Detection characteristics of vertical Bridgman grown stilbene crystals for gamma rays using 60Co, 137Cs and 22Na gamma ray sources

Arulchakkaravarthi, A.; Santhanaraghavan, P.; Kumar, R.; Muralithar, S.; Ramasamy, P.; Nagarajan, T.; Lan, C.W.

doi:10.1016/s0254-0584(01)00561-2

Cited by 17 publications

(6 citation statements)

References 13 publications

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“…2), based on more than a decade of hydrologic and ecological investigations in the study area (Patterson 1989;Wolfe 1996a, b;Wolfe and League 1996;McCarthy and Evans 2000), whose essential features are preserved in the numerical model's structure and parameterization. Finally, the model's relative simplicity (two compartments, eight transfer terms) and parsimony (four parameters) may have helped mitigate against overspecification and false precision (Beven 1989;Perrin et al 2001;Lute and Luce 2017).…”

Section: Discussionmentioning

confidence: 99%

“…Such differences-especially varying degrees of model complexity-can have major implications for model transferability either in space (i.e., extrapolation to new wetlands in other geographic locations) or in time (i.e., model forecasting to predict future hydrologic conditions or hindcasting to simulate wetland hydrology over the decades prior to the beginning of hydrologic observations; Wenger and Olden 2012;Clark et al 2017;Lute and Luce 2017). Substantial evidence indicates that model transferability benefits from parsimony, meaning that simpler models (i.e., with fewer parameters and storage compartments) tend to perform as well or better than more complex models when validated using independent data sets (Beven 1989;Jakeman and Hornberger 1993;Leplastrier et al 2002;Perrin et al 2003;Chien and Mackay 2014;Lute and Luce 2017;Chien and Mackay 2020). Whereas more complex models may better approximate localized physical processes and generally enable closer fit in calibration, favorable calibration statistics for highly complex models may represent a form of overfitting (i.e., "overparameterization"; Beven 1989;Perrin et al 2001) causing such models to perform poorly when extrapolated to novel contexts (Wenger and Olden 2012;Lute and Luce 2017;Chien and Mackay 2020).…”

Section: Introductionmentioning

confidence: 99%

“…Substantial evidence indicates that model transferability benefits from parsimony, meaning that simpler models (i.e., with fewer parameters and storage compartments) tend to perform as well or better than more complex models when validated using independent data sets (Beven 1989;Jakeman and Hornberger 1993;Leplastrier et al 2002;Perrin et al 2003;Chien and Mackay 2014;Lute and Luce 2017;Chien and Mackay 2020). Whereas more complex models may better approximate localized physical processes and generally enable closer fit in calibration, favorable calibration statistics for highly complex models may represent a form of overfitting (i.e., "overparameterization"; Beven 1989;Perrin et al 2001) causing such models to perform poorly when extrapolated to novel contexts (Wenger and Olden 2012;Lute and Luce 2017;Chien and Mackay 2020). Hydroclimatic non-stationarity (e.g., from climate change) implies that the hydroclimatic conditions of the model calibration and validation time periods (generally the recent past) may be substantially different from those of the more distant past (hindcasting) or future (forecasting), creating potential for transferability problems (Vaze et al 2010;Coron et al 2012;Coron et al 2014;Magand et al 2015;Duethmann et al 2020).…”

Section: Introductionmentioning

confidence: 99%

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Increasing Hydroperiod in a Karst-depression Wetland Based on 165 Years of Simulated Daily Water Levels

Cartwright

Wolfe

2021

Wetlands

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The hydrology of seasonally inundated depression wetlands can be highly sensitive to climatic fluctuations. Hydroperiod—the number of days per year that a wetland is inundated—is often of primary ecological importance in these systems and can vary interannually depending on climate conditions. In this study we re-examined an existing hydrologic model to simulate daily water levels in Sinking Pond, a 35-hectare seasonally inundated karst-depression wetland in Tennessee, USA. We recalibrated the model using 22 years of climate and water-level observations and used the recalibrated model to reconstruct (hindcast) daily water levels over a 165-year period from 1855 to 2019. A trend analysis of the climatic data and reconstructed water levels over the hindcasting period indicated substantial increases in pond hydroperiod over time, apparently related to increasing regional precipitation. Wetland hydroperiod increased on average by 5.9 days per decade between 1920 and 2019, with a breakpoint around the year 1970. Hydroperiod changes of this magnitude may have profound consequences for wetland ecology, such as a transition from a forested wetland to a mostly open-water pond at the Sinking Pond site. More broadly, this study illustrates the needs for robust hydrologic models of depression wetlands and for consideration of model transferability in time (i.e., hindcasting and forecasting) under non-stationary hydroclimatic conditions. As climate change is expected to influence water cycles, hydrologic processes, and wetland ecohydrology in the coming decades, hydrologic model projections may become increasingly important to detect, anticipate, and potentially mitigate ecological impacts in depression wetland ecosystems.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Increasing Hydroperiod in a Karst-depression Wetland Based on 165 Years of Simulated Daily Water Levels

