Radiation-Stimulated Conductivity of Some Alkali Halides Induced by 50 ps Electron Pulse Irradiation

Aduev, B.P.; Aluker, E.D.; Belokurov, G.M.; Shvayko, V.N.

doi:10.1002/(sici)1521-3951(199807)208:1<137::aid-pssb137>3.3.co;2-i

Cited by 3 publications

(3 citation statements)

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“…Diffusion coefficients for free electrons and holes as a function of temperature estimated by eq are presented in Figure . It is worth noting that the diffusion coefficient for free electrons in CsI obtained here for 300 K is 30 times lower than the estimate made in ref . As can be seen, the diffusion coefficient for free electrons and holes has the same order of magnitude between 40 and 300 K. It falls by an order of magnitude as the temperature goes down to 20 K. For the sake of simplicity, for the simulation we took D e = 0.01 cm 2 s –1 and D h = 0.004 cm 2 s –1 for the whole temperature range.…”

Section: Verification Of the Modelmentioning

confidence: 46%

Kinetic Model of Energy Relaxation in CsI:A (A = Tl and In) Scintillators

et al. 2015

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A model of energy relaxation in alkali halide scintillators doped with Tl-like activators is presented. Interaction between thermalized charge carriers, their diffusion, and capture by traps are considered. The model of energy relaxation suggested in the work includes essential electron excited states in alkali halides doped with Tl-like activators. Self-trapping of holes occurs in alkali halides at LNT, giving rise to creation of self-trapped excitons (STEs). Thallium-like activator impurity can act both as an electron or a hole trap. Once both of the charge carriers are trapped by the dopant, activator recombination channel comes to action. The model is verified using CsI classical scintillation crystals doped with thallium and indium ions in a range of concentrations from 10–4 to 10–1 mol %. Temperature dependences of the STE and the activator-induced emission yield are measured as a function of the activator concentration under continuous X-ray excitation. A system of rate equations is used to simulate the applicability of the model under different excitation conditions. Evaluation of the parameters of the system is done for a numerical solution. The model of energy relaxation suggested allows to explain energy losses in CsI:A scintillators in a 10–300 K temperature range.

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Section: Verification Of the Modelmentioning

confidence: 46%

Kinetic Model of Energy Relaxation in CsI:A (A = Tl and In) Scintillators

et al. 2015

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“…The mobility of non-relaxed electrons, holes and excitons in CsI is rather high. The mobility of electrons was estimated as µe=8 cm 2 /V s at room temperature [21]. According to the Einstein formula,…”

Section: Iii4 the Role Of The Mobility Of Electronic Excitationsmentioning

confidence: 99%

Time-resolved luminescence Z-scan of CsI using power femtosecond laser pulses

Belsky

Fedorov

Gridin

et al. 2019

Radiation Measurements

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Time-resolved Z-scan technique gives the opportunity to obtain consistent data for dependence of the yield and decay kinetics from excitation density. The excitation by 4 th harmonics of femtosecond Ti:Sapphire laser (6.2 eV) allows to measure with wide dynamical range of excitation density (from 10 17 to 10 22 excitations per cubic centimeter) CsI luminescence. In the density range 10 18 -10 19 cm -3 the yield of 310 nm band (fast intrinsic luminescence) increases linearly with energy of the laser pulse, and yield of 430 nm band decreases inversely. In the same density range the subnanosecond decay of 310 nm band becomes slower and in microsecond kinetics of 430 nm band increases the contribution of nanosecond components.

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“…Thus for the relevant time range of these simulations the hole mobility in CsI can be taken as µ h = 0. The electron mobility in CsI at room temperature is µ e = 8 cm 2 /Vs, measured by a time‐of‐flight method after 20 ps electron pulse excitation 23. The static dielectric constant of CsI is ε = 5.65 24.…”

Section: Modeling the Competition Between Fast Carrier Diffusion Anmentioning

confidence: 99%

Excitation density, diffusion‐drift, and proportionality in scintillators

Williams

Grim

et al. 2010

Physica Status Solidi (b)

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Phone: þ1 336 758 5132, Fax: þ1 336 758 6142.Stopping of an energetic electron produces a track of high excitation density, especially near its end, and consequent high radial concentration gradient. The effect of high excitation density in promoting nonlinear quenching is generally understood to be a root cause of nonproportionality in scintillators. However, quantitative data on the kinetic rates of nonlinear quenching processes in scintillators are scarce. We report experimental measurements of second-order dipole-dipole rate constants governing the main nonlinear quenching channel in CsI, CsI:Tl, NaI, and NaI:Tl. We also show that the second of the extreme conditions in a track, i.e., radial concentration gradient, gives rise to fast ( picoseconds) diffusion phenomena which act both as a competitor in reducing excitation density during the relevant time of nonlinear quenching, and as a determiner of branching between independent and paired carriers, where the branching ratio changes with dE/dx along the primary electron track. To investigate the interplay of these phenomena in determining nonproportionality of light yield, we use experimentally measured rate constants and mobilities in CsI and NaI to carry out quantitative modeling of diffusion, drift, and nonlinear quenching evaluated spatially and temporally within an electron track which is assumed cylindrical Gaussian in this version of the model. 1 Introduction When an energetic electron is slowed and stopped in a scintillator (or any solid material with a band gap), the track of excitations left behind is characterized by at least two remarkably extreme numbers: (i) very high excitation density and (ii) very large concentration gradient of carriers and/or excitations. The first condition of high excitation density has been recognized for some time as crucial for setting rates of second-order (dipole-dipole) and third-order (Auger) quenching of local light yield in the vicinity of the track. However, with very few exceptions, those rate constants have not been determined. Therefore we present measurements of dipole-dipole quenching rate constants at high excitation density for three halide scintillators in the present work.In addition to the promotion of nonlinear quenching by high excitation density in a track, the high concentration gradient promotes radial diffusion of electrons and holes, which can limit the nonlinear quenching rates by rapidly diluting carrier concentration, and may affect linear rates by setting up charge separation. We show by numerical modeling of the diffusion and quenching processes together

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Radiation-Stimulated Conductivity of Some Alkali Halides Induced by 50 ps Electron Pulse Irradiation

Cited by 3 publications

References 0 publications

Kinetic Model of Energy Relaxation in CsI:A (A = Tl and In) Scintillators

Kinetic Model of Energy Relaxation in CsI:A (A = Tl and In) Scintillators

Time-resolved luminescence Z-scan of CsI using power femtosecond laser pulses

Excitation density, diffusion‐drift, and proportionality in scintillators

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