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Sample records for pwo scintillation crystals

  1. Characterization and Recovery of Lead Tungstate (PWO4) Crystals

    NASA Astrophysics Data System (ADS)

    McShane, Abigail; Griggs, Dannie

    2016-09-01

    The potential of Lead Tungstate (PWO) crystals in EM calorimeters like the Neutral Particle Spectrometer at 12 GeV JLab and future particle identification detectors of the Electron Ion Collider has been researched extensively. The small Moliere radius of PWO crystals make them ideal for use in a compact detector and their light yield outperforms that of other heavy crystals. Recent measurements have shown large variations in crystal properties. This is a major concern for the construction of particle identification detectors. Testing of the crystal uniformity and understanding the origin of the variation have thus become necessary. The characterization of PWO includes measurements of the crystal dimensions, optical transmittance, both longitudinal and transverse, the light yield and decay kinetics to identify slow luminescence components, as well as tests of radiation hardness. Optical clarity after radiation damage can in principle be restored by stimulated recovery with light. Optical bleaching with blue light is the default method, but curing at longer wavelength may be possible. The results of crystal characterization and effects of radiation on optical properties, as well as the effectiveness and practicality of the LED curing system will be discussed. This work was supported in part by NSF Grant PHY-1306227.

  2. Application of two-photon absorption in PWO scintillator for fast timing of interaction with ionizing radiation

    NASA Astrophysics Data System (ADS)

    Auffray, E.; Buganov, O.; Korjik, M.; Fedorov, A.; Nargelas, S.; Tamulaitis, G.; Tikhomirov, S.; Vaitkevičius, A.

    2015-12-01

    This work was aimed at searching for fast phenomena in scintillators in sub-10-ps range, a benchmark timing for the time response of radiation detectors in particle colliders. The pump-and-probe optical absorption technique with a tunable-wavelength parametric oscillator as the pump and a continuous-spectrum source as the probe beam was used to study lead tungstate PbWO4 (PWO) single crystals. It is shown that the rise time of the probe pulse absorption induced by the pump pulse is shorter than the pump pulse width of 200 fs. The approximately linear dependence of the probe absorption on the pump pulse energy density evidences that the induced absorption is caused by two-photon absorption involving one probe and one pump photon. We demonstrate that the intensity of the induced absorption at certain wavelengths is influenced by gamma irradiation, provided that an appropriate light polarization is selected. The application of the irradiation-sensitive nonlinearity for fast timing in radiation detectors is discussed.

  3. Scintillation of lead tungstate crystal studied with single-electron beam from KUFEL

    SciTech Connect

    Rizwan, Mohamad Uozumi, Yusuke; Matsuo, Kazuki; Ohgaki, Hideaki; Kii, Toshiteru; Zen, Heishun; Tsamalaidze, Zviadi; Evtoukhovitch, Petr; Valentin, Samoilov

    2015-04-29

    Lead tungstate (PWO) crystal has a very fast response, high atomic density and high radiation hardness. Therefore, they are suitable to be used for high-energy nuclear data measurements under high-background circumstances. Although a good electron-ion separation with a pulse shape analysis technique is essential, scintillation pulse shapes have not been observed with electron beams of a wide energy range. A single-electron beam technique has been developed at Kyoto University Free Electron Laser (KUFEL), and electron beams of 4-38 MeV are available. During the experiments, single electron beams bombarded a PWO crystal. By using oscilloscope we observed scintillation pulses of a PWO crystal coupled with a photomultiplier tube. Measured spectra were compared with the simulation code of EGS5 to analyze scattering effects. As the result, the pulse amplitudes show good linearity and the pulse shapes are almost constant in the observed energy range.

  4. Mixed crystal organic scintillators

    DOEpatents

    Zaitseva, Natalia P; Carman, M Leslie; Glenn, Andrew M; Hamel, Sebastien; Hatarik, Robert; Payne, Stephen A; Stoeffl, Wolfgang

    2014-09-16

    A mixed organic crystal according to one embodiment includes a single mixed crystal having two compounds with different bandgap energies, the organic crystal having a physical property of exhibiting a signal response signature for neutrons from a radioactive source, wherein the signal response signature does not include a significantly-delayed luminescence characteristic of neutrons interacting with the organic crystal relative to a luminescence characteristic of gamma rays interacting with the organic crystal. According to one embodiment, an organic crystal includes bibenzyl and stilbene or a stilbene derivative, the organic crystal having a physical property of exhibiting a signal response signature for neutrons from a radioactive source.

  5. Investigating the Anisotropic Scintillation Response in Organic Crystal Scintillator Detectors

    NASA Astrophysics Data System (ADS)

    Schuster, Patricia Frances

    This dissertation presents several studies that experimentally characterize the scintillation anisotropy in organic crystal scintillators. These include measurements of neutron, gamma-ray and cosmic muon interactions in anthracene, a historical benchmark among organic scintillator materials, to confirm and extend measurements previously available in the literature. The gamma-ray and muon measurements provide new experimental confirmation that no scintillation anisotropy is present in their interactions. Observations from these measurements have updated the hypothesis for the physical mechanism that is responsible for the scintillation anisotropy concluding that a relatively high dE/dx is required in order to produce a scintillation anisotropy. The directional dependence of the scintillation output in liquid and plastic materials was measured to experimentally confirm that no scintillation anisotropy correlated to detector orientation exists in amorphous materials. These observations confirm that the scintillation anisotropy is not due to an external effect on the measurement system, and that a fixed, repeating structure is required for a scintillation anisotropy. The directional dependence of the scintillation output in response to neutron interactions was measured in four stilbene crystals of various sizes and growth-methods. The scintillation anisotropy in these materials was approximately uniform, indicating that the crystal size, geometry, and growth method do not significantly impact the effect. Measurements of three additional pure crystals and two mixed crystals were made. These measurements showed that 1) the magnitude of the effect varies with energy and material, 2) the relationship between the light output and pulse shape anisotropy varies across materials, and 3) the effect in mixed materials is very complex. These measurements have informed the hypothesis of the mechanism that produces the directional dependence. By comparing the various relationships

  6. Photonic crystal scintillators and methods of manufacture

    DOEpatents

    Torres, Ricardo D.; Sexton, Lindsay T.; Fuentes, Roderick E.; Cortes-Concepcion, Jose

    2015-08-11

    Photonic crystal scintillators and their methods of manufacture are provided. Exemplary methods of manufacture include using a highly-ordered porous anodic alumina membrane as a pattern transfer mask for either the etching of underlying material or for the deposition of additional material onto the surface of a scintillator. Exemplary detectors utilizing such photonic crystal scintillators are also provided.

  7. Measurement and optimization of the light collection uniformity in strongly tapered PWO crystals of the PANDA detector

    NASA Astrophysics Data System (ADS)

    Diehl, Stefan; Bremer, Daniel; Brinkmann, Kai-Thomas; Dormenev, Valery; Eissner, Tobias; Novotny, Rainer W.; Rosenbaum, Christoph; Zaunick, Hans-Georg

    2017-06-01

    The uniformity of the light collection is a crucial parameter for detectors based on inorganic scintillation crystals to guarantee a response proportional to the deposited energy. Especially in case of tapered crystals, like they are widely used to realize a 4π geometry of electromagnetic calorimeters (EMC) in high energy physics experiments, a strong non-uniformity is introduced by an additional focusing of the scintillation light due to the tapered geometry. The paper will discuss the determination and the reduction of the non-uniformity in strongly tapered lead tungstate crystals as used for the construction of the electromagnetic calorimeter of the PANDA detector at the future Facility for Antiproton and Ion Research (FAIR). Among different concepts for an uniformization a single de-polished lateral side face provided the optimum result with a remaining non-uniformity below 5% in good agreement with similar studies for the CMS ECAL at LHC. The impact on the achievable energy resolution in the energy regime of photons below 800 MeV is discussed in detail in comparison to GEANT4 simulations. The comparison of the response of two arrays with polished and de-polished crystals, respectively, shows in the latter case a significant improvement of the constant term of the parametrization of the energy resolution down to 0.5% accompanied by only very slight increase of the statistical term.

  8. Photon statistics in scintillation crystals

    NASA Astrophysics Data System (ADS)

    Bora, Vaibhav Joga Singh

    Scintillation based gamma-ray detectors are widely used in medical imaging, high-energy physics, astronomy and national security. Scintillation gamma-ray detectors are eld-tested, relatively inexpensive, and have good detection eciency. Semi-conductor detectors are gaining popularity because of their superior capability to resolve gamma-ray energies. However, they are relatively hard to manufacture and therefore, at this time, not available in as large formats and much more expensive than scintillation gamma-ray detectors. Scintillation gamma-ray detectors consist of: a scintillator, a material that emits optical (scintillation) photons when it interacts with ionization radiation, and an optical detector that detects the emitted scintillation photons and converts them into an electrical signal. Compared to semiconductor gamma-ray detectors, scintillation gamma-ray detectors have relatively poor capability to resolve gamma-ray energies. This is in large part attributed to the "statistical limit" on the number of scintillation photons. The origin of this statistical limit is the assumption that scintillation photons are either Poisson distributed or super-Poisson distributed. This statistical limit is often dened by the Fano factor. The Fano factor of an integer-valued random process is dened as the ratio of its variance to its mean. Therefore, a Poisson process has a Fano factor of one. The classical theory of light limits the Fano factor of the number of photons to a value greater than or equal to one (Poisson case). However, the quantum theory of light allows for Fano factors to be less than one. We used two methods to look at the correlations between two detectors looking at same scintillation pulse to estimate the Fano factor of the scintillation photons. The relationship between the Fano factor and the correlation between the integral of the two signals detected was analytically derived, and the Fano factor was estimated using the measurements for SrI2:Eu, YAP

  9. Review on photonic crystal coatings for scintillators

    NASA Astrophysics Data System (ADS)

    Knapitsch, Arno; Lecoq, Paul

    2014-11-01

    The amount of light and its time distribution are key factors determining the performance of scintillators when used as radiation detectors. However most inorganic scintillators are made of heavy materials and suffer from a high index of refraction which limits light extraction efficiency. This increases the path length of the photons in the material with the consequence of higher absorption and tails in the time distribution of the extracted light. Photonic crystals are a relatively new way of conquering this light extraction problem. Basically they are a way to produce a smooth and controllable index matching between the scintillator and the output medium through the nanostructuration of a thin layer of optically transparent high index material deposited at the coupling face of the scintillator. Our review paper discusses the theory behind this approach as well as the simulation details. Furthermore the different lithography steps of the production of an actual photonic crystal sample will be explained. Measurement results of LSO scintillator pixels covered with a nanolithography machined photonic crystal surface are presented together with practical tips for the further development and improvement of this technique.

  10. Neutron detection with single crystal organic scintillators

    SciTech Connect

    Zaitseva, N; Newby, J; Hamel, S; Carman, L; Faust, M; Lordi, V; Cherepy, N; Stoeffl, W; Payne, S

    2009-07-15

    Detection of high-energy neutrons in the presence of gamma radiation background utilizes pulse-shape discrimination (PSD) phenomena in organics studied previously only with limited number of materials, mostly liquid scintillators and single crystal stilbene. The current paper presents the results obtained with broader varieties of luminescent organic single crystals. The studies involve experimental tools of crystal growth and material characterization in combination with the advanced computer modeling, with the final goal of better understanding the relevance between the nature of the organic materials and their PSD properties. Special consideration is given to the factors that may diminish or even completely obscure the PSD properties in scintillating crystals. Among such factors are molecular and crystallographic structures that determine exchange coupling and exciton mobility in organic materials and the impurity effect discussed on the examples of trans-stilbene, bibenzyl, 9,10-diphenylanthracene and diphenylacetylene.

  11. Characterization of PbWO4 crystals for high-energy physics experiments

    NASA Astrophysics Data System (ADS)

    Kim, M. J.; Park, H.; Kim, H. J.

    2016-09-01

    High-energy physics (HEP) experiments have employed many new types of scintillators. Specifically, bismuth germanate, thallium-doped cesium iodide, and lead tungstate (PbWO4, PWO) have been used for the L3 experiment; CLEO II, Belle and BES-III; and CMS, respectively. PWO has particularly beneficial properties, such as high density, fast decay time, short radiation length and radiation hardness. In this study, we tested the PWO crystals at low temperatures to determine their applicability in future calorimeters. Various crystals from the Proton Antiproton Annihilations at Darmstadt (PANDA) experiment in Giessen, the Bogoroditsk Techno-Chemical Plant (BTCP) in Russia and by Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS) in China were investigated. We studied the scintillation properties of PWO crystals, such as their X-ray luminescence, relative light yields, absolute light yields, energy resolutions, decay times and longitudinal uniformities of their light yields. In addition, we measured the temperature dependences of the light yields and decay times by using a 137Cs γ-ray source. The emission spectra of the PWO crystals consisted of a broad band from 350 nm to 700 nm, and the peak emission wavelength in each spectrum was 420 nm. The emission spectra of the PWO crystals from SICCAS were slightly shifted to longer wavelengths compared with those of the crystals from the other institutions.

  12. Barium iodide single-crystal scintillator detectors

    NASA Astrophysics Data System (ADS)

    Cherepy, Nerine J.; Hull, Giulia; Niedermayr, Thomas R.; Drobshoff, Alexander; Payne, Stephen A.; Roy, Utpal N.; Cui, Yunlong; Bhattacharaya, Ajanta; Harrison, Melissa; Guo, Mingsheng; Groza, Michael; Burger, Arnold

    2007-09-01

    We find that the high-Z crystal Barium Iodide is readily growable by the Bridgman growth technique and is less prone to crack compared to Lanthanum Halides. We have grown Barium Iodide crystals: undoped, doped with Ce 3+, and doped with Eu 2+. Radioluminescence spectra and time-resolved decay were measured. BaI II(Eu) exhibits luminescence from both Eu 2+ at 420 nm (~450 ns decay), and a broad band at 550 nm (~3 μs decay) that we assign to a trapped exciton. The 550 nm luminescence decreases relative to the Eu 2+ luminescence when the Barium Iodide is zone refined prior to crystal growth. We also describe the performance of BaI II(Eu) crystals in experimental scintillator detectors.

  13. New Scintillating Crystals for PET Scanners

    NASA Astrophysics Data System (ADS)

    Lecoq, Paul

    2002-01-01

    Systematic R&D on basic mechanism in inorganic scintillators, initiated by the Crystal Clear Collaboration at CERN 10 years ago, has contributed not to a small amount, to the development of new materials for a new generation of medical imaging devices with increased resolution and sensitivity. The first important requirement for a scintillator to be used in medical imaging devices is the stopping power for the given energy range of X and γ rays to be considered, and more precisely the conversion efficiency. A high light yield is also mandatory to improve the energy resolution, which is essentially limited by the photostatistics and the electronic noise at these energies. A short scintillation decay time allows to reduce the dead time and therefore to increase the limiting counting rate. When all these requirements are fulfilled the sensitivity and image contrast are increased for a given patient dose, or the dose can be reduced. Examples of new materials under development by the Crystal Clear Collaboration will be given with an emphasis on the major breakthrough they can bring in medical imaging, as compared to present equipments.

  14. Crystal growth and scintillation properties of strontium iodide scintillators

    SciTech Connect

    van Loef, Edgar; Wilson, Cody; Cherepy, Nerine; Payne, Steven; Choong, Woon-Seng; Moses, William W.; Shah, Kanai

    2009-06-01

    Single crystals of SrI{sub 2}:Eu and SrI{sub 2}:Ce/Na were grown from anhydrous iodides by the vertical Bridgman technique in evacuated silica ampoules. Growth rates were of the order of 5-30 mm/day. Radioluminescence spectra of SrI{sub 2}:Eu and SrI{sub 2}:Ce/Na exhibit a broad band due to Eu{sup 2+} and Ce{sup 3+} emission, respectively. The maximum in the luminescence spectrum of SrI{sub 2}:Eu is found at 435 nm. The spectrum of SrI{sub 2}:Ce/Na exhibits a doublet peaking at 404 and 435 nm attributed to Ce{sup 3+} emission, while additional impurity - or defected - related emission is present at approximately 525 nm. The strontium iodide scintillators show very high light yields of up to 120,000 photons/MeV, have energy resolutions down to 3% at 662 keV (Full Width Half Maximum) and exhibit excellent light yield proportionality with a standard deviation of less than 5% between 6 and 460 keV.

  15. Scintillation of Un-doped ZnO Single Crystals

    SciTech Connect

    Colosimo, A. M.; Ji, Jianfeng; Stepanov, P. S.; Boatner, L. A.; Selim, F. A.

    2016-01-07

    In this paper, scintillation properties are often studied by photo-luminescence (PL) and scintillation measurements. In this work, we combine X-ray-induced luminescence (XRIL) spectroscopy [Review of Scientific Instruments 83, 103112 (2012)] with PL and standard scintillation measurements to give insight into the scintillation properties of un-doped ZnO single crystals. XRIL revealed that ZnO luminescence proportionally increases with X-ray power and exhibits excellent linearity - indicating the possibility of developing radiation detectors with good energy resolution. Finally, by coupling ZnO crystals to fast photomultiplier tubes and monitoring the anode signal, rise times as fast as 0.9 ns were measured.

  16. Scintillation properties of TGG and TSAG crystals for imaging applications

    NASA Astrophysics Data System (ADS)

    Yanagida, Takayuki; Okada, Go; Kojima, Takahiro; Hayashi, Takeshi; Ushizawa, Jisaburou; Kawano, Naoki; Kawaguchi, Noriaki

    2017-08-01

    Optical and scintillation properties of TGG (Tb3Ga5O12) and TSAG (Tb3Sc2Al3O12) crystals were investigated, and capabilities to be used as a scintillator screen were demonstrated. In photoluminescence (PL) spectra, some emission lines due to Tb3+4f-4f transitions appeared from 500 to 700 nm. PL quantum yields of TGG and TSAG were 6.5% and 50.9%, respectively. When irradiated by X-rays, these crystals showed intense scintillation, and the emission wavelengths were the same as those in PL spectra. The scintillation decay times of TGG and TSAG were 94 and 678 μs, respectively. Further, we have demonstrated X-ray imaging using both TSGG and TSAG crystal plates and confirmed a capability as scintillator screens.

  17. Divalent europium doped and un-doped calcium iodide scintillators: Scintillator characterization and single crystal growth

    DOE PAGES

    Boatner, L. A.; Ramey, J. O.; Kolopus, J. A.; ...

    2015-02-21

    Initially, the alkaline-earth scintillator, CaI2:Eu2+, was discovered around 1964 by Hofstadter, Odell, and Schmidt. Serious practical problems quickly arose, however, that were associated with the growth of large monolithic single crystals of this material due to its lamellar, mica-like structure. As a result of its theoretically higher light yield, CaI2:Eu2+ has the potential to exceed the excellent scintillation performance of SrI2:Eu2+. In fact, theoretical predictions for the light yield of CaI2:Eu2+ scintillators suggested that an energy resolution approaching 2% at 662 keV could be achievable. Like the early SrI2:Eu2+ scintillator, the performance of CaI2:Eu2+ scintillators has traditionally suffered due, atmore » least in part, to outdated materials synthesis, component stoichiometry/purity, and single-crystal-growth techniques. Based on our recent work on SrI2:Eu2+ scintillators in single-crystal form, we have developed new techniques that are applied here to CaI2:Eu2+ and pure CaI2 with the goal of growing large un-cracked crystals and, potentially, realizing the theoretically predicted performance of the CaI2:Eu2+ form of this material. Calcium iodide does not adhere to modern glassy carbon Bridgman crucibles - so there should be no differential thermal-contraction-induced crystal/crucible stresses on cooling that would result in crystal cracking of the lamellar structure of CaI2. Here we apply glassy carbon crucible Bridgman growth, high-purity growth-charge compounds, our molten salt processing/filtration technique, and extended vacuum-melt-pumping methods to the growth of both CaI2:Eu2+ and un-doped CaI2. Moreover, large scintillating single crystals were obtained, and detailed characterization studies of the scintillation properties of CaI2:Eu2+ and pure CaI2 single crystals are presented that include studies of the effects of plastic deformation of the crystals on the scintillator performance.« less

  18. Divalent europium doped and un-doped calcium iodide scintillators: Scintillator characterization and single crystal growth

    SciTech Connect

    Boatner, L. A.; Ramey, J. O.; Kolopus, J. A.; Neal, John S.

    2015-02-21

    Initially, the alkaline-earth scintillator, CaI2:Eu2+, was discovered around 1964 by Hofstadter, Odell, and Schmidt. Serious practical problems quickly arose, however, that were associated with the growth of large monolithic single crystals of this material due to its lamellar, mica-like structure. As a result of its theoretically higher light yield, CaI2:Eu2+ has the potential to exceed the excellent scintillation performance of SrI2:Eu2+. In fact, theoretical predictions for the light yield of CaI2:Eu2+ scintillators suggested that an energy resolution approaching 2% at 662 keV could be achievable. Like the early SrI2:Eu2+ scintillator, the performance of CaI2:Eu2+ scintillators has traditionally suffered due, at least in part, to outdated materials synthesis, component stoichiometry/purity, and single-crystal-growth techniques. Based on our recent work on SrI2:Eu2+ scintillators in single-crystal form, we have developed new techniques that are applied here to CaI2:Eu2+ and pure CaI2 with the goal of growing large un-cracked crystals and, potentially, realizing the theoretically predicted performance of the CaI2:Eu2+ form of this material. Calcium iodide does not adhere to modern glassy carbon Bridgman crucibles - so there should be no differential thermal-contraction-induced crystal/crucible stresses on cooling that would result in crystal cracking of the lamellar structure of CaI2. Here we apply glassy carbon crucible Bridgman growth, high-purity growth-charge compounds, our molten salt processing/filtration technique, and extended vacuum-melt-pumping methods to the growth of both CaI2:Eu2+ and un-doped CaI2. Moreover, large scintillating single crystals were obtained, and detailed characterization studies of the

  19. Visible scintillation photodetector device incorporating chalcopyrite semiconductor crystals

    DOEpatents

    Stowe, Ashley C.; Burger, Arnold

    2017-04-04

    A photodetector device, including: a scintillator material operable for receiving incident radiation and emitting photons in response; a photodetector material coupled to the scintillator material operable for receiving the photons emitted by the scintillator material and generating a current in response, wherein the photodetector material includes a chalcopyrite semiconductor crystal; and a circuit coupled to the photodetector material operable for characterizing the incident radiation based on the current generated by the photodetector material. Optionally, the scintillator material includes a gamma scintillator material and the incident radiation received includes gamma rays. Optionally, the photodetector material is further operable for receiving thermal neutrons and generating a current in response. The circuit is further operable for characterizing the thermal neutrons based on the current generated by the photodetector material.

  20. Event localization in bulk scintillator crystals using coded apertures

    NASA Astrophysics Data System (ADS)

    Ziock, K. P.; Braverman, J. B.; Fabris, L.; Harrison, M. J.; Hornback, D.; Newby, J.

    2015-06-01

    The localization of radiation interactions in bulk scintillators is generally limited by the size of the light distribution at the readout surface of the crystal/light-pipe system. By finding the centroid of the light spot, which is typically of order centimeters across, practical single-event localization is limited to 2 mm/cm of crystal thickness. Similar resolution can also be achieved for the depth of interaction by measuring the size of the light spot. Through the use of near-field coded-aperture techniques applied to the scintillation light, light transport simulations show that for 3-cm-thick crystals, more than a five-fold improvement (millimeter spatial resolution) can be achieved both laterally and in event depth. At the core of the technique is the requirement to resolve the shadow from an optical mask placed in the scintillation light path between the crystal and the readout. In this paper, experimental results are presented that demonstrate the overall concept using a 1D shadow mask, a thin-scintillator crystal and a light pipe of varying thickness to emulate a 2.2-cm-thick crystal. Spatial resolutions of 1 mm in both depth and transverse to the readout face are obtained over most of the crystal depth.

  1. Event Localization in Bulk Scintillator Crystals Using Coded Apertures

    SciTech Connect

    Ziock, Klaus-Peter; Braverman, Joshua B.; Fabris, Lorenzo; Harrison, Mark J.; Hornback, Donald Eric; Newby, Jason

    2015-06-01

    The localization of radiation interactions in bulk scintillators is generally limited by the size of the light distribution at the readout surface of the crystal/light-pipe system. By finding the centroid of the light spot, which is typically of order centimeters across, practical single-event localization is limited to ~2 mm/cm of crystal thickness. Similar resolution can also be achieved for the depth of interaction by measuring the size of the light spot. Through the use of near-field coded-aperture techniques applied to the scintillation light, light transport simulations show that for 3-cm-thick crystals, more than a five-fold improvement (millimeter spatial resolution) can be achieved both laterally and in event depth. At the core of the technique is the requirement to resolve the shadow from an optical mask placed in the scintillation light path between the crystal and the readout. In this paper, experimental results are presented that demonstrate the overall concept using a 1D shadow mask, a thin-scintillator crystal and a light pipe of varying thickness to emulate a 2.2-cm-thick crystal. Spatial resolutions of ~ 1 mm in both depth and transverse to the readout face are obtained over most of the crystal depth.

  2. X-ray Scintillation in Lead Halide Perovskite Crystals

    PubMed Central

    Birowosuto, M. D.; Cortecchia, D.; Drozdowski, W.; Brylew, K.; Lachmanski, W.; Bruno, A.; Soci, C.

    2016-01-01

    Current technologies for X-ray detection rely on scintillation from expensive inorganic crystals grown at high-temperature, which so far has hindered the development of large-area scintillator arrays. Thanks to the presence of heavy atoms, solution-grown hybrid lead halide perovskite single crystals exhibit short X-ray absorption length and excellent detection efficiency. Here we compare X-ray scintillator characteristics of three-dimensional (3D) MAPbI3 and MAPbBr3 and two-dimensional (2D) (EDBE)PbCl4 hybrid perovskite crystals. X-ray excited thermoluminescence measurements indicate the absence of deep traps and a very small density of shallow trap states, which lessens after-glow effects. All perovskite single crystals exhibit high X-ray excited luminescence yields of >120,000 photons/MeV at low temperature. Although thermal quenching is significant at room temperature, the large exciton binding energy of 2D (EDBE)PbCl4 significantly reduces thermal effects compared to 3D perovskites, and moderate light yield of 9,000 photons/MeV can be achieved even at room temperature. This highlights the potential of 2D metal halide perovskites for large-area and low-cost scintillator devices for medical, security and scientific applications. PMID:27849019

  3. X-ray Scintillation in Lead Halide Perovskite Crystals

    NASA Astrophysics Data System (ADS)

    Birowosuto, M. D.; Cortecchia, D.; Drozdowski, W.; Brylew, K.; Lachmanski, W.; Bruno, A.; Soci, C.

    2016-11-01

    Current technologies for X-ray detection rely on scintillation from expensive inorganic crystals grown at high-temperature, which so far has hindered the development of large-area scintillator arrays. Thanks to the presence of heavy atoms, solution-grown hybrid lead halide perovskite single crystals exhibit short X-ray absorption length and excellent detection efficiency. Here we compare X-ray scintillator characteristics of three-dimensional (3D) MAPbI3 and MAPbBr3 and two-dimensional (2D) (EDBE)PbCl4 hybrid perovskite crystals. X-ray excited thermoluminescence measurements indicate the absence of deep traps and a very small density of shallow trap states, which lessens after-glow effects. All perovskite single crystals exhibit high X-ray excited luminescence yields of >120,000 photons/MeV at low temperature. Although thermal quenching is significant at room temperature, the large exciton binding energy of 2D (EDBE)PbCl4 significantly reduces thermal effects compared to 3D perovskites, and moderate light yield of 9,000 photons/MeV can be achieved even at room temperature. This highlights the potential of 2D metal halide perovskites for large-area and low-cost scintillator devices for medical, security and scientific applications.

  4. X-ray Scintillation in Lead Halide Perovskite Crystals.

    PubMed

    Birowosuto, M D; Cortecchia, D; Drozdowski, W; Brylew, K; Lachmanski, W; Bruno, A; Soci, C

    2016-11-16

    Current technologies for X-ray detection rely on scintillation from expensive inorganic crystals grown at high-temperature, which so far has hindered the development of large-area scintillator arrays. Thanks to the presence of heavy atoms, solution-grown hybrid lead halide perovskite single crystals exhibit short X-ray absorption length and excellent detection efficiency. Here we compare X-ray scintillator characteristics of three-dimensional (3D) MAPbI3 and MAPbBr3 and two-dimensional (2D) (EDBE)PbCl4 hybrid perovskite crystals. X-ray excited thermoluminescence measurements indicate the absence of deep traps and a very small density of shallow trap states, which lessens after-glow effects. All perovskite single crystals exhibit high X-ray excited luminescence yields of >120,000 photons/MeV at low temperature. Although thermal quenching is significant at room temperature, the large exciton binding energy of 2D (EDBE)PbCl4 significantly reduces thermal effects compared to 3D perovskites, and moderate light yield of 9,000 photons/MeV can be achieved even at room temperature. This highlights the potential of 2D metal halide perovskites for large-area and low-cost scintillator devices for medical, security and scientific applications.

  5. Fast scintillation light from CaMoO4 crystals

    NASA Astrophysics Data System (ADS)

    Veresnikova, A. V.; Lubsandorzhiev, B. K.; Barabanov, I. R.; Grabmayr, P.; Greiner, D.; Jochum, J.; Knapp, M.; Oßwald, C.; Poleshuk, R. V.; Ritter, F.; Shaibonov, B. A. M.; Vyatchin, Y. E.; Meierhofer, G.

    2009-05-01

    We report the observation of multi-exponential scintillation light emission from a CaMoO4 crystal with slow and fast components after both α-particles or γ-quanta irradiation. The slow components with decay times of ˜5 and ˜15 μs produce the main contribution to the light yield. Whereas the fast components with ˜10-50 ns decay times observed for the first time with such a crystal at room temperature contribute <1% to the crystal total light yield.

  6. An analysis of side readouts of monolithic scintillation crystals

    NASA Astrophysics Data System (ADS)

    Li, Xin; Furenlid, Lars R.

    2016-10-01

    We have explored a method of using the side surfaces of a thin monolithic scintillation crystal for reading out scintillation photons. A Monte-Carlo simulation was carried out for an LYSO crystal of 50:8mmx50:8mmx3mm with 5 silicon photomultipliers attached on each of the four side surfaces. With 511 keV gamma-rays, X-Y spatial resolution of 2:10mm was predicted with an energy resolution of 9:0%. We also explored adding optical barriers to improve the X-Y spatial resolution, and an X-Y spatial resolution of 786um was predicted with an energy resolution of 9:2%. Multiple layers can be stacked together and readout channels can be combined. Depth-of- interaction information (DOI) can be directly read out. This method provides an attractive detector module design for positron emission tomography (PET).

  7. Improving scintillation crystals using muon tomography

    SciTech Connect

    Dowell, D.H.; Fineman, B.J.; Sandorfi, A.M.

    1987-01-01

    The cosmic ray muon scanning array provides information on NaI(T1) crystals using some 65,536 trajectories, each measuring the NaI(T1) response to high energy muons. With this information, it is possible to use established computer-aided-tomography techniques to deconvolute these integrated responses and produce a detailed picture of the detector's interior.

  8. Free carrier absorption in self-activated PbWO4 and Ce-doped Y3(Al0.25Ga0.75)3O12 and Gd3Al2Ga3O12 garnet scintillators

    NASA Astrophysics Data System (ADS)

    Auffray, E.; Korjik, M.; Lucchini, M. T.; Nargelas, S.; Sidletskiy, O.; Tamulaitis, G.; Tratsiak, Y.; Vaitkevičius, A.

    2016-08-01

    Nonequilibrium carrier dynamics in the scintillators prospective for fast timing in high energy physics and medical imaging applications was studied. The time-resolved free carrier absorption investigation was carried out to study the dynamics of nonequilibrium carriers in wide-band-gap scintillation materials: self-activated led tungstate (PbWO4, PWO) ant two garnet crystals, GAGG:Ce and YAGG:Ce. It was shown that free electrons appear in the conduction band of PWO and YAGG:Ce crystals within a sub-picosecond time scale, while the free holes in GAGG:Ce appear due to delocalization from Gd3+ ground states to the valence band within a few picoseconds after short-pulse excitation. The influence of Gd ions on the nonequilibrium carrier dynamics is discussed on the base of comparison the results of the free carrier absorption in GAGG:Ce containing gadolinium and in YAGG without Gd in the host lattice.

  9. Study of light transport inside scintillation crystals for PET detectors.

    PubMed

    Yang, Xin; Downie, Evan; Farrell, Thomas; Peng, Hao

    2013-04-07

    Scintillation crystal design is a critical component in positron emission tomography system development, which impacts a number of performance parameters including energy resolution, time resolution and spatial resolution. Our work aims to develop a generalized simulation tool to model the light transport inside scintillation crystals with good accuracy, taking into account surface treatments, reflectors, temporal dependence of scintillation decay, and comprehensive experimental validations. The simulation has been validated against both direct analytical calculation and experimental measurements. In this work, the studies were performed for a lutetium-yttrium oxyorthosilicate crystal of 3×3×20 mm(3) dimension coupled to a Hamamatsu silicon photomultiplier, with respect to light output, rise-time slope, energy resolution and time resolution. Four crystal surface treatment and reflector configurations were investigated: GroundMetal, GroundPaint, PolishMetal and PolishPaint. The experiments were performed to validate the Monte Carlo simulation results. The results indicate that the best time resolution (0.96±0.05 ns) and good energy resolution (10.6±0.4%) could be produced by using a polished surface with specular reflector, while the configuration of a polished surface with diffusive reflector produces the best energy resolution (10.2±0.9%). The results indicate that a polished surface with diffusive reflector achieves the best energy resolution (10.2±0.9%) for 511 keV high energy photons, and a polished surface with specular reflector achieves the best time resolution (0.96±0.05 ns) measured against a Hamamatsu fast photomultiplier tube. The ground surface treatment is not recommended for its inferior performance in terms of energy and time resolution. Possible explanations and future improvements to be made to the developed simulation tool are discussed.

  10. Crystal Identification in Stacked GAGG Scintillators for 4π Direction Sensitive Gamma-ray Imager

    NASA Astrophysics Data System (ADS)

    Fuwa, Yuta; Takahashi, Tone; Kawarabayashi, Jun; Tomita, Hideki; Matui, Daiki; Takada, Eiji; Iguchi, Tetsuo

    To identify two interaction points in stacked Ce:GAGG scintillators for Compton imaging, center of gravity with small area of the MA-PMT outputs, called small area center of gravity (SACG) method, was developed to reduce channel numbers of the MA-PMT. Both longitudinal position and energy resolutions of each scintillator rod by SACG method were evaluated in coincident events in 2 × 2 stacked Ce:GAGG scintillators. Crystal identification was successfully demonstrated in 16 × 16 stacked scintillators.

  11. Barium iodide and strontium iodide crystals andd scintillators implementing the same

    DOEpatents

    Payne, Stephen A; Cherepy, Nerine J; Hull, Giulia E; Drobshoff, Alexander D; Burger, Arnold

    2013-11-12

    In one embodiment, a material comprises a crystal comprising strontium iodide providing at least 50,000 photons per MeV. A scintillator radiation detector according to another embodiment includes a scintillator optic comprising europium-doped strontium iodide providing at least 50,000 photons per MeV. A scintillator radiation detector in yet another embodiment includes a scintillator optic comprising SrI.sub.2 and BaI.sub.2, wherein a ratio of SrI.sub.2 to BaI.sub.2 is in a range of between 0:1 A method for manufacturing a crystal suitable for use in a scintillator includes mixing strontium iodide-containing crystals with a source of Eu.sup.2+, heating the mixture above a melting point of the strontium iodide-containing crystals, and cooling the heated mixture near the seed crystal for growing a crystal. Additional materials, systems, and methods are presented.

  12. Effects of Packaging SrI2(Eu) Scintillator Crystals

    SciTech Connect

    Sturm, Benjamin; Cherepy, Nerine; Drury, Owen; Thelin, P; Fisher, S E; Payne, Stephen A.; Burger, Arnold; Boatner, Lynn A; Ramey, Joanne Oxendine; Shah, Kanai; Hawrami, Rastgo

    2011-01-01

    Recent renewed emphasis placed on gamma-ray detectors for national security purposes has motivated 13 researchers to identify and develop new scintillator materials capable of high energy resolution and 14 growable to large sizes. We have discovered that SrI2(Eu) has many desirable properties for gamma-ray 15 detection and spectroscopy, including high light yield of ~90,000 photons/MeV and excellent light yield 16 proportionality. Furthermore, we have demonstrated growth of crack-free 2 diameter boules. We 17 have measured <2.7% FWHM at 662 keV with small detectors (<1 cm3) in direct contact with a 18 photomultiplier tube, and ~3% resolution at 662 keV is obtained for 1 in3 crystals. Due to the 19 hygroscopic nature of SrI2(Eu), proper packaging is required for field use. This work describes a 20 systematic study performed to determine the key factors in the packaging process to optimize 21 performance. These factors include proper polishing of the surface, the geometry of the crystal, 22 reflector materials and windows. A technique based on use of a collimated Cs-137 source was developed 23 to examine light collection uniformity. Employing this technique, we found that when the crystal is 24 packaged properly, the variance in the pulse height at 662 keV from events near the bottom of the 25 crystal compared to those near the top of the crystal could be reduced to <1%. This paper describes the 26 design and engineering of our detector package in order to improve energy resolution of 1 in3-scale 27 SrI2(Eu) crystals.

  13. Scintillation properties of SrF2 and SrF2-Ce3+ crystals

    NASA Astrophysics Data System (ADS)

    Shendrik, R. Yu.; Radzhabov, E. A.; Nepomnyashchikh, A. I.

    2013-07-01

    This Letter presents the results of measuring scintillation properties of pure SrF2 crystals and crystals activated by various concentrations of Ce3+ ions. The light yield of these materials is compared to that of the known scintillators NaI-Tl and CaF2-Eu2+. Strontium fluoride crystals activated with Ce3+ ions are found to be characterized by high light yield and to be promising materials for use in scintillation detectors employed for γ-ray well logging.

  14. Comparative study of ceramic and single crystal Ce:GAGG scintillator

    NASA Astrophysics Data System (ADS)

    Yanagida, Takayuki; Kamada, Kei; Fujimoto, Yutaka; Yagi, Hideki; Yanagitani, Takagimi

    2013-10-01

    Recent study revealed that single crystal Ce:Gd3(Al,Ga)5O12 (Ce:GAGG) showed good scintillation response under γ-ray exposure. We discover here that ceramic Ce:GAGG scintillator exhibited better performance than the single crystal counterpart. We developed Ce 1% doped ceramic and single crystal GAGG scintillators with 1 mm thick and compared their properties. In radioluminescence spectra, they showed intense emission peaking at 530 nm due to Ce3+ 5d-4f transition. The 137Cs γ-ray induced light yields of ceramic and single crystal resulted 70 000 ph/MeV and 46 000 ph/MeV with primary decay times of 165 and 143 ns, respectively. At present, the observed light yield was the brightest in oxide scintillators.

  15. Digital silicon photomultiplier readout of a new fast and bright scintillation crystal (Ce:GFAG)

    NASA Astrophysics Data System (ADS)

    Lee, Yong-Seok; Leem, Hyun-Tae; Yamamoto, Seiichi; Choi, Yong; Kamada, Kei; Yoshikawa, Akira; Park, Sang-Geon; Yeom, Jung-Yeol

    2016-10-01

    A new Gadolinium Fine Aluminum Gallate (Ce:GFAG) scintillation crystal with both high energy resolution and fast timing properties has successfully been grown. Compared to Gd3Al2Ga3O12 (Ce:GAGG), this new inorganic scintillation crystal has a high luminosity similar to and a faster decay time. In this paper, we report on the timing and energy performance results of the new GFAG scintillation crystal read out with digital silicon photomultipliers (dSiPM) for positron emission tomography (PET) application. The best coincidence resolving time (FWHM) of polished 3×3×5 mm3 crystals was 223±6 ps for GFAG crystals compared to 396±28 ps for GAGG crystals and 131±3 ps for LYSO crystals respectively. An energy resolution (511 keV peak of Na-22) of 10.9±0.2% was attained with GFAG coupled to dSiPM after correcting for saturation effect, compared to 9.5±0.3% for Ce:GAGG crystals and 11.9±0.4% for LYSO crystals respectively. It is expected that this new scintillator may be competitive in terms of overall properties such as energy resolution, timing resolution and growing (raw material) cost, compared to existing scintillators for positron emission tomography (PET).

  16. Crystal growth and scintillation properties of Lu substituted CeBr3 single crystals

    NASA Astrophysics Data System (ADS)

    Ito, Tomoki; Yokota, Yuui; Kurosawa, Shunsuke; Král, Robert; Kamada, Kei; Pejchal, Jan; Ohashi, Yuji; Yoshikawa, Akira

    2016-10-01

    We grew Lu-substituted CeBr3 [(Ce1-xLux)Br3] crystals by a modified micro-pulling-down method to increase the effective atomic number and to investigate effects of the Lu substitution on the crystal growth, phase generation, chemical composition, and optical and scintillation properties. The (Ce1-xLux)Br3 crystals with x=0 and 0.01 had high transparency while the milky parts were generated in the crystals with x=0.05 and 0.20. By the analysis of chemical composition, the estimated Zeff increased to 47.9. On the other hand, the light yields were systematically decreased and decay times were increased with increasing Lu concentration.

  17. A crystal identification method for monolithic phoswich detectors based on scintillation light distribution

    NASA Astrophysics Data System (ADS)

    Preziosi, E.; Pani, R.; Trigila, C.; Polito, C.; Bettiol, M.; Borrazzo, C.; Cinti, M. N.; Fabbri, A.; Pellegrini, R.; Pani, R.

    2016-12-01

    Phoswich detectors based on scintillation crystals are widely diffused for both PET and SPECT applications. In order to separate the signals arising from different layers many methods have been proposed in literature. Separation of the layers commonly relies on time discrimination or pulse height discrimination. In this work, by means of experimental measurement on a phoswich detector based on Lanthanum Bromide and Lutetium Fine Silicate monolithic crystals, a novel method allowing to separate signals coming from different layers has been evaluated. The main feature of this method, specifically developed for phoswich based on monolithic scintillation crystals, is the discrimination capability based on the scintillation light distribution shape. For this reason, the findings that will be shown could be easily extended to whatever combination of scintillator, independently from their decay time or light yield.

  18. Barium iodide and strontium iodide crystals and scintillators implementing the same

    DOEpatents

    Payne, Stephen A.; Cherepy, Nerine J.; Hull, Giulia E.; Drobshoff, Alexander D.; Burger, Arnold

    2016-11-29

    In one embodiment, a material comprises a crystal comprising strontium iodide providing at least 50,000 photons per MeV, where the strontium iodide material is characterized by a volume not less than 1 cm.sup.3. In another embodiment, a scintillator optic includes europium-doped strontium iodide providing at least 50,000 photons per MeV, where the europium in the crystal is primarily Eu.sup.2+, and the europium is present in an amount greater than about 1.6%. A scintillator radiation detector in yet another embodiment includes a scintillator optic comprising SrI.sub.2 and BaI.sub.2, where a ratio of SrI.sub.2 to BaI.sub.2 is in a range of between 0:1 and 1.0, the scintillator optic is a crystal that provides at least 50,000 scintillation photons per MeV and energy resolution of less than about 5% at 662 keV, and the crystal has a volume of 1 cm.sup.3 or more; the scintillator optic contains more than about 2% europium.

  19. Growth and scintillation properties of 3 in. diameter Ce doped Gd3Ga3Al2O12 scintillation single crystal

    NASA Astrophysics Data System (ADS)

    Kamada, Kei; Shoji, Yasuhiro; Kochurikhin, Vladimir V.; Okumura, Satoshi; Yamamoto, Seiichi; Nagura, Aya; Yeom, Jung Yeol; Kurosawa, Shunsuke; Yokota, Yuui; Ohashi, Yuji; Nikl, Martin; Yoshikawa, Akira

    2016-10-01

    The 3 in. size Ce1%:Gd3Al2Ga3O12 single crystals were prepared by the Czochralski (Cz) method. Optical constants were measured. Chemical composition analysis and uniformity of scintillation decay and light yield along growth direction were evaluated. The timing resolution measurement for a pair of 3 mm×3 mm×3 mm size Ce:GAGG scintillator crystals was performed using Si-PMs.

  20. Crystal growth of Yb 3+-doped oxide single crystals for scintillator application

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Akira; Nikl, Martin; Ogino, Hiraku; Lee, Jong-Ho; Fukuda, Tsuguo

    2003-03-01

    Long emission wavelength scintillators are strongly required from the viewpoint of the practical use of silicon photo-diode, which has higher resolution with lower cost compared with photo-multipllier. Among the various scintillator emission centers, we regard emission from Yb 3+ charge-transitions state (CTS) as a candidate. In order to investigate proper hosts for Yb 3+ CTS, the yttrium gallium garnet host and lutetium aluminum garnet host were studied. Transparent and crack-free heavily Yb-doped YGG, i.e. {Y 1- xYb x} 3[Ga] 2(Ga) 3O 12 (Yb: YGG, x=0.15, 0.5, 1.0) and heavily Yb-doped LuAG, i.e. {Lu 1- xYb x} 3[Al] 2(Al) 3O 12 (Yb: LuAG, x=0.15, 0.5, 1.0) single crystals could be grown by the Modified Pulling Down method with <1 1 1> orientation. Emission, excitation spectra and decay kinetics were measured for these crystals. The CT transition of Yb 3+ in the yttrium gallium garnet host was discussed compared with the Yb 3+ one in the lutetium aluminum garnet host.

  1. Characterization of BaCl 2 scintillation crystal at low temperature

    NASA Astrophysics Data System (ADS)

    Kim, M. J.; Kim, H. J.; Park, H.; Kim, Sunghwan; Kim, Jung-in

    2011-03-01

    A BaCl 2 scintillation crystal was grown by the Czochralski method. The grown crystal was cut to a size of 10×10×5 mm 3. The scintillation properties of the crystal such as pulse height spectra, energy resolution, and fluorescence decay time were measured with a 137Cs (662 keV) γ-ray source at room temperature. We measured the temperature dependence of the scintillation light yield and decay time with a bi-alkali photomultiplier tube for the BaCl 2 crystal. The BaCl 2 crystal was cooled down with compressed helium gas from room temperature to 10 K. We measured the light yield and decay time changes of the BaCl 2 crystal from 10 K to room temperature. The light yield of the BaCl 2 at 200 K was four times higher than that at room temperature. The decay time increases as temperature decreases. The BaCl 2 scintillation crystal has a low light yield but a fast decay time so that it can be a calorimeter candidate for high energy physics experiments.

  2. Comparative study of intrinsic luminescence in undoped transparent ceramic and single crystal garnet scintillators

    NASA Astrophysics Data System (ADS)

    Fujimoto, Yutaka; Yanagida, Takayuki; Yagi, Hideki; Yanagidani, Takagimi; Chani, Valery

    2014-10-01

    Scintillation properties associated with intrinsic lattice defects of undoped Y3A5O12 (YAG) and Lu3A5O12 (LuAG) transparent ceramics and single crystals are compared. The ceramics excited with X-ray demonstrated relatively low emission intensity when compared with that of the single crystals. Decay times of the ceramics and the single crystals were similar. These parameters were approximately 430 ns (YAG ceramic), 460 ns (YAG single crystal), 30 ns and 1090 ns (LuAG ceramic), and 25 ns and 970 ns (LuAG single crystal). According to the pulse height spectra recorded under 137Cs gamma-ray irradiation, the scintillation light yield of the both ceramics were about 2950 ± 290 ph/MeV. However, the single crystals had greater kight yield of about about 14,300 ± 1430 ph/MeV for YAG and 8350 ± 830 ph/MeV for LuAG.

  3. A region segmentation based algorithm for building a crystal position lookup table in a scintillation detector

    NASA Astrophysics Data System (ADS)

    Wang, Hai-Peng; Yun, Ming-Kai; Liu, Shuang-Quan; Fan, Xin; Cao, Xue-Xiang; Chai, Pei; Shan, Bao-Ci

    2015-03-01

    In a scintillation detector, scintillation crystals are typically made into a 2-dimensional modular array. The location of incident gamma-ray needs be calibrated due to spatial response nonlinearity. Generally, position histograms-the characteristic flood response of scintillation detectors-are used for position calibration. In this paper, a position calibration method based on a crystal position lookup table which maps the inaccurate location calculated by Anger logic to the exact hitting crystal position has been proposed. Firstly, the position histogram is preprocessed, such as noise reduction and image enhancement. Then the processed position histogram is segmented into disconnected regions, and crystal marking points are labeled by finding the centroids of regions. Finally, crystal boundaries are determined and the crystal position lookup table is generated. The scheme is evaluated by the whole-body positron emission tomography (PET) scanner and breast dedicated single photon emission computed tomography scanner developed by the Institute of High Energy Physics, Chinese Academy of Sciences. The results demonstrate that the algorithm is accurate, efficient, robust and applicable to any configurations of scintillation detector. Supported by National Natural Science Foundation of China (81101175) and XIE Jia-Lin Foundation of Institute of High Energy Physics (Y3546360U2)

  4. Study of the growth atmosphere effect on optical and scintillation characteristics of large CsI(TI) crystals

    NASA Astrophysics Data System (ADS)

    Panova, A. N.; Goriletsky, V. I.; Grinyova, T. B.; Shakhova, K. V.; Vinograd, E. L.

    1999-03-01

    In contrast to the traditional growth method of large scintillation alkali halide crystals - in an inert atmosphere, CsI(TI) crystals have been grown in CO 2 atmosphere favoring changes of their impurity composition. Absorption and scintillation characteristics of crystals obtained have been studied in comparison to those grown in the inert gas medium. Effect of different radiation doses on variations in optical and scintillation characteristics has been studied for CsI(TI) crystals grown by various techniques. CsI(TI) crystals grown in CO 2 atmosphere are found to exhibit a higher radiation resistance and a faster restoration of their basic characteristics.

  5. Modified timing characteristic of a scintillation detection system with photonic crystal structures.

    PubMed

    Liu, Jinliang; Liu, Bo; Zhu, Zhichao; Chen, Liang; Hu, Jing; Xu, Mengxuan; Cheng, Chuanwei; Ouyang, Xiaoping; Zhang, Zhongbing; Ruan, Jinlu; He, Shiyi; Liu, Linyue; Gu, Mu; Chen, Hong

    2017-03-01

    It is intuitively expected that an enhanced light extraction of a scintillator can be easily achieved by photonic crystal structures. Here, we demonstrate a modified timing characteristic for a detection system induced by enhanced light extraction with photonic crystal structures. Such improvement is due to the enhanced light extraction which can be clearly proven by the independent measurements of the light output and the timing resolution. The present investigation is advantageous to promote the development of a scintillation detection system performance based on the time-of-flight measurement.

  6. Fast ultradense GdTa1-xNbxO4 scintillator crystals

    NASA Astrophysics Data System (ADS)

    Voloshyna, Olesia; Gerasymov, Iaroslav; Sidletskiy, Oleg; Kurtsev, Daniil; Gorbacheva, Tatyana; Hubenko, Kateryna; Boiaryntseva, Ianina; Ivanov, Alexey; Spassky, Dmitry; Omelkov, Sergey; Belsky, Andrei

    2017-04-01

    Single crystals of GdTaO4 and GdTa0.8Nb0.2O4 were grown by the Czochralski technique, and their luminescent and scintillation properties were studied. Both crystals demonstrate fast emission with decay time around 10-8 s. Meanwhile, in GdTaO4 the fast decay is accompanied by a huge build-up with the decay time around 1 μs, while in the mixed crystal the contribution of slow components is negligible. UV- and X-ray excited luminescence, curves of thermostimulated luminescence and absolute light yields of crystals are presented as well. GdTa0.8Nb0.2O4 crystal is shown to be an ultradense (8.37 g/cm3) and fast (shortest component decay time 17 ns) scintillator with a high stopping power.

  7. Formation of light-reflecting powder shells for scintillation crystals with a complicated shape

    SciTech Connect

    Mel`nik, V.I.; Grinev, B.V.

    1995-10-01

    Technical means for mechanized formation of light-reflecting powder shells of scintillation crystals with a complicated shape that is close to conical are unknown at present. Below, we suggest a design for such technical facilities, a technology for assembling detectors with their aid, and the selection of the operational parameters of the assembly.

  8. Scintillation properties of semiconducting 6LiInSe2 crystals to ionizing radiation

    NASA Astrophysics Data System (ADS)

    Wiggins, Brenden; Groza, Michael; Tupitsyn, Eugene; Lukosi, Eric; Stassun, Keivan; Burger, Arnold; Stowe, Ashley

    2015-11-01

    6LiInSe2 has gained attention recently as a semiconducting thermal neutron detector. As presented herein, the chalcogenide compound semiconductor also detects incident neutrons via scintillation, making 6LiInSe2 the only lithium containing semiconductor to respond to neutrons via both detection mechanisms. Both yellow and red crystals, which appear in the literature, were investigated. Only the yellow crystal responded favorably to ionizing radiation, similar to the semiconducting operation utilizing electrodes. The obtained light yield for yellow crystals is 4400 photons/MeV, referenced to Bi4Ge3O12 (BGO).The estimated thermal neutron light yield was 21,000 photons/thermal neutron. The two measured decay time components were found to be 31±1 ns (49%) and 143±9 ns (51%).This crystal provides efficient, robust detection of neutrons via scintillation with respectable light yield and rapid response, enabling its use for a broad array of neutron detection applications.

  9. Defect Engineering in SrI2:Eu2+ Single Crystal Scintillators

    DOE PAGES

    Wu, Yuntao; Boatner, Lynn A.; Lindsey, Adam C.; ...

    2015-06-23

    Eu2+-activated strontium iodide is an excellent single crystal scintillator used for gamma-ray detection and significant effort is currently focused on the development of large-scale crystal growth techniques. A new approach of molten-salt pumping or so-called melt aging was recently applied to optimize the crystal quality and scintillation performance. Nevertheless, a detailed understanding of the underlying mechanism of this technique is still lacking. The main purpose of this paper is to conduct an in-depth study of the interplay between microstructure, trap centers and scintillation efficiency after melt aging treatment. Three SrI2:2 mol% Eu2+ single crystals with 16 mm diameter were grownmore » using the Bridgman method under identical growth conditions with the exception of the melt aging time (e.g. 0, 24 and 72 hours). Using energy-dispersive X-ray spectroscopy, it is found that the matrix composition of the finished crystal after melt aging treatment approaches the stoichiometric composition. The mechanism responsible for the formation of secondary phase inclusions in melt-aged SrI2:Eu2+ is discussed. Simultaneous improvement in light yield, energy resolution, scintillation decay-time and afterglow is achieved in melt-aged SrI2:Eu2+. The correlation between performance improvement and defect structure is addressed. The results of this paper lead to a better understanding of the effects of defect engineering in control and optimization of metal halide scintillators using the melt aging technique.« less

  10. Precision machining and polishing of scintillating crystals for large calorimeters and hodoscopes

    SciTech Connect

    Wuest, C.R.; Fuchs, B.A.

    1993-05-01

    New machining and polishing techniques have been developed for large barium fluoride scintillating crystals that provide crystalline surfaces without sub-surface damage or deformation as verified by Atomic Force Microscopy (AFM) and Rutherford Back-scattering (RBS) analyses. Surface roughness of about 10--20 angstroms and sub-micron mechanical tolerances have been demonstrated on large crystal samples. Mass production techniques have also been developed for machining and polishing up to five 50 cm long crystals at one time. We present this technology along with surface studies of barium fluoride crystals polished with this technique. This technology is applicable for a number of new crystal detectors proposed at Colliders including the Barium Fluoride Electromagnetic Calorimeter at SSC, the Crystal Clear Collaboration`s cerium fluoride calorimeter at LHC, and the KTeV and PHENIX scintillating hodoscopes at Fermilab, and RHIC, respectively. Lawrence Livermore National Laboratory (LLNL) has an active program of study on barium fluoride scintillating crystals for the Barium Fluoride Electromagnetic Calorimeter Collaboration and cerium fluoride and lead fluoride for the Crystal Clear Collaboration. This program has resulted in a number of significant improvements in the mechanical processing, polishing and coating of fluoride crystals. Techniques have been developed using diamond-loaded pitch lapping that can produce 15 angstrom RMS surface finishes over large areas. Also, special polishing fixtures have been designed based on mounting technology developed for the 1.1 m diameter optics used in LLNL`s Nova Laser. These fixtures allow as many as five 25--50 cm long crystals to be polished and lapped at the same time with tolerances satisfying the stringent requirements of crystal calorimeters. We also discuss results on coating barium fluoride with UV reflective layers of magnesium fluoride and aluminum.

  11. Effects of increasing size and changing europium activator concentration in KCaI3 scintillator crystals

    NASA Astrophysics Data System (ADS)

    Lindsey, Adam C.; Zhuravleva, Mariya; Wu, Yuntao; Stand, Luis; Loyd, Matthew; Gokhale, Sasmit; Koschan, Merry; Melcher, Charles L.

    2016-09-01

    KCaI3:Eu crystals have been identified as very promising for use in spectroscopic detector applications related to nuclear nonproliferation and domestic security efforts. Initial studies have shown for small crystals a few mm3 in size with 3% europium dopant concentration, a high light yield of >70,000 ph/MeV and energy resolution of ≈3% at 662 keV is attainable which is comparable with the highest performance scintillators discovered. In this work, single crystals of KCaI3 with a range of Eu2+ doping between 0 and 5 at% substituting for Ca2+ were grown at 22 mm diameter and their performance for gamma-ray spectroscopy studied. Comparisons among crystals approximately Ø22 mm×22 mm (8.4 cm3 or ≈0.5 in3) provide a more accurate understanding of how scintillation performance changes with Eu doping and increased crystal size. KCaI3 in the undoped form is shown to be a highly efficient intrinsic scintillator with a defect-related emission at 404 nm which coexists with the Eu2+ 5d-4f emission in low dopant concentrations and is completely re-absorbed in more heavily doped crystals. For larger crystals, effects from self-absorption due to Eu activation become more evident by a near doubling of decay time for 0.5 in3 crystals as the activator is increased from 0.5 to 5.0 at% Eu. Comparisons of pulse-height spectra obtained for Ø22 mm×22 mm cylinders with varying Eu concentration suggests best performance is achieved using lower Eu additions closer to 0.5-1.0 at%. Using a modified crystal packaging featuring an offset reflector geometry, 0.5 in3 crystals of KCaI3:Eu can attain under 4% energy resolution at 662 keV.

  12. Cesium hafnium chloride: A high light yield, non-hygroscopic cubic crystal scintillator for gamma spectroscopy

    SciTech Connect

    Burger, Arnold; Rowe, Emmanuel; Groza, Michael; Morales Figueroa, Kristle; Cherepy, Nerine J.; Beck, Patrick R.; Hunter, Steven; Payne, Stephen A.

    2015-10-05

    We report on the scintillation properties of Cs{sub 2}HfCl{sub 6} (cesium hafnium chloride or CHC) as an example of a little-known class of non-hygroscopic compounds having the generic cubic crystal structure of K{sub 2}PtCl{sub 6}. The crystals are easily growable from the melt using the Bridgman method with minimal precursor treatments or purification. CHC scintillation is centered at 400 nm, with a principal decay time of 4.37 μs and a light yield of up to 54 000 photons/MeV when measured using a silicon CCD photodetector. The light yield is the highest ever reported for an undoped crystal, and CHC also exhibits excellent light yield nonproportionality. These desirable properties allowed us to build and test CHC gamma-ray spectrometers providing energy resolution of 3.3% at 662 keV.

  13. R and D of crystal scintillators from enriched isotopes for high sensitivity double β decay experiments

    SciTech Connect

    Danevich, F. A.

    2013-12-30

    Experiments to search for neutrinoless double beta decay enters to a new phase when a sensitivity on the level of T{sub 1/2}∼10{sup 26}−10{sup 28} yr is required. Scintillating low temperature detectors possess important properties required for high-sensitivity double beta decay experiments: presence of elements of interest, high energy resolution and detection efficiency, low level of background thanks to excellent particle discrimination ability. High concentration of isotope of interest and as low as possible radioactive contamination are important requirements to crystal scintillators. Other crucial issues are maximal output of detectors and minimal loss of enriched materials. Prospects of several scintillation materials, enriched in isotopes promising for double beta decay experiments, are discussed.

  14. Investigation of the unique degradation phenomenon observed in CsSrBr3: Eu 5% scintillator crystals

    NASA Astrophysics Data System (ADS)

    Gokhale, S. S.; Loyd, M.; Stand, L.; Lindsey, A.; Swider, S.; Zhuravleva, M.; Melcher, C. L.

    2016-10-01

    CsSrBr3: Eu 5% is a promising compound scintillator for radiation detection and imaging applications. Light output and energy resolution measured for a crystal of volume 5×5×5 mm3 were 55,000±2000 ph/MeV and 5.6% at 662 keV respectively which is a significant improvement over previous reports. The hygroscopicity of the compound and the tendency of the scintillator crystals to degrade when exposed to the atmosphere necessitate the proper encapsulation of the crystals. It was observed that unlike other hygroscopic scintillator crystals CsSrBr3 undergoes a unique degradation while encapsulated in mineral oil. The light output of the crystal decreases over time, but there is no visually observed physical degradation of the crystal. This degradation is a reversible process wherein a degraded crystal can be subjected to annealing in vacuum in order to restore its original performance.

  15. Advances in the growth of alkaline-earth halide single crystals for scintillator detectors

    SciTech Connect

    Boatner, Lynn A; Ramey, Joanne Oxendine; Kolopus, James A; Neal, John S; Cherepy, Nerine; Payne, Stephen A.; Beck, P; Burger, Arnold; Rowe, E; Bhattacharya, P.

    2014-01-01

    Alkaline-earth scintillators such as strontium iodide and other alkaline-earth halides activated with divalent europium represent some of the most efficient and highest energy resolution scintillators for use as gamma-ray detectors in a wide range of applications. These applications include the areas of nuclear nonproliferation, homeland security, the detection of undeclared nuclear material, nuclear physics and materials science, medical diagnostics, space physics, high energy physics, and radiation monitoring systems for first responders, police, and fire/rescue personnel. Recent advances in the growth of large single crystals of these scintillator materials hold the promise of higher crystal yields and significantly lower detector production costs. In the present work, we describe new processing protocols that, when combined with our molten salt filtration methods, have led to advances in achieving a significant reduction of cracking effects during the growth of single crystals of SrI2:Eu2+. In particular, we have found that extended pumping on the molten crystal-growth charge under vacuum for time periods extending up to 48 hours is generally beneficial in compensating for variations in the alkaline-earth halide purity and stoichiometry of the materials as initially supplied by commercial sources. These melt-pumping and processing techniques are now being applied to the purification of CaI2:Eu2+ and some mixed-anion europium-doped alkaline-earth halides prior to single-crystal growth by means of the vertical Bridgman technique. The results of initial studies of the effects of aliovalent doping of SrI2:Eu2+ on the scintillation characteristics of this material are also described.

  16. Multi-ampoule Bridgman growth of halide scintillator crystals using the self-seeding method

    NASA Astrophysics Data System (ADS)

    Lindsey, Adam C.; Wu, Yuntao; Zhuravleva, Mariya; Loyd, Matthew; Koschan, Merry; Melcher, Charles L.

    2017-07-01

    We investigate the multi-ampoule growth at 25 mm diameter of ternary iodide single crystal scintillator KCaI3:Eu using the randomly oriented self-seeded Bridgman method. We compare scintillation performance between cubic inch scale crystals containing small variations of low nominal europium concentrations previously shown to balance light yield with self-absorption in the host crystal. Growth conditions were optimized in the developmental furnace and four 2 in3 KCaI3:Eu crystals were grown simultaneously producing a total of six 25 mm × 25 mm cylinders. Small variations in activator concentration did not result in significant performance differences among the six measured crystals. A range of energy resolutions of 3.5-4.7% at 662 keV was achieved, surpassing that of NaI:Tl crystals commonly used in spectroscopic detection applications. The function and basic design of the multi-ampoule furnace as well as the process of growing single crystals of KCaI3 is included here.

  17. Crystal growth and scintillation properties of undoped and Ce3+-doped GdI3 crystals

    NASA Astrophysics Data System (ADS)

    Ye, Le; Li, Huanying; Wang, Chao; Shi, Jian; Chen, Xiaofeng; Wang, Zhongqing; Huang, Yuefeng; Xu, Jiayue; Ren, Guohao

    2017-02-01

    The growth and scintillation properties of undoped and Ce3+-doped GdI3 crystals were reported in this paper. These GdI3:χ%Ce (χ = 0, 1, 2) crystals were grown by the vertical Bridgman growth technique in evacuated quartz crucibles. X-ray excited optical luminescence spectra of GdI3:Ce exhibit a broad emission band (450 nm-650 nm) peaking at 520 nm corresponding to 5d1→4f1 transition of Ce3+ while the undoped GdI3 crystal consists of a broad band (400 nm-600 nm) and several sharp lines peaking at 462 nm, 482 nm, 492 nm, 549 nm, 579 nm owing to the impurities ions and defects. The excitation spectra of Ce3+ doped GdI3 consist of two broad bands between 300 nm and 500 nm corresponding to 4f1→5d1 absorption of Ce3+. The other absorption peaking at 262 nm in the spectrum of GdI3:2%Ce is assigned to band-to-band exciton transition. The excitation spectrum of undoped GdI3 contains a flat absorption band from 330 to 370 nm and a broad band between 390 and 450 nm peaking at 414 nm corresponding to the absorption of the unintentionally doped Ce3+, Dy3+, Ho3+ impurities and other defects. The emission spectrum of undoped GdI3 under 332 nm excitation has the identical line peaks with the spectrum measured under X-ray excitation. The emission spectra of GdI3:2%Ce and GdI3:1%Ce show a broad band in the range of 450-750 nm with the maximum at 550 nm corresponding to 5d1→4f1 transitions of Ce3+ ion. The GdI3, GdI3:1%Ce and GdI3:2%Ce show fast principle decay time constant 73 ns, 69 ns and 58 ns respectively, besides, the undoped also shows a slow decay constant 325 ns which doesn't appear in Ce3+-doped GdI3 crystal. The energy resolutions of GdI3:χ%Ce (χ = 1, 2) measured at 662 KeV are about 3%-5% and the undoped GdI3 is 13.3%.

  18. Barium iodide and strontium iodide crystals and scintillators implementing the same

    DOEpatents

    Payne, Stephen A.; Cherepy, Nerine; Pedrini, Christian; Burger, Arnold

    2016-09-13

    In one embodiment, a crystal includes at least one metal halide; and an activator dopant comprising ytterbium. In another general embodiment, a scintillator optic includes: at least one metal halide doped with a plurality of activators, the plurality of activators comprising: a first activator comprising europium, and a second activator comprising ytterbium. In yet another general embodiment, a method for manufacturing a crystal suitable for use in a scintillator includes mixing one or more salts with a source of at least one dopant activator comprising ytterbium; heating the mixture above a melting point of the salt(s); and cooling the heated mixture to a temperature below the melting point of the salts. Additional materials, systems, and methods are presented.

  19. Luminescence and scintillation properties of Rb2HfCl6 crystals

    NASA Astrophysics Data System (ADS)

    Saeki, Keiichiro; Wakai, Yuki; Fujimoto, Yutaka; Koshimizu, Masanori; Yanagida, Takayuki; Nakauchi, Daisuke; Asai, Keisuke

    2016-11-01

    We developed a scintillator based on a Rb2HfCl6 crystal as a ternary halide crystal with intrinsic luminescence. In the photoluminescence spectra, two emission bands are observed at 383 and 434 nm. The 434 nm emission band for Rb2HfCl6 may be attributed to [HfCl6]2- complex ion or [ZrCl6]2- impurity, since the Rb2HfCl6 contained Zr as impurity at 0.62 mol %. The radioluminescence band is observed at 420 nm and can be attributed to the same origin as the photoluminescence band at 434 nm. The scintillation decay-time constants were 0.84 and 5.4 µs. The light yield was estimated to be 24,100 photons/MeV.

  20. Advances in the growth of alkaline-Earth halide single crystals for scintillator detectors

    NASA Astrophysics Data System (ADS)

    Boatner, L. A.; Ramey, J. O.; Kolopus, J. A.; Neal, J. S.; Cherepy, N. J.; Beck, P. R.; Payne, S. A.; Burger, A.; Rowe, E.; Bhattacharya, P.

    2014-09-01

    Alkaline-earth scintillators such as strontium iodide and other alkaline-earth halides activated with divalent europium represent some of the most efficient and highest energy resolution scintillators for use as gamma-ray detectors in a wide range of applications. These applications include the areas of nuclear nonproliferation, homeland security, the detection of undeclared nuclear material, nuclear physics and materials science, medical diagnostics, space physics, high energy physics, and radiation monitoring systems for first responders, police, and fire/rescue personnel. Recent advances in the growth of large single crystals of these scintillator materials hold the promise of higher crystal yields and significantly lower detector production costs. In the present work, we describe new processing protocols that, when combined with our molten salt filtration methods, have led to advances in achieving a significant reduction of cracking effects during the growth of single crystals of SrI2:Eu2+. In particular, we have found that extended pumping on the molten crystalgrowth charge under vacuum for time periods extending up to 48 hours is generally beneficial in compensating for variations in the alkaline-earth halide purity and stoichiometry of the materials as initially supplied by commercial sources. These melt-pumping and processing techniques are now being applied to the purification of CaI2:Eu2+ and some mixed-anion europium-doped alkaline-earth halides prior to single-crystal growth by means of the vertical Bridgman technique. The results of initial studies of the effects of aliovalent doping of SrI2:Eu2+ on the scintillation characteristics of this material are also described.

  1. The Characterization of Eu2+-Doped Mixed Alkaline-Earth Iodide Scintillator Crystals

    SciTech Connect

    Neal, John S; Boatner, Lynn A; Ramey, Joanne Oxendine; Wisniewski, D.; Kolopus, James A; Cherepy, Nerine; Payne, Stephen A.

