One of the most critical aspects for the application of a scintillation material in high energy physics is the degradation of properties of the material in an environment of highly ionizing particles ...in particular due to hadrons. There are presently several detector concepts in consideration being based on organic scintillator material for fast timing of charged particles or sampling calorimeters. We have tested different samples of the organic plastic scintillator EJ-260 produced by the company Eljen Technology (Sweetwater, TX, USA). The ongoing activity has characterized the relevant parameters such as light output, kinetics and temperature dependence. The study has focused on the change of performance after irradiation with 150 MeV protons up to an integral fluence of 5·1013 protons/cm2 as well as with a strong 60Co γ-source accumulating an integral dose of 100 Gy. The paper will report on the obtained results.
The development of novel scintillators for ionizing radiation detectors is still playing a significant role in high-energy physics, medical and homeland security applications. New detector concepts ...require a unique combination of the material properties like rising and decay times, light output and in the case of collider experiments the radiation hardness. cerium doped garnet type scintillation materials have been intensively developed in the last years. Among them, Y 3 Al 5 O 12 (YAG), Lu 3 Al 5 O 12 (LuAG) and Gd 3 Al 2 Ga 3 O 12 (GAGG) with high radiation hardness recognized for both gamma- and proton irradiation, were found to be the most promising materials. Many modern detector systems based on scintillation materials require high-count rates. This involves the use of bright scintillators with fast rise and decay times in combination with modern ultra-fast photodetectors such as SiPMs. A possible solution for such kind of applications is a family of lutetium-yttrium oxyorthosilicates (Lu 2(1-x) Y 2x SiO5, LSO, LYSO, YSO). Here we report on the characterization of different types of garnets with various dopants and in shapes of pixels and bulk and on the study of properties of LSO, LYSO, YSO solely doped by Ce as well LYSO materials with Ca and Mg co-doping from different producers.
Lead Tungstate (PbWO 4 , PWO) has become presently the most commonly used scintillator material for electromagnetic calorimetry in medium and high-energy physics. There exists substantial demand for ...future calorimeters such as the completion of the PANDA electromagnetic compatibility (EMC) as well as various detector projects under discussion at Jefferson Lab or Brookhaven National Laboratory in the United States. Nearly, 6700 crystals are missing for the barrel section of the PANDA-EMC since the successful mass production of PWO using the Czochralski method was stopped after bankruptcy of the Bogoroditsk Technical Chemical Plant (BTCP) in Russia. Intermediate research and development efforts with the Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai, China, as an existing producer exploiting the modified Bridgman method could not reach the required quality in a consistent manner. End of 2014, the CRYTUR (Turnov, Czech Republic) has restarted the development of lead tungstate based again on the Czochralski method with impressive progress. The modified and optimized technology has already produced full size samples of PWO-II quality. This paper will present a detailed status report on a first preproduction run of 89 crystals focusing on the achieved optical performance, light yield, kinetics, and temperature dependence and radiation hardness.
The future P¯ANDA experiment with a next generation detector will focus on hadron spectroscopy. It will use cooled anti-proton beams with a momentum between 1.5 GeV/c and 15 GeV/c interacting with ...various targets. This allows to directly form all states of all quantum numbers and measure their widths with an accuracy of a few tens of keV. The experiment will be located at the exceptional Facility for Anti-proton and Ion Research in Germany (FAIR), which is currently under construction. The electromagnetic target calorimeter of the P¯ANDA experiment has the challenging aim to detect high energy photons with excellent energy resolution over the full dynamic range from 15 GeV down to a few tens of MeV within a 2 T solenoid. The target calorimeter itself is divided into a barrel and two endcaps. The individual crystals will be read out with two precisely matched large area avalanche photo diodes. In the very inner part of the forward endcap vacuum phototetrodes will be used instead. To reach the demands of the experiment, improved PbWO4 (PWO) scintillator crystals, cooled down to −25°C have been chosen. They provide a fast decay time for highest count rates, short radiation length for compactness, improved light yield for lowest thresholds and excellent radiation hardness 1. The main part of the 15,740 crystals needed have been produced by the Bogoroditsk Plant of Technochemical Products (BTCP) in Russia. After stopping their business, a new potential producer for the missing 41% of crystals have been found. The company Crytur in Czech Republic provided 150 promising preproduction crystals so far. Except some of the very first produced crystals, all samples exceed the required high quality parameters. Most of them have already been used for the first major assembly stage of assembling one of the 16 barrel slice segments, which will be presented as well.
