The scintillating fiber camera is a type of three-dimensional track detector. Using this camera, we can observe the scintillation track produced along the path of a charged particle, and from its scintillation yield can determine the linear energy transfer (LET) distribution of the charged particle. Such observations are also possible for recoil (charged) particles produced by fast neutrons. From these data, we can estimate the LET distribution of individual charged particles or that of recoil particles produced by neutrons; and finally, we can estimate the dose equivalent due to charged particles and/or fast neutrons. For use as a dosimeter for fast neutrons produced by the interaction between cosmic-ray particles and wall materials of a manned spaceship in space, a 52 mm cubic scintillating fiber camera with a 75 mmΦ gated-image intensifier with a maximum counting rate of 30 Hz was constructed. The dosimeter consists of a stack of scintillation fibers with a sensitive volume of 52 mm × 52 mm × 52 mm and a 75 mm diameter image intensifier for readout from the scintillation fibers. The scintillation yields were measured for high-energy heavy ions such as carbon and argon ions. An energy resolution of 12% full-width half-maximum (FWHM) was obtained for penetrated argon ions of 650 MeV/n. These results demonstrate that this type detector is very useful as a dosimeter for high-energy cosmic rays and their secondary neutrons.
Image intensifiers are routinely used for fast optical shuttering (into the sub-nanosecond region) and for photon counting for extended weak images. For many applications needing a large image input size, it has become common practice to use a fibre optic taper coupled to a CCD. The high quantum efficiency of the CCD is degraded by the optical losses in the fibre taper which may only be a few percent transmission. This had led Photek into developing ever-larger image intensifiers, 75 mm tubes in 1992, 80 mm in 1996, and 150 mm in 1999. This paper gives the results obtained with a 150 mm photon counting prototype tube. Results of photocathode developments and fast gating of these large tubes are also presented, together with anticipated performance of even larger proximity focus tubes. These tubes offer significant performance enhancement compared to fibre taper systems for most applications needing large image input format.
Microchannel plate photomultipliers (MCP-PMTs) are commonly used for single photon counting fluorescence decay measurements. Recent developments to improve the pulse height distribution are described. This enables the tube to be better matched to amplifiers, constant fraction discriminators and the ensuing electronics. Multi-anode tubes are also produced for multi-channel spectroscopy. Recent measurements of crosstalk in such tubes are presented and discussed.
Conference Committee Involvement (2)
Vacuum and Solid State Photoelectronic Imagers, Detectors, and Systems II
5 August 2004 | Denver, Colorado, United States
Vacuum and Solid State Photoelectronic Imagers, Detectors, and Systems