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Sample records for detectors radiation

  1. Radiation detector

    DOEpatents

    Fultz, B.T.

    1980-12-05

    Apparatus is provided for detecting radiation such as gamma rays and x-rays generated in backscatter Moessbauer effect spectroscopy and x-ray spectrometry, which has a large window for detecting radiation emanating over a wide solid angle from a specimen and which generates substantially the same output pulse height for monoenergetic radiation that passes through any portion of the detection chamber. The apparatus includes a substantially toroidal chamber with conductive walls forming a cathode, and a wire anode extending in a circle within the chamber with the anode lying closer to the inner side of the toroid which has the least diameter than to the outer side. The placement of the anode produces an electric field, in a region close to the anode, which has substantially the same gradient in all directions extending radially from the anode, so that the number of avalanche electrons generated by ionizing radiation is independent of the path of the radiation through the chamber.

  2. Radiation detector

    DOEpatents

    Fultz, Brent T. (Berkeley, CA)

    1983-01-01

    Apparatus is provided for detecting radiation such as gamma rays and X-rays generated in backscatter Mossbauer effect spectroscopy and X-ray spectrometry, which has a large "window" for detecting radiation emanating over a wide solid angle from a specimen and which generates substantially the same output pulse height for monoenergetic radiation that passes through any portion of the detection chamber. The apparatus includes a substantially toroidal chamber with conductive walls forming a cathode, and a wire anode extending in a circle within the chamber with the anode lying closer to the inner side of the toroid which has the least diameter than to the outer side. The placement of the anode produces an electric field, in a region close to the anode, which has substantially the same gradient in all directions extending radially from the anode, so that the number of avalanche electrons generated by ionizing radiation is independent of the path of the radiation through the chamber.

  3. Adaptors for radiation detectors

    SciTech Connect

    Livesay, Ronald Jason

    2014-04-22

    Described herein are adaptors and other devices for radiation detectors that can be used to make accurate spectral measurements of both small and large bulk sources of radioactivity, such as building structures, soils, vessels, large equipment, and liquid bodies. Some exemplary devices comprise an adaptor for a radiation detector, wherein the adaptor can be configured to collimate radiation passing through the adapter from an external radiation source to the radiation detector and the adaptor can be configured to enclose a radiation source within the adapter to allow the radiation detector to measure radiation emitted from the enclosed radiation source.

  4. Adaptors for radiation detectors

    DOEpatents

    Livesay, Ronald Jason

    2015-07-28

    Described herein are adaptors and other devices for radiation detectors that can be used to make accurate spectral measurements of both small and large bulk sources of radioactivity, such as building structures, soils, vessels, large equipment, and liquid bodies. Some exemplary devices comprise an adaptor for a radiation detector, wherein the adaptor can be configured to collimate radiation passing through the adapter from an external radiation source to the radiation detector and the adaptor can be configured to enclose a radiation source within the adapter to allow the radiation detector to measure radiation emitted from the enclosed radiation source.

  5. Tin Can Radiation Detector.

    ERIC Educational Resources Information Center

    Crull, John L.

    1986-01-01

    Provides instructions for making tin can radiation detectors from empty aluminum cans, aluminum foil, clear plastic, copper wire, silica gel, and fine, unwaxed dental floss put together with tape or glue. Also provides suggestions for activities using the detectors. (JN)

  6. Underwater radiation detector

    DOEpatents

    Kruse, Lyle W. (Albuquerque, NM); McKnight, Richard P. (Albuquerque, NM)

    1986-01-01

    A detector apparatus for differentiating between gamma and neutron radiation is provided. The detector includes a pair of differentially shielded Geiger-Mueller tubes. The first tube is wrapped in silver foil and the second tube is wrapped in lead foil. Both the silver and lead foils allow the passage of gamma rays at a constant rate in a gamma ray only field. When neutrons are present, however, the silver activates and emits beta radiation that is also detected by the silver wrapped Geiger-Mueller tube while the radiation detected by the lead wrapped Geiger-Mueller tube remains constant. The amount of radiation impinging on the separate Geiger-Mueller tubes is then correlated in order to distinguish between the neutron and gamma radiations.

  7. Radiation Detectors and Art

    NASA Astrophysics Data System (ADS)

    Denker, Andrea

    The use of radiation detectors in the analysis of art objects represents a very special application in a true interdisciplinary field. Radiation detectors employed in this field detect, e.g., x-rays, ?-rays, ? particles, and protons. Analyzed materials range from stones, metals, over porcelain to paintings. The available nondestructive and noninvasive analytical methods cover a broad range of techniques. Hence, for the sake of brevity, this chapter will concentrate on few techniques: Proton Induced X-ray Emission (PIXE) and Proton Induced ?-ray Emission (PIGE).

  8. Amorphous silicon radiation detectors

    DOEpatents

    Street, Robert A. (Palo Alto, CA); Perez-Mendez, Victor (Berkeley, CA); Kaplan, Selig N. (El Cerrito, CA)

    1992-01-01

    Hydrogenated amorphous silicon radiation detector devices having enhanced signal are disclosed. Specifically provided are transversely oriented electrode layers and layered detector configurations of amorphous silicon, the structure of which allow high electric fields upon application of a bias thereby beneficially resulting in a reduction in noise from contact injection and an increase in signal including avalanche multiplication and gain of the signal produced by incoming high energy radiation. These enhanced radiation sensitive devices can be used as measuring and detection means for visible light, low energy photons and high energy ionizing particles such as electrons, x-rays, alpha particles, beta particles and gamma radiation. Particular utility of the device is disclosed for precision powder crystallography and biological identification.

  9. Ionizing radiation detector

    DOEpatents

    Thacker, Louis H. (Knoxville, TN)

    1990-01-01

    An ionizing radiation detector is provided which is based on the principle of analog electronic integration of radiation sensor currents in the sub-pico to nano ampere range between fixed voltage switching thresholds with automatic voltage reversal each time the appropriate threshold is reached. The thresholds are provided by a first NAND gate Schmitt trigger which is coupled with a second NAND gate Schmitt trigger operating in an alternate switching state from the first gate to turn either a visible or audible indicating device on and off in response to the gate switching rate which is indicative of the level of radiation being sensed. The detector can be configured as a small, personal radiation dosimeter which is simple to operate and responsive over a dynamic range of at least 0.01 to 1000 R/hr.

  10. Amorphous silicon radiation detectors

    DOEpatents

    Street, R.A.; Perez-Mendez, V.; Kaplan, S.N.

    1992-11-17

    Hydrogenated amorphous silicon radiation detector devices having enhanced signal are disclosed. Specifically provided are transversely oriented electrode layers and layered detector configurations of amorphous silicon, the structure of which allow high electric fields upon application of a bias thereby beneficially resulting in a reduction in noise from contact injection and an increase in signal including avalanche multiplication and gain of the signal produced by incoming high energy radiation. These enhanced radiation sensitive devices can be used as measuring and detection means for visible light, low energy photons and high energy ionizing particles such as electrons, x-rays, alpha particles, beta particles and gamma radiation. Particular utility of the device is disclosed for precision powder crystallography and biological identification. 13 figs.

  11. Photovoltaic radiation detector element

    DOEpatents

    Agouridis, D.C.

    1980-12-17

    A radiation detector element is formed of a body of semiconductor material, a coating on the body which forms a photovoltaic junction therewith, and a current collector consisting of narrow metallic strips, the aforesaid coating having an opening therein in the edge of which closely approaches but is spaced from the current collector strips.

  12. Semiconductor radiation detector

    DOEpatents

    Patt, Bradley E. (Sherman Oaks, CA); Iwanczyk, Jan S. (Los Angeles, CA); Tull, Carolyn R. (Orinda, CA); Vilkelis, Gintas (Westlake Village, CA)

    2002-01-01

    A semiconductor radiation detector is provided to detect x-ray and light photons. The entrance electrode is segmented by using variable doping concentrations. Further, the entrance electrode is physically segmented by inserting n+ regions between p+ regions. The p+ regions and the n+ regions are individually biased. The detector elements can be used in an array, and the p+ regions and the n+ regions can be biased by applying potential at a single point. The back side of the semiconductor radiation detector has an n+ anode for collecting created charges and a number of p+ cathodes. Biased n+ inserts can be placed between the p+ cathodes, and an internal resistor divider can be used to bias the n+ inserts as well as the p+ cathodes. A polysilicon spiral guard can be implemented surrounding the active area of the entrance electrode or surrounding an array of entrance electrodes.

  13. Handheld CZT radiation detector

    DOEpatents

    Murray, William S.; Butterfield, Kenneth B.; Baird, William

    2004-08-24

    A handheld CZT radiation detector having a CZT gamma-ray sensor, a multichannel analyzer, a fuzzy-logic component, and a display component is disclosed. The CZT gamma-ray sensor may be a coplanar grid CZT gamma-ray sensor, which provides high-quality gamma-ray analysis at a wide range of operating temperatures. The multichannel analyzer categorizes pulses produce by the CZT gamma-ray sensor into channels (discrete energy levels), resulting in pulse height data. The fuzzy-logic component analyzes the pulse height data and produces a ranked listing of radioisotopes. The fuzzy-logic component is flexible and well-suited to in-field analysis of radioisotopes. The display component may be a personal data assistant, which provides a user-friendly method of interacting with the detector. In addition, the radiation detector may be equipped with a neutron sensor to provide an enhanced mechanism of sensing radioactive materials.

  14. Semiconductor radiation detector

    DOEpatents

    Bell, Zane W. (Oak Ridge, TN); Burger, Arnold (Knoxville, TN)

    2010-03-30

    A semiconductor detector for ionizing electromagnetic radiation, neutrons, and energetic charged particles. The detecting element is comprised of a compound having the composition I-III-VI.sub.2 or II-IV-V.sub.2 where the "I" component is from column 1A or 1B of the periodic table, the "II" component is from column 2B, the "III" component is from column 3A, the "IV" component is from column 4A, the "V" component is from column 5A, and the "VI" component is from column 6A. The detecting element detects ionizing radiation by generating a signal proportional to the energy deposited in the element, and detects neutrons by virtue of the ionizing radiation emitted by one or more of the constituent materials subsequent to capture. The detector may contain more than one neutron-sensitive component.

  15. Simple dynamic electromagnetic radiation detector

    NASA Technical Reports Server (NTRS)

    Been, J. F.

    1972-01-01

    Detector monitors gamma dose rate at particular position in a radiation facility where a mixed neutron-gamma environment exists, thus determining reactor power level changes. Device also maps gamma intensity profile across a neutron-gamma beam.

  16. Solid xenon radiation detectors

    NASA Astrophysics Data System (ADS)

    Dolinski, Michelle J.

    2014-03-01

    Cryogenic liquid xenon detectors have become a popular technology in the search for rare events, such as dark matter interactions and neutrinoless double beta decay. The power of the liquid xenon detector technology is in the combination of the ionization and scintillation signals, resulting in particle discrimination and improved energy resolution over the ionization-only signal. The improved energy resolution results from a unique anti-correlation phenomenon that has not been described from first principles. Solid xenon bolometers, under development at Drexel University, are expected to have excellent counting statistics in the phonon channel, with energy resolution of 0.1% or better. This additional energy channel may offer the final piece of the puzzle in understanding liquid xenon detector energy response. Supported by a grant from the Charles E. Kaufman Foundation.

  17. Broadband optical radiation detector

    NASA Technical Reports Server (NTRS)

    Gupta, A.; Hong, S. D.; Moacanin, J. (inventors)

    1981-01-01

    A method and apparatus for detecting optical radiation by optically monitoring temperature changes in a microvolume caused by absorption of the optical radiation to be detected is described. More specifically, a thermal lens forming material is provided which has first and second opposite, substantially parallel surfaces. A reflective coating is formed on the first surface, and a radiation absorbing coating is formed on the reflective coating. Chopped, incoming optical radiation to be detected is directed to irradiate a small portion of the radiation absorbing coating. Heat generated in this small area is conducted to the lens forming material through the reflective coating, thereby raising the temperature of a small portion of the lens forming material and causing a thermal lens to be formed therein.

  18. Cadmium telluride photovoltaic radiation detector

    DOEpatents

    Agouridis, Dimitrios C. (Oak Ridge, TN); Fox, Richard J. (Oak Ridge, TN)

    1981-01-01

    A dosimetry-type radiation detector is provided which employs a polycrystalline, chlorine-compensated cadmium telluride wafer fabricated to operate as a photovoltaic current generator used as the basic detecting element. A photovoltaic junction is formed in the wafer by painting one face of the cadmium telluride wafer with an n-type semiconductive material. The opposite face of the wafer is painted with an electrically conductive material to serve as a current collector. The detector is mounted in a hermetically sealed vacuum containment. The detector is operated in a photovoltaic mode (zero bias) while DC coupled to a symmetrical differential current amplifier having a very low input impedance. The amplifier converts the current signal generated by radiation impinging upon the barrier surface face of the wafer to a voltage which is supplied to a voltmeter calibrated to read quantitatively the level of radiation incident upon the detecting wafer.

  19. Advanced Space Radiation Detector Technology Development

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D.; Wrbanek, Susan Y.; Fralick, Gustave C.

    2013-01-01

    The advanced space radiation detector development team at NASA Glenn Research Center (GRC) has the goal of developing unique, more compact radiation detectors that provide improved real-time data on space radiation. The team has performed studies of different detector designs using a variety of combinations of solid-state detectors, which allow higher sensitivity to radiation in a smaller package and operate at lower voltage than traditional detectors. Integration of multiple solid-state detectors will result in an improved detector system in comparison to existing state-of-the-art (SOA) instruments for the detection and monitoring of the space radiation field for deep space and aerospace applications.

  20. Advanced Space Radiation Detector Technology Development

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D.; Wrbanek, Susan Y.; Fralick, Gustave C.

    2013-01-01

    The advanced space radiation detector development team at the NASA Glenn Research Center (GRC) has the goal of developing unique, more compact radiation detectors that provide improved real-time data on space radiation. The team has performed studies of different detector designs using a variety of combinations of solid-state detectors, which allow higher sensitivity to radiation in a smaller package and operate at lower voltage than traditional detectors. Integration of multiple solid-state detectors will result in an improved detector system in comparison to existing state-of-the-art instruments for the detection and monitoring of the space radiation field for deep space and aerospace applications.

  1. Advanced Space Radiation Detector Technology Development

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D.; Wrbanek, Susan Y.; Fralick, Gustave C.

    2013-01-01

    The advanced space radiation detector development team at NASA Glenn Research Center (GRC) has the goal of developing unique, more compact radiation detectors that provide improved real-time data on space radiation. The team has performed studies of different detector designs using a variety of combinations of solid-state detectors, which allow higher sensitivity to radiation in a smaller package and operate at lower voltage than traditional detectors. Integration of multiple solid-state detectors will result in an improved detector system in comparison to existing state-of-the-art instruments for the detection and monitoring of the space radiation field for deep space and aerospace applications.

  2. Ionizing Radiation Detector

    DOEpatents

    Wright, Gomez W. (Nashville, TN); James, Ralph B. (Livermore, CA); Burger, Arnold (Nashville, TN); Chinn, Douglas A. (Livermore, CA)

    2003-11-18

    A CdZnTe (CZT) crystal provided with a native CdO dielectric coating to reduce surface leakage currents and thereby, improve the resolution of instruments incorporating detectors using CZT crystals is disclosed. A two step process is provided for forming the dielectric coating which includes etching the surface of a CZT crystal with a solution of the conventional bromine/methanol etch treatment, and passivating the CZT crystal surface with a solution of 10 w/o NH.sub.4 F and 10 w/o H.sub.2 O.sub.2 in water after attaching electrical contacts to the crystal surface.

  3. Flexible composite radiation detector

    DOEpatents

    Cooke, D. Wayne (Santa Fe, NM); Bennett, Bryan L. (Los Alamos, NM); Muenchausen, Ross E. (Los Alamos, NM); Wrobleski, Debra A. (Los Alamos, NM); Orler, Edward B. (Los Alamos, NM)

    2006-12-05

    A flexible composite scintillator was prepared by mixing fast, bright, dense rare-earth doped powdered oxyorthosilicate (such as LSO:Ce, LSO:Sm, and GSO:Ce) scintillator with a polymer binder. The binder is transparent to the scintillator emission. The composite is seamless and can be made large and in a wide variety of shapes. Importantly, the composite can be tailored to emit light in a spectral region that matches the optimum response of photomultipliers (about 400 nanometers) or photodiodes (about 600 nanometers), which maximizes the overall detector efficiency.

  4. Radiation detector spectrum simulator

    DOEpatents

    Wolf, M.A.; Crowell, J.M.

    1985-04-09

    A small battery operated nuclear spectrum simulator having a noise source generates pulses with a Gaussian distribution of amplitudes. A switched dc bias circuit cooperating therewith to generate several nominal amplitudes of such pulses and a spectral distribution of pulses that closely simulates the spectrum produced by a radiation source such as Americium 241.

  5. Radiation detector spectrum simulator

    DOEpatents

    Wolf, Michael A. (Los Alamos, NM); Crowell, John M. (Los Alamos, NM)

    1987-01-01

    A small battery operated nuclear spectrum simulator having a noise source nerates pulses with a Gaussian distribution of amplitudes. A switched dc bias circuit cooperating therewith generates several nominal amplitudes of such pulses and a spectral distribution of pulses that closely simulates the spectrum produced by a radiation source such as Americium 241.

  6. Advanced Radiation Detector Development

    SciTech Connect

    The University of Michigan

    1998-07-01

    Since our last progress report, the project at The University of Michigan has continued to concentrate on the development of gamma ray spectrometers fabricated from cadmium zinc telluride (CZT). This material is capable of providing energy resolution that is superior to that of scintillation detectors, while avoiding the necessity for cooling associated with germanium systems. In our past reports, we have described one approach (the coplanar grid electrode) that we have used to partially overcome some of the major limitations on charge collection that is found in samples of CZT. This approach largely eliminates the effect of hole motion in the formation of the output signal, and therefore leads to pulses that depend only on the motion of a single carrier (electrons). Since electrons move much more readily through CZT than do holes, much better energy resolution can be achieved under these conditions. In our past reports, we have described a 1 cm cube CZT spectrometer fitted with coplanar grids that achieved an energy resolution of 1.8% from the entire volume of the crystal. This still represents, to our knowledge, the best energy resolution ever demonstrated in a CZT detector of this size.

  7. Plasma Panel Based Radiation Detectors

    SciTech Connect

    Friedman, Dr. Peter S.; Varner Jr, Robert L; Ball, Robert; Beene, James R; Ben Moshe, M.; Benhammou, Yan; Chapman, J. Wehrley; Etzion, E; Ferretti, Claudio; Bentefour, E; Levin, Daniel S.; Moshe, M.; Silver, Yiftah; Weaverdyck, Curtis; Zhou, Bing

    2013-01-01

    The plasma panel sensor (PPS) is a gaseous micropattern radiation detector under current development. It has many operational and fabrication principles common to plasma display panels (PDPs). It comprises a dense matrix of small, gas plasma discharge cells within a hermetically sealed panel. As in PDPs, it uses non-reactive, intrinsically radiation-hard materials such as glass substrates, refractory metal electrodes, and mostly inert gas mixtures. We are developing these devices primarily as thin, low-mass detectors with gas gaps from a few hundred microns to a few millimeters. The PPS is a high gain, inherently digital device with the potential for fast response times, fine position resolution (< 50 m RMS) and low cost. In this paper we report here on prototype PPS experimental results in detecting betas, protons and cosmic muons, and we extrapolate on the PPS potential for applications including detection of alphas, heavy-ions at low to medium energy, thermal neutrons and X-rays.

  8. Direct detector for terahertz radiation

    DOEpatents

    Wanke, Michael C. (Albuquerque, NM); Lee, Mark (Albuquerque, NM); Shaner, Eric A. (Albuquerque, NM); Allen, S. James (Santa Barbara, CA)

    2008-09-02

    A direct detector for terahertz radiation comprises a grating-gated field-effect transistor with one or more quantum wells that provide a two-dimensional electron gas in the channel region. The grating gate can be a split-grating gate having at least one finger that can be individually biased. Biasing an individual finger of the split-grating gate to near pinch-off greatly increases the detector's resonant response magnitude over prior QW FET detectors while maintaining frequency selectivity. The split-grating-gated QW FET shows a tunable resonant plasmon response to FIR radiation that makes possible an electrically sweepable spectrometer-on-a-chip with no moving mechanical optical parts. Further, the narrow spectral response and signal-to-noise are adequate for use of the split-grating-gated QW FET in a passive, multispectral terahertz imaging system. The detector can be operated in a photoconductive or a photovoltaic mode. Other embodiments include uniform front and back gates to independently vary the carrier densities in the channel region, a thinned substrate to increase bolometric responsivity, and a resistive shunt to connect the fingers of the grating gate in parallel and provide a uniform gate-channel voltage along the length of the channel to increase the responsivity and improve the spectral resolution.

  9. 49 CFR 173.310 - Exceptions for radiation detectors.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false Exceptions for radiation detectors. 173.310 Section 173.310 ...Preparation and Packaging § 173.310 Exceptions for radiation detectors. Radiation detectors, radiation sensors, electron tube...

  10. 49 CFR 173.310 - Exceptions for radiation detectors.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Preparation and Packaging § 173.310 Exceptions for radiation detectors. Radiation detectors, radiation sensors, electron tube devices, or ionization chambers, herein referred to as “radiation detectors,” that contain only Division...

  11. 49 CFR 173.310 - Exceptions for radiation detectors.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...Preparation and Packaging § 173.310 Exceptions for radiation detectors. Radiation detectors, radiation sensors, electron tube devices, or ionization chambers, herein referred to as “radiation detectors,” that contain only Division...

  12. 49 CFR 173.310 - Exceptions for radiation detectors.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Preparation and Packaging § 173.310 Exceptions for radiation detectors. Radiation detectors, radiation sensors, electron tube devices, or ionization chambers, herein referred to as “radiation detectors,” that contain only Division...

  13. 49 CFR 173.310 - Exceptions for radiation detectors.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...Preparation and Packaging § 173.310 Exceptions for radiation detectors. Radiation detectors, radiation sensors, electron tube devices, or ionization chambers, herein referred to as “radiation detectors,” that contain only Division...

  14. Hybrid anode for semiconductor radiation detectors

    DOEpatents

    Yang, Ge; Bolotnikov, Aleksey E; Camarda, Guiseppe; Cui, Yonggang; Hossain, Anwar; Kim, Ki Hyun; James, Ralph B

    2013-11-19

    The present invention relates to a novel hybrid anode configuration for a radiation detector that effectively reduces the edge effect of surface defects on the internal electric field in compound semiconductor detectors by focusing the internal electric field of the detector and redirecting drifting carriers away from the side surfaces of the semiconductor toward the collection electrode(s).

  15. Electron gas grid semiconductor radiation detectors

    DOEpatents

    Lee, Edwin Y. (Livermore, CA); James, Ralph B. (Livermore, CA)

    2002-01-01

    An electron gas grid semiconductor radiation detector (EGGSRAD) useful for gamma-ray and x-ray spectrometers and imaging systems is described. The radiation detector employs doping of the semiconductor and variation of the semiconductor detector material to form a two-dimensional electron gas, and to allow transistor action within the detector. This radiation detector provides superior energy resolution and radiation detection sensitivity over the conventional semiconductor radiation detector and the "electron-only" semiconductor radiation detectors which utilize a grid electrode near the anode. In a first embodiment, the EGGSRAD incorporates delta-doped layers adjacent the anode which produce an internal free electron grid well to which an external grid electrode can be attached. In a second embodiment, a quantum well is formed between two of the delta-doped layers, and the quantum well forms the internal free electron gas grid to which an external grid electrode can be attached. Two other embodiments which are similar to the first and second embodiment involve a graded bandgap formed by changing the composition of the semiconductor material near the first and last of the delta-doped layers to increase or decrease the conduction band energy adjacent to the delta-doped layers.

  16. Metamaterials for Cherenkov Radiation Based Particle Detectors

    SciTech Connect

    Tyukhtin, A. V.; Schoessow, P.; Kanareykin, A.; Antipov, S.

    2009-01-22

    Measurement of Cherenkov radiation (CR) has long been a useful technique for charged particle detection and beam diagnostics. We are investigating metamaterials engineered to have refractive indices tailored to enhance properties of CR that are useful for particle detectors and that cannot be obtained using conventional media. Cherenkov radiation in dispersive media with a large refractive index differs significantly from the same effect in conventional detector media, like gases or aerogel. The radiation pattern of CR in dispersive metamaterials presents lobes at very large angles with respect to particle motion. Moreover, the frequency and particle velocity dependence of the radiated energy can differ significantly from CR in a conventional dielectric medium.

  17. Enhanced radiation detectors using luminescent materials

    DOEpatents

    Vardeny, Zeev V. (Holladay, UT); Jeglinski, Stefan A. (Durham, NC); Lane, Paul A. (Sheffield, GB)

    2001-01-01

    A radiation detecting device comprising a radiation sensing element, and a layer of luminescent material to expand the range of wavelengths over which the sensing element can efficiently detect radiation. The luminescent material being selected to absorb radiation at selected wavelengths, causing the luminescent material to luminesce, and the luminescent radiation being detected by the sensing element. Radiation sensing elements include photodiodes (singly and in arrays), CCD arrays, IR detectors and photomultiplier tubes. Luminescent materials include polymers, oligomers, copolymers and porphyrines, Luminescent layers include thin films, thicker layers, and liquid polymers.

  18. Wafer-fused semiconductor radiation detector

    DOEpatents

    Lee, Edwin Y. (Livermore, CA); James, Ralph B. (Livermore, CA)

    2002-01-01

    Wafer-fused semiconductor radiation detector useful for gamma-ray and x-ray spectrometers and imaging systems. The detector is fabricated using wafer fusion to insert an electrically conductive grid, typically comprising a metal, between two solid semiconductor pieces, one having a cathode (negative electrode) and the other having an anode (positive electrode). The wafer fused semiconductor radiation detector functions like the commonly used Frisch grid radiation detector, in which an electrically conductive grid is inserted in high vacuum between the cathode and the anode. The wafer-fused semiconductor radiation detector can be fabricated using the same or two different semiconductor materials of different sizes and of the same or different thicknesses; and it may utilize a wide range of metals, or other electrically conducting materials, to form the grid, to optimize the detector performance, without being constrained by structural dissimilarity of the individual parts. The wafer-fused detector is basically formed, for example, by etching spaced grooves across one end of one of two pieces of semiconductor materials, partially filling the grooves with a selected electrical conductor which forms a grid electrode, and then fusing the grooved end of the one semiconductor piece to an end of the other semiconductor piece with a cathode and an anode being formed on opposite ends of the semiconductor pieces.

  19. Processing circuitry for single channel radiation detector

    NASA Technical Reports Server (NTRS)

    Holland, Samuel D. (Inventor); Delaune, Paul B. (Inventor); Turner, Kathryn M. (Inventor)

    2009-01-01

    Processing circuitry is provided for a high voltage operated radiation detector. An event detector utilizes a comparator configured to produce an event signal based on a leading edge threshold value. A preferred event detector does not produce another event signal until a trailing edge threshold value is satisfied. The event signal can be utilized for counting the number of particle hits and also for controlling data collection operation for a peak detect circuit and timer. The leading edge threshold value is programmable such that it can be reprogrammed by a remote computer. A digital high voltage control is preferably operable to monitor and adjust high voltage for the detector.

  20. Synchrotron light sources and radiation detector metrology

    NASA Astrophysics Data System (ADS)

    Owens, Alan

    2012-12-01

    Synchrotron light sources are widely used in materials science, protein crystallography and biomicroscopy applications. They provide a unique stable source of high intensity photons, extending over a broad energy range from the far infrared to the ?-ray region. However, they have also proven invaluable for carrying out detailed metrology of radiation detectors by making available highly collimated and controllable monochromatized beams of synchrotron radiation. Light sources are only accessible at synchrotron research facilities and a number of specialized laboratories (for example, the Physikalisch-Technische Bundesanstalt (PTB), radiometry laboratories in Berlin, Germany) have been established specifically to be carry out photon metrology from the UV to the X-ray wavelengths using primary source standards in conjunction with primary detector standards. In this review, we discuss the use of synchrotron radiation for characterizing and calibrating X- and gamma-ray radiation detectors.

  1. Device for calibrating a radiation detector system

    DOEpatents

    Mc Fee, Matthew C. (New Ellenton, SC); Kirkham, Tim J. (Beech Island, SC); Johnson, Tippi H. (Aiken, SC)

    1994-01-01

    A device for testing a radiation detector system that includes at least two arrays of radiation detectors that are movable with respect to each other. The device includes a "shield plate" or shell, and an opposing "source plate" containing a source of ionizing radiation. Guides are attached to the outer surface of the shell for engaging the forward ends of the detectors, thereby reproducibly positioning the detectors with respect to the source and with respect to each other, thereby ensuring that a predetermined portion of the radiation emitted by the source passes through the shell and reaches the detectors. The shell is made of an hydrogenous material having approximately the same radiological attenuation characteristics as composite human tissue. The source represents a human organ such as the lungs, heart, kidneys, heart, liver, spleen, pancreas, thyroid, testes, prostate, or ovaries. The source includes a source of ionizing radiation having a long half-life and an activity that is within the range typically searched for in human subjects.

  2. Device for calibrating a radiation detector system

    DOEpatents

    McFee, M.C.; Kirkham, T.J.; Johnson, T.H.

    1994-12-27

    A device is disclosed for testing a radiation detector system that includes at least two arrays of radiation detectors that are movable with respect to each other. The device includes a ''shield plate'' or shell, and an opposing ''source plate'' containing a source of ionizing radiation. Guides are attached to the outer surface of the shell for engaging the forward ends of the detectors, thereby reproducibly positioning the detectors with respect to the source and with respect to each other, thereby ensuring that a predetermined portion of the radiation emitted by the source passes through the shell and reaches the detectors. The shell is made of an hydrogenous material having approximately the same radiological attenuation characteristics as composite human tissue. The source represents a human organ such as the lungs, heart, kidneys, liver, spleen, pancreas, thyroid, testes, prostate, or ovaries. The source includes a source of ionizing radiation having a long half-life and an activity that is within the range typically searched for in human subjects. 3 figures.

  3. Radiation and particle detector and amplifier

    NASA Technical Reports Server (NTRS)

    Schmidt, K. C. (inventor)

    1973-01-01

    A radiation or charged particle detector is described which incorporates a channel multiplier structure to amplify the detected rays or particles. The channel multiplier structure has a support multiplying element with a longitudinal slot along one side. The element supports a pair of plates positioned contiguous with the slot. The plates funnel the particles or rays to be detected into the slotted aperture and the element, thus creating an effectively wide aperture detector of the windowless type.

  4. Multiple-mode radiation detector

    SciTech Connect

    Claus, Liam D.; Derzon, Mark S.; Kay, Randolph R.; Bauer, Todd; Trotter, Douglas Chandler; Henry, Michael David

    2015-08-25

    An apparatus for detecting radiation is provided. In embodiments, at least one sensor medium is provided, of a kind that interacts with radiation to generate photons and/or charge carriers. The apparatus also includes at least one electrode arrangement configured to collect radiation-generated charge from a sensor medium that has been provided. The apparatus also includes at least one photodetector configured to produce an electrical output in response to photons generated by radiation in such a sensor medium, and an electronic circuit configured to produce an output that is jointly responsive to the collected charge and to the photodetector output. At least one such electrode arrangement, at least one such photodetector, and at least one such sensor medium are combined to form an integral unit.

  5. Low-Power Multi-Aspect Space Radiation Detector System

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D.; Wrbanek, Susan Y.; Fralick, Gustave; Freeman, Jon C.; Burkebile, Stephen P.

    2012-01-01

    The advanced space radiation detector development team at NASA Glenn Research Center (GRC) has the goal of developing unique, more compact radiation detectors that provide improved real-time data on space radiation. The team has performed studies of different detector designs using a variety of combinations of solid-state detectors, which allow higher sensitivity to radiation in a smaller package and operate at lower voltage than traditional detectors. Integration of all of these detector technologies will result in an improved detector system in comparison to existing state-of-the-art (SOA) instruments for the detection and monitoring of the deep space radiation field.

  6. Imaging radiation detector with gain

    DOEpatents

    Morris, Christopher L. (Los Alamos, NM); Idzorek, George C. (Los Alamos, NM); Atencio, Leroy G. (Espanola, NM)

    1984-01-01

    A radiation imaging device which has application in x-ray imaging. The device can be utilized in CAT scanners and other devices which require high sensitivity and low x-ray fluxes. The device utilizes cumulative multiplication of charge carriers on the anode plane and the collection of positive ion charges to image the radiation intensity on the cathode plane. Parallel and orthogonal cathode wire arrays are disclosed as well as a two-dimensional grid pattern for collecting the positive ions on the cathode.

  7. Imaging radiation detector with gain

    DOEpatents

    Morris, C.L.; Idzorek, G.C.; Atencio, L.G.

    1982-07-21

    A radiation imaging device which has application in x-ray imaging. The device can be utilized in CAT scanners and other devices which require high sensitivity and low x-ray fluxes. The device utilizes cumulative multiplication of charge carriers on the anode plane and the collection of positive ion charges to image the radiation intensity on the cathode plane. Parallel and orthogonal cathode wire arrays are disclosed as well as a two-dimensional grid pattern for collecting the positive ions on the cathode.

  8. Integrator Circuitry for Single Channel Radiation Detector

    NASA Technical Reports Server (NTRS)

    Holland, Samuel D. (Inventor); Delaune, Paul B. (Inventor); Turner, Kathryn M. (Inventor)

    2008-01-01

    Input circuitry is provided for a high voltage operated radiation detector to receive pulses from the detector having a rise time in the range of from about one nanosecond to about ten nanoseconds. An integrator circuit, which utilizes current feedback, receives the incoming charge from the radiation detector and creates voltage by integrating across a small capacitor. The integrator utilizes an amplifier which closely follows the voltage across the capacitor to produce an integrator output pulse with a peak value which may be used to determine the energy which produced the pulse. The pulse width of the output is stretched to approximately 50 to 300 nanoseconds for use by subsequent circuits which may then use amplifiers with lower slew rates.

  9. Workshop on detectors for synchrotron radiation

    SciTech Connect

    Robinson, Arthur L.

    2000-11-22

    Forefront experiments in many scientific areas for which synchrotron sources provide sufficient flux are nonetheless hindered because detectors cannot collect data fast enough, do not cover sufficiently solid angle, or do no have adequate resolution. Overall, the synchrotron facilities, each of which represents collective investments from funding agencies and user institutions ranging from many hundreds of millions to more than a billion dollars, are effectively significantly underutilized. While this chronic and growing problem plagues facilities around the world, it is particularly acute in the United States, where detector research often has to ride on the coat tails of explicitly science-oriented projects. As a first step toward moving out of this predicament, scientists from the U.S. synchrotron facilities held a national workshop in Washington, DC, on October 30-31, 2000. The Workshop on Detectors for Synchrotron Research aimed to create a national ''roadmap'' for development of synchrotron-radiation detectors.

  10. A semiconductor radiation imaging pixel detector for space radiation dosimetry.

    PubMed

    Kroupa, Martin; Bahadori, Amir; Campbell-Ricketts, Thomas; Empl, Anton; Hoang, Son Minh; Idarraga-Munoz, John; Rios, Ryan; Semones, Edward; Stoffle, Nicholas; Tlustos, Lukas; Turecek, Daniel; Pinsky, Lawrence

    2015-07-01

    Progress in the development of high-performance semiconductor radiation imaging pixel detectors based on technologies developed for use in high-energy physics applications has enabled the development of a completely new generation of compact low-power active dosimeters and area monitors for use in space radiation environments. Such detectors can provide real-time information concerning radiation exposure, along with detailed analysis of the individual particles incident on the active medium. Recent results from the deployment of detectors based on the Timepix from the CERN-based Medipix2 Collaboration on the International Space Station (ISS) are reviewed, along with a glimpse of developments to come. Preliminary results from Orion MPCV Exploration Flight Test 1 are also presented. PMID:26256630

  11. High resolution amorphous silicon radiation detectors

    DOEpatents

    Street, R.A.; Kaplan, S.N.; Perez-Mendez, V.

    1992-05-26

    A radiation detector employing amorphous Si:H cells in an array with each detector cell having at least three contiguous layers (n-type, intrinsic, p-type), positioned between two electrodes to which a bias voltage is applied. An energy conversion layer atop the silicon cells intercepts incident radiation and converts radiation energy to light energy of a wavelength to which the silicon cells are responsive. A read-out device, positioned proximate to each detector element in an array allows each such element to be interrogated independently to determine whether radiation has been detected in that cell. The energy conversion material may be a layer of luminescent material having a columnar structure. In one embodiment a column of luminescent material detects the passage therethrough of radiation to be detected and directs a light beam signal to an adjacent a-Si:H film so that detection may be confined to one or more such cells in the array. One or both electrodes may have a comb structure, and the teeth of each electrode comb may be interdigitated for capacitance reduction. The amorphous Si:H film may be replaced by an amorphous Si:Ge:H film in which up to 40 percent of the amorphous material is Ge. Two dimensional arrays may be used in X-ray imaging, CT scanning, crystallography, high energy physics beam tracking, nuclear medicine cameras and autoradiography. 18 figs.

  12. High resolution amorphous silicon radiation detectors

    DOEpatents

    Street, Robert A. (Palo Alto, CA); Kaplan, Selig N. (El Cerrito, CA); Perez-Mendez, Victor (Berkeley, CA)

    1992-01-01

    A radiation detector employing amorphous Si:H cells in an array with each detector cell having at least three contiguous layers (n type, intrinsic, p type), positioned between two electrodes to which a bias voltage is applied. An energy conversion layer atop the silicon cells intercepts incident radiation and converts radiation energy to light energy of a wavelength to which the silicon cells are responsive. A read-out device, positioned proximate to each detector element in an array allows each such element to be interrogated independently to determine whether radiation has been detected in that cell. The energy conversion material may be a layer of luminescent material having a columnar structure. In one embodiment a column of luminescent material detects the passage therethrough of radiation to be detected and directs a light beam signal to an adjacent a-Si:H film so that detection may be confined to one or more such cells in the array. One or both electrodes may have a comb structure, and the teeth of each electrode comb may be interdigitated for capacitance reduction. The amorphous Si:H film may be replaced by an amorphous Si:Ge:H film in which up to 40 percent of the amorphous material is Ge. Two dimensional arrays may be used in X-ray imaging, CT scanning, crystallography, high energy physics beam tracking, nuclear medicine cameras and autoradiography.

  13. Alpha-beta radiation detector

    DOEpatents

    Fleming, Dale M. (Richland, WA); Simmons, Kevin L. (Kennewick, WA); Froelich, Thomas J. (West Richland, WA); Carter, Gregory L. (Richland, WA)

    1998-01-01

    The invention is based in part on the discovery that a plastic housing that is lightweight is surprisingly efficient inasmuch as background signals from any gamma radiation are significantly reduced by using a plastic housing instead of a metal housing. A further aspect of the present invention is the profile of the housing as a bi-linear approximation to a parabola resulting in full optical response from any location on the scintillation material to the photomultiplier tube. A yet further aspect of the present invention is that the survey probe is resistant to magnetic fields. A yet further aspect of the present invention is the use of a snap-fit retaining bracket that overcomes the need for multiple screws.

  14. Alpha-beta radiation detector

    DOEpatents

    Fleming, D.M.; Simmons, K.L.; Froelich, T.J.; Carter, G.L.

    1998-08-18

    The invention is based in part on the discovery that a plastic housing that is lightweight is surprisingly efficient inasmuch as background signals from any gamma radiation are significantly reduced by using a plastic housing instead of a metal housing. A further aspect of the present invention is the profile of the housing as a bi-linear approximation to a parabola resulting in full optical response from any location on the scintillation material to the photomultiplier tube. A yet further aspect of the present invention is that the survey probe is resistant to magnetic fields. A yet further aspect of the present invention is the use of a snap-fit retaining bracket that overcomes the need for multiple screws. 16 figs.

  15. Electromagnetic Radiation Hardness of Diamond Detectors

    E-print Network

    T. Behnke; M. Doucet; N. Ghodbane; A. Imhof; C. Martinez; W. Zeuner

    2001-08-22

    The behavior of artificially grown CVD diamond films under intense electromagnetic radiation has been studied. The properties of irradiated diamond samples have been investigated using the method of thermally stimulated current and by studying their charge collection properties. Diamonds have been found to remain unaffected after doses of 6.8 MGy of 10 keV photons and 10 MGy of MeV-range photons. This observation makes diamond an attractive detector material for a calorimeter in the very forward region of the proposed TESLA detector.

