Publisher Summary This chapter presents a survey of previous works in related fields, coupled with current experience in the environmental scanning electron microscope (ESEM). This microscope allows the examination of specimens in the presence of a gaseous environment. The scintillation produced by various signals can also be used for making images, and a generalized gaseous detector device (GDD) was proposed. GDD is based on the principle of classical gaseous particle detectors adapted to the specific requirements of the ESEM. The chapter presents an account of the new terminology associated with ESEM. Physical principles for the analysis of ESEM are electron and ion temperature, imaging parameters, theory of induced signal, and induced signals in the ESEM. Whereas, the physical parameters involved in the performance of the GDD are electron and ion mobilities, diffusion, recombination, electron attachment, and effective ionization energy. The chapter outlines the discharge characteristics and accounts for amplification, parallel plates; the first Townsend coefficient; the Paschen law; and secondary processes. The ESEM is a radiation source immersed inside a gas, and, therefore, the methods of nuclear and particle physics for spectroscopic analysis can be applied. Principles of spectroscopy including spectroscopy, statistics, and energy resolution and environmental scanning transmission electron microscopy are discussed. The chapter focusses on mechanisms of a high gaseous gain.

Theory of the Gaseous Detector Device in the Environmental Scanning Electron Microscope

Improved resolution for low energies with gas proportional scintillation counters.

A high pressure gas self-triggered scintillation drift chamber has been built with a working volume of 30 cm diameter and 4 cm depth, viewed through glass windows by an array of 19 PMTs. The detector tested at 9 bar xenon filling showed 2.7% FWHM energy resolution at 122 keV over a 22 cm field of view and three-dimensional sensitivity with X , Y resolution of 3.7 mm FWHM and Z resolution of 0.6 mm FWHM for 60 keV photoabsorbed γ-rays. The readout system of the detector is able to select multi-vertex events occurring in the sensitive volume due to γ-ray absorption and discriminate fluorescent photons, Compton scattering and photoabsorption vertices. The energy resolution in “fluorescent photon gated mode” has been measured as 2.2% FWHM at 122 keV γ-ray. Some possible applications of the detector are discussed.

A high pressure xenon self-triggered scintillation drift chamber with 3d sensitivity in the range of 20-140 kev deposited energy

Data an the xenon uniform field gas proportional scintillation counter is presented. The energy resolution obtained for 8.1 MeV ?-particles was 1.2%. Measurements for pressures from 600 to 1500 Torr showed that the "reduced light output", i. e. the number of photons produced by a single electron travelling the unit of distance, divided by the gas pressure, depends only on the reduced electric field but not on the gas pressure. An empirical equation for this quantity is given. The role played by different mechanisms is discussed.

/pdf/the-secondary-scintillation-output-of-xenon-in-a-uniform-4gibnhwrc5.pdf

C.A.N. Conde

Papers

The argon-nitrogen proportional scintillation counter

Large light output gas proportional scintillation counters

The argon uniform-field gas proportional scintillation counter: Improved energy resolution for α-particles and its behaviour for X-rays☆

The gas proportional scintillation counter: Evaluation of performances with interest for analysis by ion beam techniques