    2011-01-01

    The high-performance inorganic scintillator, SrI2:Eu2+, when activated with divalent europium in the concentration range of 3 to 6%, has shown great promise for use in applications that require high-energy-resolution gamma-ray detection. We have recently grown and tested crystals in which other alkaline-earth ions have been partially substituted for Sr ions. Specifically, europium-doped single crystals have been grown in which up to 30 at % of the strontium ions have been substituted for either by barium, magnesium, or calcium ions. In the case of the strontium iodide scintillator host, a material that is characterized by an orthorhombic crystal structure, there are three other column IIA elements that are obvious choices for investigations whose purpose is to realize potential improvements in the performance of SrI2:Eu2+-based scintillators via the replacement of strontium ions with either Mg2+, Ca2+, or Ba2+. Light yields of up to 81,400 photons/MeV with an associated energy resolution of 3.7% (fwhm for 662 keV gamma-rays) have been observed in the case of a partial substitution of Ba2+ for Sr2+. The measured decay times ranged from 1.1 to 2.0 s, while the peak emission wavelengths ranged from 432 to 438 nm.

  2. Performance study of Philips digital silicon photomultiplier coupled to scintillating crystals

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Pizzichemi, M.; Auffray, E.; Lecoq, P.; Paganoni, M.

    2016-01-01

    Silicon photomultipliers (SiPMs) and scintillators are often arranged in the shape of arrays in Positron Emission Tomography (PET) systems. Digital SiPMs provide signal readout in single photon avalanche diode (SPAD) level. From the photon count rate measurement of each SPAD cell of digital SiPM, we found that the output scintillating photons distribute in an area larger than the scintillator physical coupling area. Taking advantage of the possibility to enable/disable individual cells of the digital SiPM, a group of Lutetium-yttrium oxyorthosilicate (LYSO) crystals with different dimensions coupled to a digital SiPM was used to study the influence of using different SiPM active area on the number of photons detected, energy resolution and coincidence time resolution (CTR). For the same crystal coupled to the digital SiPM, the larger the active area of digital SiPM, the higher the number of photons detected. The larger active area of the digital SiPM also results in a better energy resolution after saturation correction. The best energy resolution full width half maximum (FWHM) obtained for the 2 × 2 × 5 mm3, 2 × 2 × 10 mm3, 2 × 2 × 15 mm3, 2 × 2 × 20 mm3 LYSO crystals was 10.7%, 11.6%, 12.1%, 12.5%, respectively. For crystals with different cross sections coupled to the digital SiPM, we found that the larger the cross section of coupling area, the more photons were detected and thus a better energy resolution was obtained. The CTR of crystals fully wrapped with Teflon or without wrapping was measured by positioning two identical crystals facing each other. A larger area of digital SiPM improves the CTR and the CTR reaches the plateau when the active area is larger than 2.2 × 2.2 mm2 with both two configurations of wrapping. The best CTR value for the 2 × 2 × 5 mm3, 2 × 2 × 10 mm3, 2 × 2 × 15 mm3, 2 × 2 × 20 mm3 LYSO crystals was 128.9 ps, 148.4 ps, 171.6 ps, 177.9 ps, respectively. The measurements performed lead us to conclude that optimising the

  3. Luminescence and scintillation properties of Cs3BiCl6 crystals

    NASA Astrophysics Data System (ADS)

    Shimizu, Makoto; Koshimizu, Masanori; Fujimoto, Yutaka; Yanagida, Takayuki; Ono, Shingo; Asai, Keisuke

    2016-11-01

    The optical and scintillation properties of Cs3BiCl6 single crystals were characterized, and absorption properties were investigated for thin films. The thin films showed two absorption bands at ∼220 nm and 330 nm; these bands can be attributed to the 1A1g → 1T1u and 1A1g → 3T1u transitions of Bi3+ ions, respectively. A luminescence band was observed at ∼390 nm in the photoluminescence spectra; this band can be attributed to the 3T1u → 1A1g transition of Bi3+ ions. In the X-ray-induced radioluminescence spectrum, in addition to the luminescence band at 390 nm, another band was observed at 600-700 nm; this band was tentatively attributed to the radiative recombination of self-trapped excitons. The decay-time constants of photoluminescence and scintillation decay were of the order of nanoseconds. The scintillation light yield was 800 photons/MeV. The results indicate that Cs3BiCl6 has a fast scintillation decay and a relatively poor light yield.

  4. Complex defects in crystal scintillation materials and phosphors

    NASA Astrophysics Data System (ADS)

    Lisitsyn, V.; Lisitsyna, L.; Polisadova, E.

    2017-01-01

    The possibility of the existence of complex defects in pure and doped crystal phosphor discussed in work. The luminescent properties of mono- and nanocrystals of zinc tungstate, the powders of YAG with various compositions are studied. It is shown that the intrinsic defects, impurities, oxygen vacancies, the hydroxyl groups may be present in the structure of the complex defects (nanodefects). Nanodefects form during synthesis and have high efficiency of the transfer of excitation energy to the emission centres.

  5. Ionization and proton induced radiation damage in crystal scintillators (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Zhu, Ren-Yuan

    2016-09-01

    Crystal detectors have been used widely in high energy and nuclear physics experiments, medical instruments and homeland security applications. A crucial issue for crystal detectors to be used for future HEP experiments at the energy and intensity frontiers is radiation damage by ionization dose as well as charged and neutral hadrons. This paper reports recent investigations on radiation damage in various crystal scintillators. Irradiations up to 340 Mrad of ionization dose, 1E16 p/cm^2 fluence and 1016 n/cm2 fluence were carried out at the JPL total ionization dose facility and the Los Alamos Neutron Science Center, respectively. Results of these investigations show excellent radiation hardness of bright and fast LYSO crystals which may provide a stable detector in an extreme harsh radiation environment, such as the proposed HL-LHC.

  6. Development of a fast radiation detector based on barium fluoride scintillation crystal

    SciTech Connect

    Han, Hetong; Zhang, Zichuan; Weng, Xiufeng; Liu, Junhong; Zhang, Kan; Li, Gang; Guan, Xingyin

    2013-07-15

    Barium fluoride (BaF{sub 2}) is an inorganic scintillation material used for the detection of X/gamma radiation due to its relatively high density, equivalent atomic number, radiation hardness, and high luminescence. BaF{sub 2} has a potential capacity to be used in gamma ray timing experiments due to the prompt decay emission components. It is known that the light output from BaF{sub 2} has three decay components: two prompt of those at approximately 195 nm and 220 nm with a decay constant around 600-800 ps and a more intense, slow component at approximately 310 nm with a decay constant around 630 ns which hinders fast timing experiments. We report here the development of a fast radiation detector based on a BaF{sub 2} scintillation crystal employing a special optical filter device, a multiple reflection multi-path ultraviolet region short-wavelength pass light guides (MRMP-short pass filter) by using selective reflection technique, for which the intensity of the slow component is reduced to less than 1%. The methods used for this study provide a novel way to design radiation detector by utilizing scintillation crystal with several emission bands.

  7. Technical Scope of Work: Proton Induced Radiation Damage in Crystal Scintillators

    SciTech Connect

    Zhu, Ren-Yuan; Zhang, Liyuan; Yang, Fan; Ramberg, Eric; Nebel, Todd

    2014-03-11

    This is a technical scope of work (TSW) between the Fermi National Accelerator Laboratory (Fermilab) and the experimenters of California Institute of Technology who have committed to participate in beam tests to be carried out during the 2014 Fermilab Test Beam Facility program. The goal of this investigation is to understand the proton-induced radiation damage in candidate fast crystal scintillators for future HEP experiments. Degradations of the optical and scintillation properties, including emission and transmittance spectra, light output, decay time and light response uniformity, will be measured before and after each step of proton irradiation at Fermilab with a defined fluence. The irradiation will start with a fluence of 1010/cm2 and going up in four steps to 1013/cm2.

  8. FLUKA studies of hadron-irradiated scintillating crystals for calorimetry at the High-Luminosity LHC

    NASA Astrophysics Data System (ADS)

    Quittnat, Milena; CMS Collaboration

    2015-02-01

    Calorimetry at the High-Luminosity LHC (HL-LHC) will be performed in a harsh radiation environment with high hadron fluences. The upgraded CMS electromagnetic calorimeter design and suitable scintillating materials are a focus of current research. In this paper, first results using the Monte Carlo simulation program FLUKA are compared to measurements performed with proton-irradiated LYSO, YSO and cerium fluoride crystals. Based on these results, an extrapolation to the behavior of an electromagnetic sampling calorimeter, using one of the inorganic scintillators above as an active medium, is performed for the upgraded CMS experiment at the HL-LHC. Characteristic parameters such as the induced ambient dose, fluence spectra for different particle types and the residual nuclei are studied, and the suitability of these materials for a future calorimeter is surveyed. Particular attention is given to the creation of isotopes in an LYSO-tungsten calorimeter that might contribute a prohibitive background to the measured signal.

  9. Kinetic and scintillation characteristics of CsI(Na) crystals grown under melt mixing

    NASA Astrophysics Data System (ADS)

    Goriletsky, V. I.; Grinyov, B. V.; Panova, A. M.; Shakhova, K. V.; Vinograd, E. L.; Korsunov, S. P.

    1999-10-01

    The effect of activator concentration on the γ-scintillation pulse shape, the light yield upon excitation with γ-rays and α-particles as well as the energy resolution, has been investigated for CsI(Na) crystals. The crystals were grown with a homogeneous activator distribution. Based on the concentration dependence of the α-particle light yield the number of activator emission centres in the crystals has been concluded to increase with concentration up to 2.5 × 10-2 mol% of NaI. Therefore, the maximum yield of γ-scintillation at ≈9 × 10-3 mol% NaI is due to a sufficient number of emission centres at the given ionization density. It is shown that the decay time can be reduced from 630 to 570 ns without change of the crystal spectrometric quality, and that it may be further reduced, in principle, down to values close to the decay time for intracenter excitation.

  10. Crystal growth and scintillation characterizations of Tl2LiYCl6: Ce3+

    NASA Astrophysics Data System (ADS)

    Rooh, Gul; Kim, H. J.; Park, H.; Kim, Sunghwan

    2017-02-01

    Single crystals of Tl2LiYCl6 with different mole% of Ce-concentration (0.5 and 5 mol%) were presented. This material belongs to Chloro-elpasolite crystal family and was grown by two zone vertical Bridgman technique. X-ray diffraction pattern of the Tl2LiYCl6 single crystal was measured. X-ray diffraction analysis confirmed tetragonal crystal structure. The melting point of the sample was measured by DSC. Typical Ce3+ ion emission spectra were observed when samples were excited by an X-ray source at room temperature. The observed emission spectra were located between 350 nm and 530 nm wavelength range and peaking around 430 nm. Pulse height spectra of the samples under 662 keV γ-rays excitation shows improvement in energy resolution with the increase of Ce-concentration in the host lattice. The energy resolutions were obtained to be 10.6% and 7.2% (FWHM) for 0.5% and 5% Ce3+ concentration, respectively. Under γ-ray excitation, a maximum light yield of 23,800±2400 ph/MeV was observed for 5% Ce-concentration. Studied samples of Tl2LiYCl6: Ce3+ showed three exponential decay time components under γ-ray excitation. From the measured scintillation properties, we consider this material is a promising scintillator for radiation detection.

  11. Luminescence and scintillation properties of Tl- and In-doped CsCl crystals

    NASA Astrophysics Data System (ADS)

    Sakai, Takumi; Koshimizu, Masanori; Fujimoto, Yutaka; Nakauchi, Daisuke; Yanagida, Takayuki; Asai, Keisuke

    2017-06-01

    Optical and scintillation properties of CsCl:Tl and CsCl:In single crystals were investigated. Ions Tl+ and In+ were selected as dopants to enhance the light yield of CsCl crystals. Luminescence and scintillation spectra of CsCl:Tl and CsCl:In could be attributed to the relaxed excited state (RES) originating from each dopant ion. The decay-time constants of the fast component had values of 5.4 ns for CsCl:Tl and 2.2 ns for CsCl:In, and can be ascribed to the overlapping of on-center STE and auger-free luminescence (AFL) for CsCl:Tl and only AFL for CsCl:In, respectively. Decay-time constants of the slow component were relatively long (220 ns for CsCl:Tl and 240 ns for CsCl:In), possibly owing to their low energy transfer rate from host to each dopant ion. The light yields of CsCl:1%Tl and CsCl:0.5%Tl were estimated to be 2800 and 2200 photons/MeV, respectively. The light yield of CsCl:0.5%In crystals was estimated to be 2200 photons/MeV. In conclusion, the light yield of pure CsCl (several ten photons/MeV) can be enhanced by doping Tl+ and In+ while maintaining the fast component of the CsCl crystal.

  12. Comparative Studies of Optical and Scintillation Properties between LiGaO2 and LiAlO2 Crystals

    NASA Astrophysics Data System (ADS)

    Yanagida, Takayuki; Fujimoto, Yutaka; Koshimizu, Masanori; Kawano, Naoki; Okada, Go; Kawaguchi, Noriaki

    2017-09-01

    We have investigated optical and scintillation properties of LiGaO2 and LiAlO2 crystals. From the transmittance spectra, the absorption edges were found to be around 200 nm but wider band gap was confirmed for LiAlO2 than LiGaO2. Both photoluminescence and scintillation spectra showed a broad emission band peaking at 340 nm in the both crystals. The scintillation decay times of LiGaO2 were 460 ns and 2.8 µs while that of LiAlO2 was 2 µs. Under neutron irradiation from 252Cf, the absolute scintillation light yields of LiGaO2 and LiAlO2 were 3300 ± 300 and 7200 ± 700 ph/n, respectively.

  13. Recent results and perspectives of ββ decay experiments with crystal scintillators at Gran Sasso

    SciTech Connect

    Bernabei, R.

    2013-12-30

    Crystal scintillators offer important tools to investigate ββ decay modes in various isotopes with a well known technology and the possibility of enrichment of the material in specific isotopes. Large efforts to develop and use highly radiopure dedicated detectors are carried out at Gran Sasso by the DAMA-Kiev collaboration. These efforts have allowed the investigation of many types of decay modes in several isotopes and the improvement of the existing limits or the set of new ones. A short summary on main aspects is given in this paper.

  14. Readout of undoped CsI and CeF{sub 3} crystals using scintillating fibers and bars

    SciTech Connect

    Woody, C.L.; Stoll, S.P.; Frank, J.S.

    1995-08-01

    An investigation has been made of a readout technique for undoped cesium iodide and cerium fluoride crystals using scintillating fibers and bars. The method uses the fluors in the scintillator as wavelength shifters to absorb the primary UV scintillation light from the crystals and reemit it at a longer wavelength which can be more easily propagated over large distances. A study was made for various types of fibers (BCF-10, BCF-12 and BCF-20), giving the dependence of the light output on fluor type, fiber diameter and the spacing between fibers. Similar studies are made for several types of bars (BC-404 and BC-408) which compare the light output for various bar thicknesses, flour concentrations and geometrical configurations. An initial investigation also showed that this technique can be used to read out CeF{sub 3} crystals.

  15. Scintillation properties of Eu-doped CsCl and CsBr crystals

    NASA Astrophysics Data System (ADS)

    Saeki, Keiichiro; Koshimizu, Masanori; Fujimoto, Yutaka; Yanagida, Takayuki; Okada, Go; Yahaba, Takuma; Tanaka, Hironori; Asai, Keisuke

    2016-11-01

    Eu-doped CsCl and CsBr crystals were grown by the vertical Bridgman-Stockbarger method and the scintillation properties of the crystals were investigated. The radioluminescence (RL) bands of CsCl:Eu were observed at 245-270 nm and 450 nm. The former bands are attributed to Auger-free luminescence, and the latter band is attributed to Eu2+ 5d-4f transitions. CsBr:Eu showed an RL band at 435 nm, and this broad band is attributed to Eu2+ 5d-4f transitions. The scintillation decay-time constants of the slow components for CsCl:Eu and CsBr:Eu were 0.38 and 2.8 μs, respectively. Based on the pulse-height spectra for 662 keV gamma ray from 137Cs, the light yield of CsCl:Eu and CsBr:Eu are estimated to be 1700 and 2500 photons/MeV, respectively.

  16. Pulse-shape discrimination with Cs2HfCl6 crystal scintillator

    NASA Astrophysics Data System (ADS)

    Cardenas, C.; Burger, A.; Goodwin, B.; Groza, M.; Laubenstein, M.; Nagorny, S.; Rowe, E.

    2017-10-01

    The results of investigation into cesium hafnium chloride (Cs2HfCl6) scintillating crystals as a promising detector to search for rare nuclear processes occurring in Hf isotopes is reported. The light output, quenching factor, and pulse-shape characteristics have been investigated at room temperature. The scintillation response of the crystal induced by α-particles and γ-quanta were studied to determine possibility of particle discrimination. Using the optimal filter method we obtained clear separation between signals with a factor of merit (FOM) = 9.3. This indicates that we are able to fully separate signals originating from α-particles and γ-quanta. Similar fruitful discrimination power was obtained by applying the mean time method (FOM = 7) and charge integration method (FOM = 7.5). The quenching factor for collimated 4 MeV α-particles is found to be 0.36, showing that α-particles generate more than a third of the light compared to γ-quanta at the same energy.

  17. High speed growth of SrI2 scintillator crystals by the EFG process

    NASA Astrophysics Data System (ADS)

    Calvert, G.; Guguschev, C.; Burger, A.; Groza, M.; Derby, J. J.; Feigelson, R. S.

    2016-12-01

    Strontium iodide (SrI2), an important new scintillator crystal having a high light yield and excellent energy resolution, was grown for the first time by the edge-defined film-fed (EFG) growth method. Using high purity starting materials and floating dies made of graphite, fused quartz or AlN, large cylindrical, planar or square cross-section single crystals (12-15 mm across and >7 cm long) were produced at growth rates up to 15 mm/h, significantly faster than the current Bridgman growth technology. Details on the equipment used to grow this deliquescent material and on its growth behavior are given along with some discussion of crystalline quality.

  18. Precision machining and polishing of scintillating crystals for large calorimeters and hodoscopes

    NASA Astrophysics Data System (ADS)

    Wuest, C. R.; Fuchs, B. A.; Holdener, F. R.; Heck, J. L., Jr.

    1994-04-01

    New machining and polishing techniques have been developed for large scintillating crystal arrays such as the Barium Fluoride Electromagnetic Calorimeter for the GEM Detector at SSCL, the Crystal Clear Collaboration's cerium fluoride or lead tungstenate calorimeter at the proposed LHC and CERN, the PHENIX Detector at RHIC (barium fluoride), and the cesium iodide Calorimeter for the BaBar Detector at PEP-2 B Factory at SLAC. The machining and polishing methods to be presented in this paper provide crystalline surfaces without sub-surface damage or deformation as verified by Rutherford Back-scattering (RBS) analysis. Surface roughness of about 10-20 A and sub-micron mechanical tolerances have been demonstrated on large barium fluoride crystal samples. Mass production techniques have also been developed for machining the proper angled surfaces and polishing up to five 50 cm long crystals at one time. These techniques utilize kinematic mount technology developed at LLNL to allow precision machining and polishing of complex surfaces. They will present this technology along with detailed surface studies of barium fluoride and cerium fluoride crystals polished with this technique.

  19. Precision machining and polishing of scintillating crystals for large calorimeters and hodoscopes. Revision 1

    SciTech Connect

    Wuest, C.R.; Fuchs, B.A.; Holdener, F.R.; Heck, J.L. Jr.

    1994-04-01

    New machining and polishing techniques have been developed for large scintillating crystal arrays such as the Barium Fluoride Electromagnetic Calorimeter for the GEM Detector at SSCL, the Crystal Clear Collaboration`s cerium fluoride or lead tungstenate calorimeter at the proposed LHC and CERN, the PHENIX Detector at RHIC (barium fluoride), and the cesium iodide Calorimeter for the BaBar Detector at PEP-2 B Factory at SLAC. The machining and polishing methods to be presented in this paper provide crystalline surfaces without sub-surface damage or deformation as verified by Rutherford Back-scattering (RBS) analysis. Surface roughness of about 10--20 angstroms and sub-micron mechanical tolerances have been demonstrated on large barium fluoride crystal samples. Mass production techniques have also been developed for machining the proper angled surfaces and polishing up to five 50 cm long crystals at one time. These techniques utilize kinematic mount technology developed at LLNL to allow precision machining and polishing of complex surfaces. They will present this technology along with detailed surface studies of barium fluoride and cerium fluoride crystals polished with this technique.

  20. Effects of Na co-doping on optical and scintillation properties of Eu:LiCaAlF6 scintillator single crystals

    NASA Astrophysics Data System (ADS)

    Tanaka, Chieko; Yokota, Yuui; Kurosawa, Shunsuke; Yamaji, Akihiro; Ohashi, Yuji; Kamada, Kei; Nikl, Martin; Yoshikawa, Akira

    2017-06-01

    Na co-doped Eu: LiCaAlF6 (Eu, Na: LiCAF) single crystals were grown by the micro-pulling-down (μ-PD) method, and their optical and scintillation properties were examined to reveal the effects of the Na co-doping. The crystals were single-phase materials demonstrating structure isomorphic with that of undoped LiCAF. To perform the crystals characterization, the specimens with dimensions of several millimeters were cut from highly transparent and crack free fragments of the crystals and polished. It was observed that Na co-doping resulted modification of the transmittance and the excitation spectra, and increased the light yield detected under neutron irradiation.

  1. Effects of melt aging and off-stoichiometric melts on CsSrI3:Eu(2+) single crystal scintillators.

    PubMed

    Wu, Yuntao; Zhuravleva, Mariya; Johnson, Jesse Ashby; Wei, Hua; Koschan, Merry; Melcher, Charles L

    2016-03-28

    Ternary halide scintillators are commonly prepared from a mixture of commercially available binary halides. The initial binary halides may contain excess halogen ions or have different volatilities, which could lead to loss of stoichiometry of the resulting ternary halide crystals and potentially negatively affect optical and scintillation properties. In this work, the effects of vacuum aging of the melt (melt aging) and use of off-stoichiometric melts via introduction of excess CsI on the crystal quality and scintillation properties of CsSrI3:Eu(2+), a promising scintillator for gamma-ray detection applications, are investigated. The phase purity of the grown samples was confirmed by powder X-ray diffraction and differential scanning calorimeter measurements, and the existence of matrix composition variations is revealed by energy-dispersive X-ray spectroscopy analyses. An abnormal relationship between the full energy peak and the shaping time, i.e. full energy peak broadening or existence of two full energy peaks, in the melt-aged and off-stoichiometric samples is observed. It is ascribed to a slow scintillation decay event in a time scale between 15 and 50 μs. For the CsSrI3:Eu(2+) single crystal grown from a stoichiometric melt without melt aging treatment, an energy resolution of 5.0% at 662 keV and a light yield of 48,000 ± 2000 photons per MeV can be achieved at a size of 1.4 cm(3).

  2. Research activity with different types of scintillation materials

    NASA Astrophysics Data System (ADS)

    Brinkmann, K.-T.; Borisevich, A.; Diehl, S.; Dormenev, V.; Houzvicka, J.; Korjik, M.; Novotny, R. W.; Zaunick, H.-G.; Zimmermann, S.

    2016-10-01

    Nowadays there is a growing interest and demand in the development of new types of scintillation materials for experimental high energy physics. Future detector developments will focus on cheap, fast, and radiation hard materials, especially for application in collider experiments. The most recent results obtained by the Giessen group in close cooperation with colleagues from different institutes will be presented. The new start of the mass production of high quality lead tungstate crystals (PbWO4, PWO) for electromagnetic calorimetry was started by the company CRYTUR (Turnov, Czech Republic). We will present a detailed progress report on the research program of lead tungstate performed in the last two years. The latest results in the development of LuAG:Ce, YAG:Ce and LYSO:Ce inorganic fibers, grown by the micro pulling down method and cut with the heated wire technique as well as new glass ceramics material BaO*2SiO2 (DSB) doped by Ce and Gd will be presented. In addition, different samples of the organic plastic scintillator EJ-260 produced by the company Eljen Technology (Sweetwater, USA) have been characterized. 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 gamma-source accumulating an integral dose of 100 Gy.

  3. Optical transmission damage of undoped and Ce doped Y3Al5O12 scintillation crystals under 24 GeV protons high fluence

    NASA Astrophysics Data System (ADS)

    Auffray, E.; Fedorov, A.; Dormenev, V.; Houžvička, J.; Korjik, M.; Lucchini, M. T.; Mechinsky, V.; Ochesanu, S.

    2017-06-01

    This report presents results on the optical transmission damage of undoped and Ce doped Y3Al5O12 scintillation crystals under high fluence of 24 GeV protons. We observed that, similarly to other middle heavy scintillators, it possesses the unique radiation hardness at fluence values as high as 5×1014 p/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.

  4. Simulation of light transport in scintillators based on 3D characterization of crystal surfaces

    PubMed Central

    Cherry, Simon R.

    2013-01-01

    In the development of positron emission tomography (PET) detectors, understanding and optimizing scintillator light collection is critical for achieving high performance, particularly when the design incorporates depth-of-interaction (DOI) encoding or time-of-flight information. Monte-Carlo simulations play an important role in guiding research in detector designs and popular software such as GATE now include models of light transport in scintillators. Although current simulation toolkits are able to provide accurate models of perfectly polished surfaces, they do not successfully predict light output for other surface finishes, for example those often used in DOI-encoding detectors. The lack of accuracy of those models mainly originates from a simplified description of rough surfaces as an ensemble of micro-facets determined by the distribution of their normal, typically a Gaussian distribution. The user can specify the standard deviation of this distribution, but this parameter does not provide a full description of the surface reflectance properties. We propose a different approach based on 3D measurements of the surface using atomic force microscopy (AFM). Polished and rough (unpolished) crystals were scanned to compute the surface reflectance properties. The angular distributions of reflectance and reflected rays were computed and stored in look-up tables (LUTs). The LUTs account for the effect of incidence angle and were integrated in a light transport model. Crystals of different sizes were simulated with and without reflector. The simulated maximum light output and the light output as a function of DOI showed very good agreement with experimental characterization of the crystals, indicating that our approach provides an accurate model of polished and rough surfaces and could be used to predict light collection in scintillators. This model is based on a true 3D representation of the surface, makes no assumption about the surface and provides insight on the

  5. Simulation of light transport in scintillators based on 3D characterization of crystal surfaces.

    PubMed

    Roncali, Emilie; Cherry, Simon R

    2013-04-07

    In the development of positron emission tomography (PET) detectors, understanding and optimizing scintillator light collection is critical for achieving high performance, particularly when the design incorporates depth-of-interaction (DOI) encoding or time-of-flight information. Monte-Carlo simulations play an important role in guiding research in detector designs and popular software such as GATE now include models of light transport in scintillators. Although current simulation toolkits are able to provide accurate models of perfectly polished surfaces, they do not successfully predict light output for other surface finishes, for example those often used in DOI-encoding detectors. The lack of accuracy of those models mainly originates from a simplified description of rough surfaces as an ensemble of micro-facets determined by the distribution of their normal, typically a gaussian distribution. The user can specify the standard deviation of this distribution, but this parameter does not provide a full description of the surface reflectance properties. We propose a different approach based on 3D measurements of the surface using atomic force microscopy. Polished and rough (unpolished) crystals were scanned to compute the surface reflectance properties. The angular distributions of reflectance and reflected rays were computed and stored in look-up tables (LUTs). The LUTs account for the effect of incidence angle and were integrated in a light transport model. Crystals of different sizes were simulated with and without reflector. The simulated maximum light output and the light output as a function of DOI showed very good agreement with experimental characterization of the crystals, indicating that our approach provides an accurate model of polished and rough surfaces and could be used to predict light collection in scintillators. This model is based on a true 3D representation of the surface, makes no assumption about the surface and provides insight on the optical

  6. Simulation of light transport in scintillators based on 3D characterization of crystal surfaces

    NASA Astrophysics Data System (ADS)

    Roncali, Emilie; Cherry, Simon R.

    2013-04-01

    In the development of positron emission tomography (PET) detectors, understanding and optimizing scintillator light collection is critical for achieving high performance, particularly when the design incorporates depth-of-interaction (DOI) encoding or time-of-flight information. Monte-Carlo simulations play an important role in guiding research in detector designs and popular software such as GATE now include models of light transport in scintillators. Although current simulation toolkits are able to provide accurate models of perfectly polished surfaces, they do not successfully predict light output for other surface finishes, for example those often used in DOI-encoding detectors. The lack of accuracy of those models mainly originates from a simplified description of rough surfaces as an ensemble of micro-facets determined by the distribution of their normal, typically a Gaussian distribution. The user can specify the standard deviation of this distribution, but this parameter does not provide a full description of the surface reflectance properties. We propose a different approach based on 3D measurements of the surface using atomic force microscopy. Polished and rough (unpolished) crystals were scanned to compute the surface reflectance properties. The angular distributions of reflectance and reflected rays were computed and stored in look-up tables (LUTs). The LUTs account for the effect of incidence angle and were integrated in a light transport model. Crystals of different sizes were simulated with and without reflector. The simulated maximum light output and the light output as a function of DOI showed very good agreement with experimental characterization of the crystals, indicating that our approach provides an accurate model of polished and rough surfaces and could be used to predict light collection in scintillators. This model is based on a true 3D representation of the surface, makes no assumption about the surface and provides insight on the optical

  7. Luminescence and scintillation properties of Tl- and Ce-doped Cs2HfCl6 crystals

    NASA Astrophysics Data System (ADS)

    Saeki, Keiichiro; Fujimoto, Yutaka; Koshimizu, Masanori; Nakauchi, Daisuke; Tanaka, Hironori; Yanagida, Takayuki; Asai, Keisuke

    2017-02-01

    The luminescence and scintillation properties of Tl- and Ce-doped Cs2HfCl6 crystals were investigated by photoluminescence and radioluminescence spectroscopy. In the photoluminescence spectra, emission bands of the activators were observed at 500 nm for Tl-doped Cs2HfCl6, and at 340 and 380 nm for Ce-doped Cs2HfCl6. The radioluminescence bands were observed at 405 and 430 nm for Tl- and Ce-doped Cs2HfCl6, respectively. Scintillation decay time constants for the Tl- and Ce-doped Cs2HfCl6 were smaller than those for the corresponding undoped crystals. Scintillation light yields for Tl- and Ce-doped Cs2HfCl6 were estimated to be 23,700 and 15,700 photons/MeV, respectively.

  8. In situ diagnostics of the crystal-growth process through neutron imaging: application to scintillators.

    PubMed

    Tremsin, Anton S; Makowska, Małgorzata G; Perrodin, Didier; Shalapska, Tetiana; Khodyuk, Ivan V; Trtik, Pavel; Boillat, Pierre; Vogel, Sven C; Losko, Adrian S; Strobl, Markus; Kuhn, L Theil; Bizarri, Gregory A; Bourret-Courchesne, Edith D

    2016-06-01

    Neutrons are known to be unique probes in situations where other types of radiation fail to penetrate samples and their surrounding structures. In this paper it is demonstrated how thermal and cold neutron radiography can provide time-resolved imaging of materials while they are being processed (e.g. while growing single crystals). The processing equipment, in this case furnaces, and the scintillator materials are opaque to conventional X-ray interrogation techniques. The distribution of the europium activator within a BaBrCl:Eu scintillator (0.1 and 0.5% nominal doping concentrations per mole) is studied in situ during the melting and solidification processes with a temporal resolution of 5-7 s. The strong tendency of the Eu dopant to segregate during the solidification process is observed in repeated cycles, with Eu forming clusters on multiple length scales (only for clusters larger than ∼50 µm, as limited by the resolution of the present experiments). It is also demonstrated that the dopant concentration can be quantified even for very low concentration levels (∼0.1%) in 10 mm thick samples. The interface between the solid and liquid phases can also be imaged, provided there is a sufficient change in concentration of one of the elements with a sufficient neutron attenuation cross section. Tomographic imaging of the BaBrCl:0.1%Eu sample reveals a strong correlation between crystal fractures and Eu-deficient clusters. The results of these experiments demonstrate the unique capabilities of neutron imaging for in situ diagnostics and the optimization of crystal-growth procedures.

  9. In situ diagnostics of the crystal-growth process through neutron imaging: application to scintillators

    DOE PAGES

    Tremsin, Anton S.; Makowska, Małgorzata G.; Perrodin, Didier; ...

    2016-04-12

    Neutrons are known to be unique probes in situations where other types of radiation fail to penetrate samples and their surrounding structures. In this paper it is demonstrated how thermal and cold neutron radiography can provide time-resolved imaging of materials while they are being processed (e.g.while growing single crystals). The processing equipment, in this case furnaces, and the scintillator materials are opaque to conventional X-ray interrogation techniques. The distribution of the europium activator within a BaBrCl:Eu scintillator (0.1 and 0.5% nominal doping concentrations per mole) is studiedin situduring the melting and solidification processes with a temporal resolution of 5–7 s.more » The strong tendency of the Eu dopant to segregate during the solidification process is observed in repeated cycles, with Eu forming clusters on multiple length scales (only for clusters larger than ~50 µm, as limited by the resolution of the present experiments). It is also demonstrated that the dopant concentration can be quantified even for very low concentration levels (~0.1%) in 10 mm thick samples. The interface between the solid and liquid phases can also be imaged, provided there is a sufficient change in concentration of one of the elements with a sufficient neutron attenuation cross section. Tomographic imaging of the BaBrCl:0.1%Eu sample reveals a strong correlation between crystal fractures and Eu-deficient clusters. The results of these experiments demonstrate the unique capabilities of neutron imaging forin situdiagnostics and the optimization of crystal-growth procedures.« less

  10. In situ diagnostics of the crystal-growth process through neutron imaging: application to scintillators

    PubMed Central

    Tremsin, Anton S.; Makowska, Małgorzata G.; Perrodin, Didier; Shalapska, Tetiana; Khodyuk, Ivan V.; Trtik, Pavel; Boillat, Pierre; Vogel, Sven C.; Losko, Adrian S.; Strobl, Markus; Kuhn, L. Theil; Bizarri, Gregory A.; Bourret-Courchesne, Edith D.

    2016-01-01

    Neutrons are known to be unique probes in situations where other types of radiation fail to penetrate samples and their surrounding structures. In this paper it is demonstrated how thermal and cold neutron radiography can provide time-resolved imaging of materials while they are being processed (e.g. while growing single crystals). The processing equipment, in this case furnaces, and the scintillator materials are opaque to conventional X-ray interrogation techniques. The distribution of the europium activator within a BaBrCl:Eu scintillator (0.1 and 0.5% nominal doping concentrations per mole) is studied in situ during the melting and solidification processes with a temporal resolution of 5–7 s. The strong tendency of the Eu dopant to segregate during the solidification process is observed in repeated cycles, with Eu forming clusters on multiple length scales (only for clusters larger than ∼50 µm, as limited by the resolution of the present experiments). It is also demonstrated that the dopant concentration can be quantified even for very low concentration levels (∼0.1%) in 10 mm thick samples. The interface between the solid and liquid phases can also be imaged, provided there is a sufficient change in concentration of one of the elements with a sufficient neutron attenuation cross section. Tomographic imaging of the BaBrCl:0.1%Eu sample reveals a strong correlation between crystal fractures and Eu-deficient clusters. The results of these experiments demonstrate the unique capabilities of neutron imaging for in situ diagnostics and the optimization of crystal-growth procedures. PMID:27275133

  11. Exploring growth conditions and Eu2+ concentration effects for KSr2I5:Eu scintillator crystals

    NASA Astrophysics Data System (ADS)

    Stand, L.; Zhuravleva, M.; Camarda, G.; Lindsey, A.; Johnson, J.; Hobbs, C.; Melcher, C. L.

    2016-04-01

    Our current research is focused on understanding dopant optimization, growth rate, homogeneity and their impact on the overall performance of KSr2I5:Eu2+ single crystal scintillators. In this work we have investigated the effects of Eu2+ concentration in the potassium strontium iodide matrix, and we found that the concentration needed to maximize the light yield was 4 mol%. In order to assess the effects of the pulling rate, we grew single crystals at 12, 24 and 120 mm/day via the vertical Bridgman technique. For the sample sizes measured (5×5×5 mm3), we found that the crystal grown at the fastest rate of 120 mm/day showed a light yield within ~7% of the more slowly grown boules, and no significant change was observed in the energy resolution. Therefore, light yields from 88,000 to 96,000 ph/MeV and energy resolutions from 2.4 to 3.0% (at 662 keV) were measured for KSr2I5:Eu 4% over a relatively wide range of growth conditions. In order to assess the homogeneity of KSr2I5:Eu 4%, a newly developed micro-resolution X-ray technique was used to map the light yield as a function of excitation position. In the crystals that we studied, we did not observe any significant inhomogeneity other than a smooth gradient due to light collection and self absorption effects.

  12. Recent progress in oxide scintillation crystals development by low-thermal gradient Czochralski technique for particle physics experiments

    NASA Astrophysics Data System (ADS)

    Shlegel, V. N.; Borovlev, Yu. A.; Grigoriev, D. N.; Grigorieva, V. D.; Danevich, F. A.; Ivannikova, N. V.; Postupaeva, A. G.; Vasiliev, Ya. V.

    2017-08-01

    Modern particle physics experiments call for high performance scintillation detectors with unique properties: radiation-resistant in high energy and astrophysics, highly radiopure, containing certain elements or enriched isotopes in astroparticle physics. The low-thermal gradient Czochralski (LTG CZ) crystal growth technique provides excellent quality large volume radiopure crystal scintillators. Absence of thermoelastic stress in the crystal and overheating of the melt in the LTG CZ method is particularly significant in production of crystalline materials with strong thermal anisotropic properties and low mechanical strength, with a very high yield of crystalline boules and low losses of initial charge, crucially important in production of crystal scintillators from enriched isotopes for double beta decay experiments. Here we discuss progress in development of the well known scintillators (Bi4Ge3O12 (BGO), CdWO4, ZnWO4, CaMoO4, PbMoO4), as well as R&D of new materials (ZnMoO4, Li2MoO4, Na2Mo2O7) for the next generation experiments in particle physics.

  13. SiPM optical crosstalk amplification due to scintillator crystal: effects on timing performance.

    PubMed

    Gola, Alberto; Ferri, Alessandro; Tarolli, Alessandro; Zorzi, Nicola; Piemonte, Claudio

    2014-07-07

    For a given photon detection efficiency (PDE), the primary, Poisson distributed, dark count rate of the detector (DCR0) is one of the most limiting factors affecting the timing resolution of a silicon photomultiplier (SiPM) in the scintillation light readout. If the effects of DCR0 are removed through a suitable baseline compensation algorithm or by cooling, it is possible to clearly observe another phenomenon that limits the PDE, and thus the timing resolution of the detector. It is caused by the optical crosstalk of the SiPM, which is significantly increased by the presence of the scintillator. In this paper, we describe this phenomenon, which is also easily observed from the reverse I-V curve of the device, and we relate it to the measured coincidence resolving time in 511 keV γ-ray measurements. We discuss its consequences on the SiPM design and, in particular, we observe that there is an optimal cell size, dependent on both SiPM and crystal parameters, that maximizes the PDE in presence of optical crosstalk. Finally, we report on a crosstalk simulator developed to study the phenomenon and we compare the simulation results obtained for different SiPM technologies, featuring different approaches to the reduction of the crosstalk.

  14. Defect Engineering in SrI2:Eu2+ Single Crystal Scintillators

    SciTech Connect

    Wu, Yuntao; Boatner, Lynn A.; Lindsey, Adam C.; Zhuravleva, Mariya; Jones, Steven; Auxier, John D.; Hall, Howard L.; Melcher, Charles L.

    2015-06-23

    Eu2+-activated strontium iodide is an excellent single crystal scintillator used for gamma-ray detection and significant effort is currently focused on the development of large-scale crystal growth techniques. A new approach of molten-salt pumping or so-called melt aging was recently applied to optimize the crystal quality and scintillation performance. Nevertheless, a detailed understanding of the underlying mechanism of this technique is still lacking. The main purpose of this paper is to conduct an in-depth study of the interplay between microstructure, trap centers and scintillation efficiency after melt aging treatment. Three SrI2:2 mol% Eu2+ single crystals with 16 mm diameter were grown using the Bridgman method under identical growth conditions with the exception of the melt aging time (e.g. 0, 24 and 72 hours). Using energy-dispersive X-ray spectroscopy, it is found that the matrix composition of the finished crystal after melt aging treatment approaches the stoichiometric composition. The mechanism responsible for the formation of secondary phase inclusions in melt-aged SrI2:Eu2+ is discussed. Simultaneous improvement in light yield, energy resolution, scintillation decay-time and afterglow is achieved in melt-aged SrI2:Eu2+. The correlation between performance improvement and defect structure is addressed. The results of this paper lead to a better understanding of the effects of defect engineering in control and optimization of metal halide scintillators using the melt aging technique.

  15. New Tl2LaBr5: Ce3+ crystal scintillator for γ-rays detection

    NASA Astrophysics Data System (ADS)

    Kim, H. J.; Rooh, Gul; Khan, Arshad; Kim, Sunghwan

    2017-03-01

    In this study we present our preliminary report on the scintillation properties of new Ce-doped Tl2LaBr5 single crystal. Two zones vertical Bridgman technique is used for the growth of this compound. Pure and Ce-doped samples showed maximum emission peaks at 435 nm and 415 nm, respectively. Best light yield of 43,000±4300 ph/MeV with 6.3% (FWHM) energy resolution is obtained for 5% Ce-doped sample under γ-ray excitation. Single exponential decay time constant of 25 ns is observed for 5% Ce doped sample. Effective Z-number is found to be 67, therefore efficient detection of X- and γ-ray will be possible. Preliminary results revealed that this compound will be an ideal candidate for the medical imaging techniques. Further investigations are under way for the determination of optimized conditions of this compound.

  16. Scintillation characterizations of Tl 2 LiLuCl 6 : Ce 3+ single crystal

    NASA Astrophysics Data System (ADS)

    Rooh, Gul; Kim, H. J.; Jang, Jonghun; Kim, Sunghwan

    2017-07-01

    0.5%, 1%, 3% and 5% Ce-concentration single crystals of Tl2LiLuCl6 were grown from the melt using two zone vertical Bridgman technique. X-ray induced emission spectra showed Ce3+ emission between 370 nm and 540 nm wavelength range. Energy resolution, light yield and decay time of the grown samples were measured under {\\gamma}-ray excitation at room temperature. Energy resolution of 5.6% (FWHM) with 27,000+-2700 light yield is found for 1%Ce doped sample. For the same dopant concentration, three decay time components are also observed. Variation of scintillation properties is observed as a function of dopant concentration in this material.This material will provide excellent detection efficiency for X- and {\\gamma}-rays due to its high effective Z-number and density. It is expected that this scintillor will be a potential detector for the medical imaging techniques.

  17. Enhancement of directional broadband luminescence from a scintillation film via guided-mode resonance in a photonic crystal structure

    NASA Astrophysics Data System (ADS)

    Zhu, Zhichao; Liu, Bo; Cheng, Chuanwei; Zhang, Haifeng; Chen, Hong; Gu, Mu; Liu, Jinliang; Chen, Liang; Ouyang, Xiaoping; Xue, Chaofan; Wu, Yanqing

    2017-01-01

    Scintillation films play an important role in radiation detection. Improved light output and control of emission directionality are critical for practical applications. To obtain enhancement of broadband directional luminescence from a Lu2SiO5:Ce3+ scintillation film, a special photonic crystal structure is deposited on the film surface to provide multiple guided-mode resonances. The structure can be designed according to the application requirements. Numerical simulations are performed to analyze the enhancement. Overall, this method could be used when directional emission is required for radiation detection.

  18. Compact gamma-ray detection system for space applications based on photodiodes and CsI(TI) scintillation crystals

    NASA Astrophysics Data System (ADS)

    Graue, Roland; Stuffler, Timo; Goebel, Thomas

    1996-10-01

    For the measurement of astronomical gamma ray radiation in the energy range 50 keV to several MeV usually photomultiplier tubes (PMT) with scintillation crystals are used. However, due to the internal detection mechanism high voltage and single photon counting are required leading to heavy and structurally unpractical systems. Even APD's (avalanche photodiodes) do not circumvent the problem of the high voltage. Recent improvements in the performance of semiconductor detectors allow the use of large area and low noise pin photodiodes as innovative scintillation detectors with 40 - 100 V operating voltage only. Tl-doped CsI as scintillation crystal with a superior light yield has not only a much higher photon output compared to the light yield of pure CsI and BGO crystals which are used for the gamma ray detection with PMTs, but has also a perfect matching of spectral properties of the photodiode. This paper presents a comprehensive comparison with conventional PMT scintillation detector systems and the development activities of full size breadboards with such a photodiode/CsI(Tl) detector set-up. The relevant functional performance test results have shown the high technical maturity of this detector system and the principal feasibility for the application either in the INTEGRAL spectrometer and imager anticoincidence shield (ACS) or in image central detector system. The dedicated ACS configuration design featuring optimized mass budget combined with high gamma ray stopping efficiency is figured.

  19. Enhanced light extraction of scintillator using large-area photonic crystal structures fabricated by soft-X-ray interference lithography

    SciTech Connect

    Zhu, Zhichao; Wu, Shuang; Liu, Bo Cheng, Chuanwei; Gu, Mu; Chen, Hong; Xue, Chaofan; Zhao, Jun; Wang, Liansheng; Wu, Yanqing; Tai, Renzhong

    2015-06-15

    Soft-X-ray interference lithography is utilized in combination with atomic layer deposition to prepare photonic crystal structures on the surface of Bi{sub 4}Ge{sub 3}O{sub 12} (BGO) scintillator in order to extract the light otherwise trapped in the internal of scintillator due to total internal reflection. An enhancement with wavelength- and emergence angle-integration by 95.1% has been achieved. This method is advantageous to fabricate photonic crystal structures with large-area and high-index-contrast which enable a high-efficient coupling of evanescent field and the photonic crystal structures. Generally, the method demonstrated in this work is also suitable for many other light emitting devices where a large-area is required in the practical applications.

  20. Comparative analysis of the scintillation and thermoluminescent properties of Ce-doped LSO and YSO crystals and films

    NASA Astrophysics Data System (ADS)

    Zorenko, Yu.; Gorbenko, V.; Bilski, P.; Twardak, A.; Mandowska, E.; Mandowski, A.; Sidletskiy, O.

    2014-08-01

    The work is devoted to the comparative analysis of the scintillation and thermoluminescent properties of the undoped and Ce-doped A2SiO5 (A = Lu, Y) orthosilicates, prepared in single crystal form by the Czochralski method and in the form of single crystalline film using the liquid phase epitaxy method. We have found that differences in the methods of material preparation resulted in the significant differences in the scintillation and thermoluminescent properties of undoped and Ce doped YSO and LSO crystals and films. Such differences are caused by the presence or absence of main host defects (first of all, oxygen vacancies and flux related impurities) as emission and trapping centers in YSO and LSO crystals and films.

  1. R&D of crystal scintillators from enriched isotopes for high sensitivity double β decay experiments

    NASA Astrophysics Data System (ADS)

    Danevich, F. A.

    2013-12-01

    Experiments to search for neutrinoless double beta decay enters to a new phase when a sensitivity on the level of T1/2˜1026-1028 yr is required. Scintillating low temperature detectors possess important properties required for high-sensitivity double beta decay experiments: presence of elements of interest, high energy resolution and detection efficiency, low level of background thanks to excellent particle discrimination ability. High concentration of isotope of interest and as low as possible radioactive contamination are important requirements to crystal scintillators. Other crucial issues are maximal output of detectors and minimal loss of enriched materials. Prospects of several scintillation materials, enriched in isotopes promising for double beta decay experiments, are discussed.

  2. Characterization of Pr:LuAG scintillating crystals for X-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Bertoni, R.; Bonesini, M.; Cervi, T.; Clemenza, M.; De Bari, A.; Falcone, A.; Mazza, R.; Menegolli, A.; Nastasi, M.; Rossella, M.

    2016-07-01

    The main features of the Pr doped Lu3Al5O12 (Pr:LuAG) scintillating crystals for X-ray spectroscopy applications have been studied using different radioactive sources and photo-detectors. Pr:LuAG is cheaper, compared to a Germanium detector, but with remarkable properties which make it useful for many applications, from fundamental physics measurements to the PET imaging for medical purposes: high density, elevate light yield, fast response, high energy resolution, no hygroscopicity. A sample of Pr:LuAG crystals with 14 mm×14 mm surface area and 13 mm thickness and a NaI crystal of the same surface and 26 mm thickness used as a reference have been characterized with several radioactive sources, emitting photons in the range 100-1000keV. Different light detectors were adopted for the Pr:LuAG studies, sensitive to its UV emission (peak at 310 nm): a 3 in. PMT (Hamamatsu R11065) and new arrays of Hamamatsu SiPM S13361, with siliconic resin as a window. Preliminary results are presented on the performance of the Pr:LuAG crystals, to be mounted in a 2 × 2 array to be tested in the 2015 run of the FAMU experiment at RIKEN-RAL muon facility. The goal is the detection of the X-rays (around 130 keV) emitted during the de-excitation processes of the muonic hydrogen after the excitation with an IR laser with wavelength set at the resonance of the hyperfine splitting, to measure the muonic atom proton radius with unprecedented precision.

  3. Crystal growth and characterization of rare earth iodides for scintillation detection

    NASA Astrophysics Data System (ADS)

    van Loef, E. V.; Higgins, W. M.; Glodo, J.; Churilov, A. V.; Shah, K. S.

    2008-04-01

    In this paper we report on the crystal growth and characterization of a new class of inorganic scintillators based on the rare earth iodides, in particular LuI 3, YI 3 and GdI 3, doped with trivalent cerium. Single crystals of LuI 3:Ce 3+, YI 3:Ce 3+ and GdI 3:Ce 3+ were grown by the vertical Bridgman technique in evacuated silica ampoules. In some cases, tantalum or graphite crucibles were used to minimize wetting of the ampoule. X-ray excited optical luminescence spectra of LuI 3:Ce 3+, YI 3:Ce 3+ and GdI 3:Ce 3+ exhibit a broad band due to Ce 3+ emission, peaking in the 500-550 nm region. LuI 3:Ce 3+, YI 3:Ce 3+ and GdI 3:Ce 3+ show high light yields up to 100,000 photons/MeV and fast principle decay time constants of <40 ns. Energy resolutions measured at 662 keV are of the order of 3.5-9% (FWHM).

  4. Crystal growth and characterization of europium doped lithium strontium iodide scintillator as an ionizing radiation detector

    NASA Astrophysics Data System (ADS)

    Uba, Samuel

    High performance detectors used in the detection of ionizing radiation is critical to nuclear nonproliferation applications and other radiation detectors applications. In this research we grew and tested Europium doped Lithium Strontium Iodide compound. A mixture of lithium iodide, strontium iodide and europium iodide was used as the starting materials for this research. Congruent melting and freezing temperature of the synthesized compound was determined by differential scanning calorimetry (DSC) using a Setaram Labsys Evo DSC-DTA instrument. The melting temperatures were recorded at 390.35°C, 407.59°C and freezing temperature was recorded at 322.84°C from a graph of heat flow plotted against temperature. The synthesized material was used as the charge for the vertical Bridgeman growth, and a 6.5 cm and 7.7cm length boule were grown in a multi-zone transparent Mullen furnace. A scintillating detector of thickness 2.53mm was fabricated by mechanical lapping in mineral oil, and scintillating response and timing were obtained to a cesium source using CS-137 isotope. An energy resolution (FWHM over peak position) of 12.1% was observed for the 662keV full absorption peak. Optical absorption in the UV-Vis wavelength range was recorded for the grown crystal using a U-2900 UV/VIS Spectrophotometer. Absorption peaks were recorded at 194nm, 273nm, and 344nm from the absorbance spectrum, various optical parameters such as absorption coefficient, extinction coefficient, refractive index, and optical loss were derived. The optical band gap energy was calculated using Tauc relation expression at 1.79eV.

  5. Analytical Calculation of the Lower Bound on Timing Resolution for PET Scintillation Detectors Comprising High-Aspect-Ratio Crystal Elements

    PubMed Central

    Cates, Joshua W.; Vinke, Ruud; Levin, Craig S.

    2015-01-01

    Excellent timing resolution is required to enhance the signal-to-noise ratio (SNR) gain available from the incorporation of time-of-flight (ToF) information in image reconstruction for positron emission tomography (PET). As the detector’s timing resolution improves, so does SNR, reconstructed image quality, and accuracy. This directly impacts the challenging detection and quantification tasks in the clinic. The recognition of these benefits has spurred efforts within the molecular imaging community to determine to what extent the timing resolution of scintillation detectors can be improved and develop near-term solutions for advancing ToF-PET. Presented in this work, is a method for calculating the Cramér-Rao lower bound (CRLB) on timing resolution for scintillation detectors with long crystal elements, where the influence of the variation in optical path length of scintillation light on achievable timing resolution is non-negligible. The presented formalism incorporates an accurate, analytical probability density function (PDF) of optical transit time within the crystal to obtain a purely mathematical expression of the CRLB with high-aspect-ratio (HAR) scintillation detectors. This approach enables the statistical limit on timing resolution performance to be analytically expressed for clinically-relevant PET scintillation detectors without requiring Monte Carlo simulation-generated photon transport time distributions. The analytically calculated optical transport PDF was compared with detailed light transport simulations, and excellent agreement was found between the two. The coincidence timing resolution (CTR) between two 3×3×20 mm3 LYSO:Ce crystals coupled to analogue SiPMs was experimentally measured to be 162±1 ps FWHM, approaching the analytically calculated lower bound within 6.5%. PMID:26083559

  6. Analytical calculation of the lower bound on timing resolution for PET scintillation detectors comprising high-aspect-ratio crystal elements

    NASA Astrophysics Data System (ADS)

    Cates, Joshua W.; Vinke, Ruud; Levin, Craig S.

    2015-07-01

    Excellent timing resolution is required to enhance the signal-to-noise ratio (SNR) gain available from the incorporation of time-of-flight (ToF) information in image reconstruction for positron emission tomography (PET). As the detector’s timing resolution improves, so does SNR, reconstructed image quality, and accuracy. This directly impacts the challenging detection and quantification tasks in the clinic. The recognition of these benefits has spurred efforts within the molecular imaging community to determine to what extent the timing resolution of scintillation detectors can be improved and develop near-term solutions for advancing ToF-PET. Presented in this work, is a method for calculating the Cramér-Rao lower bound (CRLB) on timing resolution for scintillation detectors with long crystal elements, where the influence of the variation in optical path length of scintillation light on achievable timing resolution is non-negligible. The presented formalism incorporates an accurate, analytical probability density function (PDF) of optical transit time within the crystal to obtain a purely mathematical expression of the CRLB with high-aspect-ratio (HAR) scintillation detectors. This approach enables the statistical limit on timing resolution performance to be analytically expressed for clinically-relevant PET scintillation detectors without requiring Monte Carlo simulation-generated photon transport time distributions. The analytically calculated optical transport PDF was compared with detailed light transport simulations, and excellent agreement was found between the two. The coincidence timing resolution (CTR) between two 3× 3× 20 mm3 LYSO:Ce crystals coupled to analogue SiPMs was experimentally measured to be 162+/- 1 ps FWHM, approaching the analytically calculated lower bound within 6.5%.

  7. Optimizing light transport in scintillation crystals for time-of-flight PET: an experimental and optical Monte Carlo simulation study.

    PubMed

    Berg, Eric; Roncali, Emilie; Cherry, Simon R

    2015-06-01

    Achieving excellent timing resolution in gamma ray detectors is crucial in several applications such as medical imaging with time-of-flight positron emission tomography (TOF-PET). Although many factors impact the overall system timing resolution, the statistical nature of scintillation light, including photon production and transport in the crystal to the photodetector, is typically the limiting factor for modern scintillation detectors. In this study, we investigated the impact of surface treatment, in particular, roughening select areas of otherwise polished crystals, on light transport and timing resolution. A custom Monte Carlo photon tracking tool was used to gain insight into changes in light collection and timing resolution that were observed experimentally: select roughening configurations increased the light collection up to 25% and improved timing resolution by 15% compared to crystals with all polished surfaces. Simulations showed that partial surface roughening caused a greater number of photons to be reflected towards the photodetector and increased the initial rate of photoelectron production. This study provides a simple method to improve timing resolution and light collection in scintillator-based gamma ray detectors, a topic of high importance in the field of TOF-PET. Additionally, we demonstrated utility of our Monte Carlo simulation tool to accurately predict the effect of altering crystal surfaces on light collection and timing resolution.

  8. Optimizing light transport in scintillation crystals for time-of-flight PET: an experimental and optical Monte Carlo simulation study

    PubMed Central

    Berg, Eric; Roncali, Emilie; Cherry, Simon R.

    2015-01-01

    Achieving excellent timing resolution in gamma ray detectors is crucial in several applications such as medical imaging with time-of-flight positron emission tomography (TOF-PET). Although many factors impact the overall system timing resolution, the statistical nature of scintillation light, including photon production and transport in the crystal to the photodetector, is typically the limiting factor for modern scintillation detectors. In this study, we investigated the impact of surface treatment, in particular, roughening select areas of otherwise polished crystals, on light transport and timing resolution. A custom Monte Carlo photon tracking tool was used to gain insight into changes in light collection and timing resolution that were observed experimentally: select roughening configurations increased the light collection up to 25% and improved timing resolution by 15% compared to crystals with all polished surfaces. Simulations showed that partial surface roughening caused a greater number of photons to be reflected towards the photodetector and increased the initial rate of photoelectron production. This study provides a simple method to improve timing resolution and light collection in scintillator-based gamma ray detectors, a topic of high importance in the field of TOF-PET. Additionally, we demonstrated utility of our Monte Carlo simulation tool to accurately predict the effect of altering crystal surfaces on light collection and timing resolution. PMID:26114040

  9. Excellent pulse height uniformity response of a new LaBr3:Ce scintillation crystal for gamma ray imaging

    NASA Astrophysics Data System (ADS)

    Pani, R.; Cinti, M. N.; Fabbri, A.; Orlandi, C.; Pellegrini, R.; Scafè, R.; Colarieti-Tosti, M.

    2015-07-01

    Nuclear Medicine SPECT imaging is taking on new challenges, regarding the improvement of quality and contrast of images. In order to reach this goal, energy resolution and Compton rejection capability have to be enhanced. For detectors based on scintillation crystal, the choice of a scintillator with high light yield is suitable; recently one of the major candidates is Lanthanum Tri-Bromide (LaBr3:Ce), with its high 63,000 ph/MeV light yield. Unfortunately, LaBr3:Ce suffers size limitations due to the actual growth techniques (maximum 3 in. diameter) and has also elevated cost. For these reasons, great interest is shown on small field of view detectors based on LaBr3:Ce, thought for imaging of specific physiological process or organ. To improve energy resolution, continuous crystals are more appropriate instead than pixelated ones. Since in a continuous crystal a decrease in position linearity, due to the light reflections, is typically obtained at the edges, an absorbent treatment of surfaces is generally utilized for SPECT applications. On the other hand, light absorption causes a relevant degradation of local energy resolution and pulse height uniformity response, affecting local image contrast. In this work an analysis on a new continuous LaBr3:Ce scintillation crystal with size proper to a small field of view gamma imager but with reflective treatment of surfaces is presented. This leads up to outstanding overall and local energy resolution results and excellent pulse height uniformity response on the whole field of view. Furthermore, preliminary imaging results are satisfactory, compared to the ones from a scintillation crystal with absorbent edges.

  10. Monte Carlo and Lambertian light guide models of the light output from scintillation crystals at megavoltage energies

    SciTech Connect

    Evans, Philip M.; Mosleh-Shirazi, M. Amin; Harris, Emma J.; Seco, Joao

    2006-06-15

    A new model of the light output from single-crystal scintillators in megavoltage energy x-ray beams has been developed, based on the concept of a Lambertian light guide model (LLG). This was evaluated in comparison with a Monte Carlo (MC) model of optical photon transport, previously developed and reported in the literature, which was used as a gold standard. The LLG model was developed to enable optimization of scintillator detector design. In both models the dose deposition and light propagation were decoupled, the scintillators were cuboids, split into a series of cells as a function of depth, with Lambertian side and entrance faces, and a specular exit face. The signal in a sensor placed 1 and 1000 mm beyond the exit face was calculated. Cesium iodide (CSI) crystals of 1.5 and 3 mm square cross section and 1, 5, and 10 mm depth were modeled. Both models were also used to determine detector signal and optical gain factor as a function of CsI scintillator thickness, from 2 to 10 mm. Results showed a variation in light output with position of dose deposition of a factor of up to approximately 5, for long, thin scintillators (such as 10x1.5x1.5 mm{sup 3}). For short, fat scintillators (such as 1x3x3 mm{sup 3}) the light output was more uniform with depth. MC and LLG generally agreed to within 5%. Results for a sensor distance of 1 mm showed an increase in light output the closer the light originates to the exit face, while a distance of 1000 mm showed a decrease in light output the closer the light originates to the exit face. For a sensor distance of 1 mm, the ratio of signal for a 10 mm scintillator to that for a 2 mm scintillator was 1.98, whereas for the 1000 mm distance the ratio was 3.00. The ratio of quantum efficiency (QE) between 10 and 2 mm thicknesses was 4.62. We conclude that these models may be used for detector optimization, with the light guide model suitable for parametric study.

  11. Scintillator materials for calorimetry

    SciTech Connect

    Weber, M.J.

    1994-09-01

    Requirements for fast, dense scintillator materials for calorimetry in high energy physics and approaches to satisfying these requirements are reviewed with respect to possible hosts and luminescent species. Special attention is given to cerium-activated crystals, core-valence luminescence, and glass scintillators. The present state of the art, limitations, and suggestions for possible new scintillator materials are presented.

  12. Imaging characterization of a new gamma ray detector based on CRY019 scintillation crystal for PET and SPECT applications

    NASA Astrophysics Data System (ADS)

    Polito, C.; Pani, R.; Trigila, C.; Cinti, M. N.; Fabbri, A.; Frantellizzi, V.; De Vincentis, G.; Pellegrini, R.; Pani, R.

    2017-02-01

    In the last 40 years, in the field of Molecular Medicine imaging there has been a huge growth in the employment and in the improvement of detectors for PET and SPECT applications in order to reach accurate diagnosis of the diseases. The most important feature required to these detectors is an high quality of images that is usually obtained benefitting from the development of a wide number of new scintillation crystals with high imaging performances. In this contest, features like high detection efficiency, short decay time, great spectral match with photodetectors, absence of afterglow and low costs are surely attractive. However, there are other factors playing an important role in the realization of high quality images such as energy and spatial resolutions, position linearity and contrast resolution. With the aim to realize an high performace gamma ray detector for PET and SPECT applications, this work is focused on the evaluation of the imaging characteristics of a recently developed scintillation crystal, CRY019.

  13. Stimulated recovery of the optical transmission of PbWO 4 scintillation crystals for electromagnetic calorimeters after radiation damage

    NASA Astrophysics Data System (ADS)

    Dormenev, V.; Kuske, T.; Novotny, R. W.; Borisevich, A.; Fedorov, A.; Korjik, M.; Mechinski, V.; Missevitch, O.; Lugert, S.

    2010-11-01

    In this paper we describe the phenomenon of the stimulated recovery of radiation damage in lead tungstate scintillation crystals achieved via illumination by visible and infrared light. It allows fast and efficient in-situ recovery of the optical transmission either during beam-off periods or on-line during data accumulation. The application can substantially improve or extend the running period of the experiment by keeping the damage at a tolerable level.

  14. Growth and scintillation characterization of Ce3+-doped Rb2LiGdBr6 single crystals

    NASA Astrophysics Data System (ADS)

    Rooh, Gul; Kim, H. J.; Kim, Sunghwan; Khan, Sajid

    2016-10-01

    Growth and scintillation characterizations of the newly developed cerium doped Rb2LiGdBr6 (RLGB) single crystals were investigated. RLGB, which belongs to bromo-elpasolite crystal family, was grown by the vertical Bridgman technique with nominally 1%, 5%, and 10% Ce3+-concentration (mole%). X-ray excited luminescence spectra show typical Ce3+ bands between 350 to 460 nm wavelength regions. A good energy resolution of 5.5% (FWHM) and light yield of 25,500±2600 ph/MeV for 662 keV γ-rays were observed at 5% Ce3+-concentration. Under γ-ray excitation, RLGB:Ce3+ crystals display multi-exponential decays with Ce3+ like decay components at 23 ns and 29 ns for 1% and 5% Ce-concentrations, respectively. From the results, it is expected that this scintillator could be used as a thermal neutron detector because of Li and Gd ions in the host lattice. Also, like other inorganic halide scintillators, it is very hygroscopic.

  15. Growth of shape-controlled Ce:Y3Al5O12 scintillator crystal and their scintillation properties

    NASA Astrophysics Data System (ADS)

    Yokota, Yuui; Kurosawa, Shunsuke; Ohasi, Yuji; Kamada, Kei; Yoshikawa, Akira

    2016-10-01

    A shape-controlled Ce doped Y3Al5O12 (Ce:YAG) single crystal has been grown by a micro-pulling-down method using an Ir crucible with a square die. The as-grown Ce:YAG single crystal has square-shape and flat surfaces with high transparency. The shape-controlled Ce:YAG single crystal showed more than 70% transmittance from 530 nm to 900 nm without any cutting and polishing. An emission peak around 540 nm was observed in the radioluminescence spectrum under X-ray irradiation. In addition, the light yield and energy resolution under γ-ray irradiation of the as-grown crystal without any cutting and polishing were approximately 23,000 pH/MeV and 16%, respectively.

  16. Characterization of scintillator crystals for usage as prompt gamma monitors in particle therapy

    NASA Astrophysics Data System (ADS)

    Roemer, K.; Pausch, G.; Bemmerer, D.; Berthel, M.; Dreyer, A.; Golnik, C.; Hueso-González, F.; Kormoll, T.; Petzoldt, J.; Rohling, H.; Thirolf, P.; Wagner, A.; Wagner, L.; Weinberger, D.; Fiedler, F.

    2015-10-01

    Particle therapy in oncology is advantageous compared to classical radiotherapy due to its well-defined penetration depth. In the so-called Bragg peak, the highest dose is deposited; the tissue behind the cancerous area is not exposed. Different factors influence the range of the particle and thus the target area, e.g. organ motion, mispositioning of the patient or anatomical changes. In order to avoid over-exposure of healthy tissue and under-dosage of cancerous regions, the penetration depth of the particle has to be monitored, preferably already during the ongoing therapy session. The verification of the ion range can be performed using prompt gamma emissions, which are produced by interactions between projectile and tissue, and originate from the same location and time of the nuclear reaction. The prompt gamma emission profile and the clinically relevant penetration depth are correlated. Various imaging concepts based on the detection of prompt gamma rays are currently discussed: collimated systems with counting detectors, Compton cameras with (at least) two detector planes, or the prompt gamma timing method, utilizing the particle time-of-flight within the body. For each concept, the detection system must meet special requirements regarding energy, time, and spatial resolution. Nonetheless, the prerequisites remain the same: the gamma energy region (2 to 10 MeV), high counting rates and the stability in strong background radiation fields. The aim of this work is the comparison of different scintillation crystals regarding energy and time resolution for optimized prompt gamma detection.

  17. Metal-organic scintillator crystals for X-ray, gamma ray, and neutron detection

    DOEpatents

    Boatner, Lynn A [Oak Ridge, TN; Kolopus, James A [Clinton, TN; Neal, John S [Knoxville, TN; Ramey, Joanne Oxendine [Knoxville, TN; Wisniewski, Dariusz J [Torun, PL

    2012-01-03

    New metal-organic materials are useful as scintillators and have the chemical formula LX.sub.3(CH.sub.3OH).sub.4 where L is Y, Sc, or a lanthanide element, and X is a halogen element. An example of the scintillator materials is CeCl.sub.3(CH.sub.3OH).sub.4.

  18. Side readout of long scintillation crystal elements with digital SiPM for TOF-DOI PET

    PubMed Central

    Yeom, Jung Yeol; Vinke, Ruud; Levin, Craig S.

    2014-01-01

    Purpose: Side readout of scintillation light from crystal elements in positron emission tomography (PET) is an alternative to conventional end-readout configurations, with the benefit of being able to provide accurate depth-of-interaction (DOI) information and good energy resolution while achieving excellent timing resolution required for time-of-flight PET. This paper explores different readout geometries of scintillation crystal elements with the goal of achieving a detector that simultaneously achieves excellent timing resolution, energy resolution, spatial resolution, and photon sensitivity. Methods: The performance of discrete LYSO scintillation elements of different lengths read out from the end/side with digital silicon photomultipliers (dSiPMs) has been assessed. Results: Compared to 3 × 3 × 20 mm3 LYSO crystals read out from their ends with a coincidence resolving time (CRT) of 162 ± 6 ps FWHM and saturated energy spectra, a side-readout configuration achieved an excellent CRT of 144 ± 2 ps FWHM after correcting for timing skews within the dSiPM and an energy resolution of 11.8% ± 0.2% without requiring energy saturation correction. Using a maximum likelihood estimation method on individual dSiPM pixel response that corresponds to different 511 keV photon interaction positions, the DOI resolution of this 3 × 3 × 20 mm3 crystal side-readout configuration was computed to be 0.8 mm FWHM with negligible artifacts at the crystal ends. On the other hand, with smaller 3 × 3 × 5 mm3 LYSO crystals that can also be tiled/stacked to provide DOI information, a timing resolution of 134 ± 6 ps was attained but produced highly saturated energy spectra. Conclusions: The energy, timing, and DOI resolution information extracted from the side of long scintillation crystal elements coupled to dSiPM have been acquired for the first time. The authors conclude in this proof of concept study that such detector configuration has the potential to enable outstanding

  19. Side readout of long scintillation crystal elements with digital SiPM for TOF-DOI PET.

    PubMed

    Yeom, Jung Yeol; Vinke, Ruud; Levin, Craig S

    2014-12-01

    Side readout of scintillation light from crystal elements in positron emission tomography (PET) is an alternative to conventional end-readout configurations, with the benefit of being able to provide accurate depth-of-interaction (DOI) information and good energy resolution while achieving excellent timing resolution required for time-of-flight PET. This paper explores different readout geometries of scintillation crystal elements with the goal of achieving a detector that simultaneously achieves excellent timing resolution, energy resolution, spatial resolution, and photon sensitivity. The performance of discrete LYSO scintillation elements of different lengths read out from the end/side with digital silicon photomultipliers (dSiPMs) has been assessed. Compared to 3 × 3 × 20 mm(3) LYSO crystals read out from their ends with a coincidence resolving time (CRT) of 162 ± 6 ps FWHM and saturated energy spectra, a side-readout configuration achieved an excellent CRT of 144 ± 2 ps FWHM after correcting for timing skews within the dSiPM and an energy resolution of 11.8% ± 0.2% without requiring energy saturation correction. Using a maximum likelihood estimation method on individual dSiPM pixel response that corresponds to different 511 keV photon interaction positions, the DOI resolution of this 3 × 3 × 20 mm(3) crystal side-readout configuration was computed to be 0.8 mm FWHM with negligible artifacts at the crystal ends. On the other hand, with smaller 3 × 3 × 5 mm(3) LYSO crystals that can also be tiled/stacked to provide DOI information, a timing resolution of 134 ± 6 ps was attained but produced highly saturated energy spectra. The energy, timing, and DOI resolution information extracted from the side of long scintillation crystal elements coupled to dSiPM have been acquired for the first time. The authors conclude in this proof of concept study that such detector configuration has the potential to enable outstanding detector performance in terms of timing

  20. X-ray Luminescence Efficiency of GAGG:Ce Single Crystal Scintillators for use in Tomographic Medical Imaging Systems

    NASA Astrophysics Data System (ADS)

    David, S. L.; Valais, I. G.; Michail, C. M.; Kandarakis, I. S.