  16. Development of a plasma panel radiation detector

    SciTech Connect

    Ball, Robert; Beene, James R; Ben Moshe, M.; Benhammou, Yan; Bensimon, B; Chapman, J. Wehrley; Etzion, E; Ferretti, Claudio; Friedman, Dr. Peter S.; Levin, Daniel S.; Silver, Yiftah; Weaverdyck, Curtis; Wetzel, R.; Zhou, Bing; Anderson, T; McKinny, K; Bentefour, E

    2014-11-01

    This article reports on the development and experimental results of commercial plasma display panels adapted for their potential use as micropattern gas radiation detectors. The plasma panel sensor (PPS) design and materials include glass substrates, metal electrodes and inert gas mixtures which provide a physically robust, hermetically sealed device. Plasma display panels used as detectors were tested with cosmic ray muons, beta rays and gamma rays, protons, and thermal neutrons. The results demonstrated rise times and time resolution of a few nanoseconds, as well as sub-millimeter spatial resolution compatible with the pixel pitch.

  17. Surface wave chemical detector using optical radiation

    DOEpatents

    Thundat, Thomas G.; Warmack, Robert J.

    2007-07-17

    A surface wave chemical detector comprising at least one surface wave substrate, each of said substrates having a surface wave and at least one measurable surface wave parameter; means for exposing said surface wave substrate to an unknown sample of at least one chemical to be analyzed, said substrate adsorbing said at least one chemical to be sensed if present in said sample; a source of radiation for radiating said surface wave substrate with different wavelengths of said radiation, said surface wave parameter being changed by said adsorbing; and means for recording signals representative of said surface wave parameter of each of said surface wave substrates responsive to said radiation of said different wavelengths, measurable changes of said parameter due to adsorbing said chemical defining a unique signature of a detected chemical.

  18. Plasma panel-based radiation detectors

    E-print Network

    Peter Friedman; Robert Ball; James Beene; Yan Benhammou; Meny Ben-Moshe; Hassan Bentefour; J. W. Chapman; Erez Etzion; Claudio Ferretti; Daniel Levin; Yiftah Silver; Robert Varner; Curtis Weaverdyck; Bing Zhou

    2013-05-10

    The plasma panel sensor (PPS) is a gaseous micropattern radiation detector under current development. It has many operational and fabrication principles common to plasma display panels. It comprises a dense matrix of small, gas plasma discharge cells within a hermetically sealed panel. As in plasma display panels, it uses nonreactive, intrinsically radiation-hard materials such as glass substrates, refractory metal electrodes, and mostly inert gas mixtures. We are developing these devices primarily as thin, low-mass detectors with gas gaps from a few hundred microns to a few millimeters. The PPS is a high gain, inherently digital device with the potential for fast response times, fine position resolution (<50-mm RMS) and low cost. In this paper, we report on prototype PPS experimental results in detecting betas, protons, and cosmic muons, and we extrapolate on the PPS potential for applications including the detection of alphas, heavy ions at low-to-medium energy, thermal neutrons, and X-rays.

  19. Radiation response issues for infrared detectors

    NASA Technical Reports Server (NTRS)

    Kalma, Arne H.

    1990-01-01

    Researchers describe the most important radiation response issues for infrared detectors. In general, the two key degradation mechanisms in infrared detectors are the noise produced by exposure to a flux of ionizing particles (e.g.; trapped electronics and protons, debris gammas and electrons, radioactive decay of neutron-activated materials) and permanent damage produced by exposure to total dose. Total-dose-induced damage is most often the result of charge trapping in insulators or at interfaces. Exposure to short pulses of ionization (e.g.; prompt x rays or gammas, delayed gammas) will cause detector upset. However, this upset is not important to a sensor unless the recovery time is too long. A few detector technologies are vulnerable to neutron-induced displacement damage, but fortunately most are not. Researchers compare the responses of the new technologies with those of the mainstream technologies of PV HgCdTe and IBC Si:As. One important reason for this comparison is to note where some of the newer technologies have the potential to provide significantly improved radiation hardness compared with that of the mainstream technologies, and thus to provide greater motivation for the pursuit of these technologies.

  20. Nano structural anodes for radiation detectors

    DOEpatents

    Cordaro, Joseph V.; Serkiz, Steven M.; McWhorter, Christopher S.; Sexton, Lindsay T.; Retterer, Scott T.

    2015-07-07

    Anodes for proportional radiation counters and a process of making the anodes is provided. The nano-sized anodes when present within an anode array provide: significantly higher detection efficiencies due to the inherently higher electric field, are amenable to miniaturization, have low power requirements, and exhibit a small electromagnetic field signal. The nano-sized anodes with the incorporation of neutron absorbing elements (e.g., .sup.10B) allow the use of neutron detectors that do not use .sup.3He.

  1. A new transition radiation detector for cosmic ray nuclei

    NASA Technical Reports Server (NTRS)

    Lheureux, J.; Meyer, P.; Muller, D.; Swordy, S.

    1981-01-01

    Test measurements on materials for transition radiation detectors at a low Lorentz factor are reported. The materials will be based on board Spacelab-2 for determining the composition and energy spectra of nuclear cosmic rays in the 1 TeV/nucleon range. The transition radiation detectors consist of a sandwich of radiator-photon detector combinations. The radiators emit X-rays and are composed of polyolefin fibers used with Xe filled multiwired proportional chamber (MWPC) detectors capable of detecting particle Lorentz factors of several hundred. The sizing of the detectors is outlined, noting the requirement of a thickness which provides a maximum ratio of transition radiation to total signal in the chambers. The fiber radiator-MWPC responses were tested at Fermilab and in an electron cyclotron. An increase in transition radiation detection was found as a square power law of Z, and the use of six radiator-MWPC on board the Spacelab-2 is outlined.

  2. Radiation detector having a multiplicity of individual detecting elements

    DOEpatents

    Whetten, Nathan R. (Burnt Hills, NY); Kelley, John E. (Albany, NY)

    1985-01-01

    A radiation detector has a plurality of detector collection element arrays immersed in a radiation-to-electron conversion medium. Each array contains a multiplicity of coplanar detector elements radially disposed with respect to one of a plurality of positions which at least one radiation source can assume. Each detector collector array is utilized only when a source is operative at the associated source position, negating the necessity for a multi-element detector to be moved with respect to an object to be examined. A novel housing provides the required containment of a high-pressure gas conversion medium.

  3. Radiation detector system having heat pipe based cooling

    DOEpatents

    Iwanczyk, Jan S.; Saveliev, Valeri D.; Barkan, Shaul

    2006-10-31

    A radiation detector system having a heat pipe based cooling. The radiation detector system includes a radiation detector thermally coupled to a thermo electric cooler (TEC). The TEC cools down the radiation detector, whereby heat is generated by the TEC. A heat removal device dissipates the heat generated by the TEC to surrounding environment. A heat pipe has a first end thermally coupled to the TEC to receive the heat generated by the TEC, and a second end thermally coupled to the heat removal device. The heat pipe transfers the heat generated by the TEC from the first end to the second end to be removed by the heat removal device.

  4. Ruggedization of CdZnTe detectors and detector assemblies for radiation detection applications

    NASA Astrophysics Data System (ADS)

    Lu, P. H.; Gomolchuk, P.; Chen, H.; Beitz, D.; Grosser, A. W.

    2015-06-01

    This paper described improvements in the ruggedization of CdZnTe detectors and detector assemblies for use in radiation detection applications. Research included experimenting with various conductive and underfill adhesive material systems suitable for CZT substrates. A detector design with encapsulation patterning was developed to protect detector surfaces and to control spacing between CZT anode and PCB carrier. Robustness of bare detectors was evaluated through temperature cycling and metallization shear testing. Attachment processes using well-chosen adhesives and PCB carrier materials were optimized to improve reliability of detector assemblies, resulted in Improved Attachment Detector Assembly. These detector assemblies were subjected to aggressive temperature cycling, and varying levels of drop/shock and vibration, in accordance with modified JEDEC, ANSI and FedEx testing standards, to assess their ruggedness. Further enhanced detector assembly ruggedization methods were investigated involving adhesive conformal coating, potting and dam filling on detector assemblies, which resulted in the Enhanced Ruggedization Detector Assembly. Large numbers of CZT detectors and detector assemblies with 5 mm and 15 mm thick, over 200 in total, were tested. Their performance was evaluated by exposure to various radioactive sources using comprehensive predefined detector specifications and testing protocols. Detector assemblies from improved attachment and enhanced ruggedization showed stable performances during the harsh environmental condition tests. In conclusion, significant progress has been made in improving the reliability and enhancing the ruggedness of CZT detector assemblies for radiation detection applications deployed in operational environments.

  5. Space Radiation Detector with Spherical Geometry

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D. (Inventor); Fralick, Gustave C. (Inventor); Wrbanek, Susan Y. (Inventor)

    2011-01-01

    A particle detector is provided, the particle detector including a spherical Cherenkov detector, and at least one pair of detector stacks. In an embodiment of the invention, the Cherenkov detector includes a sphere of ultraviolet transparent material, coated by an ultraviolet reflecting material that has at least one open port. The Cherenkov detector further includes at least one photodetector configured to detect ultraviolet light emitted from a particle within the sphere. In an embodiment of the invention, each detector stack includes one or more detectors configured to detect a particle traversing the sphere.

  6. Space Radiation Detector with Spherical Geometry

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D. (Inventor); Fralick, Gustave C. (Inventor); Wrbanek, Susan Y. (Inventor)

    2012-01-01

    A particle detector is provided, the particle detector including a spherical Cherenkov detector, and at least one pair of detector stacks. In an embodiment of the invention, the Cherenkov detector includes a sphere of ultraviolet transparent material, coated by an ultraviolet reflecting material that has at least one open port. The Cherenkov detector further includes at least one photodetector configured to detect ultraviolet light emitted from a particle within the sphere. In an embodiment of the invention, each detector stack includes one or more detectors configured to detect a particle traversing the sphere.

  7. Pyroelectric detector development for the Radiation Measurement system

    NASA Technical Reports Server (NTRS)

    Hubbard, G. S.; Mcmurray, Robert E., Jr.; Hanel, R. P.; Dominguez, D. E.; Valero, F. P. J.; Baumann, Hilary; Hansen, W. L.; Haller, E. E.

    1993-01-01

    A new class of high detectivity pyroelectric detectors developed for optimization of the radiation measurement system within the framework of the Atmospheric Radiation Measurement program is described. These devices are intended to provide detectivities of up to about 10 exp 11 cm Hz exp 0.5/W with cooling to about 100 K required for the detector focal plane.

  8. 49 CFR 173.310 - Exceptions for radiation detectors.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... equivalent level of protection. (d) Emergency response information accompanying each shipment and available from each emergency response telephone number for radiation detectors must identify those receptacles... 49 Transportation 2 2010-10-01 2010-10-01 false Exceptions for radiation detectors....

  9. 49 CFR 173.310 - Exceptions for radiation detectors.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... equivalent level of protection. (d) Emergency response information accompanying each shipment and available from each emergency response telephone number for radiation detectors must identify those receptacles... 49 Transportation 2 2013-10-01 2013-10-01 false Exceptions for radiation detectors....

  10. 49 CFR 173.310 - Exceptions for radiation detectors.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... equivalent level of protection. (d) Emergency response information accompanying each shipment and available from each emergency response telephone number for radiation detectors must identify those receptacles... 49 Transportation 2 2012-10-01 2012-10-01 false Exceptions for radiation detectors....

  11. 49 CFR 173.310 - Exceptions for radiation detectors.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... equivalent level of protection. (d) Emergency response information accompanying each shipment and available from each emergency response telephone number for radiation detectors must identify those receptacles... 49 Transportation 2 2011-10-01 2011-10-01 false Exceptions for radiation detectors....

  12. 49 CFR 173.310 - Exceptions for radiation detectors.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... equivalent level of protection. (d) Emergency response information accompanying each shipment and available from each emergency response telephone number for radiation detectors must identify those receptacles... 49 Transportation 2 2014-10-01 2014-10-01 false Exceptions for radiation detectors....

  13. Real-time self-networking radiation detector apparatus

    DOEpatents

    Kaplan, Edward (Stony Brook, NY); Lemley, James (Miller Place, NY); Tsang, Thomas Y. (Holbrook, NY); Milian, Laurence W. (East Patchogue, NY)

    2007-06-12

    The present invention is for a radiation detector apparatus for detecting radiation sources present in cargo shipments. The invention includes the features of integrating a bubble detector sensitive to neutrons and a GPS system into a miniaturized package that can wirelessly signal the presence of radioactive material in shipping containers. The bubble density would be read out if such indicated a harmful source.

  14. Progress in the Development of Plasma Panel Radiation Detectors

    E-print Network

    Robert Ball; James R. Beene; Yan Benhammou; Meny Ben Moshe; J. Wehrley Chapman; Tiesheng Dai; Erez Etzion; Peter S. Friedman; Daniel S. Levin; Yiftah Silver; Guy Sherman; Robert L. Varner Jr.; Curtis Weaverdyck; Steve White; J. Yu; Bing Zhou

    2010-12-30

    Plasma Display Panels (PDP), the underlying engine of panel plasma television displays, are being investigated for their utility as radiation detectors called Plasma Panel Sensors (PPS). The PPS a novel variant of a micropattern radiation detector, is intended to be a fast, high resolution detector comprised of an array of plasma discharge cells operating in a hermetically sealed gas mixture. We report on the PPS development effort, including recent laboratory measurements.

  15. Wire chamber radiation detector with discharge control

    DOEpatents

    Perez-Mendez, Victor (Berkeley, CA); Mulera, Terrence A. (Berkeley, CA)

    1984-01-01

    A wire chamber radiation detector (11) has spaced apart parallel electrodes (16) and grids (17, 18, 19) defining an ignition region (21) in which charged particles (12) or other ionizing radiations initiate brief localized avalanche discharges (93) and defining an adjacent memory region (22) in which sustained glow discharges (94) are initiated by the primary discharges (93). Conductors (29, 32) of the grids (18, 19) at each side of the memory section (22) extend in orthogonal directions enabling readout of the X-Y coordinates of locations at which charged particles (12) were detected by sequentially transmitting pulses to the conductors (29) of one grid (18) while detecting transmissions of the pulses to the orthogonal conductors (36) of the other grid (19) through glow discharges (94). One of the grids (19) bounding the memory region (22) is defined by an array of conductive elements (32) each of which is connected to the associated readout conductor (36) through a separate resistance (37). The wire chamber (11) avoids ambiguities and imprecisions in the readout of coordinates when large numbers of simultaneous or near simultaneous charged particles (12) have been detected. Down time between detection periods and the generation of radio frequency noise are also reduced.

  16. Radiation Effect On Gas Electron Multiplier Detector Performance

    SciTech Connect

    Park, Kwang June; Baldeloma, Edwin; Park, Seongtae; White, Andrew P.; Yu, Jaehoon

    2011-06-01

    Gas Electron Multiplier (GEM) detector is a gas device with high gain and high efficiency. These detectors use chemically perforated 65 {mu}m thick copper clad Kapton polyimide foils. Given its potential for detecting X-rays and other radiations, GEM detectors may be used in an environment with high radioactivity. The Kapton foils manufacturer, Du Pont Inc., claims that the foils are radioactive resistant. To verify whether the GEM detector performance is affected by the exposure to radiation, several GEM foils were irradiated to a {sup 60}Co source at the gamma-ray irradiation facility at Sterigenics, Tustin, CA. Four sets of GEM foils were exposed to the level of 10 kGy, 100 kGy, 1,000 kGy and 10,000 kGy. The output signal from the GEM detectors with irradiated GEM foils were measured and compared to the detector with no irradiation. We observed that the shapes of the peaks from 5.9 KeV {sup 55}Fe X-ray were distorted and that the detector gain increased compared to that of the un-irradiated detector. In particular, the detector with 10,000 kGy irradiation appeared to have the biggest peak distortion and increased gain. It was also found from that additional electrons from radiation-induced free radicals in the Kapton film contribute to output signal of the irradiated GEM detectors. Further studies are needed to explain the mechanism of these detector performance changes.

  17. Radiation Effect On Gas Electron Multiplier Detector Performance

    NASA Astrophysics Data System (ADS)

    Park, Kwang June; Baldeloma, Edwin; Park, Seongtae; White, Andrew P.; Yu, Jaehoon

    2011-06-01

    Gas Electron Multiplier (GEM) detector is a gas device with high gain and high efficiency. These detectors use chemically perforated 65 ?m thick copper clad Kapton polyimide foils. Given its potential for detecting X-rays and other radiations, GEM detectors may be used in an environment with high radioactivity. The Kapton foils manufacturer, Du Pont Inc., claims that the foils are radioactive resistant. To verify whether the GEM detector performance is affected by the exposure to radiation, several GEM foils were irradiated to a 60Co source at the gamma-ray irradiation facility at Sterigenics, Tustin, CA. Four sets of GEM foils were exposed to the level of 10 kGy, 100 kGy, 1,000 kGy and 10,000 kGy. The output signal from the GEM detectors with irradiated GEM foils were measured and compared to the detector with no irradiation. We observed that the shapes of the peaks from 5.9 KeV 55Fe X-ray were distorted and that the detector gain increased compared to that of the un-irradiated detector. In particular, the detector with 10,000 kGy irradiation appeared to have the biggest peak distortion and increased gain. It was also found from that additional electrons from radiation-induced free radicals in the Kapton film contribute to output signal of the irradiated GEM detectors. Further studies are needed to explain the mechanism of these detector performance changes.

  18. Large dynamic range radiation detector and methods thereof

    DOEpatents

    Marrs, Roscoe E. (Livermore, CA); Madden, Norman W. (Sparks, NV)

    2012-02-14

    According to one embodiment, a radiation detector comprises a scintillator and a photodiode optically coupled to the scintillator. The radiation detector also includes a bias voltage source electrically coupled to the photodiode, a first detector operatively electrically coupled to the photodiode for generating a signal indicative of a level of a charge at an output of the photodiode, and a second detector operatively electrically coupled to the bias voltage source for generating a signal indicative of an amount of current flowing through the photodiode.

  19. Heat Transfer Issues in Thin-Film Thermal Radiation Detectors

    NASA Technical Reports Server (NTRS)

    Barry, Mamadou Y.

    1999-01-01

    The Thermal Radiation Group at Virginia Polytechnic Institute and State University has been working closely with scientists and engineers at NASA's Langley Research Center to develop accurate analytical and numerical models suitable for designing next generation thin-film thermal radiation detectors for earth radiation budget measurement applications. The current study provides an analytical model of the notional thermal radiation detector that takes into account thermal transport phenomena, such as the contact resistance between the layers of the detector, and is suitable for use in parameter estimation. It was found that the responsivity of the detector can increase significantly due to the presence of contact resistance between the layers of the detector. Also presented is the effect of doping the thermal impedance layer of the detector with conducting particles in order to electrically link the two junctions of the detector. It was found that the responsivity and the time response of the doped detector decrease significantly in this case. The corresponding decrease of the electrical resistance of the doped thermal impedance layer is not sufficient to significantly improve the electrical performance of the detector. Finally, the "roughness effect" is shown to be unable to explain the decrease in the thermal conductivity often reported for thin-film layers.

  20. Effects of ionizing radiation on cryogenic infrared detectors

    NASA Technical Reports Server (NTRS)

    Moseley, S. H.; Silverberg, R. F.; Lakew, B.

    1989-01-01

    The Diffuse Infrared Background Experiment (DIRBE) is one of three experiments to be carried aboard the Cosmic Background Explorer (COBE) satellite scheduled to be launched by NASA on a Delta rocket in 1989. The DIRBE is a cryogenic absolute photometer operating in a liquid helium dewar at 1.5 K. Photometric stability is a principal requirement for achieving the scientific objectives of this experiment. The Infrared Astronomy Satellite (IRAS), launched in 1983, which used detectors similar to those in DIRBE, revealed substantial changes in detector responsivity following exposure to ionizing radiation encountered on passage through the South Atlantic Anomaly (SAA). Since the COBE will use the same 900 Km sun-synchronous orbit as IRAS, ionizing radiation-induced performance changes in the detectors were a major concern. Here, ionizing radiation tests carried out on all the DIRBE photodetectors are reported. Responsivity changes following exposure to gamma rays, protons, and alpha particle are discussed. The detector performance was monitored following a simulated entire mission life dose. In addition, the response of the detectors to individual particle interactions was measured. The InSb photovoltaic detectors and the Blocked Impurity Band (BIB) detectors revealed no significant change in responsivity following radiation exposure. The Ge:Ga detectors show large effects which were greatly reduced by proper thermal annealing.

  1. Studies of exotic nuclei with advanced radiation detectors

    NASA Astrophysics Data System (ADS)

    Podolyák, Zsolt

    2014-02-01

    Contemporary key nuclear physics questions are introduced. The role of radiation detection in the study of exotic nuclei is illustrated with examples related to NuSTAR at the FAIR facility. The discussed detection systems include: Si-tracker for light charged particle detection, the AGATA gamma-ray tracking detector, diamond detectors for heavy ion measurements, the AIDA implantation and decay detector, and the LaBr3(Ce) fast-timing array. Due to technology transfer, applications related to radiation physics are expected to benefit from these developments.

  2. Proton-induced radiation damage in germanium detectors

    SciTech Connect

    Bruckner, J.; Korfer, M.; Wanke, H. , Mainz ); Schroeder, A.N.F. ); Figes, D.; Dragovitsch, P. ); Englert, P.A.J. ); Starr, R.; Trombka, J.I. . Goddard Space Flight Center); Taylor, I. ); Drake, D.M.; Shunk, E.R. )

    1991-04-01

    High-purity germanium (HPGe) detectors will be used in future space missions for gamma-ray measurements and will be subject to interactions with energetic particles. To simulate this process several large-volume n-type HPGe detectors were incrementally exposed to a particle fluence of up to 10{sub 8} protons cm{sup {minus}2} (proton energy: 1.5 GeV) at different operating temperatures (90 to 120 K) to induce radiation damage. Basic scientific as well as engineering data on detector performance were collected. During the incremental irradiation, the peak shape produced by the detectors showed a significant change from a Gaussian shape to a broad complex structure. After the irradiation all detectors were thoroughly characterized by measuring many parameters. To remove the accumulated radiation damage the detectors were stepwise annealed at temperatures T {le} 110{degrees}C while staying specially designed cryostats. This paper shows that n-type HPGe detectors can be used in charged particles environments as high-energy resolution devices until a certain level of radiation damage is accumulated and that the damage can be removed at moderate annealing temperatures and the detector returned to operating condition.

  3. Development of position sensitive radiation detectors using gas electron multipliers.

    PubMed

    Park, Seongtae; Hahn, Chang Hie

    2009-01-01

    Gas electron multipliers (GEM) were introduced to develop a radiation detector which is applicable to medical imaging or luggage inspection systems at the airport or harbor. Two GEM foils were used in the amplifier, and an Ar/CO(2) mixed gas was inserted into the chamber at a mixing ratio of Ar:CO(2)=80:20. A two-dimensional X-ray image was taken with a 64-channel GEM detector from an Fe-55 radiation source. We also constructed a 256-channel GEM detector in which 4 charge sensitive preamplifiers were used in a daisy chain. With linear array type readout electrodes, we were able to realize a position sensitive radiation detector. PMID:19282195

  4. SIRAD e Personal radiation detectors Hani Alnawaf c

    E-print Network

    Yu, Peter K.N.

    SIRAD e Personal radiation detectors Hani Alnawaf c , Martin J. Butson a,b,c,*, Peter K.N. Yu found. When analysed with a common computer desktop scanner, the optical density response of the film;Cheung et al., 2002, 2004, 2006a, b). When measuring low-level personal radiation, devices

  5. Nuclear radiation-warning detector that measures impedance

    DOEpatents

    Savignac, Noel Felix; Gomez, Leo S; Yelton, William Graham; Robinson, Alex; Limmer, Steven

    2013-06-04

    This invention is a nuclear radiation-warning detector that measures impedance of silver-silver halide on an interdigitated electrode to detect light or radiation comprised of alpha particles, beta particles, gamma rays, X rays, and/or neutrons. The detector is comprised of an interdigitated electrode covered by a layer of silver halide. After exposure to alpha particles, beta particles, X rays, gamma rays, neutron radiation, or light, the silver halide is reduced to silver in the presence of a reducing solution. The change from the high electrical resistance (impedance) of silver halide to the low resistance of silver provides the radiation warning that detected radiation levels exceed a predetermined radiation dose threshold.

  6. Recent progress in the development of transition radiation detectors

    NASA Technical Reports Server (NTRS)

    Cherry, M. L.; Hartmann, G.; Prince, T.; Mueller, D.

    1978-01-01

    Transition-radiation detectors have been used in several recent cosmic-ray experiments for particle identification at energies E/mc-squared of at least about 1000. In order to optimize the design of such detectors and to use them for energy measurements over a broad energy range, it is necessary to study the details of the transition-radiation process. Experimental results are presented which test the theoretical predictions more precisely and at higher energies than in previous experiments. The dependence of the interference pattern in the frequency spectrum on the radiator dimensions is studied, and the total transition-radiation yield generated by electrons in various radiators is measured over a very wide energy range, from 5 to 300 GeV. The significance of the individual experimental parameters in the design of transition radiation detectors is reviewed, and the characteristics of transition-radiation detectors capable of measuring particle energies over the range E/mc-squared from about 300 to 100,000 are discussed.

  7. Radiation-hard semiconductor detectors for SuperLHC

    NASA Astrophysics Data System (ADS)

    Bruzzi, M.; Adey, J.; Al-Ajili, A.; Alexandrov, P.; Alfieri, G.; Allport, P. P.; Andreazza, A.; Artuso, M.; Assouak, S.; Avset, B. S.; Barabash, L.; Baranova, E.; Barcz, A.; Basile, A.; Bates, R.; Belova, N.; Biagi, S. F.; Bilei, G. M.; Bisello, D.; Blue, A.; Blumenau, A.; Boisvert, V.; Bolla, G.; Bondarenko, G.; Borchi, E.; Borrello, L.; Bortoletto, D.; Boscardin, M.; Bosisio, L.; Bowcock, T. J. V.; Brodbeck, T. J.; Broz, J.; Brukhanov, A.; Brzozowski, A.; Buda, M.; Buhmann, P.; Buttar, C.; Campabadal, F.; Campbell, D.; Candelori, A.; Casse, G.; Cavallini, A.; Chilingarov, A.; Chren, D.; Cindro, V.; Citterio, M.; Collins, P.; Coluccia, R.; Contarato, D.; Coutinho, J.; Creanza, D.; Cunningham, W.; Cvetkov, V.; Dalla Betta, G.-F.; Davies, G.; Dawson, I.; de Boer, W.; De Palma, M.; Demina, R.; Dervan, P.; Dierlamm, A.; Dittongo, S.; Dobrzanski, L.; Dolezal, Z.; Dolgolenko, A.; Eberlein, T.; Eremin, V.; Fall, C.; Fasolo, F.; Ferbel, T.; Fizzotti, F.; Fleta, C.; Focardi, E.; Forton, E.; Franchenko, S.; Fretwurst, E.; Gamaz, F.; Garcia, C.; Garcia-Navarro, J. E.; Gaubas, E.; Genest, M.-H.; Gill, K. A.; Giolo, K.; Glaser, M.; Goessling, C.; Golovine, V.; González Sevilla, S.; Gorelov, I.; Goss, J.; Gouldwell, A.; Grégoire, G.; Gregori, P.; Grigoriev, E.; Grigson, C.; Grillo, A.; Groza, A.; Guskov, J.; Haddad, L.; Härkönen, J.; Harding, R.; Hauler, F.; Hayama, S.; Hoeferkamp, M.; Hönniger, F.; Horazdovsky, T.; Horisberger, R.; Horn, M.; Houdayer, A.; Hourahine, B.; Hruban, A.; Hughes, G.; Ilyashenko, I.; Irmscher, K.; Ivanov, A.; Jarasiunas, K.; Jin, T.; Jones, B. K.; Jones, R.; Joram, C.; Jungermann, L.; Kalinina, E.; Kaminski, P.; Karpenko, A.; Karpov, A.; Kazlauskiene, V.; Kazukauskas, V.; Khivrich, V.; Khomenkov, V.; Kierstead, J.; Klaiber-Lodewigs, J.; Kleverman, M.; Klingenberg, R.; Kodys, P.; Kohout, Z.; Korjenevski, S.; Kowalik, A.; Kozlowski, R.; Kozodaev, M.; Kramberger, G.; Krasel, O.; Kuznetsov, A.; Kwan, S.; Lagomarsino, S.; Lari, T.; Lassila-Perini, K.; Lastovetsky, V.; Latino, G.; Latushkin, S.; Lazanu, S.; Lazanu, I.; Lebel, C.; Leinonen, K.; Leroy, C.; Li, Z.; Lindström, G.; Lindstrom, L.; Linhart, V.; Litovchenko, A.; Litovchenko, P.; Litvinov, V.; Lo Giudice, A.; Lozano, M.; Luczynski, Z.; Luukka, P.; Macchiolo, A.; Mainwood, A.; Makarenko, L. F.; Mandi?, I.; Manfredotti, C.; Marti i Garcia, S.; Marunko, S.; Mathieson, K.; Mozzanti, A.; Melone, J.; Menichelli, D.; Meroni, C.; Messineo, A.; Miglio, S.; Mikuž, M.; Miyamoto, J.; Moll, M.; Monakhov, E.; Moscatelli, F.; Murin, L.; Nava, F.; Naoumov, D.; Nossarzewska-Orlowska, E.; Nummela, S.; Nysten, J.; Olivero, P.; Oshea, V.; Palviainen, T.; Paolini, C.; Parkes, C.; Passeri, D.; Pein, U.; Pellegrini, G.; Perera, L.; Petasecca, M.; Piatkowski, B.; Piemonte, C.; Pignatel, G. U.; Pinho, N.; Pintilie, I.; Pintilie, L.; Polivtsev, L.; Polozov, P.; Popa, A. I.; Popule, J.; Pospisil, S.; Pucker, G.; Radicci, V.; Rafí, J. M.; Ragusa, F.; Rahman, M.; Rando, R.; Roeder, R.; Rohe, T.; Ronchin, S.; Rott, C.; Roy, P.; Roy, A.; Ruzin, A.; Ryazanov, A.; Sadrozinski, H. F. W.; Sakalauskas, S.; Scaringella, M.; Schiavulli, L.; Schnetzer, S.; Schumm, B.; Sciortino, S.; Scorzoni, A.; Segneri, G.; Seidel, S.; Seiden, A.; Sellberg, G.; Sellin, P.; Sentenac, D.; Shipsey, I.; Sicho, P.; Sloan, T.; Solar, M.; Son, S.; Sopko, B.; Spencer, N.; Stahl, J.; Stavitski, I.; Stolze, D.; Stone, R.; Storasta, J.; Strokan, N.; Strupinski, W.; Sudzius, M.; Surma, B.; Suuronen, J.; Suvorov, A.; Svensson, B. G.; Tipton, P.; Tomasek, M.; Troncon, C.; Tsvetkov, A.; Tuominen, E.; Tuovinen, E.; Tuuva, T.; Tylchin, M.; Uebersee, H.; Uher, J.; Ullán, M.; Vaitkus, J. V.; Vanni, P.; Velthuis, J.; Verzellesi, G.; Verbitskaya, E.; Vrba, V.; Wagner, G.; Wilhelm, I.; Worm, S.; Wright, V.; Wunstorf, R.; Zabierowski, P.; Zaluzhny, A.; Zavrtanik, M.; Zen, M.; Zhukov, V.; Zorzi, N.

    2005-04-01

    An option of increasing the luminosity of the Large Hadron Collider (LHC) at CERN to 10 35 cm -2 s -1 has been envisaged to extend the physics reach of the machine. An efficient tracking down to a few centimetres from the interaction point will be required to exploit the physics potential of the upgraded LHC. As a consequence, the semiconductor detectors close to the interaction region will receive severe doses of fast hadron irradiation and the inner tracker detectors will need to survive fast hadron fluences of up to above 10 16 cm -2. The CERN-RD50 project "Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders" has been established in 2002 to explore detector materials and technologies that will allow to operate devices up to, or beyond, this limit. The strategies followed by RD50 to enhance the radiation tolerance include the development of new or defect engineered detector materials (SiC, GaN, Czochralski and epitaxial silicon, oxygen enriched Float Zone silicon), the improvement of present detector designs and the understanding of the microscopic defects causing the degradation of the irradiated detectors. The latest advancements within the RD50 collaboration on radiation hard semiconductor detectors will be reviewed and discussed in this work.

  8. Fabrication of mercuric iodide radiation detectors

    NASA Astrophysics Data System (ADS)

    van den Berg, Lodewijk; Vigil, Ron D.

    2001-02-01

    The technologies developed at CTC to synthesize and purify mercuric iodide and to grow single crystals have made it possible to routinely produce detectors, which find applications in hand-held instruments operating at ambient temperatures. The dimensions of the detectors are specified, depending on the application, by a combination of sensitivity, spectral resolution and instrument dimensions. A short description will be given of the methods used to prepare the material and grow the crystals, of the cutting and shaping of the detector bodies and of the surface preparation and contact application, including the coating with parylene. Additional methods of encapsulation are used to protect the detectors against mechanical damage and to reduce the microphonic noise. As a result modular units are produced which are very rugged and can be used in instruments of different designs. The testing of the detectors follows the consecutive steps in the fabrication, and data will be presented to show that generally the performance improves as a result of the procedures used by us. Since the modular approach reduces the electronic noise levels processed by the preamplifier it is possible to use long shaping times up to 50 ?s which optimizes the spectral resolution.

  9. Radiation hardness of three-dimensional polycrystalline diamond detectors

    SciTech Connect

    Lagomarsino, Stefano Sciortino, Silvio; Bellini, Marco; Corsi, Chiara; Cindro, Vladimir; Kanxheri, Keida; Servoli, Leonello; Morozzi, Arianna; Passeri, Daniele; Schmidt, Christian J.

    2015-05-11

    The three-dimensional concept in particle detection is based on the fabrication of columnar electrodes perpendicular to the surface of a solid state radiation sensor. It permits to improve the radiation resistance characteristics of a material by lowering the necessary bias voltage and shortening the charge carrier path inside the material. If applied to a long-recognized exceptionally radiation-hard material like diamond, this concept promises to pave the way to the realization of detectors of unprecedented performances. We fabricated conventional and three-dimensional polycrystalline diamond detectors, and tested them before and after neutron damage up to 1.2 ×10{sup 16?}cm{sup ?2}, 1?MeV-equivalent neutron fluence. We found that the signal collected by the three-dimensional detectors is up to three times higher than that of the conventional planar ones, at the highest neutron damage ever experimented.

  10. Three-axis asymmetric radiation detector system

    DOEpatents

    Martini, Mario Pierangelo (Oak Ridge, TN); Gedcke, Dale A. (Oak Ridge, TN); Raudorf, Thomas W. (Oak Ridge, TN); Sangsingkeow, Pat (Knoxville, TN)

    2000-01-01

    A three-axis radiation detection system whose inner and outer electrodes are shaped and positioned so that the shortest path between any point on the inner electrode and the outer electrode is a different length whereby the rise time of a pulse derived from a detected radiation event can uniquely define the azimuthal and radial position of that event, and the outer electrode is divided into a plurality of segments in the longitudinal axial direction for locating the axial location of a radiation detection event occurring in the diode.

  11. The Dielectric Bolometer, A New Type of Thermal Radiation Detector

    NASA Technical Reports Server (NTRS)

    Hanel, R. A.

    1960-01-01

    Thermal detectors for the infrared, such as thermocouples and bolometers, are limited in their ultimate sensitivity predominantly by Johnson noise rather than temperature noise. Low noise figures are hard to achieve since Johnson noise preponderates temperature noise, which is the only essential noise for thermal detectors. The dielectric constants of some materials are sufficiently temperature dependent to make a new type of bolometer feasible. The basic theory of a dielectric bolometer, as shown here, promises noise figures below 3 decibels even at chopper frequencies well above the 1/tau value of the detector. Ferroelectrics such as barium-strontium titanate and others seem to be well suited for radiation-cooled dielectric bolometers.

  12. Radiation detectors as surveillance monitors for IAEA safeguards

    SciTech Connect

    Fehlau, P.E.; Dowdy, E.J.

    1980-10-01

    Radiation detectors used for personnel dosimetry are examined for use under IAEA Safeguards as monitors to confirm the passage or nonpassage (YES/NO) of plutonium-bearing nuclear material at barrier penetrations declared closed. In this application where backgrounds are ill defined, no advantage is found for a particular detector type because of intrinsic efficiency. Secondary considerations such as complexity, ease of tamper-proofing, and ease of readout are used to recommend specific detector types for routine monitoring and for data-base measurements. Recommendations are made for applications, data acquisition, and instrument development.

  13. R&D for Better Nuclear Security: Radiation Detector Materials

    SciTech Connect

    Kammeraad, J E

    2009-04-02

    I am going to talk about the need for better materials for radiation detectors. I believe that government investment in this area can enable transformational technology change that could impact domestic nuclear security and also national nuclear security in some very positive and powerful ways. I'm not going to give you a lecture on how radiation detectors work, but I am going to tell you a bit about today's off-the-shelf technology and why it is not sufficient, what we need, and what security benefit you could get from improvements. I think we're at a critical point in time for some very impactful investments. In particular I'm going to focus on the use of gamma-ray radiation detectors at ports of entry. Not long before DHS was formed, Congress decreed that counter measures against the delivery of radiological and nuclear threats would be put in place at US ports of entry, under the authority of US Customs (later Customs and Border Protection in DHS). This included the screening of all cars and trucks passing through a port of entry. Existing off-the-shelf radiation detectors had to be selected for this purpose. Plans were made to make the most of the available technologies, but there are some inherent limitations of these detectors, plus the operational setting can bring out other limitations.

  14. Radiation detector for use in nuclear reactors

    SciTech Connect

    Cisco, T.C.; Grimaila, A.G.

    1981-09-08

    A multi-sensor radiation detection system for removable insertion into a nuclear reactor is described in which one conductor of all the sensors is a single, common element. This single common element is contained within a tubular metallic sheath and in crosssection comprises a multiple radial armed metallic conductor having a star shaped cross-section dimensioned to form wedgeshaped compartments throughout the active radiation detecting length of the metallic sheath.

  15. Semiconductor radiation detector with internal gain

    DOEpatents

    Iwanczyk, Jan (Los Angeles, CA); Patt, Bradley E. (Sherman Oaks, CA); Vilkelis, Gintas (Westlake Village, CA)

    2003-04-01

    An avalanche drift photodetector (ADP) incorporates extremely low capacitance of a silicon drift photodetector (SDP) and internal gain that mitigates the surface leakage current noise of an avalanche photodetector (APD). The ADP can be coupled with scintillators such as CsI(Tl), NaI(Tl), LSO or others to form large volume scintillation type gamma ray detectors for gamma ray spectroscopy, photon counting, gamma ray counting, etc. Arrays of the ADPs can be used to replace the photomultiplier tubes (PMTs) used in conjunction with scintillation crystals in conventional gamma cameras for nuclear medical imaging.

  16. Miniature Low Energy Electron Detector for Radiation Environment Studies

    NASA Astrophysics Data System (ADS)

    Hajdas, W.; Eggel, Ch.; Kotlinski, D.; Mshedlishvili, A.; Schmitt, B.

    We present a miniature particle monitor for space -- Low Energy Electron Detector LEED The instrument is based on the Si microstrip MYTHEN detector made in PSI for the synchrotron X-ray detection Its version for space is designed to detect low energy electrons in the planetary radiation belts and for monitoring of the Interplanetary Space Weather LEED will perform measurements of electrons in the energy range from few up to few hundred keV with energy resolution of several keV The detector is characterised by very high counting rate ability of up to 1 4 million counts per second per strip and a miniature radiation hard ASIC read-out chip serving for 128 detection channels Other features are very small size and weight as well as minimum power consumption This makes LEED also very beneficial for radiation detection at remote locations like nearby of the other planets of the solar system To date a demonstration model of the monitor was tested using radioactive sources and its space worthiness was verified In addition the full computer model of the detector was constructed and its response was highly optimised First implementation of the detector in space is foreseen onboard of the AlphaSat as part of the General Spacecraft Environment Monitor

  17. Superlattice detector as a fast direct detector and autocorrelator for terahertz radiation

    NASA Astrophysics Data System (ADS)

    Winnerl, Stephan; Schomburg, Ekkehard; Brandl, S.; Klappenberger, F.; Renk, Karl F.; van der Meer, Alexander F. G.; Hovenier, J. N.; van Es, R.; Klaasen, T.; Ignatov, A. A.; Ledentsov, Nikolai N.; Ustinov, Victor M.; Zhukov, Alexey E.; Kovsh, Alexey R.; Kop'ev, Petr S.

