We have developed a new imaging device consisting of a VUV scintillator coupled to a gas photomultiplier (gas PMT) with a CsI photocathode, micro pixel chamber (μ-PIC) and gas electron multipliers (GEMs). Generally, the VUV scintillator has a short decay time of less than ∼ 10 nsec. Thus the new detector could be used under the high rate counting ( ∼ 10 MHz) in the hard X-ray to soft-gamma ray region. Our goal in this paper is to obtain a soft gamma-ray image at 0.1 MeV with our gas PMT combined with the VUV scintillator as a high rate counter, and we have optimized electric fields in the gas PMT and developed a new VUV scintillator with a higher light output. In order to obtain a higher collection efficiency of photoelectrons and suppress the ion feedback in the gas PMT, we first optimized the electric field. Then we decided the electric field in the drift, transfer, and induction region to be 0.25, 1.0 and 3.0 kV/cm, respectively. The total gas gain of the gas PMT was approximately 2 × 105, and the gas PMT was estimated to have a quantum efficiency (QE) of 0.7% at 178nm. Additionally, as a consequence of new VUV scintillators search, Nd:LuLiF4 and Nd:LuF3 with a volume of 10mm × 10mm × 5mm were found to have higher light outputs than Nd:LaF3, which is a conventional VUV scintillator, by a factor of 2.1, and 2.6, respectively, and the Nd:LuF3 irradiated with 5.5-MeV alpha-rays had a light output of approximately 400 photons. Finally, we succeeded in obtaining the crystal images upon 5.5MeV alpha and 0.122MeV gamma rays excitation from 241Am- and 57Co sources, respectively, using the gas PMT with the Nd:LuF3.
- Micropattern gaseous detectors (MSGC, GEM, THGEM, RETHGEM, MHSP, MICROPIC, MICROMEGAS, InGrid, etc)
- Photon detectors for UV, visible and IR photons (gas)
- Photon detectors for UV, visible and IR photons (gas) (gas-photocathodes, solid-photocathodes)
- Scintillators, scintillation and light emission processes (solid, gas and liquid scintillators)
ASJC Scopus subject areas
- Mathematical Physics