    2015-09-01

    The purpose of the present study was to evaluate different scintillator crystal samples, with a cross section of 3×3mm2 and various thicknesses ranging from 4mm up to 20mm, of the new mixed Gd3Al2Ga3O12:Ce (GAGG:Ce) scintillator material under X-ray irradiation, for potential applications in Tomographic Medical Imaging systems. Evaluation was performed by determining the X-ray luminescence efficiency (XLE) (emitted light energy flux over incident X-ray energy flux) in energies employed in general X-ray imaging. For the luminescence efficiency measurements, the scintillator samples were exposed to X-rays using a BMI General Medical Merate tube, with rotating Tungsten anode and inherent filtration equivalent to 2 mm Al. X-ray tube voltages between 50 to 130 kV were selected. An additional 20 mm filtration was introduced to the beam to simulate beam quality alternation equivalent to a human body. The emitted light energy flux measurements were performed using an experimental set up comprising a light integration sphere coupled to an EMI 9798B photomultiplier tube which was connected to a Cary 401 vibrating reed electrometer. The GAGG:Ce sample with dimensions 3×3×10 mm3 exhibited higher XLE values, in the whole X- ray energy range examined. XLE value equal to 0.013 was recorded for this crystal at 130 kVp - a setting frequently used in Computed Tomography applications.

  1. Luminescent and scintillation properties of Lu3Al5O12:Sc single crystal and single crystalline films

    NASA Astrophysics Data System (ADS)

    Zorenko, Y.; Gorbenko, V.; Voznyak, T.; Savchyn, V.; Nizhankovskiy, S.; Dan'ko, A.; Puzikov, V.; Laguta, V.; Mares, J. A.; Nikl, M.; Nejezchleb, K.; Batentschuk, M.; Winnacker, A.

    2012-10-01

    The work is dedicated to growth by the liquid phase epitaxy method and study of the luminescence and scintillation properties of Sc3+ doped single crystalline films (SCF) of Lu3Al5O12 (LuAG) garnet. The scintillation properties of SCF are compared with single crystal (SC) analogues grown by the Horizontal Direct Crystallization and Czochralski methods. We consider the dependence of intensity of the Sc3+ emission in LuAG host on the activator concentration and influence of flux contamination on the light yield (LY) of the Sc3+ luminescence in LuAG:Sc SCF with respect to their SC counterparts and the reference YAP:Ce scintillator. From the NMR investigations of LuAG:Sc SCF we confirm the substitution by Sc3+ ions both the octahedral and dodecahedral positions of LuAG host and formation of the ScAl and ScLu related emission centers, respectively. We also show that the luminescence spectrum in the UV range and decay kinetics of LuAG:Sc SCF can be effectively tuned by changing the scandium content.

  2. Effects of Mg-codoping on luminescence and scintillation properties of Ce doped Lu3(Ga,Al)5O12 single crystals

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Hiroaki; Kamada, Kei; Pejchal, Jan; Kurosawa, Shunsuke; Shoji, Yasuhiro; Yokota, Yuui; Ohashi, Yuji; Yoshikawa, Akira

    2017-03-01

    Effects of Mg co-doping on scintillation properties of Ce:Lu3(Ga,Al)5O12 (LGAG) were investigated. Mg 200 ppm co-doped Ce:LGAG single crystals were prepared by micro pulling down method. Absorption and radioluminescence spectra were measured together with several other scintillation characteristics, namely the scintillation decay and light yield to reveal the effect of Mg co-doping. Ce4+ charge transfer absorption was observed below 340 nm in Mg,Ce:LGAG which is in good agreement with previous reports for other garnet-based crystals. The scintillation decay time showed the tendency to be accelerated and the light yield was enhanced by Mg co-doping.

  3. Polishing procedure and surface characterization lead tungstate crystal scintillator Road No. 723 and No. 754

    SciTech Connect

    Kellam, M

    1996-05-01

    Step by step procedures are given for polishing the scintillator rods. A Strasbaugh spindle polishing machine was used along with visual inspection and hand polishing. Extensive data is given on pre-polish surface characterization, profilometry, microphotography, and interferometry.

  4. Scintillation properties of a 2-inch diameter KCa0.8Sr0.2I3:Eu2+ single crystal

    NASA Astrophysics Data System (ADS)

    Wu, Yuntao; Lindsey, Adam C.; Loyd, Matthew; Stand, Luis; Zhuravleva, Mariya; Koschan, Merry; Melcher, Charles L.

    2017-09-01

    Inch-sized scintillating crystals are required for practical radiation detectors such as hand-held radio-isotope identification devices. In this work, a transparent and colorless 2-inch diameter KCa0.8Sr0.2I3: 0 . 5 mo% Eu2+ single crystal was grown by the vertical Bridgman method, and the scintillation properties of a ∅ 50 mm × 45 mm long sample were evaluated. The Eu2+ 5d1- 4 f emission under X-ray excitation is centered at 472 nm. Its scintillation decay time under 137 Cs source irradiation is 2 . 37 μs, and the absolute light output is 51,000 ± 3000 photons/MeV. The energy resolution at 662 keV was evaluated for different orientations of the crystals with respect to the PMT, and the effect of 40 K background subtraction on energy resolution was evaluated. The performance of the packaged crystal was also investigated.

  5. Improvement of radiopurity level of enriched 116CdWO4 and ZnWO4 crystal scintillators by recrystallization

    NASA Astrophysics Data System (ADS)

    Barabash, A. S.; Belli, P.; Bernabei, R.; Borovlev, Yu. A.; Cappella, F.; Caracciolo, V.; Cerulli, R.; Danevich, F. A.; Incicchitti, A.; Kobychev, V. V.; Konovalov, S. I.; Laubenstein, M.; Mokina, V. M.; Polischuk, O. G.; Safonova, O. E.; Shlegel, V. N.; Tretyak, V. I.; Tupitsyna, I. A.; Umatov, V. I.; Zhdankov, V. N.

    2016-10-01

    As low as possible radioactive contamination of a detector plays a crucial role to improve sensitivity of a double beta decay experiment. The radioactive contamination of a sample of 116CdWO4 crystal scintillator by thorium was reduced by a factor ≈10, down to the level 0.01 mBq/kg (228Th), by exploiting the recrystallization procedure. The total alpha activity of uranium and thorium daughters was reduced by a factor ≈3, down to 1.6 mBq/kg. No change in the specific activity (the total α activity and 228Th) was observed in a sample of ZnWO4 crystal produced by recrystallization after removing ≈0.4 mm surface layer of the crystal.

  6. Crystal growth and spectroscopic performance of large crystalline boules of CsCaI3:Eu scintillator

    NASA Astrophysics Data System (ADS)

    Lindsey, A.; McAlexander, W.; Stand, L.; Wu, Y.; Zhuravleva, M.; Melcher, C. L.

    2015-10-01

    The crystal growth of CsCaI3:Eu with improved quality over prior efforts for use in X-ray and gamma-ray detection applications is reported. Boules were grown using the vertical Bridgman technique in quartz ampoules at 15, 22, and 35 mm diameters. CsCaI3:Eu crystals show evidence of a heavily twinned microstructure likely caused by a solid-solid phase transformation of the crystal during the cooling process. Energy resolution (FWHM) in large and small samples taken from crystalline boules varies between 13% and 4.5% for 662 keV gamma rays indicating volumetric non-uniformity. Scintillation decay time is shown to increase with volume. Proportionality of the light yield of CsCaI3:Eu is reported for the first time.

  7. Non-proportionality study of CaMoO4 and GAGG:Ce scintillation crystals using Compton coincidence technique.

    PubMed

    Kaewkhao, J; Limkitjaroenporn, P; Chaiphaksa, W; Kim, H J

    2016-09-01

    In this study, the CCT technique and nuclear instrument module (NIM) setup for the measurements of coincidence electron energy spectra of calcium molybdate (CaMoO4) and cerium doped gadolinium aluminium gallium garnet (Gd3Al2Ga3O12:Ce or GAGG:Ce) scintillation crystals were carried out. The (137)Cs irradiated gamma rays with an energy (Eγ) of 662keV was used as a radioactive source. The coincidence electron energy spectra were recorded at seven scattering angles of 30°-120°. It was found that seven corresponding electron energies were in the range of 100.5-435.4keV. The results show that, for all electron energies, the electron energy peaks of CaMoO4 crystal yielded higher number of counts than those of GAGG:Ce crystal. The electron energy resolution, the light yield and non-proportionality were also determined. It was found that the energy resolutions are inverse proportional to the square root of electron energy for both crystals. Furthermore, the results show that the light yield of GAGG:Ce crystal is much higher than that of CaMoO4 crystal. It was also found that both CaMoO4 and GAGG:Ce crystals demonstrated good proportional property in the electron energy range of 260-435.4keV. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Study of a prototype high quantum efficiency thick scintillation crystal video-electronic portal imaging device.

    PubMed

    Samant, Sanjiv S; Gopal, Arun

    2006-08-01

    Image quality in portal imaging suffers significantly from the loss in contrast and spatial resolution that results from the excessive Compton scatter associated with megavoltage x rays. In addition, portal image quality is further reduced due to the poor quantum efficiency (QE) of current electronic portal imaging devices (EPIDs). Commercial video-camera-based EPIDs or VEPIDs that utilize a thin phosphor screen in conjunction with a metal buildup plate to convert the incident x rays to light suffer from reduced light production due to low QE (<2% for Eastman Kodak Lanex Fast-B). Flat-panel EPIDs that utilize the same luminescent screen along with an a-Si:H photodiode array provide improved image quality compared to VEPIDs, but they are expensive and can be susceptible to radiation damage to the peripheral electronics. In this article, we present a prototype VEPID system for high quality portal imaging at sub-monitor-unit (subMU) exposures based on a thick scintillation crystal (TSC) that acts as a high QE luminescent screen. The prototype TSC system utilizes a 12 mm thick transparent CsI(Tl) (thallium-activated cesium iodide) scintillator for QE=0.24, resulting in significantly higher light production compared to commercial phosphor screens. The 25 X 25 cm2 CsI(Tl) screen is coupled to a high spatial and contrast resolution Video-Optics plumbicon-tube camera system (1240 X 1024 pixels, 250 microm pixel width at isocenter, 12-bit ADC). As a proof-of-principle prototype, the TSC system with user-controlled camera target integration was adapted for use in an existing clinical gantry (Siemens BEAMVIEW(PLUS)) with the capability for online intratreatment fluoroscopy. Measurements of modulation transfer function (MTF) were conducted to characterize the TSC spatial resolution. The measured MTF along with measurements of the TSC noise power spectrum (NPS) were used to determine the system detective quantum efficiency (DQE). A theoretical expression of DQE(0) was developed

  9. Study of position reconstruction of a LaBr3:Ce continuous scintillation crystal for medical applications

    NASA Astrophysics Data System (ADS)

    Fabbri, A.; Sacco, D.; Bennati, P.; Baroncelli, A.; Galasso, M.; Cinti, M. N.; Pellegrini, R.; Pani, R.; Cencelli, V. O.

    2013-12-01

    Many modern molecular imaging techniques, based on radiopharmaceuticals, can take advantage of sophisticated devices but are still based on the scintillation detector mechanism proposed by Anger. These devices can perform with millimeter spatial resolution and high detection efficiency, but the final performance is strongly affected by the algorithm used for the scintillation position detection. In this work, a detailed comparison of the effect on the imaging performances of three new position detection algorithms, in terms of spatial resolution, detection linearity and useful Field of View is performed on a prototype gamma detector. The detector, built by the authors, is based on a continuous LaBr3:Ce scintillation crystal coupled to an Hamamatsu MA-PMT H8500 and a single anode readout electronics. The experimental data are obtained scanning the detector surface with a Tc99m collimated source (0.4 mm phi) at 1.5 mm step. The overall imaging performances of the device are also tested by mean of a bar phantom. We conclude that the Anger-like algorithms give a 50% uFoV with a 1.30 mm ±0.05 mm spatial resolution while the proposed algorithms give a 80% uFoV and 1.10 mm ±0.06 mm spatial resolution.

  10. Measurements of the scintillation time constants of inorganic crystals for the development of a triple-Phoswich detector for high-energy X-ray quanta

    NASA Astrophysics Data System (ADS)

    Michelis, Thilo

    1987-04-01

    A setup for the measurement of the rise time distribution of pulses measured by a triple-Phoswich detector that is planned as component of an imaging system of a rotation-modulation telescope (RMT) was built. The principles and characteristics of scintillation crystals, scintillation detectors, and RMT's are outlined. Measurements on CsT(Tl) test crystals show a strong dependence of rise time distribution on Tl-concentration, and a clear dependence on temperature. A system for optimum light collection was developed for a Phoswich detector. The scintillation crystals NaJ(Tl) and CsJ(Na) are very suitable for a strip Phoswich. Proposals for a triple-Phoswich as detector for an RMT are given.

  11. SCINTILLATION SPECTROMETER

    DOEpatents

    Bell, P.R.; Francis, J.E.

    1960-06-21

    A portable scintillation spectrometer is described which is especially useful in radio-biological studies for determining the uptake and distribution of gamma -emitting substances in tissue. The spectrometer includes a collimator having a plurality of apertures that are hexagonal in cross section. Two crystals are provided: one is activated to respond to incident rays from the collimator; the other is not activated and shields the first from external radiation.

  12. Rare-Earth Tri-Halide Methanol-Adduct Single-Crystal Scintillators for Gamma Ray and Neutron Detection - 8/17/09

    SciTech Connect

    Boatner, Lynn A; Wisniewski, D.; Neal, John S; Bell, Zane W; Ramey, Joanne Oxendine; Kolopus, James A; Chakoumakos, Bryan C; Custelcean, Radu; Wisniewska, Monika; Peña, K. E.

    2009-01-01

    Cerium activated rare-earth tri- halides represent a well-known family of high performance inorganic rare-earth scintillators - including the high-light-yield, high-energy-resolution scintillator, cerium-doped lanthanum tribromide. These hygroscopic inorganic rare-earth halides are currently grown as single crystals from the melt - either by the Bridgman or Czochralski techniques slow and expensive processes that are frequently characterized by severe cracking of the material due to anisotropic thermal stresses and cleavage effects. We have recently discovered a new family of cerium-activated rare-earth metal organic scintillators consisting of tri-halide methanol adducts of cerium and lanthanum namely CeCl3(CH3OH)4 and LaBr3(CH3OH)4:Ce. These methanol-adduct scintillator materials can be grown near room temperature from a methanol solution, and their high solubility is consistent with the application of the rapid solution growth methods that are currently used to grow very large single crystals of potassium dihydrogen phosphate. The structures of these new rare-earth metal-organic scintillating compounds were determined by single crystal x-ray refinements, and their scintillation response to both gamma rays and neutrons, as presented here, was characterized using different excitation sources. Tri-halide methanol-adduct crystals activated with trivalent cerium apparently represent the initial example of a solution-grown rare-earth metal-organic molecular scintillator that is applicable to gamma ray, x-ray, and fast neutron detection.

  13. Search for long-lived superheavy eka-tungsten with radiopure ZnWO4 crystal scintillator

    NASA Astrophysics Data System (ADS)

    Belli, P.; Bernabei, R.; Cappella, F.; Cerulli, R.; Danevich, F. A.; Denisov, V. Yu; d'Angelo, A.; Incicchitti, A.; Kobychev, V. V.; Poda, D. V.; Polischuk, O. G.; Tretyak, V. I.

    2015-08-01

    The data collected with a radioactively pure ZnWO4 crystal scintillator (699 g) in low background measurements during 2130 h at the underground (3600 m w.e.) Laboratori Nazionali del Gran Sasso (INFN, Italy) were used to set a limit on possible concentration of superheavy eka-W (seaborgium Sg, Z = 106) in the crystal. Assuming that one of the daughters in a chain of decays of the initial Sg nucleus decays with emission of high energy α particle ({{Q}α }\\gt 8 MeV) and analyzing the high energy part of the measured α spectrum, the limit N(Sg)/N(W) \\lt 5.5× {{10}-14} atoms/atom at 90% C.L. was obtained (for Sg half-life of 109 yr). In addition, a limit on the concentration of eka-Bi was set by analysing the data collected with a large BGO scintillation bolometer in an experiment performed by another group (Cardani et al 2012 JINST 7 P10022): N(eka-Bi)/N(Bi) \\lt 1.1× {{10}-13} atoms/atom with 90% C.L. Both the limits are comparable with those obtained in recent experiments which instead look for spontaneous fission of superheavy elements or use the accelerator mass spectrometry.

  14. Luminescence and scintillation timing characteristics of (LuxGd2-x)SiO5:Ce single crystals

    NASA Astrophysics Data System (ADS)

    Yawai, Nattasuda; Chewpraditkul, Warut; Sakthong, Ongsa; Chewpraditkul, Weerapong; Wantong, Kriangkrai; Szczesniak, Tomasz; Swiderski, Lukasz; Moszynski, Marek; Sidletskiy, Oleg

    2017-02-01

    The luminescence and scintillation characteristics of cerium-doped lutetium-gadolinium orthosilicate (LuxGd2-xSiO5:Ce; x=0, 0.8, 1.8) single crystals were investigated. At 662 keV γ-rays, the light yield of 29,800±3000 ph MeV-1 obtained for Lu1.8Gd0.2SiO5:Ce is higher than that of 20,200±2000 and 11,800±1200 ph MeV-1 obtained for Lu0.8Gd1.2SiO5:Ce and Gd2SiO5:Ce, respectively. The fast component decay time of 32, 18 and 17 ns was measured in the scintillation decay of Gd2SiO5:Ce, Lu0.8Gd1.2SiO5:Ce and Lu1.8Gd0.2SiO5:Ce, respectively. The coincidence time spectra for 511 keV annihilation quanta were measured in reference to a fast BaF2 detector and time resolution was discussed in terms of a number of photoelectrons and decay time of the fast component. The mass attenuation coefficient for studied crystals at 60 and 662 keV γ-rays was also evaluated and discussed.

  15. Luminescence and light yield of (Gd2Y)(Ga3Al2)O12:Pr3+ single crystal scintillators

    NASA Astrophysics Data System (ADS)

    Lertloypanyachai, Prapon; Pathumrangsan, Nichakorn; Sreebunpeng, Krittiya; Pattanaboonmee, Nakarin; Chewpraditkul, Weerapong; Yoshikawa, Akira; Kamada, Kei; Nikl, Martin

    2017-06-01

    Praseodymium-doped (Gd2Y)(Ga3Al2)O12 (GYGAG: Pr) single crystals are grown by the micro-pulling down method with different Pr concentrations. The energy transfer process between Pr3+ and Gd3+ is investigated by photoluminescence excitation (PLE) and emission (PL) spectra measurements. Photoelectron yield measurements are carried out using photomultiplier. At 662 keV γ-rays, photoelectron yield of 2520 phe/MeV obtained for the GYGAG: Pr (0.01%) sample is larger than that of 1810 phe/MeV obtained for BGO crystal. Light yield degradation for the GYGAG: Pr scintillators is presumably due to the energy transfer from 5d state of Pr3+ to 4f state of Gd3+ together with the concentration quenching in the Gd3+-sublattice.

  16. Studying the energy dependence of intrinsic conversion efficiency of single crystal scintillators under X-ray excitation

    NASA Astrophysics Data System (ADS)

    Kalyvas, N.; Valais, I.; David, S.; Michail, Ch.; Fountos, G.; Liaparinos, P.; Kandarakis, I.

    2014-05-01

    Single crystal scintilators are used in various radiation detectors applications. The efficiency of the crystal can be determined by the Detector Optical Gain (DOG) defined as the ratio of the emitted optical photon flux over the incident radiation photons flux. A parameter affecting DOG is the intrinsic conversion efficiency ( n C ) giving the percentage of the X-ray photon power converted to optical photon power. n C is considered a constant value for X-ray energies in the order of keV although a non-proportional behavior has been reported. In this work an analytical model, has been utilized to single crystals scintillators GSO:Ce, LSO:Ce and LYSO:Ce to examine whether the intrinsic conversion efficiency shows non proportional behavior under X-ray excitation. DOG was theoretically calculated as a function of the incident X-ray spectrum, the X-ray absorption efficiency, the energy of the produced optical photons and the light transmission efficiency. The theoretical DOG values were compared with experimental data obtained by irradiating the crystals with X-rays at tube voltages from 50 to 140 kV and by measuring the light energy flux emitted from the irradiated screen. An initial value for n C (calculated from literature data) was assumed for the X-ray tube voltage of 50 kV. For higher X-ray tube voltages the optical photon propagation phenomena was assumed constant and any deviations between experimental and theoretical data were associated with changes in the intrinsic conversion efficiency. The experimental errors were below 7% for each experimental setup. The behavior of n C values for LSO:Ce and LYSO:Ce were found very similar, i.e., ranging with values from 0.089 at 50 kV to 0.015 at 140 kV, while for GSO:Ce, n C demonstrated a peak at 80 kV.

  17. Radiation Detection and Classification of Heavy Oxide Inorganic Scintillator Crystals for Detection of Fast Neutrons

    DTIC Science & Technology

    2016-06-01

    and alkali -halide scintillators for potential use in neutron and gamma detection systems.” M.S. thesis, Dept. Physics, Naval Posgraduate School...assets.newport.com/webDocuments- EN/images/2151_And_2153_User_Manual_RevC.pdf Accessed Apr. 1, 2016. [25] Metal package PMT with cooler photosensor modules

  18. Low radioactivity CaF{sub 2} scintillator crystals for CANDLES

    SciTech Connect

    Ogawa, I.; Umehara, S.; Ito, G.; Yasuda, K.; Kakubata, H.; Miyashita, M.; Matsuoka, K.; Nomachi, M.; Kishimoto, T.; Fushimi, K.; Hazama, R.; Ohsumi, H.; Okada, K.; Tamagawa, Y.; Yoshida, S.

    2011-04-27

    CANDLES is the project to search for neutrinoless double beta (0{nu}{beta}{beta}) decay of {sup 48}Ca by using CaF{sub 2} scintillators. The observation of 0{nu}{beta}{beta} decay will prove the existence of massive Majorana neutrinos. Expected performances and current status of the CANDLES system are described.

  19. Crystal structure, electronic structure, temperature-dependent optical and scintillation properties of CsCe2Br7

    DOE PAGES

    Wu, Yuntao; Shi, Hongliang; Chakoumakos, Bryan C.; ...

    2015-10-05

    CsCe2Br7 is a self-activated inorganic scintillator that shows promising performance, but the understanding of the important structure-property relationships is lacking. In this work, we conduct a comprehensive study on CCsCe2Br7. The crystal structure of CsCe2Br7 is refined using single crystal X-ray study for the first time. It crystallizes into the orthorhombic crystal system with Pmnb space group. Its electronic structure is revealed by Density Functional Theory (DFT) calculations. Two cerium emission centers are identified and the energy barriers related to the thermal quenching to 4f ground states of Ce3+ for these two Ce centers are evaluated. CsCe2Br7 single crystal hasmore » better light yield and energy resolution than CsCe2Cl7, but with an additional slow decay component of 1.7 s. The existence of a deep trap with a depth of 0.9 eV in CsCe2Cl7 contributes to its higher afterglow level in comparison to that of CsCe2Br7. The most possible point defects in CsCe2Cl7 and CsCe2Br7 are proposed by considering the vapour pressure in the growth atmosphere upon melting point.« less

  20. In situ diagnostics of the crystal-growth process through neutron imaging: application to scintillators

    SciTech Connect

    Tremsin, Anton S.; Makowska, Małgorzata G.; Perrodin, Didier; Shalapska, Tetiana; Khodyuk, Ivan V.; Trtik, Pavel; Boillat, Pierre; Vogel, Sven C.; Losko, Adrian S.; Strobl, Markus; Kuhn, L. Theil; Bizarri, Gregory A.; Bourret-Courchesne, Edith D.

    2016-04-12

    Neutrons are known to be unique probes in situations where other types of radiation fail to penetrate samples and their surrounding structures. In this paper it is demonstrated how thermal and cold neutron radiography can provide time-resolved imaging of materials while they are being processed (e.g.while growing single crystals). The processing equipment, in this case furnaces, and the scintillator materials are opaque to conventional X-ray interrogation techniques. The distribution of the europium activator within a BaBrCl:Eu scintillator (0.1 and 0.5% nominal doping concentrations per mole) is studiedin situduring the melting and solidification processes with a temporal resolution of 5–7 s. The strong tendency of the Eu dopant to segregate during the solidification process is observed in repeated cycles, with Eu forming clusters on multiple length scales (only for clusters larger than ~50 µm, as limited by the resolution of the present experiments). It is also demonstrated that the dopant concentration can be quantified even for very low concentration levels (~0.1%) in 10 mm thick samples. The interface between the solid and liquid phases can also be imaged, provided there is a sufficient change in concentration of one of the elements with a sufficient neutron attenuation cross section. Tomographic imaging of the BaBrCl:0.1%Eu sample reveals a strong correlation between crystal fractures and Eu-deficient clusters. The results of these experiments demonstrate the unique capabilities of neutron imaging forin situdiagnostics and the optimization of crystal-growth procedures.

  1. An algorithm for automatic crystal identification in pixelated scintillation detectors using thin plate splines and Gaussian mixture models

    NASA Astrophysics Data System (ADS)

    Schellenberg, Graham; Stortz, Greg; Goertzen, Andrew L.

    2016-02-01

    A typical positron emission tomography detector is comprised of a scintillator crystal array coupled to a photodetector array or other position sensitive detector. Such detectors using light sharing to read out crystal elements require the creation of a crystal lookup table (CLUT) that maps the detector response to the crystal of interaction based on the x-y position of the event calculated through Anger-type logic. It is vital for system performance that these CLUTs be accurate so that the location of events can be accurately identified and so that crystal-specific corrections, such as energy windowing or time alignment, can be applied. While using manual segmentation of the flood image to create the CLUT is a simple and reliable approach, it is both tedious and time consuming for systems with large numbers of crystal elements. In this work we describe the development of an automated algorithm for CLUT generation that uses a Gaussian mixture model paired with thin plate splines (TPS) to iteratively fit a crystal layout template that includes the crystal numbering pattern. Starting from a region of stability, Gaussians are individually fit to data corresponding to crystal locations while simultaneously updating a TPS for predicting future Gaussian locations at the edge of a region of interest that grows as individual Gaussians converge to crystal locations. The algorithm was tested with flood image data collected from 16 detector modules, each consisting of a 409 crystal dual-layer offset LYSO crystal array readout by a 32 pixel SiPM array. For these detector flood images, depending on user defined input parameters, the algorithm runtime ranged between 17.5-82.5 s per detector on a single core of an Intel i7 processor. The method maintained an accuracy above 99.8% across all tests, with the majority of errors being localized to error prone corner regions. This method can be easily extended for use with other detector types through adjustment of the initial

  2. An algorithm for automatic crystal identification in pixelated scintillation detectors using thin plate splines and Gaussian mixture models.

    PubMed

    Schellenberg, Graham; Stortz, Greg; Goertzen, Andrew L

    2016-02-07

    A typical positron emission tomography detector is comprised of a scintillator crystal array coupled to a photodetector array or other position sensitive detector. Such detectors using light sharing to read out crystal elements require the creation of a crystal lookup table (CLUT) that maps the detector response to the crystal of interaction based on the x-y position of the event calculated through Anger-type logic. It is vital for system performance that these CLUTs be accurate so that the location of events can be accurately identified and so that crystal-specific corrections, such as energy windowing or time alignment, can be applied. While using manual segmentation of the flood image to create the CLUT is a simple and reliable approach, it is both tedious and time consuming for systems with large numbers of crystal elements. In this work we describe the development of an automated algorithm for CLUT generation that uses a Gaussian mixture model paired with thin plate splines (TPS) to iteratively fit a crystal layout template that includes the crystal numbering pattern. Starting from a region of stability, Gaussians are individually fit to data corresponding to crystal locations while simultaneously updating a TPS for predicting future Gaussian locations at the edge of a region of interest that grows as individual Gaussians converge to crystal locations. The algorithm was tested with flood image data collected from 16 detector modules, each consisting of a 409 crystal dual-layer offset LYSO crystal array readout by a 32 pixel SiPM array. For these detector flood images, depending on user defined input parameters, the algorithm runtime ranged between 17.5-82.5 s per detector on a single core of an Intel i7 processor. The method maintained an accuracy above 99.8% across all tests, with the majority of errors being localized to error prone corner regions. This method can be easily extended for use with other detector types through adjustment of the initial

  3. Comparative Characterization Study of a LaBr3(Ce) Scintillation Crystal in Two Surface Wrapping Scenarios: Absorptive and Reflective

    PubMed Central

    Aldawood, Saad; Castelhano, Ines; Gernhäuser, Roman; Van Der Kolff, Hugh; Lang, Christian; Liprandi, Silvia; Lutter, Rudolf; Maier, Ludwig; Marinšek, Tim; Schaart, Dennis R.; Parodi, Katia; Thirolf, Peter G.

    2015-01-01

    The properties of a 50 mm × 50 mm × 30 mm monolithic LaBr3:Ce scintillator crystal coupled to a position-sensitive multi-anode photomultiplier (PMT, Hamamatsu H9500), representing the absorbing detector of a Compton camera under study for online ion (proton) beam range verification in hadron therapy, was evaluated in combination with either absorptive or reflective crystal surface coating. This study covered an assessment of the energy and position-dependent energy resolution, exhibiting a factor of 2.5–3.5 improvement for the reflectively wrapped crystal at 662 keV. The spatial dependency was investigated using a collimated 137Cs source, showing a steep degradation of the energy resolution at the edges and corners of the absorptively wrapped crystal. Furthermore, the time resolution was determined to be 273 ps (FWHM) and 536 ps (FWHM) with reflective and absorptive coating, respectively, using a 60Co source. In contrast, the light spread function (LSF) of the light amplitude distribution on the PMT segments improved for the absorptively wrapped detector. Both wrapping modalities showed almost no differences in the energy-dependent photopeak detection efficiency. PMID:26697405

  4. Crystal growth and characterization of Eu2+ doped RbCaX3 (X = Cl, Br) scintillators

    NASA Astrophysics Data System (ADS)

    Rebrova, N. V.; Grippa, A. Yu.; Pushak, A. S.; Gorbacheva, T. E.; Pedash, V. Yu.; Viagin, O. G.; Cherginets, V. L.; Tarasov, V. A.; Vistovskyy, V. V.; Vas'kiv, A. P.; Myagkota, S. V.

    2017-05-01

    The single crystals of RbCa1-yEuyX3 (X = Cl, Br; y = 0.03, 0.05, 0.08) were obtained by the Bridgman-Stockbarger technique. The luminescent and luminescent-kinetic properties of RbCaCl3:5%Eu and RbCaBr3:5%Eu under photo- and X-ray excitation (35-40 keV) at 77 and 293 K were studied. The luminescence spectra of the crystals exhibit one dominant band which corresponds to Eu2+ emission. The scintillation properties of all the grown crystals under 137Cs 662 keV gamma-ray excitation were investigated. The maximal values of relative light output were found for RbCaCl3:8%Eu2+ and RbCaBr3:8%Eu2+ which are approximately equal to 50% and 77% of NaI:Tl with decay time 2.7 and 3.6 μs respectively. The hygroscopicity of the crystals was estimated.

  5. Bridgman Growth of Large SrI2:Eu2+ Single Crystals: A High-performance Scintillator for Radiation Detection Applications

    SciTech Connect

    Boatner, Lynn A; Ramey, Joanne Oxendine; Kolopus, James A; Hawrami, Rastgo; Higgins, William; Van Loef, Edgar; Glodo, J.; Shah, Kanai; Bhattacharya, P.; Tupitsyn, E; Groza, Michael; Burger, Arnold

    2013-01-01

    Single-crystal strontium iodide (SrI2) doped with relatively high levels (e.g., 3 - 6 %) of Eu2+ exhibits characteristics that make this material superior, in a number of respects, to other scintillators that are currently used for radiation detection. Specifically, SrI2:Eu2+ has a light yield that is significantly higher than LaBr3:Ce3+ -a currently employed commercial high-performance scintillator. Additionally, SrI2:Eu2+ is characterized by an energy resolution as high as 2.6% at the 137Cs gamma-ray energy of 662 keV, and there is no radioactive component in SrI2:Eu2+ - unlike LaBr3:Ce3+ that contains 138La. The Ce3+-doped LaBr3 decay time is, however, faster (30 nsec) than the 1.2 sec decay time of SrI2:Eu2+. Due to the relatively low melting point of strontium iodide (~515 oC), crystal growth can be carried out in quartz crucibles by the vertical Bridgman technique. Materials-processing and crystal-growth techniques that are specific to the Bridgman growth of europium-doped strontium iodide scintillators are described here. These techniques include the use of a porous quartz frit to physically filter the molten salt from a quartz antechamber into the Bridgman growth crucible and the use of a bent or bulb grain selector design to suppress multiple grain growth. Single crystals of SrI2:Eu2+ scintillators with good optical quality and scintillation characteristics have been grown in sizes up to 5.0 cm in diameter by applying these techniques. Other aspects of the SrI2:Eu2+ crystal-growth methods and of the still unresolved crystal-growth issues are described here.

  6. Bridgman growth of large SrI2:Eu2+ single crystals: A high-performance scintillator for radiation detection applications

    NASA Astrophysics Data System (ADS)

    Boatner, L. A.; Ramey, J. O.; Kolopus, J. A.; Hawrami, R.; Higgins, W. M.; van Loef, E.; Glodo, J.; Shah, K. S.; Rowe, Emmanuel; Bhattacharya, Pijush; Tupitsyn, Eugene; Groza, Michael; Burger, Arnold; Cherepy, N. J.; Payne, S. A.

    2013-09-01

    Single-crystal strontium iodide (SrI2) doped with relatively high levels (e.g., 3-6%) of Eu2+ exhibits characteristics that make this material superior, in a number of respects, to other scintillators that are currently used for radiation detection. Specifically, SrI2:Eu2+ has a light yield that is significantly higher than LaBr3:Ce3+—a currently employed commercial high-performance scintillator. Additionally, SrI2:Eu2+ is characterized by an energy resolution as high as 2.6% at the 137Cs gamma-ray energy of 662 keV, and there is no radioactive component in SrI2:Eu2+—unlike LaBr3:Ce3+ that contains 138La. The Ce3+-doped LaBr3 decay time is, however, faster (30 ns) than the 1.2 μs decay time of SrI2:Eu2+. Due to the relatively low melting point of strontium iodide (˜515 °C), crystal growth can be carried out in quartz crucibles by the vertical Bridgman technique. Materials-processing and crystal-growth techniques that are specific to the Bridgman growth of europium-doped strontium iodide scintillators are described here. These techniques include the use of a porous quartz frit to physically filter the molten salt from a quartz antechamber into the Bridgman growth crucible and the use of a "bent" or "bulb" grain selector design to suppress multiple grain growth. Single crystals of SrI2:Eu2+ scintillators with good optical quality and scintillation characteristics have been grown in sizes up to 5.0 cm in diameter by applying these techniques. Other aspects of the SrI2:Eu2+ crystal-growth methods and of the still unresolved crystal-growth issues are described here.

  7. [Evaluation of efficiency of a multi-crystal scintillation camera Digirad 2020tc Imager using a solid-state detectors].

    PubMed

    Narita, H; Kawaida, Y; Ooshita, T; Itoh, T; Tsuchida, D; Fukumitsu, N; Mori, Y; Makino, M

    2001-07-01

    Digirad 2020tc Imager is the movable scintillation camera, consisting of combining multi-crystal scintillators (CsI(Tl)) and photo-diodes. Total numbers of element are 4096, which are further divided into 16 x 16 modules. Each module contains 4 x 4 elements. We have examined Digirad 2020tc according to NEMA (National Electrical Manufactures Association), and the following results are obtained; the maximum count rate; 221 kcps, total system uniformity; 1.3% (integral uniformity), 0.9% (differential uniformity), system spatial resolution; 6.97 +/- 0.72 mm (the LEHR collimator to 99mTc source at 10 cm), intrinsic energy resolution; 12.8%, total system sensitivity; 3270.8 cpm/MBq (with LEHR collimator using 99mTc source at 10 cm). Further more, we determined the contrast of an imaging using the pin-hole (100 microns phi) 99mTc source in order to know the signal per noise (S/N) ratio among the pixels (S/N; 93.4 +/- 46.2 (first pixels)). Although the physical dimension of the camera has a smaller field of view, comparing with the standard camera, Digirad 2020tc has the equivalent characteristics as well as that of the standard camera and its field view is enough to measure the adult lung perfusion using a diverging collimator. We will further examine Digirad 2020tc with its movable portability and expect applications in nuclear medicine.

  8. Investigation of crystal surface finish and geometry on single LYSO scintillator detector performance for depth-of-interaction measurement with silicon photomultipliers

    NASA Astrophysics Data System (ADS)

    Bircher, Chad; Shao, Yiping

    2012-11-01

    Depth of Interaction (DOI) information can improve quality of reconstructed images acquired from Positron Emission Tomography (PET), especially in high resolution and compact scanners dedicated for breast, brain, or small animal imaging applications. Additionally, clinical scanners with time of flight capability can also benefit from DOI information. One of the most promising methods of determining DOI in a crystal involves reading the signal from two ends of a scintillation crystal, and calculating the signal ratio between the two detectors. This method is known to deliver a better DOI resolution with rough crystals compared to highly polished crystals. However, what is still not well studied is how much of a tradeoff is involved between spatial, energy, temporal, and DOI resolutions as a function of the crystal surface treatment and geometry with the use of Silicon Photomultipliers (SiPM) as the photo detectors. This study investigates the effects of different crystal surface finishes and geometries on energy, timing and DOI resolutions at different crystal depths. The results show that for LYSO scintillators of 1.5×1.5×20 mm3 and 2×2×20 mm3 with their surfaces finished from 0.5 to 30 μm roughness, almost the same energy and coincidence timing resolutions were maintained, around 15% and 2.4 ns, respectively across different crystal depths, while the DOI resolutions were steadily improved from worse than 5 mm to better than 2 mm. They demonstrate that crystal roughness, with proper surface preparing, does not have a significant effect on the energy and coincidence timing resolutions in the crystals examined, and there does not appear to be a tradeoff between improving DOI resolution and degrading other detector performances. These results will be valuable to guide the selection of crystal surface conditions for developing a DOI measurable PET detector with a full array of LYSO scintillators coupled to SiPM arrays.

  9. Investigation of Crystal Surface Finish and Geometry on Single LYSO Scintillator Detector Performance for Depth-of-Interaction Measurement with Silicon Photomultipliers.

    PubMed

    Bircher, Chad; Shao, Yiping

    2012-11-21

    Depth of Interaction (DOI) information can improve quality of reconstructed images acquired from Positron Emission Tomography (PET), especially in high resolution and compact scanners dedicated for breast, brain, or small animal imaging applications. Additionally, clinical scanners with time of flight capability can also benefit from DOI information. One of the most promising methods of determining DOI in a crystal involves reading the signal from two ends of a scintillation crystal, and calculating the signal ratio between the two detectors. This method is known to deliver a better DOI resolution with rough crystals compared to highly polished crystals. However, what is still not well studied is how much of a tradeoff is involved between spatial, energy, temporal, and DOI resolutions as a function of the crystal surface treatment and geometry with the use of Silicon Photomultipliers (SiPM) as the photo detectors. This study investigates the effects of different crystal surface finishes and geometries on energy, timing and DOI resolutions at different crystal depths. The results show that for LYSO scintillators of 1.5×1.5×20 mm(3) and 2×2×20 mm(3) with their surfaces finished from 0.5 to 30 micron roughness, almost the same energy and coincidence timing resolutions were maintained, around 15% and 2.4 ns respectively across different crystal depths, while the DOI resolutions were steadily improved from worse than 5 mm to better than 2 mm. They demonstrate that crystal roughness, with proper surface preparing, does not have a significant effect on the energy and coincidence timing resolutions in the crystals examined, and there does not appear to be a tradeoff between improving DOI resolution and degrading other detector performances. These results will be valuable to guide the selection of crystal surface conditions for developing a DOI measurable PET detector with a full array of LYSO scintillators coupled to SiPM arrays.

  10. Investigation of Crystal Surface Finish and Geometry on Single LYSO Scintillator Detector Performance for Depth-of-Interaction Measurement with Silicon Photomultipliers

    PubMed Central

    Bircher, Chad

    2012-01-01

    Depth of Interaction (DOI) information can improve quality of reconstructed images acquired from Positron Emission Tomography (PET), especially in high resolution and compact scanners dedicated for breast, brain, or small animal imaging applications. Additionally, clinical scanners with time of flight capability can also benefit from DOI information. One of the most promising methods of determining DOI in a crystal involves reading the signal from two ends of a scintillation crystal, and calculating the signal ratio between the two detectors. This method is known to deliver a better DOI resolution with rough crystals compared to highly polished crystals. However, what is still not well studied is how much of a tradeoff is involved between spatial, energy, temporal, and DOI resolutions as a function of the crystal surface treatment and geometry with the use of Silicon Photomultipliers (SiPM) as the photo detectors. This study investigates the effects of different crystal surface finishes and geometries on energy, timing and DOI resolutions at different crystal depths. The results show that for LYSO scintillators of 1.5×1.5×20 mm3 and 2×2×20 mm3 with their surfaces finished from 0.5 to 30 micron roughness, almost the same energy and coincidence timing resolutions were maintained, around 15% and 2.4 ns respectively across different crystal depths, while the DOI resolutions were steadily improved from worse than 5 mm to better than 2 mm. They demonstrate that crystal roughness, with proper surface preparing, does not have a significant effect on the energy and coincidence timing resolutions in the crystals examined, and there does not appear to be a tradeoff between improving DOI resolution and degrading other detector performances. These results will be valuable to guide the selection of crystal surface conditions for developing a DOI measurable PET detector with a full array of LYSO scintillators coupled to SiPM arrays. PMID:23087497

  11. Alpha-gamma pulse-shape discrimination in Gd3Al2Ga3O12 (GAGG):Ce3+ crystal scintillator using shape indicator

    NASA Astrophysics Data System (ADS)

    Tamagawa, Yoichi; Inukai, Yuji; Ogawa, Izumi; Kobayashi, Masaaki

    2015-09-01

    The pulse-shape discrimination (PSD) in a GAGG single-crystal scintillator was studied by using a shape indicator (SI) parameter of the optimal digital filter method. SI is one of the most useful PSD methods that use typical pulse shapes. Excellent discrimination between 0.662 MeV γ-rays and 5.48 MeV α-rays was achieved. For a cut at SI=0.0056, 99.95% of the γ-rays and only 0.22% of the α-rays were retained. Selection of background events (γ and α) in the GAGG scintillator was achieved by using the PSD method.

  12. Improvement of the growth of Li4SiO4 single crystals for neutron detection and their scintillation and luminescence properties

    NASA Astrophysics Data System (ADS)

    Pejchal, Jan; Babin, Vladimir; Beitlerova, Alena; Kurosawa, Shunsuke; Yokota, Yuui; Yoshikawa, Akira; Nikl, Martin

    2017-01-01

    We have investigated Li4SiO4 scintillation crystals for their possible application in neutron detection due to high Li content and low density of 2.35 g/cm3. The micro-pulling-down method employing the Ir crucible and afterheater was optimized for crystal growth of Li4SiO4 taking into account the Li evaporation. To grow high-quality crack-free single crystals, the heating power was increased to establish milder temperature gradient, thicker meniscus, smaller crystal diameter and resulting smaller stress in the as-grown crystals. The undoped, Ti-, Cr-, and Al- doped crystals were prepared and studied. Radioluminescence measurements under X-ray excitation showed quite high overall scintillation efficiency of the Ti-doped sample reaching as high as 250% of that of Bi4Ge3O12 reference scintillator. The emission spectrum was dominated by one broad band peaking at 350 nm related to Ti4+ impurity. Reasonable light yield of 10000 photons/neutron was found. However, its long decay time of 54 μs might be a limitation especially for high counting rate applications. The overall scintillation efficiency of the Cr3+ sample was much lower and the spectrum shows one broad peak at 463 nm which does not correspond to Cr3+ luminescence. The radioluminescence spectrum of the Al-doped sample resembled to that of the Ti-doped one, just its magnitude is considerably lower, which was explained by Ti contamination. Peculiarities and optimization of crystal growth and a preliminary sketch of luminescence mechanisms and dopant incorporation are discussed.

  13. Investigations of Ba{sub 3}BP{sub 3}O{sub 12}:Eu{sup 2+} single crystal as a scintillator

    SciTech Connect

    Zhang, Zhi-Jun; Hu, Guan-Qin; Wang, Hong; Zhu, Lin-Lin; Zhao, Jing-Tai

    2014-04-01

    Highlights: • Eu{sup 2+}-activated Ba{sub 3}BP{sub 3}O{sub 12} single crystals have been grown by the top-seeded solution growth method (TSSG) for the first time. • Ba{sub 3}BP{sub 3}O{sub 12}:Eu{sup 2+} single crystal exhibits wide transparency in the wavelength range from 250 to 700 nm. • Ba{sub 3}BP{sub 3}O{sub 12}:Eu{sup 2+} single crystal shows high overall scintillation efficiency (1.8 times of BGO) and moderate decay time (860 ns). - Abstract: Single crystals of Ba{sub 3}BP{sub 3}O{sub 12}:Eu{sup 2+} with high optical quality have been grown by the top-seeded solution growth (TSSG) method using BPO{sub 4}–NaF mixture as the flux. Ba{sub 3}BP{sub 3}O{sub 12}:Eu{sup 2+} single crystal exhibits wide transparency in the wavelength range from 250 to 700 nm, and shows a broad emission band in the wavelength range of 350–650 nm when excited by X-ray radiation. The overall scintillation efficiency is about 1.8 times of that of BGO crystal under the same conditions. Its room temperature fluorescence decay curve exhibits a single-exponent shape with decay time of about 860 ns. It is worth noting that Ba{sub 3}BP{sub 3}O{sub 12}:Eu{sup 2+} single crystal may be of great interest for applications in the field of scintillation materials considering its scintillation properties, as well as the good chemical stability.

  14. Time walk correction for TOF-PET detectors based on a monolithic scintillation crystal coupled to a photosensor array

    NASA Astrophysics Data System (ADS)

    Vinke, R.; Löhner, H.; Schaart, D. R.; van Dam, H. T.; Seifert, S.; Beekman, F. J.; Dendooven, P.

    2010-09-01

    When optimizing the timing performance of a time-of-flight positron emission tomography (TOF-PET) detector based on a monolithic scintillation crystal coupled to a photosensor array, time walk as a function of annihilation photon interaction location inside the crystal needs to be considered. In order to determine the 3D spatial coordinates of the annihilation photon interaction location, a maximum likelihood estimation algorithm was developed, based on a detector characterization by a scan of a 511 keV photon beam across the front and one of the side surfaces of the crystal. The time walk effect was investigated using a 20 mm×20 mm×12 mm LYSO crystal coupled to a fast 4×4 multi-anode photomultiplier tube (MAPMT). In the plane parallel to the photosensor array, a spatial resolution of 2.4 mm FWHM is obtained. In the direction perpendicular to the MAPMT (depth-of-interaction, DOI), the resolution ranges from 2.3 mm FWHM near the MAPMT to 4 mm FWHM at a distance of 10 mm. These resolutions are uncorrected for the ˜1 mm beam diameter. A coincidence timing resolution of 358 ps FWHM is obtained in coincidence with a BaF 2 detector. A time walk depending on the 3D annihilation photon interaction location is observed. Throughout the crystal, the time walk spans a range of 100 ps. Calibration of the time walk vs. interaction location allows an event-by-event correction of the time walk.

  15. Crystal growth and optical properties of indium doped LiCaAlF6 scintillator single crystals

    NASA Astrophysics Data System (ADS)

    Tanaka, Chieko; Yokota, Yuui; Kurosawa, Shunsuke; Yamaji, Akihiro; Jary, Vitezslav; Babin, Vladimir; Pejchal, Jan; Ohashi, Yuji; Kamada, Kei; Nikl, Martin; Yoshikawa, Akira

    2017-03-01

    The In-doped LiCaAlF6 [In:LiCAF] single crystals were grown by the micro-pulling-down (μ-PD) method, and the phases, chemical compositions, transmittance and radioluminescence spectra were investigated. All the grown crystals showed high transparency and single phase of LiCAF without visible cracks and inclusions except for the end part of In2%:LiCAF crystal which included the impurity phase. In the radioluminescence spectra of the In:LiCAF crystals under X-ray irradiation, the emission peak around 750 nm was revealed.

  16. Assessing the performance under ionising radiation of lead tungstate scintillators for EM calorimetry in the CLAS12 Forward Tagger

    NASA Astrophysics Data System (ADS)

    Fegan, S.; Auffray, E.; Battaglieri, M.; Buchanan, E.; Caiffi, B.; Celentano, A.; Colaneri, L.; D`Angelo, A.; De Vita, R.; Dormenev, V.; Fanchini, E.; Lanza, L.; Novotny, R. W.; Parodi, F.; Rizzo, A.; Sokhan, D.; Tarasov, I.; Zonta, I.

    2015-07-01

    The well-established technology of electromagnetic calorimetry using Lead Tungstate crystals has recently seen an upheaval, with the closure of one of the most experienced large-scale suppliers of such crystals, the Bogoroditsk Technical Chemical Plant (BTCP), which was instrumental in the development of mass production procedures for PWO-II, the current benchmark for this scintillator. Obtaining alternative supplies of Lead Tungstate crystals matching the demanding specifications of contemporary calorimeter devices now presents a significant challenge to detector research and development programmes. In this paper we describe a programme of assessment carried out for the selection, based upon the performance under irradiation, of Lead Tungstate crystals for use in the Forward Tagger device, part of the CLAS12 detector in Hall B at Jefferson Lab. The crystals tested were acquired from SICCAS, the Shanghai Institute of Ceramics, Chinese Academy of Sciences. The tests performed are intended to maximise the performance of the detector within the practicalities of the crystal manufacturing process. Results of light transmission, before and after gamma ray irradiation, are presented and used to calculate dk, the induced radiation absorption coefficient, at 420 nm, the peak of the Lead Tungstate emission spectrum. Results for the SICCAS crystals are compared with identical measurements carried out on Bogoroditsk samples, which were acquired for the Forward Tagger development program before the closure of the facility. Also presented are a series of tests performed to determine the feasibility of recovering radiation damage to the crystals using illumination from an LED, with such illumination available in the Forward Tagger from a light monitoring system integral to the detector.

  17. Growth of 2 Inch Eu-doped SrI2 single crystals for scintillator applications

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Akira; Shoji, Yasuhiro; Yokota, Yuui; Kurosawa, Shunsuke; Hayasaka, Shoki; Chani, Valery I.; Ito, Tomoki; Kamada, Kei; Ohashi, Yuji; Kochurikhin, Vladimir

    2016-10-01

    A vertical Bridgman (VB) crystal growth process was established using modified micro-pulling-down (μ-PD) crystal growth system with a removable chamber that was developed for the growth of deliquescent halide single crystals because conventional μ-PD method does not allow growth of large bulk single crystals. Eu:SrI2 crystals were grown from the melt of (Sr0.98Eu0.02)I2 composition using carbon crucibles. Undoped μ-PD SrI2 crystals were used as seeds that were affixed to the bottom of the crucible. All the preparations preceding the growths and the hot zone assembling were performed in a glove box with Ar gas. Then the removable chamber was taken out of the glove box, attached to the μ-PD system, connected with a Turbo Molecular pump, and evacuated down to 10-4 Pa at 300 °C. After the baking procedure, high purity Ar gas (6N) was injected into the chamber. The crucible was heated by a high frequency induction coil up to the melting point of Eu:SrI2. After melting the starting materials, the crucible was displaced in downward direction for the crystal growth and then cooled down to room temperature. Thus, 2 in. and crack-free Eu:SrI2 bulk crystals were produced. The crystals had high transparency and did not contain any visible inclusions. The crystals were cut and polished in the glove box and then sealed in an aluminum container with an optical window for characterization. The details of the crystal growth are discussed.

  18. Search for double beta processes in {sup 106}Cd with enriched {sup 106}CdWO{sub 4} crystal scintillator in coincidence with four crystals HPGe detector

    SciTech Connect

    Danevich, F. A. Chernyak, D. M.; Mokina, V. M.; Belli, P.; Bernabei, R.; D’Angelo, S.; Brudanin, V. B.; Cappella, F.; Caracciolo, V.; Cerulli, R.; Laubenstein, M.; Incicchitti, A.; Poda, D. V.; Polischuk, O. G.; Tretyak, V. I.; Tupitsyna, I. A.

    2015-10-28

    A radiopure cadmium tungstate crystal scintillator, enriched in {sup 106}Cd ({sup 106}CdWO{sub 4}), was used to search for double beta decay processes in {sup 106}Cd in coincidence with an ultra-low background set-up containing four high purity germanium (HPGe) detectors in a single cryostat. The experiment has been completed after 13085 h of data taking. New improved limits on most of the double beta processes in {sup 106}Cd have been set on the level of 10{sup 20}−10{sup 21} yr. Tn particular, the half-life limit on the two neutrino electron capture with positron emission, T{sub 1/2} ≥ 1.8 × 10{sup 21} yr, reached the region of theoretical predictions.

  19. Ax-Pet a Demonstrator for PET Imaging Using Long Axially Oriented Scintillating Crystals

    NASA Astrophysics Data System (ADS)

    Beltrame, Paolo; Braem, André; Fanti, Viviana; Joram, Christian; Schneider, Thomas; Séguinot, Jacques; Casella, Chiara; Dissertori, Günther; Djambazov, Lubomir; Lustermann, Werner; Nessi-Tedaldi, Francesca; Pauss, Felicitas; Schinzel, Dietrich; Solevi, Paola; Oliver, Josep F.; Rafecas, Magdalena; de Leo, Raffaele; Nappi, Eugenio; Chesi, Enrico; Cochran, Eric; Honscheid, Klaus; Kagan, Harris; Rudge, Alan; Smith, Shane; Weilhammer, Peter; Johnson, Ian; Renker, Dieter; Clinthorne, Neal; Huh, Sam; Bolle, Erlend; Stapnes, Steinar; Meddi, Franco

    2010-04-01

    Two PET scanner modules have been built in order to demonstrate the AX-PET concept in a phantom test. Each module comprises 6 layers of 8 LYSO crystals (3 × 3 × 100) mm3 orthogonally interleaved with layers of 26 wave length shifting strips (WLS) with dimensions (0.9 × 3 × 40) mm3. The spatial resolution is defined by the dimensions of the crystals and WLS strips, while the sensitivity depends on the number of crystal layers. According to MC simulations, the sensitivity will be increased further by reconstructing Compton interactions. Crystals and WLS strips are read out by MPPCs. First module tests yield an energy resolution of the LYSO crystals of 12.33 % and 12.46 % FWHM and a spatial resolution of the WLS strips of (1.68 ± 0.25) mm FWHM. Special simulation and reconstruction software were developed for the AX-PET demonstrator.

  20. Designing and constructing of a two scintillator crystal rotatable telescope for muon flux variation studies

    NASA Astrophysics Data System (ADS)

    Alghamdi, Abdullrahman; Maghrabi, Abdullrahman H.; Almutari, Mohammed M.

    2014-07-01

    A rotatable muon detection telescope with two layers of scintillators was designed and constructed at the physics detector laboratory at KACST, Saudi Arabia. The objective of this system is to study the zenith angle dependence of high energy cosmic ray muons. The system has the flexibility to rotate in all directions to cover the zenith angle from 0- 900 for muon distribution studies, as well as the azimuth angle from 0-3590 to observe the geomagnetic field effects on it. In this paper, the designing and the construction works as well as the calibration procedures for the detection system will be given. Some of the preliminarily results and some of the future experiments and possible modifications will be outlined.

  1. A comparison of the use of sodium iodide and lanthanum bromide scintillation crystals for airborne surveys

    NASA Astrophysics Data System (ADS)

    Bailey, Derek M.

    The Environmental Protection Agency (EPA) Aerial Spectral Environmental Collection Technology (ASPECT) program performs aerial radiological and chemical characterization of geographical regions of interest. Airborne surveys are performed to characterize environmental radionuclide content, for mineral exploration, as well as for emergency scenarios such as major releases or lost sources. Two radiological detection systems are used by the ASPECT team for gamma-ray detection and characterization: lanthanum bromide [LaBr 3(Ce)] and sodium iodide [NaI(Tl)] scintillation systems. An aerial survey of a uranium mine in the western United States was performed using both NaI(Tl) and LaBr3(Ce) detection systems. Analyses of the survey data were performed with RadAssist software and applying International Atomic Energy Agency (IAEA) airborne gamma ray mapping guidelines. The data for the survey were corrected for cross-over, which is spectral interference from higher energy photons as a result of Compton scattering, height attenuation, cosmic ray contribution to signal, and Radon contribution to signal. Two radiation survey contours were generated from each discrete data set. Based on analysis of the uranium mine survey results, LaBr3(Ce) produced a product comparable to that of NaI(Tl). The LaBr3(Ce) detection system contained 1/16th the scintillating volume and had a total system weight that was 1/4th that of the NaI(Tl) system. LaBr3(Ce) demonstrated a clear advantage over NaI(Tl) detectors in system mobility, and weight factors in airborne gamma ray spectroscopy.

  2. Czochralski growth of Gd3(Al5-xGax)O12 (GAGG) single crystals and their scintillation properties

    NASA Astrophysics Data System (ADS)

    Kurosawa, Shunsuke; Shoji, Yasuhiro; Yokota, Yuui; Kamada, Kei; Chani, Valery I.; Yoshikawa, Akira

    2014-05-01

    Ce:Gd3(AlxGa1-x)5O12 (x=2.5/5 and 3/5, Ce:GAGG-2.5 and Ce:GAGG-3) crystals were grown by the Czochralski process in order to reduce cost of the starting materials as compared with conventional Ce:Gd3Al2Ga3O12 (Ce:GAGG-2) crystal which have high light output. Although perovskite phase was detected in Ce:GAGG-3, Ce:GAGG-2.5 had single-phase garnet structure. Solidification fraction for the Ce:GAGG-2.5 growth was 0.52. Optical properties including transmittance, emission, and excitation spectra of 30 samples cut from the Ce:GAGG-2.5 bulk ingot did not depend on their original position along the growth axis. These samples had light outputs of approximately 58,000±3000 photons/MeV. However, scintillation decay times varied from 140 to 200 ns and depended on the position clearly.

  3. Pulse shape discrimination characteristics of stilbene crystal, pure and 6Li loaded plastic scintillators for a high resolution coded-aperture neutron imager

    NASA Astrophysics Data System (ADS)

    Cieślak, M. J.; Gamage, K. A. A.; Glover, R.

    2017-07-01

    Pulse shape discrimination performances of single stilbene crystal, pure plastic and 6Li loaded plastic scintillators have been compared. Three pulse shape discrimination algorithms have been tested for each scintillator sample, assessing their quality of neutron/gamma separation. Additionally, the digital implementation feasibility of each algorithm in a real-time embedded system was evaluated. Considering the pixelated architecture of the coded-aperture imaging system, a reliable method of simultaneous multi-channel neutron/gamma discrimination was sought, accounting for the short data analysis window available for each individual channel. In this study, each scintillator sample was irradiated with a 252Cf neutron source and a bespoke digitiser system was used to collect the data allowing detailed offline examination of the sampled pulses. The figure-of-merit was utilised to compare the discrimination quality of the collected events with respect to various discrimination algorithms. Single stilbene crystal presents superior neutron/gamma separation performance when compared to the plastic scintillator samples.

  4. Effect of Mg co-doping on scintillation properties of Ce:Gd3(Ga, Al)5O12 single crystals with various Ga/Al ratios

    NASA Astrophysics Data System (ADS)

    Yoshino, Masao; Kamada, Kei; Shoji, Yasuhiro; Yamaji, Akihiro; Kurosawa, Shunsuke; Yokota, Yuui; Ohashi, Yuji; Yoshikawa, Akira; Chani, Valery I.

    2017-06-01

    Mg co-doped Ce1%:Gd3GaxAl5-xO12 (Ce:GAGG) crystals (x=2.4, 2.7, 3.0) were successfully grown by the Czochralski (Cz) method. Effect of Mg co-doping on the scintillation properties of Ce:GAGG was examined. This study covers measurements of solidification fraction and scintillation properties such as light yield, energy resolution and non-proportionality for each crystal. Pulse-height spectra of various gamma and X-ray sources with energies ranged from 30 keV to 662 keV were measured. Regardless of the presence/absence of Mg dopant, the non-proportionality curves with lower content of gallium in the crystal structure tend to improve. Mg co-doped Ce:GAGG samples did not show a significant difference as compared with non co-doped Ce:GAGG. Mg co-doped crystals with x=2.4 and 2.7 showed the promising scintillation properties of faster decay time and higher energy resolution than those with x=3.0.

  5. Radiation damage effects in Y2SiO5:Ce scintillation crystals under γ-quanta and 24 GeV protons

    NASA Astrophysics Data System (ADS)

    Auffray, E.; Borisevitch, A.; Gektin, A.; Gerasymov, Ia.; Korjik, M.; Kozlov, D.; Kurtsev, D.; Mechinsky, V.; Sidletskiy, O.; Zoueyski, R.

    2015-05-01

    This work focuses on the study of changes in the optical transmission of Y2SiO5:Ce crystals caused by ionizing radiation from γ-quanta and high energy protons. Radioisotope content of proton-irradiated crystals, transmission and induced absorption spectra, and scintillation characteristics are measured after irradiation with protons. In contrast to crystals of heavy complex oxides, Y2SiO5:Ce crystals do not demonstrate significant deterioration of transmission in the luminescence range (400-600 nm) under irradiation. Such crystals can be considered as a material for construction of detecting cells of the calorimetric detectors at LHC with high luminosity. The feasibility of growing large crackless Y2SiO5:Ce crystals with a diameter up to 50 mm and length up to 250 mm is demonstrated.

  6. SCINTILLATION EXPOSURE RATE DETECTOR

    DOEpatents

    Spears, W.G.

    1960-11-01

    A radiation detector for gamma and x rays is described. The detector comprises a scintillation crystal disposed between a tantalum shield and the input of a photomultiplier tube, the crystal and the shield cooperating so that their combined response to a given quantity of radiation at various energy levels is substantially constant.

  7. A deeper insight into (Lu,Y)AG:Pr scintillator crystals

    NASA Astrophysics Data System (ADS)

    Drozdowski, W.; Wojtowicz, A. J.; Brylew, K.; Łachmański, W.; Talik, E.; Szubka, M.; Kusz, J.; Guzik, A.; Balin, K.; Kisielewski, J.; Świrkowicz, M.; Pajączkowska, A.

    2017-02-01

    Interior of Czochralski-grown (Lu,Y)AG:Pr crystals has been examined by means of several techniques, such as X-Ray Photoelectron Spectroscopy, X-Ray Diffraction, Time-of-Flight Secondary Ion Mass Spectrometry, and magnetic susceptibility measurements. Additionally, their luminescence has been monitored at various combinations of a double-beam (X-ray/IR) excitation.

  8. The growth of deactivated layers on CsI(Na) scintillating crystals

    NASA Technical Reports Server (NTRS)

    Goodman, N. B.

    1975-01-01

    An effective and sensitive measurement of the depth of a deactivated or dead layer can be obtained from the relative attenuation of the 22.162 KeV and 87.9 KeV X-rays emitted by Cd 109. The alpha-particles emitted by Am 241 are also useful in measuring dead layers less than 25 microns. The properties and temporal development of dead layers are discussed in detail. The rate of growth of a deal layer is closely related to the ambient humidity, and the damage to the crystal is irreversible by any known process. The dead layer can be minimized by polishing all crystal surfaces and by keeping the crystal in a vacuum or a dry atmosphere. Since a dead layer seriously inhibits the response of a crystal to X-rays of energies below approximately 20 keV, CsI(Na) detectors should not be used at these energies unless precautions are taken to ensure that no dead layer forms.

  9. Crystal structure and thermal expansion of a CsCe2Cl7 scintillator

    DOE PAGES

    Zhuravleva, M.; Lindsey, A.; Chakoumakos, B. C.; ...

    2015-04-06

    Here we used single-crystal X-ray diffraction data to determine crystal structure of CsCe2Cl7. It crystallizes in a P1121/b space group with a = 19.352(1) Å, b = 19.352(1) Å, c = 14.838(1) Å, γ = 119.87(2) ° , and V = 4818.6(5) Å3. Differential scanning calorimetry measurements combined with the structural evolution of CsCe2Cl7 via X-ray diffractometry over a temperature range from room temperature to the melting point indicates no obvious intermediate solid-solid phase transitions. The anisotropy in the average linear coefficient of thermal expansion of the a axis (21.3 10-6/ °C) with respect to the b and c axesmore » (27.0 10-6/ °C) was determined through lattice parameter refinement of the temperature dependent diffraction patterns. Lastly, these findings suggest that the reported cracking behavior during melt growth of CsCe2Cl7 bulk crystals using conventional Bridgman and Czochralski techniques may be largely attributed to the anisotropy in thermal expansion.« less

  10. Electron spin resonance study of self-trapped holes in CdWO{sub 4} scintillator crystals

    SciTech Connect

    Laguta, V. V.; Nikl, M.; Rosa, J.; Grinyov, B. V.; Nagornaya, L. L.; Tupitsina, I. A.

    2008-11-15

    The self-trapping of holes at oxygen anions was studied by electron spin resonance in UV irradiated CdWO{sub 4} crystals. Analysis of superhyperfine interaction of the holes with {sup 183}W and {sup 111,113}Cd isotopes shows that the self-trapped hole is either delocalized in the space between two energetically equivalent nearest neighbor oxygen ions or tunnels between them. When the temperature increases above 40-50 K the self-trapped holes are thermally liberated and can be retrapped by oxygen ions perturbed by impurity ions. In case of the Nb{sup 5+} or Li{sup +} stabilizing impurities the O{sup -} centers are thermally stable up to 160-170 K. The study of kinetic characteristics of the self-trapped holes suggests that holes leave oxygen ions by thermally assisted tunneling mechanism via two slightly different channels. Corresponding ionization probabilities are defined by the Arrhenius law with an average thermal ionization energy E=90(5) meV. Calculated pre-exponential factors, about 10{sup 5} s{sup -1}, are small, which is consistent with the tunneling mechanism. Thermal stability and kinetic characteristics of the trapped holes are discussed in light of the scintillation and thermoluminescence characteristics of CdWO{sub 4}.

  11. Search for double beta decay of 116Cd with enriched 116CdWO4 crystal scintillators (Aurora experiment)

    NASA Astrophysics Data System (ADS)

    Danevich, F. A.; Barabash, A. S.; Belli, P.; Bernabei, R.; Cappella, F.; Caracciolo, V.; Cerulli, R.; Chernyak, D. M.; d'Angelo, S.; Incicchitti, A.; Kobychev, V. V.; Konovalov, S. I.; Laubenstein, M.; Mokina, V. M.; Poda, D. V.; Polischuk, O. G.; Shlegel, V. N.; Tretyak, V. I.; Umatov, V. I.

    2016-05-01

    The Aurora experiment to investigate double beta decay of 116 Cd with the help of 1.162 kg cadmium tungstate crystal scintillators enriched in 116 Cd to 82% is in progress at the Gran Sasso Underground Laboratory. The half-life of 116 Cd relatively to the two neutrino double beta decay is measured with the highest up-to-date accuracy T1/2 = (2.62 ± 0.14) × 1019 yr. The sensitivity of the experiment to the neutrinoless double beta decay of 116 Cd to the ground state of 116 Sn is estimated as T1/2 ≥ 1.9 × 1023 yr at 90% CL, which corresponds to the effective Majorana neutrino mass limit (mv) ≤ (1.2 — 1.8) eV. New limits are obtained for the double beta decay of 116 Cd to the excited levels of 116 Sn, and for the neutrinoless double beta decay with emission of majorons.

  12. Development of radiopure cadmium tungstate crystal scintillators from enriched {sup 106}Cd and {sup 116}Cd to search for double beta decay

    SciTech Connect

    Danevich, F. A.; Boiko, R. S.; Chernyak, D. M.; Kobychev, V. V.; Kropivyansky, B. N.; Mokina, V. M.; Nikolaiko, A. S.; Poda, D. V.; Podviyanuk, R. B.; Tretyak, V. I.; Barabash, A. S.; Konovalov, S. I.; Umatov, V. I.; Belli, P.; Bernabei, R.; D'Angelo, S.; Brudanin, V. B.; Cappella, F.; Incicchitti, A.; Caracciolo, V.; and others

    2013-08-08

    Cadmium tungstate crystal scintillators enriched in {sup 106}Cd up to 66% ({sup 106}CdWO{sub 4}) and in {sup 116}Cd up to 82% ({sup 116}CdWO{sub 4}) have been developed. The low radioactive contamination of the crystals measured on the level of ≤ 1.5 mBq/kg ({sup 40}K), ≤ 0.005 - 0.012 mBq/kg ({sup 226}Ra), 0.04 - 0.07 mBq/kg ({sup 228}Th) allows to carry out high sensitivity experiments to search for double beta processes in {sup 106}Cd and {sup 116}Cd.

