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Origins
Published in Douglas S. McGregor, J. Kenneth Shultis, Radiation Detection, 2020
Douglas S. McGregor, J. Kenneth Shultis
A timeline of the major developments in radiation detector inventions is shown in Figs. 1.16 and 1.17. This chart provides a snapshot up through 2010. However, this is not the end of detector history. Detector development actively continues today and the discipline is far from being exhausted, as evidenced by many new devices and designs produced in the past two decades. Novel approaches and designs, such as the gas electron multiplier (GEM), have expanded the use of gas-filled detectors. New scintillation materials, such as various lanthanide halides and elpasolites, have been developed that offer gamma-ray energy resolution that is much better than NaI:Tl. Also, new compact photomultiplier devices based on semiconductors have become available. Clever semiconductor detector designs have significantly reduced the effects of defects previously impeding progress with compound semiconductor detectors. Novel detector approaches using cryogenics have yielded devices with unprecedented energy resolution. Micro-machined semiconductors have produced the first high-efficiency semiconductor neutron detectors. All of these devices, amongst a myriad of other designs and technologies, some still in development, are described in chapters throughout this text.
Importance of Genetically Engineered Microbes (GEMs) in Bioremediation of Environmental Pollutants
Published in Vineet Kumar, Vinod Kumar Garg, Sunil Kumar, Jayanta Kumar Biswas, Omics for Environmental Engineering and Microbiology Systems, 2023
Wilgince Apollon, Héctor Flores-Breceda, Gerardo Méndez-Zamora, Juan Florencio Gómez-Leyva, Alejandro Isabel Luna-Maldonado, Sathish-Kumar Kamaraj
This indicates that molecular methods are promising because they allow the cultivation of microbes with a high bioremediation capacity. The development of GEMs through genetic engineering has been a great achievement because these organisms are more efficient compared to native microbes. Brockman (1995) demonstrated that a combination of traditional methods with novel molecular methods results in a more robust method of efficient quantification of GEMs, which will have positive effects on the natural microbial population. GEM production and release methods must be (1) very efficient and (2) highly sensitive where there is a low number of GEMs present in the sample.
Simulation study of ternary gas mixture transport properties and their gain in GEM detectors used for muon tracking
Published in Molecular Physics, 2022
Badria Al Rashdia, Amr Radi, Abbasher Gismelseed, Ahmed Al Rawas
One of the four main experiments at the Large Hadron Collider (LHC) is Compact Muon Solenoid (CMS) [1]. The muon system at CMS has different types of detectors that are used for tracking and triggering purposes. GEM has been proposed to be installed at the high η region of the muon detection system of CMS endcap because it has a high capability to work in that region which is exposed to high flux of radiation [2–7]. Fabio Sauli introduced GEM in 1997 at CERN [8]. The operational principle of a GEM detector is based on gas ionisation. Usually, the gas used consists of noble gas like Ar, Xe, and He with some quenchers like CO2, iC4H10, and CH4. The gas mixtures that are used in GEM detectors in CMS experiments are Ar/CO2 with ratios of 70/30 [9]. Although this second mixture is faster, which is convenient for triggering, it is environmentally hazardous [10] and needs to be treated with caution [11]. So, in order to find a freon-free method that can also increase muon detection performance, this research was carried out. Besides that, the study focuses on ternary gas mixtures since many studies have been done on binary ones [12–16]. In this work, the transport properties of gas mixtures that have first an inert gas (Ar-He-Xe-Ne), second a quencher gas (CO2), and a third gas (N2, CH4, iC4H10, C5H12) with different proportions are studied. Ar/CO2 (70/30) is used as a reference to compare the results. Although this study is aimed at GEM detectors, its findings can be useful to other gaseous detectors as well.
Characterization of three GEM chambers for the SBS front tracker at JLab Hall A
Published in Radiation Effects and Defects in Solids, 2018
L. Re, V. Bellini, V. Brio, E. Cisbani, S. Colilli, F. Giuliani, A. Grimaldi, F. Librizzi, M. Lucentini, F. Mammoliti, P. Musico, F. Noto, R. Perrino, C. Petta, M. Russo, M. Salemi, F. Santavenere, G. Sava, D. Sciliberto, A. Spurio, M.C. Sutera, F. Tortorici
The simplest gas detector of the GEM technology is the single GEM chamber, which consists of one GEM foil to which a voltage is applied and which is sandwiched between two flat parallel electrodes, where the anode is a read-out plane made up of strips or pads. We give a schematic cross-section view of a single GEM detector in Figure 2.