Nonproportionality of Scintillator Detectors. IV. Resolution Contribution from Delta-Rays

Payne, Stephen A.

doi:10.1109/tns.2014.2387256

Cited by 15 publications

(5 citation statements)

References 38 publications

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“…The incident radiation initially produces fast electrons, either directly by fundamental light-matter interactions or indirectly via electron-electron scattering, that traverse the crystal and deposit their energy by exciting electron-hole pairs and plasmons. [23][24][25] This process occurs on the femtosecond timescale and gives rise to a distribution of low-energy carriers in a nanometer-sized region surrounding the electrons tracks. The excitation density increases with decreasing kinetic energy of the fast electron.…”

Section: Discussionmentioning

confidence: 99%

Ab initio prediction of fast non-equilibrium transport of nascent polarons in SrI2: a key to high-performance scintillation

et al. 2016

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The excellent light yield proportionality of europium-doped strontium iodide (SrI 2 :Eu) has resulted in state-of-the-art γ-ray detectors with remarkably high energy resolution, far exceeding that of most halide compounds. In this class of materials the formation of self-trapped hole polarons is very common. However, polaron formation is usually expected to limit carrier mobilities and has been associated with poor scintillator light-yield proportionality and resolution. Here, using a recently developed first-principles method, we perform an unprecedented study of polaron transport in SrI 2 , both for equilibrium polarons, as well as nascent polarons immediately following a self-trapping event. We propose a rationale for the unexpected high energy resolution of SrI 2 . We identify nine stable hole polaron configurations, which consist of dimerized iodine pairs with polaron binding energies of up to 0.5 eV. They are connected by a complex potential energy landscape that comprises 66 unique nearest-neighbor migration paths. Ab initio molecular dynamics simulations reveal that a large fraction of polarons is born into configurations that migrate practically barrier free at room temperature. Consequently, carriers created during γ-irradiation can quickly diffuse away reducing the chance for non-linear recombination, the primary culprit for non-proportionality and resolution reduction. We conclude that the flat, albeit complex, landscape for polaron migration in SrI 2 is key for understanding its outstanding performance. This insight provides important guidance not only for the future development of high-performance scintillators but also of other materials, for which large polaron mobilities are crucial such as batteries and solid state ionic conductors.

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Section: Discussionmentioning

confidence: 99%

Ab initio prediction of fast non-equilibrium transport of nascent polarons in SrI2: a key to high-performance scintillation

et al. 2016

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“…We used the most accurate physics settings (precisio) featuring a high-fidelity fully coupled photon, electron and positron radiation transport for our source-detector configuration. In addition, this module accounts for secondary electron production and transport, Landau fluctuations as well as X-ray fluorescence, all of which are essential for an accurate description of non-proportional scintillation effects 16 , 18 , 23 , 52 . Motivated by the range of the transported particles, lower kinetic energy transport thresholds were set to 1 keV for the scintillation crystals as well as the closest objects to the crystals, e.g.…”

Section: Methodsmentioning

confidence: 99%

Emulator-based Bayesian inference on non-proportional scintillation models by compton-edge probing

Breitenmoser,

Cerutti,

Butterweck

et al. 2023

Nat Commun

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Scintillator detector response modeling has become an essential tool in various research fields such as particle and nuclear physics, astronomy or geophysics. Yet, due to the system complexity and the requirement for accurate electron response measurements, model inference and calibration remains a challenge. Here, we propose Compton edge probing to perform non-proportional scintillation model (NPSM) inference for inorganic scintillators. We use laboratory-based gamma-ray radiation measurements with a NaI(Tl) scintillator to perform Bayesian inference on a NPSM. Further, we apply machine learning to emulate the detector response obtained by Monte Carlo simulations. We show that the proposed methodology successfully constrains the NPSM and hereby quantifies the intrinsic resolution. Moreover, using the trained emulators, we can predict the spectral Compton edge dynamics as a function of the parameterized scintillation mechanisms. The presented framework offers a simple way to infer NPSMs for any inorganic scintillator without the need for additional electron response measurements.

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“…The data was fitted using an empirical function developed based on the Payne's model [15][16][17][18][19], as shown by the orange curve in Fig. 5.…”

Section: Photon Response Measurementsmentioning

confidence: 99%

“…To understand the physics behind the phenomenon and the discrepancies observed, numerous remarkable studies have been published over the decades. These studies include the improvement of measurement techniques [10][11][12][13] as well as theoretical interpretations [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31], with a subset focusing on simulations.…”

Section: Introductionmentioning

confidence: 99%

Nonproportionality of NaI(Tl) scintillation detector for dark matter search experiments

Lee,

Adhikari,

Carlin

et al. 2024

Eur. Phys. J. C

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We present a comprehensive study of the nonproportionality of NaI(Tl) scintillation detectors within the context of dark matter search experiments. Our investigation, which integrates COSINE-100 data with supplementary $$\gamma $$ γ spectroscopy, measures light yields across diverse energy levels from full-energy $$\gamma $$ γ peaks produced by the decays of various isotopes. These $$\gamma $$ γ peaks of interest were produced by decays supported by both long and short-lived isotopes. Analyzing peaks from decays supported only by short-lived isotopes presented a unique challenge due to their limited statistics and overlapping energies, which was overcome by long-term data collection and a time-dependent analysis. A key achievement is the direct measurement of the 0.87 keV light yield, resulting from the cascade following electron capture decay of $$\mathrm {^{22}Na}$$ 22 Na from internal contamination. This measurement, previously accessible only indirectly, deepens our understanding of NaI(Tl) scintillator behavior in the region of interest for dark matter searches. This study holds substantial implications for background modeling and the interpretation of dark matter signals in NaI(Tl) experiments.

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Nonproportionality of Scintillator Detectors. IV. Resolution Contribution from Delta-Rays

Cited by 15 publications

References 38 publications

Ab initio prediction of fast non-equilibrium transport of nascent polarons in SrI2: a key to high-performance scintillation

Ab initio prediction of fast non-equilibrium transport of nascent polarons in SrI2: a key to high-performance scintillation

Emulator-based Bayesian inference on non-proportional scintillation models by compton-edge probing

Nonproportionality of NaI(Tl) scintillation detector for dark matter search experiments

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