    1999-11-01

    We report on a GaAs/AlAs superlattice detector as a novel direct detector and autocorrelator for THz radiation. It is based on a doped wide-miniband GaAs/AlAs superlattice, with submonolayer AlAs barrier layers; the superlattice is operated at room temperature. THz radiation, generated by a free-electron laser and a mode locked p-Ge laser, was coupled into the superlattice via a corner cube antenna system. THz-irradiation of the biased superlattice resulted in a current reduction, which was monitored. The direct detector showed a fast response (20 ps, limited by the electronic circuit) and was robust against intense radiation pulses (peak power 10 kW). The responsivity was 100 times higher than the responsivity of detectors of comparable risetime and comparable robustness. Intense THz radiation caused a complete suppression of the current through the superlattice. This is the basis of the superlattice autocorrelator. The superlattice autocorrelator could resolve picosecond radiation pulses.

  18. Research on radiation detectors, boiling transients, and organic lubricants

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The accomplishments of a space projects research facility are presented. The subjects discussed are: (1) a study of radiation resistant semiconductor devices, (2) synthesis of high temperature organic lubricants, (3) departure from phase equilibrium during boiling transients, (4) effects of neutron irradiation on defect state in tungsten, and (5) determination of photon response function of NE-213 liquid scintillation detectors.

  19. Compensation of radiation damages for SOI pixel detector via tunneling

    E-print Network

    Yamada, Miho; Kurachi, Ikuo

    2015-01-01

    We are developing monolithic pixel detectors based on SOI technology for high energy physics, X-ray applications and so on.To employ SOI pixel detector on such radiation environments, we have to solve effects of total ionization damages (TID) for transistors which are enclosed in oxide layer.The holes which are generated and trapped in the oxide layers after irradiation affect characteristics of near-by transistors due to its positive electric field.Annealing and radiation of ultraviolet are not realistic to remove trapped holes for a fabricated detector due to thermal resistance of components and difficulty of handling. We studied compensation of TID effects by tunneling using a high-voltage. For decrease of trapped holes, applied high-voltage to buried p-well which is under oxide layer to inject the electrons into the oxide layer.In this report, recent progress of this study is shown.

  20. Two-dimensional position sensitive radiation detectors

    DOEpatents

    Mihalczo, J.T.

    1994-02-22

    Nuclear reaction detectors capable of position sensitivity with submillimeter resolution in two dimensions are each provided by placing arrays of scintillation or wavelength shifting optical fibers formed of a plurality of such optical fibers in a side-by-side relationship in X and Y directions with a layer of nuclear reactive material operatively associated with surface regions of the optical fiber arrays. Each nuclear reaction occurring in the layer of nuclear reactive material produces energetic particles for simultaneously providing a light pulse in a single optical fiber in the X oriented array and in a single optical fiber in the Y oriented array. These pulses of light are transmitted to a signal producing circuit for providing signals indicative of the X-Y coordinates of each nuclear event. 6 figures.

  1. Two-dimensional position sensitive radiation detectors

    DOEpatents

    Mihalczo, John T. (Oak Ridge, TN)

    1994-01-01

    Nuclear reaction detectors capable of position sensitivity with submillimeter resolution in two dimensions are each provided by placing arrays of scintillation or wave length shifting optical fibers formed of a plurality of such optical fibers in a side-by-side relationship in X and Y directions with a layer of nuclear reactive material operatively associated with surface regions of the optical fiber arrays. Each nuclear reaction occurring in the layer of nuclear reactive material produces energetic particles for simultaneously providing a light pulse in a single optical fiber in the X oriented array and in a single optical fiber in the Y oriented array. These pulses of light are transmitted to a signal producing circuit for providing signals indicative of the X-Y coordinates of each nuclear event.

  2. A radiation detector design mitigating problems related to sawed edges

    NASA Astrophysics Data System (ADS)

    Aurola, A.; Marochkin, V.; Tuuva, T.

    2014-12-01

    In pixelated silicon radiation detectors that are utilized for the detection of UV, visible, and in particular Near Infra-Red (NIR) light it is desirable to utilize a relatively thick fully depleted Back-Side Illuminated (BSI) detector design providing 100% Fill Factor (FF), low Cross-Talk (CT), and high Quantum Efficiency (QE). The optimal thickness of such detectors is typically less than 300?m and above 40?m and thus it is more or less mandatory to thin the detector wafer from the backside after the front side of the detector has been processed and before a conductive layer is formed on the backside. A TAIKO thinning process is optimal for such a thickness range since neither a support substrate on the front side nor lithographic steps on the backside are required. The conductive backside layer should, however, be homogenous throughout the wafer and it should be biased from the front side of the detector. In order to provide good QE for blue and UV light the conductive backside layer should be of opposite doping type than the substrate. The problem with a homogeneous backside layer being of opposite doping type than the substrate is that a lot of leakage current is typically generated at the sawed chip edges, which may increase the dark noise and the power consumption. These problems are substantially mitigated with a proposed detector edge arrangement which 2D simulation results are presented in this paper.

  3. Three-dimensional architecture for solid state radiation detectors

    DOEpatents

    Parker, S.

    1999-03-30

    A radiation-damage resistant radiation detector is formed on a substrate formed of a material doped with a first conductivity type dopant. The detector includes at least one first electrode formed of first conductivity type dopant, and at least one second electrode that is spaced-apart from the first electrode and formed of a second conductivity type dopant. Each first and second electrode penetrates into the substrate from a substrate surface, and one or more electrodes may penetrate entirely through the substrate, that is traversing from one surface to the other surface. Particulate and/or electromagnetic radiation penetrating at least a surface of the substrate releases electrons and holes in substrate regions. Because the electrodes may be formed entirely through the substrate thickness, the released charges will be a relatively small distance from at least a portion of such an electrode, e.g., a distance less than the substrate thickness. The electrons and/or holes traverse the small distance and are collected by said electrodes, thus promoting rapid detection of the radiation. By providing one or more electrodes with a dopant profile radially graded in a direction parallel to a substrate surface, an electric field results that promotes rapid collection of released electrons and said holes. Monolithic combinations of such detectors may be fabricated including CMOS electronics to process radiation signals. 45 figs.

  4. Three-dimensional architecture for solid state radiation detectors

    DOEpatents

    Parker, Sherwood (Berkeley, CA)

    1999-01-01

    A radiation-damage resistant radiation detector is formed on a substrate formed of a material doped with a first conductivity type dopant. The detector includes at least one first electrode formed of first conductivity type dopant, and at least one second electrode that is spaced-apart from the first electrode and formed of a second conductivity type dopant. Each first and second electrode penetrates into the substrate from a substrate surface, and one or more electrodes may penetrate entirely through the substrate, that is traversing from one surface to the other surface. Particulate and/or electromagnetic radiation penetrating at least a surface of the substrate releases electrons and holes in substrate regions. Because the electrodes may be formed entirely through the substrate thickness, the released charges will be a relatively small distance from at least a portion of such an electrode, e.g., a distance less than the substrate thickness. The electrons and/or holes traverse the small distance and are collected by said electrodes, thus promoting rapid detection of the radiation. By providing one or more electrodes with a dopant profile radially graded in a direction parallel to a substrate surface, an electric field results that promotes rapid collection of released electrons and said holes. Monolithic combinations of such detectors may be fabricated including CMOS electronics to process radiation signals.

  5. Examination results of the Three Mile Island radiation detector HP-R-212

    SciTech Connect

    Mueller, G.M.

    1983-12-01

    Area radiation detector HP-R-212 was removed from the Three Mile Island containment building on November 13, 1981. The detector apparently started to fail during November 1979 and by the first part of December 1979 the detector readings had degraded from 1 R/hr to 20 mR/hr. This report discusses the cause of failure, detector radiation measurement characteristics, and our estimates of the total gamma radiation dose received by the detector electronics.

  6. Multi-directional radiation detector using photographic film

    NASA Astrophysics Data System (ADS)

    Junet, L. K.; Majid, Z. A. Abdul; Sapuan, A. H.; Sayed, I. S.; Pauzi, N. F.

    2014-11-01

    Ionising radiation has always been part of our surrounding and people are continuously exposed to it. Ionising radiation is harmful to human health, thus it is vital to monitor the radiation. To monitor radiation, there are three main points that should be observed cautiously, which are energy, quantity, and direction of the radiation sources. A three dimensional (3D) dosimeter is an example of a radiation detector that provide these three main points. This dosimeter is able to record the radiation dose distribution in 3D. Applying the concept of dose detection distribution, study has been done to design a multi-directional radiation detector of different filter thicknesses. This is obtained by designing a cylinder shaped aluminum filter with several layers of different thickness. Black and white photographic material is used as a radiation-sensitive material and a PVC material has been used as the enclosure. The device is then exposed to a radiation source with different exposure factors. For exposure factor 70 kVp, 16 mAs; the results have shown that optical density (OD) value at 135° is 1.86 higher compared with an OD value at 315° which is 0.71 as the 135° area received more radiation compare to 315° region. Furthermore, with an evidence of different angle of film give different value of OD shows that this device has a multidirectional ability. Materials used to develop this device are widely available in the market, thus reducing the cost of development and making it suitable for commercialisation.

  7. Advanced technology lunar telescopes III. Radiation resistant detectors

    SciTech Connect

    Payne, L.J.; Kimble, R.A.; Smith, A.M.; Haas, J.P.; Sturgell, C.C. Jr.; Wentink, R.E.; Carbone, J.; Chen, P.C.

    1993-01-01

    A practical lunar telescope requires high resolution imaging array detectors that are immune to (or can be easily shielded from) solar flare particle radiation and cosmic rays. Charge-coupled devices (CCDs), the detectors of choice for ground-based applications, fall short in this respect because of their high susceptibility to radiation induced bulk traps and loss of charge transfer efficiency (CTE). Blooming in CCDs also limits the dynamic range and degrades resolution, while the well known red leak problem hinders observations in the ultraviolet. The authors describe an ongoing program at NASA GSFC to develop intensified random-access Charge-Injection Devices (CIDs), a new generation of space uv detectors which do not have the shortcomings of CCDs. CIDs, like CCDs, are silicon array detectors. Unlike CCDs, however, CIDs have more than 100x greater tolerance to ionizing particle radiation. Since CIDs do not transfer charge, CTE degradation has very little effect on the overall sensitivity and noise level. CIDs can perform extremely fast windowing of selected regions of interest with high signal levels (e.g. bright cores of galaxies or strong emission lines, etc) while monitoring the remainder of the array at lower rates. This selective readout ability plus the lack of blooming give CIDs a high dynamic range of operation but with minimal demands on the memory storage and telemetry data bandwidth. The authors demonstrate the operation of a row-windowing CID and discuss the potential applications of these devices to astronomical research from the moon.

  8. Device for detachably securing a collimator to a radiation detector

    SciTech Connect

    Hanz, G.J.; Jung, G.; Pflaum, M.

    1986-12-16

    A device is described for detachably securing a collimator to a radiation detector, comprising: (a) a first annular groove means secured to the radiation detector; (b) a second annular groove means secured to the collimator; (c) a split ring having a first and second ring ends, the ring being received in the first annular groove means; and (d) a ring diameter control system, including (d1) a first lever system having two ends; (d2) a second lever system having two ends; and (d3) a rotating hub being rotatably secured to the detector head; wherein the first lever system is rotatably mounted with one end linked to the first ring end and with the other end linked to the rotating hub. The second lever system is rotatably mounted with one end linked to the second ring end and with the other end linked to the rotating hub, such that rotation of the rotating hub moves the first and second lever systems in opposite directions thereby moving the first and second ring ends between a first position, in which the split ring is positioned only in the first annular groove means, and a second position, in which the split ring is located in both the first annular groove means and the second annular groove means, thus attaching the collimator to the radiation detector.

  9. Bismuth tri-iodide radiation detector development

    NASA Astrophysics Data System (ADS)

    Lintereur, Azaree T.; Qiu, Wei; Nino, Juan C.; Baciak, James E.

    2009-08-01

    Bismuth tri-iodide (BiI3), a wide band-gap semiconductor, demonstrates many of the material properties necessary for high resolution room temperature gamma-ray spectroscopy. These material properties include high density, large bandgap, and high atomic number. The theoretical intrinsic photopeak efficiency of BiI3 is approximately 2-3 times higher than CdZnTe over the range of 200-3000 keV. BiI3 has a theoretical intrinsic photopeak efficiency of 19% at 662 keV, compared to CdZnTe which has a theoretical intrinsic photopeak efficiency of 13% at 662 keV. A modified vertical Bridgman growth method is being used to grow large, greater than 100 mm3, single BiI3 crystals. Growth parameter optimization has demonstrated that single crystals can be obtained with temperature gradients of 10°/cm or 15o/cm and a growth rate of 0.5 mm/hr, or with a temperature gradient of 10o/cm and a growth rate of 1 mm/hr. Polycrystalline material results from all other growth parameter combinations. X-ray diffraction spectra are used to determine if the crystals are single crystals or polycrystalline. UV-VIS spectra analysis has revealed that the band-gap of BiI3 is 1.72 eV. The resistivity of the crystals has been determined by generating I-V curves to be on the order of 108-109 ?-cm. Zone refining is being performed to increase the purity of the starting material and the resistivity of the crystals. Detectors have been fabricated with both gold and palladium electrodes.

  10. Virtual detector of synchrotron radiation (VDSR) - A C++ parallel code for particle tracking and radiation calculation

    SciTech Connect

    Rykovanov, S. G.; Chen, M.; Geddes, C. G. R.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2012-12-21

    The Virtual Detector for Synchrotron Radiation (VDSR) is a parallel C++ code developed to calculate the incoherent radiation from a single charged particle or a beam moving in given external electro-magnetic fields. In this proceedings the code structure and features are introduced. An example of radiation generation from the betatron motion of a beam in the focusing fields of the wake in a laser-plasma accelerator is presented.

  11. Virtual detector of synchrotron radiation (VDSR) - A C++ parallel code for particle tracking and radiation calculation

    NASA Astrophysics Data System (ADS)

    Rykovanov, S. G.; Chen, M.; Geddes, C. G. R.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2012-12-01

    The Virtual Detector for Synchrotron Radiation (VDSR) is a parallel C++ code developed to calculate the incoherent radiation from a single charged particle or a beam moving in given external electro-magnetic fields. In this proceedings the code structure and features are introduced. An example of radiation generation from the betatron motion of a beam in the focusing fields of the wake in a laser-plasma accelerator is presented.

  12. Super-thin single crystal diamond membrane radiation detectors

    SciTech Connect

    Pomorski, Michal; Caylar, Benoit; Bergonzo, Philippe

    2013-09-09

    We propose to use the non-electronic grade (nitrogen content 5 ppb < [N] < 5 ppm) single crystal (sc) chemical vapour deposited (CVD) diamond as a thin-membrane radiation detector. Using deep Ar/O{sub 2} plasma etching it is possible to produce self-supported few micrometres thick scCVD membranes of a size approaching 7 mm × 7 mm, with a very good surface quality. After metallization and contacting, electrical properties of diamond membrane detectors were probed with 5.486 MeV ?-particles as an ionization source. Despite nitrogen impurity, scCVD membrane detectors exhibit stable operation, charge collection efficiency close to 100%, with homogenous response, and extraordinary dielectric strength up to 30 V/?m.

  13. Charge transport properties of CdMnTe radiation detectors

    SciTech Connect

    Kim K.; Rafiel, R.; Boardman, M.; Reinhard, I.; Sarbutt, A.; Watt, G.; Watt, C.; Uxa, S.; Prokopovich, D.A.; Belas, E.; Bolotnikov, A.E.; James, R.B.

    2012-04-11

    Growth, fabrication and characterization of indium-doped cadmium manganese telluride (CdMnTe)radiation detectors have been described. Alpha-particle spectroscopy measurements and time resolved current transient measurements have yielded an average charge collection efficiency approaching 100 %. Spatially resolved charge collection efficiency maps have been produced for a range of detector bias voltages. Inhomogeneities in the charge transport of the CdMnTe crystals have been associated with chains of tellurium inclusions within the detector bulk. Further, it has been shown that the role of tellurium inclusions in degrading chargecollection is reduced with increasing values of bias voltage. The electron transit time was determined from time of flight measurements. From the dependence of drift velocity on applied electric field the electron mobility was found to be n = (718 55) cm2/Vs at room temperature.

  14. Super-thin single crystal diamond membrane radiation detectors

    NASA Astrophysics Data System (ADS)

    Pomorski, Michal; Caylar, Benoit; Bergonzo, Philippe

    2013-09-01

    We propose to use the non-electronic grade (nitrogen content 5 ppb < [N] < 5 ppm) single crystal (sc) chemical vapour deposited (CVD) diamond as a thin-membrane radiation detector. Using deep Ar/O2 plasma etching it is possible to produce self-supported few micrometres thick scCVD membranes of a size approaching 7 mm × 7 mm, with a very good surface quality. After metallization and contacting, electrical properties of diamond membrane detectors were probed with 5.486 MeV ?-particles as an ionization source. Despite nitrogen impurity, scCVD membrane detectors exhibit stable operation, charge collection efficiency close to 100%, with homogenous response, and extraordinary dielectric strength up to 30 V/?m.

  15. Modeling radiation loads to detectors in a SNAP mission

    SciTech Connect

    Nikolai V. Mokhov et al.

    2004-05-12

    In order to investigate degradation of optical detectors of the Supernova Acceleration Project (SNAP) space mission due to irradiation, a three-dimensional model of the satellite has been developed. Realistic radiation environment at the satellite orbit, including both galactic and trapped in radiation belts cosmic rays, has been taken into account. The modeling has been performed with the MARS14 Monte Carlo code. In a current design, the main contribution to dose accumulated in the photodetectors is shown to be due to trapped protons. A contribution of primary {alpha}-particles is estimated. Predicted performance degradation for the photo-detector for a 4-year space mission is 40% and can be reduced further by means of shielding optimization.

  16. Experiences with radiation portal detectors for international rail transport

    SciTech Connect

    Stromswold, David C.; McCormick, Kathleen R.; Todd, Lindsay C.; Ashbaker, Eric D.; Evans, J. C.

    2006-08-30

    Radiation detectors monitored trains at two international borders to evaluate the performance of NaI(Tl) and plastic (polyvinyltoluene: PVT) gamma-ray detectors to characterize rail cargo. The detectors included a prototype NaI(Tl) radiation-portal-monitor panel having four large detectors (10-cm × 10-cm × 41-cm) and a PVT panel with a 41 cm × 173 cm × 3.8-cm detector. Spectral data from the NaI(Tl) and PVT detectors were recorded. Of particular emphasis was the identification of naturally occurring radioactive material (NORM) and the resultant frequency of nuisance alarms. For rail monitoring, the difficulty in stopping trains to perform secondary inspection on alarming cars creates a need for reliable identification of NORM during initial screening. Approximately 30 trains were monitored, and the commodities in individual railcars were ascertained from manifest information. At one test site the trains carried inter-modal containers that had been unloaded from ships, and at the other site the trains contained bulk cargo or individual items in boxcars or flatbeds. NORM encountered included potash, liquefied petroleum gas, fireworks, televisions, and clay-based products (e.g., pottery). Analysis of the spectral data included the use of the template-fitting program GADRAS/FitToDB from Sandia National Laboratories. For much of the NORM the NaI(Tl) data produced a correct identification of the radionuclides present in the railcars. The same analysis was also used for PVT data in which the spectral information (no peaks but only gradual spectral changes including Compton edges) was limited. However, the PVT analysis provided correct identification of 40K and 226Ra in many cases.

  17. Experiences with radiation portal detectors for international rail transport

    NASA Astrophysics Data System (ADS)

    Stromswold, D. C.; McCormick, K.; Todd, L.; Ashbaker, E. D.; Evans, J. C.

    2006-08-01

    Radiation detectors monitored trains at two international borders to evaluate the performance of NaI(Tl) and plastic (polyvinyltoluene: PVT) gamma-ray detectors to characterize rail cargo. The detectors included a prototype NaI(Tl) radiation-portal-monitor panel having four large detectors (10-cm × 10-cm × 41-cm) and a PVT panel with a 41 cm × 173 cm × 3.8-cm detector. Spectral data from the NaI(Tl) and PVT detectors were recorded. Of particular emphasis was the identification of naturally occurring radioactive material (NORM) and the resultant frequency of nuisance alarms. For rail monitoring, the difficulty in stopping trains to perform secondary inspection on alarming cars creates a need for reliable identification of NORM during initial screening. Approximately 30 trains were monitored, and the commodities in individual railcars were ascertained from manifest information. At one test site, the trains carried inter-modal containers that had been unloaded from ships, and at the other site, the trains contained bulk cargo in tanker cars and hopper cars or individual items in boxcars or flatbeds. NORM encountered included potash, liquefied petroleum gas, fireworks, televisions, and clay-based products (e.g., pottery). Analysis of the spectral data included the use of the template-fitting portion of the program GADRAS developed at Sandia National Laboratories. For most of the NORM, the NaI(Tl) data produced a correct identification of the radionuclides present in the railcars. The same analysis was also used for PVT data in which the spectral information (no peaks but only gradual spectral changes including Compton edges) was limited. However, the PVT analysis provided correct identification of 40K and 226Ra in many cases.

  18. Calibration of the active radiation detector for Spacelab-One

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The flight models of the active radiation detector (ARD) for the ENV-01 environmental monitor were calibrated using gamma radiation. Measured sensitivities of the ion chambers were 6.1 + or - 0.3 micron rad per count for ARD S/N1, and 10.4 + or - 0.5 micron rad per count for ARD S/N2. Both were linear over the measured range 0.10 to 500 m/rad hour. The particle counters (proportional counters) were set to respond to approximately 85% of minimum ionizing particles of unit charge passing through them. These counters were also calibrated in the gamma field.

  19. Dielectric Resonators as Radiation Detectors at Low Temperatures

    NASA Astrophysics Data System (ADS)

    Yamasaki, N. Y.; Sekiya, N.; Kikuchi, T.; Hoshino, M.; Mitsuda, K.; Sato, K.

    2015-10-01

    GHz LC resonators whose resonance frequency depends on temperature may be put to use as radiation detectors. We have demonstrated that a resonator utilizing STO (SrTiO) at 4 and 2 K detected infrared light emitting diode (LED) light, by a shift of resonance frequency around 2 GHz. A suitable design of a resonator array with temperature-dependent dielectric material will be used as a large-format microcalorimeter array without or with only very small Johnson noise.

  20. Simple classical model for Fano statistics in radiation detectors

    NASA Astrophysics Data System (ADS)

    Jordan, David V.; Renholds, Andrea S.; Jaffe, John E.; Anderson, Kevin K.; René Corrales, L.; Peurrung, Anthony J.

    2008-02-01

    A simple classical model that captures the essential statistics of energy partitioning processes involved in the creation of information carriers (ICs) in radiation detectors is presented. The model pictures IC formation from a fixed amount of deposited energy in terms of the statistically analogous process of successively sampling water from a large, finite-volume container ("bathtub") with a small dipping implement ("shot or whiskey glass"). The model exhibits sub-Poisson variance in the distribution of the number of ICs generated (the "Fano effect"). Elementary statistical analysis of the model clarifies the role of energy conservation in producing the Fano effect and yields Fano's prescription for computing the relative variance of the IC number distribution in terms of the mean and variance of the underlying, single-IC energy distribution. The partitioning model is applied to the development of the impact ionization cascade in semiconductor radiation detectors. It is shown that, in tandem with simple assumptions regarding the distribution of energies required to create an (electron, hole) pair, the model yields an energy-independent Fano factor of 0.083, in accord with the lower end of the range of literature values reported for silicon and high-purity germanium. The utility of this simple picture as a diagnostic tool for guiding or constraining more detailed, "microscopic" physical models of detector material response to ionizing radiation is discussed.

  1. Semiconductors for room-temperature radiation detector applications 2

    SciTech Connect

    James, R.B.; Schlesinger, T.E.; Siffert, P.; O`Connell, M.; Cuzin, M.

    1998-12-31

    The purpose of the symposium was to provide a forum for presenting and evaluating the most recent results on semiconductor radiation detectors for use in the energy range of a few eV to about 5 MeV. The primary emphasis of the papers was on developing semiconductor X-ray and gamma-ray detectors and imagers which combine the advantages of room-temperature operation with the excellent energy resolution of cryogenically cooled spectrometers. By eliminating the cryogen, new radiation-sensing instruments, such as spectrometers and imagers, can be manufactured that are portable, easy to operate, and relatively maintenance-free. The symposium was organized into technical sessions on cadmium zinc telluride, mercuric iodide, imagers, fabrication and processing, device modeling, II-VI materials (including a joint session with the symposium on infrared materials and technology), cadmium telluride, vapor-deposited materials, lead iodide, group IV materials, and radiation damage. The primary emphasis however, was clearly on cadmium zinc telluride (CZT), as this material has resulted in significant progress in the development of single detectors, imagers, and systems appropriate for a number of applications. Separate abstracts were prepared for most papers in the volume.

  2. Simple classical model for Fano statistics in radiation detectors

    SciTech Connect

    Jordan, David V.; Renholds, Andrea S.; Jaffe, John E.; Anderson, Kevin K.; Corrales, L. Rene; Peurrung, Anthony J.

    2008-02-01

    A simple classical model that captures the essential statistics of energy partitioning processes involved in the creation of information carriers (ICs) in radiation detectors is presented. The model pictures IC formation from a fixed amount of deposited energy in terms of the statistically analogous process of successively sampling water from a large, finite-volume container (“bathtub”) with a small dipping implement (“shot glass”). The model exhibits sub-Poisson variance in the distribution of the number of ICs generated (the “Fano e_ect”). Elementary statistical analysis of the model clarifies the role of energy conservation in producing the Fano e_ect and yields Fano’s prescription for relating the IC number distribution to the mean and variance of the underlying IC energy distribution. The connection between the model and energy partitioning in semiconductor radiation detectors is illustrated, and the implications of this simple picture for guiding or constraining more detailed, “microscopic” physical models of detector material response to ionizing radiation are discussed.

  3. Radiation tests for a single-GEM-loaded gaseous detector

    NASA Astrophysics Data System (ADS)

    Lee, Kyong Sei; Hong, Byungsik; Park, Sung Keun; Kim, Sang Yeol

    2014-11-01

    We report on a systematic study of a single-gas-electron-multiplier (GEM)-loaded gaseous detector developed for precision measurements of high-energy particle beams and for dose verification in particle therapy. In the present study, a 256-channel prototype detector having an active area of 16 × 16 cm2 and operating using a continuous current-integration-mode signal-processing method was manufactured and tested with X-rays emitted from a 70-kV X-ray generator and 43-MeV protons provided by the MC50 proton cyclotron at the Korea Institute of Radiological and Medical Science (KIRAMS). The amplified detector response was measured for X-rays with an intensity of about 5 × 106 Hz cm-2. The linearity of the detector response to the particle flux was examined and validated by using 43-MeV proton beams. The non-uniform development of the amplification for the gas electrons in space was corrected by applying a proper calibration to the channel responses of the measured beam-profile data. We conclude from the radiation tests that the detector developed in the present study will allow us to perform quality measurements of various high-energy particle beams and to apply the technology to dose-verification measurements in particle therapy.

  4. System for determining the type of nuclear radiation from detector output pulse shape

    DOEpatents

    Miller, William H. (Columbia, MO); Berliner, Ronald R. (Columbia, MO)

    1994-01-01

    A radiation detection system determines the type of nuclear radiation received in a detector by producing a correlation value representative of the statistical cross correlation between the shape of the detector signal and pulse shape data previously stored in memory and characteristic of respective types of radiation. The correlation value is indicative of the type of radiation. The energy of the radiation is determined from the detector signal and is used to produce a spectrum of radiation energies according to radiation type for indicating the nature of the material producing the radiation.

  5. System for determining the type of nuclear radiation from detector output pulse shape

    DOEpatents

    Miller, W.H.; Berliner, R.R.

    1994-09-13

    A radiation detection system determines the type of nuclear radiation received in a detector by producing a correlation value representative of the statistical cross correlation between the shape of the detector signal and pulse shape data previously stored in memory and characteristic of respective types of radiation. The correlation value is indicative of the type of radiation. The energy of the radiation is determined from the detector signal and is used to produce a spectrum of radiation energies according to radiation type for indicating the nature of the material producing the radiation. 2 figs.

  6. Investigation of radiation doses in open space using TLD detectors.

    PubMed

    Reitz, G; Facius, R; Bilski, P; Olko, P

    2002-01-01

    The low energy component of the cosmic radiation field is strongly modified by the shielding of the spacecraft and it is time and location dependent. Thermoluminescent lithium fluoride detectors have been applied to determine the radiation doses inside the ESA-Facility BIOPAN. The BIOPAN facility was mounted outside and launched on a Foton spacecraft and opened to space to allow exposure of several experiments to open space. Standard TLD-600. TLD-700 chips, two layers MTS-Ns sintered pellets with different effective thickness of the sensitive layer and MTS-N of different thickness have been exposed with different shielding thicknesses in front of them. The measured TL signal in the 0.1 mm thick detector just shielded by an aluminised Kapton foil of 25 microm thickness in front yielded a dose of 29.8 Gy (calibrated with 137Cs gamma rays) for an exposure time of 12.7 days: after 2.5 g.cm(-2) shielding the doses dropped to 3 mGy. The monitoring of radiation doses and its depth dose distribution outside the spacecraft are of great interest for radiation protection of astronauts working in open space. The knowledge of depth-dose distribution is a prerequisite to determine the organ doses an astronaut will receive during an extravehicular activity (EVA). The BIOPAN experiments are to be continued in the future. PMID:12382937

  7. Field Testing of a Portable Radiation Detector and Mapping System

    SciTech Connect

    Hofstetter, K.J.; Hayes, D.W.; Eakle, R.F.

    1998-03-01

    Researchers at the Savannah River Site (SRS) have developed a man- portable radiation detector and mapping system (RADMAPS) which integrates the accumulation of radiation information with precise ground locations. RADMAPS provides field personnel with the ability to detect, locate, and characterize nuclear material at a site or facility by analyzing the gamma or neutron spectra and correlating them with position. the man-portable field unit records gamma or neutron count rate information and its location, along with date and time, using an embedded Global Positioning System (GPS). RADMAPS is an advancement in data fusion, integrating several off-the-shelf technologies with new computer software resulting in a system that is simple to deploy and provides information useful to field personnel in an easily understandable form. Decisions on subsequent actions can be made in the field to efficiently use available field resources. The technologies employed in this system include: recording GPS, radiation detection (typically scintillation detectors), pulse height analysis, analog-to-digital converters, removable solid-state (Flash or SRAM) memory cards, Geographic Information System (GIS) software and personal computers with CD-ROM supporting digital base maps. RADMAPS includes several field deployable data acquisition systems designed to simultaneously record radiation and geographic positions. This paper summarizes the capabilities of RADMAPS and some of the results of field tests performed with the system.

  8. Radiation detectors obtained using neutron-transmutation-doped silicon

    NASA Astrophysics Data System (ADS)

    Halmagean, Eugenia T.; Lazarovici, Doina N.; Lazarovici, Cristian C.

    1992-12-01

    High resistivity (over 10.0 kilohm.cm) extrinsic P-type Si was produced from high pure P- type Si (resistivity between 1.0 and 2.5 kilohm.cm, lifetime over 1 ms), using the neutron transmutation doping technique. Material obtained by this method, used for detectors, has better properties in dopant homogeneity and controllability than conventionally doped ones. Improved radiation detectors of the surface barrier type were obtained by deposition of amorphous Ge and Al, Au, respectively, for contacts. Results obtained by testing two types of detection structures are presented. The first type, for gamma radiation, are of a sensitive area of 100 square mm and a sensitive depth of 300 micrometers . They present a good response for Cs- 137, higher than 400 p/s/cGy/h. The second type, for alpha-radiation (2...9 MeV) and beta- radiation (225 keV...2.26 MeV), are of a sensitive area of 5 square cm and a sensitive depth of 250 micrometers . Calibration was done obtaining: R(subscript (alpha) ) equals min.1 p.square cm/s.Bq for Am-241 (5.45 MeV) and R(subscript (beta) ) equals min.0.7 p.square cm/s.Bq for Sr-90+ Y-90 (2.26 MeV). Original results concerning functioning tests of these detectors in special conditions such as temperatures between -25 degree(s)C and +45 degree(s)C, humidity 90% at 30 degree(s)C, and mechanical shocks are presented.

  9. Applications of Noble Gas Radiation Detectors to Counter-terrorism

    NASA Astrophysics Data System (ADS)

    Vanier, Peter E.; Forman, Leon

    2002-10-01

    Radiation detectors are essential tools in the detection, analysis and disposition of potential terrorist devices containing hazardous radioactive and/or fissionable materials. For applications where stand-off distance and source shielding are limiting factors, large detectors have advantages over small ones. The ability to distinguish between Special Nuclear Materials and false-positive signals from natural or man-made benign sources is also important. Ionization chambers containing compressed noble gases, notably xenon and helium-3, can be scaled up to very large sizes, improving the solid angle for acceptance of radiation from a distant source. Gamma spectrometers using Xe have a factor of three better energy resolution than NaI scintillators, allowing better discrimination between radioisotopes. Xenon detectors can be constructed so as to have extremely low leakage currents, enabling them to operate for long periods of time on batteries or solar cells. They are not sensitive to fluctuations in ambient temperature, and are therefore suitable for deployment in outdoor locations. Position-sensitive 3He chambers have been built as large as 3000 cm2, and with spatial resolution of less than 1 mm. Combined with coded apertures made of cadmium, they can be used to create images of thermal neutron sources. The natural background of spallation neutrons from cosmic rays generates a very low count rate, so this instrument could be quite effective at identifying a man-made source, such as a spontaneous fission source (Pu) in contact with a moderator (high explosive).

  10. Radiation effects in Low Gain Avalanche Detectors after hadron irradiations

    NASA Astrophysics Data System (ADS)

    Kramberger, G.; Baselga, M.; Cindro, V.; Fernandez-Martinez, P.; Flores, D.; Galloway, Z.; Gorišek, A.; Greco, V.; Hidalgo, S.; Fadeyev, V.; Mandi?, I.; Mikuž, M.; Quirion, D.; Pellegrini, G.; Sadrozinski, H. F.-W.; Studen, A.; Zavrtanik, M.

    2015-07-01

    Novel silicon detectors with charge gain were designed (Low Gain Avalanche Detectors - LGAD) to be used in particle physics experiments, medical and timing applications. They are based on a n++-p+-p structure where appropriate doping of multiplication layer (p^+) is needed to achieve high fields and impact ionization. Several wafers were processed with different junction parameters resulting in gains of up to 16 at high voltages. In order to study radiation hardness of LGAD, which is one of key requirements for future high energy experiments, several sets of diodes were irradiated with reactor neutrons, 192 MeV pions and 800 MeV protons to the equivalent fluences of up to ?eq=1016 cm-2. Transient Current Technique and charge collection measurements with LHC speed electronics were employed to characterize the detectors. It was found that the gain decreases with irradiation, which was attributed to effective acceptor removal in the multiplication layer. Other important aspects of operation of irradiated detectors such as leakage current and noise in the presence of charge multiplication were also investigated.

  11. Porous Silicon-Based Quantum Dot Broad Spectrum Radiation Detector

    PubMed Central

    Urdaneta, M.; Stepanov, P.; Weinberg, I. N.; Pala, I. R.; Brock, S.

    2013-01-01

    Silicon is a convenient and inexpensive platform for radiation detection, but has low stopping power for x-rays and gamma-rays with high energy (e.g., 100 keV, as used in computed tomography and digital radiography, or 1 MeV, as desired for detection of nuclear materials). We have effectively increased the stopping power of silicon detectors by producing a layer of porous or micro-machined silicon, and infusing this layer with semiconductor quantum dots made of electron-dense materials. Results of prototype detectors show sensitivity to infrared, visible light, and x-rays, with dark current of less than 1 nA/mm2. PMID:24432047

  12. Intrinsic Radiation in Lutetium Based PET Detector: Advantages and Disadvantages

    E-print Network

    Wei, Qingyang

    2015-01-01

    Lutetium (Lu) based scintillators such as LSO and LYSO, are widely used in modern PET detectors due to their high stopping power for 511 keV gamma rays, high light yield and short decay time. However, 2.6% of naturally occurring Lu is 176Lu, a long-lived radioactive element including a beta decay and three major simultaneous gamma decays. This phenomenon introduces random events to PET systems that affects the system performance. On the other hand, the advantages of intrinsic radiation of 176Lu (IRL) continues to be exploited. In this paper, research literatures about IRL in PET detectors are reviewed. Details about the adverse effects of IRL to PET and their solutions, as well as the useful applications are presented and discussed.

  13. Porous Silicon-Based Quantum Dot Broad Spectrum Radiation Detector.

    PubMed

    Urdaneta, M; Stepanov, P; Weinberg, I N; Pala, I R; Brock, S

    2011-01-11

    Silicon is a convenient and inexpensive platform for radiation detection, but has low stopping power for x-rays and gamma-rays with high energy (e.g., 100 keV, as used in computed tomography and digital radiography, or 1 MeV, as desired for detection of nuclear materials). We have effectively increased the stopping power of silicon detectors by producing a layer of porous or micro-machined silicon, and infusing this layer with semiconductor quantum dots made of electron-dense materials. Results of prototype detectors show sensitivity to infrared, visible light, and x-rays, with dark current of less than 1 nA/mm(2). PMID:24432047

  14. Gold-coated copper cone detector as a new standard detector for F2 laser radiation at 157 nm

    SciTech Connect

    Kueck, Stefan; Brandt, Friedhelm; Taddeo, Mario

    2005-04-20

    A new standard detector for high-accuracy measurements of F2 laser radiation at 157 nm is presented. This gold-coated copper cone detector permits the measurement of average powers up to 2 W with an uncertainty of {approx}1%. To the best of our knowledge, this is the first highly accurate standard detector for F2 laser radiation for this power level. It is fully characterized according to Guide to the Expression of Uncertainty in Measurement of the International Organization for Standardization and is connected to the calibration chain for laser radiation established by the German National Metrology Institute.

  15. IceCube: A Cubic Kilometer Radiation Detector

    SciTech Connect

    IceCube Collaboration; Klein, Spencer R; Klein, S.R.

    2008-06-01

    IceCube is a 1 km{sup 3} neutrino detector now being built at the Amudsen-Scott South Pole Station. It consists of 4800 Digital Optical Modules (DOMs) which detect Cherenkov radiation from the charged particles produced in neutrino interactions. IceCube will observe astrophysical neutrinos with energies above about 100 GeV. IceCube will be able to separate {nu}{sub {mu}}, {nu}{sub t}, and {nu}{sub {tau}} interactions because of their different topologies. IceCube construction is currently 50% complete.

  16. High field CdS detector for infrared radiation

    NASA Technical Reports Server (NTRS)

    Tyagi, R. C.; Robertson, J. B.; Boer, K. W.; Hadley, H. C., Jr. (inventors)

    1974-01-01

    An infrared radiation detector including a cadmium sulfide platelet having a cathode formed on one of its ends and an anode formed on its other end is presented. The platelet is suitably doped such that stationary high-field domains are formed adjacent the cathode when based in the negative differential conductivity region. A negative potential is applied to the cathode such that a high-field domain is formed adjacent to the cathode. A potential measuring probe is located between the cathode and the anode at the edge of the high-field domain and means are provided for measuring the potential at the probe whereby this measurement is indicative of the infrared radiation striking the platelet.

