| NUKLEONIKA 1995, 40(4):67-88
ON USING THE TOWNSEND'S a/p FORMULA FOR THE ESTIMATION
OF GAS AMPLIFICATION
OF AVALANCHE COUNTERS
J. Sernicki
Department of Nuclear Spectroscopy, Soltan Institute for Nuclear Studies,
05-400 Otwock-Œwierk, Poland
The object of investigation was to clear-up whether or not the formula a/p =
A exp [-B/(K/p)] is capable of describing the first Townsend coefficient (a) of
organic vapour in PPAC detectors by a single pair of gas constants A, B only. Basing upon
the data obtained according to author's implementation of the PPAC method with parallel-plate avalanche
counters (PPAC) operated at n-heptane pressures p >= 5 Torr
and having an electrode spacing d from 0.1 to 0.4 cm, the author determines the constants, now
under ultimate criteria. Both constants exhibit an explicit dependence upon the spacing d. It
appears that the veracity of A and B does not depend upon d within the interval of
263.9-355.9 V/cm·Torr (reduced electric field intensity (K/p) values) only. In view of
both, the present results as well as the earlier investigation carried out at reasonable criteria,
the common applicability of the Townsend's formula remains disputable.
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