کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
8165990 | 1526223 | 2018 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Improved Lithium Iodide neutron scintillator with Eu2+ activation II: Activator zoning and concentration effects in Bridgman-grown crystals
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موضوعات مرتبط
مهندسی و علوم پایه
فیزیک و نجوم
ابزار دقیق
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![عکس صفحه اول مقاله: Improved Lithium Iodide neutron scintillator with Eu2+ activation II: Activator zoning and concentration effects in Bridgman-grown crystals Improved Lithium Iodide neutron scintillator with Eu2+ activation II: Activator zoning and concentration effects in Bridgman-grown crystals](/preview/png/8165990.png)
چکیده انگلیسی
We have previously reported on the formation of Suzuki Phase precipitate particles as a result of the addition of the divalent activator ion Eu 2+ to the monovalent alkali halide host LiI. [Boatner et al. (2017)]. These precipitates form during Bridgman or other melt-growth processes, even at low Eu2+ concentrations (e.g., 0.1% EuI2 doping), and scatter the scintillation light reducing the optical transparency of the scintillator and adversely affecting its radiation-detection performance. In our prior work, we developed a two-stage thermal-treatment method for the post-growth removal of the Suzuki Phase particles and the realization of a significant improvement in the optical transparency and associated neutron-detection of LiI:Eu2+ scintillators. These improvements resulted in neutron-detection performance that is superior to GS-20 glass and that allows for the application of pulse height gamma-ray discrimination over a wide range of gamma ray energies as opposed to pulse shape discrimination. Here, we apply the two-stage thermal-processing method for the removal of Suzuki phase precipitates and carry out an in-depth study, first, of the neutron scintillator performance versus the Eu2+ activator-ion-concentration spatial variation as a result of zoning effects during the Bridgman growth of LiI:Eu2+ and, second, of the effects of varying the initial Eu2+ activator ion concentration prior to crystal growth. The Eu2+ zoning variation results allow one to identify and select the most efficient location of the scintillation performance in a directionally solidified single-crystal boule. The present study of the initial activator concentration levels shows that there are, in fact, two distinct types of luminescence centers with varying performance properties - one that occurs only at low EuI2 addition levels (e.g., 0.01 to 0.06 %EuI2) and that is quickly replaced by a second luminescing center with increasing Eu2+ content (e.g., at â¼0.1% EuI2). The light yield for the luminescing center formed using a Eu activator in LiI is a critical function of the Eu concentration in the range of 0.01 to 0.1 % EuI2, and a high light yield of 100,000 photons/neutron is observed at the 0.06 %EuI2additive level prior to thermal processing.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment - Volume 903, 21 September 2018, Pages 8-17
Journal: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment - Volume 903, 21 September 2018, Pages 8-17
نویسندگان
L.A. Boatner, E.P. Comer, G.W. Wright, J.O. Ramey, R.A. Riedel, G.E. Jr., J.A. Kolopus,