  17. Low Energy Electron Detector for Space Radiation Measurements

    NASA Astrophysics Data System (ADS)

    Hajdas, Wojtek

    Low Energy Electron Detector LEED is a miniature particle monitor for measurements in space. It is based on the MYTHEN Si-microstrip system made at Paul Scherrer Institut PSI for X-ray detection at the Synchrotron Light Source SLS. It was designed in collaboration with the European Space Agency ESA in order to provide a new instrument covering an unexplored energy range of space electrons below few tens of keV. A lack of measurements and realtime data both at low and high energies of particle as well as difficulties in radiation belts modeling are still persisting even after 40 years from their discovery. In particular the low energy electrons, up to few hundred keV are particularly poorly studied. Such electrons can shed a new light on the acceleration and trapping processes and on the dynamics of radiation belts. Measurements of electrons in wide range of energies can provide a link between hot plasma and trapped higher energy particles. The long term observations can probe and verify a coupling between Sun and Earth magnetosphere. On the spacecraft environment side, the electrons with energies of tens of keV can create radiation hazard for on-board instruments, induce spacecraft charging and increase the background in precise X-ray observations. Therefore the requirements put on monitors devoted for above studies are very demanding and often opposing. A special care in construction of LEED - the space version of MYTHEN was optimizing it for very high fluxes and harsh radiation environment. The device aims to monitor Space Weather, map planetary Radiation Belts and study hot plasmas and particle acceleration. It will detect electrons with energies from few up to few hundred keV with energy resolution of several keV. The detector is characterized by ability to deal with very high counting rate of up to 1.4 million counts per second per strip. Its core is a PSI developed radiation hard ASIC read-out chip serving for 128 detection channels. The main design features of LEED are small size and weight as well as minimized power consumption. This makes it also very beneficial for radiation detection at remote locations like peripheries of other planets of the solar system. The LEED demonstration model has been constructed and first qualification measurements with electron beams are being performed. In parallel, the radiation hardness tests of electronic components are prepared at the PSI Proton Irradiation Facility PIF to qualify its critical parts for the flight version. The full computer model of the detector was constructed using GEANT4 package from CERN. It allowed for improvement of the detector response and study background rejection methods. Development of LEED is supported by the Swiss Space Office and ESA. Future possible implementation on-board of the International Space Station and on micro-satellites is currently investigated.

  18. Correlation between the surface roughness and the leakage current of an SSB radiation detector

    NASA Astrophysics Data System (ADS)

    Kim, Han Soo; Park, Se Hwan; Kim, Yong Kyun; Ha, Jang Ho; Kang, Sang Mook; Cho, Seung Yeon

    2007-08-01

    Leakage current is one of the main noise sources of in radiation detectors, especially in a semiconductor radiation detector used for energy spectroscopy. A Silicon Surface Barrier (SSB) radiation detector was constructed to study the correlation between its surface roughness and leakage current. The surface roughness was analyzed with an Atomic Force Microscopy (AFM). All the constructed SSB radiation detectors in this study were processed in same way, but the etching solutions used to roughen the silicon surface were different. The correlation coefficient between the surface roughness and the leakage current was 0.848. This value indicates that the surface roughness and the leakage current have a relatively strong relationship, and a proper etching condition can minimize the leakage current in a semiconductor radiation detector based on silicon. The energy spectrum for an alpha particle from 238Pu was also measured with the constructed SSB radiation detector.

  19. Seismic restraint means for a nuclear radiation detector mounted in a tubular thimble

    SciTech Connect

    Underwood, R.H.; Todt, W.H.

    1985-03-12

    Seismic restraint means are provided for mounting an elongated, generally cylindrical nuclear radiation detector within a tubular thimble. The restraint means permits longitudinal movement of the restraint means and the radiation detector into and out of the thimble. The restraint means includes spring bias means and thimble constant means whereby the contact means engage the thimble with a constant predetermined force which minimizes seismic vibration action on the radiation detector.

  20. Processing and characterization of epitaxial GaAs radiation detectors

    NASA Astrophysics Data System (ADS)

    Wu, X.; Peltola, T.; Arsenovich, T.; Gädda, A.; Härkönen, J.; Junkes, A.; Karadzhinova, A.; Kostamo, P.; Lipsanen, H.; Luukka, P.; Mattila, M.; Nenonen, S.; Riekkinen, T.; Tuominen, E.; Winkler, A.

    2015-10-01

    GaAs devices have relatively high atomic numbers (Z=31, 33) and thus extend the X-ray absorption edge beyond that of Si (Z=14) devices. In this study, radiation detectors were processed on GaAs substrates with 110 - 130 ?m thick epitaxial absorption volume. Thick undoped and heavily doped p+ epitaxial layers were grown using a custom-made horizontal Chloride Vapor Phase Epitaxy (CVPE) reactor, the growth rate of which was about 10 ?m / h. The GaAs p+/i/n+ detectors were characterized by Capacitance Voltage (CV), Current Voltage (IV), Transient Current Technique (TCT) and Deep Level Transient Spectroscopy (DLTS) measurements. The full depletion voltage (Vfd) of the detectors with 110 ?m epi-layer thickness is in the range of 8-15 V and the leakage current density is about 10 nA/cm2. The signal transit time determined by TCT is about 5 ns when the bias voltage is well above the value that produces the peak saturation drift velocity of electrons in GaAs at a given thickness. Numerical simulations with an appropriate defect model agree with the experimental results.

  1. Ambient temperature cadmium zinc telluride radiation detector and amplifier circuit

    DOEpatents

    McQuaid, James H. (Livermore, CA); Lavietes, Anthony D. (Hayward, CA)

    1998-05-29

    A low noise, low power consumption, compact, ambient temperature signal amplifier for a Cadmium Zinc Telluride (CZT) radiation detector. The amplifier can be used within a larger system (e.g., including a multi-channel analyzer) to allow isotopic analysis of radionuclides in the field. In one embodiment, the circuit stages of the low power, low noise amplifier are constructed using integrated circuit (IC) amplifiers , rather than discrete components, and include a very low noise, high gain, high bandwidth dual part preamplification stage, an amplification stage, and an filter stage. The low noise, low power consumption, compact, ambient temperature amplifier enables the CZT detector to achieve both the efficiency required to determine the presence of radio nuclides and the resolution necessary to perform isotopic analysis to perform nuclear material identification. The present low noise, low power, compact, ambient temperature amplifier enables a CZT detector to achieve resolution of less than 3% full width at half maximum at 122 keV for a Cobalt-57 isotope source. By using IC circuits and using only a single 12 volt supply and ground, the novel amplifier provides significant power savings and is well suited for prolonged portable in-field use and does not require heavy, bulky power supply components.

  2. Electrical delay line multiplexing for pulsed mode radiation detectors

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    Medical imaging systems are composed of a large number of position sensitive radiation detectors to provide high resolution imaging. For example, whole-body Positron Emission Tomography (PET) systems are typically composed of thousands of scintillation crystal elements, which are coupled to photosensors. Thus, PET systems greatly benefit from methods to reduce the number of data acquisition channels, in order to reduce the system development cost and complexity. In this paper we present an electrical delay line multiplexing scheme that can significantly reduce the number of readout channels, while preserving the signal integrity required for good time resolution performance. We experimented with two 4 × 4 LYSO crystal arrays, with crystal elements having 3 mm × 3 mm × 5 mm and 3 mm × 3 mm × 20 mm dimensions, coupled to 16 Hamamatsu MPPC S10931-050P SiPM elements. Results show that each crystal could be accurately identified, even in the presence of scintillation light sharing and inter-crystal Compton scatter among neighboring crystal elements. The multiplexing configuration degraded the coincidence timing resolution from ?243 ps FWHM to ?272 ps FWHM when 16 SiPM signals were combined into a single channel for the 4 × 4 LYSO crystal array with 3 mm × 3 mm × 20 mm crystal element dimensions, in coincidence with a 3 mm × 3 mm × 5 mm LYSO crystal pixel. The method is flexible to allow multiplexing configurations across different block detectors, and is scalable to an entire ring of detectors.

  3. Ambient temperature cadmium zinc telluride radiation detector and amplifier circuit

    DOEpatents

    McQuaid, J.H.; Lavietes, A.D.

    1998-05-26

    A low noise, low power consumption, compact, ambient temperature signal amplifier for a Cadmium Zinc Telluride (CZT) radiation detector is disclosed. The amplifier can be used within a larger system (e.g., including a multi-channel analyzer) to allow isotopic analysis of radionuclides in the field. In one embodiment, the circuit stages of the low power, low noise amplifier are constructed using integrated circuit (IC) amplifiers , rather than discrete components, and include a very low noise, high gain, high bandwidth dual part preamplification stage, an amplification stage, and an filter stage. The low noise, low power consumption, compact, ambient temperature amplifier enables the CZT detector to achieve both the efficiency required to determine the presence of radionuclides and the resolution necessary to perform isotopic analysis to perform nuclear material identification. The present low noise, low power, compact, ambient temperature amplifier enables a CZT detector to achieve resolution of less than 3% full width at half maximum at 122 keV for a Cobalt-57 isotope source. By using IC circuits and using only a single 12 volt supply and ground, the novel amplifier provides significant power savings and is well suited for prolonged portable in-field use and does not require heavy, bulky power supply components. 9 figs.

  4. Large area radiation detectors based on II VI thin films

    NASA Astrophysics Data System (ADS)

    Quevedo-Lopez, Manuel

    2015-03-01

    The development of low temperature device technologies that have enabled flexible displays also present opportunities for flexible electronics and flexible integrated systems. Of particular interest are possible applications in flexible, low metal content, sensor systems for unattended ground sensors, smart medical bandages, electronic ID tags for geo-location, conformal antennas, neutron/gamma-ray/x-ray detectors, etc. In this talk, our efforts to develop novel CMOS integration schemes, circuits, memory, sensors as well as novel contacts, dielectrics and semiconductors for flexible electronics are presented. In particular, in this presentation we discuss fundamental materials properties including crystalline structure, interfacial reactions, doping, etc. defining performance and reliability of II-VI-based radiation sensors. We investigate the optimal thickness of a semiconductor diode for thin-film solid state thermal neutron detectors. Besides II-VI materials, we also evaluated several diode materials, Si, CdTe,GaAs, C (diamond), and ZnO, and two neutron converter materials,10B and 6LiF. We determine the minimum semiconductor thickness needed to achieve maximum neutron detection efficiency. By keeping the semiconductor thickness to a minimum, gamma rejection is kept as high as possible. In this way, we optimize detector performance for different thin-film semiconductor materials.

  5. Methodology for Assessing Radiation Detectors Used by Emergency Responders

    SciTech Connect

    Piotr Wasiolek; April Simpson

    2008-03-01

    The threat of weapons of mass destruction terrorism resulted in the U.S. Department of Homeland Security deploying large quantities of radiation detectors throughout the emergency responder community. However, emergency responders specific needs were not always met by standard health physics instrumentation used in radiation facilities. Several American National Standards Institute standards were developed and approved to evaluate the technical capabilities of detection equipment. Establishing technical capability is a critical step, but it is equally important to emergency responders that the instruments are easy to operate and can withstand the rugged situations they encounter. The System Assessment and Validation for Emergency Responders (SAVER) Program (managed by the U.S. Department of Homeland Security, Office of Grants and Training, Systems Support Division) focuses predominantly on the usability, ergonomics, readability, and other features of the detectors, rather than performance controlled by industry standards and the manufacturers. National Security Technologies, LLC, as a SAVER Technical Agent, conducts equipment evaluations using active emergency responders who are familiar with the detection equipment and knowledgeable of situations encountered in the field, which provides more relevant data to emergency responders.

  6. Laser system for testing radiation imaging detector circuits

    NASA Astrophysics Data System (ADS)

    Zubrzycka, Weronika; Kasinski, Krzysztof

    2015-09-01

    Performance and functionality of radiation imaging detector circuits in charge and position measurement systems need to meet tight requirements. It is therefore necessary to thoroughly test sensors as well as read-out electronics. The major disadvantages of using radioactive sources or particle beams for testing are high financial expenses and limited accessibility. As an alternative short pulses of well-focused laser beam are often used for preliminary tests. There are number of laser-based devices available on the market, but very often their applicability in this field is limited. This paper describes concept, design and validation of laser system for testing silicon sensor based radiation imaging detector circuits. The emphasis is put on keeping overall costs low while achieving all required goals: mobility, flexible parameters, remote control and possibility of carrying out automated tests. The main part of the developed device is an optical pick-up unit (OPU) used in optical disc drives. The hardware includes FPGA-controlled circuits for laser positioning in 2 dimensions (horizontal and vertical), precision timing (frequency and number) and amplitude (diode current) of short ns-scale (3.2 ns) light pulses. The system is controlled via USB interface by a dedicated LabVIEW-based application enabling full manual or semi-automated test procedures.

  7. Room temperature aluminum antimonide radiation detector and methods thereof

    SciTech Connect

    Lordi, Vincenzo; Wu, Kuang Jen J.; Aberg, Daniel; Erhart, Paul; Coombs, III, Arthur W; Sturm, Benjamin W

    2015-03-03

    In one embodiment, a method for producing a high-purity single crystal of aluminum antimonide (AlSb) includes providing a growing environment with which to grow a crystal, growing a single crystal of AlSb in the growing environment which comprises hydrogen (H.sub.2) gas to reduce oxide formation and subsequent incorporation of oxygen impurities in the crystal, and adding a controlled amount of at least one impurity to the growing environment to effectively incorporate at least one dopant into the crystal. In another embodiment, a high energy radiation detector includes a single high-purity crystal of AlSb, a supporting structure for the crystal, and logic for interpreting signals obtained from the crystal which is operable as a radiation detector at a temperature of about 25.degree. C. In one embodiment, a high-purity single crystal of AlSb includes AlSb and at least one dopant selected from a group consisting of selenium (Se), tellurium (Te), and tin (Sn).

  8. CMOS Imaging Detectors as X-ray Detectors for Synchrotron Radiation Experiments

    SciTech Connect

    Yagi, Naoto; Uesugi, Kentaro; Inoue, Katsuaki

    2004-05-12

    CMOS imagers are matrix-addressed photodiode arrays, which have been utilized in devices such as commercially available digital cameras. The pixel size of CMOS imagers is usually larger than that of CCD and smaller than that of TFT, giving them a unique position. Although CMOS x-ray imaging devices have already become commercially available, they have not been used as an x-ray area detector in synchrotron radiation experiments. We tested performance of a CMOS detector from Rad-icon (Shad-o-Box1024) in medical imaging, small-angle scattering, and protein crystallography experiments. It has pixels of 0.048 mm square, read-out time of 0.45 sec, 12-bit ADC, and requires a frame grabber for image acquisition. The detection area is 5-cm square. It uses a Kodak Min-R scintillator screen as a phosphor. The sensitivity to x-rays with an energy less than 15 keV was low because of the thick window materials. Since the readout noise is high, the dynamic range is limited to 2000. The biggest advantages of this detector are cost-effectiveness (about 10,000 US dollars) and compactness (thickness < 3 cm, weight < 2 kg)

  9. Field Deployable Gamma Radiation Detectors for DHS Use

    SciTech Connect

    Sanjoy Mukhopadhyay

    2007-08-01

    Recently, the Department of Homeland Security (DHS) has integrated all nuclear detection research, development, testing, evaluation, acquisition, and operational support into a single office: the Domestic Nuclear Detection Office (DNDO). The DNDO has specific requirements set for all commercial off-the-shelf and government off-the-shelf radiation detection equipment and data acquisition systems. This article would investigate several recent developments in field deployable gamma radiation detectors that are attempting to meet the DNDO specifications. Commercially available, transportable, handheld radio isotope identification devices (RIID) are inadequate for DHS requirements in terms of sensitivity, resolution, response time, and reach-back capability. The leading commercial vendor manufacturing handheld gamma spectrometer in the United States is Thermo Electron Corporation. Thermo Electron's identiFINDER{trademark}, which primarily uses sodium iodide crystals (3.18 x 2.54cm cylinders) as gamma detectors, has a Full-Width-at-Half-Maximum energy resolution of 7 percent at 662 keV. Thermo Electron has just recently come up with a reach-back capability patented as RadReachBack{trademark} that enables emergency personnel to obtain real-time technical analysis of radiation samples they find in the field. The current project has the goal to build a prototype handheld gamma spectrometer, equipped with a digital camera and an embedded cell phone to be used as an RIID with higher sensitivity, better resolution, and faster response time (able to detect the presence of gamma-emitting radio isotopes within 5 seconds of approach), which will make it useful as a field deployable tool. The handheld equipment continuously monitors the ambient gamma radiation, and, if it comes across any radiation anomalies with higher than normal gamma gross counts, it sets an alarm condition. When a substantial alarm level is reached, the system automatically triggers the saving of relevant spectral data and software-triggers the digital camera to take a snapshot. The spectral data including in situ analysis and the imagery data will be packaged in a suitable format and sent to a command post using an imbedded cell phone.

  10. Field Deployable Gamma Radiation Detectors for DHS Use

    SciTech Connect

    Sanjoy Mukhopadhyay

    2007-08-31

    Recently, the U.S. Department of Homeland Security (DHS) has integrated all nuclear detection research, development, testing, evaluation, acquisition, and operational support into a single office: the Domestic Nuclear Detection Office (DNDO). The DNDO has specific requirements set for all commercial and government off-the-shelf radiation detection equipment and data acquisition systems. This article would investigate several recent developments in field deployable gamma radiation detectors that are attempting to meet the DNDO specifications. Commercially available, transportable, handheld radio isotope identification devices (RIID) are inadequate for DHS’s requirements in terms of sensitivity, resolution, response time and reach back capability. The leading commercial vendor manufacturing handheld gamma spectrometer in the United States is Thermo Electron Corporation. Thermo Electron’s identiFINDER™, which primarily uses sodium iodide crystals (3.18-cm x 2.54-cm cylinders) as gamma detector, has a Full-Width-at-Half-Maximum energy resolution of 7 percent at 662 keV. Thermo Electron has just recently come up with a reach-back capability patented as RadReachBack™ that enables emergency personnel to obtain real-time technical analysis of radiation samples they find in the field. The current project has the goal to build a prototype handheld gamma spectrometer, equipped with a digital camera and an embedded cell phone to be used as an RIID with higher sensitivity (comparable to that of a 7.62-cm x 7.62-cm sodium iodide crystal at low gamma energy ranging from 30 keV to 3,000 keV), better resolution (< 3.0 percent at 662 keV), faster response time (able to detect the presence of gamma-emitting radio isotopes within 5 seconds of approach), which will make it useful as a field deployable tool. The handheld equipment continuously monitors the ambient gamma radiation and, if it comes across any radiation anomalies with higher than normal gamma gross counts, it sets an alarm condition. When a substantial alarm level is reached, the system auto triggers saving of relevant spectral data and software-triggers the digital camera to take a snapshot. The spectral data including in situ analysis and the imagery data will be packaged in a suitable format and sent to a command post using an imbedded cell phone.

  11. Advanced radiation detector development: Advanced semiconductor detector development: Development of a oom-temperature, gamma ray detector using gallium arsenide to develop an electrode detector

    SciTech Connect

    Knoll, G.F.

    1995-11-01

    The advanced detector development project at the University of Michigan has completed the first full year of its current funding. Our general goals are the development of radiation detectors and spectrometers that are capable of portable room temperature operation. Over the past 12 months, we have worked primarily in the development of semiconductor spectrometers with {open_quotes}single carrier{close_quotes} response that offer the promise of room temperature operation and good energy resolution in gamma ray spectroscopy. We have also begun a small scale effort at investigating the properties of a small non-spectroscopic detector system with directional characteristics that will allow identification of the approximate direction in which gamma rays are incident. These activities have made use of the extensive clean room facilities at the University of Michigan for semiconductor device fabrication, and also the radiation measurement capabilities provided in our laboratory in the Phoenix Building on the North Campus. In addition to our laboratory based activities, Professor Knoll has also been a participant in several Department of Energy review activities held in the Forrestal Building and at the Germantown site. The most recent of these has been service on a DOE review panel chaired by Dr. Hap Lamonds that is reviewing the detector development programs supported through the Office of Arms Control and International Security.

  12. Examination system utilizing ionizing radiation and a flexible, miniature radiation detector probe

    DOEpatents

    Majewski, Stanislaw (Grafton, VA); Kross, Brian J. (Yorktown, VA); Zorn, Carl J. (Yorktown, VA); Majewski, Lukasz A. (Grafton, VA)

    1996-01-01

    An optimized examination system and method based on the Reverse Geometry X-Ray.RTM. (RGX.RTM.) radiography technique are presented. The examination system comprises a radiation source, at least one flexible, miniature radiation detector probe positioned in appropriate proximity to the object to be examined and to the radiation source with the object located between the source and the probe, a photodetector device attachable to an end of the miniature radiation probe, and a control unit integrated with a display device connected to the photodetector device. The miniature radiation detector probe comprises a scintillation element, a flexible light guide having a first end optically coupled to the scintillation element and having a second end attachable to the photodetector device, and an opaque, environmentally-resistant sheath surrounding the flexible light guide. The probe may be portable and insertable, or may be fixed in place within the object to be examined. An enclosed, flexible, liquid light guide is also presented, which comprises a thin-walled flexible tube, a liquid, preferably mineral oil, contained within the tube, a scintillation element located at a first end of the tube, closures located at both ends of the tube, and an opaque, environmentally-resistant sheath surrounding the flexible tube. The examination system and method have applications in non-destructive material testing for voids, cracks, and corrosion, and may be used in areas containing hazardous materials. In addition, the system and method have applications for medical and dental imaging.

  13. Examination system utilizing ionizing radiation and a flexible, miniature radiation detector probe

    DOEpatents

    Majewski, S.; Kross, B.J.; Zorn, C.J.; Majewski, L.A.

    1996-10-22

    An optimized examination system and method based on the Reverse Geometry X-Ray{trademark} (RGX{trademark}) radiography technique are presented. The examination system comprises a radiation source, at least one flexible, miniature radiation detector probe positioned in appropriate proximity to the object to be examined and to the radiation source with the object located between the source and the probe, a photodetector device attachable to an end of the miniature radiation probe, and a control unit integrated with a display device connected to the photodetector device. The miniature radiation detector probe comprises a scintillation element, a flexible light guide having a first end optically coupled to the scintillation element and having a second end attachable to the photodetector device, and an opaque, environmentally-resistant sheath surrounding the flexible light guide. The probe may be portable and insertable, or may be fixed in place within the object to be examined. An enclosed, flexible, liquid light guide is also presented, which comprises a thin-walled flexible tube, a liquid, preferably mineral oil, contained within the tube, a scintillation element located at a first end of the tube, closures located at both ends of the tube, and an opaque, environmentally-resistant sheath surrounding the flexible tube. The examination system and method have applications in non-destructive material testing for voids, cracks, and corrosion, and may be used in areas containing hazardous materials. In addition, the system and method have applications for medical and dental imaging. 5 figs.

  14. Multiple cell radiation detector system, and method, and submersible sonde

    DOEpatents

    Johnson, Larry O. (Island Park, ID); McIsaac, Charles V. (Idaho Falls, ID); Lawrence, Robert S. (Shelley, ID); Grafwallner, Ervin G. (Arco, ID)

    2002-01-01

    A multiple cell radiation detector includes a central cell having a first cylindrical wall providing a stopping power less than an upper threshold; an anode wire suspended along a cylindrical axis of the central cell; a second cell having a second cylindrical wall providing a stopping power greater than a lower threshold, the second cylindrical wall being mounted coaxially outside of the first cylindrical wall; a first end cap forming a gas-tight seal at first ends of the first and second cylindrical walls; a second end cap forming a gas-tight seal at second ends of the first and second cylindrical walls; and a first group of anode wires suspended between the first and second cylindrical walls.

  15. BOBCAT Personal Radiation Detector Field Test and Evaluation Campaign

    SciTech Connect

    Chris Hodge

    2008-03-01

    Following the success of the Anole test of portable detection system, the U.S. Department of Homeland Security (DHS) Domestic Nuclear Detection Office organized a test and evaluation campaign for personal radiation detectors (PRDs), also known as “Pagers.” This test, “Bobcat,” was conducted from July 17 to August 8, 2006, at the Nevada Test Site. The Bobcat test was designed to evaluate the performance of PRDs under various operational scenarios, such as pedestrian surveying, mobile surveying, cargo container screening, and pedestrian chokepoint monitoring. Under these testing scenarios, many operational characteristics of the PRDs, such as gamma and neutron sensitivities, positive detection and false alarm rates, response delay times, minimum detectable activities, and source localization errors, were analyzed. This paper will present the design, execution, and methodologies used to test this equipment for the DHS.

  16. Personal Radiation Detector Field Test and Evaluation Campaign

    SciTech Connect

    Chris A. Hodge, Ding Yuan, Raymond P. Keegan, Michael A. Krstich

    2007-07-09

    Following the success of the Anole test of portable detection system, the U.S. Department of Homeland Security (DHS) Domestic Nuclear Detection Office organized a test and evaluation campaign for personal radiation detectors (PRDs), also known as 'Pagers'. This test, 'Bobcat', was conducted from July 17 to August 8, 2006, at the Nevada Test Site. The Bobcat test was designed to evaluate the performance of PRDs under various operational scenarios, such as pedestrian surveying, mobile surveying, cargo container screening, and pedestrian chokepoint monitoring. Under these testing scenarios, many operational characteristics of the PRDs, such as gamma and neutron sensitivities, positive detection and false alarm rates, response delay times, minimum detectable activities, and source localization errors, were analyzed. This paper will present the design, execution, and methodologies used to test this equipment for the DHS.

  17. Subnanosecond ellipticity detector for laser radiation S. D. Ganichev,a

    E-print Network

    Ganichev, Sergey

    elements, which allow the determi- nation of the optical path difference. Some tasks need mea- surement- biased semiconductor detector elements in response to laser radiation. The first element provides of the azimuth angle. The third detector element is a photon drag detector made of bulk germanium.1 It provides

  18. Improved gas mixtures for gas-filled radiation detectors

    DOEpatents

    Christophorou, L.G.; McCorkle, D.L.; Maxey, D.V.; Carter, J.G.

    1980-03-28

    Improved binary and ternary gas mixtures for gas-filled radiation detectors are provided. The components are chosen on the basis of the principle that the first component is one molecular gas or mixture of two molecular gases having a large electron scattering cross section at energies of about 0.5 eV and higher, and the second component is a noble gas having a very small cross section at and below about 1.0 eV, whereby fast electrons in the gaseous mixture are slowed into the energy range of about 0.5 eV where the cross section for the mixture is small and hence the electron mean free path is large. The reduction in both the cross section and the electron energy results in an increase in the drift velocity of the electrons in the gas mixtures over that for the separate components for a range of E/P (pressure-reduced electric field) values. Several gas mixtures are provided that provide faster response in gas-filled detectors for convenient E/P ranges as compared with conventional gas mixtures.

  19. Performance characteristics of a silicon photomultiplier based compact radiation detector for Homeland Security applications

    NASA Astrophysics Data System (ADS)

    Park, Hye Min; Joo, Koan Sik

    2015-05-01

    A next-generation compact radiation detector was studied for more accurate measurement of radiation and for improvement of detector reliability for the purpose of developing radiation protection technology and military applications. The previously used radiation detector had some limitations due to its bulky size, limited range and its environment for radiation measurement. On the other hand, the compact radiation detector examined in this study utilizes a silicon photomultiplier which appears to be more suitable for this application because of its physical superiority characterized by its small size, high sensitivity, and durability. Accordingly, a SiPM based scintillation detector has been developed as part of this basic study of military radiation detectors. The detector has been tested for its ability to obtain the operating characteristics of a sensor and analyzed with variations of parameter values and for efficiency of detection in accordance with its ability to measure radiation in the environment. Two SiPM based Scintillation detectors with LYSO, BGO and CsI:Tl scintillators were developed and the detectors were analyzed by a number of operating characteristics such as reverse bias, operating temperature and high magnetic field, that depend on environmental changes in radiation measurement. The Photon count rate and spectra were compared for these three scintillators. We found that there were variations in the radiation detection which were characterized by reverse bias, temperature and high magnetic field. It was also found that there was an 11.9% energy resolution for the LYSO, 15.5% for BGO and 13.5% for CsI:Tl using Array SiPM, and 18% for CsI:Tl energy resolution using single SiPM when we measured energy resolution of 511 keV for 22Na. These results demonstrate the potential widespread use of SiPM based compact radiation detectors for Homeland Security applications.

  20. Wire-chamber radiation detector with discharge control

    DOEpatents

    Perez-Mendez, V.; Mulera, T.A.

    1982-03-29

    A wire chamber; radiation detector has spaced apart parallel electrodes and grids defining an ignition region in which charged particles or other ionizing radiations initiate brief localized avalanche discharges and defining an adjacent memory region in which sustained glow discharges are initiated by the primary discharges. Conductors of the grids at each side of the memory section extend in orthogonal directions enabling readout of the X-Y coordinates of locations at which charged particles were detected by sequentially transmitting pulses to the conductors of one grid while detecting transmissions of the pulses to the orthogonal conductors of the other grid through glow discharges. One of the grids bounding the memory region is defined by an array of conductive elements each of which is connected to the associated readout conductor through a separate resistance. The wire chamber avoids ambiguities and imprecisions in the readout of coordinates when large numbers of simultaneous or; near simultaneous charged particles have been detected. Down time between detection periods and the generation of radio frequency noise are also reduced.

  1. Performance of bulk SiC radiation detectors

    NASA Astrophysics Data System (ADS)

    Cunningham, W.; Gouldwell, A.; Lamb, G.; Scott, J.; Mathieson, K.; Roy, P.; Bates, R.; Thornton, P.; Smith, K. M.; Cusco, R.; Glaser, M.; Rahman, M.

    2002-07-01

    SiC is a wide-gap material with excellent electrical and physical properties that may make it an important material for some future electronic devices. The most important possible applications of SiC are in hostile environments, such as in car/jet engines, within nuclear reactors, or in outer space. Another area where the material properties, most notably radiation hardness, would be valuable is in the inner tracking detectors of particle physics experiments. Here, we describe the performance of SiC diodes irradiated in the 24 GeV proton beam at CERN. Schottky measurements have been used to probe the irradiated material for changes in I- V characteristics. Other methods, borrowed from III-V research, used to study the irradiated surface include atomic force microscope scans and Raman spectroscopy. These have been used to observe the damage to the materials surface and internal lattice structure. We have also characterised the detection capabilities of bulk semi-insulating SiC for ? radiation. By measuring the charge collection efficiency (CCE) for variations in bias voltage, CCE values up to 100% have been measured.

  2. Method and system for determining depth distribution of radiation-emitting material located in a source medium and radiation detector system for use therein

    DOEpatents

    Benke, Roland R.; Kearfott, Kimberlee J.; McGregor, Douglas S.

    2004-04-27

    A radiation detector system includes detectors having different properties (sensitivity, energy resolution) which are combined so that excellent spectral information may be obtained along with good determinations of the radiation field as a function of position.

  3. Operation and radiation resistance of a FOXFET biasing structure for silicon strip detectors

    NASA Astrophysics Data System (ADS)

    Laakso, M.; Singh, P.; Engels, E., Jr.; Shepard, P.

    1992-02-01

    AC-coupled strip detectors biased with a FOXFET transistor structure were studied. Measurement results for the basic operational characteristics of the FOXFET are presented together with a brief description of the physics underlying its operation. Radiation effects were studied using photons from a Cs-137 source. Changes in the FOXFET characteristics as a function of radiation dose up to 1 MRad are reported. Results about the effect of radiation on the noise from a FOXFET biased detector are described.

  4. Plural-wavelength flame detector that discriminates between direct and reflected radiation

    NASA Technical Reports Server (NTRS)

    Hall, Gregory H. (Inventor); Barnes, Heidi L. (Inventor); Medelius, Pedro J. (Inventor); Simpson, Howard J. (Inventor); Smith, Harvey S. (Inventor)

    1997-01-01

    A flame detector employs a plurality of wavelength selective radiation detectors and a digital signal processor programmed to analyze each of the detector signals, and determine whether radiation is received directly from a small flame source that warrants generation of an alarm. The processor's algorithm employs a normalized cross-correlation analysis of the detector signals to discriminate between radiation received directly from a flame and radiation received from a reflection of a flame to insure that reflections will not trigger an alarm. In addition, the algorithm employs a Fast Fourier Transform (FFT) frequency spectrum analysis of one of the detector signals to discriminate between flames of different sizes. In a specific application, the detector incorporates two infrared (IR) detectors and one ultraviolet (UV) detector for discriminating between a directly sensed small hydrogen flame, and reflections from a large hydrogen flame. The signals generated by each of the detectors are sampled and digitized for analysis by the digital signal processor, preferably 250 times a second. A sliding time window of approximately 30 seconds of detector data is created using FIFO memories.

  5. Performance of an LPD prototype detector at MHz frame rates under Synchrotron and FEL radiation

    NASA Astrophysics Data System (ADS)

    Koch, A.; Hart, M.; Nicholls, T.; Angelsen, C.; Coughlan, J.; French, M.; Hauf, S.; Kuster, M.; Sztuk-Dambietz, J.; Turcato, M.; Carini, G. A.; Chollet, M.; Herrmann, S. C.; Lemke, H. T.; Nelson, S.; Song, S.; Weaver, M.; Zhu, D.; Meents, A.; Fischer, P.

    2013-11-01

    A MHz frame rate X-ray area detector (LPD — Large Pixel Detector) is under development by the Rutherford Appleton Laboratory for the European XFEL. The detector will have 1 million pixels and allows analogue storage of 512 images taken at 4.5 MHz in the detector front end. The LPD detector has 500 ?m thick silicon sensor tiles that are bump bonded to a readout ASIC. The ASIC's preamplifier provides relatively low noise at high speed which results in a high dynamic range of 105 photons over an energy range of 5-20 keV. Small scale prototypes of 32 × 256 pixels (LPD 2-Tile detector) and 256 × 256 pixels (LPD supermodule detector) are now available for X-ray tests. The performance of prototypes of the detector is reported for first tests under synchrotron radiation (PETRA III at DESY) and Free-Electron-Laser radiation (LCLS at SLAC). The initial performance of the detector in terms of signal range and noise, radiation hardness and spatial and temporal response are reported. The main result is that the 4.5 MHz sampling detection chain is reliably working, including the analogue on-chip memory concept. The detector is at least radiation hard up to 5 MGy at 12 keV. In addition the multiple gain concept has been demonstrated over a dynamic range to 104 at 12 keV with a readout noise equivalent to < 1 photon rms in its most sensitive mode.

  6. Ion Microbeam Studies of Cadmium Zinc Telluride Radiation Detectors by IBICC

    SciTech Connect

    Brunett, B.A.; Doyle, B.L.; James, R.B.; Olsen, R.W.; Vizkelethy, G.; Walsh, D.S.

    1998-10-26

    Ion Beam Induced Charge Collection (IBICC) and Time Resolved IBICC (TRIBICC) techniques were e for imaging electronic properties of Cadmium Zinc Telluride (CZT) room temperature radiation detectors. The detectors were bombarded with a scanned 5.4 MeV He microbeam and the detector response was analyzed at each point. The electron mobility (A) and Metime (z.), and charge collection efficiency maps were calculated from the data. In order to determine the radiation damage to the detectors, the signal deteriomtion was measured as the function of dose.

  7. Spacecraft Doppler tracking as a xylophone detector of gravitational radiation

    NASA Astrophysics Data System (ADS)

    Tinto, Massimo

    1996-05-01

    We discuss spacecraft Doppler tracking for detecting gravitational waves in which Doppler data recorded on the ground are linearly combined with Doppler measurements made on board a spacecraft. By using the four-link radio system first proposed by Vessot and Levine, we derive a new method for removing from the combined data the frequency fluctuations due to the Earth troposphere, ionosphere, and mechanical vibrations of the antenna on the ground. This method also reduces the frequency fluctuations of the clock on board the spacecraft by several orders of magnitude at selected Fourier components. The nonzero gravitational wave signal remaining at these frequencies makes this Doppler tracking technique the equivalent of a xylophone detector of gravitational radiation. In the assumption of calibrating the frequency fluctuations induced by the interplanetary plasma, a strain sensitivity equal to 4.7×10-18 at 10-3 Hz is estimated. Experiments of this kind could be performed (at minimal additional cost) with future interplanetary missions by adding instrumentation to the spacecraft payload and the ground station.

  8. Charged Particle Induced Radiation damage of Germanium Detectors in Space: Two Mars Observer Gamma-Ray Detectors

    NASA Technical Reports Server (NTRS)

    Bruekner, J.; Koenen, M.; Evans, L. G.; Starr, R.; Bailey, S. H.; Boynton W. V.

    1997-01-01

    The Mars Observer Gamma-Ray Spectrometer (MO GRS) was designed to measure gamma-rays emitted by the Martian surface. This gamma-ray emission is induced by energetic cosmic-ray particles penetrating the Martian surface and producing many secondary particles and gamma rays. The MO GRS consisted of an high-purity germanium (HPGe) detector with a passive cooler. Since radiation damage due to permanent bombardment of energetic cosmic ray particles (with energies up to several GeV) was expected for the MO GRS HPGe crystal, studies on radiation damage effects of HPGe crystals were carried on earth. One of the HPGe crystals (paradoxically called FLIGHT) was similar to the MO GRS crystal. Both detectors, MO GRS and FLIGHT, contained closed-end coaxial n-type HPGe crystals and had the same geometrical dimensions (5.6 x 5.6 cm). Many other parameters, such as HV and operation temperature, differed in space and on earth, which made it somewhat difficult to directly compare the performance of both detector systems. But among other detectors, detector FLIGHT provided many useful data to better understand radiation damage effects.

  9. Dynamic Electrothermal Model of a Sputtered Thermopile Thermal Radiation Detector for Earth Radiation Budget Applications

    NASA Technical Reports Server (NTRS)

    Weckmann, Stephanie

    1997-01-01

    The Clouds and the Earth's Radiant Energy System (CERES) is a program sponsored by the National Aeronautics and Space Administration (NASA) aimed at evaluating the global energy balance. Current scanning radiometers used for CERES consist of thin-film thermistor bolometers viewing the Earth through a Cassegrain telescope. The Thermal Radiation Group, a laboratory in the Department of Mechanical Engineering at Virginia Polytechnic Institute and State University, is currently studying a new sensor concept to replace the current bolometer: a thermopile thermal radiation detector. This next-generation detector would consist of a thermal sensor array made of thermocouple junction pairs, or thermopiles. The objective of the current research is to perform a thermal analysis of the thermopile. Numerical thermal models are particularly suited to solve problems for which temperature is the dominant mechanism of the operation of the device (through the thermoelectric effect), as well as for complex geometries composed of numerous different materials. Feasibility and design specifications are studied by developing a dynamic electrothermal model of the thermopile using the finite element method. A commercial finite element-modeling package, ALGOR, is used.

  10. Physica B 280 (2000) 532}534 Radiation hard position-sensitive cryogenic silicon detectors

    E-print Network

    Zavrtanik, Marko

    2000-01-01

    Physica B 280 (2000) 532}534 Radiation hard position-sensitive cryogenic silicon detectors-trapping processes severely a!ects the CCE mechanism. When the devices are operated below 130 K, the de-trapping time

  11. Terahertz spectroscopy with a holographic Fourier transform spectrometer plus array detector using coherent synchrotron radiation

    SciTech Connect

    Nikolay I. Agladz, John Klopf, Gwyn Williams, Albert J. Sievers

    2010-06-01

    By use of coherent terahertz synchrotron radiation, we experimentally tested a holographic Fourier transform spectrometer coupled to an array detector to determine its viability as a spectral device. Somewhat surprisingly, the overall performance strongly depends on the absorptivity of the birefringent lithium tantalate pixels in the array detector.

  12. Radiation detection system using semiconductor detector with differential carrier trapping and mobility

    DOEpatents

    Whited, Richard C. (Santa Barbara, CA)

    1981-01-01

    A system for obtaining improved resolution in relatively thick semiconductor radiation detectors, such as HgI.sub.2, which exhibit significant hole trapping. Two amplifiers are used: the first measures the charge collected and the second the contribution of the electrons to the charge collected. The outputs of the two amplifiers are utilized to unfold the total charge generated within the detector in response to a radiation event.

  13. Investigations of solar radiation detectors using a laboratory test facility for solar radiation meterological instruments

    SciTech Connect

    Philipona, R.; Heimo, A.; Hoegger, B. )

    1993-08-01

    A laboratory test facility for solar radiation detectors has been built and is in operation at the Aerological Station of the Swiss Meterological Institute (SAP/SMI) This installation is conceived as a universal test bed for solar radiation exposed meterological instruments, and consists of a commercially available solar simulator, a laser alignment system, a translation mechanism with instrument mounts, and an adjustable projection mirror. The solar simulator produces a well characterized radiation beam which can be filtered to match the terrestrial or outer space solar spectrum with an irradiance of up to one solar constant (1367 Wm[sup [minus]2]). The instrument mounts and a HeNe laser beam provide a precise and easy alignment of the reference and the test instruments in the radiation beam, allowing for incident angles in the range of 15[degrees]-75[degrees]. The measurement is based on a comparison of the response of an active cavity absolute radiometer PMO6 with the signal of the test instrument. Detailed investigations of the Haenni Solar 111B type heliometer have revealed important irregularities in the sunshine threshold irradiance angular distribution. Measurements performed with and without the protection glass cover prove the exceedingly high threshold values at large declination angles to be a consequence of enhanced reflections due to the incident angle and inhomogeneities in the glass cover. Very satisfactory results have also been obtained on characterization measurements of pyranometers showing the mean values of the responsivity to be within 0.8% of the calibration values measured at the world radiation center(WRC) at Davos.

