JINST Instrumentation Theses Archive

Ph.D. degree thesis
accepted by Weizmann Insitute of Science, Israel, in 2009

Alexey Lyashenko

Supervisor: Prof. Amos Breskin

Development of gas-avalanche photomultipliers sensitive in the visible spectral range

 Keywords:

• Avalanche-induced secondary effects
• Gaseous detectors
• Micropattern gaseous detectors (MSGC, GEM, THGEM, RETHGEM, MICROMEGAS, InGrid, etc)
• Photon detectors for UV, visible and IR photons (gas)

 Abstract:
The aim of the present research was the development of novel gaseous-photomultiplier (GPM) concepts for the visible spectral range. The goal was to conceive novel state-of-the-art gas-avalanche electron multipliers coupled to thin-film bi-alkali photocathodes, capable of high-gain stable long-term operation in continuous-mode. The main difficulties were blocking of avalanche-ions and the stability of the highly-sensitive UV-to-visible photocathodes under gas avalanche multiplication.
During this research, the following points were thoroughly investigated: R&D on novel gaseous electron multipliers, Production and characterization of various alkali photocathodes, Ion back-flow reduction in cascaded gaseous multipliers, Photocathode ageing under the ion bombardment, Ion-induced secondary electron emission from bi-alkali photocathodes, Gaseous photon detectors assembly and operation
The most significant results obtained are: A cascaded electron-multiplier structure with unprecedentedly reduced back-flow of avalanche ions to the photocathode permitted for the first time a stable high-gain, continuous-mode operation of a gaseous photomultiplier coupled to a visible-sensitive K2CsSb photocathode.