A fast detector for single-shot positron annihilation lifetime spectroscopy

✍ Scribed by D.B. Cassidy; A.P. Mills Jr.

• Book ID: 103856664
• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 190 KB
• Volume: 580
• Category: Article
• ISSN: 0168-9002
• DOI: 10.1016/j.nima.2007.06.078

✦ Synopsis

When an intense sub-nanosecond positron pulse impinges upon a target, a pulse of g-rays is created which can yield information concerning electron-positron pairs just prior to annihilation. Many conventional g-ray detectors are unable to exploit the timing information contained within such pulses, and we describe here the development of a fast detector that is able to do so. Using a singlecrystal PbF 2 Cherenkov radiator coupled to a fast photomultiplier tube (PMT), we have produced a detector with a time response of $4 ns (primarily determined by the PMT response), as well as a low-efficiency detector with a sub-nanosecond response. Since 511 keV photons produce very little Cherenkov light, the problem of photomultiplier saturation is mitigated and this detector is therefore well suited to single-shot positron annihilation lifetime spectroscopy (SSPALS) measurements.