  14. Characterizing the radiation response of Cherenkov glass detectors with isotopic sources

    SciTech Connect

    Hayward, J P; Hobbs, C. L.; Bell, Zane W; Boatner, Lynn A; Johnson, Rose E; Ramey, Joanne Oxendine; Jellison Jr, Gerald Earle; Lillard, Cole R; Ramey, Lucas A

    2012-01-01

    Abstract Cherenkov detectors are widely used for particle identification and threshold detectors in high-energy physics. Glass Cherenkov detectors that are sensitive to beta emissions originating from neutron activation have been demonstrated recently as a potential replacement for activation foils. In this work, we set the groundwork to evaluate large Cherenkov glass detectors for sensitivity to MeV photons through first understanding the measured response of small Cherenkov glass detectors to isotopic gamma-ray sources. Counting and pulse height measurements are acquired with reflected glass Cherenkov detectors read out with a photomultiplier tube. Simulation was used to inform our understanding of the measured results. This simulation included radioactive source decay, radiation interaction, Cherenkov light generation, optical ray tracing, and photoelectron production. Implications for the use of Cherenkov glass detectors to measure low energy gammaray response are discussed.

  15. Terahertz and Infrared Uncooled Detector Based on a Microcantilever as a Radiation Pressure Sensor

    E-print Network

    Gennady P. Berman; Boris M. Chernobrod; Alan R. Bishop; Vyacheslav N. Gorshkov

    2007-03-05

    We consider a far infrared (terahertz), room-temperature detector based on a microcantilever sensor of the radiation pressure. This system has a significantly higher sensitivity than existing uncooled detectors in the far infrared (terahertz) spectral region. The significant enhancement of sensitivity is due the combination non-absorption detection method and high quality optical microcavity. Our theoretical analysis of the detector sensitivity and numerical simulations demonstrate that the narrowband heterodyne detector with the band width 30 MHz has a minimal measurable intensity by three orders of magnitude less than conventional uncooled detectors. In the case of the broadband detector, the noise equivalent temperature difference (NETD) is 7.6 mK, which is significantly smaller than for conventional uncooled thermal detectors.

  16. Diurnal Variations of Energetic Particle Radiation Dose Measured by the Mars Science Laboratory Radiation Assessment Detector

    NASA Astrophysics Data System (ADS)

    Rafkin, Scot; Zeitlin, Cary; Ehresmann, Bent; Köhler, Jan; Guo, Jingnan; Kahanpää, Henrik; Hassler, Don; -Gomez, Javier E.; Wimmer-Schweingruber, Robert; Brinza, David; Böttcher, Stephan; Böhm, Eckhard; Burmeister, Sonka; Martin, Cesar; Müller-Mellin, Robert; Appel, Jan; Posner, Arik; Reitz, Gunter; Kharytonov, Aliksandr; Cucinotta, Francis

    2013-04-01

    The Radiation Assessment Detector (RAD) on board the Mars Science Laboratory (MSL) rover Curiosity has collected data on the interplanetary radiation environment during cruise from Earth to Mars and at the surface of Mars since its landing in August 2012. RAD's particle detection capabilities are achieved with a solid-state detector (SSD) stack (A, B, C), a CsI(Tl) scintillator (D), and a plastic scintillator (E) for neutron detection. The D and E detectors are surrounded by an anticoincidence shield (F), also made of plastic scintillator. All scintillators are optically coupled to silicon diodes which convert scintillation light to electrons. RAD is capable of measuring both Galactic Cosmic Rays (GCRs) thought to be produced by supernovae outside the heliosphere and Solar Energetic Particles (SEPs). GCRs are relativistic particles (100 MeV/nuc to >10 GeV/nuc) composed of roughly 89% protons, 10% alpha particles (He), and 1% heavier nuclei [1]. Because of their high energies and continuous nature, GCRs are the dominant source of background radiation at the Martian surface, and are responsible for the production of secondary particles (notably neutrons) via complex interactions in the atmosphere and regolith. SEPs are produced by coronal mass ejections. These intermittent storms are most likely to occur near solar maximum and typical fluxes are dominated by protons with energies lower than 100 MeV/nuc. Unlike the GCR flux, the SEP flux can vary by five or more orders of magnitude over timescales of a day. Even under a constant flux of energetic particle radiation at the top of the atmosphere, the radiation dose at the surface should vary as a function of surface elevation [2]. This variation is directly related to the change in the shielding provided by the total atmospheric mass column, which is to a very good approximation directly related to surface pressure. Thus, the flux of primary energetic particles should increase with altitude, all other things being equal. At present, MSL has been at a nearly constant altitude of ~-4.4 km MOLA so that no elevation-induced changes are expected and none have been observed. However, any process that changes the column mass of atmosphere should change the dose at the surface. On Mars there are two major processes that substantially change column atmospheric mass. The first is the seasonal condensation cycle during which ~25% of the dominant atmospheric constituent (CO2) condenses onto the winter pole. This seasonal signal is very strong and has been observed by surface pressure measurements from the Viking Landers up through MSL [3,4]. The second major process is related to the thermal tide. The direct heating of the Martian atmosphere by the Sun produces global scale waves that redistribute mass [5]. The two most dominant tidal modes are the diurnal and semidiurnal tide. Together, the thermal tide can produce a variation of 10-15% over a Martian day (sol). Here, we report on the dose measured by the RAD E detector and the variation of this dose over the diurnal cycle. Further, we show that the variation in the E dose rate is very likely due to the variation of column mass, as measured by the pressure sensor on the Rover Environmental Monitoring Station (REMS), driven by the thermal tide. While changes in dose were expected from changes in altitude or season, the discovery of a diurnal variation was not anticipated, although it should have been reasonably expected in hindsight.

  17. Radiation Measurements in Cruise and on Mars by the MSL Radiation Assessment Detector

    NASA Astrophysics Data System (ADS)

    Zeitlin, C. J.; Hassler, D.; Wimmer-Schweingruber, R. F.; Appel, J. K.; Boehm, E.; Boettcher, S.; Brinza, D.; Burmeister, S.; Cucinotta, F.; Ehresmann, B.; Guo, J.; Kohler, J.; Lohf, H.; Martin, C.; Posner, A.; Rafkin, S. C.; Reitz, G.; Team, M.

    2013-12-01

    The Radiation Assessment Detector (RAD) is one of ten science instruments on the Curiosity rover. The RAD team's science objectives include the measurement of radiation dose (a purely physical quantity) and dose equivalent (a derived quantity that can be related to cancer risk) on the surface of Mars. In addition, RAD acquired data for most of the cruise to Mars, from Dec. 2011 through July 2012, providing a measurement of the radiation environment under conditions similar to those expected on a human trip to Mars or other deep space destinations. The dose and dose equivalent measurements made during cruise have been published, but are presented in more detail here. Rates measured in cruise are compared to similar measurements made during Curiosity's first 269 sols on the surface of Mars. In the simplest picture, one expects rates to be a factor of two lower on the surface of a large airless body compared to free space, owing to the two-pi shielding geometry. The situation on Mars is complicated by the non-negligible shielding effects of the atmosphere, particularly in Gale Crater where diurnal variations in atmospheric column depth are significant. The diurnal variations - caused by the well-known thermal tides on Mars - result in reduced shielding of the surface in the afternoon as compared to the night and early morning hours. A major challenge in analyzing the surface data is the treatment of the background radiation dose coming from Curiosity's Radioisotope Thermoelectric Generator (RTG). Prior to launch, RAD acquired data in the full cruise configuration so that this background could be measured with only sea-level cosmic ray muons present - that is, almost all of what was measured was due to the RTG. Those effects could therefore be subtracted from the cruise measurements in a straightforward way. However, the situation on the surface is somewhat different than in cruise, in that the mass that was present above RAD - and caused scattering of particles into the detector - is no longer there. The RTG-induced dose rate in the surface configuration must therefore be less than it was in the cruise configuration, but there is no way to get a direct measurement of the background. Quantifying the change in RTG background is difficult but essential, as the subtraction affects every aspect of the dosimetry. Two approaches have been developed and yield roughly similar results. The differences allow us to estimate the uncertainties arising from the RTG subtraction, and propagate those into the dosimetry results.

  18. DEVELOPMENT OF CdZnTe RADIATION DETECTORS

    SciTech Connect

    BOLOTNIKOV, A.; CAMARDA, G.; HOSSAIN, A.; KIM, K.H.; YANG, G.; GUL, R.; CUI, Y.; AND JAMES, R.B.

    2011-10-23

    Cadmium Zinc Telluride (CdZnTe or CZT) is a very attractive material for room-temperature semiconductor detectors because of its wide band-gap and high atomic number. Despite these advantages, CZT still presents some material limitations and poor hole mobility. In the past decade most of the developing CZT detectors focused on designing different electrode configurations, mainly to minimize the deleterious effect due to the poor hole mobility. A few different electrode geometries were designed and fabricated, such as pixelated anodes and Frisch-grid detectors developed at Brookhaven National Lab (BNL). However, crystal defects in CZT materials still limit the yield of detector-grade crystals, and, in general, dominate the detector's performance. In the past few years, our group's research extended to characterizing the CZT materials at the micro-scale, and to correlating crystal defects with the detector's performance. We built a set of unique tools for this purpose, including infrared (IR) transmission microscopy, X-ray micro-scale mapping using synchrotron light source, X-ray transmission- and reflection-topography, current deep level transient spectroscopy (I-DLTS), and photoluminescence measurements. Our most recent work on CZT detectors was directed towards detailing various crystal defects, studying the internal electrical field, and delineating the effects of thermal annealing on improving the material properties. In this paper, we report our most recent results.

  19. Methods for radiation detection and characterization using a multiple detector probe

    DOEpatents

    Akers, Douglas William; Roybal, Lyle Gene

    2014-11-04

    Apparatuses, methods, and systems relating to radiological characterization of environments are disclosed. Multi-detector probes with a plurality of detectors in a common housing may be used to substantially concurrently detect a plurality of different radiation activities and types. Multiple multi-detector probes may be used in a down-hole environment to substantially concurrently detect radioactive activity and contents of a buried waste container. Software may process, analyze, and integrate the data from the different multi-detector probes and the different detector types therein to provide source location and integrated analysis as to the source types and activity in the measured environment. Further, the integrated data may be used to compensate for differential density effects and the effects of radiation shielding materials within the volume being measured.

  20. Low radioactivity material for use in mounting radiation detectors

    NASA Technical Reports Server (NTRS)

    Fong, Marshall; Metzger, Albert E.; Fox, Richard L.

    1988-01-01

    Two materials, sapphire and synthetic quartz, have been found for use in Ge detector mounting assemblies. These materials combine desirable mechanical, thermal, and electrical properties with the radioactive cleanliness required to detect minimal amounts of K, Th, and U.

  1. Performance test of pipe-shaped radiation shields for cryogenic interferometric gravitational wave detectors

    NASA Astrophysics Data System (ADS)

    Sakakibara, Yusuke; Kimura, Nobuhiro; Akutsu, Tomotada; Suzuki, Toshikazu; Kuroda, Kazuaki

    2015-08-01

    One of the most important challenges in cryogenic interferometric gravitational wave detectors is to reduce the undesirable thermal radiation coming through holes in the radiation shield, which are necessary for the laser beam to pass through. For this purpose, pipe-shaped radiation shields called duct shields are used. Here, we have manufactured duct shields for KAGRA in Japan, one of the cryogenic interferometric gravitational wave detectors, and measured the thermal radiation coming through the duct shields. The measured result was found to be consistent with the calculation result that the duct shield can reduce the thermal radiation to less than 1%. This fact confirmed that the amount of thermal radiation coming through the duct shields was smaller than KAGRA’s requirement.

  2. Simulation of ion beam induced current in radiation detectors and microelectronic devices.

    SciTech Connect

    Vizkelethy, Gyorgy

    2009-10-01

    Ionizing radiation is known to cause Single Event Effects (SEE) in a variety of electronic devices. The mechanism that leads to these SEEs is current induced by the radiation in these devices. While this phenomenon is detrimental in ICs, this is the basic mechanism behind the operation of semiconductor radiation detectors. To be able to predict SEEs in ICs and detector responses we need to be able to simulate the radiation induced current as the function of time. There are analytical models, which work for very simple detector configurations, but fail for anything more complex. On the other end, TCAD programs can simulate this process in microelectronic devices, but these TCAD codes costs hundreds of thousands of dollars and they require huge computing resources. In addition, in certain cases they fail to predict the correct behavior. A simulation model based on the Gunn theorem was developed and used with the COMSOL Multiphysics framework.

  3. Diurnal Variations of Energetic Particle Radiation Dose Measured by the Mars Science Laboratory Radiation Assessment Detector

    NASA Astrophysics Data System (ADS)

    Rafkin, Scot

    The Radiation Assessment Detector (RAD) on board the Mars Science Laboratory (MSL) rover Curiosity has collected data on the interplanetary radiation environment during cruise from Earth to Mars and at the surface of Mars since its landing in August 2012. Any process that changes the column mass of atmosphere should change the dose at the surface due to the shielding effect of the atmosphere. On Mars there are two major processes that substantially change column atmospheric mass. The first is the seasonal condensation cycle during which 25% of the dominant atmospheric constituent (CO2) condenses onto the winter pole. The second major process is related to thermal tides forced by the direct heating of the Martian atmosphere by the Sun. The thermal tide can produce a column mass variation of 10-15% over a Martian day (sol). Here, we report on the total dose rate and neutral count rate measured by MSL RAD and the variation of these dose rates over the diurnal cycle. Further, we show that the variation in the dose rates is very likely due to the variation of column mass, as measured by the pressure sensor on the Rover Environmental Monitoring Station (REMS). While changes in dose were expected from changes in altitude or season, the discovery of a diurnal variation was not anticipated, although it should have been reasonably expected in hindsight.

  4. A program in detector development for the US synchrotron radiation community

    SciTech Connect

    Thompson, A.; Mills, D.; Naday, S.; Gruner, S.; Siddons, P.; Arthur, J.; Wehlitz, R.; Padmore, H.

    2001-07-14

    There is a clear gulf between the capabilities of modern synchrotrons to deliver high photon fluxes, and the capabilities of detectors to measure the resulting photon, electron or ion signals. While a huge investment has been made in storage ring technology, there has not to date been a commensurate investment in detector systems. With appropriate detector technology, gains in data rates could be 3 to 4 orders of magnitude in some cases. The US community working in detector technology is under-funded and fragmented and works without the long term funding commitment required for development of the most advanced detector systems. It is becoming apparent that the US is falling behind its international competitors in provision of state-of-the-art detector technology for cutting edge synchrotron radiation based experiments.

  5. LiF:Mg,Ti (MTT) TL detectors optimised for high-LET radiation dosimetry.

    PubMed

    Bilski, P; Budzanowski, M; Olko, P; Mandowska, E

    2004-01-01

    The properties of LiF:Mg,Ti (distributed as, e.g., TLD-100 or MTS-N), the most frequently used thermoluminescent detector, have been optimised for measurements of sparsely ionizing radiation (gamma rays), typically encountered in radiation protection or clinical dosimetry. However, these detectors need also to be applied in conditions of mixed-field dosimetry with a high-LET component, such as those encountered in heavy ion beams or in space. At the Institute of Nuclear Physics in Kraków a new type of LiF:Mg,Ti detector (named MTT) has been recently developed through modification of its dopant composition. This composition is intended to increase the detection efficiency after a dose of high-LET radiation. The concentration of dopants in the MTT material is: CMg=50 ppm, and CTi=120 ppm, i.e. about a three times less of magnesium and about 10 times more of titanium content, compared with the standard MTS-N. The MTT TL detectors feature an increased relative efficiency to high-LET radiation, which for 5 MeV alpha-particles is about twice that of standard LiF:Mg,Ti. The response of MTT detectors has been studied in charged particle beams of the HIMAC accelerator in Chiba, Japan and in Dubna, Russia. The main foreseen application of MTT detectors are dose measurements in space. The dose after high-LET exposure can be estimated from the difference of the response of MTS and MTT detectors. In the near future MTT detectors will be applied in the "Matroshka" experiment. Within this experiment a specially constructed human phantom will be exposed in free space (outside the International Space Station) for 1 year. The phantom will incorporate a few thousand measuring points enabling radiation doses to particular organs to be determined. PMID:15856580

  6. Electromagnetic and nuclear radiation detector using micromechanical sensors

    DOEpatents

    Thundat, Thomas G. (Knoxville, TN); Warmack, Robert J. (Knoxville, TN); Wachter, Eric A. (Oak Ridge, TN)

    2000-01-01

    Electromagnetic and nuclear radiation is detected by micromechanical sensors that can be coated with various interactive materials. As the micromechanical sensors absorb radiation, the sensors bend and/or undergo a shift in resonance characteristics. The bending and resonance changes are detected with high sensitivity by any of several detection methods including optical, capacitive, and piezoresistive methods. Wide bands of the electromagnetic spectrum can be imaged with picoJoule sensitivity, and specific absorptive coatings can be used for selective sensitivity in specific wavelength bands. Microcantilevers coated with optical cross-linking polymers are useful as integrating optical radiation dosimeters. Nuclear radiation dosimetry is possible by fabricating cantilevers from materials that are sensitive to various nuclear particles or radiation. Upon exposure to radiation, the cantilever bends due to stress and its resonance frequency shifts due to changes in elastic properties, based on cantilever shape and properties of the coating.

  7. Development of Semiconductor Detectors for Very Harsh Radiation Environments in High Energy Physics Applications

    NASA Astrophysics Data System (ADS)

    Casse, G.

    2004-08-01

    The Large Hadron Collider (LHC) at CERN has been designed to achieve the unprecedented luminosity of 1034 cm-2 s-1. As a consequence, the silicon detectors close to the interaction region will receive severe doses of hadron irradiation. The present sensors are designed to survive fast hadron fluences of about 1015 cm-2. Due to the anticipated radiation levels, the fluence expected at the innermost tracker detectors can already exceed this value before the end of the lifetime of the experiment, so that some experiments foresee to change these detectors after a few years of operation (e.g. LHCb VELO). Moreover, the option of increasing the luminosity of LHC to 1035 cm-2 s-1 has been envisaged to extend the physics reach of the machine. An efficient tracking down to a few centimetres from the interaction point will be required to exploit the physics potential of the upgraded LHC. Under these conditions, the inner tracker detectors will need to survive fast hadron fluences above 1016 cm-2. The CERN-RD50 project "Development of Radiation Hard Semiconductor Devices for Very High Luminosity Collider" has been set-up to explore detector technologies that will allow to operate devices up to, or beyond, this limit. The strategies followed by RD50 to enhance the radiation tolerance include the development of new or defect engineered detector materials (SiC, GaN, CZ and EPI silicon, oxygen enriched silicon), the evaluation of new detector designs (3D, Semi-3D detectors), the improvement of present detector designs and, on the fundamental semiconductor physics aspect, the understanding of the microscopic defects causing the degradation of the irradiated detectors. The latest advancements within the RD50 collaboration will be reviewed and discussed in this work.

  8. Radiation Hard AlGaN Detectors and Imager

    SciTech Connect

    2012-05-01

    Radiation hardness of AlGaN photodiodes was tested using a 65 MeV proton beam with a total proton fluence of 3x10{sup 12} protons/cm{sup 2}. AlGaN Deep UV Photodiode have extremely high radiation hardness. These new devices have mission critical applications in high energy density physics (HEDP) and space explorations. These new devices satisfy radiation hardness requirements by NIF. NSTec is developing next generation AlGaN optoelectronics and imagers.

  9. Technical Note: Response measurement for select radiation detectors in magnetic fields

    SciTech Connect

    Reynolds, M.; Fallone, B. G.; Rathee, S.

    2015-06-15

    Purpose: Dose response to applied magnetic fields for ion chambers and solid state detectors has been investigated previously for the anticipated use in linear accelerator–magnetic resonance devices. In this investigation, the authors present the measured response of selected radiation detectors when the magnetic field is applied in the same direction as the radiation beam, i.e., a longitudinal magnetic field, to verify previous simulation only data. Methods: The dose response of a PR06C ion chamber, PTW60003 diamond detector, and IBA PFD diode detector is measured in a longitudinal magnetic field. The detectors are irradiated with buildup caps and their long axes either parallel or perpendicular to the incident photon beam. In each case, the magnetic field dose response is reported as the ratio of detector signals with to that without an applied longitudinal magnetic field. The magnetic field dose response for each unique orientation as a function of magnetic field strength was then compared to the previous simulation only studies. Results: The measured dose response of each detector in longitudinal magnetic fields shows no discernable response up to near 0.21 T. This result was expected and matches the previously published simulation only results, showing no appreciable dose response with magnetic field. Conclusions: Low field longitudinal magnetic fields have been shown to have little or no effect on the dose response of the detectors investigated and further lend credibility to previous simulation only studies.

  10. Active noise canceling system for mechanically cooled germanium radiation detectors

    SciTech Connect

    Nelson, Karl Einar; Burks, Morgan T

    2014-04-22

    A microphonics noise cancellation system and method for improving the energy resolution for mechanically cooled high-purity Germanium (HPGe) detector systems. A classical adaptive noise canceling digital processing system using an adaptive predictor is used in an MCA to attenuate the microphonics noise source making the system more deployable.

  11. High field CdS detector for infrared radiation

    NASA Technical Reports Server (NTRS)

    Tyagi, R. C.; Boer, K. W.; Hadley, H. C.; Robertson, J. B.

    1972-01-01

    New and highly sensitive method of detecting infrared irradiation makes possible solid state infrared detector which is more sensitive near room temperature than usual photoconductive low band gap semiconductor devices. Reconfiguration of high field domains in cadmium sulphide crystals provides basis for discovery.

  12. Characterization of a novel two dimensional diode array the ''magic plate'' as a radiation detector for radiation therapy treatment

    SciTech Connect

    Wong, J. H. D.; Fuduli, I.; Carolan, M.; Petasecca, M.; Lerch, M. L. F.; Perevertaylo, V. L.; Metcalfe, P.; Rosenfeld, A. B.

    2012-05-15

    Purpose: Intensity modulated radiation therapy (IMRT) utilizes the technology of multileaf collimators to deliver highly modulated and complex radiation treatment. Dosimetric verification of the IMRT treatment requires the verification of the delivered dose distribution. Two dimensional ion chamber or diode arrays are gaining popularity as a dosimeter of choice due to their real time feedback compared to film dosimetry. This paper describes the characterization of a novel 2D diode array, which has been named the ''magic plate'' (MP). It was designed to function as a 2D transmission detector as well as a planar detector for dose distribution measurements in a solid water phantom for the dosimetric verification of IMRT treatment delivery. Methods: The prototype MP is an 11 x 11 detector array based on thin (50 {mu}m) epitaxial diode technology mounted on a 0.6 mm thick Kapton substrate using a proprietary ''drop-in'' technology developed by the Centre for Medical Radiation Physics, University of Wollongong. A full characterization of the detector was performed, including radiation damage study, dose per pulse effect, percent depth dose comparison with CC13 ion chamber and build up characteristics with a parallel plane ion chamber measurements, dose linearity, energy response and angular response. Results: Postirradiated magic plate diodes showed a reproducibility of 2.1%. The MP dose per pulse response decreased at higher dose rates while at lower dose rates the MP appears to be dose rate independent. The depth dose measurement of the MP agrees with ion chamber depth dose measurements to within 0.7% while dose linearity was excellent. MP showed angular response dependency due to the anisotropy of the silicon diode with the maximum variation in angular response of 10.8% at gantry angle 180 deg. Angular dependence was within 3.5% for the gantry angles {+-} 75 deg. The field size dependence of the MP at isocenter agrees with ion chamber measurement to within 1.1%. In the beam perturbation study, the surface dose increased by 12.1% for a 30 x 30 cm{sup 2} field size at the source to detector distance (SDD) of 80 cm whilst the transmission for the MP was 99%. Conclusions: The radiation response of the magic plate was successfully characterized. The array of epitaxial silicon based detectors with ''drop-in'' packaging showed properties suitable to be used as a simplified multipurpose and nonperturbing 2D radiation detector for radiation therapy dosimetric verification.

  13. A transition radiation detector for RHIC featuring accurate tracking and dE/dx particle identification

    SciTech Connect

    O`Brien, E.; Lissauer, D.; McCorkle, S.; Polychronakos, V.; Takai, H.; Chi, C.Y.; Nagamiya, S.; Sippach, W.; Toy, M.; Wang, D.; Wang, Y.F.; Wiggins, C.; Willis, W.; Cherniatin, V.; Dolgoshein, B.; Bennett, M.; Chikanian, A.; Kumar, S.; Mitchell, J.T.; Pope, K.

    1991-12-31

    We describe the results of a test ran involving a Transition Radiation Detector that can both distinguish electrons from pions which momenta greater titan 0.7 GeV/c and simultaneously track particles passing through the detector. The particle identification is accomplished through a combination of the detection of Transition Radiation from the electron and the differences in electron and pion energy loss (dE/dx) in the detector. The dE/dx particle separation is most, efficient below 2 GeV/c while particle ID utilizing Transition Radiation effective above 1.5 GeV/c. Combined, the electron-pion separation is-better than 5 {times} 10{sup 2}. The single-wire, track-position resolution for the TRD is {approximately}230 {mu}m.

  14. Review on the characteristics of radiation detectors for dosimetry and imaging

    NASA Astrophysics Data System (ADS)

    Seco, Joao; Clasie, Ben; Partridge, Mike

    2014-10-01

    The enormous advances in the understanding of human anatomy, physiology and pathology in recent decades have led to ever-improving methods of disease prevention, diagnosis and treatment. Many of these achievements have been enabled, at least in part, by advances in ionizing radiation detectors. Radiology has been transformed by the implementation of multi-slice CT and digital x-ray imaging systems, with silver halide films now largely obsolete for many applications. Nuclear medicine has benefited from more sensitive, faster and higher-resolution detectors delivering ever-higher SPECT and PET image quality. PET/MR systems have been enabled by the development of gamma ray detectors that can operate in high magnetic fields. These huge advances in imaging have enabled equally impressive steps forward in radiotherapy delivery accuracy, with 4DCT, PET and MRI routinely used in treatment planning and online image guidance provided by cone-beam CT. The challenge of ensuring safe, accurate and precise delivery of highly complex radiation fields has also both driven and benefited from advances in radiation detectors. Detector systems have been developed for the measurement of electron, intensity-modulated and modulated arc x-ray, proton and ion beams, and around brachytherapy sources based on a very wide range of technologies. The types of measurement performed are equally wide, encompassing commissioning and quality assurance, reference dosimetry, in vivo dosimetry and personal and environmental monitoring. In this article, we briefly introduce the general physical characteristics and properties that are commonly used to describe the behaviour and performance of both discrete and imaging detectors. The physical principles of operation of calorimeters; ionization and charge detectors; semiconductor, luminescent, scintillating and chemical detectors; and radiochromic and radiographic films are then reviewed and their principle applications discussed. Finally, a general discussion of the application of detectors for x-ray nuclear medicine and ion beam imaging and dosimetry is presented.

  15. Review on the characteristics of radiation detectors for dosimetry and imaging.

    PubMed

    Seco, Joao; Clasie, Ben; Partridge, Mike

    2014-10-21

    The enormous advances in the understanding of human anatomy, physiology and pathology in recent decades have led to ever-improving methods of disease prevention, diagnosis and treatment. Many of these achievements have been enabled, at least in part, by advances in ionizing radiation detectors. Radiology has been transformed by the implementation of multi-slice CT and digital x-ray imaging systems, with silver halide films now largely obsolete for many applications. Nuclear medicine has benefited from more sensitive, faster and higher-resolution detectors delivering ever-higher SPECT and PET image quality. PET/MR systems have been enabled by the development of gamma ray detectors that can operate in high magnetic fields. These huge advances in imaging have enabled equally impressive steps forward in radiotherapy delivery accuracy, with 4DCT, PET and MRI routinely used in treatment planning and online image guidance provided by cone-beam CT. The challenge of ensuring safe, accurate and precise delivery of highly complex radiation fields has also both driven and benefited from advances in radiation detectors. Detector systems have been developed for the measurement of electron, intensity-modulated and modulated arc x-ray, proton and ion beams, and around brachytherapy sources based on a very wide range of technologies. The types of measurement performed are equally wide, encompassing commissioning and quality assurance, reference dosimetry, in vivo dosimetry and personal and environmental monitoring. In this article, we briefly introduce the general physical characteristics and properties that are commonly used to describe the behaviour and performance of both discrete and imaging detectors. The physical principles of operation of calorimeters; ionization and charge detectors; semiconductor, luminescent, scintillating and chemical detectors; and radiochromic and radiographic films are then reviewed and their principle applications discussed. Finally, a general discussion of the application of detectors for x-ray nuclear medicine and ion beam imaging and dosimetry is presented. PMID:25229250

  16. Use of Sub-bandgap Illumination to Improve Radiation Detector Resolution of CdZnTe

    NASA Astrophysics Data System (ADS)

    Duff, Martine C.; Washington, Aaron L.; Teague, Lucile C.; Wright, Jonathan S.; Burger, Arnold; Groza, Michael; Buliga, Vladimir

    2015-09-01

    The performance of Cd1- x Zn x Te (CZT) materials for room-temperature gamma/x-ray radiation detection continues to improve in terms of material quality and detector design. In our prior publications, we investigated the use of multiple wavelengths of light (in the visible and infrared) to target charge carriers at various trap energies and physical positions throughout crystals. Light exposure significantly alters the charge mobility and improves carrier collection at the anode contact. This study presents an investigation of material performance as a radiation detector during such illumination. The decrease in charge trapping and increase in charge collection due to a higher probability of free electron release from traps contributed to an increase in the resolution-based performance of the detector through controlled illumination. We investigated the performance improvement of CZT crystals with previously known levels of intrinsic defects and secondary phases, at various voltages, light-emitting diode (LED) light wavelengths, and shaping times. Although our setup was clearly not optimized for radiation detector performance, it demonstrated substantial resolution improvements (based on full-width at half-maximum using 662-keV gamma rays from 137Cs upon illumination with 950-nm light) of 16% to 38% in comparison with unilluminated CZT under similar conditions. This manuscript includes discussion of the electrooptic behavior and its effect on performance. Additional testing and fabrication of a detector that incorporates such LED light optimization could lead to improved performance with existing detector-grade materials.

  17. The effects of 199 MeV proton radiation damage on CdZnTe photon detectors

    SciTech Connect

    Hull, E.L.; Pehl, R.H.; Varnell, L.S.

    1996-12-31

    Four CdZnTe detectors were irradiated with, 199 MeV protons to simulate the damaging radiation in space. The gamma-ray spectra of {sup 241}Am and {sup 57}Co as well as the detector leakage currents were monitored at room temperature to assess the effects of radiation damage. Surprisingly, after a fluence of a few x 10{sup 8} p/cm{sup 2}, gamma-ray peak shifts and resolution degradation became visible. After a fluence of 5 x 10{sup 9} p/cm{sup 2} the degradation was quite dramatic. An analysis of these effects clearly demonstrates that radiation damage causes electron trapping in CdZnTe detectors. No increase in leakage current or electronic noise was observed. Radiation damage effects in CdZnTe and germanium detectors are compared. CdZnTe detectors are {approximately}250 times more sensitive to radiation damage than germanium detectors per unit charge-drift distance.

  18. Investigation of GEM-Micromegas Detector on X-ray Beam of Synchrotron Radiation

    E-print Network

    YuLian Zhang; HuiRong Qi; BiTao Hu; ShengNan Fan; Bo Wang; Mei Liu; Jian Zhang; RongGuang Liu; GuangCai Chang; Peng Liu; Qun Ouyang; YuanBo Chen; FuTing Yi

    2013-07-01

    To solve the discharge of the standard Bulk Micromegas and GEM detector, the GEM-Micromegas detector was developed in Institute of High Energy Physics. Taking into account the advantages of the two detectors, one GEM foil was set as a preamplifier on the mesh of Micromegas in the structure and the GEM preamplification decreased the working voltage of Micromegas to reduce the effect of the discharge significantly. In the paper, the performance of detector in X-ray beam was studied at 1W2B laboratory of Beijing Synchrotron Radiation Facility. Finally, the result of the energy resolution under various X-ray energies was given in different working gases. It indicated that the GEM-Micromegas detector had the energy response capability in all the energy range and it could work better than the standard Bulk-Micromegas.

  19. Development of passive radiation detectors of improved sensitivity

    NASA Technical Reports Server (NTRS)

    Chakrabarty, M. R.

    1986-01-01

    The future development of a solid track high energy particle detector is discussed. The goal is to improve the sensitivity and lower the threshold of the detector. One most widely used material for such purpose is a plastic commercially known as CR-39. A scheme is presented which involves changing the formula of the monomer, diethylene glycol-bis-allyl carbonate. This is to be accomplished by substituting some heteroatoms for H and substituting sulfur atoms for oxygen in the ether linkages. Use of a new plasticizer to make the etched surface clearer than what has been accomplished as of today is suggested. Possible improvement in acquiring better tracks and increasing the ratio of V sub T/V sub B was planned. This is to be accomplished by changing the composition of the etchants, etching time, and etching temperature.

  20. Characterization of Silicon Photomultiplier Detectors using Cosmic Radiation

    NASA Astrophysics Data System (ADS)

    Zavala, Favian; Castro, Juan; Niduaza, Rexavalmar; Wedel, Zachary; Fan, Sewan; Ritt, Stefan; Fatuzzo, Laura

    2014-03-01

    The silicon photomultiplier light detector has gained a lot of attention lately in fields such as particle physics, astrophysics, and medical physics. Its popularity stems from its lower cost, compact size, insensitivity to magnetic fields, and its excellent ability to distinguish a quantized number of photons. They are normally operated at room temperature and biased above their breakdown voltages. As such, they may also exhibit properties that may hinder their optimal operation which include a thermally induced high dark count rate, after pulse effects, and cross talk from photons in nearby pixels. At this poster session, we describe our data analysis and our endeavor to characterize the multipixel photon counter (MPPC) detectors from Hamamatsu under different bias voltages and temperature conditions. Particularly, we describe our setup which uses cosmic rays to induce scintillation light delivered to the detector by wavelength shifting optical fibers and the use of a fast 1 GHz waveform sampler, the domino ring sampler (DRS4) digitizer board. Department of Education grant number P031S90007.

  1. Dosimetric characterization of a synthetic single crystal diamond detector in clinical radiation therapy small photon beams

    SciTech Connect

    Ciancaglioni, I.; Marinelli, Marco; Milani, E.; Prestopino, G.; Verona, C.; Verona-Rinati, G.; Consorti, R.; Petrucci, A.; De Notaristefani, F.

    2012-07-15

    Purpose: To determine the potentialities of synthetic single crystal diamond Schottky diodes for accurate dose measurements in radiation therapy small photon beams. Methods: The dosimetric properties of a diamond-based detector were assessed by comparison with a reference microionization chamber. The diamond device was operated at zero bias voltage under irradiation with high-energy radiotherapic photon beams. The stability of the detector response and its dose and dose rate dependence were measured. Different square field sizes ranging from 1 Multiplication-Sign 1 cm{sup 2} to 10 Multiplication-Sign 10 cm{sup 2} were used during comparative dose distribution measurements by means of percentage depth dose curves (PDDs), lateral beam profiles, and output factors. The angular and temperature dependence of the diamond detector response were also studied. Results: The detector response shows a deviation from linearity of less than {+-}0.5% in the 0.01-7 Gy range and dose rate dependence below {+-}0.5% in the 1-6 Gy/min range. PDDs and output factors are in good agreement with those measured by the reference ionization chamber within 1%. No angular dependence is observed by rotating the detector along its axis, while {approx}3.5% maximum difference is measured by varying the radiation incidence angle in the polar direction. The temperature dependence was investigated as well and a {+-}0.2% variation of the detector response is found in the 18-40 Degree-Sign C range. Conclusions: The obtained results indicate the investigated synthetic diamond-based detector as a candidate for small field clinical radiation dosimetry in advanced radiation therapy techniques.

  2. Physical design and Monte Carlo simulations of a space radiation detector onboard the SJ-10 satellite

    NASA Astrophysics Data System (ADS)

    Liu, Ya-Qing; Wang, Huan-Yu; Cui, Xing-Zhu; Peng, Wen-Xi; Fan, Rui-Rui; Liang, Xiao-Hua; Gao, Ming; Zhang, Yun-Long; Zhang, Cheng-Mo; Zhang, Jia-Yu; Yang, Jia-Wei; Wang, Jin-Zhou; Zhang, Fei; Dong, Yi-Fan; Guo, Dong-Ya; Zhou, Da-Wei

    2015-01-01

    A radiation gene box (RGB) onboard the SJ-10 satellite is a device carrying mice and drosophila cells to determine the biological effects of space radiation environment. The shielded fluxes of different radioactive sources were calculated and the linear energy transfers of ?-rays, electrons, protons and ?-particles in the tissue were acquired using A-150 tissue-equivalent plastic. Then, a conceptual model of a space radiation instrument employing three semiconductor sub-detectors for deriving the charged and uncharged radiation environment of the RGB was designed. The energy depositions in the three sub-detectors were classified into 15 channels (bins) in an algorithm derived from the Monte Carlo method. The physical feasibility of the conceptual instrument was also verified by Monte Carlo simulations.

  3. Exploring graphene field effect transistor devices to improve spectral resolution of semiconductor radiation detectors

    SciTech Connect

    Harrison, Richard Karl; Howell, Stephen Wayne; Martin, Jeffrey B.; Hamilton, Allister B.

    2013-12-01

    Graphene, a planar, atomically thin form of carbon, has unique electrical and material properties that could enable new high performance semiconductor devices. Graphene could be of specific interest in the development of room-temperature, high-resolution semiconductor radiation spectrometers. Incorporating graphene into a field-effect transistor architecture could provide an extremely high sensitivity readout mechanism for sensing charge carriers in a semiconductor detector, thus enabling the fabrication of a sensitive radiation sensor. In addition, the field effect transistor architecture allows us to sense only a single charge carrier type, such as electrons. This is an advantage for room-temperature semiconductor radiation detectors, which often suffer from significant hole trapping. Here we report on initial efforts towards device fabrication and proof-of-concept testing. This work investigates the use of graphene transferred onto silicon and silicon carbide, and the response of these fabricated graphene field effect transistor devices to stimuli such as light and alpha radiation.

  4. On the problem of the radiation hardness of SiC nuclear radiation detectors at high working temperatures

    SciTech Connect

    Ivanov, A. M. Sadokhin, A. V.; Strokan, N. B.; Lebedev, A. A.

    2011-10-15

    Owing to the radiation-induced pronounced conductivity compensation in silicon carbide, carrier localization (trapping) prevails over recombination in capture of nonequilibrium carriers. This makes it possible, by raising the temperature, to reduce the time of carrier retention by a trapping center to values shorter than the duration of signal shaping by electronic circuits. For structural defects created by 6.5-MeV protons, the temperature excluding degradation of the detector signal via carrier localization is estimated. The values of the appearing generation current the noise of which can restrict the operation of a detector in the spectrometric mode are determined.

  5. High-efficiency scintillation detector for combined of thermal and fast neutrons and gamma radiation

    DOEpatents

    Chiles, Marion M. (Knoxville, TN); Mihalczo, John T. (Oak Ridge, TN); Blakeman, Edward D. (Oak Ridge, TN)

    1989-01-01

    A scintillation based radiation detector for the combined detection of thermal neutrons, high-energy neutrons and gamma rays in a single detecting unit. The detector consists of a pair of scintillators sandwiched together and optically coupled to the light sensitive face of a photomultiplier tube. A light tight radiation pervious housing is disposed about the scintillators and a portion of the photomultiplier tube to hold the arrangement in assembly and provides a radiation window adjacent the outer scintillator through which the radiation to be detected enters the detector. The outer scintillator is formed of a material in which scintillations are produced by thermal-neutrons and the inner scintillator is formed of a material in which scintillations are produced by high-energy neutrons and gamma rays. The light pulses produced by events detected in both scintillators are coupled to the photomultiplier tube which produces a current pulse in response to each detected event. These current pulses may be processed in a conventional manner to produce a count rate output indicative of the total detected radiation even count rate. Pulse discrimination techniques may be used to distinguish the different radiations and their energy distribution.

