Nonproportionality of Scintillator Detectors: Theory and Experiment. II

Payne, Stephen A.; Moses, W.W.; Sheets, S. A.; Ahle, L.; Cherepy, Nerine J.; Sturm, Benjamin W.; Dazeley, S.; Bizarri, Grégory; Choong, Woon-Seng

doi:10.1109/tns.2011.2167687

Cited by 107 publications

(109 citation statements)

References 53 publications

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“…(1)(2)(3)(4)(5)(6)(7). dn e dt = G e + D e ∇ 2 n e + µ e ∇ · n e − → E − (K 1e + S 1e )n e − Bn e n h − B ht n e n ht − K 3 n e n e n h − K 3 n e n e n ht (1)…”

Section: The Model and Its Numerical Solution In Electron Tracksunclassified

“…This is a significant factor affecting the various 2 nd and 3 rd order rate terms in Eqs. (1)(2)(3)(4)(5)(6) that depend on overlap of the electron and hole populations.…”

Section: The Model and Its Numerical Solution In Electron Tracksmentioning

confidence: 99%

“…Without going through all the rate and transport coefficient symbol names again, we comment generally that the carrier/exciton densities, the rate constants, and the transport coefficients carry the same symbols as in Eqs. (1)(2)(3) to indicate corresponding physical quantities, except now the fact of being trapped on the activator is indicated by the subscript "t"on all such terms. To illstrate the meaning of a few of the trapped carrier/exciton terms, for example, +S 1e n e is the rate of trapping thermalized electrons on the activator dopant, −B et n et n h is the bimolecular rate of converting trapped electron population, n et , into trapped excitons feeding the corresponding source term in Eq.…”

Section: The Model and Its Numerical Solution In Electron Tracksmentioning

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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“…(1)(2)(3)(4)(5)(6)(7). dn e dt = G e + D e ∇ 2 n e + µ e ∇ · n e − → E − (K 1e + S 1e )n e − Bn e n h − B ht n e n ht − K 3 n e n e n h − K 3 n e n e n ht (1)…”

Section: The Model and Its Numerical Solution In Electron Tracksunclassified

“…This is a significant factor affecting the various 2 nd and 3 rd order rate terms in Eqs. (1)(2)(3)(4)(5)(6) that depend on overlap of the electron and hole populations.…”

Section: The Model and Its Numerical Solution In Electron Tracksmentioning

confidence: 99%

Section: The Model and Its Numerical Solution In Electron Tracksmentioning

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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“…For all known materials, the scintillation response is not proportional to the incident electron energy. [19][20][21][22] The total c-ray response thus varies from event to event broadening the full absorption peak. In Ref.…”

mentioning

confidence: 99%

Improvement of LaBr3:5%Ce scintillation properties by Li+, Na+, Mg2+, Ca2+, Sr2+, and Ba2+ co-doping

Alekhin

Biner

Krämer

et al. 2013

Journal of Applied Physics

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This paper reports on the effects of Li þ , Na þ , Mg 2þ , Ca 2þ , Sr 2þ , and Ba 2þ co-doping on the scintillation properties of LaBr 3 :5%Ce 3þ . Pulse-height spectra of various gamma and X-ray sources with energies from 8 keV to 1.33 MeV were measured from which the values of light yield and energy resolution were derived. Sr 2þ and Ca 2þ co-doped crystals showed excellent energy resolution as compared to standard LaBr 3 :Ce. The proportionality of the scintillation response to gamma and X-rays of Ca 2þ , Sr 2þ , and Ba 2þ co-doped samples also considerably improves. The effects of the co-dopants on emission spectra, decay time, and temperature stability of the light yield were studied. Multiple thermoluminescence glow peaks, decrease of the light yield at temperatures below 295 K, and additional long scintillation decay components were observed and related to charge carrier traps appearing in LaBr 3 :Ce 3þ with Ca 2þ , Sr 2þ , and Ba 2þ co-doping.

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“…2,6,21,29,35,36 It is attributed to radiationless electron-hole pair recombination in the regions of a high concentration n(x) of charge carriers along the ionization track as shown in Fig. 1.…”

Section: Discussionmentioning

confidence: 99%

Energy resolution and related charge carrier mobility in LaBr3:Ce scintillators

Khodyuk

Quarati

Alekhin

et al. 2013

Journal of Applied Physics

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The scintillation response of LaBr 3 :Ce scintillation crystals was studied as function of temperature and Ce concentration with synchrotron X-rays between 9 keV and 100 keV. The results were analyzed using the theory of carrier transport in wide band gap semiconductors to gain new insights into charge carrier generation, diffusion, and capture mechanisms. Their influence on the efficiency of energy transfer and conversion from X-ray or c-ray photon to optical photons and therefore on the energy resolution of lanthanum halide scintillators was studied. From this, we will propose that scattering of carriers by both the lattice phonons and by ionized impurities are key processes determining the temperature dependence of carrier mobility and ultimately the scintillation efficiency and energy resolution. When assuming about 100 ppm ionized impurity concentration in 0.2% Ce 3þ doped LaBr 3, mobilities are such that we can reproduce the observed temperature dependence of the energy resolution, and in particular, the minimum in resolution near room temperature is reproduced. V C 2013 AIP Publishing LLC. [http://dx

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Nonproportionality of Scintillator Detectors: Theory and Experiment. II

Cited by 107 publications

References 53 publications

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

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

Improvement of LaBr3:5%Ce scintillation properties by Li+, Na+, Mg2+, Ca2+, Sr2+, and Ba2+ co-doping

Energy resolution and related charge carrier mobility in LaBr3:Ce scintillators

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