MPGD for breast cancer prevention: a high resolution and low dose radiation medical imaging

This paper presents an investigation of the discharge propagation (DP) to the readout electrode that occurs with a microsecond time delay after a primary discharge that develops inside a GEM foil hole. A single hole THGEM (THick GEM) foil that enables a controlled discharge position and the induction of primary discharge with an over-voltage in the THGEM foil has been used in the initial DP measurements. In order to justify the use of a custom-made THGEM foil, additional measurements were made with a standard GEM foil. Correlated optical (with an ordinary SLR and a high-speed camera) and electrical measurements of the delayed DP were made for Ne-CO 2 -N 2 (90-10-5) mixture and with different powering configurations. Measurements show that the delayed DP happens without a drift field, with an inverted induction field, inverted THGEM voltages or an inverted drift field. After the primary discharge, there is a charge transfer in the induction region at an induction field value below that of the onset field for DP. In the time between the primary discharge and the delayed DP, three different current regimes are observed, which suggests multiple charge transfer mechanisms in the induction region. High-speed camera recordings provide valuable insight into the time evolution of the primary and the delayed DP, especially when correlated with electrical measurements.

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“…They have a broad field of usage other than in physics, such as medicine or homeland security. [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Studies of the delayed discharge propagation in the Gas Electron Multiplier (GEM)

Utrobicic

Kovačić

Erhardt

et al. 2019

Nuclear Instruments and Methods in Physics Research Section A:

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“…Depending on these applications, detectors have to fulfill requirements of sensitivity, spatial and temporal resolution and accuracy in addition to radiation hardness, material budget limits and other technical constraints. Relying on state-of-the-art manufacturing techniques, MicroPattern Gaseous Detectors (MPGDs) are able to meet the most stringent requirements of high energy physics experiments [1] and have also achieved popularity in medical imaging [2,3] and neutron detection and beam monitoring [4,5]. After converting incident radiation to primary electrons through ionization of the gas in a drift volume acting as active target, MPGDs employ high electric field regions to achieve high charge multiplication factors in electron avalanche processes.…”

Section: Introductionmentioning

confidence: 99%