  6. High-efficiency scintillation detector for combined detection of thermal and fast neutrons and gamma radiation

    DOEpatents

    Chiles, M.M.; Mihalczo, J.T.; Blakeman, E.D.

    1987-02-27

    A scintillation based radiation detector for the combined detection of thermal neutrons, high-energy neutrons and gamma rays in a single detecting unit. The detector consists of a pair of scintillators sandwiched together and optically coupled to the light sensitive face of a photomultiplier tube. A light tight radiation pervious housing is disposed about the scintillators and a portion of the photomultiplier tube to hold the arrangement in assembly and provides a radiation window adjacent the outer scintillator through which the radiation to be detected enters the detector. The outer scintillator is formed of a material in which scintillations are produced by thermal-neutrons and the inner scintillator is formed of a material in which scintillations are produced by high-energy neutrons and gamma rays. The light pulses produced by events detected in both scintillators are coupled to the photomultiplier tube which produces a current pulse in response to each detected event. These current pulses may be processed in a conventional manner to produce a count rate output indicative of the total detected radiation event count rate. Pulse discrimination techniques may be used to distinguish the different radiations and their energy distribution.

  7. Method and system for determining depth distribution of radiation-emitting material located in a source medium and radiation detector system for use therein

    DOEpatents

    Benke, Roland R. (Helotes, TX); Kearfott, Kimberlee J. (Ann Arbor, MI); McGregor, Douglas S. (Ann Arbor, MI)

    2003-03-04

    A method, system and a radiation detector system for use therein are provided for determining the depth distribution of radiation-emitting material distributed in a source medium, such as a contaminated field, without the need to take samples, such as extensive soil samples, to determine the depth distribution. The system includes a portable detector assembly with an x-ray or gamma-ray detector having a detector axis for detecting the emitted radiation. The radiation may be naturally-emitted by the material, such as gamma-ray-emitting radionuclides, or emitted when the material is struck by other radiation. The assembly also includes a hollow collimator in which the detector is positioned. The collimator causes the emitted radiation to bend toward the detector as rays parallel to the detector axis of the detector. The collimator may be a hollow cylinder positioned so that its central axis is perpendicular to the upper surface of the large area source when positioned thereon. The collimator allows the detector to angularly sample the emitted radiation over many ranges of polar angles. This is done by forming the collimator as a single adjustable collimator or a set of collimator pieces having various possible configurations when connected together. In any one configuration, the collimator allows the detector to detect only the radiation emitted from a selected range of polar angles measured from the detector axis. Adjustment of the collimator or the detector therein enables the detector to detect radiation emitted from a different range of polar angles. The system further includes a signal processor for processing the signals from the detector wherein signals obtained from different ranges of polar angles are processed together to obtain a reconstruction of the radiation-emitting material as a function of depth, assuming, but not limited to, a spatially-uniform depth distribution of the material within each layer. The detector system includes detectors having different properties (sensitivity, energy resolution) which are combined so that excellent spectral information may be obtained along with good determinations of the radiation field as a function of position.

  8. Development of radiation tolerant semiconductor detectors for the Super-LHC

    NASA Astrophysics Data System (ADS)

    Moll, M.; Adey, J.; Al-Ajili, A.; Alfieri, G.; Allport, P. P.; Artuso, M.; Assouak, S.; Avset, B. S.; Barabash, L.; Barcz, A.; Bates, R.; Biagi, S. F.; Bilei, G. M.; Bisello, D.; Blue, A.; Blumenau, A.; Boisvert, V.; Bolla, G.; Bondarenko, G.; Borchi, E.; Borrello, L.; Bortoletto, D.; Boscardin, M.; Bosisio, L.; Bowcock, T. J. V.; Brodbeck, T. J.; Broz, J.; Bruzzi, M.; Brzozowski, A.; Buda, M.; Buhmann, P.; Buttar, C.; Campabadal, F.; Campbell, D.; Candelori, A.; Casse, G.; Cavallini, A.; Charron, S.; Chilingarov, A.; Chren, D.; Cindro, V.; Collins, P.; Coluccia, R.; Contarato, D.; Coutinho, J.; Creanza, D.; Cunningham, W.; Dalla Betta, G.-F.; Dawson, I.; de Boer, W.; De Palma, M.; Demina, R.; Dervan, P.; Dittongo, S.; Dolezal, Z.; Dolgolenko, A.; Eberlein, T.; Eremin, V.; Fall, C.; Fasolo, F.; Fizzotti, F.; Fleta, C.; Focardi, E.; Forton, E.; Fretwurst, E.; Garcia, C.; Garcia-Navarro, J. E.; Gaubas, E.; Genest, M.-H.; Gill, K. A.; Giolo, K.; Glaser, M.; Goessling, C.; Golovine, V.; González Sevilla, S.; Gorelov, I.; Goss, J.; Gouldwell Bates, A.; Grégoire, G.; Gregori, P.; Grigoriev, E.; Grillo, A. A.; Groza, A.; Guskov, J.; Haddad, L.; Härkönen, J.; Hauler, F.; Hoeferkamp, M.; Hönniger, F.; Horazdovsky, T.; Horisberger, R.; Horn, M.; Houdayer, A.; Hourahine, B.; Hughes, G.; Ilyashenko, I.; Irmscher, K.; Ivanov, A.; Jarasiunas, K.; Johansen, K. M. H.; Jones, B. K.; Jones, R.; Joram, C.; Jungermann, L.; Kalinina, E.; Kaminski, P.; Karpenko, A.; Karpov, A.; Kazlauskiene, V.; Kazukauskas, V.; Khivrich, V.; Khomenkov, V.; Kierstead, J.; Klaiber-Lodewigs, J.; Klingenberg, R.; Kodys, P.; Kohout, Z.; Korjenevski, S.; Koski, M.; Kozlowski, R.; Kozodaev, M.; Kramberger, G.; Krasel, O.; Kuznetsov, A.; Kwan, S.; Lagomarsino, S.; Lassila-Perini, K.; Lastovetsky, V.; Latino, G.; Lazanu, S.; Lazanu, I.; Lebedev, A.; Lebel, C.; Leinonen, K.; Leroy, C.; Li, Z.; Lindström, G.; Linhart, V.; Litovchenko, A.; Litovchenko, P.; Lo Giudice, A.; Lozano, M.; Luczynski, Z.; Luukka, P.; Macchiolo, A.; Makarenko, L. F.; Mandi?, I.; Manfredotti, C.; Manna, N.; Marti i Garcia, S.; Marunko, S.; Mathieson, K.; Melone, J.; Menichelli, D.; Messineo, A.; Metcalfe, J.; Miglio, S.; Mikuž, M.; Miyamoto, J.; Monakhov, E.; Moscatelli, F.; Naoumov, D.; Nossarzewska-Orlowska, E.; Nysten, J.; Olivero, P.; OShea, V.; Palviainen, T.; Paolini, C.; Parkes, C.; Passeri, D.; Pein, U.; Pellegrini, G.; Perera, L.; Petasecca, M.; Piemonte, C.; Pignatel, G. U.; Pinho, N.; Pintilie, I.; Pintilie, L.; Polivtsev, L.; Polozov, P.; Popa, A.; Popule, J.; Pospisil, S.; Pozza, A.; Radicci, V.; Rafí, J. M.; Rando, R.; Roeder, R.; Rohe, T.; Ronchin, S.; Rott, C.; Roy, A.; Ruzin, A.; Sadrozinski, H. F. W.; Sakalauskas, S.; Scaringella, M.; Schiavulli, L.; Schnetzer, S.; Schumm, B.; Sciortino, S.; Scorzoni, A.; Segneri, G.; Seidel, S.; Seiden, A.; Sellberg, G.; Sellin, P.; Sentenac, D.; Shipsey, I.; Sicho, P.; Sloan, T.; Solar, M.; Son, S.; Sopko, B.; Sopko, V.; Spencer, N.; Stahl, J.; Stolze, D.; Stone, R.; Storasta, J.; Strokan, N.; Sudzius, M.; Surma, B.; Suvorov, A.; Svensson, B. G.; Tipton, P.; Tomasek, M.; Tsvetkov, A.; Tuominen, E.; Tuovinen, E.; Tuuva, T.; Tylchin, M.; Uebersee, H.; Uher, J.; Ullán, M.; Vaitkus, J. V.; Velthuis, J.; Verbitskaya, E.; Vrba, V.; Wagner, G.; Wilhelm, I.; Worm, S.; Wright, V.; Wunstorf, R.; Yiuri, Y.; Zabierowski, P.; Zaluzhny, A.; Zavrtanik, M.; Zen, M.; Zhukov, V.; Zorzi, N.

    2005-07-01

    The envisaged upgrade of the Large Hadron Collider (LHC) at CERN towards the Super-LHC (SLHC) with a 10 times increased luminosity of 10 35 cm -2 s -1 will present severe challenges for the tracking detectors of the SLHC experiments. Unprecedented high radiation levels and track densities and a reduced bunch crossing time in the order of 10 ns as well as the need for cost effective detectors have called for an intensive R&D program. The CERN RD50 collaboration "Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders" is working on the development of semiconductor sensors matching the requirements of the SLHC. Sensors based on defect engineered silicon like Czochralski, epitaxial and oxygen enriched silicon have been developed. With 3D, Semi-3D and thin detectors new detector concepts have been evaluated and a study on the use of standard and oxygen enriched p-type silicon detectors revealed a promising approach for radiation tolerant cost effective devices. These and other most recent advancements of the RD50 collaboration are presented.

  9. Preliminary Results from an Investigation into Nanostructured Nuclear Radiation Detectors for Non-Proliferation Applications

    SciTech Connect

    ,

    2012-10-01

    In recent years, the concept of embedding composite scintillators consisting of nanosized inorganic crystals in an organic matrix has been actively pursued. Nanocomposite detectors have the potential to meet many of the homeland security, non-proliferation, and border and cargo-screening needs of the nation and, by virtue of their superior nuclear identification capability over plastic, at roughly the same cost as plastic, have the potential to replace all plastic detectors. Nanocomposites clearly have the potential of being a gamma ray detection material that would be sensitive yet less expensive and easier to produce on a large scale than growing large, whole crystals of similar sensitivity. These detectors would have a broad energy range and a sufficient energy resolution to perform isotopic identification. The material can also be fabricated on an industrial scale, further reducing cost. This investigation focused on designing and fabricating prototype core/shell and quantum dot (QD) detectors. Fourteen core/shell and four QD detectors, all with the basic consistency of a mixture of nanoparticles in a polymer matrix with different densities of nanoparticles, were prepared. Nanoparticles with sizes <10 nm were fabricated, embedded in a polystyrene matrix, and the resultant scintillators’ radiation detector properties were characterized. This work also attempted to extend the gamma energy response on both low- and high-energy regimes by demonstrating the ability to detect low-energy and high-energy gamma rays. Preliminary results of this investigation are consistent with a significant response of these materials to nuclear radiation.

  10. Mixed ionic-electronic conductor-based radiation detectors and methods of fabrication

    DOEpatents

    Conway, Adam; Beck, Patrick R; Graff, Robert T; Nelson, Art; Nikolic, Rebecca J; Payne, Stephen A; Voss, Lars; Kim, Hadong

    2015-04-07

    A method of fabricating a mixed ionic-electronic conductor (e.g. TlBr)-based radiation detector having halide-treated surfaces and associated methods of fabrication, which controls polarization of the mixed ionic-electronic MIEC material to improve stability and operational lifetime.

  11. Using Ionizing Radiation Detectors. Module 11. Vocational Education Training in Environmental Health Sciences.

    ERIC Educational Resources Information Center

    Consumer Dynamics Inc., Rockville, MD.

    This module, one of 25 on vocational education training for careers in environmental health occupations, contains self-instructional materials on using ionizing radiation detectors. Following guidelines for students and instructors and an introduction that explains what the student will learn are three lessons: (1) naming and telling the function…

  12. Low-cost cadmium zinc telluride radiation detectors based on electron-transport-only designs

    SciTech Connect

    B. A. Brunett; J. C. Lund; J. M. Van Scyoc; N. R. Hilton; E. Y. Lee; R. B. James

    1999-01-01

    The goal of this project was to utilize a novel device design to build a compact, high resolution, room temperature operated semiconductor gamma ray sensor. This sensor was constructed from a cadmium zinc telluride (CZT) crystal. It was able to both detect total radiation intensity and perform spectroscopy on the detected radiation. CZT detectors produced today have excellent electron charge carrier collection, but suffer from poor hole collection. For conventional gamma-ray spectrometers, both the electrons and holes must be collected with high efficiency to preserve energy resolution. The requirement to collect the hole carriers, which have relatively low lifetimes, limits the efficiency and performance of existing experimental devices. By implementing novel device designs such that the devices rely only on the electron signal for energy information, the sensitivity of the sensors for detecting radiation can be increased substantially. In this report the authors describe a project to develop a new type of electron-only CZT detector. They report on their successful efforts to design, implement and test these new radiation detectors. In addition to the design and construction of the sensors the authors also report, in considerable detail, on the electrical characteristics of the CZT crystals used to make their detectors.

  13. Spacecraft to Spacecraft Coherent Laser Tracking as a Xylophone Interferometer Detector of Gravitational Radiation

    NASA Technical Reports Server (NTRS)

    Tinto, M.

    1998-01-01

    Searches for gravitational radiation can be performed in space with two spacecraft tracking each other with coherent laser light. This experimental technique could be implemented with two spacecraft carrying an appropriate optical payload, or with the proposed broad-band, space-based laser interferometer detectors of gravitational waves operated in this non-interferometric mode.

  14. THE AMS-02 TRANSITION RADIATION DETECTOR FOR THE INTERNATIONAL SPACE STATION

    E-print Network

    Roma "La Sapienza", Università di

    1 THE AMS-02 TRANSITION RADIATION DETECTOR FOR THE INTERNATIONAL SPACE STATION A. BARTOLONI I The Alpha Magnetic Spectrometer (AMS-02) is a large experiment in the International Space Station (ISS on the International Space Station (ISS) to measure primary cosmic ray spectra in space [1]. A key element for dark

  15. Gas-Monitor Detector for Intense and Pulsed VUV/EUV Free-Electron Laser Radiation

    SciTech Connect

    Sorokin, A.A.; Bobashev, S.V.; Shmaenok, L.A.; Feldhaus, J.; Gerth, Ch.; Hahn, U.; Steeg, B.; Tiedtke, K.; Treusch, R.; Gottwald, A.; Kroth, U.; Richter, M.

    2004-05-12

    In the framework of current developments of new powerful VUV and EUV radiation sources, like VUV free-electron-lasers or EUV plasma sources for 13-nm lithography, we developed a gas-monitor detector in order to measure the photon flux of highly intense and extremely pulsed VUV and EUV radiation in absolute terms. The device is based on atomic photoionization of a rare gas at low particle density. Therefore, it is free of degradation and almost transparent, which allows the detector to be used as a continuously working beam-intensity monitor. The extended dynamic range of the detector allowed its calibration with relative standard uncertainties of 4% in the Radiometry Laboratory of the Physikalisch-Technische Bundesanstalt at the electron-storage ring BESSY II in Berlin using spectrally dispersed synchrotron radiation at low photon intensities and its utilization for absolute photon flux measurements of high power sources. In the present contribution, we describe the design of the detector and its application for the characterization of VUV free-electron-laser radiation at the TESLA test facility in Hamburg. By first pulse resolved measurements, a peak power of more than 100 MW at a wavelength of 87 nm was detected.

  16. Principal Component Analysis for pulse-shape discrimination of scintillation radiation detectors

    NASA Astrophysics Data System (ADS)

    Alharbi, T.

    2016-01-01

    In this paper, we report on the application of Principal Component analysis (PCA) for pulse-shape discrimination (PSD) of scintillation radiation detectors. The details of the method are described and the performance of the method is experimentally examined by discriminating between neutrons and gamma-rays with a liquid scintillation detector in a mixed radiation field. The performance of the method is also compared against that of the conventional charge-comparison method, demonstrating the superior performance of the method particularly at low light output range. PCA analysis has the important advantage of automatic extraction of the pulse-shape characteristics which makes the PSD method directly applicable to various scintillation detectors without the need for the adjustment of a PSD parameter.

  17. Comparison of cosmic rays radiation detectors on-board commercial jet aircraft.

    PubMed

    Kuban?ák, Ján; Ambrožová, Iva; Brabcová, Kate?ina Pachnerová; Jak?bek, Jan; Kyselová, Dagmar; Ploc, Ond?ej; Bemš, Július; Št?pán, Václav; Uchihori, Yukio

    2015-06-01

    Aircrew members and passengers are exposed to increased rates of cosmic radiation on-board commercial jet aircraft. The annual effective doses of crew members often exceed limits for public, thus it is recommended to monitor them. In general, the doses are estimated via various computer codes and in some countries also verified by measurements. This paper describes a comparison of three cosmic rays detectors, namely of the (a) HAWK Tissue Equivalent Proportional Counter; (b) Liulin semiconductor energy deposit spectrometer and (c) TIMEPIX silicon semiconductor pixel detector, exposed to radiation fields on-board commercial Czech Airlines company jet aircraft. Measurements were performed during passenger flights from Prague to Madrid, Oslo, Tbilisi, Yekaterinburg and Almaty, and back in July and August 2011. For all flights, energy deposit spectra and absorbed doses are presented. Measured absorbed dose and dose equivalent are compared with the EPCARD code calculations. Finally, the advantages and disadvantages of all detectors are discussed. PMID:25979739

  18. Dichroic filters to protect milliwatt far-infrared detectors from megawatt ECRH radiation

    SciTech Connect

    Bertschinger, G.; Oosterbeek, J. W.; Endres, C. P.; Lewen, F.

    2008-10-15

    Dichroic filters have been used to shield effectively the far infrared (FIR) detectors at the interferometer/polarimeter on TEXTOR. The filters consist of metal foils with regular holes, the hole diameter, the mutual spacing and the thickness of the foils are chosen to transmit radiation at the design frequency with transmission >90%. The attenuation at the low frequency end of the bandpass filter is about 30 dB per octave, the high frequency transmission is between 20% and 40%. The filters have been used to block the stray radiation from the megawatt microwave heating beam to the detectors of the FIR interferometer, operating with power on the detector in the milliwatt range. If required, the low frequency attenuation can be still enhanced, without compromising the transmission in the passband. The FIR interferometer used for plasma density and position control is no longer disturbed by electromagnetic waves used for plasma heating.

  19. Detectors

    DOEpatents

    Orr, Christopher Henry (Calderbridge, GB); Luff, Craig Janson (Calderbridge, GB); Dockray, Thomas (Calderbridge, GB); Macarthur, Duncan Whittemore (Los Alamos, NM); Bounds, John Alan (Los Alamos, NM); Allander, Krag (Los Alamos, NM)

    2002-01-01

    The apparatus and method provide techniques through which both alpha and beta emission determinations can be made simultaneously using a simple detector structure. The technique uses a beta detector covered in an electrically conducting material, the electrically conducting material discharging ions generated by alpha emissions, and as a consequence providing a measure of those alpha emissions. The technique also offers improved mountings for alpha detectors and other forms of detectors against vibration and the consequential effects vibration has on measurement accuracy.

  20. EFFECT OF SURFACE PREPARATION TECHNIQUE ON THE RADIATION DETECTOR PERFORMANCEOF CDZNTE

    SciTech Connect

    Duff, M

    2007-05-23

    Synthetic CdZnTe (CZT) semiconducting crystals are highly suitable for the room temperature-based detection of gamma radiation. The surface preparation of Au contacts on surfaces of CZT detectors is typically conducted after (1) polishing to remove artifacts from crystal sectioning and (2) chemical etching, which removes residual mechanical surface damage however etching results in a Te rich surface layer that is prone to oxidize. Our studies show that CZT surfaces that are only polished (as opposed to polished and etched) can be contacted with Au and will yield lower surface currents. Due to their decreased dark currents, these as-polished surfaces can be used in the fabrication of gamma detectors exhibiting a higher performance than polished and etched surfaces with relatively less peak tailing and greater energy resolution. CdZnTe or ''CZT'' crystals are attractive to use in homeland security applications because they detect radiation at room temperature and do not require low temperature cooling as with silicon- and germanium-based detectors. Relative to germanium and silicon detectors, CZT is composed of higher Z elements and has a higher density, which gives it greater ''stopping power'' for gamma rays making a more efficient detector. Single crystal CZT materials with high bulk resistivity ({rho}>10{sup 10} {Omega} x cm) and good mobility-lifetime products are also required for gamma-ray spectrometric applications. However, several factors affect the detector performance of CZT are inherent to the as grown crystal material such as the presence of secondary phases, point defects and the presence of impurities (as described in a literature review by R. James and researchers). These and other factors can limit radiation detector performance such as low resistivity, which causes a large electronic noise and the presence of traps and other heterogeneities, which result in peak tailing and poor energy resolution.

  1. Calibration of modified Liulin detector for cosmic radiation measurements on-board aircraft.

    PubMed

    Kyselová, D; Ambrožová, I; Krist, P; Kuban?ák, J; Uchihori, Y; Kitamura, H; Ploc, O

    2015-06-01

    The annual effective doses of aircrew members often exceed the limit of 1 mSv for the public due to the increased level of cosmic radiation at the flight altitudes, and thus, it is recommended to monitor them. Aircrew dosimetry is usually performed using special computer programs mostly based on results of Monte Carlo simulations. Contemporary, detectors are used mostly for validation of these computer codes, verification of effective dose calculations and for research purposes. One of such detectors is active silicon semiconductor deposited energy spectrometer Liulin. Output quantities of measurement with the Liulin detector are the absorbed dose in silicon D and the ambient dose equivalent H*(10); to determine it, two calibrations are necessary. The purpose of this work was to develop a calibration methodology that can be used to convert signal from the detector to D independently on calibration performed at Heavy Ion Medical Accelerator facility in Chiba, Japan. PMID:25979744

  2. Digital configurable instrument for emulation of signals from radiation detectors

    SciTech Connect

    Abba, A.; Caponio, F.; Geraci, A.

    2014-01-15

    The paper presents a digital instrument characterized by a specially designed architecture that is able to emulate in real time signals from a generic radiation detection system. The instrument is not a pulse generator of recorded shapes but a synthesizer of random pulses compliant to programmable statistics for height and starting time of events. Completely programmable procedures for emulation of noise, disturbances, and reference level variation are implemented.

  3. Development of a plasma panel radiation detector: recent progress and key issues

    E-print Network

    Silver, Yiftah; Beene, James R; Benhammou, Yan; Ben-Moshe, Meny; Chapman, J W; Dai, Tiesheng; Etzion, Erez; Ferretti, Claudio; Guttman, Nir; Friedman, Peter S; Levin, Daniel S; Ritt, S; Varner, Robert L; Weaverdyck, Curtis; Zhou, Bing

    2012-01-01

    A radiation detector based on plasma display panel technology, which is the principal component of plasma television displays is presented. Plasma Panel Sensor (PPS) technology is a variant of micropattern gas radiation detectors. The PPS is conceived as an array of sealed plasma discharge gas cells which can be used for fast response (O(5ns) per pixel), high spatial resolution detection (pixel pitch can be less than 100 micrometer) of ionizing and minimum ionizing particles. The PPS is assembled from non-reactive, intrinsically radiation-hard materials: glass substrates, metal electrodes and inert gas mixtures. We report on the PPS development program, including simulations and design and the first laboratory studies which demonstrate the usage of plasma display panels in measurements of cosmic ray muons, as well as the expansion of experimental results on the detection of betas from radioactive sources.

  4. Radiation Measurements Performed with Active Detectors Relevant for Human Space Exploration.

    PubMed

    Narici, Livio; Berger, Thomas; Matthiä, Daniel; Reitz, Günther

    2015-01-01

    A reliable radiation risk assessment in space is a mandatory step for the development of countermeasures and long-duration mission planning in human spaceflight. Research in radiobiology provides information about possible risks linked to radiation. In addition, for a meaningful risk evaluation, the radiation exposure has to be assessed to a sufficient level of accuracy. Consequently, both the radiation models predicting the risks and the measurements used to validate such models must have an equivalent precision. Corresponding measurements can be performed both with passive and active devices. The former is easier to handle, cheaper, lighter, and smaller but they measure neither the time dependence of the radiation environment nor some of the details useful for a comprehensive radiation risk assessment. Active detectors provide most of these details and have been extensively used in the International Space Station. To easily access such an amount of data, a single point access is becoming essential. This review presents an ongoing work on the development of a tool that allows obtaining information about all relevant measurements performed with active detectors providing reliable inputs for radiation model validation. PMID:26697408

  5. Radiation Measurements Performed with Active Detectors Relevant for Human Space Exploration

    PubMed Central

    Narici, Livio; Berger, Thomas; Matthiä, Daniel; Reitz, Günther

    2015-01-01

    A reliable radiation risk assessment in space is a mandatory step for the development of countermeasures and long-duration mission planning in human spaceflight. Research in radiobiology provides information about possible risks linked to radiation. In addition, for a meaningful risk evaluation, the radiation exposure has to be assessed to a sufficient level of accuracy. Consequently, both the radiation models predicting the risks and the measurements used to validate such models must have an equivalent precision. Corresponding measurements can be performed both with passive and active devices. The former is easier to handle, cheaper, lighter, and smaller but they measure neither the time dependence of the radiation environment nor some of the details useful for a comprehensive radiation risk assessment. Active detectors provide most of these details and have been extensively used in the International Space Station. To easily access such an amount of data, a single point access is becoming essential. This review presents an ongoing work on the development of a tool that allows obtaining information about all relevant measurements performed with active detectors providing reliable inputs for radiation model validation. PMID:26697408

  6. Advanced radiation detector development: Advanced semiconductor detector development: Development of a room-temperature, gamma ray detector using gallium arsenide to develop an electrode detector. Annual progress report, September 30, 1994--September 29, 1995

    SciTech Connect

    Knoll, G.F.

    1995-11-01

    The advanced detector development project at the University of Michigan has completed the first full year of its current funding. The general goals are the development of radiation detectors and spectrometers that are capable of portable room temperature operation. Over the past 12 months, the authors have worked primarily in the development of semiconductor spectrometers with ``single carrier`` response that offer the promise of room temperature operation and good energy resolution in gamma ray spectroscopy. They have also begun a small scale effort at investigating the properties of a small non-spectroscopic detector system with directional characteristics that will allow identification of the approximate direction in which gamma rays are incident. These activities have made use of the extensive clean room facilities at the University of Michigan for semiconductor device fabrication, and also the radiation measurement capabilities provided in the laboratory in the Phoenix Building on the North Campus.

  7. Effects of Te inclusions on the performance of CdZnTe radiation detectors

    SciTech Connect

    Bolotnikov,A.E.; Abdul-Jabber, N. M.; Babalola, O. S.; Camarda, G. S.; Cui, Y.; Hossain, A. M.; Jackson, E. M.; Jackson, H. C.; James, J. A.; Kohman, K. T.; Luryi, A. L.; James, R. B.

    2008-10-19

    Te inclusions existing at high concentrations in CdZnTe (CZT) material can degrade the performance of CZT detectors. These microscopic defects trap the free electrons generated by incident radiation, so entailing significant fluctuations in the total collected charge and thereby strongly affecting the energy resolution of thick (long-drift) detectors. Such effects were demonstrated in thin planar detectors, and, in many cases, they proved to be the dominant cause of the low performance of thick detectors, wherein the fluctuations in the charge losses accumulate along the charge's drift path. We continued studying this effect using different tools and techniques. We employed a dedicated beamline recently established at BNL's National Synchrotron Light Source for characterizing semiconductor radiation detectors, along with an IR transmission microscope system, the combination of which allowed us to correlate the concentration of defects with the devices performances. We present here our new results from testing over 50 CZT samples grown by different techniques. Our goals are to establish tolerable limits on the size and concentrations of these detrimental Te inclusions in CZT material, and to provide feedback to crystal growers to reduce their numbers in the material.

  8. Radiation Effects of n-type, Low Resistivity, Spiral Silicon Drift Detector Hybrid Systems

    SciTech Connect

    Chen W.; De Geronimo G.; Carini, G.A.; Gaskin, J.A.; Keister, J.W.; Li, S.; Li, Z.; Ramsey, B.D.; Siddons, D.P.; Smith, G.C.; Verbitskaya, E.

    2011-11-15

    We have developed a new thin-window, n-type, low-resistivity, spiral silicon drift detector (SDD) array - to be used as an extraterrestrial X-ray spectrometer (in varying environments) for NASA. To achieve low-energy response, a thin SDD entrance window was produced using a previously developed method. These thin-window devices were also produced on lower resistivity, thinner, n-type, silicon material, effectively ensuring their radiation hardness in anticipation of operation in potentially harsh radiation environments (such as found around the Jupiter system). Using the Indiana University Cyclotron Facility beam line RERS1, we irradiated a set of suitable diodes up to 5 Mrad and the latest iteration of our ASICs up to 12 Mrad. Then we irradiated two hybrid detectors consisting of newly, such-produced in-house (BNL) SDD chips bonded with ASICs with doses of 0.25 Mrad and 1 Mrad. Also we irradiated another hybrid detector consisting of previously produced (by KETEK) on n-type, high-resistivity SDD chip bonded with BNL's ASICs with a dose of 1 Mrad. The measurement results of radiated diodes (up to 5 Mrad), ASICs (up to 12 Mrad) and hybrid detectors (up to 1 Mrad) are presented here.

  9. Recent advancements in the development of radiation hard semiconductor detectors for S-LHC

    NASA Astrophysics Data System (ADS)

    Fretwurst, E.; Adey, J.; Al-Ajili, A.; Alfieri, G.; Allport, P. P.; Artuso, M.; Assouak, S.; Avset, B. S.; Barabash, L.; Barcz, A.; Bates, R.; Biagi, S. F.; Bilei, G. M.; Bisello, D.; Blue, A.; Blumenau, A.; Boisvert, V.; Bolla, G.; Bondarenko, G.; Borchi, E.; Borrello, L.; Bortoletto, D.; Boscardin, M.; Bosisio, L.; Bowcock, T. J. V.; Brodbeck, T. J.; Broz, J.; Bruzzi, M.; Brzozowski, A.; Buda, M.; Buhmann, P.; Buttar, C.; Campabadal, F.; Campbell, D.; Candelori, A.; Casse, G.; Cavallini, A.; Charron, S.; Chilingarov, A.; Chren, D.; Cindro, V.; Collins, P.; Coluccia, R.; Contarato, D.; Coutinho, J.; Creanza, D.; Cunningham, L.; Dalla Betta, G.-F.; Dawson, I.; de Boer, W.; De Palma, M.; Demina, R.; Dervan, P.; Dittongo, S.; Dolezal, Z.; Dolgolenko, A.; Eberlein, T.; Eremin, V.; Fall, C.; Fasolo, F.; Ferbel, T.; Fizzotti, F.; Fleta, C.; Focardi, E.; Forton, E.; Garcia, C.; Garcia-Navarro, J. E.; Gaubas, E.; Genest, M.-H.; Gill, K. A.; Giolo, K.; Glaser, M.; Goessling, C.; Golovine, V.; González Sevilla, S.; Gorelov, I.; Goss, J.; Gouldwell Bates, A.; Grégoire, G.; Gregori, P.; Grigoriev, E.; Grillo, A. A.; Groza, A.; Guskov, J.; Haddad, L.; Härkönen, J.; Hauler, F.; Hoeferkamp, M.; Hönniger, F.; Horazdovsky, T.; Horisberger, R.; Horn, M.; Houdayer, A.; Hourahine, B.; Hughes, G.; Ilyashenko, I.; Irmscher, K.; Ivanov, A.; Jarasiunas, K.; Johansen, K. M. H.; Jones, B. K.; Jones, R.; Joram, C.; Jungermann, L.; Kalinina, E.; Kaminski, P.; Karpenko, A.; Karpov, A.; Kazlauskiene, V.; Kazukauskas, V.; Khivrich, V.; Khomenkov, V.; Kierstead, J.; Klaiber-Lodewigs, J.; Klingenberg, R.; Kodys, P.; Kohout, Z.; Korjenevski, S.; Koski, M.; Kozlowski, R.; Kozodaev, M.; Kramberger, G.; Krasel, O.; Kuznetsov, A.; Kwan, S.; Lagomarsino, S.; Lassila-Perini, K.; Lastovetsky, V.; Latino, G.; Lazanu, I.; Lazanu, S.; Lebedev, A.; Lebel, C.; Leinonen, K.; Leroy, C.; Li, Z.; Lindström, G.; Linhart, V.; Litovchenko, P.; Litovchenko, A.; Lo Giudice, A.; Lozano, M.; Luczynski, Z.; Luukka, P.; Macchiolo, A.; Makarenko, L. F.; Mandi?, I.; Manfredotti, C.; Manna, N.; Marti i Garcia, S.; Marunko, S.; Mathieson, K.; Melone, J.; Menichelli, D.; Messineo, A.; Metcalfe, J.; Miglio, S.; Mikuž, M.; Miyamoto, J.; Moll, M.; Monakhov, E.; Moscatelli, F.; Naoumov, D.; Nossarzewska-Orlowska, E.; Nysten, J.; Olivero, P.; Oshea, V.; Palviainen, T.; Paolini, C.; Parkes, C.; Passeri, D.; Pein, U.; Pellegrini, G.; Perera, L.; Petasecca, M.; Piemonte, C.; Pignatel, G. U.; Pinho, N.; Pintilie, I.; Pintilie, L.; Polivtsev, L.; Polozov, P.; Popa, A.; Popule, J.; Pospisil, S.; Pozza, A.; Radicci, V.; Rafí, J. M.; Rando, R.; Roeder, R.; Rohe, T.; Ronchin, S.; Rott, C.; Roy, A.; Ruzin, A.; Sadrozinski, H. F. W.; Sakalauskas, S.; Scaringella, M.; Schiavulli, L.; Schnetzer, S.; Schumm, B.; Sciortino, S.; Scorzoni, A.; Segneri, G.; Seidel, S.; Seiden, A.; Sellberg, G.; Sellin, P.; Sentenac, D.; Shipsey, I.; Sicho, P.; Sloan, T.; Solar, M.; Son, S.; Sopko, B.; Sopko, V.; Spencer, N.; Stahl, J.; Stolze, D.; Stone, R.; Storasta, J.; Strokan, N.; Sudzius, M.; Surma, B.; Suvorov, A.; Svensson, B. G.; Tipton, P.; Tomasek, M.; Tsvetkov, A.; Tuominen, E.; Tuovinen, E.; Tuuva, T.; Tylchin, M.; Uebersee, H.; Uher, J.; Ullán, M.; Vaitkus, J. V.; Velthuis, J.; Verbitskaya, E.; Vrba, V.; Wagner, G.; Wilhelm, I.; Worm, S.; Wright, V.; Wunstorf, R.; Yiuri, Y.; Zabierowski, P.; Zaluzhny, A.; Zavrtanik, M.; Zen, M.; Zhukov, V.; Zorzi, N.

    2005-10-01

    The proposed luminosity upgrade of the Large Hadron Collider (S-LHC) at CERN will demand the innermost layers of the vertex detectors to sustain fluences of about 10 16 hadrons/cm 2. Due to the high multiplicity of tracks, the required spatial resolution and the extremely harsh radiation field new detector concepts and semiconductor materials have to be explored for a possible solution of this challenge. The CERN RD50 collaboration "Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders" has started in 2002 an R&D program for the development of detector technologies that will fulfill the requirements of the S-LHC. Different strategies are followed by RD50 to improve the radiation tolerance. These include the development of defect engineered silicon like Czochralski, epitaxial and oxygen-enriched silicon and of other semiconductor materials like SiC and GaN as well as extensive studies of the microscopic defects responsible for the degradation of irradiated sensors. Further, with 3D, Semi-3D and thin devices new detector concepts have been evaluated. These and other recent advancements of the RD50 collaboration are presented and discussed.

  10. Prototype Radiation Detector Positioning System For The Automated Nondestructive Assay Of Uf6 Cylinders

    SciTech Connect

    Hatchell, Brian K.; Valdez, Patrick LJ; Orton, Christopher R.; Mace, Emily K.

    2011-08-07

    International Atomic Energy Agency (IAEA) inspectors currently perform periodic inspections at uranium enrichment plants to verify UF6 cylinder enrichment declarations. Measurements are typically performed with handheld high-resolution sensors on a sampling of cylinders taken to be representative of the facility’s entire cylinder inventory. These measurements are time-consuming, expensive, and assay only a small fraction of the total cylinder volume. An automated nondestructive assay system capable of providing enrichment measurements over the full volume of the cylinder could improve upon current verification practices in terms of efficiency and assay accuracy. This paper describes an approach denoted the Integrated Cylinder Verification Station (ICVS) that supports 100% cylinder verification, provides volume-averaged cylinder enrichment assay, and reduces inspector manpower needs. To allow field measurements to be collected to validate data collection algorithms, a prototype radiation detector positioning system was constructed. The system was designed to accurately position an array of radiation detectors along the length of a cylinder to measure UF6 enrichment. A number of alternative radiation shields for the detectors were included with the system. A collimated gamma-ray spectrometer module that allows translation of the detectors in the surrounding shielding to adjust the field of view, and a collimating plug in the end to further reduce the low-energy field of view, were also developed. Proof-of-principle measurements of neutron and high-energy gamma-ray signatures, using moderated neutron detectors and large-volume spectrometers in a fixed-geometry, portal-like configuration, supported an early assessment of the viability of the concept. The system has been used successfully on two testing campaigns at an AREVA fuel fabrication plant to scan over 30 product cylinders. This paper will describe the overall design of the detector positioning system and provide an overview of the Integrated Cylinder Verification Station (ICVS) approach.

  11. The simulation of the LANFOS-H food radiation contamination detector using Geant4 package

    NASA Astrophysics Data System (ADS)

    Piotrowski, Lech Wiktor; Casolino, Marco; Ebisuzaki, Toshikazu; Higashide, Kazuhiro

    2015-02-01

    Recent incident in the Fukushima power plant caused a growing concern about the radiation contamination and resulted in lowering the Japanese limits for the permitted amount of 137Cs in food to 100 Bq/kg. To increase safety and ease the concern we are developing LANFOS (Large Food Non-destructive Area Sampler)-a compact, easy to use detector for assessment of radiation in food. Described in this paper LANFOS-H has a 4 ? coverage to assess the amount of 137Cs present, separating it from the possible 40K food contamination. Therefore, food samples do not have to be pre-processed prior to a test and can be consumed after measurements. It is designed for use by non-professionals in homes and small institutions such as schools, showing safety of the samples, but can be also utilized by specialists providing radiation spectrum. Proper assessment of radiation in food in the apparatus requires estimation of the ? conversion factor of the detectors-how many ? photons will produce a signal. In this paper we show results of the Monte Carlo estimation of this factor for various approximated shapes of fish, vegetables and amounts of rice, performed with Geant4 package. We find that the conversion factor combined from all the detectors is similar for all food types and is around 37%, varying maximally by 5% with sample length, much less than for individual detectors. The different inclinations and positions of samples in the detector introduce uncertainty of 1.4%. This small uncertainty validates the concept of a 4 ? non-destructive apparatus.

  12. The iQID Camera An Ionizing-Radiation Quantum Imaging Detector

    SciTech Connect

    Miller, Brian W.; Gregory, Stephanie J.; Fuller, Erin S.; Barrett, Harrison H.; Barber, Bradford H.; Furenlid, Lars R.

    2014-06-11

    Abstract We have developed and tested a novel, ionizing-radiation Quantum Imaging Detector (iQID). This scintillation-based detector was originally developed as a high-resolution gamma-ray imager, called BazookaSPECT, for use in single-photon emission computed tomography (SPECT). Recently, we have investigated the detectors response and imaging potential with other forms of ionizing radiation including alpha, neutron, beta, and fission fragment particles. The detector’s response to a broad range of ionizing radiation has prompted its new title. The principle operation of the iQID camera involves coupling a scintillator to an image intensifier. The scintillation light generated particle interactions is optically amplified by the intensifier and then re-imaged onto a CCD/CMOS camera sensor. The intensifier provides sufficient optical gain that practically any CCD/CMOS camera can be used to image ionizing radiation. Individual particles are identified and their spatial position (to sub-pixel accuracy) and energy are estimated on an event-by-event basis in real time using image analysis algorithms on high-performance graphics processing hardware. Distinguishing features of the iQID camera include portability, large active areas, high sensitivity, and high spatial resolution (tens of microns). Although modest, iQID has energy resolution that is sufficient to discrimate between particles. Additionally, spatial features of individual events can be used for particle discrimination. An important iQID imaging application that has recently been developed is single-particle, real-time digital autoradiography. We present the latest results and discuss potential applications.

