Speaker
Joao F.C.A. Veloso
(Uni Aveiro)
Description
We present a Photon-Assisted Cascaded Electron Multipliers (PACEM) which
has a potential for ion back-flow blocking in gaseous radiation detectors: the
avalanche from a first multiplication stage propagates to the successive one
via its photons, which in turn induce photoelectron emission from a
photocathode deposited on the second multiplier stage; the multiplication
process may further continue via electron-avalanche propagation. The
photon mediated stage allows, by a proper choice of geometry and fields,
complete blocking of the ion back-flow into the first element; thus, only ions
from the latter will flow back to the drift region. The PACEM concept was
validated in a doubleMHSP (Micro-Hole & Strip Plate) cascaded multiplier
operated in xenon, where the intermediate scintillation stage provided
optical gain of ∼ 60. The double-MHSP detector had a total gain above 10 4
and energy resolution of 18% FWHM for 5.9 keV x-rays. Systematic studies
of this detector concept for ion back flow and optical gain as a function of the
voltages applied in the different electrodes will be presented.
Author
Joao F.C.A. Veloso
(Uni Aveiro)
