Electron–ion recombination rate constants in gaseous, liquid, and solid argon

Abstract

Electron drift mobilities μe and electron–ion recombination rate constants kr in gaseous, liquid, and solid argon have been measured by the analysis of transient current induced with the irradiation of an x-ray pulse as functions of temperature and external electric field strength except solid. The effect of external dc electric field on kr up to ∼3×10−3 Td (1 Td=10−17 V cm2/molecule) was examined in gaseous and liquid phases. The observed kr values in both liquid and gas phases were found to be much smaller than those calculated by the reduced Debye equation. The deviation, which is bigger in gas than in liquid, has been compared with recent theoretical studies1–5 which were presented to explain our previous data on the kr values for methane.6 It has been concluded that the recombination also in liquid and gaseous argon is not a usual diffusion-controlled reaction. In the solid phase the observed kr values were almost in agreement with those calculated by the reduced Debye equation. The electron–ion recombination rate constants in both liquid and gas phases increased almost linearly with an external dc electric field up to a critical electric field strength below which electron mobility was nearly constant, and decreased with further increase in the electric field where electron mobility also decreased.

Electron–ion recombination in radiation tracks in liquid argon: a computer simulation study

“…The dielectric constant e = 1.49 [6] was used. In the simulations, electrons were started at the distance r 0 = 0.5 nm from their parent cations, with the kinetic energy E k,0 = 5 eV.…”

“…1). Since the mobility of the positive charge in LAr (l þ ¼ 1:52 Â 10 À3 cm 2 /Vs) [24] is much lower than the zero-field electron mobility (l 0 ¼ 490 cm 2 /Vs) [6], we assume that the cations are immobile in the simulation. However, this assumption can be relaxed in future versions of our method.…”

“…These changes lead to formation of cation clusters, which facilitate the electron ''capture'' by the cations by providing efficient, vibrational channels of dissipating the electron energy. By considering the effect of cation clusters on electron-ion reactions, Wojcik and Tachiya [23] were able to explain the rate constants of the bulk electron-ion recombination in dense gaseous and liquid argon, measured by Shinsaka et al [6], solving the problem that had long challenged the theoretical studies.…”

“…Electron transport and electron-ion recombination in irradiated liquid argon (LAr) have been studied by many research groups [1][2][3][4][5][6][7]. The specific features of LAr, such as the high electron mobility and high free-ion yield, motivated the theoretical studies [4,[8][9][10][11][12][13].…”

Liquid noble gas detectors for low energy particle physics

“…Critical reviews of these and other models can be found in [140,141,142,143,75]. Original papers such as [144,145,135,134] may also constitute useful reading.…”