Recently, a new scintillation material DSB: Ce3+ was announced. It can be produced in a form of glass or nano-structured glass ceramics with application of standard glass production technology with ...successive thermal annealing. When doped with Ce3+, material can be applied as scintillator. Light yield of scintillation is near 100 phe/MeV. Un-doped material has a wide optical window from 4.5eV and can be applied to detect Cherenkov light. Temperature dependence of the light yield LY(T) is 0.05% which is 40 times less than in case of PWO. It can be used for detectors tolerant to a temperature variation between -20° to +20°C. Several samples with dimensions of 15x15x7 mm3 have been tested for damage effects on the optical transmission under irradiation with γ-quanta. It was found that the induced absorption in the scintillation range depends on the doping concentration and varies in range of 0.5-7 m−1. Spontaneous recovery of induced absorption has fast initial component. Up to 25% of the damaged transmission is recuperated in 6 hours. Afterwards it remains practically constant if the samples are kept in the dark. However, induced absorption is reduced by a factor of 2 by annealing at 50°C and completely removed in a short time when annealing at 100°C. A significant acceleration of the induced absorption recovery is observed by illumination with visible and IR light. This effect is observed for the first time in a Ce-doped scintillation material. It indicates, that radiation induced absorption in DSB: Ce scintillation material can be retained at the acceptable level by stimulation with light in a strong irradiation environment of collider experiments.
The scintillation properties and radiation hardness of undoped and Ce doped YAG crystals, which were grown from tungsten crucibles in the Ar + CO atmosphere and annealed under different conditions, ...have been evaluated. The scintillation crystals obtained under such conditions have a high scintillation yield, demonstrate short scintillation kinetics with the major component of ∼60 ns, and demonstrate high radiation resistance when irradiated with both γ-quanta and high energy protons. The obtained results open up the opportunity to produce high-temperature garnet crystals using iridium-free technology, which forms the basis for a technology for mass production at an affordable price.
The scintillator gadolinium aluminium gallium garnet (Gd3Al2Ga3O12, GAGG) was found to be an excellent material for application in non-homogeneous detecting cells for future calorimeters, operating ...in a harsh irradiation environment. GAGG, activated by cerium ions, can be used to detect γ-quanta and to absorb efficiently neutrons in a wide energy range. The capture of neutrons is accompanied by the emission of relatively soft γ-quanta which can be ignored at calorimetric measurements above 10 MeV. These findings create prospects to construct compact detectors for different purposes, from particle physics to industry.
This report presents results on the optical transmission damage of undoped and Ce doped Y3Al5O12 scintillation crystals under high fluence of 24GeV protons. We observed that, similarly to other ...middle heavy scintillators, it possesses the unique radiation hardness at fluence values as high as 5×1014p/cm2 and it is thus promising for the application in the detectors at High Luminosity LHC. The crystalline structure of the garnet scintillator allows to control and further optimize its scintillation parameters, such as scintillation decay time and emission wavelength, and shows a limited set of the radioisotopes after the irradiation with protons.
This report presents results on the significant improvement of GAGG:Ce based scintillation detector performance with temperature decrease. When temperature of a PMT based detector is lowered to ...−45 °C, its amplitude response at registration of γ-quanta is improved by 30%; FHHM was found to be better up to factor of 0.85, whereas scintillation kinetics become even faster in crystals co-doped with magnesium and magnesium and titanium. All this opens an opportunity for a wide application of GAGG scintillation detectors, particularly in a combination with SiPM photo-sensors, which signal-to-noise ratio would also improve with temperature decrease.
In the last forty years, application of crystalline materials in ionizing radiation detectors has played a crucial role in the discovery of matter properties and promoted a continuous progress in the ...detecting technique. Further concepts of the detectors at HEP experiments will require an unique combination of the material features, particularly in case of collider experiments. Crucially important becomes a minimal level of radiation damage effects under the electromagnetic part of ionizing radiation and energetic hadrons as well: low deterioration of the optical transmission, low level of afterglow and low level of radioluminescence due to radio-nuclides being generated due to secondary nuclear reactions in the detector material itself. A systematic study of the radiation hardness of inorganic optical and scintillation materials have been performed. We concluded that both oxide and fluoride crystals which consist of atoms with atomic number less than 60 will be reasonably survivable in the irradiation environment of future experiments at colliders. In this study we focused on the study of cheap, capable for a mass production glass (BaO*2SiO2) and DSB: Ce glass ceramics obtained from this glass. We also made this glass more heavy by admixing gadolinium oxide into the matrix. Glass with Gd3+ admixture possesses two times larger light yield than pure (BaO*2SiO2) glass and glass ceramics. Both types of the materials were produced as fibre and blocks of larger volume.
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