Enhanced electron transfer in Penning gases

We present the discovery of the enhanced transfer of electrons produced in avalanches through metal grids in Penning gas mixtures.

Measurements are presented showing the enhancement which is particularly dramatic at very low transfer fields. With electric fields on either side of the grid in the ratio of 0.015 the transfer ratio is 0.11, representing an increase of a factor of 7 over that predicted and observed in a conventional gas by Bunemann et al. [1]

We propose a model for this phenomenon and we show that both a uniform electric field and the Penning effect [2] are necessary for this transfer to occur. We also identify a possible reason why other workers have not obtained similar results in Penning mixtures.

The application of this “Penning transfer” to a position sensitive X-ray detector (the Penning Gas Imager or PGI [3]) is discussed.