Origin of the 4.1-eV luminescence in pure CsI scintillator

Nishimura, Hitoshi; Sakata, Masaru; Tsujimoto, Tokuzou; Nakayama, Masaaki

doi:10.1103/physrevb.51.2167

Cited by 82 publications

(117 citation statements)

References 24 publications

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“…As follows from Fig. 5, well-known selftrapped exciton (STE) triplet emission band at 340 nm (3.65 eV) [24] dominates over the entire investigated spectral range. Luminescence band at 295 nm seems to be complex due to the superposition of two other excitonic bands at 289 nm (4.3 eV) and 300 nm (4.1 eV).…”

Section: Resultsmentioning

confidence: 98%

F centre production in CsI and CsI–Tl crystals under Kr ion irradiation at 15 K

Попов

Balanzat

2000

Nuclear Instruments and Methods in Physics Research Section B:

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We present results of simultaneous in situ luminescence and optical absorption studies in scintillator CsI and CsI±Tl crystals, exposed to very dense electronic excitations induced by 86 Kr ions (8.63 MeV/amu). Irradiation at 15 K leads to the formation of the prominent F absorption band. In addition, several other features of the broad absorption between exciton and F bands were ascribed to an anion vacancy, a centre (240 nm), self-trapped hole, V k centre (410 nm) and interstitials, H centres (560 nm). We have found that low doping of thallium ($10 17 cm À3 ) causes the F centre formation to proceed more rapidly than in pure crystal. On the other hand, we were not able to create any amount of F centres in heavily doped CsI±Tl. We have shown that point defects created by heavy ions manifested themselves in luminescence ageing. Ó

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Section: Resultsmentioning

confidence: 98%

F centre production in CsI and CsI–Tl crystals under Kr ion irradiation at 15 K

Попов

Balanzat

2000

Nuclear Instruments and Methods in Physics Research Section B:

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“…This is the only rate term that produces light in the first 3 equations for a pure material. In the case of pure CsI, R 1E is the reciprocal of the radiative lifetime of the 3.7-eV Type II STE at 100 K, and of the 4.1-eV luminescence of the equilibrated Type I & II STEs at room temperature identified by Nishimura et al 36 The fourth term in Eq. (3) is a linear loss term from the exciton population involving two rate constants.…”

Section: The Model and Its Numerical Solution In Electron Tracksmentioning

confidence: 99%

“…In typical treatments of thermally quenched simple excited states, the radiative rate is independent of temperature and can be identified as the decay rate at low temperature. Nishimura et al 36 have shown that the STE luminescence in CsI comes from on-center (Type I) and off-center (Type II) lattice configurations that communicate over barriers and finally come into thermal equilibrium as temperature is raised above 250 K. The total radiative rate of the communicating STE configurations is thus temperature-dependent, which we write R 1E (T ). The temperature-dependent total light yield is then…”

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confidence: 99%

“…These two equations can be fitted to the data of Nishimura et al 36 as well as Amsler et al 55 and Mikhailik et al 56 to obtain the functions R 1E (T ) and K 1E (T ) from 100 K up to 295K. The following method has been used to obtain the values of R 1E (295K)andK 1E (295K) listed in Table I.…”

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confidence: 99%

“…50 and 61 the hopping rate of the STE is about the same as for the STH, so D E ≈ D h = 1.9 x 10 −13 cm 2 /s in Table II. The STE radiative emission rate constant R 1E at 100 K can be read from the temperature-dependence of STE decay time plotted by Nishimura et al 36 . Their temperature dependent luminescence spectra also confirm that the STE emission becomes nearly pure 3.7-eV band (Type II STE) from 100 K down to about 10 K, so R 1E at 100 K is the reciprocal of the 900-ns pure Type II STE lifetime.…”

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confidence: 99%

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Coupled rate and transport equations modeling proportionality of light yield in high-energy electron tracks: CsI at 295 K and 100 K; CsI:Tl at 295 K

Bizarri

et al. 2015

Phys. Rev. B

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A high-energy electron in condensed matter deposits energy by creation of electron-hole pairs whose density generally increases as the electron slows, reaching the order of 10 20 eh/cm 3 near the end of its track. The subsequent interactions of the electrons and holes include nonlinear rate terms and transport as first hot and then thermalized carriers in the nanometer-scale radial dimension of the track. Charge separation and strong radial electric fields occur in a material such as CsI with contrasting diffusion rates of self-trapped holes and hot electrons. Eventual radiative recombination has a nonlinear relation to the primary electron energy because of these interactions. This socalled intrinsic nonproportionality of electron response limits achievable energy resolution of a given scintillation radiation detector material. We use a system of coupled transport and rate equations to describe a pure host (3 equations) and one dopant (4 more equations per dopant). Applying it first to the experimentally well-characterized system of CsI and CsI:Tl in this work, we use results of picosecond absorption spectroscopy, interband z-scan measurements of nonlinear rate constants, and other experiments and calculations to determine most of the more than 20 rate and transport coefficients required for modeling. The model is solved in a track environment approximated as cylindrical and is compared to the proportionality curve and total light yield of undoped CsI at temperatures of 295 K and 100 K, as well as thallium dopant in CsI:Tl at 295 K. With this degree of validation, the space-and time-distributions of carriers and excitons, both untrapped and trapped, are examined within the model to gain an understanding of the main competitions controlling the nonproportionality of response.

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