Scintillation properties of CsI:In single crystals

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Optical and scintillation properties of CsI:In crystals

The work is dedicated to study of optical and scintillation properties of CsI:In crystals. Using the Bridgeman method a concentration row of CsI:In single crystals was grown with the dopant content from 10⁻⁴ to 10⁻¹ mol. %. The segregation coefficient of In in CsI was estimated to be ~0.15. In CsI:In luminescence spectra one symmetric band is observed, peaking around 545 nm, with FWHM of 0.46 eV. Under intracenter excitation 1.9 μ s exponential decay was observed. The light yield under gamma excitation of ¹³⁷Cs isotope (662 keV), measured with a shaping time of 10 μ s, was 27 000 photons/MeV. The radio-luminescence yield of CsI:In , measured by the current mode method, approached to that of CsI:Tl . Probably, this difference is connected with the presence of a stronger afterglow in CsI:In crystals

Comparison of prompt and delayed photofission neutron detection techniques using different types of radiation detectors

Conference of 2016 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room-Temperature Semiconductor Detector Workshop, NSS/MIC/RTSD 2016 ; Conference Code:131365International audienceFor several years, detection of various threats on country borders plays a significant role in the frame of Homeland Security applications. One of this threat is the illicit trafficking of nuclear materials (especially including Special Nuclear Material - SNM - 235U, 233U or 239Pu), which can be potentially used for production of nuclear weapon as well as radiological dispersal device (RDD) - known also as a "dirty bomb". In order to detect the potentially hidden nuclear material, systems using linear accelerators and a group of detectors are developed by several scientific groups around the world. Besides solutions focusing on detection of delayed γ-rays or neutrons, also the systems dedicated for prompt neutron detection were proposed. One of the possible prompt neutron detection technique is known as Threshold Activation Detection (TAD). This technique relies on activation of 19F nuclei in the scintillator medium by fast neutrons and registration of high-energy particles and γ-rays from the decay of reaction products (for example, 19F(n,α)16N or 19F(n,p)19O). Recent studies in the frame of the European Horizon 2020 C-BORD project showed that, despite the low 19F(n,α)16N or 19F(n,p)19O reaction cross-section, the method could be a good solution for detection of shielded nuclear material. A benchmark of the TAD technique based on fluorine detectors with reference method focused on delayed neutron detection with 3He detectors will be presented in this paper. These experimental results were obtained using 9 MeV Varian Linatron M9 linear accelerator (LINAC)

CsI:Tl scintillation pulse shapes measured with a SiPM photodetector in a liquid nitrogen cryostat

A custom designed cryostat was constructed to measure the response of a CsI:Tl scintillator at temperatures close to the boiling point of liquid nitrogen (LN2). The scintillation light was collected by an HUV-HD SiPM from FBK with 6×6 mm2 area and 25×25 μm2 cell pitch. The crystal size was 5×6×7 mm3. All surfaces except the one facing the SiPM were covered with Teflon tape to enhance light collection by the photodetector. The performance of the experimental setup was verified at room temperature using analog electronics for signal processing. The crystal was mounted on a copper frame placed inside the LN2 cryostat. Since our goal was to measure the scintillation decay profiles, and the SiPM response at low temperatures becomes substantially slower than that observed at room temperature, the SiPM was mounted on a separate copper frame connected with the outer housing to keep it close to room temperature. The separation between the crystal surface and the SiPM was about 1.5 mm at room temperature, and it became smaller once the setup was cooled down to LN2 temperature, but even so the crystal and the photodetector were still separated. This approach allowed us to analyze scintillation pulse shapes of CsI:Tl at LN2 temperatures. An energy spectrum of 662 keV γ-rays from a 137Cs source was also recorded. The light yield of the CsI:Tl sample at LN2 temperature stands at about 6 % ÷ 8 % of the value observed at room temperature