  13. Exploratory growth in the Li2MoO4-MoO3 system for the next crystal generation of heat-scintillation cryogenic bolometers

    NASA Astrophysics Data System (ADS)

    Velázquez, Matias; Veber, Philippe; Moutatouia, Meryem; de Marcillac, Pierre; Giuliani, Andrea; Loaiza, Pia; Denux, Dominique; Decourt, Rodolphe; El Hafid, Hassan; Laubenstein, Matthias; Marnieros, Stefanos; Nones, Claudia; Novati, Valentina; Olivieri, Emiliano; Poda, Denys V.; Zolotarova, Anastasiia S.

    2017-03-01

    In this work, we report on the Czochralski growth of Li2MoO4 crystals up to 230 g for heat-scintillation cryogenic bolometers likely to be used in astroparticle physics and neutron spectroscopy. Their transmission properties, radiopurity levels and detector behavior characterizations were carried out in order to validate the crystal growth process. The melting characteristics, the partition coefficients of a broad range of impurities, the thermal expansion (lattice parameters and dilatometry) and specific heat properties of the crystals were measured, over a broad temperature range for the last two, providing new data likely to be used in crystal growth process numerical simulations. We also investigated the crystal growth of Li4Mo5O17 and determined its melting behavior and specific heat. The physical properties directly relevant to heat-scintillation cryogenic bolometers of Li2MoO4 and Li4Mo5O17 are discussed in the context of the current materials developed for such applications.

  14. Bridgman crystal growth and spectral properties of Er doped PbWO4 as stimulated Raman crystals

    NASA Astrophysics Data System (ADS)

    Xiong, Wei; Chen, Liang; Guo, Feiyun; Zhou, Yao; Su, Liangbi; Yang, Yan; Yuan, Hui

    2012-06-01

    Several Er doped (0.2 at%, 0.5 at%, and 1.0 at%) PbWO4 single crystals were grown by Bridgman method with the size of Φ20 × 100 mm. The absorption spectra of Er:PWO samples were measured to investigate the spectral properties of Er3+ ions according to Judd-Ofelt theory. The phenomenological intensity parameters Ωλ were fitted to calculate the spectral parameters of several radiative transitions of Er3+ ions, and the possibility of 4I13/2 → 4I15/2 transition at about 1.5 μm of Er3+ ions in PWO crystal was also discussed. The energy transfer from PWO matrix to Er3+ ions was investigated based on the photoluminescence spectra, and the frequency shifting effect of Er3+ ions on PWO crystal was discussed according to the spontaneous Raman spectra. The 1.5 μm fluorescence spectra of different Er:PWO samples were measured under the excitation at 980 nm.

  15. Hole capture in PbWO{sub 4}:Mo,La(Y) scintillator crystals

    SciTech Connect

    Laguta, V. V.; Buryi, M.; Nikl, M.; Rosa, J.; Zazubovich, S.

    2011-03-01

    The processes of hole localization in PbWO{sub 4}:Mo,La(Y) single crystals were investigated by electron spin resonance. It was found that the holes created by uv irradiation are trapped at the regular oxygen ions in the vicinity of perturbing defects such as lead vacancies, impurity ions (La,Y), and other lattice imperfections. This leads to a variety of O{sup -} centers which differ in both the thermal stability (from about 160 K up to 240 K) and spectroscopic parameters. The thermal release of such trapped holes and their subsequent recombination with electrons stored at different traps, including (MoO{sub 4}){sup 3-} complexes, are accompanied by the appearance of the thermally stimulated luminescence peaks located at around 190 K and in the 225-250 K range.

  16. A novel scintillation imager with charge-spread discrimination. Analytical models suitable for crystal-arrays

    NASA Astrophysics Data System (ADS)

    Scafè, Raffaele; Pellegrini, Rosanna; Cinti, Maria N.; Puccini, Marco; Pani, Roberto

    2016-10-01

    Present paper describes a method for obtaining the physical quantities characterizing single-events based on fitting experimental 2-D charge-profiles to two analytical models. First results are presented regarding a 10×10 LuYAP:Ce array of 2×2×10 mm3 crystal pixels coupled to a H10966 Hamamatsu 8×8 multi-anode assembly under radio-isotopic irradiations and from self-activity. Results show that a photo multiplier tube with cross plate anode configuration would be preferable than a multi anode one due to uniformity, cost, and connections constraints. Among the results a plot of charge spread Vs. charge is to be cited because it was not yet published in scientific literature.

  17. Enhanced light extraction of LYSO scintillator by photonic crystal structures from a modified porous anodized aluminum oxide layer

    NASA Astrophysics Data System (ADS)

    Zhang, Juannan; Liu, Bo; Zhu, Zhichao; Wu, Qiang; Cheng, Chuanwei; Liu, Jinliang; Chen, Liang; Ouyang, Xiaoping; Gu, Mu; Xu, Jun; Chen, Hong

    2017-08-01

    Although porous anodized aluminum oxide layer can be used to extract scintillation light from a LYSO scintillator, the low refractive index contrast of porous AAO layer obtains a moderate enhancement. In this investigation, we have designed and fabricated a modified porous anodized aluminum oxide layer with conformal deposition layer of high refractive index material of TiO2 on the surface of LYSO scintillator, achieving a significant enhancement by 60% with wavelength- and angle-integrated emission intensity. The fabrication method of the present study is simple and low-cost for the large area applications in the field of radiation detection.

  18. Optical and scintillation properties of ce-doped (Gd2Y1)Ga2.7Al2.3O12 single crystal grown by Czochralski method

    NASA Astrophysics Data System (ADS)

    Wang, Chao; Wu, Yuntao; Ding, Dongzhou; Li, Huanying; Chen, Xiaofeng; Shi, Jian; Ren, Guohao

    2016-06-01

    Multicomponent garnets, due to their excellent light yield and energy resolution, become one of the most promising scintillators used for homeland security and nuclear non-proliferation applications. This work focuses on the optimization of Ce-doped (Gd,Y)3(Ga,Al)5O12 scintillators using a combination strategy of pre-screening and scale-up. Ce-doped GdxY1-xGayAl5-yO12 (x=1, 2 and y=2, 2.2, 2.5, 2.7, 3) polycrystalline powders were prepared by high-temperature solid state reaction method. The desired garnet phase in all the samples was confirmed using X-ray diffraction measurement. By comparing the radioluminescence intensity, the highest scintillation efficiency was achieved at a component of Gd2Y1Ga2.7Al2.3O12:Ce powders. A (Gd2Y1)Ga2.7Al2.3O12 doped with 1% Ce single crystal with dimensions of Ø35×40 mm was grown by Czochralski method using a <111> oriented seed. Luminescence and scintillation properties were measured. An optical transmittance of 84% was achieved in the concerned wavelength from 500 to 800 nm. Its 5d-4f emission of Ce3+ is at 530 nm. The light yield of a Ce1%: Gd2Y1Ga2.7Al2.3O12 single crystal slab at a size of 5×5×1 mm3 can reach about 65,000±3000 Ph/MeV along with two decay components of 94 and 615 ns under 137Cs source irradiation.

  19. Scintillation characteristics of LiCaAlF6-based single crystals under X-ray excitation

    NASA Astrophysics Data System (ADS)

    Nikl, M.; Bruza, P.; Panek, D.; Vrbova, M.; Mihokova, E.; Mares, J. A.; Beitlerova, A.; Kawaguchi, N.; Fukuda, K.; Yoshikawa, A.

    2013-04-01

    LiCaAlF6-based scintillators are studied under X- and soft gamma-ray excitations. Under nanosecond pulsed soft X-ray laser excitation the scintillation decay is measured with extremely high dynamical resolution and broad time scale. The undoped LiCaAlF6 shows complex temperature dependence of exciton luminescence and tunneling-driven energy transfer process in scintillation decay. In both the Ce and Eu-doped LiCaAlF6 the dominant part of measured scintillation decay is due to prompt recombination of electrons and holes at the doped emission centers. Nevertheless, the measured light yield value is considerably lower with respect to the derived upper limits. Possible origin of its deterioration is discussed.

  20. Hole and electron traps in the YAlO{sub 3} single crystal scintillator

    SciTech Connect

    Laguta, V. V.; Nikl, M.; Rosa, J.; Vedda, A.; Mihokova, E.; Blazek, K.

    2009-07-15

    The processes of hole and electron localization in YAlO{sub 3} single crystals were investigated by electron-spin resonance. It was found that holes created by UV or x-ray irradiation are trapped at regular oxygen ions forming two types of O{sup -} hole centers corresponding to hole localization at two inequivalent oxygen ions which are located in Y and Al planes, respectively. The hole can be either autolocalized or additionally stabilized by a defect in the neighborhood of the oxygen ion such as yttrium vacancy or an impurity ion at Y site. This leads to a variety of O{sup -} centers which differ both by thermal stability (from about 14 K up to room temperature) and spectral parameters. Electron-type trapping sites are assigned to Y{sub Al} antisite ions. After trapping an electron they become paramagnetic Y{sub Al}{sup 2+} centers. They are found in several configurations with thermal stability up to above 300 K that enables the radiative recombination of freed holes with such localized electrons and the appearance of thermoluminescence peaks. It is shown that the electron trapped around Y{sub Al} antisite ion is additionally stabilized either by an oxygen vacancy or by a defect at Y site. The yttrium antisite ions in the lattice were directly identified by {sup 89}Y nuclear magnetic resonance.

  1. Study of a Li doped CsI scintillator crystal as a neutron detector

    NASA Astrophysics Data System (ADS)

    Madi Filho, T.; Pereira, M. C. C.; Berretta, J. R.; Cárdenas, J. P. N.

    2015-07-01

    The radiation monitoring system is an important requirement in the premises of a nuclear reactor. A variety of types of radiation (neutrons. gamma. beta and fission products) exist in a reactor. associated to the broad energy spectrum of these radiations. implying the need of detectors to be used in the reactor system and security. as well as radiation monitoring. As the neutron sources are associated to gamma radiation. it is necessary that the neutron detecting system may be capable to discriminate the gamma interference. In our work environment. there are two Nuclear Research Reactors and a neutron irradiator with two AmBe sources (592GBq of Am. each). These conditions warrant the development of new types of detectors. Due to the absence of charge in the neutron. it is necessary to use a converter material that generates radiations capable to produce signals in the detector. Materials with high cross section. like Li or B. are used for this purpose. The CsIcrystal doped with 6Li has been studied. The concentration of the lithium doping element (Li) studied was 10-3M. The detector test was done using an AmBe source (37GBq) and gamma sources. The crystal was coupled to a photomultiplier.

  2. Luminescent and scintillation properties of Ce-doped Tb3Al5O12 crystal grown from Al-rich composition

    NASA Astrophysics Data System (ADS)

    Nakauchi, Daisuke; Okada, Go; Kawano, Naoki; Kawaguchi, Noriaki; Yanagida, Takayuki

    2017-07-01

    A Ce-doped Tb3Al5O12 single crystal was successfully synthesized via the floating zone method in an Al-rich composition. In both photoluminescence and scintillation, the emissions were predominantly due to the 5d-4f transitions of Ce3+ peaking around 550 nm, but emissions due to defects and the 4f-4f transitions of Tb3+ were revealed by the time-resolved analyses. The crystal quality and luminescence intensity were sufficiently high such that the crystal was applicable for pulse-height spectrum measurement. Under 137Cs γ-ray exposure, a clear photoabsorption peak was observed, and the estimated light yield was 57,000 photons/MeV.

  3. Test beam results with a sampling calorimeter of cerium fluoride scintillating crystals and tungsten absorber plates for calorimetry at the HL-LHC

    NASA Astrophysics Data System (ADS)

    Becker, R.; Dissertori, G.; Djambazov, L.; Donegà, M.; Dröge, M.; Haller, C.; Horisberger, U.; Lustermann, W.; Nessi-Tedaldi, F.; Quittnat, M.; Pandolfi, F.; Peruzzi, M.; Schönenberger, M.; Cavallari, F.; Dafinei, I.; Diemoz, M.; D`Imperio, G.; del Re, D.; Gelli, S.; Jorda Lope, C.; Meridiani, P.; Micheli, F.; Nuccetelli, M.; Organtini, G.; Paramatti, R.; Pellegrino, F.; Rahatlou, S.; Rovelli, C.; Santanastasio, F.; Soffi, L.; Tabarelli de Fatis, T.; Martelli, A.; Monti, V.; Pastrone, N.; Trapani, P. P.; Candelise, V.; Della Ricca, G.

    2016-07-01

    A sampling calorimeter using cerium fluoride scintillating crystals as active material, interleaved with absorber plates made of tungsten, and read out by wavelength-shifting fibres has been tested with high-energy electron beams at the CERN SPS H4 beam line, as well as with lower-energy beams at the INFN Frascati Beam Test Facility in Italy. Energy resolution studies revealed a low stochastic term (< 10 % /√{ E }). This result, combined with high radiation hardness of the material used, marks this sampling calorimeter as a good candidate for the detectors' forward regions during the high luminosity phase of LHC.

  4. Control of mean ionic radius at Ca site by Sr co-doping for Ce doped LiCaAlF6 single crystals and the effects on optical and scintillation properties

    NASA Astrophysics Data System (ADS)

    Yokota, Yuui; Yamaji, Akihiro; Kurosawa, Shunsuke; Kamada, Kei; Yoshikawa, Akira

    2014-10-01

    Sr co-doped Ce:LiCaAlF6 [Ce:Li(Ca,Sr)AlF6] crystals with various Ca/Sr ratios were grown by a micro-pulling-down (μ-PD) method and effects of Sr co-doping on crystal structure, chemical composition, optical and scintillation properties for Ce:LiCaAlF6 crystals were investigated as a neutron scintillator. High transparent Ce2%:Li(Ca,Sr)AlF6 crystals with 2% and 5% Sr contents were obtained while Ce2%:Li(Ca,Sr)AlF6 crystals with 10% and 20% Sr contents included milky parts in the crystals. a- and c-axis lengths of Ce:Li(Ca,Sr)AlF6 phase systematically increased with an increase of Sr content. In addition to the emission at 284 and 308 nm from Ce3+ ion, emission peaks at 367 nm appeared by Sr co-doping.

  5. Effect of ZnI2 cosolute on quality and performance of γ-CuI ultrafast scintillation crystal grown via evaporation method in acetonitrile solvent

    NASA Astrophysics Data System (ADS)

    Yue, Shuangqiang; Gu, Mu; Liu, Xiaolin; Zhang, Juannan; Huang, Shiming; Liu, Bo; Ni, Chen

    2017-04-01

    γ-CuI single crystal was grown via evaporation method in ZnI2 acetonitrile solvent. The ZnI2 plays a unique role which can not only increase the solubility of CuI in acetonitrile but also introduce the Zn and I ions in the crystal. The γ-CuI crystal grown in ZnI2 acetonitrile is regular and transparent. Its size reaches up to 18 × 11 × 2 mm3 which is larger than that of the crystal grown in pure acetonitrile. In terms of the photoluminescence, the intensity of the emission at 411 nm of the crystal grown with ZnI2 as a cosolute is much higher than that of the crystal grown without ZnI2, which implies that the crystallinity of the crystal can be improved by ZnI2 doping. The X-ray excited luminescence of the crystal shows that the emission at 435 nm can be significantly enhanced and the emission near 680 nm can be suppressed by introducing Zn and I in the natural non-stoichiometry γ-CuI crystal. The nature of the phenomena is discussed. The decay time of the emission at 435 nm similar to that of the emission at 411 nm is faster than the detection limit of the instrument, i.e. less than 1 ns, and the average decay time of the emission near 680 nm is about 183 ns. The results can provide a useful guide to optimize the scintillation properties of γ-CuI single crystal.

  6. Scintillator material

    DOEpatents

    Anderson, David F.; Kross, Brian J.

    1992-01-01

    An improved scintillator material comprising cerium fluoride is disclosed. Cerium fluoride has been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to known scintillator materials such as thallium-doped sodium iodide, barium fluoride and bismuth germanate. As a result, cerium fluoride is favorably suited for use as a scintillator material in positron emission tomography.

  7. Scintillator material

    DOEpatents

    Anderson, David F.; Kross, Brian J.

    1994-01-01

    An improved scintillator material comprising cerium fluoride is disclosed. Cerium fluoride has been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to known scintillator materials such as thallium-doped sodium iodide, barium fluoride and bismuth germanate. As a result, cerium fluoride is favorably suited for use as a scintillator material in positron emission tomography.

  8. Scintillator material

    DOEpatents

    Anderson, D.F.; Kross, B.J.

    1992-07-28

    An improved scintillator material comprising cerium fluoride is disclosed. Cerium fluoride has been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to known scintillator materials such as thallium-doped sodium iodide, barium fluoride and bismuth germanate. As a result, cerium fluoride is favorably suited for use as a scintillator material in positron emission tomography. 4 figs.

  9. Scintillator material

    DOEpatents

    Anderson, D.F.; Kross, B.J.

    1994-06-07

    An improved scintillator material comprising cerium fluoride is disclosed. Cerium fluoride has been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to known scintillator materials such as thallium-doped sodium iodide, barium fluoride and bismuth germanate. As a result, cerium fluoride is favorably suited for use as a scintillator material in positron emission tomography. 4 figs.

  10. Development of new scintillators for medical applications

    NASA Astrophysics Data System (ADS)

    Lecoq, Paul

    2016-02-01

    For a long time the discovery of new scintillators has been more serendipitous than driven by a deep understanding of the mechanisms at the origin of the scintillation process. This situation has dramatically changed since the 1990's with an increased demand for scintillators of better performance for large particle physics experiments as well as for medical imaging. It is now possible to design a scintillator for a specific purpose. The bandgap can be adjusted, the traps energy levels and their concentration can be finely tuned and their influence can be damped or on the contrary enhanced by specific doping for an optimization of the performance of the scintillator. Several examples are given in this paper of such crystal engineering attempts to improve the performance of crystal scintillators used in medical imaging devices. An attention is also given to spectacular progress in crystal production technologies, which open new perspectives for large scale and cost effective crystal production with consistent quality.

  11. Photofraction of a 5 cm x 2 cm BGO scintillator. [bismuth germanate crystal for use in cosmic gamma ray detector

    NASA Technical Reports Server (NTRS)

    Dunphy, P. P.; Forrest, D. J.

    1985-01-01

    The photofraction of a 5.1 cm x 2.0 cm bismuth germanate (BGO) scintillator was measured over a gamma-ray energy range of 0.2 to 6.1 MeV. Several methods, used to minimize the effect of room scattering on the measurement, are discussed. These include a gamma-gamma coincidence technique, a beta-gamma coincidence technique, and the use of sources calibrated with a standard 7.6 cm x 7.6 cm sodium iodide scintillator.

  12. Investigation of high resolution compact gamma camera module based on a continuous scintillation crystal using a novel charge division readout method

    NASA Astrophysics Data System (ADS)

    Dai, Qiu-Sheng; Zhao, Cui-Lan; Zhang, Hua-Lin; Qi, Yu-Jin

    2010-08-01

    The objective of this study is to investigate a high performance and lower cost compact gamma camera module for a multi-head small animal SPECT system. A compact camera module was developed using a thin Lutetium Oxyorthosilicate (LSO) scintillation crystal slice coupled to a Hamamatsu H8500 position sensitive photomultiplier tube (PSPMT). A two-stage charge division readout board based on a novel sub-tractive resistive readout with a truncated center-of-gravity (TCOG) positioning method was developed for the camera. The performance of the camera was evaluated using a flood 99mTc source with a four-quadrant bar-mask phantom. The preliminary experimental results show that the image shrinkage problem associated with the conventional resistive readout can be effectively overcome by the novel subtractive resistive readout with an appropriate fraction subtraction factor. The response output area (ROA) of the camera shown in the flood image was improved up to 34%, and an intrinsic spatial resolution better than 2 mm of detector was achieved. In conclusion, the utilization of a continuous scintillation crystal and a flat-panel PSPMT equipped with a novel subtractive resistive readout is a feasible approach for developing a high performance and lower cost compact gamma camera.

  13. Cosmic ray effect on the X-ray Trigger Telescope of UFFO/Lomonosov using YSO scintillation crystal array in space

    NASA Astrophysics Data System (ADS)

    Kim, M. B.; Jeong, S.; Jeong, H. M.; Leonov, V.; Lee, J.; Park, I. H.; Amelushkin, A. M.; Barinova, V. O.; Bogomolov, A. V.; Bogomolov, V. V.; Brandt, S.; Budtz-Jørgensen, C.; Castro-Tirado, A. J.; Chen, P.; Connell, P.; Garipov, G.; Gorbovskoy, E. S.; Dzhioeva, N. L.; Eyles, C.; Huang, M. H. A.; Iyudin, A. F.; Kalegaev, V. V.; Kasarjan, P. S.; Kim, J. E.; Kornilov, V. G.; Kuznetsova, E. A.; Lim, H.; Lipunov, V. M.; Liu, T. C.; Myagkova, I. N.; Nam, J. W.; Panasyuk, M. I.; Panchenko, M. I.; Petrov, V. L.; Prokhorov, A. V.; Reglero, V.; Ripa, J.; Rodrigo, J. M.; Shustova, A. N.; Svertilov, S. I.; Tyurina, N. V.; Yashin, I. V.

    2017-08-01

    UFFO Burst Alert and Trigger telescope (UBAT) is the X-ray trigger telescope of UFFO/Lomonosov to localize X-ray source with coded mask method and X-ray detector. Its Xray detector is made up of 36 8×8 pixels Yttrium OxyorthoSilicate (Y2SiO5:Ce, YSO) scintillation crystal arrays and 36 64-channel Multi-Anode PhotoMultiplier Tubes (MAPMTs) for space mission. Its effective detection area is 161cm^2 and energy range is several keV to 150 keV. It was successfully launched in April 28, 2016. In several calibration run, we got several X-ray background data. We already knew X-ray background flux is 2-3 counts/cm^2/sec in space.However our X-ray background data shows approximately 7-8 times higher than what we know. There are many candidates to explain high X-ray background count in space. One of candidates is cosmic ray. We will report cosmic ray effect on the X-ray detector using YSO scintillation crystal arrays in space.

  14. Use of digirad 2020tc Imager, a multi-crystal scintillation camera with solid-state detectors in one case for the imaging of autografts of parathyroid glands.

    PubMed

    Fukumitsu, N; Tsuchida, D; Ogi, S; Uchiyama, M; Mori, Y; Ooshita, T; Narrita, H; Yamamoto, H; Takeyama, H

    2001-12-01

    99mTc-methoxy-isobutyl-isonitrile (99mTc-MIBI) scintigraphy with Digirad 2020tc ImagerTM (2020tc), which was a multi-crystal scintillation camera with solid-state detectors was performed for patients with secondary hyperparathyroidism having autografts of parathyroid glands in the right arm. With the 2020tc camera, three abnormal accumulations were found in the right arm. The images obtained with this camera were superior in resolution to those obtained with a conventional NaI crystal gamma camera (ZLC7500, Siemens, Germany). The next day, resection of autografts of parathyroid glands was done. Four hyperplastic parathyroid glands were resected and all were hyperplastic in pathological findings.

  15. Luminescence of CaWO4, CaMoO4, and ZnWO4 scintillating crystals under different excitations

    NASA Astrophysics Data System (ADS)

    Mikhailik, V. B.; Kraus, H.; Miller, G.; Mykhaylyk, M. S.; Wahl, D.

    2005-04-01

    The luminescence spectra of CaWO4, CaMoO4, and ZnWO4 scintillating crystals were investigated in the temperature range 8-400K. The excitation photon energy was varied from the ultraviolet (4.5eV ) to the hard x-ray region (35keV). It is found that as the excitation energy decreases the relative intensity of the low-energy luminescence band, attributed to the extrinsic emission of defect centers in CaWO4 and CaMoO4 crystals, increases. This observation is interpreted in terms of the total absorption of incident radiation, i.e., the variation of the mean penetration depth of the photons with their energy. It indicates that the centers responsible for the extrinsic emission in the crystals with scheelite structure are mainly localized in a thin (˜100nm ) surface layer. On the other hand no noticeable changes with the excitation energy were found in the emission spectra of ZnWO4 crystals with wolframite structure. The possible implication of this finding is discussed. The light yield of the crystals is compared at low temperature using monochromatic x-ray excitation and it is shown that ZnWO4 has ˜10% higher light yield than CaWO4, while this parameter has a factor of 4 lower in CaMoO4.

  16. Scintillation Counters

    NASA Astrophysics Data System (ADS)

    Bell, Zane W.

    Scintillators find wide use in radiation detection as the detecting medium for gamma/X-rays, and charged and neutral particles. Since the first notice in 1895 by Roentgen of the production of light by X-rays on a barium platinocyanide screen, and Thomas Edison's work over the following 2 years resulting in the discovery of calcium tungstate as a superior fluoroscopy screen, much research and experimentation have been undertaken to discover and elucidate the properties of new scintillators. Scintillators with high density and high atomic number are prized for the detection of gamma rays above 1 MeV; lower atomic number, lower-density materials find use for detecting beta particles and heavy charged particles; hydrogenous scintillators find use in fast-neutron detection; and boron-, lithium-, and gadolinium-containing scintillators are used for slow-neutron detection. This chapter provides the practitioner with an overview of the general characteristics of scintillators, including the variation of probability of interaction with density and atomic number, the characteristics of the light pulse, a list and characteristics of commonly available scintillators and their approximate cost, and recommendations regarding the choice of material for a few specific applications. This chapter does not pretend to present an exhaustive list of scintillators and applications.

  17. Design and simulation of a novel method for determining depth-of-interaction in a PET scintillation crystal array using a single-ended readout by a multi-anode PMT.

    PubMed

    Ito, Mikiko; Lee, Jae Sung; Park, Min-Jae; Sim, Kwang-Souk; Hong, Seong Jong

    2010-07-07

    PET detectors with depth-of-interaction (DOI) encoding capability allow high spatial resolution and high sensitivity to be achieved simultaneously. To obtain DOI information from a mono-layer array of scintillation crystals using a single-ended readout, the authors devised a method based on light spreading within a crystal array and performed Monte Carlo simulations with individual scintillation photon tracking to prove the concept. A scintillation crystal array model was constructed using a grid method. Conventional grids are constructed using comb-shaped reflector strips with rectangular teeth to isolate scintillation crystals optically. However, the authors propose the use of triangularly shaped teeth, such that scintillation photons spread only in the x-direction in the upper halves of crystals and in the y-direction in lower halves. DOI positions can be estimated by considering the extent of two-dimensional light dispersion, which can be determined from the multiple anode outputs of a position-sensitive PMT placed under the crystal array. In the main simulation, a crystal block consisting of a 29x29 array of 1.5 mmx1.5 mmx20 mm crystals and a multi-anode PMT with 16x16 pixels were used. The effects of crystal size and non-uniform PMT output gain were also explored by simulation. The DOI resolution estimated for 1.5x1.5x20 mm3 crystals was 2.16 mm on average. Although the flood map was depth dependent, each crystal was well identified at all depths when a corner of the crystal array was irradiated with 511 keV gamma rays (peak-to-valley ratio approximately 9:1). DOI resolution was better than 3 mm up to a crystal length of 28 mm with a 1.5x1.5 mm2 or 2.0x2.0 mm2 crystal surface area. The devised light-sharing method allowed excellent DOI resolutions to be obtained without the use of dual-ended readout or multiple crystal arrays.

  18. Design and simulation of a novel method for determining depth-of-interaction in a PET scintillation crystal array using a single-ended readout by a multi-anode PMT

    NASA Astrophysics Data System (ADS)

    Ito, Mikiko; Lee, Jae Sung; Park, Min-Jae; Sim, Kwang-Souk; Jong Hong, Seong

    2010-07-01

    PET detectors with depth-of-interaction (DOI) encoding capability allow high spatial resolution and high sensitivity to be achieved simultaneously. To obtain DOI information from a mono-layer array of scintillation crystals using a single-ended readout, the authors devised a method based on light spreading within a crystal array and performed Monte Carlo simulations with individual scintillation photon tracking to prove the concept. A scintillation crystal array model was constructed using a grid method. Conventional grids are constructed using comb-shaped reflector strips with rectangular teeth to isolate scintillation crystals optically. However, the authors propose the use of triangularly shaped teeth, such that scintillation photons spread only in the x-direction in the upper halves of crystals and in the y-direction in lower halves. DOI positions can be estimated by considering the extent of two-dimensional light dispersion, which can be determined from the multiple anode outputs of a position-sensitive PMT placed under the crystal array. In the main simulation, a crystal block consisting of a 29 × 29 array of 1.5 mm × 1.5 mm × 20 mm crystals and a multi-anode PMT with 16 × 16 pixels were used. The effects of crystal size and non-uniform PMT output gain were also explored by simulation. The DOI resolution estimated for 1.5 × 1.5 × 20 mm3 crystals was 2.16 mm on average. Although the flood map was depth dependent, each crystal was well identified at all depths when a corner of the crystal array was irradiated with 511 keV gamma rays (peak-to-valley ratio ~9:1). DOI resolution was better than 3 mm up to a crystal length of 28 mm with a 1.5 × 1.5 mm2 or 2.0 × 2.0 mm2 crystal surface area. The devised light-sharing method allowed excellent DOI resolutions to be obtained without the use of dual-ended readout or multiple crystal arrays.

  19. Optical and scintillation properties of Ce:(Gd8AE2)(SiO4)6O2 (AE = Mg, Ca, Sr and Ba) crystals

    NASA Astrophysics Data System (ADS)

    Igashira, Takuya; Mori, Masaki; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

    2017-02-01

    1% Ce-doped and non-doped (Gd8AE2)(SiO4)6O2 (AE = Mg, Ca, Sr and Ba) (denoted as GMS, GCS, GSrS and GBS, respectively) single crystals were grown by the Floating Zone (FZ) method to evaluate their optical and scintillation properties. The Ce:GCS and Ce:GSrS samples exhibited scintillation and photoluminescence (PL) around 400 nm due to the 5d-4f transitions of Ce3+. On the other hand, Ce:GMS and Ce:GBS showed much weaker emissions in the wavelength range of 500-650 nm, in which the origin was associated with the host matrices. The PL decay curves were approximated by a double exponential decay function for all the Ce-doped samples. The decay times ranged around 10-30 and 40-90 ns, and faster components coincided with those of the non-doped samples. The scintillation decay curves of Ce-doped samples, on the other hand, were approximated by single exponential functions with slower decay constants than those of PL decay. These constants were very similar to those of non-doped samples. In the X-ray induced afterglow measurements, Ce:GCS exhibited the lowest afterglow level. The pulse height spectrum of these samples showed a full-energy peak under 241Am 5.5 MeV α-ray irradiation. Among these samples, Ce:GSrS exhibited the highest light yield which was around 600 ph/5.5 MeV-α.

  20. Optical and scintillation characteristics of Gd2YAl2Ga3O12:Ce and Lu2YAl2Ga3O12:Ce single crystals

    NASA Astrophysics Data System (ADS)

    Chewpraditkul, Warut; Sakthong, Ongsa; Pattanaboonmee, Nakarin; Chewpraditkul, Weerapong; Szczesniak, Tomasz; Swiderski, Lukasz; Moszynski, Marek; Kamada, Kei; Yoshikawa, Akira; Nikl, Martin

    2017-06-01

    The optical and scintillation characteristics of Gd2YAl2Ga3O12:Ce and Lu2YAl2Ga3O12:Ce single crystals are investigated. At 662 keV γ-rays, light yield (LY) of 37,900 ph/MeV and energy resolution of 7.0% obtained for Gd2YAl2Ga3O12:Ce are superior to those of 18,900 ph/MeV and 11.5% obtained for Lu2YAl2Ga3O12:Ce. Scintillation decays are measured using the time-correlated single photon counting technique. A fast component decay time of 45 ns with relative intensity of 88% obtained for Lu2YAl2Ga3O12:Ce is superior to that of 50 ns (65%) for Gd2YAl2Ga3O12:Ce. The linear attenuation coefficient at 662 keV γ-rays is also determined and discussed.

  1. Divalent fluoride doped cerium fluoride scintillator

    DOEpatents

    Anderson, David F.; Sparrow, Robert W.

    1991-01-01

    The use of divalent fluoride dopants in scintillator materials comprising cerium fluoride is disclosed. The preferred divalent fluoride dopants are calcium fluoride, strontium fluoride, and barium fluoride. The preferred amount of divalent fluoride dopant is less than about two percent by weight of the total scintillator. Cerium fluoride scintillator crystals grown with the addition of a divalent fluoride have exhibited better transmissions and higher light outputs than crystals grown without the addition of such dopants. These scintillators are useful in radiation detection and monitoring applications, and are particularly well suited for high-rate applications such as positron emission tomography (PET).

  2. Crystal structure, electronic structure, temperature-dependent optical and scintillation properties of CsCe2Br7

    SciTech Connect

    Wu, Yuntao; Shi, Hongliang; Chakoumakos, Bryan C.; Zhuravleva, Mariya; Du, Mao-Hua; Melcher, Charles L.

    2015-10-05

    CsCe2Br7 is a self-activated inorganic scintillator that shows promising performance, but the understanding of the important structure-property relationships is lacking. In this work, we conduct a comprehensive study on CCsCe2Br7. The crystal structure of CsCe2Br7 is refined using single crystal X-ray study for the first time. It crystallizes into the orthorhombic crystal system with Pmnb space group. Its electronic structure is revealed by Density Functional Theory (DFT) calculations. Two cerium emission centers are identified and the energy barriers related to the thermal quenching to 4f ground states of Ce3+ for these two Ce centers are evaluated. CsCe2Br7 single crystal has better light yield and energy resolution than CsCe2Cl7, but with an additional slow decay component of 1.7 s. The existence of a deep trap with a depth of 0.9 eV in CsCe2Cl7 contributes to its higher afterglow level in comparison to that of CsCe2Br7. The most possible point defects in CsCe2Cl7 and CsCe2Br7 are proposed by considering the vapour pressure in the growth atmosphere upon melting point.

  3. Dual-energy micro-CT with a dual-layer, dual-color, single-crystal scintillator.

    PubMed

    Maier, Daniel Simon; Schock, Jonathan; Pfeiffer, Franz

    2017-03-20

    A wide range of X-ray imaging applications demand micrometer spatial resolution. In material science and biology especially, there is a great interest in material determination and material separation methods. Here we present a new detector design that allows the recording of a low- and a high-energy radiography image simultaneously with micrometer spatial resolution. The detector system is composed of a layered scintillator stack, two CCDs and an optical system to image the scintillator responses onto the CCDs. We used the detector system with a standard laboratory microfocus X-ray tube to prove the working principle of the system and derive important design characteristics. With the recorded and registered dual-energy data set, the material separation and determination could be shown at an X-ray tube peak energy of up to 160 keV with a spatial resolution of 12 μm. The detector design shows a great potential for further development and a wide range of possible applications.

  4. WE-C-217BCD-11: Coupled Radiative and Optical Geant4 Simulation of MV EPIDs Based on Thick Pixelated Scintillating Crystals.

    PubMed

    Constantin, D; Sun, M; Abel, E; Star-Lack, J; Fahrig, R

    2012-06-01

    One way to greatly reduce the incidence of metal artifacts produced in kilovoltage (kV) CT images is by using megavoltage (MV) photons that penetrate high-Z objects, thus providing a measurable signal. For do se-efficient imaging, a high detective quantum efficiency (DQE) MV detector is desired. This study validates the coupled radiation and optical Geant4 simulation results against experimental data from various prototype pixelated scintillator MV detectors and determines the essential optical parameters which control the detector performance. Experimental data obtained with a 6MV radiation source from 8 different detectors was considered. The detectors used CsI, CdW and BGO as scintillating crystals and polystyrene septal wall material. Accurate Geant4 models of the detectors were implemented and coupled radiation and optical simulations were performed. The unknown optical properties of the models were determined by minimizing the difference between the modulation transfer functions (MTF) of the simulated data obtained with the slanted slit technique and the experimental MTFs. With the set of optical properties fixed, further simulation validation was performed against the experimental normalized noise power spectrum (NNPS(f)) and the experimental DQE(f) curves for each detector. All the simulations were performed on a computer cluster deployed on the Amazon EC2 platform. The optimal values for the free optical parameters are 10%, 95% and 90% for the top surface reflectivity, the crystal-sept a surface reflectivity, and the Lambertian component contribution to the reflected beam from the crystal-septa interface respectively. The absolute difference between experimental and simulated data was below 10% for all the data sets. To our knowledge this study is the first to present a full optical and radiative DQE(f) model using Geant4 that shows an excellent match with experimental data. The model indicates that improved performance can be obtained using more specular

  5. New Scintillators for Photosensitive Gaseous Detectors

    NASA Astrophysics Data System (ADS)

    Charpak, G.; Peskov, V.; Scigocki, D.; Valbis, J.

    A new family of scintillators are presented. Their properties are similar to those of barium fluoride, and the spectrum of the scintillation emission is between 140 and 300 nm. Our latest efficiency measurements of ethyl ferrocene and triethylamine liquid or caesium iodide solid photocathodes, in parallel-plate avalanche chambers (PPACs) at high electric field, are also presented. We discuss the revolutionary consequences of the combination of the new scintillators with PPACs with semitransparent photocathodes deposited on the crystals, such as high speed, high resistance to radiation damage, compacity, high gamma efficiency, and applications to tracking devices with scintillation optical fibres.

  6. Crystal structure and thermal expansion of a CsCe2Cl7 scintillator

    SciTech Connect

    Zhuravleva, M.; Lindsey, A.; Chakoumakos, B. C.; Custelcean, R.; Meilleur, F.; Hughes, R. W.; Kriven, W. M.; Melcher, C. L.

    2015-04-06

    Here we used single-crystal X-ray diffraction data to determine crystal structure of CsCe2Cl7. It crystallizes in a P1121/b space group with a = 19.352(1) Å, b = 19.352(1) Å, c = 14.838(1) Å, γ = 119.87(2) ° , and V = 4818.6(5) Å3. Differential scanning calorimetry measurements combined with the structural evolution of CsCe2Cl7 via X-ray diffractometry over a temperature range from room temperature to the melting point indicates no obvious intermediate solid-solid phase transitions. The anisotropy in the average linear coefficient of thermal expansion of the a axis (21.3 10-6/ °C) with respect to the b and c axes (27.0 10-6/ °C) was determined through lattice parameter refinement of the temperature dependent diffraction patterns. Lastly, these findings suggest that the reported cracking behavior during melt growth of CsCe2Cl7 bulk crystals using conventional Bridgman and Czochralski techniques may be largely attributed to the anisotropy in thermal expansion.

  7. Crystal structure and thermal expansion of a CsCe{sub 2}Cl{sub 7} scintillator

    SciTech Connect

    Zhuravleva, M.; Lindsey, A.; Chakoumakos, B.C.; Custelcean, R.; Meilleur, F.; Hughes, R.W.; Kriven, W.M.; Melcher, C.L.

    2015-07-15

    We used single-crystal X-ray diffraction data to determine crystal structure of CsCe{sub 2}Cl{sub 7}. It crystallizes in a P112{sub 1}/b space group with a=19.352(1) Å, b=19.352(1) Å, c=14.838(1) Å, γ=119.87(2)°, and V=4818.6(5) Å{sup 3}. Differential scanning calorimetry measurements combined with the structural evolution of CsCe{sub 2}Cl{sub 7} via X-ray diffractometry over a temperature range from room temperature to the melting point indicates no obvious intermediate solid–solid phase transitions. The anisotropy in the average linear coefficient of thermal expansion of the a axis (21.3×10{sup –6}/°C) with respect to the b and c axes (27.0×10{sup –6}/°C) was determined through lattice parameter refinement of the temperature dependent diffraction patterns. These findings suggest that the reported cracking behavior during melt growth of CsCe{sub 2}Cl{sub 7} bulk crystals using conventional Bridgman and Czochralski techniques may be largely attributed to the anisotropy in thermal expansion. - Graphical abstract: Three-dimensional quadric surface of thermal expansion coefficient of CsCe{sub 2}Cl{sub 7} at room temperature (sphere – isotropic) and near melting point (ellipsoid – anisotropic). - Highlights: • Crystal structure of CsCe{sub 2}Cl{sub 7} was solved through X-ray diffraction. • Linear coefficients of thermal expansion were determined from in-situ XRD in 25–650 °C. • Anisotropy of the a axis with respect to b and c axes (21.3 vs 27.0×10{sup –6}/°C) was found. • No solid–solid phase transitions were observed via XRD and thermal analysis.

  8. High resolution scintillation detector with semiconductor readout

    DOEpatents

    Levin, Craig S.; Hoffman, Edward J.

    2000-01-01

    A novel high resolution scintillation detector array for use in radiation imaging such as high resolution Positron Emission Tomography (PET) which comprises one or more parallelepiped crystals with at least one long surface of each crystal being in intimate contact with a semiconductor photodetector such that photons generated within each crystal by gamma radiation passing therethrough is detected by the photodetector paired therewith.

  9. Development of Novel Polycrystalline Ceramic Scintillators

    SciTech Connect

    Wisniewska, Monika; Boatner, Lynn A; Neal, John S; Jellison Jr, Gerald Earle; Ramey, Joanne Oxendine; North, Andrea L; Wisniewski, Monica; Payzant, E Andrew; Howe, Jane Y; Lempicki, Aleksander; Brecher, Charlie; Glodo, J.

    2008-01-01

    For several decades most of the efforts to develop new scintillator materials have concentrated on high-light-yield inorganic single-crystals while polycrystalline ceramic scintillators, since their inception in the early 1980 s, have received relatively little attention. Nevertheless, transparent ceramics offer a promising approach to the fabrication of relatively inexpensive scintillators via a simple mechanical compaction and annealing process that eliminates single-crystal growth. Until recently, commonly accepted concepts restricted the polycrystalline ceramic approach to materials exhibiting a cubic crystal structure. Here, we report our results on the development of two novel ceramic scintillators based on the non-cubic crystalline materials: Lu SiO:Ce (LSO:Ce) and LaBr:Ce. While no evidence for texturing has been found in their ceramic microstructures, our LSO:Ce ceramics exhibit a surprisingly high level of transparency/ translucency and very good scintillation characteristics. The LSO:Ce ceramic scintillation reaches a light yield level of about 86% of that of a good LSO:Ce single crystal, and its decay time is even faster than in single crystals. Research on LaBr:Ce shows that translucent ceramics of the high-light-yield rare-earth halides can also be synthesized. Our LaBr:Ce ceramics have light yields above 42 000 photons/MeV (i.e., 70%of the single-crystal light yield).

  10. Investigation of double beta decay of {sup 116}Cd with the help of enriched {sup 116}CdWO{sub 4} crystal scintillators

    SciTech Connect

    Polischuk, O. G. Tretyak, V. I.; Barabash, A. S.; Konovalov, S. I.; Umatov, V. I.; Belli, P.; Bernabei, R.; D’Angelo, S.; Cappella, F.; Caracciolo, V.; Cerulli, R.; Laubenstein, M.; Chernyak, D. M.; Danevich, F. A.; Kobychev, V. V.; Mokina, V. M.; Incicchitti, A.; Poda, D. V.; Shlegel, V. N.; Vasiliev, Ya. V.

    2015-10-28

    An experiment to search for 2β processes in {sup 116}Cd with the help of enriched (to 82%) cadmium tungstate crystal scintillators is in progress at the Gran Sasso National Laboratory of the INFN (LNGS, Italy). After 11074 h of data taking in the last configuration, the preliminary estimate for the half-life of 116Cd relatively to 2ν2β decay is T{sub 1/2} = [2.52 ± 0.02(stat.) ± 0.14(syst.)] × 10{sup 19} yr. By using the data of previous stages of the experiment with a similar level of background (≈ 0.1 counts/(keV kg yr) in the energy interval 2.7 – 2.9 MeV; the total time of measurements is 19770 h) we have obtained a new limit on the 0ν2β decay of {sup 116}Cd to the ground state of {sup 116}Sn: T{sub 1/2} ≥ 1.9 × 10{sup 23} yr at 90% C.L. New limits on different 2β processes in {sup 116}Cd (decays with majorons, transitions to the excited levels) are obtained on the level of T{sub 1/2} ≥ 10{sup 20} – 10{sup 22} yr.

  11. Plastic scintillation dosimetry: Optimal selection of scintillating fibers and scintillators

    SciTech Connect

    Archambault, Louis; Arsenault, Jean; Gingras, Luc; Sam Beddar, A.; Roy, Rene; Beaulieu, Luc

    2005-07-15

    Scintillation dosimetry is a promising avenue for evaluating dose patterns delivered by intensity-modulated radiation therapy plans or for the small fields involved in stereotactic radiosurgery. However, the increase in signal has been the goal for many authors. In this paper, a comparison is made between plastic scintillating fibers and plastic scintillator. The collection of scintillation light was measured experimentally for four commercial models of scintillating fibers (BCF-12, BCF-60, SCSF-78, SCSF-3HF) and two models of plastic scintillators (BC-400, BC-408). The emission spectra of all six scintillators were obtained by using an optical spectrum analyzer and they were compared with theoretical behavior. For scintillation in the blue region, the signal intensity of a singly clad scintillating fiber (BCF-12) was 120% of that of the plastic scintillator (BC-400). For the multiclad fiber (SCSF-78), the signal reached 144% of that of the plastic scintillator. The intensity of the green scintillating fibers was lower than that of the plastic scintillator: 47% for the singly clad fiber (BCF-60) and 77% for the multiclad fiber (SCSF-3HF). The collected light was studied as a function of the scintillator length and radius for a cylindrical probe. We found that symmetric detectors with nearly the same spatial resolution in each direction (2 mm in diameter by 3 mm in length) could be made with a signal equivalent to those of the more commonly used asymmetric scintillators. With augmentation of the signal-to-noise ratio in consideration, this paper presents a series of comparisons that should provide insight into selection of a scintillator type and volume for development of a medical dosimeter.

  12. Plastic scintillation dosimetry: Optimal selection of scintillating fibers and scintillators.

    PubMed

    Archambault, Louis; Arsenault, Jean; Gingras, Luc; Sam Beddar, A; Roy, René; Beaulieu, Luc

    2005-07-01

    Scintillation dosimetry is a promising avenue for evaluating dose patterns delivered by intensity-modulated radiation therapy plans or for the small fields involved in stereotactic radiosurgery. However, the increase in signal has been the goal for many authors. In this paper, a comparison is made between plastic scintillating fibers and plastic scintillator. The collection of scintillation light was measured experimentally for four commercial models of scintillating fibers (BCF-12, BCF-60, SCSF-78, SCSF-3HF) and two models of plastic scintillators (BC-400, BC-408). The emission spectra of all six scintillators were obtained by using an optical spectrum analyzer and they were compared with theoretical behavior. For scintillation in the blue region, the signal intensity of a singly clad scintillating fiber (BCF-12) was 120% of that of the plastic scintillator (BC-400). For the multiclad fiber (SCSF-78), the signal reached 144% of that of the plastic scintillator. The intensity of the green scintillating fibers was lower than that of the plastic scintillator: 47% for the singly clad fiber (BCF-60) and 77% for the multiclad fiber (SCSF-3HF). The collected light was studied as a function of the scintillator length and radius for a cylindrical probe. We found that symmetric detectors with nearly the same spatial resolution in each direction (2 mm in diameter by 3 mm in length) could be made with a signal equivalent to those of the more commonly used asymmetric scintillators. With augmentation of the signal-to-noise ratio in consideration, this paper presents a series of comparisons that should provide insight into selection of a scintillator type and volume for development of a medical dosimeter. © 2005 American Association of Physicists in Medicine.

  13. Plastic scintillation dosimetry: optimal selection of scintillating fibers and scintillators.

    PubMed

    Archambault, Louis; Arsenault, Jean; Gingras, Luc; Beddar, A Sam; Roy, René; Beaulieu, Luc

    2005-07-01

    Scintillation dosimetry is a promising avenue for evaluating dose patterns delivered by intensity-modulated radiation therapy plans or for the small fields involved in stereotactic radiosurgery. However, the increase in signal has been the goal for many authors. In this paper, a comparison is made between plastic scintillating fibers and plastic scintillator. The collection of scintillation light was measured experimentally for four commercial models of scintillating fibers (BCF-12, BCF-60, SCSF-78, SCSF-3HF) and two models of plastic scintillators (BC-400, BC-408). The emission spectra of all six scintillators were obtained by using an optical spectrum analyzer and they were compared with theoretical behavior. For scintillation in the blue region, the signal intensity of a singly clad scintillating fiber (BCF-12) was 120% of that of the plastic scintillator (BC-400). For the multiclad fiber (SCSF-78), the signal reached 144% of that of the plastic scintillator. The intensity of the green scintillating fibers was lower than that of the plastic scintillator: 47% for the singly clad fiber (BCF-60) and 77% for the multiclad fiber (SCSF-3HF). The collected light was studied as a function of the scintillator length and radius for a cylindrical probe. We found that symmetric detectors with nearly the same spatial resolution in each direction (2 mm in diameter by 3 mm in length) could be made with a signal equivalent to those of the more commonly used asymmetric scintillators. With augmentation of the signal-to-noise ratio in consideration, this paper presents a series of comparisons that should provide insight into selection of a scintillator type and volume for development of a medical dosimeter.

  14. Cresst-II: dark matter search with scintillating absorbers

    NASA Astrophysics Data System (ADS)

    Angloher, G.; Bucci, C.; Cozzini, C.; von Feilitzsch, F.; Frank, T.; Hauff, D.; Henry, S.; Jagemann, Th.; Jochum, J.; Kraus, H.; Majorovits, B.; Ninkovic, J.; Petricca, F.; Pröbst, F.; Ramachers, Y.; Rau, W.; Seidel, W.; Stark, M.; Uchaikin, S.; Stodolsky, L.; Wulandari, H.

    2004-03-01

    In the CRESST-II experiment, scintillating CaWO4 crystals are used as absorbers for direct weakly interacting massive particles (WIMP) detection. Nuclear recoils can be discriminated against electron recoils by measuring phonons and scintillation light simultaneously. The absorber crystal and the silicon light detector are read out by tungsten superconducting phase transition thermometers. Results on the sensitivity of the phonon and the light channel, radiopurity, the scintillation properties of CaWO4, and on the WIMP sensitivity are presented.

  15. Hygroscopicity Evaluation of Halide Scintillators

    SciTech Connect

    Zhuravleva, M; Stand, L; Wei, H; Hobbs, C. L.; Boatner, Lynn A; Ramey, Joanne Oxendine; Burger, Arnold; Rowe, E; Bhattacharya, P.; Tupitsyn, E; Melcher, Charles L

    2014-01-01

    A collaborative study of relative hygroscopicity of anhydrous halide scintillators grown at various laboratories is presented. We have developed a technique to evaluate moisture sensitivity of both raw materials and grown crystals, in which the moisture absorption rate is measured using a gravimetric analysis. Degradation of the scintillation performance was investigated by recording gamma-ray spectra and monitoring the photopeak position, count rate and energy resolution. The accompanying physical degradation of the samples exposed to ambient atmosphere was photographically recorded as well. The results were compared with ben

  16. Characterization of the scintillation anisotropy in crystalline stilbene scintillator detectors

    SciTech Connect

    Schuster, P.; Brubaker, E.

    2016-11-23

    This study reports a series of measurements that characterize the directional dependence of the scintillation response of crystalline melt-grown and solution-grown trans-stilbene to incident DT and DD neutrons. These measurements give the amplitude and pulse shape dependence on the proton recoil direction over one hemisphere of the crystal, confirming and extending previous results in the literature for melt-grown stilbene and providing the first measurements for solution-grown stilbene. In similar measurements of liquid and plastic detectors, no directional dependence was observed, confirming the hypothesis that the anisotropy in stilbene and other organic crystal scintillators is a result of internal effects due to the molecular or crystal structure and not an external effect on the measurement system.

  17. Characterization of the scintillation anisotropy in crystalline stilbene scintillator detectors

    DOE PAGES

    Schuster, P.; Brubaker, E.

    2016-11-23

    This study reports a series of measurements that characterize the directional dependence of the scintillation response of crystalline melt-grown and solution-grown trans-stilbene to incident DT and DD neutrons. These measurements give the amplitude and pulse shape dependence on the proton recoil direction over one hemisphere of the crystal, confirming and extending previous results in the literature for melt-grown stilbene and providing the first measurements for solution-grown stilbene. In similar measurements of liquid and plastic detectors, no directional dependence was observed, confirming the hypothesis that the anisotropy in stilbene and other organic crystal scintillators is a result of internal effects duemore » to the molecular or crystal structure and not an external effect on the measurement system.« less

  18. Characterization of the scintillation anisotropy in crystalline stilbene scintillator detectors

    NASA Astrophysics Data System (ADS)

    Schuster, P.; Brubaker, E.

    2017-07-01

    This paper reports a series of measurements that characterize the directional dependence of the scintillation response of crystalline melt-grown and solution-grown trans-stilbene to incident DT and DD neutrons. These measurements give the amplitude and pulse shape dependence on the proton recoil direction over one hemisphere of the crystal, confirming and extending previous results in the literature for melt-grown stilbene and providing the first measurements for solution-grown stilbene. In similar measurements of liquid and plastic detectors, no directional dependence was observed, confirming the hypothesis that the anisotropy in stilbene and other organic crystal scintillators is a result of internal effects due to the molecular or crystal structure and not an external effect on the measurement system.

  19. Non-Carbon Dyes For Platic Scintillators- Report

    SciTech Connect

    Teprovich, J.; Colon-Mercado, H.; Gaillard, J.; Sexton, L.; Washington, A.; Ward, P.; Velten, J.

    2015-10-19

    Scintillation based detectors are desirable for many radiation detection applications (portal and border monitoring, safeguards verification, contamination detection and monitoring). The development of next generation scintillators will require improved detection sensitivity for weak gamma ray sources, and fast and thermal neutron quantification. Radiation detection of gamma and neutron sources can be accomplished with organic scintillators, however, the single crystals are difficult to grow for large area detectors and subject to cracking. Alternatives to single crystal organic scintillators are plastic scintillators (PS) which offer the ability to be shaped and scaled up to produce large sized detectors. PS is also more robust than the typical organic scintillator and are ideally suited for deployment in harsh real-world environments. PS contain a mixture of dyes to down-convert incident radiation into visible light that can be detected by a PMT. This project will evaluate the potential use of nano-carbon dyes in plastic scintillators.

  20. Estimation of Fano factor in inorganic scintillators

    PubMed Central

    Bora, Vaibhav; Barrett, Harrison H.; Fastje, David; Clarkson, Eric; Furenlid, Lars; Bousselham, Abdelkader; Shah, Kanai S.; Glodo, Jarek

    2015-01-01

    The Fano factor of an integer-valued random variable is defined as the ratio of its variance to its mean. Correlation between the outputs of two photomultiplier tubes on opposite faces of a scintillation crystal was used to estimate the Fano factor of photoelectrons and scintillation photons. Correlations between the integrals of the detector outputs were used to estimate the photoelectron and photon Fano factor for YAP:Ce, SrI2:Eu and CsI:Na scintillator crystals. At 662 keV, SrI2:Eu was found to be sub-Poisson, while CsI:Na and YAP:Ce were found to be super-Poisson. An experiment setup inspired from the Hanbury Brown and Twiss experiment was used to measure the correlations as a function of time between the outputs of two photomultiplier tubes looking at the same scintillation event. A model of the scintillation and the detection processes was used to generate simulated detector outputs as a function of time for different values of Fano factor. The simulated outputs from the model for different Fano factors was compared to the experimentally measured detector outputs to estimate the Fano factor of the scintillation photons for YAP:Ce, LaBr3:Ce scintillator crystals. At 662 keV, LaBr3:Ce was found to be sub-Poisson, while YAP:Ce was found to be close to Poisson. PMID:26644631

  1. Energy resolution measurements of LaBr 3:Ce scintillating crystals with an ultra-high quantum efficiency photomultiplier tube

    NASA Astrophysics Data System (ADS)

    Pani, R.; Cinti, M. N.; Scafè, R.; Pellegrini, R.; Vittorini, F.; Bennati, P.; Ridolfi, S.; Lo Meo, S.; Mattioli, M.; Baldazzi, G.; Pisacane, F.; Navarria, F.; Moschini, G.; Boccaccio, P.; Orsolini Cencelli, V.; Sacco, D.

    2009-10-01

    The performance of the new prototype of high quantum efficiency PMT (43% at 380 nm), Hamamatsu R7600U-200, was studied coupled to a LaBr 3:Ce crystal with the size of ∅12.5 mm×12.5 mm. The energy resolution results were compared with ones from two PMTs, Hamamatsu R7600U and R6231MOD, with 22% and 30% quantum efficiency (QE), respectively. Moreover, the photodetectors were equipped with tapered and un-tapered voltage dividers to study the non-linearity effects on pulse height distribution, due to very high peak currents induced in the PMT by the fast and intense light pulse of LaBr 3:Ce. The results show an energy resolution improvement with UBA PMT of about 20%, in the energy range of 80-662 keV, with respect to the BA one.

  2. Fracture-resistant lanthanide scintillators

    DOEpatents

    Doty, F Patrick [Livermore, CA

    2011-01-04

    Lanthanide halide alloys have recently enabled scintillating gamma ray spectrometers comparable to room temperature semiconductors (<3% FWHM energy resolutions at 662 keV). However brittle fracture of these materials upon cooling hinders the growth of large volume crystals. Efforts to improve the strength through non-lanthanide alloy substitution, while preserving scintillation, have been demonstrated. Isovalent alloys having nominal compositions of comprising Al, Ga, Sc, Y, and In dopants as well as aliovalent alloys comprising Ca, Sr, Zr, Hf, Zn, and Pb dopants were prepared. All of these alloys exhibit bright fluorescence under UV excitation, with varying shifts in the spectral peaks and intensities relative to pure CeBr.sub.3. Further, these alloys scintillate when coupled to a photomultiplier tube (PMT) and exposed to .sup.137Cs gamma rays.

  3. Multilayer passive shielding of scintillation detectors based on BGO, NaI(Tl), and stilbene crystals operating in intense neutron fields with an energy of 14.1 MeV

    NASA Astrophysics Data System (ADS)

    Bystritsky, V. M.; Valkovic, V.; Grozdanov, D. N.; Zontikov, A. O.; Ivanov, I. Zh.; Kopatch, Yu. N.; Krylov, A. R.; Rogov, Yu. N.; Ruskov, I. N.; Sapozhnikov, M. G.; Skoy, V. R.; Shvetsov, V. N.

    2015-03-01

    We discuss the issues related to choosing the optimum type of passive shielding of scintillation detectors based on BGO, NaI(Tl), and stilbene crystals from the direct penetration of neutron radiation with an energy of 14.1 MeV that was emitted isotropically into a solid angle of 4π. A series of experimental measurements of the count-rate suppression factor that may be obtained for the indicated detectors through the use of various shielding filters comprising iron, lead, and borated polyethylene layers with a total thickness not exceeding 50 cm are conducted.

  4. Energy Transfer Based Nanocomposite Scintillator for Radiation Detection

    NASA Astrophysics Data System (ADS)

    Aslam, Soha; Sahi, Sunil; Chen, Wei; Ma, Lun; Kenarangui, Rasool

    2014-09-01

    Scintillators are the materials that emit light upon irradiation with high energy radiation like X-ray or gamma-ray. Inorganic single crystal and organic (plastic and liquid) are the two most used scintillator types. Both of these scintillator kinds have advantages and disadvantages. Inorganic single crystals are expensive and difficult to grow in desire shape and size. Also, single crystal scintillator such as NaI and CsI are very hygroscopic. On the other hand, organic scintillators have low density which limits their applications in gamma spectroscopy. Due to high quantum yield and size dependent emission, nanoparticles have attracted interested in various field of research. Here, we have studies the nanoparticles for radiation detection. We have synthesized nanoparticles of Cerium fluoride (CeF3), Zinc Oxide (ZnO), Cadmium Telluride (CdTe), Copper complex and Zinc sulfide (ZnS). We have used Fluorescence Resonance Energy Transfer (FRET) principle to enhance the luminescence properties of nanocomposite scintillator. Nanocomposites scintillators are structurally characterized with X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). Optical properties are studied using Photoluminescence, UV-Visible and X-ray. Enhancements in the luminescence are observed under UV and X-ray excitation. Preliminary studies shows nanocomposite scintillators are promising for radiation detection. Scintillators are the materials that emit light upon irradiation with high energy radiation like X-ray or gamma-ray. Inorganic single crystal and organic (plastic and liquid) are the two most used scintillator types. Both of these scintillator kinds have advantages and disadvantages. Inorganic single crystals are expensive and difficult to grow in desire shape and size. Also, single crystal scintillator such as NaI and CsI are very hygroscopic. On the other hand, organic scintillators have low density which limits their applications in gamma spectroscopy. Due to high quantum

  5. Optical transmission radiation damage and recovery stimulation of DSB: Ce3+ inorganic scintillation material

    NASA Astrophysics Data System (ADS)

    Borisevich, A.; Dormenev, V.; Korjik, M.; Kozlov, D.; Mechinsky, V.; Novotny, R. W.

    2015-02-01

    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.

  6. Scintillators and applications thereof

    DOEpatents

    Williams, Richard T.

    2015-09-01

    Scintillators of various constructions and methods of making and using the same are provided. In some embodiments, a scintillator comprises at least one radiation absorption region and at least one spatially discrete radiative exciton recombination region.

  7. Scintillators and applications thereof

    DOEpatents

    Williams, Richard T.

    2014-07-15

    Scintillators of various constructions and methods of making and using the same are provided. In some embodiments, a scintillator comprises at least one radiation absorption region and at least one spatially discrete radiative exciton recombination region.

  8. High latitude scintillations

    NASA Astrophysics Data System (ADS)

    Basu, Santimay; Basu, Sunanda

    High-latitude phase and amplitude scintillations have been observed with quasi-geostationary polar beacon satellites, high-altitude orbiting GPS satellites, and low-altitude orbiting HiLat and Polar Bear satellites. The scintillation behavior observed in the polar cap, cusp, and nightside auroral oval is described. Consideration is given to the possible mechanisms for the generation of irregularities that cause scintillations. The importance of coordinated multitechnique measurements for scintillation studies is stressed.

  9. Design studies of the PWO Forward End-cap calorimeter for P¯ANDA

    NASA Astrophysics Data System (ADS)

    Moeini, H.; Al-Turany, M.; Babai, M.; Biegun, A.; Bondarenko, O.; Götzen, K.; Kavatsyuk, M.; Lindemulder, M. F.; Löhner, H.; Melnychuk, D.; Messchendorp, J. G.; Smit, H. A. J.; Spataro, S.; Veenstra, R.

    2013-11-01

    The P¯ANDA detection system at FAIR, Germany, is designed to study antiproton-proton annihilations, in order to investigate, among others, the realm of charm-meson states and glueballs, which has still much to reveal. The yet unknown properties of this field are to be unraveled through studying QCD phenomena in the non-perturbative regime. The multipurpose P¯ANDA detector will be capable of tracking, calorimetry, and particle identification, and is planned to run at high luminosities providing average reaction rates up to 2 · 107 interactions/s. The envisaged physics program requires measurements of photons and charged particles with excellent energy, position, and time resolutions. The electromagnetic calorimeter (EMC) will serve as one of the basic components of the detector setup and comprises cooled lead-tungstate (PbWO4) crystals. This paper presents the mechanical design of the Forward End-cap calorimeter and analyzes the response of the Forward End-cap calorimeter in conjunction with the full EMC and the complete P¯ANDA detector. The simulation studies are focused on the performance of the planned EMC with respect to the energy and spatial resolution of the reconstructed photons. Results of the Monte Carlo simulations, excluding very low-energy photons, have been validated by data obtained from a prototype calorimeter and shown to fulfil the requirements imposed by the P¯ANDA physics program.

  10. Scintillator manufacture at Fermilab

    SciTech Connect

    Mellott, K.; Bross, A.; Pla-Dalmau, A.

    1998-08-01

    A decade of research into plastic scintillation materials at Fermilab is reviewed. Early work with plastic optical fiber fabrication is revisited and recent experiments with large-scale commercial methods for production of bulk scintillator are discussed. Costs for various forms of scintillator are examined and new development goals including cost reduction methods and quality improvement techniques are suggested.

  11. Lead carbonate scintillator materials

    DOEpatents

    Derenzo, Stephen E.; Moses, William W.

    1991-01-01

    Improved radiation detectors containing lead carbonate or basic lead carbonate as the scintillator element are disclosed. Both of these scintillators have been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to other known scintillator materials. The radiation detectors disclosed are favorably suited for use in general purpose detection and in medical uses.

  12. Scintillator manufacture at Fermilab

    NASA Astrophysics Data System (ADS)

    Mellott, K.; Bross, A.; Pla-Dalmau, A.

    1998-11-01

    A decade of research into plastic scintillation materials at Fermilab is reviewed. Early work with plastic optical fiber fabrication is revisited and recent experiments with large-scale commercial methods for production of bulk scintillator are discussed. Costs for various forms of scintillator are examined and new development goals including cost reduction methods and quality improvement techniques are suggested.

  13. Scintillation properties of polycrystalline LaxY1-xO3 ceramic

    NASA Astrophysics Data System (ADS)

    Sahi, Sunil; Chen, Wei; Kenarangui, Rasool

    2015-03-01

    Scintillators are the material that absorbs the high-energy photons and emits visible photons. Scintillators are commonly used in radiation detector for security, medical imaging, industrial applications and high energy physics research. Two main types of scintillators are inorganic single crystals and organic (plastic or liquid) scintillators. Inorganic single crystals are expensive and difficult to grow in desire shape and size. Also, some efficient inorganic scintillator such as NaI and CsI are not environmental friendly. But on the other hand, organic scintillators have low density and hence poor energy resolution which limits their use in gamma spectroscopy. Polycrystalline ceramic can be a cost effective alternative to expensive inorganic single crystal scintillators. Here we have fabricated La0.2Y1.8O3 ceramic scintillator and studied their luminescence and scintillation properties. Ceramic scintillators were fabricated by vacuum sintering of La0.2Y1.8O3 nanoparticles at temperature below the melting point. La0.2Y1.8O3 ceramic were characterized structurally using XRD and TEM. Photoluminescence and radioluminescence studies were done using UV and X-ray as an excitation source. We have used gamma isotopes with different energy to studies the scintillation properties of La0.2Y1.8O3 scintillator. Preliminary studies of La0.2Y1.8O3 scintillator shows promising result with energy resolution comparable to that of NaI and CsI.

  14. Scintillator reflective layer coextrusion

    DOEpatents

    Yun, Jae-Chul; Para, Adam

    2001-01-01

    A polymeric scintillator has a reflective layer adhered to the exterior surface thereof. The reflective layer comprises a reflective pigment and an adhesive binder. The adhesive binder includes polymeric material from which the scintillator is formed. A method of forming the polymeric scintillator having a reflective layer adhered to the exterior surface thereof is also provided. The method includes the steps of (a) extruding an inner core member from a first amount of polymeric scintillator material, and (b) coextruding an outer reflective layer on the exterior surface of the inner core member. The outer reflective layer comprises a reflective pigment and a second amount of the polymeric scintillator material.

  15. Elpasolite scintillators.

    SciTech Connect

    Doty, F. Patrick; Zhou, Xiao Wang; Yang, Pin; Rodriguez, Mark A

    2012-12-01

    This work was funded by the U.S. Department of Energy Office of Nonproliferation Research to develop elpasolite materials, with an emphasis on high-atomic-number rare-earth elpasolites for gamma-ray spectrometer applications. Low-cost, high-performance gamma-ray spectrometers are needed for detection of nuclear proliferation. Cubic materials, such as some members of the elpasolite family (A2BLnX6; Ln-lanthanide and X-halogen), hold promise due to their high light output, proportionality, and potential for scale-up. Using both computational and experimental studies, a systematic investigation of the compositionstructureproperty relationships of these high-atomic-number elpasolite halides was performed. The results reduce the barrier to commercialization of large single crystals or transparent ceramics, and will facilitate economical scale-up of elpasolites for high-sensitivity gamma-ray spectroscopy.

  16. Synthesis and characterization of nanocomposite scintillators for radiation detection

    NASA Astrophysics Data System (ADS)

    Sahi, Sunil Kumar

    Inorganic single crystal and organic (plastic and liquid) scintillators are commonly used for radiation detection. Inorganic single crystals are efficient and have better energy resolution compared to organic scintillators. However, inorganic single crystals are difficult to grow in large size and hence expensive. On the other hand, fast decay time and ease of fabrication makes organic scintillators attractive for many applications. However, poor energy resolution of organic scintillators limits its applications in gamma ray spectroscopy. The poor energy resolution is due to the low Z-value and low density of organic scintillator. The Z-value of organic plastic scintillator can be increase by loading nanoparticles in plastic matrix. It is expected that the increase in Z-value would result in improve energy resolution of nanocomposite scintillator. However, the loss of optical transparency due to nanoparticles loading is one of the major concerns of nanocomposite scintillators. In this dissertation, we used different methods to synthesize La xCe1-xF3 nanoparticles with high dispersion in polymer matrix. High nanoparticle dispersion is important to load high concentration of nanoparticles into polymer matrix without losing the transparency of the polymer matrix. The as synthesized nanoparticles are dispersed into monomers and polymerized using heat initiated bulk polymerization method. Nanoparticles are characterized using TEM, XRD, FTIR and TGA. The optical and scintillation properties of nanoparticles and nanocomposites are studied using spectroscopic techniques. The pulse height spectra obtained using nanocomposite fabricated by loading up to 30 wt% nanoparticles clearly show a photopeak for the 122 keV line of the Co-57 isotope. The generation of the photopeak is due to the enhanced photoelectric effect as a result of increased effective atomic number (Zeff) and density of nanocomposite scintillator. The pulse height spectra of Cs-137 gamma source show a full

  17. Recent development in organic scintillators

    NASA Technical Reports Server (NTRS)

    Horrocks, D. L.; Wirth, H. O.

