| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1994: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1993: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
The self-quenching streamer (SQS) mode of gas counter operation is a basically important operation mode as well as the established ionization-chamber, proportional, and GM modes. The SQS mode indicates a very high gas multiplication, and furthemore very good counting rate characteristics that are superior to the GM mode by about one order. In the present pfoject, the mechanism of the SQS mode, in which the photoionization process may be important, was investigated by means of UV-laser light.
The results are summarized as follows :
1) The counting rate characteristics of SQS tubes are improved by adding the second quenching gas vapor such as methylal to usually used counting gas mixture of Ar-isoC_4H_<10>. It encourages us to use SQS tubes in high radiation dose field near reactor sites.
2) The mechanism of SQS produced by alpha-rays was revealed by optical observation of streamers with image intensifiers. Since two streamers are generated by electrons that come from ionization tracks by alpha-rays, high electron-density ionization-tracks accelerate the SQS transition.
3) The SQS transition is observed by means of UV-laser light, Size of electron avalanches depends on the laser power and the ionization proceeds through the multiple photo-absorption process. The SQS transition is, therefore, similar to those by charged particles such as alpha-rays.
4) The contribution from excitation of meta-stable states are not so clear, because the ionization by UV laser light and photoionization are to be identified. It should be studied furthemore.
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