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The Solidification Using a Baffle in Sealed Ampoules (SUBSA) hardware being installed by NASA astronaut Peggy Whitson during Expedition 5. The SUBSA Furnace and Inserts investigation includes modernized data acquisition, high definition video and communication interfaces. Credit: NASA Research into crystal growth in microgravity was one of the earliest investigations conducted aboard the International Space Station and is continued to this day. The unique microgravity environment of space provides an ideal setting for producing crystals that are more perfect than their terrestrial-grown counterparts. The Crystal Growth of Cs2LiYCl6:Ce Scintillators in Microgravity (CLYC-Crystal Growth), a Center for the Advancement of Science in Space (CASIS)-sponsored investigation, will study the potential benefits of growing the CYLC crystal in microgravity. The CLYC crystal is a special kind of multicomponent crystal system used to make scintillator radiation detectors, a device that is sensitive to both gamma rays and neutrons. "It's a spectroscopic crystal, which means, using this crystal, we can detect the presence and intensity of radiation, as well as identify which isotopes emit radiation by measuring the energy," said Dr. Alexei Churilov, primary investigator and senior scientist at Radiation Monitoring Devices Inc. (RMD). The CLYC crystal is produced as a commercial product by RMD and is largely used to detect and differentiate both harmful and harmless levels of radiation. The crystal's main application is homeland security as a method of detected smuggled nuclear materials, but may also be used for oil and gas exploration, medical imaging, particle and space physics and scientific instruments. However, the Earth-grown crystals have shown defects such as cracks, grain boundaries and inclusions, incidents which scientists like Churilov hope to eliminate by using the space station's microgravity environment as a growth habitat. Research has shown that many, though not all, crystals benefit from growth in microgravity. Although the reasoning behind this phenomena is still being investigated, research points to the lack of buoyancy-induced convection, which affects transport of molecules in the crystal. "Our ultimate goal is to study the growth of CLYC in microgravity without the interference of convection and to improve the production of the crystal on Earth," said Churilov. The research for the CLYC Crystal Growth investigation will be conducted within the Solidification Using a Baffle in Sealed Ampoules Furnaces and Inserts (SUBSA Furnaces and Inserts). SUBSA helps researchers advance the understanding of processes involved in semiconductor crystal growth. It offers a gradient freeze furnace for materials science investigations. SUBSA was originally operated aboard the space station in 2002, the SUBSA hardware has been modernized and updated with data acquisition, high resolution video and communication interfaces. During the investigation, four crystal growth runs will be conducted aboard the space station and then in the ground-based SUBSA furnaces, giving researchers a view into the gravitational effect on their growth. Once the investigation is complete, the space-grown crystals will be compared against their counterparts on Earth and tested for imperfections and effectiveness as radiation detectors. Although microgravity can't be mimicked or reproduced on the ground, results from the investigation will provide information about which crystal methods to use on Earth, how to improve ampoule and furnace design and which crystal growth parameters to change in pursuit of a more perfect crystallization process. Though the total weight of the CLYC Crystal Growth investigation is small, only a few kilograms together with packaging, the benefits can be immense as the data gathered during the investigation will be put to immediate use in the production of CLYC crystals.

Gentile T.R.,U.S. National Institute of Standards and Technology | Bales M.,University of Michigan | Arp U.,U.S. National Institute of Standards and Technology | Dong B.,Sotera Defense Solutions | Farrell R.,RMD Inc.
Review of Scientific Instruments | Year: 2012

For an experiment to study neutron radiative beta-decay, we operated large area avalanche photodiodes (APDs) near liquid nitrogen temperature to detect x rays with energies between 0.2 keV and 20 keV. Whereas there are numerous reports of x ray spectrometry using APDs at energies above 1 keV, operation near liquid nitrogen temperature allowed us to reach a nominal threshold of 0.1 keV. However, due to the short penetration depth of x rays below 1 keV, the pulse height spectrum of the APD become complex. We studied the response using monochromatic x ray beams and employed phenomenological fits of the pulse height spectrum to model the measurement of a continuum spectrum from a synchrotron. In addition, the measured pulse height spectrum was modelled using a profile for the variation in efficiency of collection of photoelectrons with depth into the APD. The best results are obtained with the collection efficiency model. © 2012 American Institute of Physics.

Trojan-Piegza J.,Boston University | Trojan-Piegza J.,Wrocław University | Glodo J.,RMD Inc. | Sarin V.K.,Boston University
Radiation Measurements | Year: 2010

A series of composites of CaF2(Eu2+) and LiF with different Ca/Li ratios were fabricated via liquid phase consolidation. Luminescent properties of these samples were investigated. Radioluminescence shows the typical Eu2+ blue emission in all the compositions. The energy spectra measured under γ and neutron irradiation indicates that the most promising composition for neutron detection is the eutectic. © 2010 Elsevier Ltd. All rights reserved.