    1969-01-01

    Discussion on recent developments of organic scintillators includes studies of organic compounds that form glass-like masses which scintillate and are stable at room temperature, correlations between molecular structure of organic scintillators and self-quenching, recently developed fast scintillators, and applications of liquid-scintillation counters.

  18. CRESST-II: dark matter search with scintillating absorbers

    NASA Astrophysics Data System (ADS)

    Angloher, G.; Bucci, C.; Cozzini, C.; von Feilitzsch, F.; Frank, T.; Hauff, D.; Henry, S.; Jagemann, Th.; Jochum, J.; Kraus, H.; Majorovits, B.; Ninkovic, J.; Petricca, F.; Pröbst, F.; Ramachers, Y.; Rau, W.; Seidel, W.; Stark, M.; Uchaikin, S.; Stodolsky, L.; Wulandari, H.

    2005-01-01

    In the CRESST-II experiment, scintillating CaWO 4 crystals are used as absorbers for direct WIMP (weakly interacting massive particles) detection. Nuclear recoils can be discriminated against electron recoils by measuring phonons and scintillation light simultaneously. The absorber crystal and the silicon light detector are read out by tungsten superconducting phase transition thermometers (W-SPTs). Results on the sensitivity of the phonon and the light channel, radiopurity, the scintillation properties of CaWO 4, and on the WIMP sensitivity are presented.

  19. Subnanosecond Scintillation Detector

    NASA Technical Reports Server (NTRS)

    Hoenk, Michael (Inventor); Hennessy, John (Inventor); Hitlin, David (Inventor)

    2017-01-01

    A scintillation detector, including a scintillator that emits scintillation; a semiconductor photodetector having a surface area for receiving the scintillation, wherein the surface area has a passivation layer configured to provide a peak quantum efficiency greater than 40% for a first component of the scintillation, and the semiconductor photodetector has built in gain through avalanche multiplication; a coating on the surface area, wherein the coating acts as a bandpass filter that transmits light within a range of wavelengths corresponding to the first component of the scintillation and suppresses transmission of light with wavelengths outside said range of wavelengths; and wherein the surface area, the passivation layer, and the coating are controlled to increase the temporal resolution of the semiconductor photodetector.

  20. Shifting scintillator neutron detector

    DOEpatents

    Clonts, Lloyd G; Cooper, Ronald G; Crow, Jr., Morris Lowell; Hannah, Bruce W; Hodges, Jason P; Richards, John D; Riedel, Richard A

    2014-03-04

    Provided are sensors and methods for detecting thermal neutrons. Provided is an apparatus having a scintillator for absorbing a neutron, the scintillator having a back side for discharging a scintillation light of a first wavelength in response to the absorbed neutron, an array of wavelength-shifting fibers proximate to the back side of the scintillator for shifting the scintillation light of the first wavelength to light of a second wavelength, the wavelength-shifting fibers being disposed in a two-dimensional pattern and defining a plurality of scattering plane pixels where the wavelength-shifting fibers overlap, a plurality of photomultiplier tubes, in coded optical communication with the wavelength-shifting fibers, for converting the light of the second wavelength to an electronic signal, and a processor for processing the electronic signal to identify one of the plurality of scattering plane pixels as indicative of a position within the scintillator where the neutron was absorbed.

  1. Study of equatorial scintillations

    NASA Technical Reports Server (NTRS)

    Pomalaza, J.; Woodman, R.; Tisnado, G.; Nakasone, E.

    1972-01-01

    Observations of the amplitude scintillations produced by the F-region in equatorial areas are presented. The equipment used for conducting the observations is described. The use of transmissions from the ATS-1, ATS-3, and ATS-5 for obtaining data is described. The two principal subjects discussed are: (1) correlation between satellite and incoherent radar observations of scintillations and (2) simultaneous observations of scintillations at 136 MHz and 1550 MHz.

  2. Lead carbonate scintillator materials

    DOEpatents

    Derenzo, S.E.; Moses, W.W.

    1991-05-14

    Improved radiation detectors containing lead carbonate or basic lead carbonate as the scintillator element are disclosed. Both of these scintillators have been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to other known scintillator materials. The radiation detectors disclosed are favorably suited for use in general purpose detection and in medical uses. 3 figures.

  3. Accelerated discovery of elpasolite scintillators

    SciTech Connect

    Doty, F. Patrick; Yang, Pin; Zhou, Xiaowang

    2014-12-01

    Elpasolite scintillators are a large family of halides which includes compounds reported to meet the NA22 program goals of <3% energy resolution at 662 keV1. This work investigated the potential to produce quality elpasolite compounds and alloys of useful sizes at reasonable cost, through systematic experimental and computational investigation of crystal structure and properties across the composition space. Discovery was accelerated by computational methods and models developed previously to efficiently identify cubic members of the elpasolite halides, and to evaluate stability of anion and cation exchange alloys.

  4. Characterization of 1.2×1.2 mm2 silicon photomultipliers with Ce:LYSO, Ce:GAGG, and Pr:LuAG scintillation crystals as detector modules for positron emission tomography

    NASA Astrophysics Data System (ADS)

    Omidvari, N.; Sharma, R.; Ganka, T. R.; Schneider, F. R.; Paul, S.; Ziegler, S. I.

    2017-04-01

    The design of a positron emission tomography (PET) scanner is specially challenging since it should not compromise high spatial resolution, high sensitivity, high count-rate capability, and good energy and time resolution. The geometrical design of the system alongside the characteristics of the individual PET detector modules contributes to the overall performance of the scanner. The detector performance is mainly influenced by the characteristics of the photo-detector and the scintillation crystal. Although silicon photomultipliers (SiPMs) have already proven to be promising photo-detectors for PET, their performance is highly influenced by micro-cell structure and production technology. Therefore, five types of SiPMs produced by KETEK with an active area size of 1.2 × 1.2 mm2 were characterized in this study. The SiPMs differed in the production technology and had micro-cell sizes of 25, 50, 75, and 100 μm. Performance of the SiPMs was evaluated in terms of their breakdown voltage, temperature sensitivity, dark count rate, and correlated noise probability. Subsequently, energy resolution and coincidence time resolution (CTR) of the SiPMs were measured with five types of crystals, including two Ce:LYSO, two Ce:GAGG, and one Pr:LuAG. Two crystals with a geometry of 1.5 × 1.5 × 6 mm3 were available from each type. The best CTR achieved was ~ 240 ps, which was obtained with the Ce:LYSO crystals coupled to the 50 μm SiPM produced with the trench technology. The best energy resolution for the 511 keV photo-peak was ~ 11% and was obtained with the same SiPM coupled to the Ce:GAGG crystals.

  5. Cathodoluminescence studies of commercial and nano-structured scintillators

    NASA Astrophysics Data System (ADS)

    McDoanld, Warren; McKinney, George; Tzolov, Marian

    2014-03-01

    Scintillators have applications in fundamental research and in consumer products, e.g. detectors, scanners, and televisions. This research focused on analyzing the cathodoluminescence of different single-crystal scintillators with an originally developed method for evaluation of their performance, which allows for a direct comparison of different scintillators. We have studied yttrium aluminum garnet (YAG), yttrium aluminum perovskite (YAP) scintillators, zinc oxide single crystal, zinc tungstate single crystal, zinc oxide nanowires, and zinc tungstate film. The commercial scintillators are covered with conductive film which prevents low energy electrons from effectively interacting with the scintillator. We have varied the voltage accelerating the electrons with the intention of finding the threshold below which this effect will impact the performance of the scintillators. The same procedure was followed for the nanowires and zinc tungstate film which have enough conductivity and don't require a top conducting film. The threshold was established to be around 3 kV for the YAG and there is no threshold for the films, which perform much better at these low voltages. This property of the films has the potential for application in desktop scanning electron microscopes, where the accelerating voltage is low. The voltage dependence of the cathodoluminescence intensity follows an exponential trend and we present a model explaining it.

  6. Purification of large liquid scintillators for Borexino

    SciTech Connect

    Benziger, J.B.; Calaprice, F.P.; Vogelaar, R.B.

    1993-10-01

    Distillation extraction and crystallization have been used on scintillator mixtures for solar neutrino physics to remove cosmo- genically produced impurities ({sup 7}Be) and naturally occurring impurities ({sup 238}U, {sup 232}Th, and {sup 40}K), and to improve the optical transmission. Distillation was effective at removing {sup 7}Be and other impurities from aromatic solvents (p-xylene and pseudocumene) used as scintillator solvents. Distillation also provided the greatest improvement in the optical clarity of the solvents. Commercially available fluors (PPO and PMP) have high levels of potassium, far in excess of those tolerable for Borexino. Extraction techniques have been found to be effective at removing radioactive impurities, particularly potassium, from the fluors. An overall strategy for on-line purification of the scintillator for Borexino will be presented.

  7. Development of a novel depth-of-interaction encoding method and use of light spreading in a scintillation crystal array with single-ended readout

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Jae; Lee, Chaeyeong; Chung, Yong Hyun; Kang, Jihoon; Baek, Cheol-Ha

    2016-12-01

    We designed a depth-of-interaction (DOI) positron emission tomography detector by applying a simple light-spreading method in a single-layer crystal array with a single-ended photosensor. By configuring different reflector patterns along the depth of the crystal, we were able to alter the light distribution of the gamma interaction at each depth. To evaluate the characteristics of the new DOI detector, we simulated the optical photon transport in the crystal array by using DETECT2000. Three different arrays comprising triangular-, square-, and hexagonal-shaped crystals were modeled. The 511-keV gamma-ray interactions were generated for all depths, and flood images were acquired. We confirmed that DOI layers could be distinguished in the obtained images and that the number of DOI layers depends on the number of sides of the polygonal crystals.

  8. Luminescence quenching and scintillation response in the Ce3+ doped GdxY3-xAl5O12 (x = 0.75, 1, 1.25, 1.5, 1.75, 2) single crystals

    NASA Astrophysics Data System (ADS)

    Bartosiewicz, K.; Babin, V.; Kamada, K.; Yoshikawa, A.; Mares, J. A.; Beitlerova, A.; Nikl, M.

    2017-01-01

    The luminescence and scintillation properties of the gadolinium yttrium aluminium garnets, (Gd,Y)3Al5O12 doped with Ce3+ are investigated as a function of the Gd/Y ratio with the aim of an improved understanding of the luminescence quenching, energy transfer and phase stability in these materials. An increase of both crystal field strength and instability of the garnet phase with increasing content of Gd3+ is observed. The instability of the garnet phase results in an appearance of the perovskite phase inclusions incorporated into the garnet phase. The luminescence features of Ce3+ in the perovskite phase inclusions and in the main garnet phase are studied separately. The thermal quenching of the 5 d → 4f emission of Ce3+ in the latter phase is determined by temperature dependence of the photoluminescence decay time. The results show that the onset of the thermal quenching is moved to lower temperatures with increasing gadolinium content. The measurements of temperature dependence of delayed radiative recombination do not reveal a clear evidence that the thermal quenching is caused by thermally induced ionization of the Ce3+ 5d1 excited state. Therefore, the main mechanism responsible for the luminescence quenching is due to the non-radiative relaxation from 5d1 excited state to 4f ground state of Ce3+. The energy transfer processes between Gd3+ and Ce3+ as well as between perovskite and garnet phases are evidenced by the photoluminescence excitation and emission spectra as well as decay kinetic measurements. Thermally stimulated luminescence (TSL) studies in the temperature range 77-497 K and scintillation decays under γ excitation complete the material characterization.

  9. Cryogenic Scintillators for Rare-Event Searches

    NASA Astrophysics Data System (ADS)

    Nadeau, Patrick

    Rare-event searches, such as the direct detection of dark matter, of neutrinoless double beta decay and of the decay of long-lived radioisotopes, require highly-sensitive radio-pure detectors to measure extremely rare interactions amidst a sea of background events coming from natural radioactivity. The DAMA/LIBRA dark matter experiment has a long-standing claim of detecting event excesses inconsistent with known background and attributes these to the annual modulation signature expected from dark matter interactions on Earth. The DAMA/LIBRA detector array is composed of NaI(Tl) scintillation detectors, which do not possess event-by-event background rejection capabilities. Scintillating calorimeters, cryogenic detectors based on scintillating crystals that produce simultaneous heat and light signals, are a promising detector technology capable of a powerful level of background rejection. Rare-event searches employing scintillating calorimeters are on the look-out for crystals with favourable low-temperature properties. This dissertation will describe the optical cryostat that our group has designed, commissioned, tested and is now operating at Queen's University for the purpose of studying samples of scintillating crystals and measuring their properties as a function of temperature. In particular, it details measurements of the light yields of the alkali halides NaI, CsI and NaI(Tl) under alpha- and gamma-excitation down to 3.4 K. The temperature response of the alpha/gamma quenching factors of these scintillators is also presented, along with surface-dependent systematics. Informed by these low-temperature scintillation results, a scintillating calorimeter based on alkali halides is proposed and its expected sensitivity to dark matter is studied. The technical feasibility of such a detector is also discussed. It is demonstrated that if technical challenges can be surmounted and the phonon performance of the alkali halides can be improved to the level of other

  10. THE CRYSTAL STRUCTURE OF 2,7-DIACETOXYTRANS-15,16-DIMETHYL-15,16-DIHYDROPYRENE,

    DTIC Science & Technology

    AROMATIC COMPOUNDS, CRYSTAL STRUCTURE ), (*POLYCYCLIC COMPOUNDS, CRYSTAL STRUCTURE ), (* CRYSTAL STRUCTURE , POLYCYCLIC COMPOUNDS), ESTERS, MOLECULAR STRUCTURE, CHEMICAL BONDS, X RAY DIFFRACTION, SCINTILLATION COUNTERS, CANADA

  11. Mercuric iodide photodetectors for scintillation spectroscopy

    SciTech Connect

    Markakis, J.; Dabrowski, A.; Iwanczyk, J.; Ortale, C.; Schnepple, W.

    1985-02-01

    We have measured the responses to /sup 137/Cs (662 keV) of both a 1-inch-diam by 2-inch-thick NaI(Tl) scintillator optically coupled to a 1-inch-diam by 800-..mu..mthick mercuric iodide (HgI/sub 2/) photodetector, and a 1-cmdiam by 1-cm-thick CaWO/sub 4/ scintillator coupled to a 1.3-cm-diam by 600-..mu..m-thick HgI/sub 2/ photodetector. Best spectral resolution to /sup 137/Cs was 7.8% FWHM for the NaI(Tl)-HgI/sub 2/ and 12.5% FWHM for the CaWO/sub 4/-HgI/sub 2/ detectors; peak-to-valley ratios were 26:1 and 16:1, respectively. HgI/sub 2/ detectors operate at room temperature and their use in scintillation spectroscopy presents the ultimate miniaturization of scintillation detectors, limited mainly by the size of the scintillation crystal.

  12. Mercuric iodide photodetectors for scintillation spectroscopy

    SciTech Connect

    Markakis, J.; Ortale, C.; Schnepple, W.; Iwanczyk, J.; Dabrowski, A.

    1984-01-01

    We have measured the responses to /sup 137/Cs (662 keV) of both a 1-inch-diam by 2-inch-thick NaI(Tl) scintillator optically coupled to a 1-inch-diam by 800-..mu..m-thick mercuric iodide (HgI/sub 2/) photodetector, and a 1-cm-diam by 1-cm-thick CaWO/sub 4/ scintillator coupled to a 1.3-cm-diam by 600-..mu..m-thick HgI/sub 2/ photodetector. Best spectral resolution to /sup 137/Cs was 7.8% FWHM for the NaI(Tl)-HgI/sub 2/ and 12.5% FWHM for the CaWO/sub 4/-HgI/sub 2/ detectors; peak-to-valley ratios were 26:1 and 16:1, respectively. HgI/sub 2/ detectors operate at room temperature and their use in scintillation spectroscopy presents the ultimate miniaturization of scintillation detectors, limited mainly by the size of the scintillation crystal.

  13. Thin film scintillators

    NASA Astrophysics Data System (ADS)

    McDonald, Warren; McKinney, George; Tzolov, Marian

    2015-03-01

    Scintillating materials convert energy flux (particles or electromagnetic waves) into light with spectral characteristic matching a subsequent light detector. Commercial scintillators such as yttrium aluminum garnet (YAG) and yttrium aluminum perovskite (YAP) are commonly used. These are inefficient at lower energies due to the conductive coating present on their top surface, which is needed to avoid charging. We hypothesize that nano-structured thin film scintillators will outperform the commercial scintillators at low electron energies. We have developed alternative thin film scintillators, zinc tungstate and zinc oxide, which show promise for higher sensitivity to lower energy electrons since they are inherently conductive. Zinc tungstate films exhibit photoluminescence quantum efficiency of 74%. Cathodoluminescence spectroscopy was applied in transmission and reflection geometries. The comparison between the thin films and the YAG and YAP commercial scintillators shows much higher light output from the zinc tungstate and zinc oxide at electron energies less than 5 keV. Our films were integrated in a backscattered electron detector. This detector delivers better images than an identical detector with commercial YAG scintillator at low electron energies. Dr. Nicholas Barbi from PulseTor LLC, Dr. Anura Goonewardene, NSF Grants: #0806660, #1058829, #0923047.

  14. A comparative study of gamma-ray spectrometers with LaBr3(Ce3+) and CeBr3 scintillation crystals for planetary remote sensing applications.

    NASA Astrophysics Data System (ADS)

    Kozyrev, Alexander; Mitrofanov, Igor; Owens, Alan; Quarati, Francesco; Benkhoff, Johannes; Litvak, Maxim; Malakhov, Alexey; Mokrousov, Maxim; Vostrukhin, Andrey; Golovin, Dmitry; Tretyakov, Vladislav; Sanin, Anton; Bakhtin, Boris; Timoshenko, Gennady; Shvetsov, Valery; Granja, Carlos; Slavicek, Tomáš; Pospisil, Stanislav

    2016-04-01

    The Russian Space Research Institute has developed and manufactured the gamma-ray spectrometer MGNS for remote sensing observations of the Mercury from the Mercury Polar Orbiter (MPO), which is the part of ESA's BepiColombo mission. The Flight Model (FM) of MGNS is based on a 3-inch single crystal of LaBr3(Ce3+), which was produced in the crystal development programme specifically for this mission. During the instrument development and verification, the crystals of CeBr3(Ce3+) became available with the similar sizes in a subsequent phase of the same crystal development programme. Consequently, the Flight Spare Model (FSM) of MGNS was produced with the 3-inch CeBr3 crystal and qualified for space flight. Except for the crystals, the two units FM and FSM are essentially identical. We report the results on a comparative assessment of the two units in terms of their respective spectroscopic capabilities, well as for their suitability for interplanetary spacecraft with respect to radiation tolerance and redundancy for activation. We also compare their performance with that of the Ge detector, as one used on the Messenger mission. Based on the tests results, the decision was taken to use FSM onboard the MPO on the BepiColombo mission. Thus, the MGNS with CeBr3 is the central gamma-ray detection element on the MPO spacecraft.

  15. Simulation of scintillation light output in LYSO scintillators through a full factorial design

    NASA Astrophysics Data System (ADS)

    Loignon-Houle, Francis; Bergeron, Mélanie; Pepin, Catherine M.; Charlebois, Serge A.; Lecomte, Roger

    2017-01-01

    Individually coupled scintillation detectors used in positron emission tomography (PET) imaging suffer from important signal losses due to the suboptimal light collection from crystals. As only a fraction of the light is generally extracted from long and thin scintillators, it is important to identify and understand the predominant causes of signal loss in order to eventually recover it. This simulation study investigates the multiple factors affecting the light transport in high-aspect ratio LYSO scintillators wrapped in specular reflectors through a full factorial design. By exploring various combinations of crystal geometry, readout conditions and wrapping conditions, it was found that an optimum light output can only be achieved through a careful selection of highly reflective material along with high-transmittance optical adhesive used to bond the reflector. Decreasing the adhesive thickness was also found to have a positive outcome in most explored configurations, however to a much lesser extent. Suboptimal reflectivity and adhesive transmittance also lead to an asymmetric light output distribution dependent on the depth of interaction of the radiation, potentially degrading energy resolution. By identifying the factors causing the most significant scintillation light losses through a factorial design, the most promising detector configurations have been identified in the quest for optimal light collection from scintillators.

  16. YAP:Ce scintillator characteristics for neutron detection

    SciTech Connect

    Viererbl, L.; Klupak, V.; Vins, M.; Soltes, J.

    2015-07-01

    YAP:Ce (YAlO{sub 3}:Ce{sup +}, Yttrium Aluminum Perovskite, Ce{sup +} doped) crystals with appropriate converters seem like prospective scintillators for neutron detection. An important aspect for neutron detection with inorganic scintillators is the ability to discriminate neutron radiation from gamma radiation by pulse height of signals. For a detailed measurement of the aspect, a YAP:Ce crystal scintillator with lithium or hydrogen converters and a photomultiplier was used. A plutonium-beryllium neutron source and horizontal neutron channel beams of the LVR-15 research reactor were used as neutron sources. The measurement confirmed the possibility to use the YAP:Ce scintillator for neutron radiation detection. The degree of discrimination between neutron and gamma radiation for different detection configurations was studied. (authors)

  17. Influence of Depth of Interaction upon the Performance of Scintillator Detectors

    PubMed Central

    Brown, Mark S.; Gundacker, Stefan; Taylor, Alaric; Tummeltshammer, Clemens; Auffray, Etiennette; Lecoq, Paul; Papakonstantinou, Ioannis

    2014-01-01

    The uncertainty in time of particle detection within a scintillator detector, characterised by the coinci- dence time resolution (CTR), is explored with respect to the interaction position within the scintillator crystal itself. Electronic collimation between two scintillator detectors is utilised to determine the CTR with depth of interaction (DOI) for different materials, geometries and wrappings. Significantly, no rela- tionship between the CTR and DOI is observed within experimental error. Confinement of the interaction position is seen to degrade the CTR in long scintillator crystals by 10%. PMID:24875832

  18. Development of scintillation materials for medical imaging and other applications

    SciTech Connect

    Melcher, C. L.

    2013-02-05

    Scintillation materials that produce pulses of visible light in response to the absorption of energetic photons, neutrons, and charged particles, are widely used in various applications that require the detection of radiation. The discovery and development of new scintillators has accelerated in recent years, due in large part to their importance in medical imaging as well as in security and high energy physics applications. Better understanding of fundamental scintillation mechanisms as well as the roles played by defects and impurities have aided the development of new high performance scintillators for both gamma-ray and neutron detection. Although single crystals continue to dominate gamma-ray based imaging techniques, composite materials and transparent optical ceramics potentially offer advantages in terms of both synthesis processes and scintillation performance. A number of promising scintillator candidates have been identified during the last few years, and several are currently being actively developed for commercial production. Purification and control of raw materials and cost effective crystal growth processes can present significant challenges to the development of practical new scintillation materials.

  19. Segmented scintillation antineutrino detector

    DOEpatents

    Reyna, David

    2017-05-09

    The various technologies presented herein relate to incorporating a wavelength-shifting material in a scintillator to facilitate absorption of a first electromagnetic particle (e.g., a first photon) having a first wavelength and subsequent generation and emission of a second electromagnetic particle (e.g., a second photon) having a second wavelength. The second electromagnetic particle can be emitted isotropically, with a high probability that the direction of emission of the second electromagnetic particle is disparate to the direction of travel of the first electromagnetic particle (and according angle of incidence). Isotropic emission of the second electromagnetic particle enables the second electromagnetic particle to be retained in the scintillator owing to internal reflection. Accordingly, longer length scintillators can be constructed, and accordingly, the scintillator array has a greater area (and volume) over which to detect electromagnetic particles (e.g., antineutrinos) being emitted from a nuclear reaction.

  20. Scintillating pad detectors

    SciTech Connect

    Adams, D.; Baumbaugh, B.; Borcherding, F.

    1996-12-31

    We have been investigating the performance of scintillating pad detectors, individual small tiles of scintillator that are read out with wavelength-shifting fibers and visible light photon counters, for application in high luminosity colliding beam experiments such as the D0 Upgrade. Such structures could provide {open_quotes}pixel{close_quotes} type readout over large fiducial volumes for tracking, preshower detection and triggering.

  1. GAGG:ce single crystalline films: New perspective scintillators for electron detection in SEM.

    PubMed

    Bok, Jan; Lalinský, Ondřej; Hanuš, Martin; Onderišinová, Zuzana; Kelar, Jakub; Kučera, Miroslav

    2016-04-01

    Single crystal scintillators are frequently used for electron detection in scanning electron microscopy (SEM). We report gadolinium aluminum gallium garnet (GAGG:Ce) single crystalline films as a new perspective scintillators for the SEM. For the first time, the epitaxial garnet films were used in a practical application: the GAGG:Ce scintillator was incorporated into a SEM scintillation electron detector and it showed improved image quality. In order to prove the GAGG:Ce quality accurately, the scintillation properties were examined using electron beam excitation and compared with frequently used scintillators in the SEM. The results demonstrate excellent emission efficiency of the GAGG:Ce single crystalline films together with their very fast scintillation decay useful for demanding SEM applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Application of the Scintillation Detector on base of BrilLanCe Series Crystal in Neutral Particles Spectrometer for the Satellite Experiment ZINA-NT

    NASA Astrophysics Data System (ADS)

    Arkhangelskaja, Irene; Arkhangelsky, Andrey; Batischev, Alexey; Naumov, Pietr; Kondratyeva, Natalia

    In a condition of normal gravity, field-induced translational and rotational motions of solids are publically recognized for materials that contain spontaneous magnetic moments. It is believed that a high field above B = 10 T is necessary to induce such movements for ordinary diamagnetic material. Rotation and translation induced by low field of B = 0.5 T were recently reported on diamagnetic single-crystals of corundum [1], calcite, diamond, graphite and silver [2]. Here the crystals were released in microgravity produced by drop capsule(duration 4.5 s), and the motions took place in diffused gas medium (50Pa). In homogeneous field, crystal showed rotational oscillation with respect to field because of diamagnetic anisotropy energy. In a given field intensity, its period was determined by anisotropy of diamagnetic susceptibility. The crystal was ejected from field center by field-gradient force with significant terminal velocity. In a given field distribution, the velocity uniquely depended on intrinsic susceptibility of material. It is expected that the above two motions were independent to mass of sample. Necessity of clarifying magnetic properties of a single particle is increasing with the growing interest on nano-sized materials; data of susceptibility as well as its anisotropy are necessary for characterizing its property. However the values are difficult to obtain by conventional methods because of 2 factors; existence of a sample holder, and necessity of mass measurement. Susceptibility and its anisotropy of a single particle can be determined with high precision from above two motions in microgravity, because the methods are free of sample holder and mass measurement. Moreover, they are based on simple motional equations that consist of an inertia term and a magnetic term. In principle, magnetization is measured for limitlessly small sample, provided that the motions are observed. Attempt to obtain magnetization curve from the above-mentioned translation

  3. Ionospheric Scintillation Explorer (ISX)

    NASA Astrophysics Data System (ADS)

    Iuliano, J.; Bahcivan, H.

    2015-12-01

    NSF has recently selected Ionospheric Scintillation Explorer (ISX), a 3U Cubesat mission to explore the three-dimensional structure of scintillation-scale ionospheric irregularities associated with Equatorial Spread F (ESF). ISX is a collaborative effort between SRI International and Cal Poly. This project addresses the science question: To what distance along a flux tube does an irregularity of certain transverse-scale extend? It has been difficult to measure the magnetic field-alignment of scintillation-scale turbulent structures because of the difficulty of sampling a flux tube at multiple locations within a short time. This measurement is now possible due to the worldwide transition to DTV, which presents unique signals of opportunity for remote sensing of ionospheric irregularities from numerous vantage points. DTV spectra, in various formats, contain phase-stable, narrowband pilot carrier components that are transmitted simultaneously. A 4-channel radar receiver will simultaneously record up to 4 spatially separated transmissions from the ground. Correlations of amplitude and phase scintillation patterns corresponding to multiple points on the same flux tube will be a measure of the spatial extent of the structures along the magnetic field. A subset of geometries where two or more transmitters are aligned with the orbital path will be used to infer the temporal development of the structures. ISX has the following broad impact. Scintillation of space-based radio signals is a space weather problem that is intensively studied. ISX is a step toward a CubeSat constellation to monitor worldwide TEC variations and radio wave distortions on thousands of ionospheric paths. Furthermore, the rapid sampling along spacecraft orbits provides a unique dataset to deterministically reconstruct ionospheric irregularities at scintillation-scale resolution using diffraction radio tomography, a technique that enables prediction of scintillations at other radio frequencies, and

  4. Co-doping effects on luminescence and scintillation properties of Ce doped (Lu,Gd)3(Ga,Al)5O12 scintillator

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Hiroaki; Kamada, Kei; Kurosawa, Shunsuke; Pejchal, Jan; Shoji, Yasuhiro; Yokota, Yuui; Ohashi, Yuji; Yoshikawa, Akira

    2016-11-01

    Mg co-doping effects on scintillation properties of Ce:Lu1Gd2(Ga,Al)5O12 (LGGAG) were investigated. Mg 200 ppm co-doped Ce:LGGAG single crystals were prepared by micro pulling down method. Absorption and luminescence spectra were measured together with several other scintillation characteristics, namely the scintillation decay and light yield to reveal the effect of Mg co-doping. Ce4+ charge transfer absorption was observed below 300 nm in Mg,Ce:LGGAG which is in good agreement with previous reports. The scintillation decay times were accelerated by Mg co-doping.

  5. Single crystal growth of Ce:Gd3(Ga,Al)5O12 with various Mg concentration and their scintillation properties

    NASA Astrophysics Data System (ADS)

    Kamada, Kei; Shoji, Yasuhiro; Kochurikhin, Vladimir V.; Nagura, Aya; Okumura, Satoshi; Yamamoto, Seiichi.; Yeom, Jung Yeol; Kurosawa, Shunsuke; Pejchal, Jan; Yokota, Yuui; Ohashi, Yuji; Nikl, Martin; Yoshino, Masao; Yoshikawa, Akira

    2017-06-01

    1 in. diameter Mg 0.05, 0.1, 0.2, 0.5 mol% and Zr 0.015% co-doped Ce1%:GGAG crystals were grown by Cz method. Relationship between Mg concentration and absorption, luminescence, light output, decay time, timing resolution was investigated. Mg 0.2 mol% co-doped sample showed the fastest timing resolution of 165 ps among the Mg-co-doped samples.

  6. Defects Identification and Effects of Annealing on Lu2(1-x)Y2xSiO5 (LYSO) Single Crystals for Scintillation Application

    PubMed Central

    Blahuta, Samuel; Bessière, Aurélie; Viana, Bruno; Ouspenski, Vladimir; Mattmann, Eric; Lejay, Julien; Gourier, Didier

    2011-01-01

    The nature, properties and relative concentrations of electronic defects were investigated by Thermoluminescence (TL) in Lu2(1-x)Y2xSiO5 (LYSO) single crystals. Ce and Tb-doped single crystals, grown by the Czochralski technique (CZ), revealed similar traps in TL. LYSO:Ce single crystals were grown by the Floating-Zone technique (FZ) with increasing oxygen concentration in the growth atmosphere. TL intensity is strongly dependent on the oxygen content of the material, and oxygen vacancies are proven to be the main electronic defects in LYSO. The effects of oxidizing and reducing annealing post-treatment on these defects were investigated. While oxidizing treatments efficiently reduce the amount of electronic defects, reducing treatments increase the amount of existing traps. In a thermally assisted tunneling mechanism, the localization of oxygen vacancies around the dopant is discussed. They are shown to be in the close vicinity of the dopant, though not in first neighbor positions. PMID:28824138

  7. Evaluate Scintillation Response Over a Continuous Energy Region

    SciTech Connect

    Zhang, Yanwen; Elfman, Mikael; Milbrath, Brian D.; Weber, William J.

    2008-06-26

    A recently developed fast analysis technique utilizing a time of flight (TOF) telescope is demonstrated to obtain relevant quantitative data on material scintillation response to energetic He particles. With superior energy resolution and fast response of the TOF telescope, energy of individual particle before impinging on a scintillating crystal can be determined with a high counting rate, which allows quantitative study of material performance over a continuous energy range in a relatively short time. Scintillation performances in terms of light output, nonlinearity and energy resolution in bismuth germinate (BGO) and europium-doped calcium fluoride (CaF2:Eu) Crystals are demonstrated, and the corresponding energy resolution is compared with gamma-ray tests on the same crystals.

  8. Scintillator Measurements for SNO+

    NASA Astrophysics Data System (ADS)

    Kaptanoglu, Tanner; SNO+ Collaboration

    2016-03-01

    SNO+ is a neutrino detector located 2km underground in the SNOLAB facility with the primary goal of searching for neutrinoless double beta decay. The detector will be filled with a liquid scintillator target primarily composed of linear alkyl benzene (LAB). As charged particles travel through the detector the LAB produces scintillation light which is detected by almost ten thousand PMTs. The LAB is loaded with Te130, an isotope known to undergo double beta decay. Additionally, the LAB is mixed with an additional fluor and wavelength shifter to improve the light output and shift the light to a wavelength regime in which the PMTs are maximally efficient. The precise scintillator optics drastically affect the ultimate sensitivity of SNO+. I will present work being done to measure the optical properties of the SNO+ scintillator cocktail. The measured properties are used as input to a scintillation model that allows us to extrapolate to the SNO+ scale and ultimately predict the sensitivity of the experiment. Additionally, I will present measurements done to characterize the R5912 PMT, a candidate PMT for the second phase of SNO+ that provides better light collection, improved charge resolution, and a narrower spread in timing.

  9. New Structured Scintillators for Neutron Radiography

    NASA Astrophysics Data System (ADS)

    Nagarkar, V. V.; Ovechkina, E. E.; Bhandari, H. B.; Soundara-Pandian, L.; More, M. J.; Riedel, R. A.; Miller, S. R.

    minimized by lowering the film thickness and its neutron sensitivity can be maximized through the use of enriched Gd. The fabrication of micro-structured films of these materials using an evaporation technique permits the cost-effective volume synthesis of high-quality neutron scintillators over large areas (20 cm x 20 cm) in short time. In addition, the vapour deposition permits stoichiometry and dopant control not possible using conventional crystal growth.

  10. Scintillator plate calorimetry

    SciTech Connect

    Price, L.E.

    1990-01-01

    Calorimetry using scintillator plates or tiles alternated with sheets of (usually heavy) passive absorber has been proven over multiple generations of collider detectors. Recent detectors including UA1, CDF, and ZEUS have shown good results from such calorimeters. The advantages offered by scintillator calorimetry for the SSC environment, in particular, are speed (<10 nsec), excellent energy resolution, low noise, and ease of achieving compensation and hence linearity. On the negative side of the ledger can be placed the historical sensitivity of plastic scintillators to radiation damage, the possibility of nonuniform response because of light attenuation, and the presence of cracks for light collection via wavelength shifting plastic (traditionally in sheet form). This approach to calorimetry is being investigated for SSC use by a collaboration of Ames Laboratory/Iowa State University, Argonne National Laboratory, Bicron Corporation, Florida State University, Louisiana State University, University of Mississippi, Oak Ridge National Laboratory, Virginia Polytechnic Institute and State University, Westinghouse Electric Corporation, and University of Wisconsin.

  11. Scintillation spectrometry with HgI/sub 2/ as the photodetector

    SciTech Connect

    Iwanczyk, J.S.; Barton, J.B.; Dabrowski, A.J.; Kusmiss, J.H.; Szymczyk, W.M.; Huth, G.C.; Markakis, J.; Schnepple, W.F.; Lynn, R.

    1982-01-01

    A mercuric iodide (HgI/sub 2/) photodetector has been used to detect light pulses from gamma-ray and alpha-particle interactions in scintillators. The photocurrent response of an HgI/sub 2/ photodetector to light has been measured and found to be favorable for detecting light from most scintillators, which have their maximum emission between 300 and 500 nm. Energy spectra for alpha particles or gamma-rays from combinations of an HgI/sub 2/ photodetector with various scintillators are presented. The energy resolution of the photopeak from annihilation gamma-rays is 19% with a CsI(Tl) crystal and 24% with a BGO crystal. Fabrication of HgI/sub 2/ photodetectors and their optical coupling to a scintillator crystal are described. The advantages of this new solid-state radiation detector compared to the combination of scintillator and PMT, and some proposed applications, are discussed.

  12. On the influence of crystal structure on the electromagnetic shower development in the lead tungstate crystals

    NASA Astrophysics Data System (ADS)

    Baryshevsky, V. G.; Haurylavets, V. V.; Korjik, M. V.; Lobko, A. S.; Mechinsky, V. A.; Sytov, A. I.; Tikhomirov, V. V.; Uglov, V. V.

    2017-07-01

    The development of high-energy electromagnetic showers in long oriented lead tungstate crystals, accelerated by the effects induced by the strong field of atomic strings, is simulated for the first time. For that the characteristics of pair production and gamma-radiation by electrons or positrons were first simulated by the direct application of Baier-Katkov formulae in a thin PWO crystal to derive the scaling coefficients of the corresponding Bethe-Heitler cross sections to be incorporated into GEANT4 for the simulation of the electromagnetic shower development in a long crystal. Simulation results demonstrate the significant influence of the crystal structure on the e± and gamma-quanta registration processes in the existing homogeneous electromagnetic calorimeters and gamma-telescopes as well as wide possibilities of improving their performance in future developments.

  13. Chloride, bromide and iodide scintillators with europium

    DOEpatents

    Zhuravleva, Mariya; Yang, Kan

    2016-09-27

    A halide scintillator material is disclosed where the halide may comprise chloride, bromide or iodide. The material is single-crystalline and has a composition of the general formula ABX.sub.3 where A is an alkali, B is an alkali earth and X is a halide which general composition was investigated. In particular, crystals of the formula ACa.sub.1-yEu.sub.yI.sub.3 where A=K, Rb and Cs were formed as well as crystals of the formula CsA.sub.1-yEu.sub.yX.sub.3 (where A=Ca, Sr, Ba, or a combination thereof and X=Cl, Br or I or a combination thereof) with divalent Europium doping where 0.ltoreq.y.ltoreq.1, and more particularly Eu doping has been studied at one to ten mol %. The disclosed scintillator materials are suitable for making scintillation detectors used in applications such as medical imaging and homeland security.

  14. Scintillator Waveguide For Sensing Radiation

    DOEpatents

    Bliss, Mary; Craig, Richard A.; Reeder; Paul L.

    2003-04-22

    The present invention is an apparatus for detecting ionizing radiation, having: a waveguide having a first end and a second end, the waveguide formed of a scintillator material wherein the therapeutic ionizing radiation isotropically generates scintillation light signals within the waveguide. This apparatus provides a measure of radiation dose. The apparatus may be modified to permit making a measure of location of radiation dose. Specifically, the scintillation material is segmented into a plurality of segments; and a connecting cable for each of the plurality of segments is used for conducting scintillation signals to a scintillation detector.

  15. Scintillator requirements for medical imaging

    SciTech Connect

    Moses, William W.

    1999-09-01

    Scintillating materials are used in a variety of medical imaging devices. This paper presents a description of four medical imaging modalities that make extensive use of scintillators: planar x-ray imaging, x-ray computed tomography (x-ray CT), SPECT (single photon emission computed tomography) and PET (positron emission tomography). The discussion concentrates on a description of the underlying physical principles by which the four modalities operate. The scintillator requirements for these systems are enumerated and the compromises that are made in order to maximize imaging performance utilizing existing scintillating materials are discussed, as is the potential for improving imaging performance by improving scintillator properties.

  16. Polysiloxane scintillator composition

    DOEpatents

    Walker, James K.

    1992-01-01

    A plastic scintillator useful for detecting ionizing radiation comprising a matrix which comprises an optically transparent polysiloxane having incorporated therein at least one ionizing radiation-hard fluor capable of converting electromagnetic energy produced in the polysiloxane upon absorption of ionizing radiation to detectable light.

  17. Polysiloxane scintillator composition

    DOEpatents

    Walker, J.K.

    1992-05-05

    A plastic scintillator useful for detecting ionizing radiation comprising a matrix which comprises an optically transparent polysiloxane having incorporated therein at least one ionizing radiation-hard fluor capable of converting electromagnetic energy produced in the polysiloxane upon absorption of ionizing radiation to detectable light.

  18. Boron loaded scintillator

    DOEpatents

    Bell, Zane William [Oak Ridge, TN; Brown, Gilbert Morris [Knoxville, TN; Maya, Leon [Knoxville, TN; Sloop, Jr., Frederick Victor; Sloop, Jr., Frederick Victor [Oak Ridge, TN

    2009-10-20

    A scintillating composition for detecting neutrons and other radiation comprises a phenyl containing silicone rubber with carborane units and at least one phosphor molecule. The carbonate units can either be a carborane molecule dispersed in the rubber with the aid of a compatibilization agent or can be covalently bound to the silicone.

  19. An equatorial scintillation model

    NASA Astrophysics Data System (ADS)

    Fremouw, E. J.; Robins, R. E.

    1985-09-01

    Radiowave scintillation in the presence of natural and/or high altitude nuclear disturbances has the potential to disrupt numerous transionospheric radio and radar systems. This report develops a model characterizing the plasma density irregularities that produce scintillation in the naturally disturbed equatorial F layer. The model has been incorporated into Program WBMOD along with subroutines for computing both link geometry and scintillation indices, the latter by means of phase screen diffraction theory. The model is based on similarly extensive analysis of Wideband data from two equatorial stations. It describes irregularities at an effective height of 350 km that are isotropic across the geomagnetic field and elongated by a factor of 50 along the field and whose one dimensional spatial power spectrum obeys a single regime power law with a (negative) spectral index of 1.5. The height-integrated spectral strength of the irregularities is modeled as a function of solar epoch (sunspot number), the angle between the sunset terminator and the geomagnetic field line through the equatorial F layer point in question (a measure of seasonal and longitudinal variation), time after E-layer sunset on that field line, and the F-layer magnetic apex latitude of the point. The report also highlights a factor missing from complete characterization of the joint seasonal/longitudinal variation of scintillation, thought to depend upon thermospheric neutral winds.

  20. Quenching equation for scintillation

    NASA Astrophysics Data System (ADS)

    Kato, Takahisa

    1980-06-01

    A mathematical expression is postulated showing the relationship between counting rate and quenching agent concentration in a liquid scintillation solution. The expression is more suited to a wider range of quenching agent concentrations than the Stern-Volmer equation. An estimation of the quenched correction is demonstrated using the expression.

  1. Development of High-Resolution Scintillator Systems

    SciTech Connect

    Larry A. Franks; Warnick J. Kernan

    2007-09-01

    Mercuric iodide (HgI2) is a well known material for the direct detection of gamma-rays; however, the largest volume achievable is limited by the thickness of the detector which needs to be a small fraction of the average trapping length for electrons. We report results of using HgI2 crystals to fabricate photocells used in the readout of scintillators. The optical spectral response and efficiency of these photocells were measured and will be reported. Nuclear response from an HgI2 photocell that was optically matched to a cerium-activated scintillator is presented and discussed. Further improvements can be expected by optimizing the transparent contact technology.

  2. Transparent Ceramic Scintillator Fabrication, Properties and Applications

    SciTech Connect

    Cherepy, N J; Kuntz, J D; Roberts, J J; Hurst, T A; Drury, O B; Sanner, R D; Tillotson, T M; Payne, S A

    2008-08-24

    Transparent ceramics offer an alternative to single crystals for scintillator applications such as gamma ray spectroscopy and radiography. We have developed a versatile, scaleable fabrication method, using Flame Spray Pyrolysis (FSP) to produce feedstock which is readily converted into phase-pure transparent ceramics. We measure integral light yields in excess of 80,000 Ph/MeV with Cerium-doped Garnets, and excellent optical quality. Avalanche photodiode readout of Garnets provides resolution near 6%. For radiography applications, Lutetium Oxide offers a high performance metric and is formable by ceramics processing. Scatter in transparent ceramics due to secondary phases is the principal limitation to optical quality, and afterglow issues that affect the scintillation performance are presently being addressed.

  3. Scintillation Properties of Eu2+-Activated Barium Fluoroiodide

    SciTech Connect

    Gundiah, Gautam; Bourret-Courchesne, Edith; Bizarri, Gregory; Hanrahan, Stephen M.; Chaudhry, Anurag; Canning, Andrew; Moses, William W.; Derenzo, Stephen E.

    2009-11-18

    The scintillation properties of powders and single-crystals of BaFI doped with Eu2+ are presented. Single crystals were grown by the vertical Bridgman technique. Under optical and X-ray excitation, the samples exhibit a narrow E2+ 5d-4f transition emission centered at 405 nm. The scintillation light output is estimated to be 55,000+-5,000 photons/MeV at 662 keV with 85percent of the light decaying within 600 ns. An energyresolution of 8.5percent full width at half maximum (FWHM) has been achieved using this scintillator for 662 keV excitation (137Cs source) at room temperature.

  4. Proton-induced radioactivity in NaI (Tl) scintillation detectors

    NASA Technical Reports Server (NTRS)

    Fishman, G. J.

    1977-01-01

    Radioactivity induced by protons in sodium iodide scintillation crystals were calculated and directly measured. These data are useful in determining trapped radiation and cosmic-ray induced, background-counting rates in spaceborne detectors.

  5. Ca2+-Doped CeBr3 Scintillating Materials

    SciTech Connect

    Guss, Paul; Foster, Michael E.; Wong, Bryan M.; Doty, F. Patrick; Shah, Kanai; Squillante, Michael R.; Shirwadkar, Urmila; Hawrami, Rastgo; Tower, Josh; Yuan, Ding

    2014-01-01

    Despite the outstanding scintillation performance characteristics of cerium tribromide (CeBr3) and cerium-activated lanthanum tribromide, their commercial availability and application are limited due to the difficulties of growing large, crack-free single crystals from these fragile materials. This investigation employed aliovalent doping to increase crystal strength while maintaining the optical properties of the crystal. One divalent dopant (Ca2+) was used as a dopant to strengthen CeBr3 without negatively impacting scintillation performance. Ingots containing nominal concentrations of 1.9% of the Ca2+ dopant were grown. Preliminary scintillation measurements are presented for this aliovalently doped scintillator. Ca2+-doped CeBr3 exhibited little or no change in the peak fluorescence emission for 371 nm optical excitation for CeBr3. The structural, electronic, and optical properties of CeBr3 crystals were studied using the density functional theory within the generalized gradient approximation. The calculated lattice parameters are in good agreement with the experimental data. The energy band structures and density of states were obtained. The optical properties of CeBr3, including the dielectric function, were calculated.

  6. Composite scintillator screen

    DOEpatents

    Zeman, Herbert D.

    1994-01-01

    A scintillator screen for an X-ray system includes a substrate of low-Z material and bodies of a high-Z material embedded within the substrate. By preselecting the size of the bodies embedded within the substrate, the spacial separation of the bodies and the thickness of the screen, the sensitivity of the screen to X-rays within a predetermined energy range can be predicted.

  7. An Equatorial Scintillation Model

    DTIC Science & Technology

    1985-09-30

    been incor- porated into Program WBMOD along with subroutines for computing both link geometry and scintillation indices, the latter by means of...phase4screen diffraction theory. , Earlier versions of WBMOD , which are operational at USAF Global Weather Central and at several other user locations...which has been incorporated in WBMOD Version 8DI, is based on similarly extensive analysis of Wideband data from two equatorial stations. It describes

  8. Counterintuitive MCNPX Results for Scintillator Surface Roughness Effect

    SciTech Connect

    Yuan, Ding; Guss, Paul

    2012-10-01

    We performed a number of comparative MCNPX simulations of gamma energy depositions of scintillation crystals with smooth and rough surfaces. In the study, nine surface patterns (8 micro-roughness + 1 smooth) were coupled with eight common scintillation crystals for a total of 72 possible combinations. Although this was a preliminary study, the outcome was counterintuitive; results generally favored surfaces with micro-roughness over a conventional smooth surface as measured in terms of average energy depositions. The advantage gained through surface roughness is less significant for CdSe and LaCl3, but is most significant for the common NaI and the glass-like SiO2 scintillators. Based on the results of the 64 rough-surface coupled MCNPX simulations, 57 of the 64 (~89%) simulations showed some improvement in energy deposition. The mean improvement in energy deposition was 2.52%. The maximum improvement was about 8.75%, which was achieved when roughening the surface of a SiO2 scintillator using a micro cutting pattern. Further, for a conventional NaI scintillator, MCNPX results suggest that any roughness pattern would improve the energy deposition, with an average improvement of 3.83%. Although the likely causes remain unclear, we intend to focus on presenting simulation results instead of offering a sound explanation of the underlying physics.

  9. New scintillator and waveshifter materials

    NASA Astrophysics Data System (ADS)

    Zheng, H.; Baumbaugh, B.; Gerig, A.; Hurlbut, C.; Kauffman, J.; Marchant, J.; Pla-Dalmau, A.; Reynolds, K.; Ruchti, R.; Warchol, J.; Wayne, M.

    1998-11-01

    Experimental applications requiring fast timing and/or high efficiency position and energy measurements typically use scintillation materials. Scintillators utilized for triggering, tracking, and calorimetry in colliding beam detectors are vulnerable to the high radiation fields associated with such experiments. We have begun an investigation of several fluorescent dyes which might lead to fast, efficient, and radiation resistant scintillators. Preliminary results of spectral analysis and efficiency are presented.

  10. Scintillators with potential to supersede lanthanum bromide

    SciTech Connect

    Cherepy, Nerine; Payne, Steven; Aszatlos, Steve; Hull, Giulia; Kuntz, J.; Niedermayr, Tom; Pimputkar, S.; Roberts, J.; Sanner, R.; Tillotson, T.; van Loef, Edger; Wilson, Cody; Shah, Kanai; Roy, U.; Hawrami, R.; Burger, Arnold; Boatner, Lynn; Choong, Woon-Seng; Moses, William

    2009-06-01

    New scintillators for high-resolution gamma ray spectroscopy have been identified, grown and characterized. Our development efforts have focused on two classes of high light yield materials: Europium-doped alkaline earth halides and Cerium-doped garnets. Of the halide single crystals we have grown by the Bridgman method - SrI{sub 2}, CaI{sub 2}, SrBr{sub 2}, BaI{sub 2} and BaBr{sub 2} - SrI{sub 2} is the most promising. SrI{sub 2}(Eu) emits into the Eu{sup 2+} band, centered at 435 nm, with a decay time of 1.2 {micro}s and a light yield of up to 115,000 photons/MeV. It offers energy resolution better than 3% FWHM at 662 keV, and exhibits excellent light yield proportionality. Transparent ceramics fabrication allows production of Gadolinium- and Terbium-based garnets which are not growable by melt techniques due to phase instabilities. While scintillation light yields of Cerium-doped ceramic garnets are high, light yield non-proportionality and slow decay components appear to limit their prospects for high energy resolution. We are developing an understanding of the mechanisms underlying energy dependent scintillation light yield non-proportionality and how it affects energy resolution. We have also identified aspects of optical design that can be optimized to enhance energy resolution.

  11. Cerium fluoride, a new fast, heavy scintillator

    SciTech Connect

    Moses, W.W.; Derenzo, S.E.

    1988-11-01

    We describe the scintillation properties of Cerium Fluoride (CeF/sub 3/), a newly discovered, heavy (6.16 g/cm/sup 3/), inorganic scintillator. Its fluorescence decay lifetime, measured with the delayed coincidence method, is described by a single exponential with a 27 /+-/ ns time constant. The emission spectrum peaks at a wavelength of 340 nm, and drops to less than 10% of its peak value at 315 nm and 460 nm. When a 1 cm optical quality cube of CeF/sub 3/ is excited with 511 keV photons, a photopeak with a 20% full width at half maximum is observed at approximately half the light output of a Bismuth Germanate (BGO) crystal with similar geometry. We also present measurements of the decay time and light output of CeF/sub 3/ doped with three rare-earth elements (Dy, Er, and Pr). The short fluorescence lifetime, high density, and reasonable light output of this new scintillator suggest that it would be useful for applications where high counting rates, good stopping power, and nanosecond timing are important, such as medical imaging and nuclear science. 5 refs., 6 figs., 1 tab.

  12. Pulse shape analysis with scintillating bolometers

    NASA Astrophysics Data System (ADS)

    Gironi, L.

    2013-08-01

    Rare event searches impose strict requirements to the detectors such as an excellent energy resolution, a high detection efficiency and a very low background level. The bolometric technique has already proven to be very promising in this field. Among the features on which it is possible to further act to improve the detection sensitivity, the radioactive background reduction covers a primary role. This request can be satisfied through the possibility to identify the nature of the interacting particle. However, up to now, this opportunity can be fulfilled only with a double readout (e.g. heat and scintillation light). This double readout could greatly complicate the assembly of a huge, multi-detector array. The possibility to recognize the interacting particle through the shape of the thermal pulse is therefore a very interesting opportunity. Detailed analysis of the signal time development in macro-bolometers composed by scintillating crystals showed that it is possible to distinguish between β / γ and α particle interaction (i.e. the main source of background for 0 νDBD experiments based on the bolometric technique). Results of pulse shape analysis of signals from several bolometers with absorbers of different compositions (CaMoO4, ZnMoO4, ZnSe) are presented and the pulse shape discrimination capability of such detectors is discussed. An explanation of this behavior, based on the energy partition in the heat and scintillation channels, is also presented.

  13. Scintillating bolometers for Double Beta Decay search

    NASA Astrophysics Data System (ADS)

    Gironi, L.

    2010-05-01

    In the field of Double Beta Decay (DBD) searches, the use of high resolution detectors in which background can be actively discriminated is very appealing. Scintillating bolometers containing a Double Beta Decay emitter can largely fulfill this very interesting possibility. In this paper we present the latest results obtained with CdWO4 and CaMoO4 crystals. Moreover we report, for the first time, a very interesting feature of CaMoO4 bolometers: the possibility to discriminate β-γ events from those induced by α particles thanks to different thermal pulse shape.

  14. Neutron crosstalk between liquid scintillators

    SciTech Connect

    Verbeke, J. M.; Prasad, M. K.; Snyderman, N. J.

    2015-05-01

    We propose a method to quantify the fractions of neutrons scattering between liquid scintillators. Using a spontaneous fission source, this method can be utilized to quickly characterize an array of liquid scintillators in terms of crosstalk. The point model theory due to Feynman is corrected to account for these multiple scatterings. Using spectral information measured by the liquid scintillators, fractions of multiple scattering can be estimated, and mass reconstruction of fissile materials under investigation can be improved. Monte Carlo simulations of mono-energetic neutron sources were performed to estimate neutron crosstalk. A californium source in an array of liquid scintillators was modeled to illustrate the improvement of the mass reconstruction.

  15. Neutron crosstalk between liquid scintillators

    NASA Astrophysics Data System (ADS)

    Verbeke, J. M.; Prasad, M. K.; Snyderman, N. J.

    2015-09-01

    A method is proposed to quantify the fractions of neutrons scattering between liquid scintillators. Using a spontaneous fission source, this method can be utilized to quickly characterize an array of liquid scintillators in terms of crosstalk. The point model theory due to Feynman is corrected to account for these multiple scatterings. Using spectral information measured by the liquid scintillators, fractions of multiple scattering can be estimated, and mass reconstruction of fissile materials under investigation can be improved. Monte Carlo simulations of mono-energetic neutron sources were performed to estimate neutron crosstalk. A californium source in an array of liquid scintillators was modeled to illustrate the improvement of the mass reconstruction.

  16. PLASTIC SCINTILLATOR FOR RADIATION DOSIMETRY.

    PubMed

    Kim, Yewon; Yoo, Hyunjun; Kim, Chankyu; Lim, Kyung Taek; Moon, Myungkook; Kim, Jongyul; Cho, Gyuseong

    2016-09-01

    Inorganic scintillators, composed of high-atomic-number materials such as the CsI(Tl) scintillator, are commonly used in commercially available a silicon diode and a scintillator embedded indirect-type electronic personal dosimeters because the light yield of the inorganic scintillator is higher than that of an organic scintillator. However, when it comes to tissue-equivalent dose measurements, a plastic scintillator such as polyvinyl toluene (PVT) is a more appropriate material than an inorganic scintillator because of the mass energy absorption coefficient. To verify the difference in the absorbed doses for each scintillator, absorbed doses from the energy spectrum and the calculated absorbed dose were compared. From the results, the absorbed dose of the plastic scintillator was almost the same as that of the tissue for the overall photon energy. However, in the case of CsI, it was similar to that of the tissue only for a photon energy from 500 to 4000 keV. Thus, the values and tendency of the mass energy absorption coefficient of the PVT are much more similar to those of human tissue than those of the CsI. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  17. New Cerium-Based Metal-Organic Scintillators for Radiation Detection

    SciTech Connect

    Boatner, Lynn A; Neal, John S; Ramey, Joanne Oxendine; Chakoumakos, Bryan C; Custelcean, Radu; Van Loef, Edgar; Markosyan, G

    2013-01-01

    We have previously shown that a new class of scintillating materials can be developed based on the synthesis and crystal growth of rare-earth metal-organic compounds. The first scintillator of this type consisted of single crystals of CeCl3(CH3OH)4 that were grown from a methanol solution. These crystals were shown to be applicable to both gamma-ray and fast neutron detection. Subsequently, metal-organic scintillators consisting of the compound LaBr3(CH3OH)4 activated with varying levels of Ce3+ and of CeBr3(CH3OH)4 were grown in single crystal form. We have now extended the development of this new class of scintillators to more complex organic components by reacting rare-earth halides such as CeCl3 or CeBr3 with different isomers of propanol and butanol including 1-propanol, isobutanol, n-butanol, and tert-butanol. The reaction of CeCl3 or CeBr3 with these organics results in the formation of new and relatively complex molecular crystals whose structures were determined using single-crystal X-ray diffraction. These new metal-organic scintillating materials were grown in single crystal form from solution, and their scintillation characteristics have been investigated using X-ray-excited luminescence plus energy spectra obtained with gamma-ray and alpha-particle sources. If the reactions between the inorganic and organic components are not carried out under very dry and highly controlled conditions, molecular structures can be formed that incorporate waters of hydration. The present observation of scintillation in these hydrated rare-earth metal-organic compounds is apparently an original finding, since we are not aware of any previous reports of scintillation being observed in a material that incorporates waters of hydration

  18. The First Tests of a Large-Area Light Detector Equipped with Metallic Magnetic Calorimeters for Scintillating Bolometers for the LUMINEU Neutrinoless Double Beta Decay Search

    NASA Astrophysics Data System (ADS)

    Gray, D.; Enss, C.; Fleischmann, A.; Gastaldo, L.; Hassel, C.; Hengstler, D.; Kempf, S.; Loidl, M.; Navick, X. F.; Rodrigues, M.

    2016-08-01

    Future rare-event searches using scintillating crystals need very low background levels for high sensitivity; however, unresolved pile-up can limit this. We present the design and fabrication of large-area photon detectors based on metallic magnetic calorimeters (MMCs), optimized for fast rise times to resolve close pile-up. The first prototypes have been characterized using Fe-55 X-rays and ZnMoO4 crystal scintillation light. A fast intrinsic rise time of 25-30 \\upmu s has been measured and has been compared to the 250 \\upmu s scintillation light pulse rise time constant. The difference indicates that the scintillation process limits the light pulse rise time. The fast rise time allows for a reduction of background due to close pile-up events as well as the study of the inherent crystal scintillation process. MMC-based photon detectors are shown to be a promising tool for scintillating crystal based rare event searches.

  19. SU-C-201-01: Investigation of the Effects of Scintillator Surface Treatment On Light Output Measurements with SiPM Detectors

    SciTech Connect

    Valenciaga, Y; Prout, D; Chatziioannou, A

    2015-06-15

    Purpose: To examine the effect of different scintillator surface treatments (BGO crystals) on the fraction of scintillation photons that exit the crystal and reach the photodetector (SiPM). Methods: Positron Emission Tomography is based on the detection of light that exits scintillator crystals, after annihilation photons deposit energy inside these crystals. A considerable fraction of the scintillation light gets trapped or absorbed after going through multiple internal reflections on the interfaces surrounding the crystals. BGO scintillator crystals generate considerably less scintillation light than crystals made of LSO and its variants. Therefore, it is crucial that the small amount of light produced by BGO exits towards the light detector. The surface treatment of scintillator crystals is among the factors affecting the ability of scintillation light to reach the detectors. In this study, we analyze the effect of different crystal surface treatments on the fraction of scintillation light that is detected by the solid state photodetector (SiPM), once energy is deposited inside a BGO crystal. Simulations were performed by a Monte Carlo based software named GATE, and validated by measurements from individual BGO crystals coupled to Philips digital-SiPM sensor (DPC-3200). Results: The results showed an increment in light collection of about 4 percent when only the exit face of the BGO crystal, is unpolished; compared to when all the faces are polished. However, leaving several faces unpolished caused a reduction of at least 10 percent of light output when the interaction occurs as far from the exit face of the crystal as possible compared to when it occurs very close to the exit face. Conclusion: This work demonstrates the advantages on light collection from leaving unpolished the exit face of BGO crystals. The configuration with best light output will be used to obtain flood images from BGO crystal arrays coupled to SiPM sensors.

  20. Characterization of a SrF2 Scintillating Bolometer

    NASA Astrophysics Data System (ADS)

    Ginestra, C.; Coron, N.; García, E.; de Marcillac, P.; Martínez, M.; Ortigoza, Y.; Redon, T.; Torres, L.

    2012-06-01

    We present the analysis of the data obtained with a 53 g SrF2 scintillating bolometer operated at 20 mK. We have analyzed its heat and light response (time constants, linearity and energy resolution) and measured its scintillation relative efficiency factor for different particles (alpha, beta/gamma and neutrons). We have studied the spatial uniformity of the light output profiting from its internal contamination. The light amplitude of alphas from the delayed coincidence 224Ra→220Rn→216Po (emitted from the same crystal position) shows a positive correlation, evidence of a non-uniformity that worsens the light signal energy resolution by more than 50%.

  1. New Scintillator Materials (K2CeBr5) and (Cs2CeBr5)

    NASA Technical Reports Server (NTRS)

    Hawrami, R.; Volz, M. P.; Batra, A. K.; Aggarwal, M. D.; Roy, U. N.; Groza, M.; Burger, A.; Cherepy, Nerine; Niedermayr, Thomas; Payne, Stephen A.

    2008-01-01

    Cesium cerium bromide (Cs2CeBr5) and potassium cerium bromide (K2CeBr5) are new scintillator materials for X-ray and gamma ray detector applications. Recently halide scintillator materials, such as Ce doped lanthanum bromide has been proved to be very important material for the same purpose. These materials are highly hygroscopic; a search for high light yield non-hygroscopic materials was highly desirable to advance the scintillator technology. In this paper, we are reporting the crystal growth of novel scintillator materials, cesium cerium bromide (Cs2CeBr5) and potassium cerium bromide (K2CeBr5). Crystals were successfully grown from the melt using the vertical Bridgman-Stockbarger technique, in a comparison with the high performance LaBr3 or LaCl3 crystals, cerium based alkali halides crystals, (Cs2CeBr5) and (K2CeBr5) have similar scintillation properties, while being much less hygroscopic. Furthermore, cesium based compounds will not suffer from the self-activity present in potassium and lanthanum compounds. However the Cs2CeBr5 crystals did not grow properly probably due to non-congruent melting or to some phase transition during cooling. Keywords." Scintillator materials; Ce3+; Energy resolution; Light yield; K2CeBr5

  2. New Scintillator Materials (K2CeBr5) and (Cs2CeBr5)

    NASA Technical Reports Server (NTRS)

    Hawrami, R.; Volz, M. P.; Batra, A. K.; Aggarwal, M. D.; Roy, U. N.; Groza, M.; Burger, A.; Cherepy, Nerine; Niedermayr, Thomas; Payne, Stephen A.

    2008-01-01

    Cesium cerium bromide (Cs2CeBr5) and potassium cerium bromide (K2CeBr5) are new scintillator materials for X-ray and gamma ray detector applications. Recently halide scintillator materials, such as Ce doped lanthanum bromide has been proved to be very important material for the same purpose. These materials are highly hygroscopic; a search for high light yield non-hygroscopic materials was highly desirable to advance the scintillator technology. In this paper, we are reporting the crystal growth of novel scintillator materials, cesium cerium bromide (Cs2CeBr5) and potassium cerium bromide (K2CeBr5). Crystals were successfully grown from the melt using the vertical Bridgman-Stockbarger technique, in a comparison with the high performance LaBr3 or LaCl3 crystals, cerium based alkali halides crystals, (Cs2CeBr5) and (K2CeBr5) have similar scintillation properties, while being much less hygroscopic. Furthermore, cesium based compounds will not suffer from the self-activity present in potassium and lanthanum compounds. However the Cs2CeBr5 crystals did not grow properly probably due to non-congruent melting or to some phase transition during cooling. Keywords." Scintillator materials; Ce3+; Energy resolution; Light yield; K2CeBr5

  3. Using Thin Films to Screen Possible Scintillator Materials

    SciTech Connect

    Milbrath, Brian D.; Caggiano, Joseph A.; Engelhard, Mark H.; Joly, Alan G.; Matson, Dean W.; Nachimuthu, Ponnusamy; Olsen, Larry C.

    2009-06-30

    The discovery and optimization of new scintillators has traditionally been a rather slow process due to the difficulties of single crystal growth. This paper discusses the production of polycrystalline scintillator thin films (a few microns thick) which were tested in order to determine what characterizations could be made concerning a material’s ultimate potential as a scintillator prior to pursuing crystal growth. Thin films of CaF2(Eu), CeF3, and CeCl3, all known scintillators, were produced by vapor deposition. The hygroscopic CeCl3 was coated with multiple polymer-aluminum oxide bi-layers. Emission spectra peak wavelengths and decay times agreed with single crystal values. The films were too thin to measure gamma photopeaks, but using alpha energy deposition peaks, one could compare the relative photon yield/MeV between materials. The values obtained appear to give a relevant indication of a material’s light yield potential. The technique also appears useful for quickly determining the proper dopant amount for a given material.

  4. GPS Scintillation Analysis.

    DTIC Science & Technology

    2007-11-02

    Rev. 2-89) Prescribed by ANSI Std. Z39-1 298-102 TABLE OF CONTENTS 1. INTRODUCTION 1 2. GPS COMPARISON WITH ALL-SKY IMAGES OVER AGUA VERDE...Depletions from 1 October 1994 2 3. GPS data from Agua Verde, Chile on the night of 1 October 1994 3 4. PL-SCINDA display of GPS ionospheric...comparison of GPS measurements with GOES8 L-band scintillation data, are discussed. 2. GPS COMPARISON WITH ALL-SKY IMAGES OVER AGUA VERDE, CHILE As

  5. Scintillation detector for carbon-14

    NASA Technical Reports Server (NTRS)

    Knoll, G. F.; Rogers, W. L.

    1971-01-01

    Detector consists of plastic, cylindrical double-wall scintillation cell, which is filled with gas to be analyzed. Thin, inner cell wall is isolated optically from outer (guard) scintillator wall by evaporated-aluminum coating. Bonding technique provides mechanical support to cell wall when device is exposed to high temperatures.

  6. Hybrid scintillators for neutron discrimination

    DOEpatents

    Feng, Patrick L; Cordaro, Joseph G; Anstey, Mitchell R; Morales, Alfredo M

    2015-05-12

    A composition capable of producing a unique scintillation response to neutrons and gamma rays, comprising (i) at least one surfactant; (ii) a polar hydrogen-bonding solvent; and (iii) at least one luminophore. A method including combining at least one surfactant, a polar hydrogen-bonding solvent and at least one luminophore in a scintillation cell under vacuum or an inert atmosphere.

  7. Development of intrinsic IPT scintillator

    SciTech Connect

    Bross, A.D.

    1989-07-31

    We report on the development of a new polystyrene based plastic scintillator. Optical absorption, fluorescence and light output measurements are presented. Preliminary results of radiation damage effects are also given and compared to the effects on a commercial plastic scintillator, NE 110. 6 refs., 12 figs.

  8. Development of radiation hard scintillators

    NASA Astrophysics Data System (ADS)

    Markley, F.; Davidson, M.; Keller, J.; Foster, G.; Pla-Dalmau, A.; Harmon, J.; Biagtan, E.; Schueneman, G.; Senchishin, V.; Gustfason, H.

    1993-11-01

    The authors have demonstrated that the radiation stability of scintillators made from styrene polymer is very much improved by compounding with pentaphenyl trimethyl trisiloxane (DC 705 vacuum pump oil). The resulting scintillators are softer than desired, so they decided to make the scintillators directly from monomer where the base resin could be easily crosslinked to improve the mechanical properties. They can now demonstrate that scintillators made directly from the monomer, using both styrene and 4-methyl styrene, are also much more radiation resistant when modified with DC705 oil. In fact, they retain from 92% to 95% of their original light output after gamma irradiation to 10 Mrads in nitrogen with air annealing. When these scintillators made directly from monomer are compared with scintillators of the same composition made from polymer the latter have much higher light outputs. They commonly reach 83% while those made from monomer give only 50% to 60% relative to the reference, BC408. When oil modified scintillators using both p-terphenyl and tetra phenyl butadiene are compared with identical scintillators except that they use 3 hydroxy-flavone as the only luminophore the radiation stability is the same. However the 3HF system gives only 30% as much light as BC408 instead of 83% when both are measured with a green extended Phillips XP2081B phototube.

  9. Extruding plastic scintillator at Fermilab

    SciTech Connect

    Anna Pla-Dalmau; Alan D. Bross; Victor V. Rykalin

    2003-10-31

    An understanding of the costs involved in the production of plastic scintillators and the development of a less expensive material have become necessary with the prospects of building very large plastic scintillation detectors. Several factors contribute to the high cost of plastic scintillating sheets, but the principal reason is the labor-intensive nature of the manufacturing process. In order to significantly lower the costs, the current casting procedures had to be abandoned. Since polystyrene is widely used in the consumer industry, the logical path was to investigate the extrusion of commercial-grade polystyrene pellets with dopants to yield high quality plastic scintillator. This concept was tested and high quality extruded plastic scintillator was produced. The D0 and MINOS experiments are already using extruded scintillator strips in their detectors. An extrusion line has recently been installed at Fermilab in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new facility will serve to further develop and improve extruded plastic scintillator. This paper will discuss the characteristics of extruded plastic scintillator and its raw materials, the different manufacturing techniques and the current R&D program at Fermilab.

