Pressure effects on the X-ray intrinsic position resolution in noble gases and mixtures

Abstract

A study of the gas pressure effect in the position resolution of an interacting X-or gamma-ray photon in a gas medium is performed. The intrinsic position resolution for pure noble gases (Argon and Xenon) and their mixtures with CO 2 and CH 4 were calculated for several gas pressures (1-10 bar) and for photon energies between 5.4 and 60.0 keV, being possible to establish a linear match between the intrinsic position resolution and the inverse of the gas pressure in that energy range.In order to evaluate the quality of the method here described, a comparison between the available experimental data and the calculated one in this work, is done and discussed. In the majority of the cases, a strong agreement is observed. Keywords: Gaseous detectors; Gaseous imaging and tracking detectors; Charge transport and multiplication in gas; Detector modelling and simulations I (interaction of radiation with matter, interaction of photons with matter, interaction of hadrons with matter, etc) ArXiv ePrint: 1605.06256

Time and band-resolved scintillation in time projection chambers based on gaseous xenon

“…A more general fitting procedure should involve the formation times, but there is no sensitivity to them in present conditions and thus it destabilizes the fit. Moreover, for xenon above 2 bar the shape of the 2nd continuum emission remains largely unchanged as shown in [33]. For all four PMs a %-level afterpulsing at a time delay around 250 ns with respect to the main signal peak was observed.…”

“…Although uncertainties in W sc for X-ray and electron excitation have been historically reported to be considerably larger, in the range 60-110 eV [27][28][29][30], recent studies point to values compatible with the ones measured for α particles [31]. Furthermore, state of the art calculations of the seed states stemming from X-ray and MeV-electron excitation [32], once coupled to a microscopic description of the atomic/excimer cascade, can reproduce the main features of the scintillation spectrum of weakly quenched xenon mixtures [33], providing W sc = 39 ± 1 eV in the pressure range 1-10 bar. Calculations provide time and band-resolved spectra in a range of pressures from 0.1 to 10 bar and wavelengths from 145 nm to 1300 nm, for %-levels of common molecular additives.…”

“…In general, the triplet time constant of the second continuum stayed in the range τ * =85-98 ns during the measurements (compared to a world average of τ = 100.9 ± 0.7 ns cited for instance in [47]). This means, if using the quenching rates of N 2 in xenon from [53] and the formulas in [33], that N 2 concentrations can be estimated to be in the range f N 2 300-500 ppms, following the standard Stern-Volmer relation:…”

Gaseous and dual-phase time projection chambers for imaging rare processes

“…In table 3 we show N and E d /N -scalings that are known to be highly accurate in the practice of gaseous electronics such as those of the attachment, charge and light multiplication coefficients, drift-diffusion parameters [148,248] and particle range [249]. We also give some approximate scalings for the transparency and scintillation probability according to formulas derived in previous sections.…”

Microscopic simulation of xenon-based optical TPCs in the presence of molecular additives

“…Recently, the ionization cloud stemming from the transport of energetic electrons and X-rays up to 60 keV has been studied with Degrad through position resolution data for argon and xenon in the range 1-10 bar, showing good agreement [34,35]. The program is benchmarked as well with electron cloud size data from Kobetich and Katz [36], in the range 100eV-1MeV.…”