Some practical data on the first Townsend coefficient of organic vapour in avalanche counters

The purpose of this investigation is the optimal use of Townsendʹs formula αp = A exp[−B(Kp)] for the estimation of the gas amplification of avalanche counters. The gas constants, A and B, were determined by the parallel-plate avalanche counter (PPAC) method (Sernicki, Nucl. Instr. and Meth. A 288 (1990) 555), implemented at pressures (p) successively increasing by 1 Torr. PPACs, filled with n-heptane vapour, were used. The optimal solution was chosen from the three very precisely determined (at different boundary conditions) variants of data on the first Townsend coefficient (α) of n-heptane in PPAC detectors. The chosen one is justifiable in the range of reduced electric field intensity (Kp) values from 172.2 to 940 V/cm Torr, which includes the largest spans of applicable PPAC operating voltages. The results obtained were compared with the authorʹs previous solutions (Sernicki, Nucl. Instr. and Meth. A 288 (1990) 555; Sernicki, Nukleonika 40 (4) (1995) 67).