Akira Konaka

Measurements of the electron drift velocity and positive-ion mobility for gases containing CF4

Abstract Measurements of the electron drift velocity and positive-ion mobility for gases containing CF 4 have been performed. The results are presented for four types of gas mixtures containing CF 4 and hydrocarbons: CF 4 +CH 4 , CF 4 +C 2 H 6 , CF 4 +C 3 H 8 and CF 4 +iso-C 4 H 10 . To make a comparison, also positive-ion mobilities for Ar+C 2 H 6 and Ar+C 3 H 8 gas mixtures have been measured. The drift velocities of electrons in a few mixtures are found to exceed 10 cm/μs, twice that in a conventional drift chamber gas such as Ar(50%)+C 2 H 6 (50%). In particular, the electron drift velocity in CF 4 (10%)+CH 4 (90%) is larger than 10 cm/μs, even at a reduced electric field E / P of more than 1 V/(cm Torr). Results on the measurements of the positive ion mobility are consistent with the interpretation that the hydrocarbon ions are the positive ions eventually drifting toward the cathode in the studied gas mixtures. Their mobilities in CF 4 are found to be smaller than those in Ar.

Test of BaF2 scintillators coupled to a photomultiplier with a CsTe photocathode

Basic properties of BaF2 scintillators coupled to a photomultiplier with a CsTe photocathode have been investigated. The signal from the photomultiplier shows a drastic reduction of the slow component of the BaF2 scintillation light while preserving the good properties associated with the fast component.

Plastic scintillating fibers for track detection

A particle track detector consisting of plastic scintillating fibers and a gatable image intensifier system has been developed and tested with pion, proton and deuteron beams of 1 GeV/c. We have observed clear tracks of beams and scattered particles at a beam rate of up to 105 particles per second. Tracks have been recorded by using a CCD video camera at a trigger rate of around 30 Hz. The energy and spatial resolutions have been investigated.