Gentile T.R.,U.S. National Institute of Standards and Technology | Bass C.D.,U.S. National Institute of Standards and Technology | Nico J.S.,U.S. National Institute of Standards and Technology | Breuer H.,U.S. National Institute of Standards and Technology | And 2 more authors.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2011

We present results for detection of X-rays by large area avalanche photodiodes (APDs) in strong magnetic fields and at cryogenic temperatures. Whereas at room temperature we observe essentially no effects on the response, at cryogenic temperature we observe significant distortion when the magnetic field is in the plane of the APD surface (and thus perpendicular to the electric field in the APD). At all temperatures, effects are minor when the magnetic field is normal to the APD surface (and thus parallel to the electric field in the APD). We performed measurements of the response of an APD to illumination by X-rays in fields between 0 and 4.6 T, for temperatures between 77 and 250 K. Measurements were performed using 241Am and 55Fe sources, and 1.5 keV X-rays produced by aluminum fluorescence. The data indicate that the effects are associated with those X-rays that are absorbed in the drift region of the APD. © 2010 Elsevier B.V.

Phillips D.J.,Naval Postgraduate School, Monterey | Blaine K.E.,U.S. Military Academy | Cirignano L.J.,RMD Inc. | Ciampi G.,RMD Inc. | Haegel N.M.,Naval Postgraduate School, Monterey
IEEE Transactions on Nuclear Science | Year: 2012

Nonuniformity in charge transport properties is a limiting factor in energy resolution of radiation detectors. In this paper, we investigate variations in the low temperature ambipolar diffusion length and the mobility-lifetime [μτ] product in bulk doped TlBr using cathodoluminescence (CL) and transport imaging. One TlBr crystal was doped with sodium (Na), aluminum (Al), and silver (Ag). A second TlBr crystal was doped with copper (Cu), iron (Fe), and zinc (Zn). We report the first low temperature high resolution CL spectroscopy and mapping in bulk doped TlBr, showing spatial variation in recombination luminescence on a scale of ∼ 10 μ. Transport imaging is applied to quantify these variations in TlBr at 5 K. Ambipolar diffusion lengths and μT products, dominated by the transport of holes, are mapped across a 40μm segment of TlBr at a resolution of 2μm. Ambipolar diffusion lengths are found to vary between 4.6μm and 11.2μm, on a spatial scale comparable to the variation observed in the CL map. © 2012 IEEE.

Kim H.,RMD Inc. | Kargar A.,RMD Inc. | Cirignano L.,RMD Inc. | Churilov A.,RMD Inc. | And 4 more authors.
IEEE Transactions on Nuclear Science | Year: 2012

In recent years, progress in processing and crystal growth methods have led to a significant increase in the mobility-lifetime product of electrons in thallium bromide (TlBr). This has enabled single carrier collection devices with thickness greater than 1-cm to be fabricated. In this paper we report on our latest results from pixellated devices with depth correction as well as our initial results with Frisch collar devices. After applying depth corrections, energy resolution of approximately 2% (FWHM at 662 keV) was obtained from a 13-mm thick TlBr array operated at-18°C and under continuous bias and irradiation for more than one month. Energy resolution of 2.4% was obtained at room temperature with an 8.4-mm thick TlBr Frisch collar device. © 2012 IEEE.

Sengupta D.,Stanford University | Miller S.,RMD Inc. | Marton Z.,RMD Inc. | Chin F.,Stanford University | And 2 more authors.
Advanced Healthcare Materials | Year: 2015

The performance of a new thin-film Lu2O3:Eu scintillator for single-cell radionuclide imaging is investigated. Imaging the metabolic properties of heterogeneous cell populations in real time is an important challenge with clinical implications. An innovative technique called radioluminescence microscopy has been developed to quantitatively and sensitively measure radionuclide uptake in single cells. The most important component of this technique is the scintillator, which converts the energy released during radioactive decay into luminescent signals. The sensitivity and spatial resolution of the imaging system depend critically on the characteristics of the scintillator, that is, the material used and its geometrical configuration. Scintillators fabricated using conventional methods are relatively thick and therefore do not provide optimal spatial resolution. A thin-film Lu2O3:Eu scintillator is compared to a conventional 500 μm thick CdWO4 scintillator for radioluminescence imaging. Despite its thinness, the unique scintillation properties of the Lu2O3:Eu scintillator allow us to capture single-positron decays with fourfold higher sensitivity, which is a significant achievement. The thin-film Lu2O3:Eu scintillators also yield radioluminescence images where individual cells appear smaller and better resolved on average than with the CdWO4 scintillators. Coupled with the thin-film scintillator technology, radioluminescence microscopy can yield valuable and clinically relevant data on the metabolism of single cells. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tian L.,Massachusetts Institute of Technology | Tian L.,University of California at Berkeley | Petruccelli J.C.,Massachusetts Institute of Technology | Miao Q.,Massachusetts Institute of Technology | And 4 more authors.
Optics Letters | Year: 2013

We develop and implement a compressive reconstruction method for tomographic recovery of refractive index distribution for weakly attenuating objects in a microfocus x-ray system. This is achieved through the development of a discretized operator modeling both the transport of intensity equation and the x-ray transform that is suitable for iterative reconstruction techniques. © 2013 Optical Society of America.

Rmd Llc | Date: 2012-07-24

heat and acoustical composite insulating shield for automobiles, trucks, boats, watercraft, HVAC, appliances and machinery; insulating tapes; adhesive sealant and caulking compound.

WATERTOWN, Mass., Nov. 2, 2016 /PRNewswire/ -- Dynasil Corporation of America (NASDAQ: DYSL) today announced that its subsidiary, RMD Inc., will be supplying Thermo Fisher Scientific with packaged solid state detectors based on RMD's Cs2LiYCl6:Ce (CLYC) scintillation crystals for use in...

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