  10. Development of radiation hard scintillators

    SciTech Connect

    Markley, F.; Davidson, M.; Keller, J.; Foster, G.; Pla-Dalmau, A.; Harmon, J.; Biagtan, E.; Schueneman, G.; Senchishin, V.; Gustfason, H.; Rivard, M.

    1993-11-01

    The authors have demonstrated that the radiation stability of scintillators made from styrene polymer is very much improved by compounding with pentaphenyltrimethyltrisiloxane (DC 705 vacuum pump oil). The resulting scintillators are softer than desired, so they decided to make the scintillators directly from monomer where the base resin could be easily crosslinked to improve the mechanical properties. They can now demonstrate that scintillators made directly from the monomer, using both styrene and 4-methyl styrene, are also much more radiation resistant when modified with DC705 oil. In fact, they retain from 92% to 95% of their original light output after gamma irradiation to 10 Mrads in nitrogen with air annealing. When these scintillators made directly from monomer are compared with scintillators of the same composition made from polymer the latter have much higher light outputs. They commonly reach 83% while those made form monomer give only 50% to 60% relative to the reference, BC408. When oil modified scintillators using both p-terphenyl and tetraphenylbutadiene are compared with identical scintillators except that they use 3 hydroxy-flavone as the only luminophore the radiation stability is the same. However the 3HF system gives only 30% as much light as BC408 instead of 83% when both are measured with a green extended Phillips XP2081B phototube.

  11. Efficiency of Scintillator Materials in the Energy Range 8.0-32.0 keV

    SciTech Connect

    Kinney, J H; Haupt, D L

    2002-07-01

    X-ray microtomography requires the measurement of x-ray attenuation along ray paths through a specimen, and on the inversion of these data to obtain a spatially resolved mapping of the microstructure of the specimen. To do this efficiently, two-dimensional array detectors are often used to measure the transmitted x-rays by capturing and recording each x-ray incident on the detector. The highest resolution CT instruments perform this by converting the incident x-rays to visible light, and then focusing this light onto a charge-coupled-device (CCD) detector. The light output of the scintillator (photons per incident x-ray), the numerical aperture of the optical lens system, and the quantum efficiency of the CCD govern the efficiency of the detection process. Several years earlier, our group performed an investigation aimed at determining the best scintillator material for high-resolution synchrotron CT. The selection criteria included light output in the 8-32 keV energy range, the spatial resolution of the scintillator, the wavelength of the scintillation radiation, and the stability and ease of polishing of the scintillator. A list of the scintillators that we considered, with the exceptions of the more recently developed glass scintillators, is provided in Table 1. Among these scintillators, we concluded that single crystal cadmium tungstate was optimum; we have used this material in all subsequent synchrotron CT systems. Since this original study, several doped-glass scintillators have become available. The LSO (Lu orthosilicates) scintillators, developed for PET scanning, show considerable light output at high energy (energies above 500 keV). Theoretically, the light output of these scintillators should be twice that of the cadmium tungstate. The purpose of this study was to determine the efficiency of two such scintillators (LSO:Yt and IQI-401 high density terbium activated glass) in the energy range from 8-32 keV.

  12. Transparent BaCl II:Eu 2+ glass-ceramic scintillator

    NASA Astrophysics Data System (ADS)

    Chen, Gang; Johnson, Jacqueline; Schweizer, Stefan; Woodford, John; Newman, Peter; MacFarlane, Douglas

    2006-03-01

    Scintillators are the backbone of high-energy radiation detection devices. Most scintillators are based on inorganic crystals that have applications in medical radiography, nuclear medicine, security inspection, dosimetry, and high-energy physics. In this paper, we present a new type of scintillator that is based on glass ceramics (composites of glasses and crystals). These scintillators are made from Eu 2+-activated fluorozirconate glasses that are co-doped with Ba 2+, La 3+, Al 3+, Na +, and Cl -. Subsequent heat treatment of the glasses forms BaCl II nano-crystals (10-20 nm in size) that are embedded in the glass matrix. The resulting scintillators are transparent, efficient, inexpensive to fabricate, and easy to scale up. The physical structure and x-ray imaging performance of these glass-ceramic scintillators are presented, and an application of these materials to micro-computed tomography is demonstrated. Our study suggests that these glass-ceramic scintillators have high potential for medical x-ray imaging.

  13. Scintillator based beta batteries

    NASA Astrophysics Data System (ADS)

    Rensing, Noa M.; Tiernan, Timothy C.; Shirwadkar, Urmila; O'Dougherty, Patrick; Freed, Sara; Hawrami, Rastgo; Squillante, Michael R.

    2013-05-01

    Some long-term, remote applications do not have access to conventional harvestable energy in the form of solar radiation (or other ambient light), wind, environmental vibration, or wave motion. Radiation Monitoring Devices, Inc. (RMD) is carrying out research to address the most challenging applications that need power for many months or years and which have undependable or no access to environmental energy. Radioisotopes are an attractive candidate for this energy source, as they can offer a very high energy density combined with a long lifetime. Both large scale nuclear power plants and radiothermal generators are based on converting nuclear energy to heat, but do not scale well to small sizes. Furthermore, thermo-mechanical power plants depend on moving parts, and RTG's suffer from low efficiency. To address the need for compact nuclear power devices, RMD is developing a novel beta battery, in which the beta emissions from a radioisotope are converted to visible light in a scintillator and then the visible light is converted to electrical power in a photodiode. By incorporating 90Sr into the scintillator SrI2 and coupling the material to a wavelength-matched solar cell, we will create a scalable, compact power source capable of supplying milliwatts to several watts of power over a period of up to 30 years. We will present the latest results of radiation damage studies and materials processing development efforts, and discuss how these factors interact to set the operating life and energy density of the device.

  14. DSB:Ce3+ scintillation glass for future

    NASA Astrophysics Data System (ADS)

    Auffray, E.; Akchurin, N.; Benaglia, A.; Borisevich, A.; Cowden, C.; Damgov, J.; Dormenev, V.; Dragoiu, C.; Dudero, P.; Korjik, M.; Kozlov, D.; Kunori, S.; Lecoq, P.; Lee, S. W.; Lucchini, M.; Mechinsky, V.; Pauwels, K.

    2015-02-01

    One of the main challenges for detectors at future high-energy collider experiments is the high precision measurement of hadron and jet energy and momentum. One possibility to achieve this is the dual-readout technique, which allows recording simultaneously scintillation and Cherenkov light in an active medium in order to extract the electromagnetic fraction of the total shower energy on an event- by-event basis. Making use of this approach in the high luminosity LHC, however, puts stringent requirements on the active materials in terms of radiation hardness. Consequently, the R&D carried out on suitable scintillating materials focuses on the detector performance as well as on radiation tolerance. Among the different scintillating materials under study, scintillating glasses can be a suitable solution due to their relatively simple and cost effective production. Recently a new type of inorganic scintillating glass: Cerium doped DSB has been developed by Radiation Instruments and New Components LLC in Minsk for oil logging industry. This material can be produced either in form of bulk or fiber shape with diameter 0.3-2mm and length up to 2000 mm. It is obtained by standard glass production technology at temperature 1400°C with successive thermal annealing treatment at relatively low temperature. The production of large quantities is relatively easy and the production costs are significantly lower compared to crystal fibers. Therefore, this material is considered as an alternative and complementary solution to crystal fibers in view of a production at industrial scale, as required for a large dual readout calorimeter. In this paper, the first results on optical, scintillation properties as well as the radiation damage behaviour obtained on different samples made with different raw materials and various cerium concentrations will be presented.

  15. Maximum likelihood positioning and energy correction for scintillation detectors.

    PubMed

    Lerche, Christoph W; Salomon, André; Goldschmidt, Benjamin; Lodomez, Sarah; Weissler, Björn; Solf, Torsten

    2016-02-21

    An algorithm for determining the crystal pixel and the gamma ray energy with scintillation detectors for PET is presented. The algorithm uses Likelihood Maximisation (ML) and therefore is inherently robust to missing data caused by defect or paralysed photo detector pixels. We tested the algorithm on a highly integrated MRI compatible small animal PET insert. The scintillation detector blocks of the PET gantry were built with the newly developed digital Silicon Photomultiplier (SiPM) technology from Philips Digital Photon Counting and LYSO pixel arrays with a pitch of 1 mm and length of 12 mm. Light sharing was used to readout the scintillation light from the 30 × 30 scintillator pixel array with an 8 × 8 SiPM array. For the performance evaluation of the proposed algorithm, we measured the scanner's spatial resolution, energy resolution, singles and prompt count rate performance, and image noise. These values were compared to corresponding values obtained with Center of Gravity (CoG) based positioning methods for different scintillation light trigger thresholds and also for different energy windows. While all positioning algorithms showed similar spatial resolution, a clear advantage for the ML method was observed when comparing the PET scanner's overall single and prompt detection efficiency, image noise, and energy resolution to the CoG based methods. Further, ML positioning reduces the dependence of image quality on scanner configuration parameters and was the only method that allowed achieving highest energy resolution, count rate performance and spatial resolution at the same time.

  16. High resolution scintillation spectroscopy with HgI/sub 2/ as the photodetector

    SciTech Connect

    Markakis, J.M.

    1987-01-01

    This report details the progress made in developing mercuric iodide photocells - in particular as the photodetector in scintillation spectrometers where photomultipliers are conventionally used. A spectrometer consisting of an HgI/sub 2/ photocell optically coupled with a CsI(Tl) scintillator gave a /sup 137/Cs (662 keV) resolution of 5.33% FWHM, the best /sup 137/Cs resolution reported to date using a scintillation spectrometer. Relative to photomultiplier tubes, solid state photodetectors are smaller, insensitive to magnetic fields, and have higher quantum efficiencies. HgI/sub 2/ photocells offer an unprecedented energy resolution for scintillation spectrometers and push closer to the resolution of scintillation crystals themselves.

  17. Radiation-resistant composite scintillators based on GSO and GPS grains

    NASA Astrophysics Data System (ADS)

    Boyarintsev, A. Yu.; Galunov, N. Z.; Gerasymov, Ia. V.; Karavaeva, N. L.; Krech, A. V.; Levchuk, L. G.; Popov, V. F.; Sidletskiy, O. Ts.; Sorokin, P. V.; Tarasenko, O. A.

    2017-01-01

    The effect of irradiation on the scintillation light output, optical transmittance, and luminescent spectra of composite scintillators based on grains of single crystals Gd2SiO5:Ce (GSO) and Gd2Si2O7:Ce (GPS) is studied. The dielectric gel Sylgard-184 is the base and the binder for the grains inside the composite scintillator. The paper presents and analyzes the results obtained for the scintillators exposed by 10 MeV electrons from the linear electron accelerator at room temperature. The exposure doses D≤250 Mrad. The dose rate is 0.2 or 1500 Mrad/h. The study has shown that the composite scintillators based on the grains of GSO and GPS are radiation-resistant over the range of the irradiation.

  18. Effect of host glass matrix on structural and optical behavior of glass-ceramic nanocomposite scintillators

    NASA Astrophysics Data System (ADS)

    Brooke Barta, M.; Nadler, Jason H.; Kang, Zhitao; Wagner, Brent K.; Rosson, Robert; Kahn, Bernd

    2013-12-01

    Composite scintillator systems have received increased attention in recent years due to their promise for merging the radioisotope discrimination capabilities of single crystal scintillators with the high throughput scanning capabilities of portal monitors. However, producing the high light yield required for good energy resolution has proven challenging as scintillation photons are often scattered by variations in refractive index and agglomerated scintillator crystals within the composite. This investigation sought to mitigate these common problems by using glass-ceramic nanocomposite materials systems in which nanoscale scintillating crystallites are precipitated in a controlled manner from a transparent glass matrix. Precipitating crystallites in situ precludes nanoparticle agglomeration, and limiting crystallite size to 50 nm or less mitigates the effect of refractive index mismatch between the crystals and host glass. Cerium-doped gadolinium bromide (GdBr3(Ce)) scintillating crystals were incorporated into sodium-aluminosilicate (NAS) and alumino-borosilicate (ABS) host glass matrices, and the resulting glass-ceramic structures and luminescence behavior were characterized. The as-cast glass from the ABS system displayed a highly ordered microstructure that produced the highest luminescence intensity (light yield) of the samples studied. However, heat treating to form the glass-ceramic precipitated rare-earth oxide crystallites rather than rare-earth halides. This degraded light yield relative to the unaged sample.

  19. Proton recoil scintillator neutron rem meter

    DOEpatents

    Olsher, Richard H.; Seagraves, David T.

    2003-01-01

    A neutron rem meter utilizing proton recoil and thermal neutron scintillators to provide neutron detection and dose measurement. In using both fast scintillators and a thermal neutron scintillator the meter provides a wide range of sensitivity, uniform directional response, and uniform dose response. The scintillators output light to a photomultiplier tube that produces an electrical signal to an external neutron counter.

  20. Liquid scintillator tiles for calorimetry

    NASA Astrophysics Data System (ADS)

    Amouzegar, M.; Belloni, A.; Bilki, B.; Calderon, J.; De Barbaro, P.; Eno, S. C.; Hatakeyama, K.; Hirschauer, J.; Jeng, G. Y.; Pastika, N. J.; Pedro, K.; Rumerio, Paolo; Samuel, J.; Sharp, E.; Shin, Y. H.; Tiras, E.; Vishnevskiy, D.; Wetzel, J.; Yang, Z.; Yao, Y.; Youn, S. W.

    2016-11-01

    Future experiments in high energy and nuclear physics may require large, inexpensive calorimeters that can continue to operate after receiving doses of 50 Mrad or more. The light output of liquid scintillators suffers little degradation under irradiation. However, many challenges exist before liquids can be used in sampling calorimetry, especially regarding developing a packaging that has sufficient efficiency and uniformity of light collection, as well as suitable mechanical properties. We present the results of a study of a scintillator tile based on the EJ-309 liquid scintillator using cosmic rays and test beam on the light collection efficiency and uniformity, and some preliminary results on radiation hardness.

  1. Liquid scintillator tiles for calorimetry

    SciTech Connect

    Amouzegar, M.; Belloni, A.; Bilki, B.; Calderon, J.; Barbaro, P. De; Eno, S. C.; Hatakeyama, K.; Hirschauer, J.; Jeng, G. Y.; Pastika, N. J.; Pedro, K.; Rumerio, Paolo; Samuel, J.; Sharp, E.; Shin, Y. H.; Tiras, E.; Vishnevskiy, D.; Wetzel, J.; Yang, Z.; Yao, Y.; Youn, S. W.

    2016-11-28

    Future experiments in high energy and nuclear physics may require large, inexpensive calorimeters that can continue to operate after receiving doses of 50 Mrad or more. Also, the light output of liquid scintillators suffers little degradation under irradiation. However, many challenges exist before liquids can be used in sampling calorimetry, especially regarding developing a packaging that has sufficient efficiency and uniformity of light collection, as well as suitable mechanical properties. We present the results of a study of a scintillator tile based on the EJ-309 liquid scintillator using cosmic rays and test beam on the light collection efficiency and uniformity, and some preliminary results on radiation hardness.

  2. High energy resolution plastic scintillator

    NASA Astrophysics Data System (ADS)

    van Loef, Edgar V.; Feng, Patrick; Markosyan, Gary; Shirwadkar, Urmila; Doty, Patrick; Shah, Kanai S.

    2016-09-01

    In this paper we present results on a novel tin-loaded plastic scintillator. We will show that this particular plastic scintillator has a light output similar to that of BGO, a fast scintillation decay (< 10 ns), exhibits good neutron/gamma PSD with a Figure-of-Merit of 1.3 at 2.5 MeVee cut-off energy, and excellent energy resolution of about 12% (FWHM) at 662 keV. Under X-ray excitation, the radioluminescence spectrum exhibits a broad band between 350 and 500 nm peaking at 420 nm which is well-matched to bialkali photomultiplier tubes and UV-enhanced photodiodes.

  3. Scintillator materials containing lanthanum fluorides

    DOEpatents

    Moses, William W.

    1991-01-01

    An improved radiation detector containing a crystalline mixture of LaF.sub.3 and CeF.sub.3 as the scintillator element is disclosed. Scintillators made with from 25% to 99.5% LaF.sub.3 and the remainder CeF.sub.3 have been found to provide a balance of good stopping power, high light yield and short decay constant that is equal to or superior to other known scintillator materials, and which may be processed from natural starting materials containing both rare earth elements. The radiation detectors disclosed are favorably suited for use in general purpose detection and in positron emission tomography.

  4. Ionospheric scintillation studies

    NASA Technical Reports Server (NTRS)

    Rino, C. L.; Freemouw, E. J.

    1973-01-01

    The diffracted field of a monochromatic plane wave was characterized by two complex correlation functions. For a Gaussian complex field, these quantities suffice to completely define the statistics of the field. Thus, one can in principle calculate the statistics of any measurable quantity in terms of the model parameters. The best data fits were achieved for intensity statistics derived under the Gaussian statistics hypothesis. The signal structure that achieved the best fit was nearly invariant with scintillation level and irregularity source (ionosphere or solar wind). It was characterized by the fact that more than 80% of the scattered signal power is in phase quadrature with the undeviated or coherent signal component. Thus, the Gaussian-statistics hypothesis is both convenient and accurate for channel modeling work.

  5. Drift scintillation meter

    NASA Astrophysics Data System (ADS)

    1984-03-01

    This is the final report for the subject contract under which The University of Texas at Dallas (UTD) built, tested and delivered an engineering model and three flight versions of the Drift Scintillation Meter (DSM) to the Air Force Geophysics Laboratory for flight on the Air Force DMSP satellites. The report is divided into three sections. Section 1 contains the instrument description and theory of operation. Section 2 contains a description of planned spacecraft-level instrument testing, stimulation requirements and instrument handling and safety. Section 3 contains an instrument interconnection diagram and a list of the schematics, drawings, parts lists and wiring lists that describe the as-built configuration of the instrument. This documentation is available in the R&D Equipment Information Reports that were submitted to AFGL after each instrument delivery.

  6. Lithium indium diselenide: A new scintillator for neutron imaging

    SciTech Connect

    Lukosi, Eric; Herrera, Elan; Hamm, Daniel; Lee, Kyung -Min; Wiggins, Brenden; Trtik, Pavel; Penumadu, Dayakar; Young, Stephen; Santodonato, Louis; Bilheux, Hassina; Burger, Arnold; Matei, Liviu; Stowe, Ashley C.

    2016-05-20

    Lithium indium diselenide, 6LiInSe2 or LISe, is a newly developed neutron detection material that shows both semiconducting and scintillating properties. The 24% atomic density of 6Li yields a thermal neutron mean free path of only 920 μm. This paper reports on the performance of LISe crystals in scintillation mode for its potential use as a converter screen for thermal/cold neutron imaging. The spatial resolution of LISe, determined using a 10% value of the Modulation Transfer Function (MTF), was found to not scale linearly with thickness. Crystals having a thickness of 450 μm or larger resulted in an average spatial resolution of 67 μm, and the thinner crystals exhibited an increase in spatial resolution down to the Nyquist frequency of the CCD. The highest measured spatial resolution of 198 μm thick LISe (27 μm) outperforms a commercial 50 μm thick ZnS(Cu):6LiF scintillation screen (100 μm) by more than a factor of three. For the thicknesses considered in this study, it has been found that the light yield of LISe did not scale with its thickness, suggesting the need for optimizing the synthesis to enhance the scintillation mechanism. Absorption measurements indicate that the 6Li concentration is uniform throughout the samples and its absorption efficiency as a function of thickness follows general nuclear theory, indicating that the variation in apparent brightness is likely due to a combination of particle escape, light transport, and activation of the scintillation mechanisms. As a result, the presence of 115In and its long-lived 116In activation product did not result in ghosting (memory of past neutron exposure), demonstrating potential for using LISe for imaging transient systems.

  7. Lithium indium diselenide: A new scintillator for neutron imaging

    NASA Astrophysics Data System (ADS)

    Lukosi, Eric; Herrera, Elan; Hamm, Daniel; Lee, Kyung-Min; Wiggins, Brenden; Trtik, Pavel; Penumadu, Dayakar; Young, Stephen; Santodonato, Louis; Bilheux, Hassina; Burger, Arnold; Matei, Liviu; Stowe, Ashley C.

    2016-09-01

    Lithium indium diselenide, 6LiInSe2 or LISe, is a newly developed neutron detection material that shows both semiconducting and scintillating properties. This paper reports on the performance of scintillating LISe crystals for its potential use as a converter screen for cold neutron imaging. The spatial resolution of LISe, determined using a 10% threshold of the Modulation Transfer Function (MTF), was found to not scale linearly with thickness. Crystals having a thickness of 450 μm or larger resulted in an average spatial resolution of 67 μm, and the thinner crystals exhibited an increase in spatial resolution down to the Nyquist frequency of the CCD. The highest measured spatial resolution of 198 μm thick LISe (27 μm) outperforms a commercial 50 μm thick ZnS(Cu):6LiF scintillation screen by more than a factor of three. For the LISe dimensions considered in this study, it was found that the light yield of LISe did not scale with its thickness. However, absorption measurements indicate that the 6Li concentration is uniform and the neutron absorption efficiency of LISe as a function of thickness follows general nuclear theory. This suggests that the differences in apparent brightness observed for the LISe samples investigated may be due to a combination of secondary charged particle escape, scintillation light transport in the bulk and across the LISe-air interface, and variations in the activation of the scintillation mechanism. Finally, it was found that the presence of 115In and its long-lived 116In activation product did not result in ghosting (memory of past neutron exposure), demonstrating potential of LISe for imaging transient systems.

  8. Lithium indium diselenide: A new scintillator for neutron imaging

    SciTech Connect

    Lukosi, Eric; Herrera, Elan; Hamm, Daniel; Lee, Kyung -Min; Wiggins, Brenden; Trtik, Pavel; Penumadu, Dayakar; Young, Stephen; Santodonato, Louis; Bilheux, Hassina; Burger, Arnold; Matei, Liviu; Stowe, Ashley C.

    2016-05-20

    Lithium indium diselenide, 6LiInSe2 or LISe, is a newly developed neutron detection material that shows both semiconducting and scintillating properties. The 24% atomic density of 6Li yields a thermal neutron mean free path of only 920 μm. This paper reports on the performance of LISe crystals in scintillation mode for its potential use as a converter screen for thermal/cold neutron imaging. The spatial resolution of LISe, determined using a 10% value of the Modulation Transfer Function (MTF), was found to not scale linearly with thickness. Crystals having a thickness of 450 μm or larger resulted in an average spatial resolution of 67 μm, and the thinner crystals exhibited an increase in spatial resolution down to the Nyquist frequency of the CCD. The highest measured spatial resolution of 198 μm thick LISe (27 μm) outperforms a commercial 50 μm thick ZnS(Cu):6LiF scintillation screen (100 μm) by more than a factor of three. For the thicknesses considered in this study, it has been found that the light yield of LISe did not scale with its thickness, suggesting the need for optimizing the synthesis to enhance the scintillation mechanism. Absorption measurements indicate that the 6Li concentration is uniform throughout the samples and its absorption efficiency as a function of thickness follows general nuclear theory, indicating that the variation in apparent brightness is likely due to a combination of particle escape, light transport, and activation of the scintillation mechanisms. As a result, the presence of 115In and its long-lived 116In activation product did not result in ghosting (memory of past neutron exposure), demonstrating potential for using LISe for imaging transient systems.

  9. Lithium indium diselenide: A new scintillator for neutron imaging

    DOE PAGES

    Lukosi, Eric; Herrera, Elan; Hamm, Daniel; ...

    2016-05-20

    Lithium indium diselenide, 6LiInSe2 or LISe, is a newly developed neutron detection material that shows both semiconducting and scintillating properties. The 24% atomic density of 6Li yields a thermal neutron mean free path of only 920 μm. This paper reports on the performance of LISe crystals in scintillation mode for its potential use as a converter screen for thermal/cold neutron imaging. The spatial resolution of LISe, determined using a 10% value of the Modulation Transfer Function (MTF), was found to not scale linearly with thickness. Crystals having a thickness of 450 μm or larger resulted in an average spatial resolutionmore » of 67 μm, and the thinner crystals exhibited an increase in spatial resolution down to the Nyquist frequency of the CCD. The highest measured spatial resolution of 198 μm thick LISe (27 μm) outperforms a commercial 50 μm thick ZnS(Cu):6LiF scintillation screen (100 μm) by more than a factor of three. For the thicknesses considered in this study, it has been found that the light yield of LISe did not scale with its thickness, suggesting the need for optimizing the synthesis to enhance the scintillation mechanism. Absorption measurements indicate that the 6Li concentration is uniform throughout the samples and its absorption efficiency as a function of thickness follows general nuclear theory, indicating that the variation in apparent brightness is likely due to a combination of particle escape, light transport, and activation of the scintillation mechanisms. As a result, the presence of 115In and its long-lived 116In activation product did not result in ghosting (memory of past neutron exposure), demonstrating potential for using LISe for imaging transient systems.« less

  10. Scintillation Characterization of Doped Cesium Hafnium Chloride (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Rowe, Emmanuel; Goodwin, Brandon; Bhattacharya, Pijush; Burger, Arnold; Stowe, Ashley; Cherepy, Nerine; Payne, Steve

    2016-09-01

    The scintillators currently providing the best energy resolution lower than 2.6% at 662 keV and sizes larger than 1 in. dia. 1 in. height are LaBr3(Ce) and SrI2(Eu). Despite energy resolution and decay time performance of LaBr3(Ce), the intrinsic radioactivity, due to naturally occurring 138La isotope in the matrix is a limitation for low count rate applications such as radioisotope identification of weak sources. Cesium Hafnium Chloride (CHC) is a high effective atomic number (Zeff=58) moderate density (3.86 g/cm3) scintillator for gamma spectroscopy, offering a cubic crystal structure, no intrinsic radioactivity, and highly proportional light yield, without intentional doping. CHC boasts a cubic crystal structure that is isostructural to K2HfCl6 and analogous to calcium fluoride with cesium ions in the fluorine ion position and the [HfCl6]2- octahedral replacing calcium ions. The scintillation of CHC is centered at 400 nm, with a principal decay time of 4.37 μs, a light yield of up to 54,000 photons/MeV and energy resolution of 3.3% at 662 keV and we report on the effects of doping on the scintillation properties of CHC.

  11. Properties of scintillator solutes

    SciTech Connect

    Fluornoy, J.M.

    1998-06-01

    This special report summarizes measurements of the spectroscopic and other properties of the solutes that were used in the preparation of several new liquid scintillators developed at EG and G/Energy Measurements/Santa Barbara Operations (the precursor to Bechtel Nevada/Special Technologies Laboratory) on the radiation-to-light converter program. The data on the individual compounds are presented in a form similar to that used by Prof. Isadore Berlman in his classic handbook of fluorescence spectra. The temporal properties and relative efficiencies of the new scintillators are presented in Table 1, and the efficiencies as a function of wavelength are presented graphically in Figure 1. In addition, there is a descriptive glossary of the abbreviations used herein. Figure 2 illustrates the basic structures of some of the compounds and of the four solvents reported in this summary. The emission spectra generally exhibit more structure than the absorption spectra, with the result that the peak emission wavelength for a given compound may lie several nm away from the wavelength, {lambda}{sub avg}, at the geometric center of the emission spectrum. Therefore, the author has chosen to list absorption peaks, {lambda}{sub max}, and emission {lambda}{sub avg} values in Figures 3--30, as being most illustrative of the differences between the compounds. The compounds, BHTP, BTPB, ADBT, and DPTPB were all developed on this program. P-terphenyl, PBD, and TPB are commercially available blue emitters. C-480 and the other longer-wavelength emitters are laser dyes available commercially from Exciton Corporation. 1 ref., 30 figs.

  12. Performance of Europium-Doped Strontium Iodide, Transparent Ceramics and Bismuth-loaded Polymer Scintillators

    SciTech Connect

    Cherepy, Nerine; Payne, Stephen A.; Sturm, Benjamin; O’Neal, S P; Seeley, Zachary; Drury, Owen; Haselhorst, L K; Rupert, B. L.; Sanner, Robert; Thelin, P; Fisher, S E; Hawrami, Rastgo; Shah, Kanai; Burger, Arnold; Ramey, Joanne Oxendine; Boatner, Lynn A

    2011-01-01

    Recently discovered scintillators for gamma ray spectroscopy, single crystal SrI2(Eu), GYGAG(Ce) transparent ceramic and Bismuth-loaded plastics offer resolution and fabrication advantages compared to commercial scintillators, such as NaI(Tl) and standard PVT plastic. Energy resolution at 662 keV of 2.7% is obtained with SrI2(Eu), while 4.5% is obtained with GYGAG(Ce). A new transparent ceramic scintillator for radiographic imaging systems, GLO(Eu) offers high light yield of ~75,000 Ph/MeV, high stopping, and low radiation damage. Implementation of single crystal SrI2(Eu), Gd-based transparent ceramics, and Bi-loaded plastic scintillators can advance the state-of-the art in ionizing radiation detection systems.

  13. Performance of europium-doped strontium iodide, transparent ceramics and bismuth-loaded polymer scintillators

    NASA Astrophysics Data System (ADS)

    Cherepy, N. J.; Payne, S. A.; Sturm, B. W.; O'Neal, S. P.; Seeley, Z. M.; Drury, O. B.; Haselhorst, L. K.; Rupert, B. L.; Sanner, R. D.; Thelin, P. A.; Fisher, S. E.; Hawrami, R.; Shah, K. S.; Burger, A.; Ramey, J. O.; Boatner, L. A.

    2011-09-01

    Recently discovered scintillators for gamma ray spectroscopy - single-crystal SrI2(Eu), GYGAG(Ce) transparent ceramic and Bismuth-loaded plastics - offer resolution and fabrication advantages compared to commercial scintillators, such as NaI(Tl) and standard PVT plastic. Energy resolution at 662 keV of 2.7% is obtained with SrI2(Eu), while 4.5% is obtained with GYGAG(Ce). A new transparent ceramic scintillator for radiographic imaging systems, GLO(Eu), offers high light yield of 70,000 Photons/MeV, high stopping, and low radiation damage. Implementation of single-crystal SrI2(Eu), Gd-based transparent ceramics, and Bi-loaded plastic scintillators can advance the state-of-the art in ionizing radiation detection systems.

  14. Application of scintillating properties of liquid xenon and silicon photomultiplier technology to medical imaging

    NASA Astrophysics Data System (ADS)

    Gomez-Cadenas, J. J.; Benlloch-Rodriguez, J. M.; Ferrario, Paola

    2016-04-01

    We describe a new positron emission time-of-flight apparatus using liquid xenon. The detector is based in a liquid xenon scintillating cell. The cell shape and dimensions can be optimized depending on the intended application. In its simplest form, the liquid xenon scintillating cell is a box in which two faces are covered by silicon photomultipliers and the others by a reflecting material such as Teflon. It is a compact, homogenous and highly efficient detector which shares many of the desirable properties of monolithic crystals, with the added advantage of high yield and fast scintillation offered by liquid xenon. Our initial studies suggest that good energy and spatial resolution comparable with that achieved by lutetium oxyorthosilicate crystals can be obtained with a detector based in liquid xenon scintillating cells. In addition, the system can potentially achieve an excellent coincidence resolving time of better than 100 ps.

  15. Performance of Europium-Doped Strontium Iodide, Transparent Ceramics and Bismuth-loaded Polymer Scintillators

    SciTech Connect

    Cherepy, N J; Payne, S A; Sturm, B W; O'Neal, S P; Seeley, Z M; Drury, O B; Haselhorst, L K; Rupert, B L; Sanner, R D; Thelin, P A; Fisher, S E; Hawrami, R; Shah, K S; Burger, A; Ramey, J O; Boatner, L A

    2011-08-30

    Recently discovered scintillators for gamma ray spectroscopy, single crystal SrI{sub 2}(Eu), GYGAG(Ce) transparent ceramic and Bismuth-loaded plastics, offer resolution and fabrication advantages compared to commercial scintillators, such as NaI(Tl) and standard PVT plastic. Energy resolution at 662 keV of 2.7% is obtained with SrI{sub 2}(Eu), while 4.5% is obtained with GYGAG(Ce). A new transparent ceramic scintillator for radiographic imaging systems, GLO(Eu) offers high light yield of 70,000 Photons/MeV, high stopping, and low radiation damage. Implementation of single crystal SrI{sub 2}(Eu), Gd-based transparent ceramics, and Bi-loaded plastic scintillators can advance the state-of-the art in ionizing radiation detection systems.

  16. Improved Growth Methods for LaBr3 Scintillation Radiation Detectors

    SciTech Connect

    McGregor, Douglas S

    2011-05-01

    The objective is to develop advanced materials for deployment as high-resolution gamma ray detectors. Both LaBr3 and CeBr3 are advanced scintillation materials, and will be studied in this research. Prototype devices, in collaboration Sandia National Laboratories, will be demonstrated along with recommendations for mass production and deployment. It is anticipated that improved methods of crystal growth will yield larger single crystals of LaBr3 for deployable room-temperature operated gamma radiation spectrometers. The growth methods will be characterized. The LaBr3 and CeBr3 scintillation crystals will be characterized for light yield, spectral resolution, and for hardness.

  17. Combinatorial Screening of Advanced Scintillators for High Resolution X-ray Detectors

    SciTech Connect

    Cheng, Shifan; Tao, Dejie; Lynch, Michael; Yuan, Xianglong; Li, Yiqun

    2008-05-12

    The lack of efficient scintillators is a major problem for developing powerful x-ray detectors that are widely used in homeland security, industrial and scientific research. Intematix has developed and applied a high throughput screening process and corresponding crystal growth technology to significantly speed up the discovery process for new efficient scintillators. As a result, Intematix has invented and fabricated three new scintillators both in powder and bulk forms, which possess promising properties such as better radiation hardness and better matching for silicon diode.

  18. Scintillator fiber optic long counter

    DOEpatents

    McCollum, Tom; Spector, Garry B.

    1994-01-01

    A flat response position sensitive neutron detector capable of providing neutron spectroscopic data utilizing scintillator fiber optic filaments embedded in a neutron moderating housing having an open end through which neutrons enter to be detected.

  19. Scintillator fiber optic long counter

    DOEpatents

    McCollum, T.; Spector, G.B.

    1994-03-29

    A flat response position sensitive neutron detector capable of providing neutron spectroscopic data utilizing scintillator fiber optic filaments embedded in a neutron moderating housing having an open end through which neutrons enter to be detected is described. 11 figures.

  20. Neutron crosstalk between liquid scintillators

    DOE PAGES

    Verbeke, J. M.; Prasad, M. K.; Snyderman, N. J.

    2015-05-01

    We propose a method to quantify the fractions of neutrons scattering between liquid scintillators. Using a spontaneous fission source, this method can be utilized to quickly characterize an array of liquid scintillators in terms of crosstalk. The point model theory due to Feynman is corrected to account for these multiple scatterings. Using spectral information measured by the liquid scintillators, fractions of multiple scattering can be estimated, and mass reconstruction of fissile materials under investigation can be improved. Monte Carlo simulations of mono-energetic neutron sources were performed to estimate neutron crosstalk. A californium source in an array of liquid scintillators wasmore » modeled to illustrate the improvement of the mass reconstruction.« less

  1. Properties of Ce-activated alkali-lutetium double phosphate scintillators

    SciTech Connect

    Wiśniewski, D.; Wojtowicz, A. J.; Boatner, Lynn A

    2010-01-01

    The scintillation properties of Ce-activated alkali-lutetium double phosphate single crystals that vary with the alkali ion type and activation level are summarized and compared. The materials investigated here have been identified as fast and efficient scintillators for the detection of x-ray and radiation, and in case of Li3Lu(PO4)2:Ce, for thermal neutron detection as well.

  2. About NICADD extruded scintillating strips

    SciTech Connect

    Dyshkant, A.; Beznosko, D.; Blazey, G.; Chakraborty, D.; Francis, K.; Kubik, D.; Lima, J.G.; Rykalin, V.; Zutshi, v.; Baldina, E.; Bross, A.; Deering, P.; Nebel, T.; Pla-Dalmau, A.; Schellpfeffer, J.; Serritella, C.; Zimmerman, J.; /Fermilab

    2005-04-01

    The results of control measurements of extruded scintillating strip responses to a radioactive source Sr-90 are provided, and details of strip choice, preparation, and method of measurement are included. About four hundred one meter long extruded scintillating strips were measured at four different points. These results were essential for prototyping a tail catcher and muon tracker for a future international electron positron linear collider detector.

  3. Positive hysteresis of Ce-doped GAGG scintillator

    NASA Astrophysics Data System (ADS)

    Yanagida, Takayuki; Fujimoto, Yutaka; Koshimizu, Masanori; Watanabe, Kenichi; Sato, Hiroki; Yagi, Hideki; Yanagitani, Takagimi

    2014-10-01

    Positive hysteresis and radiation tolerance to high-dose radiation exposure were investigated for Ce 1% and 3% doped Gd3(Al, Ga)5O12 (Ce:GAGG) crystal scintillator on comparison with other garnet scintillators such Ce:YAG, Ce:LuAG, Pr:LuAG, and ceramic Ce:GAGG. When they were irradiated by several Gy 60Co γ-rays, Ce 1% doped GAGG crystal exhibited ∼20% light yield enhancement (positive hysteresis). This is the first time to observe positive hysteresis in Ce doped GAGG. On the other hand, other garnet materials did not show the positive hysteresis and their light yields were stable after 800 Gy irradiation except Pr:LuAG. The light yield of Pr:LuAG decreased largely. When irradiated Ce:GAGG which showed positive hysteresis was evaluated in Synchrotron facility (UVSOR), new excitation band was created around 60 nm.

  4. Methods of Fabricating Scintillators with Radioisotopes for Beta Battery Applications

    NASA Technical Reports Server (NTRS)

    Rensing, Noa M.; Squillante, Michael R.; Tieman, Timothy C.; Higgins, William; Shiriwadkar, Urmila

    2013-01-01

    Technology has been developed for a class of self-contained, long-duration power sources called beta batteries, which harvest the energy contained in the radioactive emissions from beta decay isotopes. The new battery is a significant improvement over the conventional phosphor/solar cell concept for converting this energy in three ways. First, the thin phosphor is replaced with a thick scintillator that is transparent to its own emissions. By using a scintillator sufficiently thick to completely stop all the beta particles, efficiency is greatly improved. Second, since the energy of the beta particles is absorbed in the scintillator, the semiconductor photodetector is shielded from radiation damage that presently limits the performance and lifetime of traditional phosphor converters. Finally, instead of a thin film of beta-emitting material, the isotopes are incorporated into the entire volume of the thick scintillator crystal allowing more activity to be included in the converter without self-absorption. There is no chemical difference between radioactive and stable strontium beta emitters such as Sr-90, so the beta emitter can be uniformly distributed throughout a strontium based scintillator crystal. When beta emitter material is applied as a foil or thin film to the surface of a solar cell or even to the surface of a scintillator, much of the radiation escapes due to the geometry, and some is absorbed within the layer itself, leading to inefficient harvesting of the energy. In contrast, if the emitting atoms are incorporated within the scintillator, the geometry allows for the capture and efficient conversion of the energy of particles emitted in any direction. Any gamma rays associated with secondary decays or Bremsstrahlung photons may also be absorbed within the scintillator, and converted to lower energy photons, which will in turn be captured by the photocell or photodiode. Some energy will be lost in this two-stage conversion process (high-energy particle

  5. Extruded plastic scintillator including inorganic powders

    DOEpatents

    Bross, Alan D.; Mellott, Kerry L.; Pla-Dalmau, Anna

    2006-06-27

    A method for producing a plastic scintillator is disclosed. A plurality of nano-sized particles and one or more dopants can be combined with a plastic material for the formation of a plastic scintillator thereof. The nano-sized particles, the dopant and the plastic material can be combined within the dry inert atmosphere of an extruder to produce a reaction that results in the formation of a plastic scintillator thereof and the deposition of energy within the plastic scintillator, such that the plastic scintillator produces light signifying the detection of a radiative element. The nano-sized particles can be treated with an inert gas prior to processing the nano-sized particles, the dopant and the plastic material utilizing the extruder. The plastic scintillator can be a neutron-sensitive scintillator, x-ray sensitive scintillator and/or a scintillator for the detection of minimum ionizing particles.

  6. Performance of photomultiplier tubes and sodium iodide scintillation detector systems

    NASA Technical Reports Server (NTRS)

    Meegan, C. A.

    1981-01-01

    The performance of photomultiplier tubes (PMT's) and scintillation detector systems incorporating 50.8 by 1.27 cm NaI (T l) crystals was investigated to determine the characteristics of the photomultiplier tubes and optimize the detector geometry for the Burst and Transient Source Experiment on the Gamma Ray Observatory. Background information on performance characteristics of PMT's and NaI (T l) detectors is provided, procedures for measurement of relevant parameters are specified, and results of these measurements are presented.

  7. Scintillating bolometers for the LUCIFER project

    NASA Astrophysics Data System (ADS)

    Pattavina, L.; LUCIFER Collaboration

    2016-05-01

    Neutrinoless double beta decay (0vββ) is one of the most sensitive probes for physics beyond the Standard Model, providing unique information on the nature and masses of neutrinos. In order to explore the so-called inverted neutrino mass hierarchy region a further improvement on the upcoming 0vββ experiment is needed. In this respect, scintillating bolometers are the suitable technology for achieving such goal: they ensure excellent energy resolution and highly efficient particle discrimination. The LUCIFER project aims at deploying the first array of enriched scintillating bolometers for the investigation of 0vββ of 82Se. The matrix which embeds the source is an array of Zn 82Se crystals, where enriched 82Se is used as decay isotope. Taking advantage of the large Q-value (2997 keV) and of the particle discrimination, the expected background rate in the region of interest is as low as 10-3 c/keV/kg/y. The foreseen sensitivity after 2 years of live time will be 1.8×1025 years. We will report on the potential of such technology and on the present status of the project.

  8. Characterization of cerium fluoride nanocomposite scintillators

    SciTech Connect

    Stange, Sy; Esch, Ernst I; Brown, Leif O; Couture, Aaron J; Mckigney, Edward A; Muenchausen, Ross E; Del Sesto, Rico E; Gilbertson, Robert D; Mccleskey, T Mark; Reifarth, Rene

    2009-01-01

    Measurement of the neutron capture cross-sections of a number of short-lived isotopes would advance both pure and applied scientific research. These cross-sections are needed for calculation of criticality and waste production estimates for the Advanced Fuel Cycle Initiative, for analysis of data from nuclear weapons tests, and to improve understanding of nucleosynthesis. However, measurement of these cross-sections would require a detector with a faster signal decay time than those used in existing neutron capture experiments. Crystals of faster detector materials are not available in sufficient sizes and quantities to supply these large-scale experiments. Instead, we propose to use nanocomposite detectors, consisting of nanoscale particles of a scintillating material dispersed in a matrix material. We have successfully fabricated cerium fluoride (CeF{sub 3}) nanoparticles and dispersed them in a liquid matrix. We have characterized this scintillator and have measured its response to neutron capture. Results of the optical, structural, and radiation characterization will be presented.

  9. New scintillator materials for future and present facilities

    SciTech Connect

    Camera, Franco; Giaz, Agnese

    2015-02-24

    In the recent years LaBr3:Ce crystals started a new generation of high performing scintillator detectors. In fact, a large number of different, new and promising scintillators are now becoming commercially available, as for example CeBr{sub 3}, CLYC, SrI{sub 2}. Some others, like GYGAG:Ce, CLLB, CLLC, will be available in the near future. The CLYC crystal enriched with {sup 6}Li provides extremely high efficiency for thermal neutron identification and detection with performances comparable to {sup 3}He tubes. The CLYC enriched with {sup 7}Li can provide the direct measurement of the neutron kinetic energy from the energy pulse signal. The most recent R and D activity shows that ‘co-doping’ technique has the effect to improve the crystal proportionality and the mechanical properties thus significantly increasing the reliability and energy resolution of LaBr{sub 3};Ce and CeBr{sub 3} scintillators. Such a new generation of detectors can be the backbone for the detectors array of the future accelerator facilities as for example ELI-NP which will provide very intense high-energy γ-ray beam with very low bandwidth.

  10. Fundamental Limits of Scintillation Detector Timing Precision

    PubMed Central

    Derenzo, Stephen E.; Choong, Woon-Seng; Moses, William W.

    2014-01-01

    In this paper we review the primary factors that affect the timing precision of a scintillation detector. Monte Carlo calculations were performed to explore the dependence of the timing precision on the number of photoelectrons, the scintillator decay and rise times, the depth of interaction uncertainty, the time dispersion of the optical photons (modeled as an exponential decay), the photodetector rise time and transit time jitter, the leading-edge trigger level, and electronic noise. The Monte Carlo code was used to estimate the practical limits on the timing precision for an energy deposition of 511 keV in 3 mm × 3 mm × 30 mm Lu2SiO5:Ce and LaBr3:Ce crystals. The calculated timing precisions are consistent with the best experimental literature values. We then calculated the timing precision for 820 cases that sampled scintillator rise times from 0 to 1.0 ns, photon dispersion times from 0 to 0.2 ns, photodetector time jitters from 0 to 0.5 ns fwhm, and A from 10 to 10,000 photoelectrons per ns decay time. Since the timing precision R was found to depend on A−1/2 more than any other factor, we tabulated the parameter B, where R = BA−1/2. An empirical analytical formula was found that fit the tabulated values of B with an rms deviation of 2.2% of the value of B. The theoretical lower bound of the timing precision was calculated for the example of 0.5 ns rise time, 0.1 ns photon dispersion, and 0.2 ns fwhm photodetector time jitter. The lower bound was at most 15% lower than leading-edge timing discrimination for A from 10 to 10,000 photoelectrons/ns. A timing precision of 8 ps fwhm should be possible for an energy deposition of 511 keV using currently available photodetectors if a theoretically possible scintillator were developed that could produce 10,000 photoelectrons/ns. PMID:24874216

  11. Fundamental limits of scintillation detector timing precision.

    PubMed

    Derenzo, Stephen E; Choong, Woon-Seng; Moses, William W

    2014-07-07

    In this paper we review the primary factors that affect the timing precision of a scintillation detector. Monte Carlo calculations were performed to explore the dependence of the timing precision on the number of photoelectrons, the scintillator decay and rise times, the depth of interaction uncertainty, the time dispersion of the optical photons (modeled as an exponential decay), the photodetector rise time and transit time jitter, the leading-edge trigger level, and electronic noise. The Monte Carlo code was used to estimate the practical limits on the timing precision for an energy deposition of 511 keV in 3 mm × 3 mm × 30 mm Lu2SiO5:Ce and LaBr3:Ce crystals. The calculated timing precisions are consistent with the best experimental literature values. We then calculated the timing precision for 820 cases that sampled scintillator rise times from 0 to 1.0 ns, photon dispersion times from 0 to 0.2 ns, photodetector time jitters from 0 to 0.5 ns fwhm, and A from 10 to 10,000 photoelectrons per ns decay time. Since the timing precision R was found to depend on A(-1/2) more than any other factor, we tabulated the parameter B, where R = BA(-1/2). An empirical analytical formula was found that fit the tabulated values of B with an rms deviation of 2.2% of the value of B. The theoretical lower bound of the timing precision was calculated for the example of 0.5 ns rise time, 0.1 ns photon dispersion, and 0.2 ns fwhm photodetector time jitter. The lower bound was at most 15% lower than leading-edge timing discrimination for A from 10 to 10,000 photoelectrons ns(-1). A timing precision of 8 ps fwhm should be possible for an energy deposition of 511 keV using currently available photodetectors if a theoretically possible scintillator were developed that could produce 10,000 photoelectrons ns(-1).

  12. First-principles Electronic Structure Calculations for Scintillation Phosphor Nuclear Detector Materials

    NASA Astrophysics Data System (ADS)

    Canning, Andrew

    2013-03-01

    Inorganic scintillation phosphors (scintillators) are extensively employed as radiation detector materials in many fields of applied and fundamental research such as medical imaging, high energy physics, astrophysics, oil exploration and nuclear materials detection for homeland security and other applications. The ideal scintillator for gamma ray detection must have exceptional performance in terms of stopping power, luminosity, proportionality, speed, and cost. Recently, trivalent lanthanide dopants such as Ce and Eu have received greater attention for fast and bright scintillators as the optical 5d to 4f transition is relatively fast. However, crystal growth and production costs remain challenging for these new materials so there is still a need for new higher performing scintillators that meet the needs of the different application areas. First principles calculations can provide a useful insight into the chemical and electronic properties of such materials and hence can aid in the search for better new scintillators. In the past there has been little first-principles work done on scintillator materials in part because it means modeling f electrons in lanthanides as well as complex excited state and scattering processes. In this talk I will give an overview of the scintillation process and show how first-principles calculations can be applied to such systems to gain a better understanding of the physics involved. I will also present work on a high-throughput first principles approach to select new scintillator materials for fabrication as well as present more detailed calculations to study trapping process etc. that can limit their brightness. This work in collaboration with experimental groups has lead to the discovery of some new bright scintillators. Work supported by the U.S. Department of Homeland Security and carried out under U.S. Department of Energy Contract no. DE-AC02-05CH11231 at Lawrence Berkeley National Laboratory.

  13. Molecular origins of scintillation in organic scintillators (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Feng, Patrick; Mengesha, Wondwosen; Myllenbeck, Nicholas

    2016-09-01

    Organic-based scintillators are indispensable materials for radiation detection owing to their high sensitivity to fast neutrons, low cost, and tailorable properties. There has been a recent resurgence of interest in organic scintillators due to exciting discoveries related to neutron discrimination and gamma-ray spectroscopy, which represent capabilities previously thought not possible in these materials. I will discuss our development of crystalline and polymer-based scintillators for these applications. Structure-property relationships related to intermolecular interactions and host-guest electronic exchange will be discussed in the context of energy-transfer pathways relevant to scintillation. An emphasis will be placed on the rational design of these materials, as guided by first principles and DFT calculations. Two related topics will be discussed: 1) Incorporation of organometallic triplet-harvesting additives to plastic scintillator matrices to confer a 'two-state' (singlet and triplet) luminescence signature to different types of ionizing radiation. This approach relies upon energetic and spatial overlap between the donor and acceptor excited states for efficient electronic exchange. Key considerations also include synthetic modification of the luminescence spectra and kinetics, as well as the addition of secondary additives to increase the recombination efficiency. 2) Design of organotin-containing plastic scintillators as a route towards gamma-ray spectroscopy. Organometallic compounds were selected on the basis of distance-dependent quenching relationships, phase compatibility with the polymer matrix, and the gamma-ray cross sections. This approach is guided by molecular modeling and radiation transport modeling to achieve the highest possible detection sensitivity luminescence intensity.

  14. FNAL-NICADD extruded scintillator

    SciTech Connect

    Beznosko, D.; Bross, A.; Dyshkant, A.; Pla-Dalmau, A.; Rykalin, V.; /Northern Illinois U.

    2005-09-01

    The possibility to produce a scintillator that satisfies the demands of physicists from different science areas has emerged with the installation of an extrusion line at Fermi National Accelerator Laboratory (FNAL). The extruder is the product of the fruitful collaboration between FNAL and Northern Illinois Center for Accelerator and Detector Development (NICADD) at Northern Illinois University (NIU). The results from the light output, light attenuation length and mechanical tolerance indicate that FNAL-NICADD scintillator is of high quality. Improvements in the extrusion die will yield better scintillator profiles and decrease the time needed for initial tuning. This paper will present the characteristics of the FNAL-NICADD scintillator based on the measurements performed. They include the response to MIPs from cosmic rays for individual extruded strips and irradiation studies where extruded samples were irradiated up to 1 Mrad. We will also discuss the results achieved with a new die design. The attractive perspective of using the extruded scintillator with MRS (Metal Resistive Semiconductor) photodetector readout will also be shown.

  15. Scintillation detectors in gamma spectral logging; geometry, absorption and calibration

    USGS Publications Warehouse

    Schimschal, Ulrich

    1980-01-01

    The theory for the evaluation of the effects of geometry in gamma ray absorption is developed for cylindrical scintillation detectors as applicable to borehole gamma spectrometry. The results of a laboratory experiment are shown for comparison. A calibration procedure to determine detector efficiency is given for application to borehole probes. It is shown that the response of a crystal can be separated in terms of geometric effects and instrumentation effects. It is also shown that approximating crystal detectors with point detectors in mathematical theory is grossly oversimplified. (USGS)

  16. Characterizing and simulation the scintillation properties of zinc oxide nanowires in AAO membrane for medical imaging applications

    NASA Astrophysics Data System (ADS)

    Esfandi, F.; Saramad, S.; Rezaei Shahmirzadi, M.

    2017-07-01

    In this work, a new method is proposed for extracting some X-ray detection properties of ZnO nanowires electrodeposited on Anodized Aluminum Oxide (AAO) nanoporous template. The results show that the detection efficiency for 12μm thickness of zinc oxide nano scintillator at an energy of 9.8 keV, near the K-edge of ZnO (9.65 keV), is 24%. The X-rays that interact with AAO can also generate electrons that reach the nano scintillator. The scintillation events of these electrons are seen as a low energy tail in the spectrum. In addition, it is found that all the X-rays that are absorbed in 300 nm thickness of the gold layer on the top of the zinc oxide nanowires can participate in the scintillation process with an efficiency of 6%. Hence, the scintillation detection efficiency of the whole detector for 9.8 keV X-ray energy is 30%. The simulation results from Geant4 and the experimental detected photons per MeV energy deposition are also used to extract the light yield of the zinc oxide nano scintillator. The results show that the light yield of the zinc oxide nanowires deposited by the electrochemical method is approximately the same as for single crystal zinc oxide scintillator (9000). Much better spatial resolution of this nano scintillator in comparison to the bulk ones is an advantage which candidates this nano scintillator for medical imaging applications.

  17. Radiopure metal-loaded liquid scintillator

    SciTech Connect

    Rosero, Richard; Yeh, Minfang

    2015-08-17

    Metal-loaded liquid scintillator plays a key role in particle and nuclear physics experiments. The applications of metal ions in various neutrino experiments and the purification methods for different scintillator components are discussed in this paper.

  18. Radiopure Metal-Loaded Liquid Scintillator

    SciTech Connect

    Rosero, Richard; Yeh, Minfang

    2015-03-18

    Metal-loaded liquid scintillator plays a key role in particle and nuclear physics experiments. The applications of metal ions in various neutrino experiments and the purification methods for different scintillator components are discussed in this paper.

  19. Advances in scintillators for medical imaging applications

    NASA Astrophysics Data System (ADS)

    van Loef, Edgar V.; Shah, Kanai S.

    2014-09-01

    A review is presented of some recent work in the field of inorganic scintillator research for medical imaging applications, in particular scintillation detectors for Single-Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET).

  20. Characteristics of Un doped and Europium-dopedSrI2 Scintillator Detectors

    SciTech Connect

    Sturm, Benjamin; Cherepy, Nerine; Drury, Owen; Thelin, P; Fisher, S E; O’Neal, S P; Payne, Stephen A.; Burger, Arnold; Boatner, Lynn A; Ramey, Joanne Oxendine; Shah, Kanai; Hawrami, Rastgo

    2012-01-01

    High energy resolution gamma-ray detectors that can be formed into relatively large sizes while operating at room temperature offer many advantages for national security applications. We are working toward that goal through the development of SrI{sub 2}(Eu) scintillator detectors, which routinely provide <;3.0% energy resolution at 662 keV with volumes >;10 cm{sup 3}. In this study, we have tested pure, undoped SrI{sub 2} to gain a better understanding of the scintillation properties and spectroscopic performance achievable without activation. An undoped crystal grown from 99.999% pure SrI{sub 2} pellets was tested for its spectroscopic performance, its light yield, and uniformity of scintillation light collection as a function of gamma-ray interaction position relative to the crystal growth direction. Undoped SrI{sub 2} was found to provide energy resolution of 5.3% at 662 keV, and the light collection nonuniformity varied by only 0.72% over the length of the crystal. Measurements of both a 3% Eu-doped and the undoped SrI{sub 2} crystal were carried out in the SLYNCI facility and indicate differences in their light yield non-proportionality. The surprisingly good scintillation properties of the pure SrI{sub 2} crystal suggests that with high-purity feedstock, further reduction of the Eu concentration can be made to grow larger crystals while not adversely impacting the spectroscopic performance.

  1. Liquid scintillator tiles for calorimetry

    DOE PAGES

    Amouzegar, M.; Belloni, A.; Bilki, B.; ...

    2016-11-28

    Future experiments in high energy and nuclear physics may require large, inexpensive calorimeters that can continue to operate after receiving doses of 50 Mrad or more. Also, the light output of liquid scintillators suffers little degradation under irradiation. However, many challenges exist before liquids can be used in sampling calorimetry, especially regarding developing a packaging that has sufficient efficiency and uniformity of light collection, as well as suitable mechanical properties. We present the results of a study of a scintillator tile based on the EJ-309 liquid scintillator using cosmic rays and test beam on the light collection efficiency and uniformity,more » and some preliminary results on radiation hardness.« less

  2. Scintillating glass fiber neutron senors

    SciTech Connect

    Abel, K.H.; Arthur, R.J.; Bliss, M.

    1994-04-01

    Cerium-doped lithium-silicate glass fibers have been developed at Pacific Northwest Laboratory (PNL) for use as thermal neutron detectors. By using highly-enriched {sup 6} Li , these fibers efficiently capture thermal neutrons and produce scintillation light that can be detected at the ends of the fibers. Advantages of scintillating fibers over {sup 3}He or BF{sub 3} proportional tubes include flexibility in geometric configuration, ruggedness in high-vibration environments, and less detector weight for the same neutron sensitivity. This paper describes the performance of these scintillating fibers with regard to count rates, pulse height spectra, absolute efficiencies, and neutron/gamma discrimination. Fibers with light transmission lengths (1/e) of greater than 2 m have been produced at PNL. Neutron sensors in fiber form allow development of a variety of neutron detectors packaged in previously unavailable configurations. Brief descriptions of some of the devices already produced are included to illustrate these possibilities.

  3. Unitary scintillation detector and system

    DOEpatents

    McElhaney, Stephanie A.; Chiles, Marion M.

    1994-01-01

    The invention is a unitary alpha, beta, and gamma scintillation detector and system for sensing the presence of alpha, beta, and gamma radiations selectively or simultaneously. The scintillators are mounted in a light-tight housing provided with an entrance window for admitting alpha, beta, and gamma radiation and excluding ambient light from the housing. Light pulses from each scintillator have different decay constants that are converted by a photosensitive device into corresponding differently shaped electrical pulses. A pulse discrimination system identifies the electrical pulses by their respective pulse shapes which are determined by decay time. The identified electrical pulses are counted in separate channel analyzers to indicate the respective levels of sensed alpha, beta, and gamma radiations.

  4. Unitary scintillation detector and system

    DOEpatents

    McElhaney, S.A.; Chiles, M.M.

    1994-05-31

    The invention is a unitary alpha, beta, and gamma scintillation detector and system for sensing the presence of alpha, beta, and gamma radiations selectively or simultaneously. The scintillators are mounted in a light-tight housing provided with an entrance window for admitting alpha, beta, and gamma radiation and excluding ambient light from the housing. Light pulses from each scintillator have different decay constants that are converted by a photosensitive device into corresponding differently shaped electrical pulses. A pulse discrimination system identifies the electrical pulses by their respective pulse shapes which are determined by decay time. The identified electrical pulses are counted in separate channel analyzers to indicate the respective levels of sensed alpha, beta, and gamma radiations. 10 figs.

  5. Development of radiation hard scintillators

    NASA Astrophysics Data System (ADS)

    Markley, F.; Woods, D.; Pla-Dalmau, A.; Foster, G.; Blackburn, R.

    1993-01-01

    Substantial improvements have been made in the radiation hardness of plastic scintillators. Cylinders of scintillating materials 2.2 cm in diameter and 1 cm thick have been exposed to 10 Mrads of gamma rays at a dose rate of 1 Mrad/h in a nitrogen atmosphere. One of the formulations tested showed an immediate decrease in pulse height of only 4% and has remained stable for 12 days while annealing in air. By comparison a commercial PVT scintillator showed an immediate decrease of 58% and after 43 days of annealing in air it improved to a 14% loss. The formulated sample consisted of 70 parts by weight of Dow polystyrene, 30 pbw of pentaphenyltrimethyltrisiloxane (Dow Corning DC 705 oil), 2 pbw of p-terphenyl, 0.2 pbw of tetraphenylbutadiene, and 0.5 pbw of UVASIL299LM from Ferro.

  6. Scintillation-Hardened GPS Receiver

    NASA Technical Reports Server (NTRS)

    Stephens, Donald R.

    2015-01-01

    CommLargo, Inc., has developed a scintillation-hardened Global Positioning System (GPS) receiver that improves reliability for low-orbit missions and complies with NASA's Space Telecommunications Radio System (STRS) architecture standards. A software-defined radio (SDR) implementation allows a single hardware element to function as either a conventional radio or as a GPS receiver, providing backup and redundancy for platforms such as the International Space Station (ISS) and high-value remote sensing platforms. The innovation's flexible SDR implementation reduces cost, weight, and power requirements. Scintillation hardening improves mission reliability and variability. In Phase I, CommLargo refactored an open-source GPS software package with Kalman filter-based tracking loops to improve performance during scintillation and also demonstrated improved navigation during a geomagnetic storm. In Phase II, the company generated a new field-programmable gate array (FPGA)-based GPS waveform to demonstrate on NASA's Space Communication and Navigation (SCaN) test bed.

  7. Interstellar scintillations of pulsar radiation.

    PubMed

    Lang, K R

    1969-12-12

    Time fluctuations in the intensity of pulsed radiation from CP 0834, CP 1133, AP 1237, and CP 1919 have been investigated. Power spectra, modulation indices, frequency distributions, and decorrelation frequencies are consistent with scintillation theory. If it is assumed that these scintillations are due to irregularities in the interstellar medium that travel at a velocity of 20 kilometers per second, the irregularities have a scale size on the order of 10(4) kilometers and a distance from the earth of approximately 70 parsecs. These interstellar scintillations would not have been observed if the apparent angular diameters of the pulsars were larger than 0.3 X 10(-5) second of arc, and they would cause even a point radio source to have an apparent angular diameter of approximately 10(-3) second of arc at 318 megahertz.

  8. Development of radiation hard scintillators

    SciTech Connect

    Markley, F.; Woods, D.; Pla-Dalmau, A.; Foster, G. ); Blackburn, R. )

    1992-05-01

    Substantial improvements have been made in the radiation hardness of plastic scintillators. Cylinders of scintillating materials 2.2 cm in diameter and 1 cm thick have been exposed to 10 Mrads of gamma rays at a dose rate of 1 Mrad/h in a nitrogen atmosphere. One of the formulations tested showed an immediate decrease in pulse height of only 4% and has remained stable for 12 days while annealing in air. By comparison a commercial PVT scintillator showed an immediate decrease of 58% and after 43 days of annealing in air it improved to a 14% loss. The formulated sample consisted of 70 parts by weight of Dow polystyrene, 30 pbw of pentaphenyltrimethyltrisiloxane (Dow Corning DC 705 oil), 2 pbw of p-terphenyl, 0.2 pbw of tetraphenylbutadiene, and 0.5 pbw of UVASIL299LM from Ferro.

  9. Intrinsic scintillators: TlMgCl3 and TlCaI3

    NASA Astrophysics Data System (ADS)

    Hawrami, R.; Ariesanti, E.; Wei, H.; Finkelstein, J.; Glodo, J.; Shah, K. S.

    2017-10-01

    Two intrinsic scintillators TlMgCl3 and TlCaI3 with excellent energy resolution and fast scintillation decay are presented. Crack-free transparent crystals were successfully grown by the Bridgman method. The scintillation light yields of TlMgCl3 and TlCaI3 are approximately 30,600 ph/MeV and 42,200 ph/MeV, respectively. Their energy resolutions at 662 keV are 3.7% for TlMgCl3 and 6.2% for TlCaI3. The scintillation decay times of TlMgCl3 are 46 ns, 166 ns, and 449 ns. The scintillation decay times of TlCaI3 are 62 ns, 200 ns, and 1.44 μs. Under X-ray irradiation, the emission of TlMgCl3 is between 300 nm and 540 nm with the peak at 409 nm. TlCaI3 has a broad emission band between 300 nm and 750 nm. Due to their excellent scintillation properties, these two scintillators can be developed for gamma-ray detection. Additionally, TlMgCl3 is non-hygroscopic.

  10. Nanophosphor composite scintillator with a liquid matrix

    DOEpatents

    McKigney, Edward Allen; Burrell, Anthony Keiran; Bennett, Bryan L.; Cooke, David Wayne; Ott, Kevin Curtis; Bacrania, Minesh Kantilal; Del Sesto, Rico Emilio; Gilbertson, Robert David; Muenchausen, Ross Edward; McCleskey, Thomas Mark

    2010-03-16

    An improved nanophosphor scintillator liquid comprises nanophosphor particles in a liquid matrix. The nanophosphor particles are optionally surface modified with an organic ligand. The surface modified nanophosphor particle is essentially surface charge neutral, thereby preventing agglomeration of the nanophosphor particles during dispersion in a liquid scintillator matrix. The improved nanophosphor scintillator liquid may be used in any conventional liquid scintillator application, including in a radiation detector.

  11. New detecting techniques for a future calorimetry

    NASA Astrophysics Data System (ADS)

    Auffray, E.; Buganov, O.; Fedorov, A.; Korjik, M.; Lecoq, P.; Tamulaitis, G.; Tikhomirov, S.; Vasil'ev, A.

    2015-02-01

    In the last forty years, application of crystalline materials in homogeneous Electromagnetic Calorimeters has played a crucial role in the discovery of matter properties and promoted a continuous progress in the detecting technique. The detection systems progressed from small detectors based on NaI(Tl), CsI(Na), BaF2, PbF2, and Bi4Ge3O12 to giant Electromagnetic Calorimeters of CMS, ALICE Collaborations at LHC and PANDA Collaboration at FAIR, where the systems consisted of thousands lead tungstate PbWO4 scintillation crystals. Lead tungstate (PWO) became the most extensively used scintillation material in high energy physics experiments. PWO possesses a unique combination of scintillation properties including high energy and time resolutions in the detection of high energy particles. Here, we report on the results of the two photon absorption in PWO crystals obtained by pump-probe technique using ultra short laser pulses. The results demonstrate that the relaxation processes in PWO offer capability of this material to be used in detection systems to make a time stamp with precision close to 10-12 s or even better.

  12. An active electron polarized scintillating GSO target for neutrino physics

    NASA Astrophysics Data System (ADS)

    Baiboussinov, B.; Braggio, C.; Cardini, A.; Carugno, G.; Congiu, F.; Gain, S.; Galeazzi, G.; Lai, A.; Lehman, A.; Mocci, P.; Mura, A.; Quochi, F.; Saba, M.; Saitta, B.; Sartori, G.

    2012-12-01

    The feasibility of an electron-polarized, active target to be used as detector in neutrino scattering experiments, suggested by several theoretical papers, has been investigated. We report on the properties of the paramagnetic crystal Gd2SiO5 (GSO), in which 7.7% of the total number of electrons present can be polarized by lowering the temperature and applying an intense external magnetic field. The material magnetic susceptibility has been measured down to cryogenic temperatures showing that for H=5 T and T=4 K about 80% of the maximum allowed magnetization can be attained. Also the spectral and time response of the crystal have been characterized and the scintillation process has been studied using a photomultiplier to measure the response to gamma rays irradiation and cosmic rays operating the GSO crystal at 13.5 K. An avalanche photodiode (APD) readout of the scintillation signal from the GSO crystal has also been performed, since the magnetic field-independent response of this device allows it to be placed close to the crystal in the cryogenic environment.

  13. Scintillator Cosmic Ray Super Telescope

    NASA Astrophysics Data System (ADS)

    González, L. X.; Valdés-Galicia, J. F.; Matsubara, Y.; Nagai, Y.; Itow, Y.; Sako, T.; López, D.; Mitsuka, G.; Munakata, K.; Kato, C.; Yasue, S.; Kosai, M.; Tsurusashi, M.; Nakamo, Y.; Shibata, S.; Takamaru, H.; Kojima, H.; Tsuchiya, H.; Watanabe, K.; Koi, T.; Fragoso, E.; Hurtado, A.; Musalem, O.

    2013-04-01

    The Scintillator Cosmic Ray Super Telescope (SciCRST) is a new experiment to detect solar neutrons, and also it is expected to work as a muon and cosmic ray detector. The SciCRST consist of 14,848 plastic scintillator bars, and it will be installed at the top of Sierra Negra volcano, Mexico, 4580 m.a.s.l. We use a prototype, called as miniSciBar, to test the hardware and software of the final experiment. In this paper, we present the status and details of the experiment, and results of the prototype.

  14. Composite scintillators for detection of ionizing radiation

    DOEpatents

    Dai, Sheng [Knoxville, TN; Stephan, Andrew Curtis [Knoxville, TN; Brown, Suree S [Knoxville, TN; Wallace, Steven A [Knoxville, TN; Rondinone, Adam J [Knoxville, TN

    2010-12-28

    Applicant's present invention is a composite scintillator having enhanced transparency for detecting ionizing radiation comprising a material having optical transparency wherein said material comprises nano-sized objects having a size in at least one dimension that is less than the wavelength of light emitted by the composite scintillator wherein the composite scintillator is designed to have selected properties suitable for a particular application.

  15. Characteristics of High Latitude Ionosphere Scintillations

    NASA Astrophysics Data System (ADS)

    Morton, Y.

