upon the classic Anger camera principle, i.e. one detector module layer consists of a continuous slab of scintillator, viewed by a new type of compact silicon photodetector. The photodetector is the recently developed Silicon Photomultiplier (SiPM) that as well as being very compact has many other attractive properties: high gain at low bias voltage, excellent single-photoelectron resolution and fast timing. A detector head of 4/spl times/4 cm/sup 2/ in area is proposed, constructed from three module layers of the continuous detector described above. Here, a simulation study is carried out, using the Monte Carlo simulation package GEANT4. The simulation results are used to determine the performance of a single detector head and to optimize the geometry of the detector, resulting in a spatial resolution of up to /spl sim/0.6 mm full-width at half maximum (FWHM).

Novel high resolution detectors for Positron Emission Tomography (PET)

Abstract In this paper we present some recent results we have obtained in the development of detectors for small animal PET and for PEM, based on the use of Position Sensitive PMTS or Hybrid Photo Diodes (HPDs) coupled to crystal matrices. New ideas and future developments are discussed.

Spectroscopic and scintillation performance of Ce:YAP single crystal fibers grown by μ-PD technique

Ce3+ doped YAIO3 (Ce: YAP) is an attractive scintillator that exhibits fast scintillation, high light yield, excellent mechanical and chemical properties, relatively high density and short decay time. For these advantages we focused our attention on growing this material directly in the device-ready shape of fiber with the new technique called micro pulling down (alpha-PD). At the best of our knowledge, this is the first time that Ce:YAP is grown in such a shape with this growth method. The growth progress will be presented together with the structural characterization by X-ray diffraction method to check the mono-crystalline phase and the orientation of the fibers. Absorption, fluorescence, decay time and scintillation performance will also be presented.