Monte Carlo simulation of a position sensitive gamma ray detector

Abstract

The Monte Carlo method was employed to obtain the response of a position sensitive gamma ray detector. The basic unit consists of a scintillator bar coupled to two photon detectors. Determination of the position of interaction is obtained from the ratio of the light intensity measured at each extremity of the bar. Association of two or more detectors of this type can be used to build a system with potential use in positron emission tomography. For practical purposes, a CsI(Tl) bar with dimensions of 15 × 1 × 1 cm 3 was considered. Simulations were performed with the GEANT4 toolkit, using the physical processes of low-energy electromagnetic extension. Light attenuation coefficient and energy resolution of CsI(Tl) bars were included according to data found in the literature. Results obtained from detector irradiation with 511 keV annihilation photons indicate that the position of interaction can be determined with uncertainty of 3 mm. Simulations of positron sources placed between two detectors were also performed and two dimensional images were obtained.

A stochastic model of gamma-ray induced oxide charge distribution and threshold voltage shift of MOS transistors

“…Thus, the pro ce dure of charge Fig ure 1. Sche matic rep re sen ta tion of the cre ation of elec tron-hole pairs in duced by gamma ra di a tion, trap ping holes, and the re com bi na tion of electrons dis tri bu tion cal cu la tion is sim i lar to the Monte Carlo method [4,5], but dif fer ent from the de tailed Monte Carlo sim u la tion of ra di a tion ef fects in the gate ox ide which in clude fea tures of par ti cle trans port [9].…”

“…In this pa per, we are de vel op ing a new model for es ti mat ing gamma-ray in duced spa tial dis tri bu tion of charges in ox ide. This model, based on the Monte Carlo method [4,5], takes into ac count the sto chas tic na ture of gamma ray ab sorp tion, as well as the gen er ation and re com bi na tion of in duced charges. Also, the ef fect of the elec tric field es tab lished in the SiO 2 layer upon charge gen er a tion and re com bi na tion, as well as upon its spa tial dis tri bu tion, is taken into ac count.…”

A Model of Gamma-Ray Irradiation Effects in Silicon Dioxide Films and on Silicon Dioxide - Silicon Interface

“…Because the processes of gamma ray absorption and electron-hole pairs creation and recombination are stochastic processes, we assumed that they randomly occur with certain probability. Therefore, we assumed that the oxide is partitioned into a number of layers and dose is dispensed on number of portions D ∆ absorbed in oxide during time, t ∆ , similar as in [8]. We suppose that the number of produced electron-hole pairs in each layer during the time t ∆ is the Gaussian random variable.…”