Cartwright

Wolfe

2021

Wetlands

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“…However, it is difficult to make a single-crystal stilbene scintillator larger than a few centimeters, and it is also prone to damage from thermal and mechanical shock [4,11]. The stilbene single crystals used in this study were grown using the Bridgeman-Stockbarger method [12], whose typical properties are presented in Table 1 [13]. The commercial stilbene single crystals, with dimensions of 25 mm (D) × 20 mm (H) and 50 mm (D) × 40 mm (H), were used in this study.…”

Section: Stilbene Single Crystalmentioning

confidence: 99%

Development of large-area composite stilbene scintillator for fast neutron detection

Lee

Son

et al. 2013

Journal of Nuclear Science and Technology

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Fast neutron applications have gained popularity with the growth of fast neutron production facilities. Covering a larger area and/or wider angle can be one of the advantages of a fast neutron detector. In the present study, a large-area composite stilbene scintillator with the dimensions of 200 mm (D) × 20 mm (H) was fabricated to examine its scintillation properties and to evaluate its applicability to fast neutron detection. The detector response of small-and large-area composite stilbene scintillators for neutrons and gamma rays was measured and compared with that of commercial and small single-crystal stilbene scintillators. To this end, the response of each scintillator was measured for radioisotopes as well as mono-energetic neutrons generated by a Tandem accelerator. The neutron-gamma separation performance of the largearea composite stilbene scintillator was evaluated in terms of figure-of-merit (FoM) using the digital pulse shape discrimination method. The composite stilbene scintillator showed good energy linearity, as determined from its recoil proton spectra, with reasonable n-γ separation capability. The results indicated that the composite stilbene scintillator could be applied to the field of fast neutron detection, especially when a large area and/or a wide angle is to be covered and could be a good alternative to liquid scintillators.

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“…A stilbene crystal scintillator was specially developed for neutron measurements during the 2011 KSTAR campaign. It was grown using the Bridgeman-Stockbager method [14]; typical properties are presented in table 1.…”

Section: Stilbene Crystal Scintillatormentioning

confidence: 99%

Performance improvement of neutron flux monitor at KSTAR

et al. 2012

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The evaluation of plasma performance in fusion reactors is carried out by various particle or ion detection systems. Neutron diagnostic systems are used to evaluate different aspects of plasma performance and are very important tools because they can directly detect the neutrons of D-D or D-T fusion reactions. Among them, the stilbene scintillator has good Pulse Shape Discrimination (PSD), a fast response of 10 ns and it can also evaluate neutron energy using an unfolding method. Because of these properties, it was proposed as a neutron flux monitor in the Korea Superconducting Tokamak Advanced Research magnetic fusion reactor (KSTAR). Under high radiation fields, specially designed electronics are necessary to measure only fast neutron spectra and to reject background gamma rays. In order to increase the data transfer rate for real-time evaluation of plasma performance, we have developed a Flash Analog to Digital Convertor (FADC) with a Field-Programmable Gate Array (FPGA) that implements a Digital Charge Comparison (DCC) algorithm. Performance evaluation of stilbene was conducted in a 2011 KSTAR campaign and it showed good results for measuring real-time neutron flux with temporal resolution of 1 ms, and it operated well under high magnetic field conditions.

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Detection characteristics of vertical Bridgman grown stilbene crystals for gamma rays using 60Co, 137Cs and 22Na gamma ray sources

Cited by 17 publications

References 13 publications

Increasing Hydroperiod in a Karst-depression Wetland Based on 165 Years of Simulated Daily Water Levels

Increasing Hydroperiod in a Karst-depression Wetland Based on 165 Years of Simulated Daily Water Levels

Development of large-area composite stilbene scintillator for fast neutron detection

Performance improvement of neutron flux monitor at KSTAR

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