    2012-12-01

    As we enter a new solar maximum period, global navigation satellite systems (GNSS) receivers, especially the ones operating in high latitude and equatorial regions, are facing an increasing threat from ionosphere scintillations. The increased solar activities, however, also offer a great opportunity to collect scintillation data to characterize scintillation signal parameters and ionosphere irregularities. While there are numerous GPS receivers deployed around the globe to monitor ionosphere scintillations, most of them are commercial receivers whose signal processing mechanisms are not designed to operate under ionosphere scintillation. As a result, they may distort scintillation signal parameters or lose lock of satellite signals under strong scintillations. Since 2008, we have established and continuously improved a unique GNSS receiver array at HAARP, Alaska. The array contains high ends commercial receivers and custom RF front ends which can be automatically triggered to collect high quality GPS and GLONASS satellite signals during controlled heating experiments and natural scintillation events. Custom designed receiver signal tracking algorithms aim to preserve true scintillation signatures are used to process the raw RF samples. Signal strength, carrier phase, and relative TEC measurements generated by the receiver array since its inception have been analyzed to characterize high latitude scintillation phenomena. Daily, seasonal, and solar events dependency of scintillation occurrence, spectral contents of scintillation activities, and plasma drifts derived from these measurements will be presented. These interesting results demonstrate the feasibility and effectiveness of our experimental data collection system in providing insightful details of ionosphere responses to active perturbations and natural disturbances.

  16. Rejection of Alpha Surface Background in Non-scintillating Bolometric Detectors: The ABSuRD Project

    SciTech Connect

    Biassoni, M.; Brofferio, C.; Bucci, C.; Canonica, L.; di Vacri, M. L.; Gorla, P.; Pavan, M.; Yeh, M.

    2016-01-14

    Due to their excellent energy resolution values and the vast choice of possible materials, bolometric detectors are currently widely used in the physics of rare events. A limiting aspect for bolometers rises from their inability to discriminate among radiation types or surface from bulk events. It has been demonstrated that the main limitation to sensitivity for purely bolometric detectors is represented by surface alpha contaminations, causing a continuous background that cannot be discriminated. A new scintillation based technique for the rejection of surface alpha background in non- scintillating bolometric experiments is proposed in this work. The idea is to combine a scintillating and a high sensitivity photon detector with a non- scintillating absorber. Finally, we present results showing the possibility to reject events due to alpha decay at or nearby the surface of the crystal.

  17. Rejection of Alpha Surface Background in Non-scintillating Bolometric Detectors: The ABSuRD Project

    DOE PAGES

    Biassoni, M.; Brofferio, C.; Bucci, C.; ...

    2016-01-14

    Due to their excellent energy resolution values and the vast choice of possible materials, bolometric detectors are currently widely used in the physics of rare events. A limiting aspect for bolometers rises from their inability to discriminate among radiation types or surface from bulk events. It has been demonstrated that the main limitation to sensitivity for purely bolometric detectors is represented by surface alpha contaminations, causing a continuous background that cannot be discriminated. A new scintillation based technique for the rejection of surface alpha background in non- scintillating bolometric experiments is proposed in this work. The idea is to combinemore » a scintillating and a high sensitivity photon detector with a non- scintillating absorber. Finally, we present results showing the possibility to reject events due to alpha decay at or nearby the surface of the crystal.« less

  18. Melt-cast organic glasses as high-efficiency fast neutron scintillators

    SciTech Connect

    Carlson, Joseph S.; Feng, Patrick L.

    2016-06-24

    In this work we report a new class of organic-based scintillators that combines several of the desirable attributes of existing crystalline, liquid, and plastic organic scintillators. The prepared materials may be isolated in single crystalline form or melt-cast to produce highly transparent glasses that have been shown to provide high light yields of up to 16,000 photons/MeVee, as evaluated against EJ-200 plastic scintillators and solution-grown trans-stilbene crystals. The prepared organic glasses exhibit neutron/gamma pulse-shape discrimination (PSD) and are compatible with wavelength shifters to reduce optical self-absorption effects that are intrinsic to pure materials such as crystalline organics. In conclusion, the combination of high scintillation efficiency, PSD capabilities, and facile scale-up via melt-casting distinguishes this new class of amorphous materials from existing alternatives.

  19. Rejection of Alpha Surface Background in Non-scintillating Bolometric Detectors: The ABSuRD Project

    NASA Astrophysics Data System (ADS)

    Biassoni, M.; Brofferio, C.; Bucci, C.; Canonica, L.; di Vacri, M. L.; Gorla, P.; Pavan, M.; Yeh, M.

    2016-08-01

    Due to their excellent energy resolution values and the vast choice of possible materials, bolometric detectors are currently widely used in the physics of rare events. A limiting aspect for bolometers rises from their inability to discriminate among radiation types or surface from bulk events. It has been demonstrated that the main limitation to sensitivity for purely bolometric detectors is represented by surface alpha contaminations, causing a continuous background that cannot be discriminated. A new scintillation-based technique for the rejection of surface alpha background in non-scintillating bolometric experiments is proposed in this work. The idea is to combine a scintillating and a high sensitivity photon detector with a non-scintillating absorber. We present results showing the possibility to reject events due to alpha decay at or nearby the surface of the crystal.

  20. Melt-cast organic glasses as high-efficiency fast neutron scintillators

    SciTech Connect

    Carlson, Joseph S.; Feng, Patrick L.

    2016-06-24

    In this work we report a new class of organic-based scintillators that combines several of the desirable attributes of existing crystalline, liquid, and plastic organic scintillators. The prepared materials may be isolated in single crystalline form or melt-cast to produce highly transparent glasses that have been shown to provide high light yields of up to 16,000 photons/MeVee, as evaluated against EJ-200 plastic scintillators and solution-grown trans-stilbene crystals. The prepared organic glasses exhibit neutron/gamma pulse-shape discrimination (PSD) and are compatible with wavelength shifters to reduce optical self-absorption effects that are intrinsic to pure materials such as crystalline organics. In conclusion, the combination of high scintillation efficiency, PSD capabilities, and facile scale-up via melt-casting distinguishes this new class of amorphous materials from existing alternatives.

  1. Melt-cast organic glasses as high-efficiency fast neutron scintillators

    DOE PAGES

    Carlson, Joseph S.; Feng, Patrick L.

    2016-06-24

    In this work we report a new class of organic-based scintillators that combines several of the desirable attributes of existing crystalline, liquid, and plastic organic scintillators. The prepared materials may be isolated in single crystalline form or melt-cast to produce highly transparent glasses that have been shown to provide high light yields of up to 16,000 photons/MeVee, as evaluated against EJ-200 plastic scintillators and solution-grown trans-stilbene crystals. The prepared organic glasses exhibit neutron/gamma pulse-shape discrimination (PSD) and are compatible with wavelength shifters to reduce optical self-absorption effects that are intrinsic to pure materials such as crystalline organics. In conclusion, themore » combination of high scintillation efficiency, PSD capabilities, and facile scale-up via melt-casting distinguishes this new class of amorphous materials from existing alternatives.« less

  2. Synthesis of plastic scintillation microspheres: Evaluation of scintillators

    NASA Astrophysics Data System (ADS)

    Santiago, L. M.; Bagán, H.; Tarancón, A.; Garcia, J. F.

    2013-01-01

    The use of plastic scintillation microspheres (PSm) appear to be an alternative to liquid scintillation for the quantification of alpha and beta emitters because it does not generate mixed wastes after the measurement (organic and radioactive). In addition to routine radionuclide determinations, PSm can be used for further applications, e.g. for usage in a continuous monitoring equipment, for measurements of samples with a high salt concentration and for an extractive scintillation support which permits the separation, pre-concentration and measurement of the radionuclides without additional steps of elution and sample preparation. However, only a few manufacturers provide PSm, and the low number of regular suppliers reduces its availability and restricts the compositions and sizes available. In this article, a synthesis method based on the extraction/evaporation methodology has been developed and successfully used for the synthesis of plastic scintillation microspheres. Seven different compositions of plastic scintillation microspheres have been synthesised; PSm1 with polystyrene, PSm2 with 2,5-Diphenyloxazol(PPO), PSm3 with p-terphenyl (pT), PSm4 with PPO and 1,4-bis(5-phenyloxazol-2-yl) (POPOP), PSm5 pT and (1,4-bis [2-methylstyryl] benzene) (Bis-MSB), PSm6 with PPO, POPOP and naphthalene and PSm7 with pT, Bis-MSB and naphthalene. The synthesised plastic scintillation microspheres have been characterised in terms of their morphology, detection capabilities and alpha/beta separation capacity. The microspheres had a median diameter of approximately 130 μm. Maximum detection efficiency values were obtained for the PSm4 composition as follows 1.18% for 3H, 51.2% for 14C, 180.6% for 90Sr/90Y and 76.7% for 241Am. Values of the SQP(E) parameter were approximately 790 for PSm4 and PSm5. These values show that the synthesised PSm exhibit good scintillation properties and that the spectra are at channel numbers higher than in commercial PSm. Finally, the addition of

  3. Chloride, bromide and iodide scintillators with europium doping

    DOEpatents

    Zhuravleva, Mariya; Yang, Kan

    2014-08-26

    A halide scintillator material is disclosed where the halide may comprise chloride, bromide or iodide. The material is single-crystalline and has a composition of the general formula ABX.sub.3 where A is an alkali, B is an alkali earth and X is a halide which general composition was investigated. In particular, crystals of the formula ACa.sub.1-yEu.sub.yI.sub.3 where A=K, Rb and Cs were formed as well as crystals of the formula CsA.sub.1-yEu.sub.yX.sub.3 (where A=Ca, Sr, Ba, or a combination thereof and X=Cl, Br or I or a combination thereof) with divalent Europium doping where 0.ltoreq.y.ltoreq.1, and more particularly Eu doping has been studied at one to ten mol %. The disclosed scintillator materials are suitable for making scintillation detectors used in applications such as medical imaging and homeland security.

  4. Precision Crystal Calorimeters in High Energy Physics

    ScienceCinema

    Ren-Yuan Zhu

    2016-07-12

    Precision crystal calorimeters traditionally play an important role in high energy physics experiments. In the last two decades, it faces a challenge to maintain its precision in a hostile radiation environment. This paper reviews the performance of crystal calorimeters constructed for high energy physics experiments and the progress achieved in understanding crystal’s radiation damage as well as in developing high quality scintillating crystals for particle physics. Potential applications of new generation scintillating crystals of high density and high light yield, such as LSO and LYSO, in particle physics experiments is also discussed.

  5. Countering Beam Divergence Effects with Focused Segmented Scintillators for High DQE Megavoltage Active Matrix Imagers

    PubMed Central

    Liu, Langechuan; Antonuk, Larry E; Zhao, Qihua; El-Mohri, Youcef; Jiang, Hao

    2012-01-01

    The imaging performance of active matrix flat-panel imagers designed for megavoltage imaging (MV AMFPIs) is severely constrained by relatively low x-ray detection efficiency, which leads to a detective quantum efficiency (DQE) of only ~1%. Previous theoretical and empirical studies by our group have demonstrated the potential for addressing this constraint through utilization of thick, two-dimensional, segmented scintillators with optically isolated crystals. However, this strategy is constrained by degradation of high-frequency DQE resulting from spatial resolution loss at locations away from the central beam axis due to oblique incidence of radiation. To address this challenge, segmented scintillators constructed so that the crystals are individually focused toward the radiation source are proposed and theoretically investigated. The study was performed using Monte Carlo simulations of radiation transport to examine the modulation transfer function and DQE of focused segmented scintillators with thicknesses ranging from 5 to 60 mm. The results demonstrate that, independent of scintillator thickness, the introduction of focusing largely restores spatial resolution and DQE performance otherwise lost in thick, unfocused segmented scintillators. For the case of a 60 mm thick BGO scintillator and at a location 20 cm off the central beam axis, use of focusing improves DQE by up to a factor of ~130 at non-zero spatial frequencies. The results also indicate relatively robust tolerance of such scintillators to positional displacements, of up to 10 cm in the source-to-detector direction and 2 cm in the lateral direction, from their optimal focusing position, which could potentially enhance practical clinical use of focused segmented scintillators in MV AMFPIs. PMID:22854009

  6. Maximum likelihood positioning and energy correction for scintillation detectors

    NASA Astrophysics Data System (ADS)

    Lerche, Christoph W.; Salomon, André; Goldschmidt, Benjamin; Lodomez, Sarah; Weissler, Björn; Solf, Torsten

    2016-02-01

    An algorithm for determining the crystal pixel and the gamma ray energy with scintillation detectors for PET is presented. The algorithm uses Likelihood Maximisation (ML) and therefore is inherently robust to missing data caused by defect or paralysed photo detector pixels. We tested the algorithm on a highly integrated MRI compatible small animal PET insert. The scintillation detector blocks of the PET gantry were built with the newly developed digital Silicon Photomultiplier (SiPM) technology from Philips Digital Photon Counting and LYSO pixel arrays with a pitch of 1 mm and length of 12 mm. Light sharing was used to readout the scintillation light from the 30× 30 scintillator pixel array with an 8× 8 SiPM array. For the performance evaluation of the proposed algorithm, we measured the scanner’s spatial resolution, energy resolution, singles and prompt count rate performance, and image noise. These values were compared to corresponding values obtained with Center of Gravity (CoG) based positioning methods for different scintillation light trigger thresholds and also for different energy windows. While all positioning algorithms showed similar spatial resolution, a clear advantage for the ML method was observed when comparing the PET scanner’s overall single and prompt detection efficiency, image noise, and energy resolution to the CoG based methods. Further, ML positioning reduces the dependence of image quality on scanner configuration parameters and was the only method that allowed achieving highest energy resolution, count rate performance and spatial resolution at the same time.

  7. Radiation resistant composite scintillators based on Al2O3:Ti grains and their properties after irradiation

    NASA Astrophysics Data System (ADS)

    Galunov, N. Z.; Gorbacheva, T. E.; Grinyov, B. V.; Karavaeva, N. L.; Khabuseva, S. U.; Krech, A. V.; Levchuk, L. G.; Litvinov, L. A.; Popov, V. F.; Sorokin, P. V.

    2017-09-01

    The effect of irradiation on the scintillation light output, optical transmittance, and luminescent spectra of composite scintillators based on single crystal grains of Al2O3:Ti, is studied. The dielectric gel Sylgard-184 is the base and the binder for the grains inside the composite scintillator. The paper presents and analyses the results obtained for the scintillators exposed by 10 MeV electrons from the linear electron accelerator at room temperature. For exposure doses at least up to D ∼ 550 Mrad when dose rate is 1500 Mrad/h and D ∼ 125 Mrad when dose rate is 0.2 Mrad/h the composite scintillators are radiation-resistant.

  8. Extruded plastic scintillator for MINERvA

    SciTech Connect

    Pla-Dalmau, Anna; Bross, Alan D.; Rykalin, Victor V.; Wood, Brian M.; /NICADD, DeKalb

    2005-11-01

    An extrusion line has recently been installed at Fermilab in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new facility will serve to further develop and improve extruded plastic scintillator. Since polystyrene is widely used in the consumer industry, the logical path was to investigate the extrusion of commercial-grade polystyrene pellets with dopants to yield high quality plastic scintillator. The D0 and MINOS experiments are already using extruded scintillator strips in their detectors. A new experiment at Fermilab is pursuing the use of extruded plastic scintillator. A new plastic scintillator strip is being tested and its properties characterized. The initial results are presented here.

  9. Method of making a scintillator waveguide

    DOEpatents

    Bliss, Mary; Craig, Richard A.; Reeder, Paul L.

    2000-01-01

    The present invention is an apparatus for detecting ionizing radiation, having: a waveguide having a first end and a second end, the waveguide formed of a scintillator material wherein the therapeutic ionizing radiation isotropically generates scintillation light signals within the waveguide. This apparatus provides a measure of radiation dose. The apparatus may be modified to permit making a measure of location of radiation dose. Specifically, the scintillation material is segmented into a plurality of segments; and a connecting cable for each of the plurality of segments is used for conducting scintillation signals to a scintillation detector.

  10. SNO+ Scintillator Purification and Assay

    NASA Astrophysics Data System (ADS)

    Ford, R.; Chen, M.; Chkvorets, O.; Hallman, D.; Vázquez-Jáuregui, E.

    2011-04-01

    We describe the R&D on the scintillator purification and assay methods and technology for the SNO+ neutrino and double-beta decay experiment. The SNO+ experiment is a replacement of the SNO heavy water with liquid scintillator comprised of 2 g/L PPO in linear alkylbenzene (LAB). During filling the LAB will be transported underground by rail car and purified by multi-stage distillation and steam stripping at a flow rate of 19 LPM. While the detector is operational the scintillator can be recirculated at 150 LPM (full detector volume in 4 days) to provide repurification as necessary by either water extraction (for Ra, K, Bi) or by functional metal scavenger columns (for Pb, Ra, Bi, Ac, Th) followed by steam stripping to remove noble gases and oxygen (Rn, O2, Kr, Ar). The metal scavenger columns also provide a method for scintillator assay for ex-situ measurement of the U and Th chain radioactivity. We have developed "natural" radioactive spikes of Pb and Ra in LAB and use these for purification testing. Lastly, we present the planned operating modes and purification strategies and the plant specifications and design.

  11. SNO+ Scintillator Purification and Assay

    SciTech Connect

    Ford, R.; Vazquez-Jauregui, E.; Chen, M.; Chkvorets, O.; Hallman, D.

    2011-04-27

    We describe the R and D on the scintillator purification and assay methods and technology for the SNO+ neutrino and double-beta decay experiment. The SNO+ experiment is a replacement of the SNO heavy water with liquid scintillator comprised of 2 g/L PPO in linear alkylbenzene (LAB). During filling the LAB will be transported underground by rail car and purified by multi-stage distillation and steam stripping at a flow rate of 19 LPM. While the detector is operational the scintillator can be recirculated at 150 LPM (full detector volume in 4 days) to provide repurification as necessary by either water extraction (for Ra, K, Bi) or by functional metal scavenger columns (for Pb, Ra, Bi, Ac, Th) followed by steam stripping to remove noble gases and oxygen (Rn, O{sub 2}, Kr, Ar). The metal scavenger columns also provide a method for scintillator assay for ex-situ measurement of the U and Th chain radioactivity. We have developed ''natural'' radioactive spikes of Pb and Ra in LAB and use these for purification testing. Lastly, we present the planned operating modes and purification strategies and the plant specifications and design.

  12. Complex Dynamics of Equatorial Scintillation

    NASA Astrophysics Data System (ADS)

    Piersanti, Mirko; Materassi, Massimo; Forte, Biagio; Cicone, Antonio

    2017-04-01

    Radio power scintillation, namely highly irregular fluctuations of the power of trans-ionospheric GNSS signals, is the effect of ionospheric plasma turbulence. The scintillation patterns on radio signals crossing the medium inherit the ionospheric turbulence characteristics of inter-scale coupling, local randomness and large time variability. On this basis, the remote sensing of local features of the turbulent plasma is feasible by studying radio scintillation induced by the ionosphere. The distinctive character of intermittent turbulent media depends on the fluctuations on the space- and time-scale statistical properties of the medium. Hence, assessing how the signal fluctuation properties vary under different Helio-Geophysical conditions will help to understand the corresponding dynamics of the turbulent medium crossed by the signal. Data analysis tools, provided by complex system science, appear to be best fitting to study the response of a turbulent medium, as the Earth's equatorial ionosphere, to the non-linear forcing exerted by the Solar Wind (SW). In particular we used the Adaptive Local Iterative Filtering, the Wavelet analysis and the Information theory data analysis tool. We have analysed the radio scintillation and ionospheric fluctuation data at low latitude focusing on the time and space multi-scale variability and on the causal relationship between forcing factors from the SW environment and the ionospheric response.

  13. Characterization of GAGG:Ce scintillators with various Al-to-Ga ratio

    NASA Astrophysics Data System (ADS)

    Sibczynski, Pawel; Iwanowska-Hanke, Joanna; Moszyński, Marek; Swiderski, Lukasz; Szawłowski, Marek; Grodzicka, Martyna; Szczęśniak, Tomasz; Kamada, Kei; Yoshikawa, Akira

    2015-02-01

    We have studied the scintillation properties of cerium doped gadolinium aluminum gallium garnet (GAGG:Ce) scintillators with various Al-to-Ga ratio. Having many advantages, like high density (6.63 g/cm3), high light output, fair energy resolution and quite fast decay time, the scintillators are an excellent solution for gamma rays detection. In this paper performance of the GAGG:1%Ce crystals with different Al-to-Ga ratios is presented. The study covered measurements of emission spectra, light output, energy resolution and non-proportionality for each crystal. It was observed that the light output of the recently obtainable crystals varies from 40,000 to 55,000 ph/MeV. Maximum emission wavelength of about 520 nm promotes silicon based photodetectors for use with these scintillators. The best energy resolution of 3.7% at 662 keV, measured with Hamamatsu S8664-1010 APD, was obtained for the sample with the minimum gallium content. This result is close to these obtained with the group of scintillators retaining very good energy resolution, like LaCl3 and CeBr3.

  14. Radiopure ZnMoO4 scintillating bolometers for the LUMINEU double-beta experiment

    NASA Astrophysics Data System (ADS)

    Poda, D. V.; Armengaud, E.; Arnaud, Q.; Augier, C.; Barabash, A. S.; Benoît, A.; Benoît, A.; Bergé, L.; Boiko, R. S.; Bergmann, T.; Blümer, J.; Broniatowski, A.; Brudanin, V.; Camus, P.; Cazes, A.; Censier, B.; Chapellier, M.; Charlieux, F.; Chernyak, D. M.; Coron, N.; Coulter, P.; Cox, G. A.; Danevich, F. A.; de Boissière, T.; Decourt, R.; De Jesus, M.; Devoyon, L.; Drillien, A.-A.; Dumoulin, L.; Eitel, K.; Enss, C.; Filosofov, D.; Fleischmann, A.; Fourches, N.; Gascon, J.; Gastaldo, L.; Gerbier, G.; Giuliani, A.; Gros, M.; Hehn, L.; Henry, S.; Hervé, S.; Heuermann, G.; Humbert, V.; Ivanov, I. M.; Juillard, A.; Kéfélian, C.; Kleifges, M.; Kluck, H.; Kobychev, V. V.; Koskas, F.; Kozlov, V.; Kraus, H.; Kudryavtsev, V. A.; Le Sueur, H.; Loidl, M.; Magnier, P.; Makarov, E. P.; Mancuso, M.; de Marcillac, P.; Marnieros, S.; Marrache-Kikuchi, C.; Menshikov, A.; Nasonov, S. G.; Navick, X.-F.; Nones, C.; Olivieri, E.; Pari, P.; Paul, B.; Penichot, Y.; Pessina, G.; Piro, M. C.; Plantevin, O.; Redon, T.; Robinson, M.; Rodrigues, M.; Rozov, S.; Sanglard, V.; Schmidt, B.; Shlegel, V. N.; Siebenborn, B.; Strazzer, O.; Tcherniakhovski, D.; Tenconi, M.; Torres, L.; Tretyak, V. I.; Vagneron, L.; Vasiliev, Ya. V.; Velazquez, M.; Viraphong, O.; Walker, R. J.; Weber, M.; Yakushev, E.; Zhang, X.; Zhdankov, V. N.

    2015-08-01

    The results of R&D of radiopure zinc molybdate (ZnMoO4) based scintillating bolometers for the LUMINEU (Luminescent Underground Molybdenum Investigation for NEUtrino mass and nature) double-beta decay experiment are presented. A dedicated two-stage molybdenum purification technique (sublimation in vacuum and recrystallization from aqueous solutions) and an advanced directional solidification method (the low-thermal-gradient Czochralski technique) were utilized to produce high optical quality large mass (˜1 kg) ZnMoO4 crystal boules and first 100Mo (99.5%) enriched Zn100MoO4 crystal scintillator (mass of ˜0.2 kg). Scintillating bolometers based on ZnMoO4 (≈ 0.33 kg) and Zn100MoO4 (≈ 0.06 kg) scintillation elements and high purity Ge wafers were tested in the EDELWEISS set-up at the Modane Underground Laboratory (France). Long term low temperature tests demonstrate excellent detectors' performance and effectiveness of the purification and solidification procedures for the achievement of high radiopurity of the material, in particular with a bulk activity of 228Th and 226Ra below 4 µBq/kg. The adopted protocol was used to produce for the first time a large volume Zn100MoO4 crystal scintillator (mass of ˜1.4 kg, 100Mo enrichment is 99.5%) to search for neutrinoless double-beta decay of 100Mo in the framework of the LUMINEU project.

  15. Timing resolution of scintillation-detector systems: a Monte Carlo analysis

    PubMed Central

    Choong, Woon-Seng

    2010-01-01

    Recent advancements in fast scintillating materials and fast photomultiplier tubes (PMTs) have stimulated renewed interest in time-of-flight (TOF) positron emission tomography (PET). It is well known that the improvement in the timing resolution in PET can significantly reduce the noise variance in the reconstructed image resulting in improved image quality. In order to evaluate the timing performance of scintillation detectors used in TOF PET, we use a Monte Carlo analysis to model the physical processes (crystal geometry, crystal surface finish, scintillator rise time, scintillator decay time, photoelectron yield, PMT transit time spread, PMT single-electron response, amplifier response, and time pick-off method) that can contribute to the timing resolution of scintillation-detector systems. In the Monte Carlo analysis, the photoelectron emissions are modeled by a rate function, which is used to generate the photoelectron time points. The rate function, which is simulated using Geant4, represents the combined intrinsic light emissions of the scintillator and the subsequent light transport through the crystal. The PMT output signal is determined by the superposition of the PMT single-electron response resulting from the photoelectron emissions. The transit time spread and the single-electron gain variation of the PMT are modeled in the analysis. Three practical time pick-off methods are considered in the analysis. Statistically, the best timing resolution is achieved with the first photoelectron timing. The calculated timing resolution suggests that a leading edge discriminator gives better timing performance than a constant fraction discriminator and produces comparable results when a 2-threshold or 3-threshold discriminator is used. For a typical PMT, the effect of detector noise on the timing resolution is negligible. The calculated timing resolution is found to improve with increasing mean photoelectron yield, decreasing scintillator decay time, and decreasing

  16. Characterization of a ZnSe scintillating bolometer prototype for neutrinoless double beta decay search

    NASA Astrophysics Data System (ADS)

    Tenconi, M.; Giuliani, A.; Nones, C.; Pessina, G.; Plantevin, O.; Rusconi, C.

    2014-01-01

    As proposed in the LUCIFER project, ZnSe crystals are attractive materials to realize scintillating bolometers aiming at the search for neutrinoless double beta decay of the promising isotope 82Se. However, the optimization of the ZnSe-based detectors is rather complex and requires a wide-range investigation of the crystal features: optical properties, crystalline quality, scintillation yields and bolometric behaviour. Samples tested up to now show problems in the reproducibility of crucial aspects of the detector performance. In this work, we present the results obtained with a scintillating bolometer operated aboveground at about 25 mK. The detector energy absorber was a single 1 cm3 ZnSe crystal. The good energy resolution of the heat channel (about 14 keV at 1460 keV) and the excellent alpha/beta discrimination capability are very encouraging for a successful realization of the LUCIFER program. The bolometric measurements were completed by optical tests on the crystal (optical transmission and luminescence measurements down to 10 K) and investigation of the crystalline structure. The work here described provides a set of parameters and procedures useful for a complete pre-characterization of ZnSe crystals in view of the realization of highly performing scintillating bolometers.

  17. Mercuric Iodide Photocell Technology for Room Temperature Readout of Scintillators

    SciTech Connect

    Warnick Kernan et al.

    2007-08-31

    Mercuric iodide (HgI2) is a well known material for the direct detection of gamma rays; however, the largest volume achievable is limited by thickness of the detector, which needs to be a small fraction of the average trapping length for electrons. We are reporting here preliminary results in using HgI2 crystals to fabricate photocells used in the readout of various scintillators. The optical spectral response and efficiency of these photocells were measured and will be reported. Preliminary nuclear response from a HgI2 photocell that was optically matched to a Ce3+ :LaBr3 scintillator will also be presented and discussed. Further improvements will be sought by optimizing the transparent contact technology.

  18. Radiation imaging with a new scintillator and a CMOS camera

    NASA Astrophysics Data System (ADS)

    Kurosawa, S.; Shoji, Y.; Pejchal, J.; Yokota, Y.; Yoshikawa, A.

    2014-07-01

    A new imaging system consisting of a high-sensitivity complementary metal-oxide semiconductor (CMOS) sensor, a microscope and a new scintillator, Ce-doped Gd3(Al,Ga)5O12 (Ce:GAGG) grown by the Czochralski process, has been developed. The noise, the dark current and the sensitivity of the CMOS camera (ORCA-Flash4.0, Hamamatsu) was revised and compared to a conventional CMOS, whose sensitivity is at the same level as that of a charge coupled device (CCD) camera. Without the scintillator, this system had a good position resolution of 2.1 ± 0.4 μm and we succeeded in obtaining the alpha-ray images using 1-mm thick Ce:GAGG crystal. This system can be applied for example to high energy X-ray beam profile monitor, etc.

  19. FLARES: A flexible scintillation light apparatus for rare event searches

    NASA Astrophysics Data System (ADS)

    Sisti, M.; Baldazzi, G.; Bonvicini, V.; Campana, R.; Capelli, S.; Evangelista, Y.; Feroci, M.; Fuschino, F.; Gironi, L.; Labanti, C.; Marisaldi, M.; Previtali, E.; Rignanese, L.; Rachevsky, A.; Vacchi, A.; Zampa, G.; Zampa, N.; Zuffa, M.

    2016-07-01

    FLARES is a project for an innovative detector technology to be applied to rare event searches, and in particular to neutrinoless double beta decay experiments. Its novelty is the enhancement and optimization of the collection of the scintillation light emitted by ultra-pure crystals through the use of arrays of high performance silicon photodetectors cooled to 120 K. This would provide scintillation detectors with 1% level energy resolution, with the advantages of a technology offering relatively simple low cost mass scalability and powerful background reduction handles, as requested by future neutrinoless double beta decay experimental programs. The performances of a first production of matrices of Silicon Drift Detectors are presented and discussed in this paper.

  20. An apparatus for studying scintillator properties at high isostatic pressures

    SciTech Connect

    Gaume, R. M.; Lam, S.; Gascon, M.; Feigelson, R. S.; Setyawan, W.; Curtarolo, S.

    2013-01-15

    We describe the design and operation of a unique hydraulic press for the study of scintillator materials under isostatic pressure. This press, capable of developing a pressure of a gigapascal, consists of a large sample chamber pressurized by a two-stage hydraulic amplifier. The optical detection of the scintillation light emitted by the sample is performed, through a large aperture optical port, by a photodetector located outside the pressure vessel. In addition to providing essential pressure-dependent studies on the emission characteristics of radioluminescent materials, this apparatus is being developed to elucidate the mechanisms behind the recently observed dependency of light-yield nonproportionality on electronic band structure. The variation of the light output of a Tl:CsI crystal under 511-keV gamma excitation and hydrostatic pressure is given as an example.

  1. Scintillation properties of LuI 3:Ce

    NASA Astrophysics Data System (ADS)

    Glodo, J.; Shah, K. S.; Klugerman, M.; Wong, P.; Higgins, B.; Dorenbos, P.

    2005-01-01

    Lutetium iodide (LuI3) is a new addition to the family of Ce-doped lanthanide trihalide scintillating materials. Crystals of this material show hexagonal structure with density of 5.6 g/cm3 and have been grown by the Bridgman method. Under X-ray excitation this material exhibits broad, cerium based emission that peaks at 475 and 520 nm. The fastest and major component of scintillation time profile of LuI3:Ce emission decays with a 31 ns time constant. The light yield of LuI3:Ce for thin samples (∼0.2 mm) was estimated to be ∼50,000 photons/MeV.

  2. LiCaAlF6 scintillators in neutron and gamma radiation fields

    NASA Astrophysics Data System (ADS)

    Viererbl, L.; Klupák, V.; Vinš, M.; Koleška, M.; Šoltés, J.; Yoshikawa, A.; Nikl, M.

    2016-09-01

    Intentionally doped LiCaAlF6 (LiCAF) single crystals are prospective scintillators, especially for thermal neutron detection through the 6Li(n,t)4He nuclear reaction. Four different LiCAF scintillator samples were tested in various neutron and gamma fields. Two of the tested samples were LiCAF:Eu and LiCAF:Eu,Na single crystals, and another two samples were made of LiCAF:Eu micro crystals dispersed in transparent rubber, with different rubber dimensions. All LiCAF samples contain lithium enriched to6Li. A plutonium-beryllium source was used as a neutron source. The neutron spectrum was modified by moderator and filter to get different ratios between thermal, epithermal and fast neutron fluence rates. The MCNP code was used for calculations of the fluence rates for different configurations. Radionuclides 137Cs and 60Co were applied as gamma radiation sources. The light signal from the scintillator was evaluated with a photomultiplier and a multichannel analyzer. The purpose of this work was to study the characteristics of LiCAF scintillators, especially the ability to discriminate signals from neutron and gamma radiation, which is the basic scintillator condition for neutron detection in mixed neutron-gamma radiation fields. Generally, the discrimination can be done by the pulse height and/or the pulse shape of the evaluated signals. Both methods can be used for a LiCAF scintillator. However, only the pulse height discrimination method is discussed in this paper. The possibility of fast neutron detection with LiCAF scintillators was also tested.

  3. Polycrystalline scintillators for large area detectors in HEP experiments

    NASA Astrophysics Data System (ADS)

    Dosovitskiy, G.; Fedorov, A.; Karpyuk, P.; Kuznetsova, D.; Mikhlin, A.; Kozlov, D.; Dosovitskiy, A.; Korjik, M.

    2017-06-01

    After significant increase of the accelerator luminosity throughout the High Luminosity phase of LHC, charged hadrons and neutrons with fluences higher than 1014 p/cm2 per year in the largest pseudo-rapidity regions of the detectors will cause increased radiation damage of materials. Increasing activation of the experimental equipment will make periodical maintenance and replacement of detector components difficult. Therefore, the selected materials for new detectors should be tolerant to radiation damage. Y3Al5O12:Ce (YAG:Ce) crystal was found to be one of the most radiation hard scintillation materials. However, production of YAG:Ce in a single crystalline form is costly, because crystal growth is performed at temperature near 1900°C with a very low rate of transformation of a raw material into a crystal. We propose translucent YAG:Ce ceramics as an alternative cheaper solution. Ceramic samples were sintered up to density ~98% of the theoretical value and were translucent. The samples have demonstrated light yield of 2200 phot./MeV under 662 keV γ-quanta, which gives the expected response to minimum ionizing particle around 3000 phot. for 2 mm thick plate. Scintillation light yield, registered under surface layer excitation with α-particles, was 50-70% higher than for the reference single crystal YAG:Ce.

  4. SrI2 scintillator for gamma ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Cherepy, N. J.; Sturm, B. W.; Drury, O. B.; Hurst, T. A.; Sheets, S. A.; Ahle, L. E.; Saw, C. K.; Pearson, M. A.; Payne, S. A.; Burger, A.; Boatner, L. A.; Ramey, J. O.; van Loef, E. V.; Glodo, J.; Hawrami, R.; Higgins, W. M.; Shah, K. S.; Moses, W. W.

    2009-08-01

    We are working to perfect the growth of divalent Eu-doped strontium iodide single crystals and to optimize the design of SrI2(Eu)-based gamma ray spectrometers. SrI2(Eu) offers a light yield in excess of 100,000 photons/MeV and light yield proportionality surpassing that of Ce-doped lanthanum bromide. Thermal and x-ray diffraction analyses of SrI2 and EuI2 indicate an excellent match in melting and crystallographic parameters, and very modest thermal expansion anisotropy. We have demonstrated energy resolution with SrI2(4-6%Eu) of 2.6% at 662 keV and 7.6% at 60 keV with small crystals, while the resolution degrades somewhat for larger sizes. Our experiments suggest that digital techniques may be useful in improving the energy resolution in large crystals impaired by light-trapping, in which scintillation light is re-absorbed and re-emitted in large and/or highly Eu2+ -doped crystals. The light yield proportionality of SrI2(Eu) is found to be superior to that of other known scintillator materials, such as LaBr3(Ce) and NaI(Tl).

  5. A neutron scintillator based on transparent nanocrystalline CaF{sub 2}:Eu glass ceramic

    SciTech Connect

    Struebing, Christian; Kang, Zhitao; Chong, JooYun; Wagner, Brent; Lee, Gyuhyon; Ding, Yong; Zavala, Martin; Erickson, Anna; Wang, Cai-Lin; Diawara, Yacouba; Engels, Ralf

    2016-04-11

    There are no efficient Eu{sup 2+} doped glass neutron scintillators reported due to low doping concentrations of Eu{sup 2+} and the amorphous nature of the glass matrix. In this work, an efficient CaF{sub 2}:Eu glass ceramic neutron scintillator was prepared by forming CaF{sub 2}:Eu nanocrystals in a {sup 6}Li-containing glass matrix. Through appropriate thermal treatments, the scintillation light yield of the transparent glass ceramic was increased by a factor of at least 46 compared to the as-cast amorphous glass. This improvement was attributed to more efficient energy transfer from the CaF{sub 2} crystals to the Eu{sup 2+} emitting centers. Further light yield improvement is expected if the refractive index of the glass matrix can be matched to the CaF{sub 2} crystal.

  6. LaCl{sub 3}:Ce scintillator for Gamma ray detection

    SciTech Connect

    Shah, K.S.; Glodo, J.; Klugerman, M.; Cirignano, L.; Moses, W.W.; Derenzo, S.E.; Weber, M.J.

    2002-05-25

    In this paper, we report on a relatively new cerium doped scintillator - LaCl3 for gamma ray spectroscopy. Crystals of this scintillator have been grown using Bridgman method. This material when doped with 10 percent cerium has high light output ({approx} 50,000 photons/MeV) and fast principal decay time constant ({approx}20 ns). Furthermore, it shows excellent energy resolution for gamma ray detection. For example, energy resolution as low as 3.2 percent (FWHM) has been achieved with 662 keV photons (137Cs source) at room temperature. Also high timing resolution (264 ps - FWHM) has been recorded with LaCl3-PMT and BaF2-PMT detectors operating in coincidence using 511 keV positron annihilation gamma ray pairs. Details of crystal growth, scintillation properties, and variation of these properties with cerium concentration are also reported.

  7. Scintillation properties of selected oxide monocrystals activated with Ce and Pr

    NASA Astrophysics Data System (ADS)

    Wojtowicz, Andrzej J.; Drozdowski, Winicjusz; Wisniewski, Dariusz; Lefaucheur, Jean-Luc; Galazka, Zbigniew; Gou, Zhenhui; Lukasiewicz, Tadeusz; Kisielewski, Jaroslaw

    2006-01-01

    In the last 10-15 years there has been a significant effort toward development of new, more efficient and faster materials for detection of ionizing radiation. A growing demand for better scintillator crystals for detection of 511 keV gamma particles has been due mostly to recent advances in modern imaging systems employing positron emitting radionuclides for medical diagnostics in neurology, oncology and cardiology. While older imaging systems were almost exclusively based on BGO and NaI:Tl crystals the new systems, e.g., ECAT Accel, developed by Siemens/CTI, are based on recently discovered and developed LSO (Lu 2SiO 5:Ce, Ce-activated lutetium oxyorthosilicate) crystals. Interestingly, despite very good properties of LSO, there still is a strong drive toward development of new scintillator crystals that would show even better performance and characteristics. In this presentation we shall review spectroscopic and scintillator characterization of new complex oxide crystals, namely LSO, LYSO, YAG, LuAP (LuAlO 3, lutetium aluminate perovskite) and LuYAP activated with Ce and Pr. The LSO:Ce crystals have been grown by CTI Inc (USA), LYSO:Ce, LuAP:Ce and LuYAP:Ce crystals have been grown by Photonic Materials Ltd., Scotland (PML is the only company providing large LuAP:Ce crystals on a commercial scale), while YAG:Pr and LuAP:Pr crystals have been grown by Institute of Electronic Materials Technology (Poland). All these crystals have been characterized at Institute of Physics, N. Copernicus University (Poland). We will review and compare results of measurements of radioluminescence, VUV spectroscopy, scintillation light yields, scintillation time profiles and low temperature thermoluminescence performed on these crystals. We will demonstrate that all experiments clearly indicate that there is a significant room for improvement of LuAP, LuYAP and YAG. While both Ce-activated LSO and LYSO perform very well, we also note that LuYAP:Ce, LuAP:Ce and YAG:Pr offer some

  8. The lower timing resolution bound for scintillators with non-negligible optical photon transport time in time-of-flight PET

    PubMed Central

    Vinke, Ruud; Olcott, Peter D.; Cates, Joshua W.; Levin, Craig S.

    2014-01-01

    In this work, a method is presented that can calculate the lower bound of the timing resolution for large scintillation crystals with non-negligible photon transport. Hereby, the timing resolution bound can directly be calculated from Monte Carlo generated arrival times of the scintillation photons. This method extends timing resolution bound calculations based on analytical equations, as crystal geometries can be evaluated that do not have closed form solutions of arrival time distributions. The timing resolution bounds are calculated for an exemplary 3 × 3 × 20 mm3 LYSO crystal geometry, with scintillation centers exponentially spread along the crystal length as well as with scintillation centers at fixed distances from the photosensor. Pulse shape simulations further show that analog photosensors intrinsically operate near the timing resolution bound, which can be attributed to the finite single photoelectron pulse rise time. PMID:25255807

  9. Cosmic ray scintillations. II - General theory of interplanetary scintillations

    NASA Technical Reports Server (NTRS)

    Owens, A. J.

    1974-01-01

    The motion of charged particles in a stochastic magnetic field with nonzero mean is considered via a generalized quasi-linear expansion of Liouville's equation. The general result is an equation relating cosmic ray scintillations to magnetic fluctuations and to cosmic ray gradients. The resonant interaction between particles and the random magnetic field is considered in detail, and the effect of nonlinear terms in the equations is considered. The nonlinear terms are important in damping out initial conditions and in determining conditions near cyclotron resonances. The application of the theory to the propagation of cosmic rays during quiet times in interplanetary space is considered. It is concluded that cosmic ray scintillations in interplanetary space may provide useful information about interplanetary particles and fields and also about nonlinear plasma interactions.

  10. The observation of scintillation in a hydrated inorganic compound: CeCl3 6H2O

    SciTech Connect

    Boatner, Lynn A; Neal, John S; Ramey, Joanne Oxendine; Chakoumakos, Bryan C; Custelcean, Radu

    2013-01-01

    We have recently reported the discovery of a new family of rare-earth metal-organic single-crystal scintillators based on Ce3+ as the activator ion. Starting with the CeCl3(CH3OH)4 prototype, this family of scintillators has recently been extended to include complex metal-organic adducts produced by reacting CeCl3 with heavier organics (e.g., isomers of propanol and butanol). Some of these new rare-earth metal-organic materials incorporated waters of hydration in their structures, and the observation of scintillation in these hydrated compounds was an original finding for any solid scintillator. In the present work, we now report what is apparently the initial observation of gamma-ray-excited scintillation in an inorganic hydrated material, namely single-crystal monoclinic CeCl3 6H2O. This observation shows that the mechanisms of the various scintillation energy-transfer processes are not blocked by the presence of waters of hydration in an inorganic material and that the observation of scintillation in other hydrated inorganic compounds is not precluded.

  11. Comparative Gamma Spectroscopy with SrI2(Eu), GYGAG(Ce) and Bi-loaded Plastic Scintillators

    SciTech Connect

    Cherepy, Nerine; Payne, Stephen A.; Sturm, Benjamin; Kuntz, Joshua; Seeley, Zachary; Rupert, B. L.; Sanner, Robert; Drury, Owen; Hurst, T.; Fisher, S E; Groza, Michael; Matei, L.; Burger, Arnold; Hawrami, Rastgo; Shah, Kanai; Boatner, Lynn A

    2011-01-01

    We are developing new scintillator materials that offer potential for high resolution gamma ray spectroscopy at low cost. Single crystal SrI2(Eu) offers ~3% resolution at 662 keV, in sizes of ~1 in3. We have developed ceramics processing technology allowing us to achieve cubic inch scale transparent ceramic scintillators offering gamma spectroscopy performance superior to NaI(Tl). We fabricated a bismuth-loaded plastic scintillator that demonstrates energy resolution of ~8% at 662 keV in small sizes.

  12. Development of novel growth methods for halide single crystals

    NASA Astrophysics Data System (ADS)

    Yokota, Yuui; Kurosawa, Shunsuke; Shoji, Yasuhiro; Ohashi, Yuji; Kamada, Kei; Yoshikawa, Akira

    2017-03-01

    We developed novel growth methods for halide scintillator single crystals with hygroscopic nature, Halide micro-pulling-down [H-μ-PD] method and Halide Vertical Bridgman [H-VB] method. The H-μ-PD method with a removable chamber system can grow a single crystal of halide scintillator material with hygroscopicity at faster growth rate than the conventional methods. On the other hand, the H-VB method can grow a large bulk single crystal of halide scintillator without a quartz ampule. CeCl3, LaBr3, Ce:LaBr3 and Eu:SrI2 fiber single crystals could be grown by the H-μ-PD method and Eu:SrI2 bulk single crystals of 1 and 1.5 inch in diameter could be grown by the H-VB method. The grown fiber and bulk single crystals showed comparable scintillation properties to the previous reports using the conventional methods.

  13. Improved lithium iodide neutron scintillator with Eu2+ activation: The elimination of Suzuki-Phase precipitates

    NASA Astrophysics Data System (ADS)

    Boatner, L. A.; Comer, E. P.; Wright, G. W.; Ramey, J. O.; Riedel, R. A.; Jellison, G. E.; Kolopus, J. A.

    2017-05-01

    Monovalent alkali halides such as NaI, CsI, and LiI are widely used as inorganic scintillators for radiation detection due to their light yield, the capability for the growth of large single crystals, relatively low cost, and other favorable characteristics. These materials are frequently activated through the addition of small amounts (e.g., a few hundred ppm) of elements such as thallium - or sodium in the case of CsI. The monovalent alkali halide scintillators can also be activated with low concentrations of Eu2+, however Eu activation has previously not been widely employed due to the non-uniform segregation of the divalent Eu dopant that leads to the formation of unwanted phases during Bridgman or other solidification crystal-growth methods. Specifically, for Eu concentrations near and above 0.5%, Suzuki Phase precipitates form in the course of the melt-growth process, and these Suzuki Phase particles scatter the scintillation light. This adversely affects the scintillator performance via reduction in the optical transmission of the material, and depending on the crystal thickness and precipitated-particle concentration, this reduction can occur up to the point of opacity. Here we describe a post-growth process for the removal of Suzuki Phase precipitates from single crystals of the neutron scintillator LiI activated with Eu2+ at concentrations up to and in excess of 3 wt%, and we correlate the resulting neutron-detection performance with the thermal processing methods used to remove the Suzuki Phase particles. The resulting improved scintillator properties using increased Eu activator levels are applicable to neutron imaging and active interrogation systems, and pulse-height gamma-ray spectroscopy rather than pulse-shape discrimination can be used to discriminate between gamma ray and neutron interaction events.

  14. Improved lithium iodide neutron scintillator with Eu2+ activation: The elimination of Suzuki-Phase precipitates

    DOE PAGES

    Boatner, Lynn A.; Comer, Eleanor P.; Wright, Gomez W.; ...

    2017-02-21

    Monovalent alkali halides such as NaI, CsI, and LiI are widely used as inorganic scintillators for radiation detection due to their light yield, the capability for the growth of large single crystals, relatively low cost, and other favorable characteristics. These materials are frequently activated through the addition of small amounts (e.g., a few hundred ppm) of elements such as thallium - or sodium in the case of CsI. The monovalent alkali halide scintillators can also be activated with low concentrations of Eu2+, however Eu activation has previously not been widely employed due to the non-uniform segregation of the divalent Eumore » dopant that leads to the formation of unwanted phases during Bridgman or other solidification crystal-growth methods. Specifically, for Eu concentrations near and above ~0.5%, Suzuki Phase precipitates form in the course of the melt-growth process, and these Suzuki Phase particles scatter the scintillation light. This adversely affects the scintillator performance via reduction in the optical transmission of the material, and depending on the crystal thickness and precipitated-particle concentration, this reduction can occur up to the point of opacity. Here we describe a post-growth process for the removal of Suzuki Phase precipitates from single crystals of the neutron scintillator LiI activated with Eu2+ at concentrations up to and in excess of 3 wt.%, and we correlate the resulting neutron-detection performance with the thermal processing methods used to remove the Suzuki Phase particles. Furthermore, the resulting improved scintillator properties using increased Eu activator levels are applicable to neutron imaging and active interrogation systems, and pulse-height gamma-ray spectroscopy rather than pulse-shape discrimination can be used to discriminate between gamma ray and neutron interaction events.« less

  15. Predicting the timing properties of phosphor-coated scintillators using Monte Carlo light transport simulation

    PubMed Central

    Roncali, Emilie; Schmall, Jeffrey P.; Viswanath, Varsha; Berg, Eric; Cherry, Simon R.

    2014-01-01

    Current developments in positron emission tomography (PET) focus on improving timing performance for scanners with time-of-flight (TOF) capability, and incorporating depth-of-interaction (DOI) information. Recent studies have shown that incorporating DOI correction in TOF detectors can improve timing resolution, and that DOI also becomes more important in long axial field-of-view scanners. We have previously reported the development of DOI-encoding detectors using phosphor-coated scintillation crystals; here we study the timing properties of those crystals to assess the feasibility of providing some level of DOI information without significantly degrading the timing performance. We used Monte Carlo simulations to provide a detailed understanding of light transport in phosphor-coated crystals which cannot be fully characterized experimentally. Our simulations used a custom reflectance model based on 3D crystal surface measurements. Lutetium oxyorthosilicate (LSO) crystals were simulated with a phosphor coating in contact with the scintillator surfaces and an external diffuse reflector (teflon). Light output, energy resolution, and pulse shape showed excellent agreement with experimental data obtained on 3 × 3 × 10 mm3 crystals coupled to a photomultiplier tube (PMT). Scintillator intrinsic timing resolution was simulated with head-on and side-on configurations, confirming the trends observed experimentally. These results indicate that the model may be used to predict timing properties in phosphor-coated crystals and guide the coating for optimal DOI resolution/timing performance trade-off for a given crystal geometry. Simulation data suggested that a time stamp generated from early photoelectrons minimizes degradation of the timing resolution, thus making this method potentially more useful for TOF-DOI detectors than our initial experiments suggested. Finally, this approach could easily be extended to the study of timing properties in other scintillation crystals

  16. Modeling and Investigation of Heavy Oxide and Alkali-Halide Scintillators for Potential Use in Neutron and Gamma Detection Systems

    DTIC Science & Technology

    2015-06-01

    INVESTIGATION OF HEAVY OXIDE AND ALKALI -HALIDE SCINTILLATORS FOR POTENTIAL USE IN NEUTRON AND GAMMA DETECTION SYSTEMS by Jeremy S. Cadiente June...AND ALKALI - HALIDE SCINTILLATORS FOR POTENTIAL USE IN NEUTRON AND GAMMA DETECTION SYSTEMS 5. FUNDING NUMBERS 6. AUTHOR(S) Jeremy S. Cadiente 7...CODE 13. ABSTRACT (maximum 200 words) Heavy inorganic oxide and alkali -halide crystals, which previous experimental research has indicated to have

  17. Scintillation Monitoring Using Asymmetry Index

    NASA Astrophysics Data System (ADS)

    Shaikh, Muhammad Mubasshir; Mahrous, Ayman; Abdallah, Amr; Notarpietro, Riccardo

    Variation in electron density can have significant effect on GNSS signals in terms of propagation delay. Ionospheric scintillation can be caused by rapid change of such delay, specifically, when they last for a longer period of time. Ionospheric irregularities that account for scintillation may vary significantly in spatial range and drift with the background plasma at speeds of 45 to 130 m/sec. These patchy irregularities may occur several times during night, e.g. in equatorial region, with the patches move through the ray paths of the GNSS satellite signals. These irregularities are often characterized as either ‘large scale’ (which can be as large as several hundred km in East-West direction and many times that in the North-South direction) or ‘small scale’ (which can be as small as 1m). These small scale irregularities are regarded as the main cause of scintillation [1,2]. In normal solar activity conditions, the mid-latitude ionosphere is not much disturbed. However, during severe magnetic storms, the aurora oval extends towards the equator and the equator anomaly region may stretched towards poles extending the scintillation phenomena more typically associated with those regions into mid-latitudes. In such stormy conditions, the predicted TEC may deviate largely from the true value of the TEC both at low and mid-latitudes due to which GNSS applications may be strongly degraded. This work is an attempt to analyze ionospheric scintillation (S4 index) using ionospheric asymmetry index [3]. The asymmetry index is based on trans-ionospheric propagation between GPS and LEO satellites in a radio occultation (RO) scenario, using background ionospheric data provided by MIDAS [4]. We attempted to simulate one of the recent geomagnetic storms (NOAA scale G4) occurred over low/mid-latitudes. The storm started on 26 September 2011 at UT 18:00 and lasted until early hours of 27 September 2011. The scintillation data for the storm was taken from an ionospheric

  18. LHCb Upgrade: Scintillating Fibre Tracker

    NASA Astrophysics Data System (ADS)

    Tobin, Mark; LHCb Upgrade Scintillating Fibre Tracker Group

    2016-07-01

    The LHCb detector will be upgraded during the Long Shutdown 2 (LS2) of the LHC in order to cope with higher instantaneous luminosities and to read out the data at 40 MHz using a trigger-less read-out system. All front-end electronics will be replaced and several sub-detectors must be redesigned to cope with higher occupancy. The current tracking detectors downstream of the LHCb dipole magnet will be replaced by the Scintillating Fibre (SciFi) Tracker. The SciFi Tracker will use scintillating fibres read out by Silicon Photomultipliers (SiPMs). State-of-the-art multi-channel SiPM arrays are being developed to read out the fibres and a custom ASIC will be used to digitise the signals from the SiPMs. The evolution of the design since the Technical Design Report in 2014 and the latest R & D results are presented.

  19. Scintillation and luminescence in transparent colorless single and polycrystalline bulk ceramic ZnS

    SciTech Connect

    McCloy, John S.; Bliss, Mary; Miller, Brian W.; Wang, Zheming; Stave, Sean C.

    2015-01-01

    ZnS:Ag is a well-known extremely bright scintillator used in powder form for α-particle detection and, mixed with powdered LiF, for thermal neutron detection. Recently, we discovered some commercial bulk colorless and transparent, single-crystal and polycrystalline (chemical vapor-deposited) ZnS forms that scintillate in response to α-particles. The scintillation light transmits through the sample thickness (mm), challenging the commonly held assumption that ZnS is opaque to its own scintillation light. Individual α-particle events were imaged in space and time using a charged-particle camera originally developed for medical imaging applications. Photoluminescence (PL) and PL excitation show that scintillating bulk ZnS likely depends on different electronic defects than commercial ZnS powder scintillators. These defects, associated with copper and oxygen, are discussed in relation to PL results and extensive literature assessment. Commercial transparent ZnS is routinely produced by chemical vapor deposition to sizes larger than square meters, enabling potentially novel radiation detection applications requiring large, thick apertures.

  20. Studies on Ca2+-Doped CeBr3 Scintillating Materials

    SciTech Connect

    Guss, P.; Foster, M. E.; Wong, B. M.; Doty, F. P.; Shah, K.; Squillante, M.; Glodo, J.; Yuan, D.

    2013-07-03

    Despite the outstanding scintillation performance characteristics of cerium tribromide (CeBr3) and cerium-activated lanthanum tribromide (LaBr3:Ce), their commercial availability and application is limited due to the difficulties of growing large, crack-free single crystals from these fragile materials. The objective of this investigation was to employ aliovalent doping to increase crystal strength while maintaining the optical properties of the crystal. One divalent dopant (Ca2+) was investigated as a dopant to strengthen CeBr3 without negatively impacting scintillation performance. Ingots containing nominal concentrations of 1.9% of the Ca2+ dopant were grown. Preliminary scintillation measurements are presented for this aliovalently doped scintillator. Ca2+-doped CeBr3 exhibited little or no change in the peak fluorescence emission for 371 nm optical excitation for CeBr3. The structural, electronic, and optical properties of CeBr3 crystals were investigated using the density functional theory within generalized gradient approximation. The calculated lattice parameters are in good agreement with the experimental data. The energy band structures and density of states were obtained. The optical properties of CeBr3, including the dielectric function, were calculated.

  1. Studies on Ca2+-Doped CeBr3 Scintillating Materials

    SciTech Connect

    Guss, P.; Foster, M. E.; Wong, B. M.; Doty, F. P.; Shah, K.; Squillante, M. R.; Shirwadkar, U.; Hawrami, R.; Tower, J.; Yuan, D.

    2013-09-01

    Despite the outstanding scintillation performance characteristics of cerium tribromide (CeBr3) and cerium-activated lanthanum tribromide (LaBr3:Ce), their commercial availability and application is limited due to the difficulties of growing large, crack-free single crystals from these fragile materials. The objective of this investigation was to employ aliovalent doping to increase crystal strength while maintaining the optical properties of the crystal. One divalent dopant (Ca2+) was investigated as a dopant to strengthen CeBr3 without negatively impacting scintillation performance. Ingots containing nominal concentrations of 1.9% of the Ca2+ dopant were grown. Preliminary scintillation measurements are presented for this aliovalently doped scintillator. Ca2+-doped CeBr3 exhibited little or no change in the peak fluorescence emission for 371 nm optical excitation for CeBr3. The structural, electronic, and optical properties of CeBr3 crystals were investigated using the density functional theory within generalized gradient approximation. The calculated lattice parameters are in good agreement with the experimental data. The energy band structures and density of states were obtained. The optical properties of CeBr3, including the dielectric function, were calculated.

  2. Low-energy neutron detector based upon lithium lanthanide borate scintillators

    DOEpatents

    Czirr, John B.

    1998-01-01

    An apparatus for detecting neutrons includes a cerium activated scintillation crystal containing .sup.10 B, with the scintillation crystal emitting light in response to .alpha. particles emitted from the .sup.10 B(n,.alpha.)Li* reaction. The apparatus also includes a gamma scintillator positioned adjacent the crystal and which generates light in response to gamma rays emitted from the decay of Li*. The apparatus further includes a first and a second light-to-electronic signal converter each positioned to respectively receive light from the crystal and the gamma scintillator, and each respectively outputting first and second electronic signals representative of .alpha. particles from the .sup.10 B(n,.alpha.)Li* reaction and gamma rays from the .sup.10 B(n,.alpha.)Li* reaction. The apparatus includes a coincidence circuit connected to receive the first and second signals and which generates a coincidence signal when the first and second signals coincide. The apparatus also includes a data analyzer for receiving an additional signal from at least one of the first and second converters, and for operating in response to the coincidence signal.

  3. Gaseous photomultipliers for the readout of scintillators and detection Cherenkov radiation

    SciTech Connect

    Peskov, V.; Borovik-Romanov, A.

    1993-11-01

    The latest achievements in the development of gaseous detectors for registering UV and visible photons are described. Possible modifications of their design for some particular applications such as the readout of crystal scintillators. noble liquids, fibers and for large area Cherenkov detectors are discussed.

  4. Bridgman bulk growth and scintillation measurements of SrI2:Eu2+

    NASA Astrophysics Data System (ADS)

    Hawrami, R.; Glodo, J.; Shah, K. S.; Cherepy, N.; Payne, S.; Burger, A.; Boatner, L.

    2013-09-01

    Large diameter Bridgman growth of europium activated strontium iodide SrI2:Eu2+ produces crystals with light yield of up to 115,000 ph/MeV with an excellent light yield proportionality. SrI2:Eu2+ exhibits an outstanding energy resolution of better than 3% FWHM at 662 keV. Its emission is centered at 435 nm. The scintillation decays with a 1 μs time constant for small samples and up to 5 μs to larger crystals. This paper presents successful progress made in the vertical Bridgman crystal growth of SrI2:Eu2+ and its scintillator properties. Large diameter, crack-free and transparent SrI2:Eu2+single crystals with diameters of 1 in., 1.3 in., 1.5 in. and 2 in. were all successfully grown.

  5. Detecting scintillations in liquid helium

    NASA Astrophysics Data System (ADS)

    Huffman, P. R.; McKinsey, D. N.

    2013-09-01

    We review our work in developing a tetraphenyl butadiene (TPB)-based detection system for a measurement of the neutron lifetime using magnetically confined ultracold neutrons (UCN). As part of the development of the detection system for this experiment, we studied the scintillation properties of liquid helium itself, characterized the fluorescent efficiencies of different fluors, and built and tested three detector geometries. We provide an overview of the results from these studies as well as references for additional information.

  6. Scintillation Forecasting Using NPOESS Data

    NASA Astrophysics Data System (ADS)

    Basu, B.; Retterer, J.; Demajistre, R.; de La Beaujardiere, O.; Scro, K.

    2005-12-01

    We have conducted a theoretical study of the use of NPOESS data for the forecasting of equatorial radio scintillation using knowledge of the equatorial Appleton anomaly, e.g., the peak-to-valley ratio of TEC (Total Electron Content) between the anomaly crests and the magnetic equator. The peak-to-valley ratio can be obtained from the UV (ultraviolet) imagery of the anomaly region that will be provided by the NPOESS sensors. The post-sunset enhancement of the upward drift velocity of the equatorial plasma has been shown, both theoretically and observationally, to be an important determinant of both the onset of scintillation and the strength of the anomaly. The technical approach is to run PBMOD, the AFRL low-latitude ionosphere model, with a range of post-sunset vertical drift velocities to determine the quantitative relationship between the peak-to-valley ratio and the maximum value of the pot-sunset upward drift velocity of equatorial plasma. Once the relationship is validated, it will be used to estimate the maximum value of the drift velocity from the peak-to-valley ratio, which is derived from the UV imagery data provided by NPOESS-like sensor, such as GUVI on TIMED satellite. The drift velocity will then be used in PBMOD to simulate the formation and evolution of equatorial plasma `bubbles' and calculate the distribution of the amplitude scintillation index S4. Results of the study will be discussed.

  7. Scintillation Reduction Method for Photometric Measurements

    NASA Astrophysics Data System (ADS)

    Ryan, P.; Sandler, D.

    1998-10-01

    We explore the reduction of scintillation via differencing signals from binary stars. Theory has been extended to include temporal and angular separation effects simultaneously. For meter-class telescopes, scintillation for a 2" binary is reduced by greater than a factor of 3. Aperture averaging for differential scintillation had a D^-1.4+/-0.1 dependence for exposure times <=0.25 s versus D^-1.1+/-0.1 for absolute scintillation. For 1.5 m diameter telescopes, the influence of binary separation on differential scintillation for theta<5^'' went as theta^0.6 for instantaneous scintillation and rose slightly with exposure time. If the deconvolution problem can be solved, differencing signals from binary stars offers the potential for increased photometric accuracy.

  8. A Review of Ionospheric Scintillation Models

    NASA Astrophysics Data System (ADS)

    Priyadarshi, S.

    2015-03-01

    This is a general review of the existing climatological models of ionospheric radio scintillation for high and equatorial latitudes. Trans-ionospheric communication of radio waves from transmitter to user is affected by the ionosphere which is highly variable and dynamic in both time and space. Scintillation is the term given to irregular amplitude and phase fluctuations of the received signals and related to the electron density irregularities in the ionosphere. Key sources of ionospheric irregularities are plasma instabilities; every irregularities model is based on the theory of radio wave propagation in random media. It is important to understand scintillation phenomena and the approach of different theories. Therefore, we have briefly discussed the theories that are used to interpret ionospheric scintillation data. The global morphology of ionospheric scintillation is also discussed briefly. The most important (in our opinion) analytical and physical models of scintillation are reviewed here.

  9. A Review of Ionospheric Scintillation Models.

    PubMed

    Priyadarshi, S

    This is a general review of the existing climatological models of ionospheric radio scintillation for high and equatorial latitudes. Trans-ionospheric communication of radio waves from transmitter to user is affected by the ionosphere which is highly variable and dynamic in both time and space. Scintillation is the term given to irregular amplitude and phase fluctuations of the received signals and related to the electron density irregularities in the ionosphere. Key sources of ionospheric irregularities are plasma instabilities; every irregularities model is based on the theory of radio wave propagation in random media. It is important to understand scintillation phenomena and the approach of different theories. Therefore, we have briefly discussed the theories that are used to interpret ionospheric scintillation data. The global morphology of ionospheric scintillation is also discussed briefly. The most important (in our opinion) analytical and physical models of scintillation are reviewed here.

  10. Morphology of auroral zone radio wave scintillation

    SciTech Connect

    Rino, C.L.; Matthews, S.J.

    1980-08-01

    This paper describes the morphology of midnight sector and morning sector auroral zone scintillation observations made over a two-year period using the Wideband satelite, which is in a sun-synchronous, low-altitude orbit. No definitive seasonal variation was found. The nighttime data showed the highest scintillation ocurrence levels, but significant amounts of morning scintillation were observed. For the most part the scintillation activity followed the general pattern of local magnetic activity. The most prominent feature in the nightime data is a localized amplitude and phase scintillation enhancement at the point where the propagation vector lies within an L shell. A geometrical effect due to a dynamic slab of sheetlike structures in the F region is hypothesized as the source of his enhancement. The data have been sorted by magnetic activity, proximity to local midnight, and season. The general features of the data are in agreement with the accepted morphology of auroral zone scintillation.

  11. Neutron response characterization for an EJ299-33 plastic scintillation detector

    DOE PAGES

    Lawrence, Chris C.; Febbraro, Michael; Massey, Thomas N.; ...

    2014-05-10

    Organic scintillation detectors have shown promise as neutron detectors for characterizing special nuclear materials in various arms-control and homeland security applications. Recent advances have yielded a new plastic scintillator - EJ299-33 - with pulse-shape-discrimination (PSD) capability. Plastic scintillators would have a much expanded range of deployment relative to liquids and crystals. Here in this paper, we present a full characterization of pulse height response to fission-energy neutrons for an EJ299-33 detector with 7.62-by-7.62-cm cylindrical active volume, and compare with an EJ309 liquid scintillator in the same assembly. Scintillation light output relations, energy resolutions, and response matrices are presented for bothmore » detectors. A Continuous spectrum neutron source, obtained via the bombardment of 27Al with 7.44-MeV deuterons at the Edwards Accelerator Facility at Ohio University, was used for the measurement. A new procedure for evaluating and comparing PSD performance is presented which accounts for the effect of the light output relation on the ability to detect low energy neutrons. The EJ299-33 is shown to have considerable deficit in matrix condition, and in PSD figure of merit when compared to EJ309, especially when neutron energy is taken into account. Furthermore the EJ299 is likely to bring a modest PSD capability into a array of held applications that are not accessible to liquids or crystals.« less

  12. Neutron response characterization for an EJ299-33 plastic scintillation detector

    SciTech Connect

    Lawrence, Chris C.; Febbraro, Michael; Massey, Thomas N.; Flaska, Marek; Becchetti, F. D.; Pozzi, Sara A.

    2014-05-10

    Organic scintillation detectors have shown promise as neutron detectors for characterizing special nuclear materials in various arms-control and homeland security applications. Recent advances have yielded a new plastic scintillator - EJ299-33 - with pulse-shape-discrimination (PSD) capability. Plastic scintillators would have a much expanded range of deployment relative to liquids and crystals. Here in this paper, we present a full characterization of pulse height response to fission-energy neutrons for an EJ299-33 detector with 7.62-by-7.62-cm cylindrical active volume, and compare with an EJ309 liquid scintillator in the same assembly. Scintillation light output relations, energy resolutions, and response matrices are presented for both detectors. A Continuous spectrum neutron source, obtained via the bombardment of 27Al with 7.44-MeV deuterons at the Edwards Accelerator Facility at Ohio University, was used for the measurement. A new procedure for evaluating and comparing PSD performance is presented which accounts for the effect of the light output relation on the ability to detect low energy neutrons. The EJ299-33 is shown to have considerable deficit in matrix condition, and in PSD figure of merit when compared to EJ309, especially when neutron energy is taken into account. Furthermore the EJ299 is likely to bring a modest PSD capability into a array of held applications that are not accessible to liquids or crystals.

  13. Reflectivity quenching of ESR multilayer polymer film reflector in optically bonded scintillator arrays

    NASA Astrophysics Data System (ADS)

    Loignon-Houle, Francis; Pepin, Catherine M.; Charlebois, Serge A.; Lecomte, Roger

    2017-04-01

    The 3M-ESR multilayer polymer film is a widely used reflector in scintillation detector arrays. As specified in the datasheet and confirmed experimentally by measurements in air, it is highly reflective (> 98 %) over the entire visible spectrum (400-1000 nm) for all angles of incidence. Despite these outstanding characteristics, it was previously found that light crosstalk between pixels in a bonded LYSO scintillator array with ESR reflector can be as high as ∼30-35%. This unexplained light crosstalk motivated further investigation of ESR optical performance. Analytical simulation of a multilayer structure emulating the ESR reflector showed that the film becomes highly transparent to incident light at large angles when surrounded on both sides by materials of refractive index higher than air. Monte Carlo simulations indicate that a considerable fraction (∼25-35%) of scintillation photons are incident at these leaking angles in high aspect ratio LYSO scintillation crystals. The film transparency was investigated experimentally by measuring the scintillation light transmission through the ESR film sandwiched between a scintillation crystal and a photodetector with or without layers of silicone grease. Strong light leakage, up to nearly 30%, was measured through the reflector when coated on both sides with silicone, thus elucidating the major cause of light crosstalk in bonded arrays. The reflector transparency was confirmed experimentally for angles of incidence larger than 60 ° using a custom designed setup allowing illumination of the bonded ESR film at selected grazing angles. The unsuspected ESR film transparency can be beneficial for detector arrays exploiting light sharing schemes, but it is highly detrimental for scintillator arrays designed for individual pixel readout.

  14. Accurate measurement of the rise and decay times of fast scintillators with solid state photon counters

    NASA Astrophysics Data System (ADS)

    Seifert, S.; Steenbergen, J. H. L.; van Dam, H. T.; Schaart, D. R.