  13. Initial Field Measurements with the Multisensor Airborne Radiation Survey (MARS) High Purity Germanium (HPGe) Detector Array

    SciTech Connect

    Fast, James E.; Bonebrake, Christopher A.; Dorow, Kevin E.; Glasgow, Brian D.; Jensen, Jeffrey L.; Morris, Scott J.; Orrell, John L.; Pitts, W. Karl; Rohrer, John S.; Todd, Lindsay C.

    2010-06-29

    Abstract: The Multi-sensor Airborne Radiation Survey (MARS) project has developed a new single cryostat detector array design for high purity germanium (HPGe) gamma ray spectrometers that achieves the high detection efficiency required for stand-off detection and actionable characterization of radiological threats. This approach is necessary since a high efficiency HPGe detector can only be built as an array due to limitations in growing large germanium crystals. The system is ruggedized and shock mounted for use in a variety of field applications. This paper reports on results from initial field measurements conducted in a truck and on two different boats.

  14. Earth radiation budget measurement from a spinning satellite: Conceptual design of detectors

    NASA Technical Reports Server (NTRS)

    Sromovsky, L. A.; Revercomb, H. E.; Suomi, V. E.

    1975-01-01

    The conceptual design, sensor characteristics, sensor performance and accuracy, and spacecraft and orbital requirements for a spinning wide-field-of-view earth energy budget detector were investigated. The scientific requirements for measurement of the earth's radiative energy budget are presented. Other topics discussed include the observing system concept, solar constant radiometer design, plane flux wide FOV sensor design, fast active cavity theory, fast active cavity design and error analysis, thermopile detectors as an alternative, pre-flight and in-flight calibration plane, system error summary, and interface requirements.

  15. A leakage current-based measurement of the radiation damage in the ATLAS Pixel Detector

    NASA Astrophysics Data System (ADS)

    Gorelov, I. V.

    2015-04-01

    A measurement has been made of the radiation damage incurred by the ATLAS Pixel Detector barrel silicon modules from the beginning of operations through the end of 2012. This translates to hadronic fluence received over the full period of operation at energies up to and including (8 TeV). The measurement is based on a per-module measurement of the silicon sensor leakage current. The results are presented as a function of integrated luminosity and compared to predictions by the Hamburg Model. This information can be used to predict limits on the lifetime of the Pixel Detector due to current, for various operating scenarios.

  16. Radiation damage effects on detectors and eletronic devices in harsh radiation environment

    E-print Network

    Fiore, S

    2015-01-01

    Radiation damage effects represent one of the limits for technologies to be used in harsh radiation environments as space, radiotherapy treatment, high-energy phisics colliders. Different technologies have known tolerances to different radiation fields and should be taken into account to avoid unexpected failures which may lead to unrecoverable damages to scientific missions or patient health.

  17. Electrodrift purification of materials for room temperature radiation detectors

    DOEpatents

    James, R.B.; Van Scyoc, J.M. III; Schlesinger, T.E.

    1997-06-24

    A method of purifying nonmetallic, crystalline semiconducting materials useful for room temperature radiation detecting devices by applying an electric field across the material is disclosed. The present invention discloses a simple technology for producing purified ionic semiconducting materials, in particular PbI{sub 2} and preferably HgI{sub 2}, which produces high yields of purified product, requires minimal handling of the material thereby reducing the possibility of introducing or reintroducing impurities into the material, is easy to control, is highly selective for impurities, retains the stoichiometry of the material and employs neither high temperatures nor hazardous materials such as solvents or liquid metals. An electric field is applied to a bulk sample of the material causing impurities present in the sample to drift in a preferred direction. After all of the impurities have been transported to the ends of the sample the current flowing through the sample, a measure of the rate of transport of mobile impurities, falls to a low, steady state value, at which time the end sections of the sample where the impurities have concentrated are removed leaving a bulk sample of higher purity material. Because the method disclosed here only acts on the electrically active impurities, the stoichiometry of the host material remains substantially unaffected. 4 figs.

  18. Electrodrift purification of materials for room temperature radiation detectors

    DOEpatents

    James, Ralph B. (5420 Lenore Ave., Livermore, Alameda County, CA 94550); Van Scyoc, III, John M. (P.O. Box 93, 65 Main St., Apt. 1, Plainfield, Cumberland County, PA 17081); Schlesinger, Tuviah E. (8 Carleton Dr., Mt. Lebanon, Allegheny County, PA 15243)

    1997-06-24

    A method of purifying nonmetallic, crystalline semiconducting materials useful for room temperature radiation detecting devices by applying an electric field across the material. The present invention discloses a simple technology for producing purified ionic semiconducting materials, in particular PbI.sub.2 and preferably HgI.sub.2, which produces high yields of purified product, requires minimal handling of the material thereby reducing the possibility of introducing or reintroducing impurities into the material, is easy to control, is highly selective for impurities, retains the stoichiometry of the material and employs neither high temperatures nor hazardous materials such as solvents or liquid metals. An electric field is applied to a bulk sample of the material causing impurities present in the sample to drift in a preferred direction. After all of the impurities have been transported to the ends of the sample the current flowing through the sample, a measure of the rate of transport of mobile impurities, falls to a low, steady state value, at which time the end sections of the sample where the impurities have concentrated are removed leaving a bulk sample of higher purity material. Because the method disclosed here only acts on the electrically active impurities, the stoichiometry of the host material remains substantially unaffected.

  19. Current-driven detection of terahertz radiation using a dual-grating-gate plasmonic detector

    SciTech Connect

    Boubanga-Tombet, S. Tanimoto, Y.; Satou, A.; Suemitsu, T.; Otsuji, T.; Wang, Y.; Minamide, H.; Ito, H.; Fateev, D. V.; Popov, V. V.

    2014-06-30

    We report on the detection of terahertz radiation by an on-chip planar asymmetric plasmonic structure in the frequency region above one terahertz. The detector is based on a field-effect transistor that has a dual grating gate structure with an asymmetric unit cell, which provides a geometrical asymmetry within the structure. Biasing the detector with a dc source-to-drain current in the linear region of the current-voltage characteristic introduces an additional asymmetry (electrical asymmetry) that enhances the detector responsivity by more than one order of magnitude (by a factor of 20) as compared with the unbiased case due to the cooperative effect of the geometrical and electrical asymmetries. In addition to the responsivity enhancement, we report a relatively low noise equivalent power and a peculiar non-monotonic dependence of the responsivity on the frequency, which results from the multi-plasmonic-cavity structure of the device.

  20. VHMPID RICH prototype using pressurized C4F8O radiator gas and VUV photon detector

    NASA Astrophysics Data System (ADS)

    Acconcia, T. V.; Agócs, A. G.; Barile, F.; Barnaföldi, G. G.; Bellwied, R.; Bencédi, G.; Bencze, G.; Berényi, D.; Boldizsár, L.; Chattopadhyay, S.; Chinellato, D. D.; Cindolo, F.; Cossyleon, K.; Das, D.; Das, K.; Das-Bose, L.; Dash, A. K.; D`Ambrosio, S.; De Cataldo, G.; De Pasquale, S.; Di Bari, D.; Di Mauro, A.; Futó, E.; Garcia-Solis, E.; Hamar, G.; Harton, A.; Iannone, G.; Jimenez, R. T.; Kim, D. W.; Kim, J. S.; Knospe, A.; Kovács, L.; Lévai, P.; Markert, C.; Martinengo, P.; Molnár, L.; Nappi, E.; Oláh, L.; Pai?, G.; Pastore, C.; Patimo, G.; Patino, M. E.; Peskov, V.; Pinsky, L.; Piuz, F.; Pochybová, S.; Sgura, I.; Sinha, T.; Song, J.; Takahashi, J.; Timmins, A.; Van Beelen, J. B.; Varga, D.; Volpe, G.; Weber, M.; Xaplanteris, L.; Yi, J.; Yoo, I.-K.

    2014-12-01

    A small-size prototype of a new Ring Imaging Cherenkov (RICH) detector using for the first time pressurized C4F8O radiator gas and a photon detector consisting of MWPC equipped with a CsI photocathode has been built and tested at the PS accelerator at CERN. It contained all the functional elements of the detector proposed as Very High Momentum Particle Identification (VHMPID) upgrade for the ALICE experiment at LHC to provide charged hadron track-by-track identification in the momentum range starting from 5 potentially up to 25 GeV/c. In the paper the equipment and its elements are described and some characteristic test results are shown.

  1. The CERN RD50 Collaboration: Development of Radiation-Hard Semiconductor Detectors for Super-LHC

    SciTech Connect

    Macchiolo, Anna

    2005-10-12

    The proposed luminosity upgrade of the Large Hadron Collider (S-LHC) at CERN represents a technological challenge for the vertex detectors of the SLHC experiments since the innermost layers will receive fast hadron fluences up to 1016 cm-2. The CERN RD50 project has been established to explore detector materials and designs that will allow to operate devices up to this limit. Among the different research lines followed by RD50 we report on the development of sensors produced with substrates like Czochralski and epitaxial silicon and on the investigation of the radiation hardness of p-type silicon detectors. Moreover innovative designs like thin, 3D and 3D-STC sensors are under evaluation in the RD50 Collaboration.

  2. Single crystal chemical vapor deposited diamond detectors for intensity-modulated radiation therapy applications

    SciTech Connect

    Rebisz-Pomorska, M.; Tromson, D.; Bergonzo, P.; Isambert, A.; Marczewska, B.

    2009-10-15

    We report here on first intensity-modulated radiation therapy (IMRT) clinical tests performed at the Gustave Roussy Institute in France using one small (0.117 mm{sup 3}) synthetic single crystal diamond detector (SCDD). We report the comparison between the point doses evaluated with our detector, with a PTW semiflex air ionization chamber (0.125 cm{sup 3}) and calculated with the treatment planning system (TPS), respectively. The obtained results show a maximum difference of 2.3% for the diamond detector and of 4.6% for the ionization chamber, as compared with the TPS calculations. These very promising results show the potentiality of chemical vapor deposited SCDD for dosimetry of IMRT fields and opens up the field for diamond dosimeters toward novel applications such as very small beam monitoring.

  3. A high rate transition radiation detector for particle identification in a hadron beam

    SciTech Connect

    Errede, D.; Sheaff, M.; Fenker, H.; Mantsch, P.

    1989-08-01

    A Transition Radiation Detector (TRD) was built for the purpose of tagging beam particles in a high rate (/approximately/2 MHz) 250 GeV/c hadron beam during data taking for Experiment 769 at Fermilab. The availability of a good ''tool kit'', including a Monte Carlo program which could reliably predict the detector performance, made it possible to design and build the TRD in approximately one year. Pion or proton samples, each with a small contamination due to the other, could be selected with high efficiency by making cuts on the number of planes of the TRD registering hits for each incident beam particle. The detector is expected to work well to separate kaons from pions in the 500 GeV/c negative beam for E791. 15 refs., 8 figs., 1 tab.

  4. Micro-Fabricated Solid-State Radiation Detectors for Active Personal Dosimetry

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D.; Wrbanek, Susan Y.; Fralick, Gustave C.; Chen, Liang-Yu

    2007-01-01

    Active radiation dosimetry is important to human health and equipment functionality for space applications outside the protective environment of a space station or vehicle. This is especially true for long duration missions to the moon, where the lack of a magnetic field offers no protection from space radiation to those on extravehicular activities. In order to improve functionality, durability and reliability of radiation dosimeters for future NASA lunar missions, single crystal silicon carbide devices and scintillating fiber detectors are currently being investigated for applications in advanced extravehicular systems. For many years, NASA Glenn Research Center has led significant efforts in silicon carbide semiconductor technology research and instrumentation research for sensor applications under extreme conditions. This report summarizes the technical progress and accomplishments toward characterization of radiation-sensing components for the recommendation of their fitness for advanced dosimetry development.

  5. Comparison of Direct Normal Irradiance Derived from Silicon and Thermopile Global Hemispherical Radiation Detectors: Preprint

    SciTech Connect

    Myers, D. R.

    2010-01-01

    Concentrating solar applications utilize direct normal irradiance (DNI) radiation, a measurement rarely available. The solar concentrator industry has begun to deploy numerous measurement stations to prospect for suitable system deployment sites. Rotating shadowband radiometers (RSR) using silicon photodiodes as detectors are typically deployed. This paper compares direct beam estimates from RSR to a total hemispherical measuring radiometer (SPN1) multiple fast thermopiles. These detectors simultaneously measure total and diffuse radiation from which DNI can be computed. Both the SPN1 and RSR-derived DNI are compared to DNI measured with thermopile pyrheliometers. Our comparison shows that the SPN1 radiometer DNI estimated uncertainty is somewhat greater than, and on the same order as, the RSR DNI estimates for DNI magnitudes useful to concentrator technologies.

  6. Infrared response measurements on radiation-damaged Si/Li/ detectors.

    NASA Technical Reports Server (NTRS)

    Sher, A. H.; Liu, Y. M.; Keery, W. J.

    1972-01-01

    The improved infrared response (IRR) technique has been used to qualitatively compare radiation effects on Si(Li) detectors with energy levels reported for silicon in the literature. Measurements have been made on five commercial silicon detectors and one fabricated in-house, both before and after irradiation with fast neutrons, 1.9-MeV protons, and 1.6-MeV electrons. Effects dependent upon the extent of radiation damage have been observed. It seems likely that the photo-EMF, or photo-voltage, effect is the basic mechanism for the observation of IRR in p-i-n diodes with a wide i-region. Experimental characteristics of the IRR measurement are in agreement with those of the photovoltage effect.

  7. Simulation of active-edge pixelated CdTe radiation detectors

    NASA Astrophysics Data System (ADS)

    Duarte, D. D.; Lipp, J. D.; Schneider, A.; Seller, P.; Veale, M. C.; Wilson, M. D.; Baker, M. A.; Sellin, P. J.

    2016-01-01

    The edge surfaces of single crystal CdTe play an important role in the electronic properties and performance of this material as an X-ray and ?-ray radiation detector. Edge effects have previously been reported to reduce the spectroscopic performance of the edge pixels in pixelated CdTe radiation detectors without guard bands. A novel Technology Computer Aided Design (TCAD) model based on experimental data has been developed to investigate these effects. The results presented in this paper show how localized low resistivity surfaces modify the internal electric field of CdTe creating potential wells. These result in a reduction of charge collection efficiency of the edge pixels, which compares well with experimental data.

  8. Signal and noise of Diamond Pixel Detectors at High Radiation Fluences

    E-print Network

    Jieh-Wen Tsung; Miroslav Havranek; Fabian Hügging; Harris Kagan; Hans Krüger; Norbert Wermes

    2012-08-13

    CVD diamond is an attractive material option for LHC vertex detectors because of its strong radiation-hardness causal to its large band gap and strong lattice. In particular, pixel detectors operating close to the interaction point profit from tiny leakage currents and small pixel capacitances of diamond resulting in low noise figures when compared to silicon. On the other hand, the charge signal from traversing high energy particles is smaller in diamond than in silicon by a factor of about 2.2. Therefore, a quantitative determination of the signal-to-noise ratio (S/N) of diamond in comparison with silicon at fluences in excess of 10$^{15}$ n$_{eq}$ cm$^{-2}$, which are expected for the LHC upgrade, is important. Based on measurements of irradiated diamond sensors and the FE-I4 pixel readout chip design, we determine the signal and the noise of diamond pixel detectors irradiated with high particle fluences. To characterize the effect of the radiation damage on the materials and the signal decrease, the change of the mean free path $\\lambda_{e/h}$ of the charge carriers is determined as a function of irradiation fluence. We make use of the FE-I4 pixel chip developed for ATLAS upgrades to realistically estimate the expected noise figures: the expected leakage current at a given fluence is taken from calibrated calculations and the pixel capacitance is measured using a purposely developed chip (PixCap). We compare the resulting S/N figures with those for planar silicon pixel detectors using published charge loss measurements and the same extrapolation methods as for diamond. It is shown that the expected S/N of a diamond pixel detector with pixel pitches typical for LHC, exceeds that of planar silicon pixels at fluences beyond 10$^{15}$ particles cm$^{-2}$, the exact value only depending on the maximum operation voltage assumed for irradiated silicon pixel detectors.

  9. Signal and noise of diamond pixel detectors at high radiation fluences

    NASA Astrophysics Data System (ADS)

    Tsung, J.-W.; Havranek, M.; Hügging, F.; Kagan, H.; Krüger, H.; Wermes, N.

    2012-09-01

    CVD diamond is an attractive material option for LHC vertex detectors mainly because of its strong radiation-hardness causal to its large band gap and strong lattice. In particular, pixel detectors operating close to the interaction point profit from tiny leakage currents and small pixel capacitances of diamond resulting in low noise figures when compared to silicon. On the other hand, the charge signal from traversing high energy particles is smaller in diamond than in silicon by a factor of about 2.2. Therefore, a quantitative determination of the signal-to-noise ratio (S/N) of diamond in comparison with silicon at fluences in excess of 1015 neq cm-2, which are expected for the LHC upgrade, is important. Based on measurements of irradiated diamond sensors and the FE-I4 pixel readout chip design and performance, we determine the signal and the noise of diamond pixel detectors irradiated with high particle fluences. To characterize the effect of the radiation damage on the materials and the signal decrease, the change of the mean free path ?e/h of the charge carriers is determined as a function of irradiation fluence. We make use of the FE-I4 pixel chip developed for ATLAS upgrades to realistically estimate the expected noise figures: the expected leakage current at a given fluence is taken from calibrated calculations and the pixel capacitance is measured using a purposely developed chip (PixCap). We compare the resulting S/N figures with those for planar silicon pixel detectors using published charge loss measurements and the same extrapolation methods as for diamond. It is shown that the expected S/N of a diamond pixel detector with pixel pitches typical for LHC, exceeds that of planar silicon pixels at fluences beyond 1015 particles cm-2, the exact value only depending on the maximum operation voltage assumed for irradiated silicon pixel detectors.

  10. Radiation detector using a bulk high T[sub c] superconductor

    DOEpatents

    Artuso, J.F.; Franks, L.A.; Hull, K.L.; Symko, O.G.

    1993-12-07

    A radiation detector is provided, wherein a bulk high T[sub c] superconducting sample is placed in a magnetic field and maintained at a superconducting temperature. Photons of incident radiation will cause localized heating in superconducting loops of the sample destroying trapped flux and redistributing the fluxons, and reducing the critical current of the loops. Subsequent cooling of the sample in the magnetic field will cause trapped flux redistributed Abrikosov fluxons and trapped Josephson fluxons. The destruction and trapping of the fluxons causes changes in the magnetization of the sample inducing currents in opposite directions in a pickup coil which is coupled by an input coil to an rf SQUID. 4 figures.

  11. Particularities of IR-radiation absorbing in fine polyimide structures and microbolometer detector on their base

    NASA Astrophysics Data System (ADS)

    Zhukov, A. A.; Zdobnikov, A. E.; Klemin, S. N.; Tarasov, Victor V.; Filatov, L. A.; Chetverov, Yu. S.

    2003-03-01

    The absorption of IR-radiation 200-4000 cm-1 range of 0,65-1,9 micron thick polyimide thin-films with such functional coverings as titanium, silicon nitride, aluminium was investigated. The 1,3-1,4 micron thick polyimide structure have 85% absorption of IR-radiation of 720-1250 cm-1 range. On the base of the developed polyimide thin-film technology linear micro bolometric array detectors was fabricated and investigated. Calculated value of the linear micro bolometer array detectivity is 4×107 cm Hz1/2W-1.

  12. X-ray photoemission analysis of chemically modified TlBr surfaces for improved radiation detectors

    NASA Astrophysics Data System (ADS)

    Nelson, A. J.; Voss, L. F.; Beck, P. R.; Graff, R. T.; Conway, A. M.; Nikolic, R. J.; Payne, S. A.; Lee, J.-S.; Kim, H.; Cirignano, L.; Shah, K.

    2013-04-01

    Device-grade TlBr was subjected to various chemical treatments used in room temperature radiation detector fabrication to determine the resulting surface composition and electronic structure. As-polished TlBr was treated separately with HCl, SOCl2, Br:MeOH, and HF solutions. High-resolution photoemission measurements on the valence band electronic structure and Tl 4f, Br 3d, Cl 2p, and S 2p core lines were used to evaluate surface chemistry and shallow heterojunction formation. Surface chemistry and valence band electronic structure were correlated with the goal of optimizing the long-term stability and radiation response.

  13. Pattern recognition of tracks induced by individual quanta of ionizing radiation in Medipix2 silicon detector

    NASA Astrophysics Data System (ADS)

    Holy, T.; Heijne, E.; Jakubek, J.; Pospisil, S.; Uher, J.; Vykydal, Z.

    2008-06-01

    Medipix2 is a semiconductor pixel detector (256×256 pixels, 55×55 ?m 2 each) which can count individual quanta of radiation. The detector will respond differently for different types of radiation. If the acquisition time is short enough with respect to radiation intensity, one can see characteristic tracks of individual quanta in an image taken (e.g., curved lines for electrons, round shaped clusters for alpha particles, heavy ions and slow neutrons, cone shapes for fast neutrons, simple dots for low energy X-rays, etc.). For effective visualization of neutrons, the device has to be equipped by corresponding neutron converter, which converts neutrons to heavy charged particles. By analyzing these patterns, in this so-called "tracking mode" of operation, it is possible to distinguish individual tracks and classify them into predefined categories. For each "cluster" detected, the features (such as parameters describing the shape and energy deposition estimation) can be extracted and used to distinguish radiation type. The energy deposited can be estimated by using calibration measurements with different types of radiation and variation of the discrimination threshold.

  14. Parasitic Effects Affecting Responsivity of Sub-THz Radiation Detector Built of a MOSFET

    NASA Astrophysics Data System (ADS)

    Kopyt, P.; Salski, B.; Marczewski, J.; Zagrajek, P.; Lusakowski, J.

    2015-11-01

    In this paper, an analysis of parasitic elements that are found in all typical metal-oxide-semiconductor field-effect transistors (MOSFETs) has been performed from a viewpoint of a designer of sub-THz radiation detectors. A simplified model of the extrinsic MOSFET device has been proposed. Typical values of its parameters have been assumed. The authors have also built a model of the MOSFET's channel (intrinsic device) employing the standard transmission line approach and defining a Z-matrix of the circuit in order to facilitate its integration with the parasitic elements. The full effective circuit model of the MOSFET has been employed to analyze the behavior of the detector when subjected to sub-THz radiation delivered through the Gate and Source pads. Finally, predictions of the responsivity of an example detector built of a typical MOSFET integrated with a patch antenna fabricated on a 40-?m-thick silicon membrane have been compared with measurements of several structures employing MOSFETs of various channel widths. Good agreement between the predictions and the measurements has been demonstrated, which indicates that despite its simplicity, the presented model can significantly help to better understand operation of MOSFET-based detectors and also to use the existing silicon-based manufacturing processes.

  15. The iQID camera: An ionizing-radiation quantum imaging detector

    PubMed Central

    Miller, Brian W.; Gregory, Stephanie J.; Fuller, Erin S.; Barrett, Harrison H.; Barber, H. Bradford; Furenlid, Lars R.

    2015-01-01

    We have developed and tested a novel, ionizing-radiation Quantum Imaging Detector (iQID). This scintillation-based detector was originally developed as a high-resolution gamma-ray imager, called BazookaSPECT, for use in single-photon emission computed tomography (SPECT). Recently, we have investigated the detector’s response and imaging potential with other forms of ionizing radiation including alpha, neutron, beta, and fission fragment particles. The confirmed response to this broad range of ionizing radiation has prompted its new title. The principle operation of the iQID camera involves coupling a scintillator to an image intensifier. The scintillation light generated by particle interactions is optically amplified by the intensifier and then re-imaged onto a CCD/CMOS camera sensor. The intensifier provides sufficient optical gain that practically any CCD/CMOS camera can be used to image ionizing radiation. The spatial location and energy of individual particles are estimated on an event-by-event basis in real time using image analysis algorithms on high-performance graphics processing hardware. Distinguishing features of the iQID camera include portability, large active areas, excellent detection efficiency for charged particles, and high spatial resolution (tens of microns). Although modest, iQID has energy resolution that is sufficient to discriminate between particles. Additionally, spatial features of individual events can be used for particle discrimination. An important iQID imaging application that has recently been developed is real-time, single-particle digital autoradiography. We present the latest results and discuss potential applications. PMID:26166921

  16. The prototype of a detector for monitoring the cosmic radiation neutron flux on ground

    SciTech Connect

    Lelis Goncalez, Odair; Federico, Claudio Antonio; Mendes Prado, Adriane Cristina; Galhardo Vaz, Rafael; Tizziani Pazzianotto, Mauricio

    2013-05-06

    This work presents a comparison between the results of experimental tests and Monte Carlo simulations of the efficiency of a detector prototype for on-ground monitoring the cosmic radiation neutron flux. The experimental tests were made using one conventional {sup 241}Am-Be neutron source in several incidence angles and the results were compared to that ones obtained with a Monte Carlo simulation made with MCNPX Code.

  17. High-speed, multi-channel detector readout electronics for fast radiation detectors

    SciTech Connect

    Hennig, Wolfgang

    2012-06-22

    In this project, we are developing a high speed digital spectrometer that a) captures detector waveforms at rates up to 500 MSPS b) has upgraded event data acquisition with additional data buffers for zero dead time operation c) moves energy calculations to the FPGA to increase spectrometer throughput in fast scintillator applications d) uses a streamlined architecture and high speed data interface for even faster readout to the host PC These features are in addition to the standard functions in our existing spectrometers such as digitization, programmable trigger and energy filters, pileup inspection, data acquisition with energy and time stamps, MCA histograms, and run statistics. In Phase I, we upgraded one of our existing spectrometer designs to demonstrate the key principle of fast waveform capture using a 500 MSPS, 12 bit ADC and a Xilinx Virtex-4 FPGA. This upgraded spectrometer, named P500, performed well in initial tests of energy resolution, pulse shape analysis, and timing measurements, thus achieving item (a) above. In Phase II, we are revising the P500 to build a commercial prototype with the improvements listed in items (b)-(d). As described in the previous report, two devices were built to pursue this goal, named the Pixie-500 and the Pixie-500 Express. The Pixie-500 has only minor improvements from the Phase I prototype and is intended as an early commercial product (its production and part of its development were funded outside the SBIR). It also allows testing of the ADC performance in real applications.The Pixie-500 Express (or Pixie-500e) includes all of the improvements (b)-(d). At the end of Phase II of the project, we have tested and debugged the hardware, firmware and software of the Pixie-500 Express prototype boards delivered 12/3/2010. This proved substantially more complex than anticipated. At the time of writing, all hardware bugs have been fixed, the PCI Express interface is working, the SDRAM has been successfully tested and the SHARC DSP has been booted with preliminary code. All new ICs and circuitry on the prototype are working properly, however some of the planned firmware and software functions have not yet been completely implemented and debugged. Overall, due to the unanticipated complexity of the PCI Express interface, some aspects of the project could not be completed with the time and funds available in Phase II. These aspects will be completed in self-funded Phase III.

  18. Reconstruction of charged particle fluxes detected by the Radiation Assessment Detector onboard of MSL

    NASA Astrophysics Data System (ADS)

    Guo, J.; Wimmer-Schweingruber, R. F.; Hassler, D.; Zeitlin, C. J.; Ehresmann, B.; Kohler, J.; Boehm, E.; Appel, J. K.; Lohf, H.; Boettcher, S.; Burmeister, S.; Rafkin, S. C.; Kharytonov, A.; Martin-Garcia, C.; Matthiae, D.; Reitz, G.

    2013-12-01

    One of the main science objectives of the Mars Science Laboratory (MSL) is to help planning future human exploration to Mars by constraining the radiation environment during the cruise phase and on the planet's surface. During the 253-day, 560 million km cruise to Mars, the Radiation Assessment Detector, RAD made detailed measurements of the energy spectrum deposited by energetic particles from space and scattered within the spacecraft. Two types of radiation pose potential health risks to astronauts in deep space: a prolonged low-dose exposure to Galactic Cosmic Rays (GCRs) and short-term exposures to the Solar Energetic Particles (SEPs). On the surface of Mars such energetic particles penetrate through its thin atmosphere and generate secondary particles that can also result harms to humans. In order to interpret the energetic charged particle flux coming into the detector, we have developed the Detector Response Function (DRF) using GEANT 4 simulations and employed a Maximum likelihood inversion technique to invert the detected energy spectrum. This method has been applied to RAD detection of GCRs and secondary charged particles on the Martian surface, giving us an unique insight into their energy fluxes. The spectra of the stopping particle fluxes (hydrogen and helium) are also directly obtained from RAD observations and compared with the inversion results.

  19. Towards thin-film self-powered radiation detectors employing disparate conductive layers

    NASA Astrophysics Data System (ADS)

    Brivio, D.; Sajo, E.; Zygmanski, P.

    2015-06-01

    A new class of self-powered thin film radiation detectors is experimentally explored via their IV-curve characteristics. These detectors are parallel-plane microstructures composed of disparate atomic number (Z) thin-film electrodes separated by air gaps. Large radiation-induced electron currents (RIC) are observed for zero external voltage bias. Compared to ionization chambers (composed of macroscopic non-disparate low-Z electrodes), this anomalous behavior is due to two independent effects: traversal of fast electrons leaking from the high-Z cathodes and the auto-collection of ionization electrons from the air gap due to the presence of contact potential. The zero voltage current reaches up to 80% of the saturation current measured for non-zero bias voltages. The magnitude of saturation currents increases with the total anode and cathode atomic numbers. The stopping potentials (i.e., external voltage bias resulting in zero RIC current) correspond to the differences in the electrodes’ work functions (the contact potential) modified by the contributions from the fast electron current formed by the leaking electrons. These features make the thin film detector attractive for applications in x-ray medical or industrial imaging, dosimetry and radiation protection.

  20. The ALICE Transition Radiation Detector: status and perspectives for Run II

    E-print Network

    Klein, Jochen

    2016-01-01

    The ALICE Transition Radiation Detector contributes to the tracking, particle identification, and triggering capabilities of the experiment. It is composed of six layers of multi-wire proportional chambers, each of which is preceded by a radiator and a Xe/CO$_2$-filled drift volume. The signal is sampled in timebins of 100~ns over the drift length which allows for the reconstruction of chamber-wise track segments, both online and offline. The particle identification is based on the specific energy loss of charged particles and additional transition radiation photons, the latter being a signature for electrons. The detector is segmented into 18 sectors, of which 13 were installed in Run I. The TRD was included in data taking since the LHC start-up and was successfully used for electron identification and triggering. During the Long Shutdown 1, the detector was completed and now covers the full azimuthal acceptance. Furthermore, the readout and trigger components were upgraded. When data taking was started for ...

  1. High-energy proton radiation damage of high-purity germanium detectors

    NASA Technical Reports Server (NTRS)

    Pehl, R. H.; Varnell, L. S.; Metzger, A. E.

    1978-01-01

    Quantitative studies of radiation damage in high-purity germanium gamma-ray detectors due to high-energy charged particles have been carried out; two 1.0 cm thick planar detectors were irradiated by 6 GeV/c protons. Under proton bombardment, degradation in the energy resolution was found to begin below 7 x 10 to the 7th protons/sq cm and increased proportionately in both detectors until the experiment was terminated at a total flux of 5.7 x 10 to the 8th protons/sq cm, equivalent to about a six year exposure to cosmic-ray protons in space. At the end of the irradiation, the FWHM resolution measured at 1332 keV stood at 8.5 and 13.6 keV, with both detectors of only marginal utility as a spectrometer due to the severe tailing caused by charge trapping. Annealing these detectors after proton damage was found to be much easier than after neutron damage.

  2. Control of electric field in CdZnTe radiation detectors by above-bandgap light

    SciTech Connect

    Franc, J.; D?di?, V.; Rejhon, M.; Zázvorka, J.; Praus, P.; Touš, J.; Sellin, P. J.

    2015-04-28

    We have studied the possibility of above bandgap light induced depolarization of CdZnTe planar radiation detector operating under high flux of X-rays by Pockels effect measurements. In this contribution, we show a similar influence of X-rays at 80 kVp and LED with a wavelength of 910?nm irradiating the cathode on polarization of the detector due to an accumulation of a positive space charge of trapped photo-generated holes. We have observed the depolarization of the detector under simultaneous cathode-site illumination with excitation LED at 910?nm and depolarization above bandgap LED at 640?nm caused by trapping of drifting photo-generated electrons. Although the detector current is quite high during this depolarization, we have observed that it decreases relatively fast to its initial value after switching off the depolarizing light. In order to get detailed information about physical processes present during polarization and depolarization and, moreover, about associated deep levels, we have performed the Pockels effect infrared spectral scanning measurements of the detector without illumination and under illumination in polarized and optically depolarized states.

  3. Opto-electrical characterization and X-ray mapping of large-volume cadmium zinc telluride radiation detectors

    SciTech Connect

    Yang, G.; Bolotnikov, A.E.; Camarda, G.S.; Cui, Y.; Hossain, A.; Yao, H.W.; Kim, K.; and James, R.B.

    2009-04-13

    Large-volume cadmium zinc telluride (CZT) radiation detectors would greatly improve radiation detection capabilities and, therefore, attract extensive scientific and commercial interests. CZT crystals with volumes as large as hundreds of centimeters can be achieved today due to improvements in the crystal growth technology. However, the poor performance of large-volume CZT detectors is still a challenging problem affecting the commercialization of CZT detectors and imaging arrays. We have employed Pockels effect measurements and synchrotron X-ray mapping techniques to investigate the performance-limiting factors for large-volume CZT detectors. Experimental results with the above characterization methods reveal the non-uniform distribution of internal electric field of large-volume CZT detectors, which help us to better understand the responsible mechanism for the insufficient carrier collection in large-volume CZT detectors.

  4. Radiation measurement platform for balloon flights based on the TriTel silicon detector telescope

    NASA Astrophysics Data System (ADS)

    Zabori, Balazs; Hirn, Attila; Pazmandi, Tamas; Apathy, Istvan; Szanto, Peter; Deme, Sandor

    Several measurements have been performed on the cosmic radiation field from the surface of the Earth up to the maximum altitudes of research airplanes. However the cosmic radiation field is not well known between 15 km and 30 km. Our experiment idea based on to study the radiation environment in the stratosphere. The main technical goals of our experiment were to test at first time the TriTel 3D silicon detector telescope system for future ISS missons and to develop a balloon technology platform for advanced cosmic radiation and dosimetric measurements. The main scientific goals were to give an assessment of the cosmic radiation field at the altitude of the BEXUS balloons, to use the TriTel system to determine dosimetric and radiation quantities during the ballon flight and to intercompare the TriTel and Pille results to provide a correction factor definition method for the Pille ISS measurements. To fulfil the scientific and technological objectives several different dosimeter systems were included in the experiment: an advanced version of the TriTel silicon detector telescope, Geiger-Müller counters, Pille passive thermoluminescent dosimeters and Solid State Nuclear Track Detectors. The experiment was built by students from Hungarian universities and flew on board the BEXUS stratospheric balloon in Northern Sweden (from ESRANGE Space Center). The float altitude was approximately 28.6 km and the total flight time was about 4 hours. The active instruments measured in real time and the ground team received the collected data continuously during the mission. The main technical goals were received since the operation of the TriTel experienced no failures and the experiment worked as it expected. This paper presents the scientific goals and results. From the TriTel measurements the deposited energy spectra, the Linear Energy Transfer spectra, the average quality factor of the cosmic radiation as well as the absorbed dose and the dose equivalent were determined for the three axis. TriTel data evaluation and error estimations were studied in details. The evaluated deposited energy spectra measured with the improved TriTel instrument were compared with the count rates measured with the GM counters to calibrate them for dose rate in the cosmic radiation field at the altitude of the stratospheric balloons. From the SSNTD results the contribution of thermal neutrons was determined. In the frame of the TriTel and Pille intercomparison a correction factor calculation method was determined for future ISS data evaluation. The results will be used in the future scientific data evaluation in case of the ISS measurements. As a future outlook a short overview will be given about planned rocket radiation experiments.

  5. Development of an Alpha/Beta/Gamma Phoswich-Based Radiation Detector for Nuclear Waste Stream Cleanup Processes

    SciTech Connect

    William H. Miller; Tushar Ghosh

    2004-03-10

    The goal of this research is to design, build and test a phoswich-based radiation detector for simultaneously monitoring all radioactive components in the effluent resulting from the cleanup of nuclear waste

  6. Collisional, radiative and total electron interaction in compound semiconductor detectors and solid state nuclear track detectors: effective atomic number and electron density.

    PubMed

    Kurudirek, Murat; Kurudirek, Sinem V

    2015-05-01

    Effective atomic numbers, Zeff and electron densities, Ne are widely used for characterization of interaction processes in radiation related studies. A variety of detectors are employed to detect different types of radiations i.e. photons and charged particles. In the present work, some compound semiconductor detectors (CSCD) and solid state nuclear track detectors (SSNTD) were investigated with respect to the partial as well as total electron interactions. Zeff and Ne of the given detectors were calculated for collisional, radiative and total electron interactions in the kinetic energy region 10keV-1GeV. Maximum values of Zeff and Ne were observed at higher kinetic energies of electrons. Significant variations in Zeff and Ne up to ?20-25% were noticed for the detectors, GaN, ZnO, Amber and CR-39 for total electron interaction. Moreover, the obtained Zeff and Ne for electrons were compared to those obtained for photons in the entire energy region. Significant variations in Zeff were also noted not only for photons (up to ?40% for GaN) but also between photons and electrons (up to ?60% for CR-39) especially at lower energies. Except for the lower energies, Zeff and Ne keep more or less constant values for the given materials. The energy regions where Zeff and Ne keep constant clearly show the availability of using these parameters for characterization of the materials with respect to the radiation interaction processes. PMID:25702888

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

    SciTech Connect

    Han, Hetong; School of Nuclear Science and Technology, Xi'an Jiaotong University, XJTU, Xi'an 710049, Shaanxi ; 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.

  8. The iQID camera: An ionizing-radiation quantum imaging detector

    NASA Astrophysics Data System (ADS)

    Miller, Brian W.; Gregory, Stephanie J.; Fuller, Erin S.; Barrett, Harrison H.; Bradford Barber, H.; Furenlid, Lars R.

    2014-12-01

    We have developed and tested a novel, ionizing-radiation Quantum Imaging Detector (iQID). This scintillation-based detector was originally developed as a high-resolution gamma-ray imager, called BazookaSPECT, for use in single-photon emission computed tomography (SPECT). Recently, we have investigated the detector's response and imaging potential with other forms of ionizing radiation including alpha, neutron, beta, and fission fragment particles. The confirmed response to this broad range of ionizing radiation has prompted its new title. The principle operation of the iQID camera involves coupling a scintillator to an image intensifier. The scintillation light generated by particle interactions is optically amplified by the intensifier and then re-imaged onto a CCD/CMOS camera sensor. The intensifier provides sufficient optical gain that practically any CCD/CMOS camera can be used to image ionizing radiation. The spatial location and energy of individual particles are estimated on an event-by-event basis in real time using image analysis algorithms on high-performance graphics processing hardware. Distinguishing features of the iQID camera include portability, large active areas, excellent detection efficiency for charged particles, and high spatial resolution (tens of microns). Although modest, iQID has energy resolution that is sufficient to discriminate between particles. Additionally, spatial features of individual events can be used for particle discrimination. An important iQID imaging application that has recently been developed is real-time, single-particle digital autoradiography. We present the latest results and discuss potential applications.

  9. Investigation of epitaxial silicon layers as a material for radiation hardened silicon detectors

    SciTech Connect

    Li, Z.; Eremin, V.; Ilyashenko, I.; Ivanov, A.; Verbitskaya, E.; CERN RD-48 ROSE Collaboration

    1997-12-01

    Epitaxial grown thick layers ({ge} 100 micrometers) of high resistivity silicon (Epi-Si) have been investigated as a possible candidate of radiation hardened material for detectors for high-energy physics. As grown Epi-Si layers contain high concentration (up to 2 {times} 10{sup 12} cm{sup {minus}3}) of deep levels compared with that in standard high resistivity bulk Si. After irradiation of test diodes by protons (E{sub p} = 24 GeV) with a fluence of 1.5 {times} 10{sup 11} cm{sup {minus}2}, no additional radiation induced deep traps have been detected. A reasonable explanation is that there is a sink of primary radiation induced defects (interstitial and vacancies), possibly by as-grown defects, in epitaxial layers. The ``sinking`` process, however, becomes non-effective at high radiation fluences (10{sup 14} cm{sup {minus}2}) due to saturation of epitaxial defects by high concentration of radiation induced ones. As a result, at neutron fluence of 1 {times} 10{sup 14} cm{sup {minus}2} the deep level spectrum corresponds to well-known spectrum of radiation induced defects in high resistivity bulk Si. The net effective concentration in the space charge region equals to 3 {times} 10{sup 12} cm{sup {minus}3} after 3 months of room temperature storage and reveals similar annealing behavior for epitaxial as compared to bulk silicon.

