We review the data and models describing the production of the electrons, termed secondary electrons, that initiate the secondary and subsequent feedback avalanches required for the growth of current during breakdown and for the maintenance of low-current, cold-cathode discharges in argon First we correlate measurements of the production of secondary electrons at metallic cathodes, ie the yields of electrons induced by Ar+ ions, fast Ar atoms, metastable atoms and vuv photons The yields of electrons per ion, fast atom and photon vary greatly with particle energy and surface condition Then models of electron, ion, fast atom, excited atom and photon transport and kinetics are fitted to electrical-breakdown and low-current, discharge-maintenance data to determine the contributions of various cathode-directed species to the secondary electron production Our model explains measured breakdown and low-current discharge voltages for Ar over a very wide range of electric field to gas density ratios E/n, ie 15 Td to 100 kTd We review corrections for nonequilibrium electron motion near the cathode that apply to our local-field model of these discharges Analytic expressions for the cross sections and reaction coefficients used by this and related models are summarized

https://iopscience.iop.org/article/10.1088/0963-0252/8/3/201/pdf

Cold-cathode discharges and breakdown in argon: surface and gas phase production of secondary electrons

Introduced by the author in 1997, The Gas Electron Multiplier (GEM) constitutes a powerful addition to the family of fast radiation detectors; originally developed for particle physics experiments, the device and has spawned a large number of developments and applications; a web search yields more than 400 articles on the subject. This note is an attempt to summarize the status of the design, developments and applications of the new detector.

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The gas electron multiplier (GEM): Operating principles and applications

We review the current status of liquid noble gas radiation detectors with energy threshold in the keV range, which are of interest for direct dark matter searches, measurement of coherent neutrino scattering and other low energy particle physics experiments. Emphasis is given to the operation principles and the most important instrumentation aspects of these detectors, principally of those operated in the double-phase mode. Recent technological advances and relevant developments in photon detection and charge readout are discussed in the context of their applicability to those experiments.

Liquid noble gas detectors for low energy particle physics

CsI films are known to be efficient photoconvertors, intensively investigated for UV-photon imaging devices. The article reviews the production and characterization techniques of CsI photocathodes and their photoemission properties in vacuum and gas media, in charge collection and multiplication modes. The important roles of surface phenomena, gas and electric fields are described. The stability of the films is discussed.

/pdf/csi-uv-photocathodes-history-and-mystery-5gkap1vp1r.pdf

CsI UV photocathodes: history and mystery

SUMMARY

The environmental scanning electron microscope (ESEM) allows the examination of specimens in a gaseous environment. It is based on an integration of efficient differential pumping with a new design of electron optics and detection systems. Backscattered, cathodoluminescence and X-ray detectors can be designed to fit and to perform optimally in the ESEM. The secondary electron signal can be detected with the gaseous detector device, which is a new multipurpose detector. Insulating, uncoated, wet and generally both treated or untreated specimens can be studied.

Review and outline of environmental SEM at present

Improved resolution for low energies with gas proportional scintillation counters.

A gas proportional scintillation counter

Gaseous media may efficiently convert into photons the energy losses of particles and the energy supplied by electric fields to drifting electrons. Some mechanisms associated with the process of light production, in particular the two continua and a few energy transfer phenomena, are considered. The relevance of these processes to control the spectral distribution of the photons, and consequently to its detection, and their interest for the time characteristics and the energy resolution capabilities of detecting devices are also referred to. A few examples are presented of instrumental results that either reflect important characteristics of gas scintillation counters, or point to further possible developments, as regards energy, time and position resolutions.

Light Production and Gaseous Detectors

We report on the optical readout of the gas electron multiplier (GEM) operated with a gaseous mixture suitable for the detection of thermal neutrons: 3 He–CF4. A CCD system operating in the 400–1000 nm band was used to collect the light. Spectroscopic data on the visible and NIR scintillation of He–CF4 are presented. Images of the tracks of the proton and triton recorded with a triple GEM detector are also shown. r 2002 Elsevier Science B.V. All rights reserved. PACS: 29.40.Gx

/pdf/ccd-readout-of-gem-based-neutron-detectors-27hs5kp4we.pdf

A.J.P.L. Policarpo

Papers

Improved resolution for low energies with gas proportional scintillation counters.

A gas proportional scintillation counter

Light Production and Gaseous Detectors

CCD readout of GEM-based neutron detectors

The argon-nitrogen proportional scintillation counter