    2012-09-01

    In this work we present a measurement setup for the determination of scintillation pulse shapes of fast scintillators. It is based on a time-correlated single photon counting approach that utilizes the correlation between 511 keV annihilation photons to produce start and stop signals in two separate crystals. The measurement is potentially cost-effective and simple to set up while maintaining an excellent system timing resolution of 125 ps. As a proof-of-concept the scintillation photon arrival time histograms were recorded for two well-known, fast scintillators: LYSO:Ce and LaBr3:5%Ce. The scintillation pulse shapes were modeled as a linear combination of exponentially distributed charge transfer and photon emission processes. Correcting for the system timing resolution, the exponential time constants were extracted from the recorded histograms. A decay time of 43 ns and a rise time of 72 ps were determined for LYSO:Ce thus demonstrating the capability of the system to accurately measure very fast rise times. In the case of LaBr3:5%Ce two processes were observed to contribute to the rising edge of the scintillation pulse. The faster component (270 ps) contributes with 72% to the rising edge of the scintillation pulse while the second, slower component (2.0 ns) contributes with 27%. The decay of the LaBr3:5%Ce scintillation pulse was measured to be 15.4 ns with a small contribution (2%) of a component with a larger time constant (130 ns).

  15. Phoswich scintillator for proton and gamma radiation of high energy

    SciTech Connect

    Tengblad, O.; Borge, M. J. G.; Briz, J. A.; Carmona-Gallardo, M.; Cruz, C.; Gugliermina, V.; Nacher, E.; Perea, A.; Sanchez del Rio, J.; Nieves, M. Turrion; Nilsson, T.; Johansson, H. T.; Bergstroem, J.; Blomberg, E.; Buelling, A.; Gallneby, E.; Hagdahl, J.; Jansson, L.; Jareteg, K.; Masgren, R.; and others

    2011-11-30

    We present here a Phoswich scintillator design to achieve both high resolution gamma ray detection, and good efficiency for high energy protons. There are recent developments of new high resolution scintillator materials. Especially the LaBr3(Ce) and LaCl3(Ce) crystals have very good energy resolution in the order of 3% for 662 keV gamma radiation. In addition, these materials exhibit a very good light output (63 and 32 photons/keV respectively).A demonstrator detector in the form of an Al cylinder of 24 mm diameter and a total length of 80 mm with 2 mm wall thickness, containing a LaBr3(Ce) crystal of 20 mm diameter and 30 mm length directly coupled to a LaCl3(Ce) crystal of 50 mm length, and closed with a glass window of 5 mm, was delivered by Saint Gobain. To the glass window a Hamamatsu R5380 Photomultiplier tube (PMT) was coupled using silicon optical grease.

  16. Scintillator tiles read out with silicon photomultipliers

    NASA Astrophysics Data System (ADS)

    Pooth, O.; Radermacher, T.; Weingarten, S.; Weinstock, L.

    2015-10-01

    A detector prototype based on a fast plastic scintillator read out with silicon photomultipliers is presented. All studies have been done with cosmic muons and focus on parameter optimization such as coupling the SiPM to the scintillator or wrapping the scintillator with reflective material. The prototype shows excellent results regarding the light-yield and offers a detection efficiency of 99.5% with a signal purity of 99.9% for cosmic muons.

  17. Holes: Ionospheric Scintillation, GPS and Imputation

    DTIC Science & Technology

    2007-03-01

    HOLES: IONOSPHERIC SCINTILLATION GPS AND IMPUTATION THESIS Robert A. Steenburgh, Senior Master Sergeant, USAF AFIT/GAP/ENP/07-06 DEPARTMENT OF THE...of Defense, or the United States Government. AFIT/GAP/ENP/07-06 HOLES: IONOSPHERIC SCINTILLATION GPS AND IMPUTATION THESIS Presented to the Faculty...Master Sergeant, USAF March 2007 APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED. AFIT/GAP/ENP/07-06 HOLES: IONOSPHERIC SCINTILLATION GPS AND

  18. Neutron position-sensitive scintillation detector

    DOEpatents

    Strauss, Michael G.; Brenner, Raul

    1984-01-01

    A device is provided for mapping one- and two-dimensional distributions of neutron-positions in a scintillation detector. The device consists of a lithium glass scintillator coupled by an air gap and a light coupler to an array of photomultipliers. The air gap concentrates light flashes from the scintillator, whereas the light coupler disperses this concentrated light to a predetermined fraction of the photomultiplier tube array.

  19. Low-cost extruded plastic scintillator

    NASA Astrophysics Data System (ADS)

    Pla-Dalmau, Anna; Bross, Alan D.; Mellott, Kerry L.

    2001-07-01

    Motivated by a need for lower cost plastic scintillation detectors, we have tested commercially available polystyrene pellets in order to produce scintillating materials that can be extruded into various shapes. Selection of the raw materials is discussed. Two techniques are described that add wavelength shifting dopants to polystyrene pellets and extrude plastic scintillating bars using these materials. Data on light yield and transmittance are presented.

  20. Recording of relativistic particles in thin scintillators

    SciTech Connect

    Tolstukhin, I A.; Somov, Alexander S.; Somov, S. V.; Bolozdynya, A. I.

    2014-11-01

    Results of investigating an assembly of thin scintillators and silicon photomultipliers for registering relativistic particles with the minimum ionization are presented. A high efficiency of registering relativistic particles using an Ej-212 plastic scintillator, BSF-91A wavelength-shifting fiber (Saint-Gobain), and a silicon photomultiplier (Hamamtsu) is shown. The measurement results are used for creating a scintillation hodoscope of the magnetic spectrometer for registering γ quanta in the GlueX experiment.

  1. Spacecraft Radio Scintillation and Solar System Exploration

    NASA Technical Reports Server (NTRS)

    Woo, Richard

    1993-01-01

    When a wave propagates through a turbulent medium, scattering by the random refractive index inhomogeneities can lead to a wide variety of phenomena that have been the subject of extensive study. The observed scattering effects include amplitude or intensity scintillation, phase scintillation, angular broadening, and spectral broadening, among others. In this paper, I will refer to these scattering effects collectively as scintillation. Although the most familiar example is probably the twinkling of stars (light wave intensity scintillation by turbulence in the Earth's atmosphere), scintillation has been encountered and investigated in such diverse fields as ionospheric physics, oceanography, radio astronomy, and radio and optical communications. Ever since planetary spacecraft began exploring the solar system, scintillation has appeared during the propagation of spacecraft radio signals through planetary atmospheres, planetary ionospheres, and the solar wind. Early studies of these phenomena were motivated by the potential adverse effects on communications and navigation, and on experiments that use the radio link to conduct scientific investigations. Examples of the latter are radio occultation measurements (described below) of planetary atmospheres to deduce temperature profiles, and the search for gravitational waves. However,these concerns soon gave way to the emergence of spacecraft radio scintillation as a new scientific tool for exploring small-scale dynamics in planetary atmospheres and structure in the solar wind, complementing in situ and other remote sensing spacecraft measurements, as well as scintillation measurements using natural (celestial) radio sources. The purpose of this paper is to briefly describe and review the solar system spacecraft radio scintillation observations, to summarize the salient features of wave propagation analyses employed in interpreting them, to underscore the unique remote sensing capabilities and scientific relevance of

  2. Scintillation properties of pure CaF 2

    NASA Astrophysics Data System (ADS)

    Mikhailik, V. B.; Kraus, H.; Imber, J.; Wahl, D.

    2006-10-01

    The temperature dependence of the decay time and scintillation light yield of pure CaF 2 crystal was measured over the temperature range 8-305 K using the multiphoton coincidence counting technique. Pure CaF 2 exhibits emission of triplet self-trapped excitons at 280 nm with a slow decay, the time constant of which changes significantly with temperature. The main decay time constant increases by three orders of magnitude when cooled, from 0.96±0.06 μs at 295 K to 930±40 μs at 8 K. The results obtained demonstrate that the scintillation light yield of pure CaF 2 increases with decreasing temperature down to 20 K below which it is roughly constant. At low temperatures the light yield of CaF 2 is estimated to be 60% relative to that of pure CaWO 4. It is concluded that undoped calcium fluoride is a very attractive target material for experimental searches for rare events based on the detection of phonon and scintillation signals.

  3. Scintillation characteristics of nonstoichiometric phases formed in MF 2-GdF 3-CeF 3 systems Part III. Dense Gd 1- x- yM xCe yF 3- x tysonite-related crystals (M=Ca, Sr)

    NASA Astrophysics Data System (ADS)

    Kobayashi, M.; Ishii, M.; Sobolev, B. P.; Zhmurova, Z. I.; Krivandina, E. A.; Nikl, M.

    1999-01-01

    We evaluated the scintillation characteristics and the radiation hardness of Gd 1- xCa xF 3- x and Gd 1- xSr xF 3- x tysonite-type solid solutions (close to 6.6 g/cm 3 in density) doped with Ce which were grown from the congruent melt. As the Ce concentration increased, the Ce 3+ emission at 345 nm increased to a level comparable with the Gd 3+ emission at 310 nm. Both emissions, however, were slow with the decay constant in the order of ms. The radiation hardness, which was roughly 10 4 rad, tends to degrade as the wavelength decreases and/or the Ce concentration increases. Both spontaneous recovery and UV annealing of the radiation damages were significant. The intensity of the γ-ray excited luminescence, integrated over time, was as large as 50% of that in BaF 2 (12% of that in CdWO 4). When the Ce concentration is nil or only small, the yellow-green luminescence for UV excitation was as intense as in CdWO 4. Although the present crystals are not good for the applications in high-energy physics experiments, they may find applications in display devices, thermal neutron monitors, etc.

  4. A multi-channel setup to study fractures in scintillators

    NASA Astrophysics Data System (ADS)

    Tantot, A.; Bouard, C.; Briche, R.; Lefèvre, G.; Manier, B.; Zaïm, N.; Deschanel, S.; Vanel, L.; Di Stefano, P. C. F.

    2016-12-01

    To investigate fractoluminescence in scintillating crystals used for particle detection, we have developed a multi-channel setup built around samples of double-cleavage drilled compression (DCDC) geometry in a controllable atmosphere. The setup allows the continuous digitization over hours of various parameters, including the applied load, and the compressive strain of the sample, as well as the acoustic emission. Emitted visible light is recorded with nanosecond resolution, and crack propagation is monitored using infrared lighting and camera. An example of application to \\text{B}{{\\text{i}}4}\\text{G}{{\\text{e}}3}{{\\text{O}}12} (BGO) is provided.

  5. High-symmetry organic scintillator systems

    DOEpatents

    Feng, Patrick L.

    2017-06-14

    An ionizing radiation detector or scintillator system includes a scintillating material comprising an organic crystalline compound selected to generate photons in response to the passage of ionizing radiation. The organic compound has a crystalline symmetry of higher order than monoclinic, for example an orthorhombic, trigonal, tetragonal, hexagonal, or cubic symmetry. A photodetector is optically coupled to the scintillating material, and configured to generate electronic signals having pulse shapes based on the photons generated in the scintillating material. A discriminator is coupled to the photon detector, and configured to discriminate between neutrons and gamma rays in the ionizing radiation based on the pulse shapes of the output signals.

  6. Radio wave scintillations at equatorial regions

    NASA Technical Reports Server (NTRS)

    Poularikas, A. D.

    1972-01-01

    Radio waves, passing through the atmosphere, experience amplitude and phase fluctuations know as scintillations. A characterization of equatorial scintillation, which has resulted from studies of data recorded primarily in South America and equatorial Africa, is presented. Equatorial scintillation phenomena are complex because they appear to vary with time of day (pre-and postmidnight), season (equinoxes), and magnetic activity. A wider and more systematic geographical coverage is needed for both scientific and engineering purposes; therefore, it is recommended that more observations should be made at earth stations (at low-geomagnetic latitudes) to record equatorial scintillation phenomena.

  7. High-symmetry organic scintillator systems

    DOEpatents

    Feng, Patrick L.

    2017-09-05

    An ionizing radiation detector or scintillator system includes a scintillating material comprising an organic crystalline compound selected to generate photons in response to the passage of ionizing radiation. The organic compound has a crystalline symmetry of higher order than monoclinic, for example an orthorhombic, trigonal, tetragonal, hexagonal, or cubic symmetry. A photodetector is optically coupled to the scintillating material, and configured to generate electronic signals having pulse shapes based on the photons generated in the scintillating material. A discriminator is coupled to the photon detector, and configured to discriminate between neutrons and gamma rays in the ionizing radiation based on the pulse shapes of the output signals.

  8. High-symmetry organic scintillator systems

    DOEpatents

    Feng, Patrick L.

    2017-07-18

    An ionizing radiation detector or scintillator system includes a scintillating material comprising an organic crystalline compound selected to generate photons in response to the passage of ionizing radiation. The organic compound has a crystalline symmetry of higher order than monoclinic, for example an orthorhombic, trigonal, tetragonal, hexagonal, or cubic symmetry. A photodetector is optically coupled to the scintillating material, and configured to generate electronic signals having pulse shapes based on the photons generated in the scintillating material. A discriminator is coupled to the photon detector, and configured to discriminate between neutrons and gamma rays in the ionizing radiation based on the pulse shapes of the output signals.

  9. Waveshifters and Scintillators for Ionizing Radiation Detection

    SciTech Connect

    B.Baumgaugh; J.Bishop; D.Karmgard; J.Marchant; M.McKenna; R.Ruchti; M.Vigneault; L.Hernandez; C.Hurlbut

    2007-12-11

    Scintillation and waveshifter materials have been developed for the detection of ionizing radiation in an STTR program between Ludlum Measurements, Inc. and the University of Notre Dame. Several new waveshifter materials have been developed which are comparable in efficiency and faster in fluorescence decay than the standard material Y11 (K27) used in particle physics for several decades. Additionally, new scintillation materials useful for fiber tracking have been developed which have been compared to 3HF. Lastly, work was done on developing liquid scintillators and paint-on scintillators and waveshifters for high radiation environments.

  10. Performance of wavefront sensors in strong scintillation

    NASA Astrophysics Data System (ADS)

    Barchers, Jeffrey D.; Fried, David L.; Link, Donald J.; Tyler, Glenn A.; Moretti, William; Brennan, Terry J.; Fugate, Robert Q.

    2003-02-01

    The estimation accuracy of wavefront sensors in strong scintillation is examined. Wave optical simulation is used to characterize the performance of several wavefront sensors in the absence of measurement noise. The estimation accuracy of a Schack-Hartmann sensor is shown to be poor in strong scintillation due primarily to the presence of branch points in the phase function. The estimation accuracy of a unit-shear, shearing interferometer is found to be significantly better than that of a Hartmann sensor in strong scintillation. The estimation accuracy of a phase shifting point diffraction interferometer is shown to be invariant with scintillation.

  11. Solid scintillation counting: a new technique for measuring radiolabeled compounds.

    PubMed

    Wunderly, S W

    1989-01-01

    This report describes the theory and practice of anew solid scintillator technique for measurement of radiolabeled compounds useful in bioresearch. Solid scintillation counting is expected to replace liquid scintillation counting in certain applications involving non-volatile radiolabeled substrates.

  12. PREFACE: Applications of Novel Scintillators for Research and Industry (ANSRI 2015)

    NASA Astrophysics Data System (ADS)

    Roberts, O. J.

    2015-06-01

    Scintillator detectors are used widely in the field of γ- and X-ray spectroscopy, particularly in the mid 1900s when the invention of NaI(Tl) by nobel laureate Robert Hofstadter in 1948, spurred the creation of new scintillator materials. In the development of such new scintillators, important characteristics such as its intrinsic efficiency, position sensitivity, robustness, energy and timing response, light output, etc, need to be addressed. To date, these requirements cannot be met by a single type of scintillator alone and therefore the development of an ''ideal'' scintillator remains the holy grail of nuclear instrumentation. Consequently, the last two decades have seen significant progress in the development of scintillator crystals, driven largely by technological advances. Conventional inorganic scintillators such as NaI(Tl) and BGO are now being replaced with better, novel organic, inorganic, ceramic and plastic scintillators offering a wider variety of options for many applications. The workshop on the Applications of Novel Scintillators in Research and Industry was held at University College Dublin in January 2015 and covered a wide range of topics that characterise modern advances in the field of scintillator technology. This set of proceedings covers areas including the growth, production and characterisation of such contemporary scintillators, along with their applications in various fields, such as; Medical Imaging; Defence/Security; Astrophysics; and Nuclear/Particle Physics. We would like to thank all those who presented their recent results on their research at the workshop. These proceedings atest to the excitement and interest in such a broad field, that pervades the pursuit of the development of novel materials for future applications. We would also like to thank Professor Luigi Piro, for giving an interesting public talk during the conference, and to the Institute of Physics Ireland Group for supporting the event. We thank ORTEC for

  13. {Y 3- x,Yb x}[Ga] 2(Ga) 3O 12 and {Lu 2Yb 1}[Al] 2(Al) 3O 12 single crystals for scintillator application grown by the modified micro-pulling-down method

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Akira; Akagi, Tadahiro; Nikl, Martin; Solovieva, Natalia; Lebbou, Kheirreddine; Dujardin, Christophe; Pédrini, Christian; Fukuda, Tsuguo

    2002-06-01

    In order to investigate proper hosts for charge transitions (CT) of Yb 3+, the gallium garnet host (YGG) and aluminium garnet host (LuAG) were studied. Transparent and crack-free heavily Yb-doped YGG, i.e. {Y 3- x,Yb x}[Ga] 2(Ga) 3O 12, x=0.15, 0.5, 1.0 and heavily Yb-doped LuAG, i.e. {Lu 2Yb 1}[Al] 2(Al) 3O 12 single crystals were grown by the modified pulling-down method with <1 1 1> orientation. Emission, excitation spectra and decay kinetics were measured for these crystals. The CT of Yb 3+ in the YGG host were discussed compared with the Yb 3+ one in the LuAG host.

  14. Microstructure, optical, and scintillation characteristics of Pr3+ doped Lu3Al5O12 optical ceramics

    NASA Astrophysics Data System (ADS)

    Shi, Yun; Nikl, Martin; Feng, Xiqi; Mares, Jiri A.; Shen, Yiqiang; Beitlerova, A.; Kucerkova, R.; Pan, Yubai; Liu, Qian

    2011-01-01

    0.5, 1.0, and 5.0 at. % Pr3+ doped Lu3Al5O12 (Pr:LuAG) optical ceramics are fabricated and compared with Bi4Ge3O12 (BGO) and Pr:LuAG single crystals as for their optical, luminescence and scintillation properties. Radio-luminescence intensity of the fast UV emission based on 5d1→4f Pr3+ transition reaches up to 20 times of that of BGO single crystal reference scintillator. Photoelectron yield of the best performing 0.5 at. % Pr:LuAG ceramic sample is about 1002 phels/MeV, about 30% lower than that of BGO reference sample and about 65% lower than that of Pr:LuAG single crystal. The trapping phenomena at grain boundaries and/or structural defects are proposed as the main cause of degradation of the scintillation response of the Pr:LuAG optical ceramics.

  15. Comparison of the imaging performances for recently developed monolithic scintillators: CRY018 and CRY019 for dual isotope gamma ray imaging applications

    NASA Astrophysics Data System (ADS)

    Polito, C.; Pani, R.; Trigila, C.; Cinti, M. N.; Fabbri, A.; Frantellizzi, V.; De Vincentis, G.; Pellegrini, R.; Pani, R.

    2017-01-01

    The growing interest for new scintillation crystals with outstanding imaging performances (i.e. resolution and efficiency) has suggested the study of recently discovered scintillators named CRY018 and CRY019. The crystals under investigation are monolithic and have shown enhanced characteristics both for gamma ray spectrometry and for Nuclear Medicine imaging applications such as the dual isotope imaging. Moreover, the non-hygroscopic nature and the absence of afterglow make these scintillators even more attractive for the potential improvement in a wide range of applications. These scintillation crystals show a high energy resolution in the energy range involved in Nuclear Medicine, allowing the discrimination between very close energy values. Moreover, in order to prove their suitability of being powerful imaging systems, the imaging performances like the position linearity and the intrinsic spatial resolution have been evaluated obtaining satisfactory results thanks to the implementation of an optimized algorithm for the images reconstruction.

  16. Ruby-based inorganic scintillation detectors for 192Ir brachytherapy

    NASA Astrophysics Data System (ADS)

    Kertzscher, Gustavo; Beddar, Sam

    2016-11-01

    We tested the potential of ruby inorganic scintillation detectors (ISDs) for use in brachytherapy and investigated various unwanted luminescence properties that may compromise their accuracy. The ISDs were composed of a ruby crystal coupled to a poly(methyl methacrylate) fiber-optic cable and a charge-coupled device camera. The ISD also included a long-pass filter that was sandwiched between the ruby crystal and the fiber-optic cable. The long-pass filter prevented the Cerenkov and fluorescence background light (stem signal) induced in the fiber-optic cable from striking the ruby crystal, which generates unwanted photoluminescence rather than the desired radioluminescence. The relative contributions of the radioluminescence signal and the stem signal were quantified by exposing the ruby detectors to a high-dose-rate brachytherapy source. The photoluminescence signal was quantified by irradiating the fiber-optic cable with the detector volume shielded. Other experiments addressed time-dependent luminescence properties and compared the ISDs to commonly used organic scintillator detectors (BCF-12, BCF-60). When the brachytherapy source dwelled 0.5 cm away from the fiber-optic cable, the unwanted photoluminescence was reduced from  >5% to  <1% of the total signal as long as the ISD incorporated the long-pass filter. The stem signal was suppressed with a band-pass filter and was  <3% as long as the source distance from the scintillator was  <7 cm. Some ruby crystals exhibited time-dependent luminescence properties that altered the ruby signal by  >5% within 10 s from the onset of irradiation and after the source had retracted. The ruby-based ISDs generated signals of up to 20 times that of BCF-12-based detectors. The study presents solutions to unwanted luminescence properties of ruby-based ISDs for high-dose-rate brachytherapy. An optic filter should be sandwiched between the ruby crystal and the fiber-optic cable to suppress the

  17. Ruby-based inorganic scintillation detectors for (192)Ir brachytherapy.

    PubMed

    Kertzscher, Gustavo; Beddar, Sam

    2016-11-07

    We tested the potential of ruby inorganic scintillation detectors (ISDs) for use in brachytherapy and investigated various unwanted luminescence properties that may compromise their accuracy. The ISDs were composed of a ruby crystal coupled to a poly(methyl methacrylate) fiber-optic cable and a charge-coupled device camera. The ISD also included a long-pass filter that was sandwiched between the ruby crystal and the fiber-optic cable. The long-pass filter prevented the Cerenkov and fluorescence background light (stem signal) induced in the fiber-optic cable from striking the ruby crystal, which generates unwanted photoluminescence rather than the desired radioluminescence. The relative contributions of the radioluminescence signal and the stem signal were quantified by exposing the ruby detectors to a high-dose-rate brachytherapy source. The photoluminescence signal was quantified by irradiating the fiber-optic cable with the detector volume shielded. Other experiments addressed time-dependent luminescence properties and compared the ISDs to commonly used organic scintillator detectors (BCF-12, BCF-60). When the brachytherapy source dwelled 0.5 cm away from the fiber-optic cable, the unwanted photoluminescence was reduced from  >5% to  <1% of the total signal as long as the ISD incorporated the long-pass filter. The stem signal was suppressed with a band-pass filter and was  <3% as long as the source distance from the scintillator was  <7 cm. Some ruby crystals exhibited time-dependent luminescence properties that altered the ruby signal by  >5% within 10 s from the onset of irradiation and after the source had retracted. The ruby-based ISDs generated signals of up to 20 times that of BCF-12-based detectors. The study presents solutions to unwanted luminescence properties of ruby-based ISDs for high-dose-rate brachytherapy. An optic filter should be sandwiched between the ruby crystal and the fiber-optic cable to suppress the

  18. X-ray luminescence based spectrometer for investigation of scintillation properties

    SciTech Connect

    Varney, C. R.; Khamehchi, M. A.; Ji, Jianfeng; Selim, F. A.

    2012-10-15

    A new x-ray luminescence based spectrometer was developed and installed to examine the scintillation properties of materials while revealing the origins of luminescence and investigating trapping defects. Measurements were performed on a number of undoped and Ce doped yttrium aluminum garnet crystals and various luminescence centers were characterized. The measured x-ray luminescence spectra provide information about the spectral range and the scintillation efficiency and linearity. The efficiency of charge-carriers production due to x ray, their energy transfer to the luminescence centers, and the efficiency of luminescence are all reflected in the efficiency of x-ray luminescence.

  19. Tl2LaCl5:Ce, high performance scintillator for gamma-ray detectors

    NASA Astrophysics Data System (ADS)

    Hawrami, R.; Ariesanti, E.; Wei, H.; Finkelstein, J.; Glodo, J.; Shah, K. S.

    2017-10-01

    This paper reports on a new Ce-doped Tl-based scintillator, Tl2LaCl5 (TLC), for gamma-ray detection. 10 mm diameter crystals have been successfully grown using the vertical Bridgman method. The emission peak of TLC is detected at 383 nm under X-ray excitation. The light yield of TLC is 76,000 ph/MeV. The samples show excellent energy resolution of 3.4% (FWHM) at 662 keV. The non-proportionality is less than 1%, from 32 keV to 1275 keV. The major scintillation decay time is 36 ns.

  20. Testing a new NIF neutron time-of-flight detector with a bibenzyl scintillator on OMEGA.

    PubMed

    Glebov, V Yu; Forrest, C; Knauer, J P; Pruyne, A; Romanofsky, M; Sangster, T C; Shoup, M J; Stoeckl, C; Caggiano, J A; Carman, M L; Clancy, T J; Hatarik, R; McNaney, J; Zaitseva, N P

    2012-10-01

    A new neutron time-of-flight (nTOF) detector with a bibenzyl crystal as a scintillator has been designed and manufactured for the National Ignition Facility (NIF). This detector will replace a nTOF20-Spec detector with an oxygenated xylene scintillator currently operational on the NIF to improve the areal-density measurements. In addition to areal density, the bibenzyl detector will measure the D-D and D-T neutron yield and the ion temperature of indirect- and direct-drive-implosion experiments. The design of the bibenzyl detector and results of tests on the OMEGA Laser System are presented.

  1. Scintillation properties of Pr-activated LuAlO 3

    NASA Astrophysics Data System (ADS)

    Drozdowski, Winicjusz; Wojtowicz, Andrzej J.; Wiśniewski, Dariusz; Łukasiewicz, Tadeusz; Kisielewski, Jarosław

    2006-01-01

    Praseodymium activated LuAlO 3 (LuAP) crystals have been grown using the Czochralski method at ITME, Warsaw. In this communication the measurements of radioluminescence (RL), low temperature thermoluminescence (TL), room temperature afterglow (AG), scintillation light yields (LY), and scintillation time profiles (STP), performed on polished 2 × 2 × 10 mm pixels with three Pr concentrations (0.003, 0.04, and 0.08 at.%), are reported. Two sets of samples are compared: (i) "as grown", and (ii) annealed in H 2 atmosphere.

  2. Photodetectors for Scintillator Proportionality Measurement

    SciTech Connect

    Moses, William W.; Choong, Woon-Seng; Hull, Giulia; Payne, Steve; Cherepy, Nerine; Valentine, J.D.

    2010-10-18

    We evaluate photodetectors for use in a Compton Coincidence apparatus designed for measuring scintillator proportionality. There are many requirements placed on the photodetector in these systems, including active area, linearity, and the ability to accurately measure low light levels (which implies high quantum efficiency and high signal-to-noise ratio). Through a combination of measurement and Monte Carlo simulation, we evaluate a number of potential photodetectors, especially photomultiplier tubes and hybrid photodetectors. Of these, we find that the most promising devices available are photomultiplier tubes with high ({approx}50%) quantum efficiency, although hybrid photodetectors with high quantum efficiency would be preferable.

  3. Epoxy resins produce improved plastic scintillators

    NASA Technical Reports Server (NTRS)

    Markley, F. W.

    1967-01-01

    Plastic scintillator produced by the substitution of epoxy resins for the commonly used polystyrene is easy to cast, stable at room temperature, and has the desirable properties of a thermoset or cross-linked system. Such scintillators can be immersed directly in strong solvents, an advantage in many chemical and biological experiments.

  4. Scintillator handbook with emphasis on cesium iodide

    NASA Technical Reports Server (NTRS)

    Tidd, J. L.; Dabbs, J. R.; Levine, N.

    1973-01-01

    This report provides a background of reasonable depth and reference material on scintillators in general. Particular attention is paid to the cesium iodide scintillators as used in the High Energy Astronomy Observatory (HEAO) experiments. It is intended especially for use by persons such as laboratory test personnel who need to obtain a working knowledge of these materials and their characteristics in a short time.

  5. Binderless composite scintillator for neutron detection

    DOEpatents

    Hodges, Jason P [Knoxville, TN; Crow, Jr; Lowell, M [Oak Ridge, TN; Cooper, Ronald G [Oak Ridge, TN

    2009-03-10

    Composite scintillator material consisting of a binderless sintered mixture of a Lithium (Li) compound containing .sup.6Li as the neutron converter and Y.sub.2SiO.sub.5:Ce as the scintillation phosphor, and the use of this material as a method for neutron detection. Other embodiments of the invention include various other Li compounds.

  6. The Temporal Structure of Strongly Scintillating Signals.

    DTIC Science & Technology

    1979-01-31

    referred to as "equatorial spread-F." The discovery of gigahertz scintillation (Craft and Westerlund , 1972) was II unexpected, although nighttime...and L. H. Westerlund , "Scintillations at 4 and 6 GHz Caused by the Ionosphere," paper presented at AIAA 10th Aerospace Sciences Meeting, San Diego

  7. Current status on plastic scintillators modifications

    SciTech Connect

    Hamel, Matthieu; Bertrand, Guillaume H.V.; Carrel, Frederick; Coulon, Romain; Dumazert, Jonathan; Montbarbon, Eva; Sguerra, Fabien

    2015-07-01

    Recent developments of plastic scintillators are reviewed, from 2000 to March 2015. All examples are distributed into the main purpose, i.e. the nature of the radionuclide provided with the scope of detection of various radiation particles. The main characteristics of these newly created scintillators and their detection properties are given. (authors)

  8. A scintillation playback system for quantum links

    NASA Astrophysics Data System (ADS)

    Rabinovich, William S.; Mahon, Rita; Bashkansky, Mark; Freeman, Rachel; Reintjes, John

    2017-02-01

    Quantum key distribution (QKD) using free space optical (FSO) systems will, in most applications, involve atmospheric propagation. As is well known from classical FSO communication links, turbulence can cause large power variation in the link strength. Optical scintillation can cause fades below and surges above the mean power that last tens of milliseconds. Fades can be as deep as 20-30 dB. Previously we have demonstrated a system that allows laboratory studies of the effects of scintillation that faithfully represent the effects seen in the field. Scintillation is recorded using a modified FSO system and then played back in the laboratory using a fiber optic based system. The result is a laboratory experiment that reproduces, with high fidelity, the field conditions and component performance of the actual link. We have applied this same technique to studying scintillation effects on a QKD link. Scintillation was recorded at the US Naval Research Laboratory's Maritime Lasercom Testbed This facility has sites on both sides of Chesapeake Bay separated by 16 km. A single-photon scintillation playback system was constructed. This scintillation playback system was designed to implement a BB84 protocol, but other QKD protocols could also be used. After the playback experiment the data can be analyzed to determine key length, error rate and other parameters. The set up can be used to study a variety of protocols for QKD in scintillation. Application to studies such as this will be presented.

  9. Atmospheric Neutron Measurements using a Small Scintillator Based Detector

    NASA Astrophysics Data System (ADS)

    Kole, Merlin; Pearce, Mark; Fukazawa, Yasushi; Fukuda, Kentaro; Ishizu, Sumito; Jackson, Miranda; Kamae, Tune; Kawaguchi, Noriaki; Kawano, Takafumi; Kiss, Mozsi; Moretti, Elena; Yanagida, Takayuki; Chauvin, Maxime; Mikhalev, Victor; Rydstrom, Stefan; Takahashi, Hiromitsu

    PoGOLino is a standalone scintillator-based neutron detector designed for balloon-borne missions. Its main purpose is to provide data of the neutron flux in 2 different energy ranges in the high altitude / high latitude region where the highest neutron flux in the atmosphere is found. Furthermore the influence of the Solar activity upon the neutron environment in this region is relatively strong. As a result both short and long term time fluctuations are strongest in this region. At high altitudes neutrons can form a source of background for balloon-borne scientific measurements. They can furthermore form a major source for single event upsets in electronics. A good understanding of the high altitude / high latitude neutron environment is therefore important. Measurements of the neutron environment in this region are however lacking. PoGOLino contains two 5 mm thick Lithium Calcium Aluminium Fluoride (LiCAF) scintillators used for neutron detection. The LiCAF crystals are sandwiched between 2 Bismuth Germanium Oxide (BGO) scintillating crystals, which serve to veto signals produced by gamma-rays and charged particles. The veto system makes measurements of the neutron flux possible even in high radiation environments. One LiCAF detector is shielded with polyethylene while the second remains unshielded, making the detectors sensitive in different energy ranges. The choice of a scintillator crystals as the detection material ensures a high detection efficiency while keeping the instrument small, robust and light weight. The full standalone cylindrical instrument has a radius of 120 mm, a height of 670 mm and a total mass of 13 kg, making it suitable as a piggy back mission. PoGOLino was successfully launched on March 20th 2013 from the Esrange Space Center in Northern Sweden to an altitude of 30.9 km. A detailed description of the detector design is presented, along with results of of the flight. The neutron flux measured during flight is compared to predictions based

  10. Radio wave scintillations in the ionosphere

    NASA Astrophysics Data System (ADS)

    Yeh, K. C.; Liu, C.-H.

    1982-04-01

    A review is provided of the current status of the ionosphere scintillation of radio waves, taking into account both observational and theoretical points of view. Particular attention is given to aspects of transionospheric radio wave propagation and signal statistics. The characterization of ionospheric irregularities is discussed. The observational evidence is considered along with correlation functions and spectra, the optical path and the correlation of the total electron content, the optical path structure function, and frozen fields and their generalizations. Scintillation theories are examined, taking into account a statement of the problem, the phase screen theory, a theory for weak scintillation, the parabolic equation method, the probability distributions of the scintillating signals, and polarization scintillation. A description is provided of experimental results, and aspects of temporal behavior are investigated.

  11. Empirical modelling of equatorial ionospheric scintillation

    NASA Astrophysics Data System (ADS)

    Pasricha, P. K.; Reddy, B. M.

    1986-06-01

    A computer-based model of ionospheric scintillations has been developed by Fremouw (socalled the WBMOD model) to give a mean scintillation index for a given set of observing conditions. The WBMOD model incorporates some of the scintillation observations made with the DNA wideband satellite. A comparison is made between the scintillation morphology observed at an equatorial station Ooty with the one evolved with the WBMOD model. Morphological features at other stations in the equatorial region are briefly described. The WBMOD model predicts the pre-midnight maximum seen at the Indian longitudes. The seasonal pattern reproduced by the model incorporates longitudinal variability. The solar activity dependence in the model seems to be rather high. Empirical expressions giving the dependence of scintillation index on morphological parameters are obtained

  12. Extruded scintillator for the Calorimetry applications

    NASA Astrophysics Data System (ADS)

    Dyshkant, A.; Rykalin, V.; Pla-Dalmau, A.; Beznosko, D.

    2006-10-01

    An extrusion line has been installed and successfully operated at FNAL (Fermi National Accelerator Laboratory) in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new Facility will serve to further develop and improve extruded plastic scintillator. Recently progress has been made in producing co-extruded plastic scintillator, thus increasing the potential HEP applications of this Facility. The current R&D work with extruded and co-extruded plastic scintillator for a potential ALICE upgrade, the ILC calorimetry program and the MINERvA experiment show the attractiveness of the chosen strategy for future experiments and calorimetry. We extensively discuss extruded and co-extruded plastic scintillator in calorimetry in synergy with new Solid State Photomultipliers. The characteristics of extruded and co-extruded plastic scintillator will be presented here as well as results with non-traditional photo read-out.

  13. Extruded scintillator for the calorimetry applications

    SciTech Connect

    Dyshkant, A.; Rykalin, V.; Pla-Dalmau, A.; Beznosko, D.; /SUNY, Stony Brook

    2006-08-01

    An extrusion line has been installed and successfully operated at FNAL (Fermi National Accelerator Laboratory) in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new Facility will serve to further develop and improve extruded plastic scintillator. Recently progress has been made in producing co-extruded plastic scintillator, thus increasing the potential HEP applications of this Facility. The current R&D work with extruded and co-extruded plastic scintillator for a potential ALICE upgrade, the ILC calorimetry program and the MINERvA experiment show the attractiveness of the chosen strategy for future experiments and calorimetry. We extensively discuss extruded and co-extruded plastic scintillator in calorimetry in synergy with new Solid State Photomultipliers. The characteristics of extruded and co-extruded plastic scintillator will be presented here as well as results with non-traditional photo read-out.

  14. Temperature dependence of CsI(Tl) gamma-ray excited scintillation characteristics

    SciTech Connect

    Not Available

    1993-10-01

    Gamma-ray excited emission spectrum, absolute scintillation yield, rise and decay time constants, and thermoluminescence emissions of CsI(Tl) were measured at {minus}100 to +50 C, for crystals from 4 different vendors. The thermoluminescence glow curves were the only property that varied significantly from crystal to crystal; room temperature operation in current mode could be susceptible to temperature fluctuations. The CsI(Tl) emission spectrum has emission bands peaking around 400 and 560 nm; the former band disappears between {minus}50 and {minus}75 C. The RT absolute scintillation yield was calculated to be 65,500{plus_minus}4,100 photons/MeV. The two primary decay time constants increases about exponentially with inverse temperature. An ultra-fast decay component was confirmed. Applications are discussed.

  15. Scintillation Effects on Space Shuttle GPS Data

    NASA Technical Reports Server (NTRS)

    Goodman, John L.; Kramer, Leonard

    2001-01-01

    Irregularities in ionospheric electron density result in variation in amplitude and phase of Global Positioning System (GPS) signals, or scintillation. GPS receivers tracking scintillated signals may lose carrier phase or frequency lock in the case of phase sc intillation. Amplitude scintillation can cause "enhancement" or "fading" of GPS signals and result in loss of lock. Scintillation can occur over the equatorial and polar regions and is a function of location, time of day, season, and solar and geomagnetic activity. Mid latitude regions are affected only very rarely, resulting from highly disturbed auroral events. In the spring of 1998, due to increasing concern about scintillation of GPS signals during the upcoming solar maximum, the Space Shuttle Program began to assess the impact of scintillation on Collins Miniaturized Airborne GPS Receiver (MAGR) units that are to replace Tactical Air Control and Navigation (TACAN) units on the Space Shuttle orbiters. The Shuttle Program must determine if scintillation effects pose a threat to safety of flight and mission success or require procedural and flight rule changes. Flight controllers in Mission Control must understand scintillation effects on GPS to properly diagnose "off nominal" GPS receiver performance. GPS data from recent Space Shuttle missions indicate that the signals tracked by the Shuttle MAGR manifest scintillation. Scintillation is observed as anomalous noise in velocity measurements lasting for up to 20 minutes on Shuttle orbit passes and are not accounted for in the error budget of the MAGR accuracy parameters. These events are typically coincident with latitude and local time occurrence of previously identified equatorial spread F within about 20 degrees of the magnetic equator. The geographic and seasonal history of these events from ground-based observations and a simple theoretical model, which have potential for predicting events for operational purposes, are reviewed.

  16. Considerations on thermal effects in doped scintillators for dark matter and other rare events searches

    NASA Astrophysics Data System (ADS)

    Chapellier, M.

    2009-08-01

    The scintillation properties of luminescent crystals are well known at room temperature. It is only recently, for the sake of dark matter and rare events searches that the studies have been extended to very low temperatures in the millikelvin range. Some little-known facts on the behaviour of bolometers , and more specifically on scintillating ones, are recalled in a simple manner. A few experiments to better understand them are proposed. The term bolometer is used here for calorimeter. Normally a bolometer will measure a flux of energy whereas a calorimeter measures a deposited energy. The tendency is to use bolometer for both types of measurement. A germanium bolometer does not measure the total energy received, part of it is transformed in ionization energy. The same is true for scintillating bolometer.

  17. The COSINUS project: perspectives of a NaI scintillating calorimeter for dark matter search

    NASA Astrophysics Data System (ADS)

    Angloher, G.; Carniti, P.; Cassina, L.; Gironi, L.; Gotti, C.; Gütlein, A.; Hauff, D.; Maino, M.; Nagorny, S. S.; Pagnanini, L.; Pessina, G.; Petricca, F.; Pirro, S.; Pröbst, F.; Reindl, F.; Schäffner, K.; Schieck, J.; Seidel, W.

    2016-08-01

    The R&D project COSINUS (Cryogenic Observatory for SIgnatures seen in Next-generation Underground Searches) aims to develop a cryogenic scintillating calorimeter using an undoped NaI-crystal as target for direct dark matter search. Dark matter particles interacting with the detector material generate both a phonon signal and scintillation light. While the phonon signal provides a precise determination of the deposited energy, the simultaneously measured scintillation light allows for particle identification on an event-by-event basis, a powerful tool to study material-dependent interactions, and to suppress backgrounds. Using the same target material as the DAMA/LIBRA collaboration, the COSINUS technique may offer a unique possibility to investigate and contribute information to the presently controversial situation in the dark matter sector. We report on the dedicated design planned for the NaI proof-of-principle detector and the objectives of using this detection technique in the light of direct dark matter detection.

  18. Quantitative low-energy ion beam characterization by beam profiling and imaging via scintillation screens

    NASA Astrophysics Data System (ADS)

    Germer, S.; Pietag, F.; Polak, J.; Arnold, T.

    2016-11-01

    This study presents the imaging and characterization of low-current ion beams in the neutralized state monitored via single crystal YAG:Ce (Y3Al5O12) scintillators. To validate the presented beam diagnostic tool, Faraday cup measurements and test etchings were performed. Argon ions with a typical energy of 1.0 keV were emitted from an inductively coupled radio-frequency (13.56 MHz) ion beam source with total currents of some mA. Different beam properties, such as, lateral ion current density, beam divergence angle, and current density in pulsed ion beams have been studied to obtain information about the spatial beam profile and the material removal rate distribution. We observed excellent imaging properties with the scintillation screen and achieved a detailed characterization of the neutralized ion beam. A strong correlation between the scintillator light output, the ion current density, and the material removal rate could be observed.

  19. High-light-output scintillator for photodiode readout: LuI3:Ce3+

    NASA Astrophysics Data System (ADS)

    Birowosuto, M. D.; Dorenbos, P.; van Eijk, C. W. E.; Krämer, K. W.; Güdel, H. U.

    2006-06-01

    In this paper, we investigated the scintillation properties of LuI3:Ce3+. Radioluminescence, light output, energy resolution, and γ-scintillation decay are reported. We find an extremely high light output of 98 000+/-10 000 photons/MeV. LuI3:Ce3+ also gives a very high electron-hole (e-h) pair response when it is coupled with an avalanche photodiode (APD) (92 000+/-9000 e-h pairs/MeV). With an APD, a best energy resolution (full width at half maximum over the peak position) of 3.3%+/-0.3% for 662 keV γ quanta is observed. A combination of an extremely high light output and a good energy resolution makes LuI3:Ce3+ an ideal scintillator for radiation sensor applications. Some drawbacks due to the hygroscopicity and the difficult growth of LuI3:Ce3+ crystals are also discussed.

  20. Simulation of optical interstellar scintillation

    NASA Astrophysics Data System (ADS)

    Habibi, F.; Moniez, M.; Ansari, R.; Rahvar, S.

    2013-04-01

    Aims: Stars twinkle because their light propagates through the atmosphere. The same phenomenon is expected on a longer time scale when the light of remote stars crosses an interstellar turbulent molecular cloud, but it has never been observed at optical wavelengths. The aim of the study described in this paper is to fully simulate the scintillation process, starting from the molecular cloud description as a fractal object, ending with the simulations of fluctuating stellar light curves. Methods: Fast Fourier transforms are first used to simulate fractal clouds. Then, the illumination pattern resulting from the crossing of background star light through these refractive clouds is calculated from a Fresnel integral that also uses fast Fourier transform techniques. Regularisation procedure and computing limitations are discussed, along with the effect of spatial and temporal coherency (source size and wavelength passband). Results: We quantify the expected modulation index of stellar light curves as a function of the turbulence strength - characterised by the diffraction radius Rdiff - and the projected source size, introduce the timing aspects, and establish connections between the light curve observables and the refractive cloud. We extend our discussion to clouds with different structure functions from Kolmogorov-type turbulence. Conclusions: Our study confirms that current telescopes of ~4 m with fast-readout, wide-field detectors have the capability of discovering the first interstellar optical scintillation effects. We also show that this effect should be unambiguously distinguished from any other type of variability through the observation of desynchronised light curves, simultaneously measured by two distant telescopes.

  1. Performance characterization of a new high resolution PET scintillation detector

    PubMed Central

    Foudray, A M K; Olcott, P D

    2013-01-01

    Performance of a new high resolution PET detection concept is presented. In this new concept, annihilation radiation enters the scintillator detectors edge-on. Each detector module comprises two 8 × 8 LYSO scintillator arrays of 0.91 × 0.91 × 1 mm3 crystals coupled to two position-sensitive avalanche photodiodes (PSAPDs) mounted on a flex circuit. Appropriate crystal segmentation allows the recording of all three spatial coordinates of the interaction(s) simultaneously with submillimeter resolution. We report an average energy resolution of 14.6 ± 1.7% for 511 keV photons at FWHM. Coincident time resolution was determined to be 2.98 ± 0.13 ns FWHM on average. The coincidence point spread function (PSF) has an average FWHM of 0.837 ± 0.049 mm (using a 500 μm spherical source) and is uniform across the arrays. Both PSF and coincident time resolution degrade when Compton interactions are included in the data. Different blurring factors were evaluated theoretically, resulting in a calculated PSF of 0.793 mm, in good agreement with the measured value. PMID:20844332

  2. Femtosecond laser ablation of cadmium tungstate for scintillator arrays

    NASA Astrophysics Data System (ADS)

    Richards, S.; Baker, M. A.; Wilson, M. D.; Lohstroh, A.; Seller, P.

    2016-08-01

    Ultrafast pulsed laser ablation has been investigated as a technique to machine CdWO4 single crystal scintillator and segment it into small blocks with the aim of fabricating a 2D high energy X-ray imaging array. Cadmium tungstate (CdWO4) is a brittle transparent scintillator used for the detection of high energy X-rays and γ-rays. A 6 W Yb:KGW Pharos-SP pulsed laser of wavelength 1028 nm was used with a tuneable pulse duration of 10 ps to 190 fs, repetition rate of up to 600 kHz and pulse energies of up to 1 mJ was employed. The effect of varying the pulse duration, pulse energy, pulse overlap and scan pattern on the laser induced damage to the crystals was investigated. A pulse duration of ≥500 fs was found to induce substantial cracking in the material. The laser induced damage was minimised using the following operating parameters: a pulse duration of 190 fs, fluence of 15.3 J cm-2 and employing a serpentine scan pattern with a normalised pulse overlap of 0.8. The surface of the ablated surfaces was studied using scanning electron microscopy, energy dispersive X-ray spectroscopy, atomic force microscopy and X-ray photoelectron spectroscopy. Ablation products were found to contain cadmium tungstate together with different cadmium and tungsten oxides. These laser ablation products could be removed using an ammonium hydroxide treatment.

  3. Cesium hafnium chloride scintillator coupled with an avalanche photodiode photodetector

    NASA Astrophysics Data System (ADS)

    Kurosawa, S.; Kodama, S.; Yokota, Y.; Horiai, T.; Yamaji, A.; Shoji, Y.; Král, R.; Pejchal, J.; Ohashi, Y.; Kamada, K.; Nikl, M.; Yoshikawa, A.

    2017-02-01

    Optical and scintillation properties of pure Cs2HfCl6 (CHC) single crystals were investigated. In particular, light output and energy resolution were measured using a Si avalanche photodiode (Si-APD), since the Si-APD has sufficient quantum efficiency of around 70 % at emission wavelength region of CHC around 420 nm. This CHC single crystal grown using the vertical Bridgeman method showed light output of 37,000± 2,000 photons/MeV . The FWHM energy resolution was determined to be 3.7± 0.5× (E/662 keV)-0.85± 0.03[%], where E [keV] is the gamma-ray energy. Moreover, the temperature dependence of the light output was stable from -5 to 30 oC, while the light output increased below -10 oC.

  4. Maximum-likelihood scintillation detection for EM-CCD based gamma cameras.

    PubMed

    Korevaar, Marc A N; Goorden, Marlies C; Heemskerk, Jan W T; Beekman, Freek J

    2011-08-07

    Gamma cameras based on charge-coupled devices (CCDs) coupled to continuous scintillation crystals can combine a good detection efficiency with high spatial resolutions with the aid of advanced scintillation detection algorithms. A previously developed analytical multi-scale algorithm (MSA) models the depth-dependent light distribution but does not take statistics into account. Here we present and validate a novel statistical maximum-likelihood algorithm (MLA) that combines a realistic light distribution model with an experimentally validated statistical model. The MLA was tested for an electron multiplying CCD optically coupled to CsI(Tl) scintillators of different thicknesses. For (99m)Tc imaging, the spatial resolution (for perpendicular and oblique incidence), energy resolution and signal-to-background counts ratio (SBR) obtained with the MLA were compared with those of the MSA. Compared to the MSA, the MLA improves the energy resolution by more than a factor of 1.6 and the SBR is enhanced by more than a factor of 1.3. For oblique incidence (approximately 45°), the depth-of-interaction corrected spatial resolution is improved by a factor of at least 1.1, while for perpendicular incidence the MLA resolution does not consistently differ significantly from the MSA result for all tested scintillator thicknesses. For the thickest scintillator (3 mm, interaction probability 66% at 141 keV) a spatial resolution (perpendicular incidence) of 147 µm full width at half maximum (FWHM) was obtained with an energy resolution of 35.2% FWHM. These results of the MLA were achieved without prior calibration of scintillations as is needed for many statistical scintillation detection algorithms. We conclude that the MLA significantly improves the gamma camera performance compared to the MSA.

  5. A Monte Carlo investigation of Swank noise for thick, segmented, crystalline scintillators for radiotherapy imaging

    SciTech Connect

    Wang Yi; Antonuk, Larry E.; El-Mohri, Youcef; Zhao Qihua

    2009-07-15

    Thick, segmented scintillating detectors, consisting of 2D matrices of scintillator crystals separated by optically opaque septal walls, hold considerable potential for significantly improving the performance of megavoltage (MV) active matrix, flat-panel imagers (AMFPIs). Initial simulation studies of the radiation transport properties of segmented detectors have indicated the possibility of significant improvement in DQE compared to conventional MV AMFPIs based on phosphor screen detectors. It is therefore interesting to investigate how the generation and transport of secondary optical photons affect the DQE performance of such segmented detectors. One effect that can degrade DQE performance is optical Swank noise (quantified by the optical Swank factor I{sub opt}), which is induced by depth-dependent variations in optical gain. In this study, Monte Carlo simulations of radiation and optical transport have been used to examine I{sub opt} and zero-frequency DQE for segmented CsI:Tl and BGO detectors at different thicknesses and element-to-element pitches. For these detectors, I{sub opt} and DQE were studied as a function of various optical parameters, including absorption and scattering in the scintillator, absorption at the top reflector and septal walls, as well as scattering at the side surfaces of the scintillator crystals. The results indicate that I{sub opt} and DQE are only weakly affected by absorption and scattering in the scintillator, as well as by absorption at the top reflector. However, in some cases, these metrics were found to be significantly degraded by absorption at the septal walls and scattering at the scintillator side surfaces. Moreover, such degradations are more significant for detectors with greater thickness or smaller element pitch. At 1.016 mm pitch and with optimized optical properties, 40 mm thick segmented CsI:Tl and BGO detectors are predicted to provide DQE values of {approx}29% and 42%, corresponding to improvement by factors of

  6. A Monte Carlo investigation of Swank noise for thick, segmented, crystalline scintillators for radiotherapy imaging

    PubMed Central

    Wang, Yi; Antonuk, Larry E.; El-Mohri, Youcef; Zhao, Qihua

    2009-01-01

    Thick, segmented scintillating detectors, consisting of 2D matrices of scintillator crystals separated by optically opaque septal walls, hold considerable potential for significantly improving the performance of megavoltage (MV) active matrix, flat-panel imagers (AMFPIs). Initial simulation studies of the radiation transport properties of segmented detectors have indicated the possibility of significant improvement in DQE compared to conventional MV AMFPIs based on phosphor screen detectors. It is therefore interesting to investigate how the generation and transport of secondary optical photons affect the DQE performance of such segmented detectors. One effect that can degrade DQE performance is optical Swank noise (quantified by the optical Swank factor Iopt), which is induced by depth-dependent variations in optical gain. In this study, Monte Carlo simulations of radiation and optical transport have been used to examine Iopt and zero-frequency DQE for segmented CsI:Tl and BGO detectors at different thicknesses and element-to-element pitches. For these detectors, Iopt and DQE were studied as a function of various optical parameters, including absorption and scattering in the scintillator, absorption at the top reflector and septal walls, as well as scattering at the side surfaces of the scintillator crystals. The results indicate that Iopt and DQE are only weakly affected by absorption and scattering in the scintillator, as well as by absorption at the top reflector. However, in some cases, these metrics were found to be significantly degraded by absorption at the septal walls and scattering at the scintillator side surfaces. Moreover, such degradations are more significant for detectors with greater thickness or smaller element pitch. At 1.016 mm pitch and with optimized optical properties, 40 mm thick segmented CsI:Tl and BGO detectors are predicted to provide DQE values of ∼29% and 42%, corresponding to improvement by factors of ∼29 and 42, respectively

  7. Measurement of radiation damage of water-based liquid scintillator and liquid scintillator

    DOE PAGES

    Bignell, L. J.; Diwan, M. V.; Hans, S.; ...

    2015-10-19

    Liquid scintillating phantoms have been proposed as a means to perform real-time 3D dosimetry for proton therapy treatment plan verification. We have studied what effect radiation damage to the scintillator will have upon this application. We have performed measurements of the degradation of the light yield and optical attenuation length of liquid scintillator and water-based liquid scintillator after irradiation by 201 MeV proton beams that deposited doses of approximately 52 Gy, 300 Gy, and 800 Gy in the scintillator. Liquid scintillator and water-based liquid scintillator (composed of 5% scintillating phase) exhibit light yield reductions of 1.74 ± 0.55 % andmore » 1.31 ± 0.59 % after ≈ 800 Gy of proton dose, respectively. Some increased optical attenuation was observed in the irradiated samples, the measured reduction to the light yield is also due to damage to the scintillation light production. Based on our results and conservative estimates of the expected dose in a clinical context, a scintillating phantom used for proton therapy treatment plan verification would exhibit a systematic light yield reduction of approximately 0.1% after a year of operation.« less

  8. Measurement of radiation damage of water-based liquid scintillator and liquid scintillator

    SciTech Connect

    Bignell, L. J.; Diwan, M. V.; Hans, S.; Jaffe, D. E.; Rosero, R.; Vigdor, S.; Viren, B.; Worcester, E.; Yeh, M.; Zhang, C.

    2015-10-19

    Liquid scintillating phantoms have been proposed as a means to perform real-time 3D dosimetry for proton therapy treatment plan verification. We have studied what effect radiation damage to the scintillator will have upon this application. We have performed measurements of the degradation of the light yield and optical attenuation length of liquid scintillator and water-based liquid scintillator after irradiation by 201 MeV proton beams that deposited doses of approximately 52 Gy, 300 Gy, and 800 Gy in the scintillator. Liquid scintillator and water-based liquid scintillator (composed of 5% scintillating phase) exhibit light yield reductions of 1.74 ± 0.55 % and 1.31 ± 0.59 % after ≈ 800 Gy of proton dose, respectively. Some increased optical attenuation was observed in the irradiated samples, the measured reduction to the light yield is also due to damage to the scintillation light production. Based on our results and conservative estimates of the expected dose in a clinical context, a scintillating phantom used for proton therapy treatment plan verification would exhibit a systematic light yield reduction of approximately 0.1% after a year of operation.

  9. Investigation of radiation detection properties of CRY-018 and CRY-019 scintillators for medical imaging

    NASA Astrophysics Data System (ADS)

    Pani, R.; Colarieti-Tosti, M.; Cinti, M. N.; Polito, C.; Trigila, C.; Ridolfi, S.

    2016-09-01

    During the last years the research for new scintillation crystals has been crucial for the improvement of imaging performance in nuclear medicine applications. Crytur company has recently released two new scintillators named CRY-018 and CRY-019 which are non hygroscopic, have short decay time and low refraction index. They represent the ideal candidates to substitute NaI:Tl and BGO crystals in future PET ad SPECT applications. The purpose of this work is to characterize this unknown crystals, look for possible applications in imaging for nuclear medicine. The results of this work were compared with the results obtained with a LaBr3:ce scintillation crystal. This particular crystal is used as a comparison benchmark because of its strong linear pulse height uniformity response and high energy resolution. Measurements have been performed with a high count rate which is typical for medical applications. Irradiation of the crystals have been performed in three different geometries and in a photon energy range suitable with SPECT and PET applications. The experimental results identify the CRY-018 as an Yttrium and Silicon mixture and the CRY-019 with as Lutetium and Silicon one. Moreover a light yield of about 45% of LaBr3 one, was obtained for both the CRY-018 and CRY-019. This is one of the higher light yield between most of the scintillation crystals usually used in nuclear medicine. Both crystals are characterized by a non-proportionality in the pulse height linearity response. Energy resolutions of 7.4% for CRY-018 and 8.4% for CRY-019 at 661 keV, have been measured. The intrinsic component of the energy resolution has been esteemed for all three scintillators. An intrinsic detection efficiency of about 45% at 122 keV for CRY-018 and 14% at 661 keV for CRY-019 has been measured. Compared with LaBr3:Ce efficiency, which is highly deteriorated by the coating required by the hygroscopicity, CRY-018 and CRY-019 are really interesting considering that these two samples

  10. Cryogenic phonon-scintillation detectors with PMT readout for rare event search experiments

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Lin, J.; Mikhailik, V. B.; Kraus, H.

    2016-06-01

    Cryogenic phonon-scintillation detectors (CPSD) for rare event search experiments require reliable, efficient and robust photon detectors that can resolve individual photons in a scintillation event. We report on a cryogenic detector containing a scintillating crystal, equipped with an NTD-Ge phonon sensor and a photon detector based on a low-temperature photomultiplier tube (PMT) that is powered by a Cockcroft-Walton generator. Here we present results from the characterisation of two detector modules, one with CaWO4, the other with CaMoO4 as scintillator. The energy resolutions (FWHM) at 122.1 keV for the scintillation/PMT channel are 19.9% and 29.7% respectively for CaWO4 and CaMoO4 while the energy resolutions (FWHM) for the phonon channels are 2.17 keV (1.8%) and 0.97 keV (0.79%). These characteristics compare favourably with other CPSDs currently used in cryogenic rare-event search experiments. The detection module with PMT readout benefits from the implementation of a well-understood, reliable, and commercially available component and improved time resolution, while retaining the major advantages of conventional CPSD, such as high sensitivity, resolving power and discrimination ability.

  11. Scintillation Detectors for Radiation-Hard Electromagnetic Calorimeters

    NASA Astrophysics Data System (ADS)

    Löhner, H.

    2005-02-01

    For the application in the compact and radiation hard electromagnetic (EM) calorimeter in the PANDA detection system at the new GSI facility, we have started to advance scintillation crystals and the light detection technique. PANDA is the universal internal-target detection system for charmonium spectroscopy and the search for glue-balls and hybrid states in antiproton annihilations. In particular, the large dynamic range from several GeV down to a detection threshold of some MeV for EM radiation and the expected high background rate of neutrons and ions will impose severe requirements on crystals and light sensors. In the magnetic environment of tracking devices the use of Avalanche Photodiodes (APD's) is preferred. In order to achieve suitable resolution for low energy hadrons and photons, the light output of crystals will have to be improved by special production techniques, activation and doping. These procedures might have implications for the radiation hardness. We report on measurements of signal response and radiation damage in crystals of PbWO4 and BGO both from the BTCP (Russia) and SICCAS (China) production sites. Beams of protons, electrons and photons have been applied while detectors with either phototube or APD readout were operated in the range from room temperature to -20°C. Results on light yield and energy resolution are presented. We report on the reduction of light transmission after proton irradiation and results from electron-spin resonance studies on irradiated crystals to analyse the cause of radiation damage.

  12. Equatorial scintillations: advances since ISEA-6

    SciTech Connect

    Not Available

    1985-01-01

    Our understanding of the morphology of equatorial scintillations has advanced due to more intensive observations at the equatorial anomaly locations in the different longitude zones. The unmistakable effect of the sunspot cycle in controlling irregularity belt width and electron concentration responsible for strong scintillation in the controlling the magnitude of scintillations has been recognized by interpreting scintillation observations inthe light of realistic models of total electron content at various longitudes. A hypothesis based on the alignment of the solar terminator with the geomagnetic flux tubes as an indicator of enhanced scintillation occurrence and another based on the influence of a transequatorial thermospheric neutral wind have been postulated to describe the observed longitudinal variation. A distinct class of equatorial irregularities known as the bottomside sinusoidal (BSS) type was identified. These irregularities occur in very large patches, sometimes in excess of several thousand kilometers in the E-W direction and are associated with frequency spread on ionograms. Scintillations caused by such irregularities exist only in the VHF band, exhibit Fresnel oscillations in intensity spectra and are found to give rise to extremely long durations (approx. several hours) of uninterrrupted scintillations.

  13. Scintillation Breakdowns in Chip Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2008-01-01

    Scintillations in solid tantalum capacitors are momentarily local breakdowns terminated by a self-healing or conversion to a high-resistive state of the manganese oxide cathode. This conversion effectively caps the defective area of the tantalum pentoxide dielectric and prevents short-circuit failures. Typically, this type of breakdown has no immediate catastrophic consequences and is often considered as nuisance rather than a failure. Scintillation breakdowns likely do not affect failures of parts under surge current conditions, and so-called "proofing" of tantalum chip capacitors, which is a controllable exposure of the part after soldering to voltages slightly higher than the operating voltage to verify that possible scintillations are self-healed, has been shown to improve the quality of the parts. However, no in-depth studies of the effect of scintillations on reliability of tantalum capacitors have been performed so far. KEMET is using scintillation breakdown testing as a tool for assessing process improvements and to compare quality of different manufacturing lots. Nevertheless, the relationship between failures and scintillation breakdowns is not clear, and this test is not considered as suitable for lot acceptance testing. In this work, scintillation breakdowns in different military-graded and commercial tantalum capacitors were characterized and related to the rated voltages and to life test failures. A model for assessment of times to failure, based on distributions of breakdown voltages, and accelerating factors of life testing are discussed.

  14. Forecasting scintillation activity and equatorial spread F

    NASA Astrophysics Data System (ADS)

    Anderson, David N.; Redmon, Robert J.

    2017-03-01

    When transionospheric radio waves propagate through an irregular ionosphere with plasma depletions or "bubbles," they are subject to sporadic enhancement and fading, which is referred to as scintillation. Communication and navigation systems may be subject to these detrimental effects if the scintillation is strong enough. It is critical to have knowledge of the current ionospheric conditions so that system operators can distinguish between the natural radio environment and system-induced failures. In this paper we briefly describe the Forecasting Ionospheric Real-time Scintillation Tool UHF scintillation forecasting technique, which utilizes the observed characteristic parameter h'F from a ground-based, ionospheric sounder near the magnetic equator. The prereversal enhancement in vertical E × B drift velocity after sunset is the prime driver for creating plasma depletions and bubbles. In addition, there exists a "threshold" in the h'F value at 1930 LT, h'Fthr, such that, on any given evening, if h'F is significantly above h'Fthr, then scintillation activity is likely to occur, and if it is below h'Fthr, scintillation activity is unlikely to occur. We use this technique to explain the lack of scintillation activity prior to the Halloween storm in October 2003 in the Peruvian longitude sector. In addition, we have carried out a study which forecasts the occurrence or nonoccurrence of equatorial spread F (ESF), on a night-to-night basis, in five longitude sectors. The overall forecasting success is greater than 80% for each of the five longitude sectors.

  15. Comparative studies of monoclinic and orthorhombic WO3 films used for hydrogen sensor fabrication on SiC crystal

    NASA Astrophysics Data System (ADS)

    Zuev, V. V.; Grigoriev, S. N.; Romanov, R. I.; Fominski, V. Y.; Volosova, M. A.; Demin, M. V.

    2016-09-01

    Amorphous WOx films were prepared on the SiC crystal by using two different methods, namely, reactive pulsed laser deposition (RPLD) and reactive deposition by ion sputtering (RDIS). After deposition, the WOx films were annealed in an air. The RISD film possessed a m-WO3 structure and consisted of closely packed microcrystals. Localized swelling of the films and micro-hills growth did not destroy dense crystal packing. RPLD film had layered β-WO3 structure with relatively smooth surface. Smoothness of the films were destroyed by localized swelling and the micro-openings formation was observed. Comparative study of m-WO3/SiC, Pt/m-WO3/SiC, and P-WO3/SiC samples shows that structural characteristics of the WO3 films strongly influence on the voltage/current response as well as on the rate of current growth during H2 detection at elevated temperatures.

  16. Modeling scintillator-photodiodes as detectors for megavoltage CT.

    PubMed

    Monajemi, T T; Steciw, S; Fallone, B G; Rathee, S

    2004-05-01

    The use of cadmium tungstate (CdWO4) and cesium iodide [CsI(Tl)] scintillation detectors is studied in megavoltage computed tomography (MVCT). A model describing the signal acquired from a scintillation detector has been developed which contains two steps: (1) the calculation of the energy deposited in the crystal due to MeV photons using the EGSnrc Monte Carlo code; and (2) the transport of the optical photons generated in the crystal voxels to photodiodes using the optical Monte Carlo code DETECT2000. The measured detector signals in single CdWO4 and CsI(Tl) scintillation crystals of base 0.275 x 0.8 cm2 and heights 0.4, 1, 1.2, 1.6 and 2 cm were, generally, in good agreement with the signals calculated with the model. A prototype detector array which contains 8 CdWO4 crystals, each 0.275 x 0.8 x 1 cm3, in contact with a 16-element array of photodiodes was built. The measured attenuation of a Cobalt-60 beam as a function of solid water thickness behaves linearly. The frequency dependent modulation transfer function [MTF(f)], noise power spectrum [NPS(f)], and detective quantum efficiency [DQE(f)] were measured for 1.25 MeV photons (in a Cobalt-60 beam). For 6 MV photons, only the MTF(f) was measured from a linear accelerator, where large pulse-to-pulse fluctuations in the output of the linear accelerator did not allow the measurement of the NPS(f). A two-step Monte Carlo simulation was used to model the detector's MTF(f), NPS(f) and DQE(f). The DQE(0) of the detector array was found to be 26% and 19% for 1.25 MeV and 6 MV photons, respectively. For 1.25 MeV photons, the maximum discrepancies between the measured and modeled MTF(f), relative NPS(f) and the DQE(f) were found to be 1.5%, 1.2%, and 1.9%, respectively. For the 6 MV beam, the maximum discrepancy between the modeled and the measured MTF(f) was found to be 2.5%. The modeling is sufficiently accurate for designing appropriate detectors for MVCT.

  17. Advanced plastic scintillators for fast neutron discrimination

    SciTech Connect

    Feng, Patrick L; Anstey, Mitchell; Doty, F. Patrick; Mengesha, Wondwosen

    2014-09-01

    The present work addresses the need for solid-state, fast neutron discriminating scintillators that possess higher light yields and faster decay kinetics than existing organic scintillators. These respective attributes are of critical importance for improving the gamma-rejection capabilities and increasing the neutron discrimination performance under high-rate conditions. Two key applications that will benefit from these improvements include large-volume passive detection scenarios as well as active interrogation search for special nuclear materials. Molecular design principles were employed throughout this work, resulting in synthetically tailored materials that possess the targeted scintillation properties.

  18. Radiation effects in intrinsic 3HF scintillator

    NASA Astrophysics Data System (ADS)

    Bross, Alan D.; Pla-Dalmau, Anna

    1993-04-01

    Test scintillators of the type 3-hydroxyflavone (3HF) plus polystyrene were prepared with 3HF doping concentrations between 0.05% and 2.0% by weight. Ternary scintillators of the type p-terphenyl(1%)+3HF(0.01%) and p-terphenyl(1%)+3HF(0.1%) in polystyrene were also prepared. The scintillation light yield is given for all samples. Representative fluorescence and transmittance spectra are also shown. Changes in light yield, transmittance, and fluorescence are shown for 60Co irradiations with integrated doses of 10 and 30 Mrad.

  19. Scintillation counter with WLS fiber readout

    NASA Astrophysics Data System (ADS)

    Bukin, D. A.; Druzhinin, V. P.; Golubev, V. B.; Serednyakov, S. I.

    1997-02-01

    The parameters of a cylindrical scintillation counter of 126 mm in diameter and 370 mm in length with wavelength shifter (WLS) fiber readout are presented. The fibers are glued into machined grooves along the scintillator. Light from both ends of the WLS fibers is transmitted to separate photomultipliers by 1 m long clear optical fibers. The average total signal, collected from both sides of the counter is equivalent to 8 photoelectrons per minimum ionizing particle. The described cylindrical scintillation counter is a part of inner system of collider detector SND.

  20. Scintillating Track Image Camera-SCITIC

    NASA Astrophysics Data System (ADS)

    Sato, Akira; Asai, Jyunkichi; Ieiri, Masaharu; Iwata, Soma; Kadowaki, Tetsuhito; Kurosawa, Maki; Nagae, Tomohumi; Nakai, Kozi

    2004-04-01

    A new type of track detector, scintillating track image camera (SCITIC) has been developed. Scintillating track images of particles in a scintillator are focused by an optical lens system on a photocathode on image intesifier tube (IIT). The image signals are amplified by an IIT-cascade and stored by a CCD camera. The performance of the detector has been tested with cosmic-ray muons and with pion- and proton-beams from the KEK 12-GeV proton synchrotron. Data of the test experiments have shown promising features of SCITIC as a triggerable track detector with a variety of possibilities.