THGEM gain calculations using Garfield++: solving discrepancies between simulation and experimental data

Abstract

Abstract:Discrepancies between the measured and simulated gain in Thick Micropatterned gaseous detectors (MPGD), namely THGEM, have been observed by several groups. In order to simulate the electron avalanches and the gain the community relies on the calculations performed in Garfield++, known to produce differences of 2 orders of magnitude in comparison to the experimental data for thick MPGDs.In this work, simulations performed for Ne/5%CH 4 , Ar/5%CH 4 and Ar/30%CO 2 mixtures shows that Garfield++ is able to perfectly describe the experimental data if Penning effect is included in the simulation. The comparison between the number of excitations which may lead to a Penning transfer, is shown for THGEM and GEM, explaining the less pronounced gain discrepancies observed in GEM.

X-Ray fluorescence imaging system based on Thick-GEM detectors

“…As a way to validate the simulations performed in this work, we compare the results obtained for the gain in Thick-GEMs in the simulations with some experimental results [46]. Discrepancies between experimental and simulated values for detector's gain were verified by some research groups [45] and one of the justifications found for such a difference is related to the value chosen for the Penning coefficient (r pen ) in the gaseous mixture .…”

“…It is possible to find in the literature a large number examples and results of simulations for GEM like detectors [44,45,46]. The first simulations performed in this work had the purpose of validating the code and the analysis methods using published data.…”

“…A Thick-GEM unit cell similar to the one created by [45] was modeled, with a drift region of 5 mm and an electric field of 500 V/cm, and an induction region of 2 mm with a field of 2000 V/cm. The hole diameter in the copper layer has 600 µm, while in the substrate it has 400 µm, creating a clearance ring.…”

Desenvolvimento de Detectores a Gás de Padrão Microscópico para Experimentos com Raios X

“…Em um caso geral, onde o campo elétrico não é uniforme, o parâmetro α não é constante, variando em função da distância até o fio (Majewski, 1996). É conhecido na literatura que o campo é uniforme em pontos distantes dos fios em um detector MWPC e possui simetria radial nas proximidades dos mesmos (Knoll, 1979 (Penning, 1928(Penning, , 1934 enquanto estudava descargas em gases e observou que o potencial de descarga em misturas de neon, argônio e mercúrio é menor do que em gases nobres puros, atribuindo esse efeito a estados metaestáveis (Druyvesteyn & Penning, 1940 rPen Mistura (Proporção) Referência 0,55 Ar/CO2 (70% / 30%) (Dildick, 2011) 0,70 Ar/CO2 (70% / 30%) (Nemallapudi, 2012) 0,45 Ar/CO2 (90% / 10%) (Nemallapudi, 2012) 0,51 Ar/CO2 (80% / 20%) (Sipaj, 2012) 0,57 Ar/CO2 (70% / 30%) (Azevedo et al, 2016) 0,51 Ar/CO2 (70% / 30%) (Malinowski et al, 2018) 0,32 Ar/Isobutano (95% / 5%) (Ogawa & Aoki, 2017) 43…”

“…A abordagem por meio de simulações em se tratando de detectores de partículas é normalmente aplicada ao estudo de características de difícil observação, como por exemplo, estudo de seções de choque, a absorção de fótons no gás (Biagi, 1995;Henke, Gullikson, & Davis, 1993), o efeito avalanche (Alkaa, Mitev, & Segur, 2007;Azevedo et al, 2016;Purba Bhattacharya, Mohanty, Mukhopadhyay, Majumdar, & Luz, 2017;Date et al, 2000;Matoba, Hirose, Sakae, & Kametani, 1985), entre outras. Além dessas propriedades, há outras que são recorrentes e servem tanto para a comparação com dados experimentais quanto no estudo e proposição de novos dispositivos.…”