  10. Light scattering apparatus and method for determining radiation exposure to plastic detectors

    DOEpatents

    Hermes, Robert E. (White Rock, NM)

    2002-01-01

    An improved system and method of analyzing cumulative radiation exposure registered as pits on track etch foils of radiation dosimeters. The light scattering apparatus and method of the present invention increases the speed of analysis while it also provides the ability to analyze exposure levels beyond that which may be properly measured with conventional techniques. Dosimeters often contain small plastic sheets that register accumulated damage when exposed to a radiation source. When the plastic sheet from the dosimeter is chemically etched, a track etch foil is produced wherein pits or holes are created in the plastic. The number of these pits, or holes, per unit of area (pit density) correspond to the amount of cumulative radiation exposure which is being optically measured by the apparatus. To measure the cumulative radiation exposure of a track etch foil a high intensity collimated beam is passed through foil such that the pits and holes within the track etch foil cause a portion of the impinging light beam to become scattered upon exit. The scattered light is focused with a lens, while the primary collimated light beam (unscattered light) is blocked. The scattered light is focused by the lens onto an optical detector capable of registering the optical power of the scattered light which corresponds to the cumulative radiation to which the track etch foil has been exposed.

  11. Signal and noise analysis of a-Si:H radiation detector-amplifier system

    SciTech Connect

    Cho, Gyuseong

    1992-03-01

    Hydrogenated amorphous silicon (a-Si:H) has potential advantages in making radiation detectors for many applications because of its deposition capability on a large-area substrate and its high radiation resistance. Position-sensitive radiation detectors can be made out of a 1d strip or a 2-d pixel array of a Si:H pin diodes. In addition, signal processing electronics can be made by thin-film transistors on the same substrate. The calculated radiation signal, based on a simple charge collection model agreed well with results from various wave length light sources and 1 MeV beta particles on sample diodes. The total noise of the detection system was analyzed into (a) shot noise and (b) 1/f noise from a detector diode, and (c) thermal noise and (d) 1/f noise from the frontend TFT of a charge-sensitive preamplifier. the effective noise charge calculated by convoluting these noise power spectra with the transfer function of a CR-RC shaping amplifier showed a good agreement with the direct measurements of noise charge. The derived equations of signal and noise charge can be used to design an a-Si:H pixel detector amplifier system optimally. Signals from a pixel can be readout using switching TFTs, or diodes. Prototype tests of a double-diode readout scheme showed that the storage time and the readout time are limited by the resistances of the reverse-biased pixel diode and the forward biased switching diodes respectively. A prototype charge-sensitive amplifier was made using poly-Si TFTs to test the feasibility of making pixel-level amplifiers which would be required in small-signal detection. The measured overall gain-bandwidth product was {approximately}400 MHz and the noise charge {approximately}1000 electrons at a 1 {mu}sec shaping time. When the amplifier is connected to a pixel detector of capacitance 0.2 pF, it would give a charge-to-voltage gain of {approximately}0.02 mV/electron with a pulse rise time less than 100 nsec and a dynamic range of 48 dB.

  12. Neutron measurements with Time-Resolved Event-Counting Optical Radiation (TRECOR) detector

    NASA Astrophysics Data System (ADS)

    Brandis, M.; Vartsky, D.; Dangendorf, V.; Bromberger, B.; Bar, D.; Goldberg, M. B.; Tittelmeier, K.; Friedman, E.; Czasch, A.; Mardor, I.; Mor, I.; Weierganz, M.

    2012-04-01

    Results are presented from the latest experiment with a new neutron/gamma detector, a Time-Resolved, Event-Counting Optical Radiation (TRECOR) detector. It is composed of a scintillating fiber-screen converter, bending mirror, lens and Event-Counting Image Intensifier (ECII), capable of specifying the position and time-of-flight of each event. TRECOR is designated for a multipurpose integrated system that will detect Special Nuclear Materials (SNM) and explosives in cargo. Explosives are detected by Fast-Neutron Resonance Radiography, and SNM by Dual Discrete-Energy gamma-Radiography. Neutrons and gamma-rays are both produced in the 11B(d,n+?)12C reaction. The two detection modes can be implemented simultaneously in TRECOR, using two adjacent radiation converters that share a common optical readout. In the present experiment the neutron detection mode was studied, using a plastic scintillator converter. The measurements were performed at the PTB cyclotron, using the 9Be(d,n) neutron spectrum obtained from a thick Be-target at Ed ~ 13 MeV\\@. The basic characteristics of this detector were investigated, including the Contrast Transfer Function (CTF), Point Spread Function (PSF) and elemental discrimination capability.

  13. Down-conversion detection in 300 GHz radiation using Glow Discharge Detector (GDD)

    NASA Astrophysics Data System (ADS)

    Aharon Akram, Avihai; Kopeika, N. S.; Abramovich, A.; Slavin, B.

    2012-05-01

    A miniature neon indicator lamp, also known as a Glow Discharge Detector (GDD), costing about 50 cents was found to be an excellent room temperature THz radiation detector. Down conversion detection using the GDD for 300 GHz radiation is demonstrated in this study. Previous results with the GDD at 10 GHz showed 40 times better sensitivity using down conversion detection compared to direct detection. Preliminary results at 300 GHz showed better sensitivity by at least one order of magnitude using down conversion compared to direct detection. This can be improved by increasing reference beam power. In order to realize a down-conversion set up we used two synchronized THz sources based on RF multipliers. The first is a 300 GHz source and the second is a 300 GHz+?f source, where ?f stands for the frequency difference between the two sources. Using a beam splitter configuration we combine the two frequencies for ?f=20 kHz and directed them to the GDD. Due to the unique detection mechanism of the GDD and its linear response, the difference frequency ?f was detected by the electronics circuits. We anticipate significant improvement in detection performance for higher values of ?f due to lower detector noise at higher frequencies.

  14. New BNL 3D-Trench Electrode Si Detectors for Radiation Hard Detectors for sLHC and for X-ray Applications

    SciTech Connect

    Li Z.

    2011-05-11

    A new international-patent-pending (PCT/US2010/52887) detector type, named here as 3D-Trench electrode Si detectors, is proposed in this work. In this new 3D electrode configuration, one or both types of electrodes are etched as trenches deep into the Si (fully penetrating with SOI or supporting wafer, or non-fully penetrating into 50-90% of the thickness), instead of columns as in the conventional ('standard') 3D electrode Si detectors. With trench etched electrodes, the electric field in the new 3D electrode detectors are well defined without low or zero field regions. Except near both surfaces of the detector, the electric field in the concentric type 3D-Trench electrode Si detectors is nearly radial with little or no angular dependence in the circular and hexangular (concentric-type) pixel cell geometries. In the case of parallel plate 3D trench pixels, the field is nearly linear (like the planar 2D electrode detectors), with simple and well-defined boundary conditions. Since each pixel cell in a 3D-Trench electrode detector is isolated from others by highly doped trenches, it is an electrically independent cell. Therefore, an alternative name 'Independent Coaxial Detector Array', or ICDA, is assigned to an array of 3D-Trench electrode detectors. The electric field in the detector can be reduced by a factor of nearly 10 with an optimal 3D-Trench configuration where the junction is on the surrounding trench side. The full depletion voltage in this optimal configuration can be up to 7 times less than that of a conventional 3D detector, and even a factor of two less than that of a 2D planar detector with a thickness the same as the electrode spacing in the 3D-Trench electrode detector. In the case of non-fully penetrating trench electrodes, the processing is true one-sided with backside being unprocessed. The charge loss due to the dead space associated with the trenches is insignificant as compared to that due to radiation-induced trapping in sLHC environment. Since the large electrode spacing (up to 500 {micro}m) can be realized in the 3D-Trench electrode detector due to their advantage of greatly reduced full depletion voltage, detectors with large pixel cells (therefore small dead volume) can be made for applications in photon science (e.g. X-ray).

  15. Comparison of Martian Surface Radiation Predictions to the Measurements of Mars Science Laboratory Radiation Assessment Detector (MSL/RAD)

    NASA Astrophysics Data System (ADS)

    Kim, M. H. Y.; Cucinotta, F.; Zeitlin, C. J.; Hassler, D.; Ehresmann, B.; Rafkin, S. C.; Wimmer-Schweingruber, R. F.; Böttcher, S. I.; Boehm, E.; Guo, J.; Kohler, J.; Martin-Garcia, C.; Reitz, G.; Posner, A.

    2014-12-01

    For the analysis of radiation risks to astronauts and planning exploratory space missions, detailed knowledge of particle spectra is an important factor. Detailed measurements of the energetic particle radiation environment on the surface of Mars have been made by the Mars Science Laboratory Radiation Assessment Detector (MSL-RAD) on the Curiosity rover since August 2012, and particle fluxes for a wide range of ion species (up to several hundred MeV/u) and high energy neutrons (8 - 1000 MeV) have been available for the first 200 sols. Although the data obtained on the surface of Mars for 200 sols are limited in the narrow energy spectra, the simulation results using the Badhwar-O'Neill galactic cosmic ray (GCR) environment model and the high-charge and energy transport (HZETRN) code are compared to the data. For the nuclear interactions of primary GCR through Mars atmosphere and Curiosity rover, the quantum multiple scattering theory of nuclear fragmentation (QMSFRG) is used, which includes direct knockout, evaporation and nuclear coalescence. Daily atmospheric pressure measurements at Gale Crater by the MSL Rover Environmental Monitoring Station are implemented into transport calculations for describing the daily column depth of atmosphere. Particles impinging on top of the Martian atmosphere reach the RAD after traversing varying depths of atmosphere that depend on the slant angles, and the model accounts for shielding of the RAD by the rest of the instrument. Calculations of stopping particle spectra are in good agreement with the RAD measurements for the first 200 sols by accounting changing heliospheric conditions and atmospheric pressure. Detailed comparisons between model predictions and spectral data of various particle types provide the validation of radiation transport models, and thus increase the accuracy of the predictions of future radiation environments on Mars. These contributions lend support to the understanding of radiation health risks to astronauts for the planning of various mission scenarios.

  16. Comparison of Martian Surface Radiation Predictions to the Measurements of Mars Science Laboratory Radiation Assessment Detector (MSL/RAD)

    NASA Technical Reports Server (NTRS)

    Kim, Myung-Hee Y.; Cucinotta, Francis A.; Zeitlin, Cary; Hassler, Donald M.; Ehresmann, Bent; Rafkin, Scot C. R.; Wimmer-Schweingruber, Robert F; Boettcher, Stephan; Boehm, Eckart; Guo, Jingnan; Koehler, Jan; Martin, Cesar; Reitz, Guenther; Posner, Erik

    2014-01-01

    For the analysis of radiation risks to astronauts and planning exploratory space missions, detailed knowledge of particle spectra is an important factor. Detailed measurements of the energetic particle radiation environment on the surface of Mars have been made by the Mars Science Laboratory Radiation Assessment Detector (MSL-RAD) on the Curiosity rover since August 2012, and particle fluxes for a wide range of ion species (up to several hundred MeV/u) and high energy neutrons (8 - 1000 MeV) have been available for the first 200 sols. Although the data obtained on the surface of Mars for 200 sols are limited in the narrow energy spectra, the simulation results using the Badhwar-O'Neill galactic cosmic ray (GCR) environment model and the high-charge and energy transport (HZETRN) code are compared to the data. For the nuclear interactions of primary GCR through Mars atmosphere and Curiosity rover, the quantum multiple scattering theory of nuclear fragmentation (QMSFRG) is used, which includes direct knockout, evaporation and nuclear coalescence. Daily atmospheric pressure measurements at Gale Crater by the MSL Rover Environmental Monitoring Station are implemented into transport calculations for describing the daily column depth of atmosphere. Particles impinging on top of the Martian atmosphere reach the RAD after traversing varying depths of atmosphere that depend on the slant angles, and the model accounts for shielding of the RAD by the rest of the instrument. Calculations of stopping particle spectra are in good agreement with the RAD measurements for the first 200 sols by accounting changing heliospheric conditions and atmospheric pressure. Detailed comparisons between model predictions and spectral data of various particle types provide the validation of radiation transport models, and thus increase the accuracy of the predictions of future radiation environments on Mars. These contributions lend support to the understanding of radiation health risks to astronauts for the planning of various mission scenarios.

  17. Particle Detectors

    NASA Astrophysics Data System (ADS)

    Grupen, Claus; Shwartz, Boris

    2008-03-01

    Preface to the first edition; Preface to the second edition; Introduction; 1. Interactions of particles and radiation with matter; 2. Characteristic properties of detectors; 3. Units of radiation measurements and radiation sources; 4. Accelerators; 5. Main physical phenomena used for particle detection and basic counter types; 6. Historical track detectors; 7. Track detectors; 8. Calorimetry; 9. Particle identification; 10. Neutrino detectors; 11. Momentum measurement and muon detection; 12. Ageing and radiation effects; 13. Example of a general-purpose detector: Belle; 14. Electronics; 15. Data analysis; 16. Applications of particle detectors outside particle physics; 17. Glossary; 18. Solutions; 19. Resumé; Appendixes; Index.

  18. Particle Detectors

    NASA Astrophysics Data System (ADS)

    Grupen, Claus; Shwartz, Boris

    2011-09-01

    Preface to the first edition; Preface to the second edition; Introduction; 1. Interactions of particles and radiation with matter; 2. Characteristic properties of detectors; 3. Units of radiation measurements and radiation sources; 4. Accelerators; 5. Main physical phenomena used for particle detection and basic counter types; 6. Historical track detectors; 7. Track detectors; 8. Calorimetry; 9. Particle identification; 10. Neutrino detectors; 11. Momentum measurement and muon detection; 12. Ageing and radiation effects; 13. Example of a general-purpose detector: Belle; 14. Electronics; 15. Data analysis; 16. Applications of particle detectors outside particle physics; 17. Glossary; 18. Solutions; 19. Resumé; Appendixes; Index.

  19. Fabrication and performance of p-i-n CdTe radiation detectors

    NASA Astrophysics Data System (ADS)

    Niraula, Madan; Mochizuki, Daisuke; Aoki, Toru; Tomita, Yasuhiro; Nihashi, Tokuaki; Hatanaka, Yoshinori

    1999-10-01

    We report on the fabrication and performance of CdTe radiation detectors in a new p-i-n structure which helps to reduce the leakage current to a minimum level. Chlorine-doped single-crystal CdTe substrates having resistivity in the order of 10 9 ? cm were used in this study. Iodine-doped n-type CdTe layers were grown homoepitaxially on one face of each crystals using the hydrogen plasma-radical-assisted metalorganic chemical vapor deposition technique at low substrate temperature of 150°C. Indium electrode was evaporated on the n-CdTe side while a gold electrode on the opposite side acted as a p-type contact. Detectors thus fabricated exhibited low leakage current (below 0.4 nA/mm 2 at 250 V applied reverse bias for the best one) and good performance at room temperature. Spectral response of the detectors showed improved energy resolution for Am-241, Co-57, and Cs-137 radioisotopes. Detectors were further tested with X-ray photons of different intensities for their potential application in imaging systems and promising responses were obtained.

  20. Artificial diamonds as radiation-hard detectors for ultra-fast fission-fragment timing

    NASA Astrophysics Data System (ADS)

    Oberstedt, S.; Borcea, R.; Bry?, T.; Gamboni, Th.; Geerts, W.; Hambsch, F.-J.; Oberstedt, A.; Vidali, M.

    2013-06-01

    In the framework of the construction of the double time-of-flight spectrometer VERDI, where we aim at measuring pre- and post-neutron masses directly and simultaneously, ultra-fast time pick-up detectors based on artificial diamond material were investigated for the first time with fission fragments from 252Cf (0.5 MeV/uradiation fluence was determined up to at least 109 fission-fragments/cm2 together with more than 3.5×109 neutrons/cm2 and 3×1010?-particles/cm2. This fluence is characteristic for fission experiments. The pre-requisite for the observed signal stability is the application of priming of the diamond material with a strong ?-source for about 48 h. The intrinsic timing resolution of a 100 ?m thick polycrystalline CVD diamond detector with a size of 1×1 cm2 was determined to ?int=(283±41) ps by comparison with Monte-Carlo simulations. Using broadband pre-amplifiers, 4-fold segmented detectors of same total size and with a thickness of 180 ?m show an intrinsic timing resolution of ?int=(106±21) ps. This is highly competitive with the best micro-channel plate detectors. Due to the limited and batch-dependent charge collection efficiency of poly-crystalline diamond material, the detection efficiency for fission fragments may be smaller than 100%.

  1. Analysis of laser-generated plasma ionizing radiation by synthetic single crystal diamond detectors

    NASA Astrophysics Data System (ADS)

    Marinelli, M.; Milani, E.; Prestopino, G.; Verona, C.; Verona-Rinati, G.; Cutroneo, M.; Torrisi, L.; Margarone, D.; Velyhan, A.; Krasa, J.; Krousky, E.

    2013-05-01

    Diamond based detectors have been used in order to analyze the ionizing radiation emitted from the laser-generated plasma. High energy proton/ion beams were generated at Prague Asterix Laser System (PALS) Centre by the sub-nanosecond kJ-class laser at intensities above 1016 W/cm2. The tested detectors consisted of a photoconductive device based on high quality chemical vapor deposition (CVD) single crystal diamond, produced at Rome "Tor Vergata" University. They have been operated in planar configuration, having inter-digitized electrodes. The proposed diamond detectors were able to measure UV, X-rays, electrons and ions. They have been employed in time-of-flight (TOF) configuration and their reliability was checked by comparison with standard ion collectors (mostly used at PALS). Both the forward and backward expanding plasma was characterized in the experiment. The results indicate that diamond detectors are very promising for the characterization of fast proton and ion beams produced by high power laser systems.

  2. Detector control system for the ATLAS Transition Radiation Tracker: architecture and development techniques

    NASA Astrophysics Data System (ADS)

    Bana?, El?bieta; Hajduk, Zbigniew; Olszowska, Jolanta

    2012-05-01

    The ATLAS Transition Radiation Tracker (TRT) is the outermost of the three sub-systems of the ATLAS Inner Detector at the Large Hadron Collider at CERN. With ~300000 drift tube proportional counters (straws) filled with stable gas mixture and high voltage biased it provides precise quasi-continuous tracking and particles identification. Safe, coherent and efficient operation of the TRT is fulfilled with the help of the Detector Control System (DCS) running on 11 computers as PVSS (industrial SCADA) projects. Standard industrial and custom developed server applications and protocols are used for reading hardware parameters. Higher level control system layers based on the CERN JCOP framework allow for automatic control procedures, efficient error recognition and handling and provide a synchronization mechanism with the ATLAS data acquisition system. Different data bases are used to store the detector online parameters, the configuration parameters and replicate a subset of them used to flag data quality for physics reconstruction. The TRT DCS is fully integrated with the ATLAS Detector Control System.

  3. A search for a heavy Majorana neutrino and a radiation damage simulation for the HF detector

    NASA Astrophysics Data System (ADS)

    Wetzel, James William

    A search for heavy Majorana neutrinos is performed using an event signature defined by two same-sign muons accompanied by two jets. This search is an extension of previous searches, (L3, DELPHI, CMS, ATLAS), using 19.7 fb -1 of data from the 2012 Large Hadron Collider experimental run collected by the Compact Muon Solenoid experiment. A mass window of 40-500 GeV/ c2 is explored. No excess events above Standard Model backgrounds is observed, and limits are set on the mixing element squared, |VmuN|2, as a function of Majorana neutFnrino mass. The Hadronic Forward (HF) Detector's performance will degrade as a function of the number of particles delivered to the detector over time, a quantity referred to as integrated luminosity and measured in inverse femtobarns (fb-1). In order to better plan detector upgrades, the CMS Forward Calorimetry Task Force (FCAL) group and the CMS Hadronic Calorimeter (HCAL) group have requested that radiation damage be simulated and the subsequent performance of the HF subdetector be studied. The simulation was implemented into both the CMS FastSim and CMS FullSim simulation packages. Standard calorimetry performance metrics were computed and are reported. The HF detector can expect to perform well through the planned delivery of 3000 fb-1.

  4. Next Generation Semiconductor-Based Radiation Detectors Using Cadmium Magnesium Telluride

    SciTech Connect

    Trivedi, Sudhir B; Kutcher, Susan W; Palsoz, Witold; Berding, Martha; Burger, Arnold

    2014-11-17

    The primary objective of Phase I was to perform extensive studies on the purification, crystal growth and annealing procedures of CdMgTe to gain a clear understanding of the basic material properties to enable production of detector material with performance comparable to that of CdZnTe. Brimrose utilized prior experience in the growth and processing of II-VI crystals and produced high purity material and good quality single crystals of CdMgTe. Processing techniques for these crystals including annealing, mechanical and chemical polishing, surface passivation and electrode fabrication were developed. Techniques to characterize pertinent electronic characteristics were developed and gamma ray detectors were fabricated. Feasibility of the development of comprehensive defect modeling in this new class of material was demonstrated by our partner research institute SRI International, to compliment the experimental work. We successfully produced a CdMgTe detector that showed 662 keV gamma response with energy resolution of 3.4% (FWHM) at room temperature, without any additional signal correction. These results are comparable to existing CdZnTe (CZT) technology using the same detector size and testing conditions. We have successfully demonstrated detection of gamma-radiation from various isotopes/sources, using CdMgTe thus clearly proving the feasibility that CdMgTe is an excellent, low-cost alternative to CdZnTe.

  5. Measurements of High Energy X-Ray Dose Distributions Using Multi-Dimensional Fiber-Optic Radiation Detectors

    NASA Astrophysics Data System (ADS)

    Jang, Kyoung Won; Cho, Dong Hyun; Shin, Sang Hun; Lee, Bongsoo; Chung, Soon-Cheol; Tack, Gye-Rae; Yi, Jeong Han; Kim, Sin; Cho, Hyosung

    In this study, we have fabricated multi-dimensional fiber-optic radiation detectors with organic scintillators, plastic optical fibers and photo-detectors such as photodiode array and a charge-coupled device. To measure the X-ray dose distributions of the clinical linear accelerator in the tissue-equivalent medium, we have fabricated polymethylmethacrylate phantoms which have one-dimensional and two-dimensional fiber-optic detector arrays inside. The one-dimensional and two-dimensional detector arrays can be used to measure percent depth doses and surface dose distributions of high energy X-ray in the phantom respectively.

  6. A concept for laboratory studies of radiation detectors over a broad dynamic-range: instabilities evaluation in THGEM-structures

    NASA Astrophysics Data System (ADS)

    Bressler, S.; Moleri, L.; Arazi, L.; Erdal, E.; Rubin, A.; Pitt, M.; Breskin, A.

    2014-03-01

    A simple methodology for evaluating the dynamic-range of gas avalanche detectors in the laboratory is presented and discussed. It comprises two tools: a charge injector of tunable gain which transfers radiation-induced amplified electron swarms to the investigated detector to mimic events with well defined primary-ionization spectra, and a systematic approach for measuring the detector's discharge probability. The methodology, applicable to a broad range of detectors, is applied here for instability studies in various single-stage THGEM and THGEM-WELL structures. The results indicate upon a somewhat larger attainable dynamic range in a single-stage THGEM operated with additional multiplication in the induction gap.

  7. Traceable calibration of a fibre-coupled superconducting nano-wire single photon detector using characterized synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Müller, Ingmar; Klein, Roman M.; Werner, Lutz

    2014-12-01

    Radiometric calibrations of fibre-coupled single photon detectors are experiencing growing demand, especially at the telecommunication wavelengths. In this paper, the radiometric calibration of a fibre-coupled superconducting nano-wire single photon detector at the telecom wavelength 1.55 µm by means of well-characterized synchrotron radiation is described. This substitution method is based on the unique properties of synchrotron radiation and the Metrology Light Source, the dedicated electron storage ring of the Physikalisch-Technische Bundesanstalt, and is suitable for fibre-coupled single photon detectors. The Metrology Light Source is used as a light source with a high dynamic range of the radiant power to bridge the radiometric gap occurring in the transition from radiant power measurements and the counting of photons with single photon detectors. Very low uncertainties below 2% have been achieved in the measurement of the detection efficiency of a fibre-coupled superconducting nano-wire single photon detector.

  8. Bidimensional polycrystalline CVD diamond detector for Intensity Modulated Radiation Therapy pre-treatment verifications

    NASA Astrophysics Data System (ADS)

    Zani, M.; Scaringella, M.; Talamonti, C.; De Sio, A.; Pace, E.; Tozzetti, L.; Baldi, A.; Bucciolini, M.; Bruzzi, M.

    2015-03-01

    This study aims at investigating the possible employment for pre-treatment verifications in Intensity Modulated Radiation Therapy (IMRT) of a polycrystalline Chemical Vapour Deposited (pCVD) diamond bidimensional detector. The pCVD device, with an area of 2.5 × 2.5 cm2 (12 × 12 pixels), has been used to measure dose maps of a 10 MVRX prostatic IMRT field. Its response was compared both with a commercial bi-dimensional detector made with silicon and with Treatment Planning System (TPS) calculations.Measurement provided promising results on a map of 1.8 × 12.6 cm2. Absorbed doses measured along IMRT profiles by our device are consistent with the ones acquired with the commercial device and an overall good agreement with respect to the TPS was found for the diamond dosimeter.

  9. A Compact Combinatorial Device for Measurement of Nonlinearity of Radiation Detectors

    NASA Astrophysics Data System (ADS)

    Saunders, P.; White, D. R.; Edgar, H.

    2015-03-01

    A new compact computer-controlled device using a combinatorial technique for measuring the nonlinearity of radiation detectors is described. The device consists of two sets of four beam-splitter cubes optically cemented together and arranged so that radiation from a single source is split into four separate paths, then recombined after passing through one of five neutral density filters placed in each path. This allows for the measurement of 625 approximately equi-spaced inter-related flux levels based on only 16 unknown transmittance values. These can be solved for by least-squares fitting, leaving 609 degrees of freedom remaining to determine the nonlinearity of the detector. A novel aspect of the design is the use of neutral density glass plates optically cemented along all the external faces of the beam-splitter cubes, which act as beam dumps for any reflected or scattered radiation. The cube faces in the desired beam paths have clear glass plates with an anti-reflection coating applied at the wavelength of interest optically cemented to them. Operation at other wavelengths is achieved by simply replacing these plates with plates coated for the new wavelength. The performance of the device has been tested using a silicon photodiode with a collimated 650 nm LED as the source. The results demonstrate that the device is able to measure linearity to better than 1 part in.

  10. Response of a hybrid pixel detector (MEDIPIX3) to different radiation sources for medical applications

    NASA Astrophysics Data System (ADS)

    Chumacero, E. Miguel; De Celis Alonso, B.; Martínez Hernández, M. I.; Vargas, G.; Moreno Barbosa, F.; Moreno Barbosa, E.

    2014-11-01

    The development in semiconductor CMOS technology has enabled the creation of sensitive detectors for a wide range of ionizing radiation. These devices are suitable for photon counting and can be used in imaging and tomography X-ray diagnostics. The Medipix[1] radiation detection system is a hybrid silicon pixel chip developed for particle tracking applications in High Energy Physics. Its exceptional features (high spatial and energy resolution, embedded ultra fast readout, different operation modes, etc.) make the Medipix an attractive device for applications in medical imaging. In this work the energy characterization of a third-generation Medipix chip (Medipix3) coupled to a silicon sensor is presented. We used different radiation sources (strontium 90, iron 55 and americium 241) to obtain the response curve of the hybrid detector as a function of energy. We also studied the contrast of the Medipix as a measure of pixel noise. Finally we studied the response to fluorescence X rays from different target materials (In, Pd and Cd) for the two data acquisition modes of the chip; single pixel mode and charge summing mode.

  11. Response of a hybrid pixel detector (MEDIPIX3) to different radiation sources for medical applications

    SciTech Connect

    Chumacero, E. Miguel; De Celis Alonso, B.; Martínez Hernández, M. I.; Vargas, G.; Moreno Barbosa, E.; Moreno Barbosa, F.

    2014-11-07

    The development in semiconductor CMOS technology has enabled the creation of sensitive detectors for a wide range of ionizing radiation. These devices are suitable for photon counting and can be used in imaging and tomography X-ray diagnostics. The Medipix[1] radiation detection system is a hybrid silicon pixel chip developed for particle tracking applications in High Energy Physics. Its exceptional features (high spatial and energy resolution, embedded ultra fast readout, different operation modes, etc.) make the Medipix an attractive device for applications in medical imaging. In this work the energy characterization of a third-generation Medipix chip (Medipix3) coupled to a silicon sensor is presented. We used different radiation sources (strontium 90, iron 55 and americium 241) to obtain the response curve of the hybrid detector as a function of energy. We also studied the contrast of the Medipix as a measure of pixel noise. Finally we studied the response to fluorescence X rays from different target materials (In, Pd and Cd) for the two data acquisition modes of the chip; single pixel mode and charge summing mode.

  12. Development of a cryogenic radiation detector for mapping radio frequency superconducting cavity field emissions

    SciTech Connect

    Danny Dotson; John Mammosser

    2005-05-01

    Field emissions in a super conducting helium cooled RF cavity and the production of radiation (mostly X-Rays) have been measured externally on cryomodules at Jefferson Lab since 1991. External measurements are limited to radiation energies above 100 keV due to shielding of the stainless steel cryogenic body. To measure the onset of and to map field emissions from a superconducting cavity requires the detecting instrument be inside the shield and within the liquid Helium. Two possible measurement systems are undergoing testing at JLab. A CsI detector array set on photodiodes and an X-Ray film camera with a fixed aperture. Several devices were tested in the cell with liquid Helium without success. The lone survivor, a CsI array, worked but saturated at high power levels due to backscatter. The array was encased in a lead shield with a slit opening set to measure the radiation emitted directly from the cell eliminating a large portion of the backscatter. This is a work in progress and te sting should be complete before the PAC 05. The second system being tested is passive. It is a shielded box with an aperture to expose radiation diagnostic film located inside to direct radiation from the cell. Developing a technique for mapping field emissions in cryogenic cells will assist scientists and engineers in pinpointing any surface imperfections for examination.

  13. Photodiode radiation hardness, lyman-alpha emitting galaxies and photon detection in liquid argon neutrino detectors

    NASA Astrophysics Data System (ADS)

    Baptista, Brian

    My dissertation is comprised of three projects: 1) studies of Lyman-alpha Emitting galaxies (LAEs), 2) radiation hardness studies of InGaAs photodiodes (PDs), and 3) scintillation photon detection in liquid argon (LAr) neutrino detectors. I began work on the project that has now become WFIRST, developing a science case that would use WFIRST after launch for the observation of LAEs. The radiation hardness of PDs was as an effort to support the WFIRST calibration team. When WFIRST was significantly delayed, I joined an R&D effort that applied my skills to work on photon detection in LAr neutrino detectors. I report results on a broadband selection method developed to detect high equivalent width (EW) LAEs. Using photometry from the CFHT-Legacy Survey Deep 2 and 3 fields, I have spectroscopically confirmed 63 z=2.5-3.5 LAEs using the WIYN/Hydra spectrograph. Using UV continuum-fitting techniques I computed properties such as EWs, internal reddening and star formation rates. 62 of my LAEs show evidence to be normal dust-free LAEs. Second, I present an investigation into the effects of ionizing proton radiation on commercial off-the-shelf InGaAs PDs. I developed a monochromator-based test apparatus that utilized NIST-calibrated reference PDs. I tested the PDs for changes to their dark current, relative responsivity as a function of wavelength, and absolute responsivity. I irradiated the test PDs using 30, 52, and 98 MeV protons at the IU Cyclotron Facility. I found the InGaAs PDs showed increased dark current as the fluence increased with no evidence of broadband response degradation at the fluences expected at an L2 orbit and a 10-year mission lifetime. Finally, I detail my efforts on technology development of both optical detector technologies and waveshifting light guide construction for LAr vacuum UV scintillation light. Cryogenic neutrino detectors use photon detection for both accelerator based science and for SNe neutrino detection and proton decay. I have developed waveshifter doped cast acrylic light guides that convert scintillation light and guide the waveshifted light to SiPMs detectors.

  14. Re-evaluating Galileo Energetic Particle Detector data based on radiation detector decay; for use in estimating Sputtering Erosion rates on Europa.

    NASA Astrophysics Data System (ADS)

    Lee-Payne, Z.; Grande, M.; Krupp, N.; Paranicas, C.; Roussos, E.; Kollmann, P.

    2015-10-01

    The Energetic Particle Detector (EPD) launched in 1989 on the Galileo satellite took data on the Jovian Particle environment for 6 years before its demise [1]. Over the course of the mission the detectors in the Composition Measurement System (CMS) have visibly decayed with higher mass particles, specifically Oxygen and Sulphur, reading far lower energies at later epochs. By considering the non-steady accumulation of damage in the detector, as well as the operation of the priority channel data recording system in place on the EPD, an evolving correction can be made. Adjusting the data to account for the damage to the detectors will improve our understanding of the Jovian radiation environment. In particular, we can use the revised fluxes to re-evaluate the effect of the particle environment on the surfaces of the icy moons.

  15. High spatial resolution radiation detectors based on hydrogenated amorphous silicon and scintillator

    SciTech Connect

    Jing, T

    1995-05-01

    Hydrogenated amorphous silicon (a-Si:H) as a large-area thin film semiconductor with ease of doping and low-cost fabrication capability has given a new impetus to the field of imaging sensors; its high radiation resistance also makes it a good material for radiation detectors. In addition, large-area microelectronics based on a-Si:H or polysilicon can be made with full integration of peripheral circuits, including readout switches and shift registers on the same substrate. Thin a-Si:H p-i-n photodiodes coupled to suitable scintillators are shown to be suitable for detecting charged particles, electrons, and X-rays. The response speed of CsI/a-Si:H diode combinations to individual particulate radiation is limited by the scintillation light decay since the charge collection time of the diode is very short (< 10ns). The reverse current of the detector is analyzed in term of contact injection, thermal generation, field enhanced emission (Poole-Frenkel effect), and edge leakage. A good collection efficiency for a diode is obtained by optimizing the p layer of the diode thickness and composition. The CsI(Tl) scintillator coupled to an a-Si:H photodiode detector shows a capability for detecting minimum ionizing particles with S/N {approximately}20. In such an arrangement a p-i-n diode is operated in a photovoltaic mode (reverse bias). In addition, a p-i-n diode can also work as a photoconductor under forward bias and produces a gain yield of 3--8 for shaping times of 1 {micro}s. The mechanism of the formation of structured CsI scintillator layers is analyzed. Initial nucleation in the deposited layer is sensitive to the type of substrate medium, with imperfections generally catalyzing nucleation. Therefore, the microgeometry of a patterned substrate has a significant effect on the structure of the CsI growth.

  16. Wide Band-Gap Semiconductor Radiation Detectors: Science Fiction, Horror Story, or Headlines (460th Brookhaven Lecture)

    SciTech Connect

    James, Ralph

    2010-08-18

    With radiation constantly occurring from natural sources all around us -- from food, building materials, and rays from the sun, to name a few -- detecting radiotracers for medical procedures and other radiation to keep people safe is not easy. In order to make better use of radiation to diagnose or treat certain health conditions, or to track radiological materials being transported, stored, and used, the quest is on to develop improved radiation detectors. James gives a brief introduction on radiation detection and explain how it is used in applications ranging from medical to homeland security. He then discusses how new materials and better ways to analyze them here at the National Synchrotron Light Source (NSLS) and the future NSLS-II will lead to a new class of radiation detectors that will provide unprecedented advances in medical and industrial imaging, basic science, and the nonproliferation of nuclear materials.

  17. Method and device for demounting in a radiation detector a photomultiplier tube

    SciTech Connect

    Persyk, D.E.; Stoub, E.W.

    1986-03-11

    A device is described for demounting in a radiation detector a photomultiplier tube which is bonded with its scintillation crystal assembly by means of an elastic light transparent adhesive, comprising: (a) a music wire of about 0.01 to 0.03 inch diameter which forms a noose between its wire ends, the noose being provided for being placed aroung the bond; and (b) twisting means connected with both wire ends for twisting them such that the noose becomes smaller thereby sharing the bond.

  18. 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.

  19. A Versatile Hemispherical Great Area X-ray Detector for Synchrotron Radiation

    SciTech Connect

    Figueroa, Rodolfo; Belmar, Felipe

    2009-01-29

    This work presents an X-ray detector with fullerene C60 semi spherical geometry constituted by a set of small cylindrical proportional counter units with needles anodes, which are located in the surface of an hemispherical plastic support. The sample to be analyzed is placed on the center of the hemisphere base. The radiation may enter by one of its flanks or through the hemisphere top. The hemispherical zone that exists between the holder sample base and the proportional counters can be vacuumed, aired or filled with counter gas.

  20. Research progress in radiation detectors, pattern recognition programs, and radiation damage determination in DNA

    NASA Technical Reports Server (NTRS)

    Baily, N. A.

    1973-01-01

    The radiological implications of statistical variations in energy deposition by ionizing radiation were investigated in the conduct of the following experiments: (1) study of the production of secondary particles generated by the passage of the primary radiation through bone and muscle; (2) the study of the ratio of nonreparable to reparable damage in DNA as a function of different energy deposition patterns generated by X rays versus heavy fast charged particles; (3) the use of electronic radiography systems for direct fluoroscopic tomography and for the synthesis of multiple planes and; (4) the determination of the characteristics of systems response to split fields having different contrast levels, and of minimum detectable contrast levels between the halves under realistic clinical situations.

  1. Characterisation of radiation field for irradiation of biological samples at nuclear reactor-comparison of twin detector and recombination methods.

    PubMed

    Golnik, N; Gryzi?ski, M A; Kowalska, M; Meronka, K; Tulik, P

    2014-10-01

    Central Laboratory for Radiological Protection is involved in achieving scientific project on biological dosimetry. The project includes irradiation of blood samples in radiation fields of nuclear reactor. A simple facility for irradiation of biological samples has been prepared at horizontal channel of the nuclear reactor MARIA in NCBJ in Poland. The radiation field, composed mainly of gamma radiation and thermal neutrons, has been characterised in terms of tissue kerma using twin-detector technique and recombination chambers. PMID:24366246

  2. Gadolinium-doped water cerenkov-based neutron and high energy gamma-ray detector and radiation portal monitoring system

    DOEpatents

    Dazeley, Steven A; Svoboda, Robert C; Bernstein, Adam; Bowden, Nathaniel

    2013-02-12

    A water Cerenkov-based neutron and high energy gamma ray detector and radiation portal monitoring system using water doped with a Gadolinium (Gd)-based compound as the Cerenkov radiator. An optically opaque enclosure is provided surrounding a detection chamber filled with the Cerenkov radiator, and photomultipliers are optically connected to the detect Cerenkov radiation generated by the Cerenkov radiator from incident high energy gamma rays or gamma rays induced by neutron capture on the Gd of incident neutrons from a fission source. The PMT signals are then used to determine time correlations indicative of neutron multiplicity events characteristic of a fission source.

  3. Radiation detector using a bulk high T.sub.c superconductor

    DOEpatents

    Artuso, Joseph F. (Santa Barbara, CA); Franks, Larry A. (Santa Barbara, CA); Hull, Kenneth L. (Ventura, CA); Symko, Orest G. (Salt Lake City, UT)

    1993-01-01

    A radiation detector (10) is provided, wherein a bulk high T.sub.c superconducting sample (11) is placed in a magnetic field and maintained at a superconducting temperature. Photons of incident radiation will cause localized heating in superconducting loops of the sample destroying trapped flux and redistributing the fluxons, and reducing the critical current of the loops. Subsequent cooling of the sample in the magnetic field will cause trapped flux redistributed Abrikosov fluxons and trapped Josephson fluxons. The destruction and trapping of the fluxons causes changes in the magnetization of the sample inducing currents in opposite directions in a pickup coil (12) which is coupled by an input coil (15) to an rf SQUID (16).

  4. Photoemission analysis of chemically modified TlBr surfaces for improved radiation detectors

    NASA Astrophysics Data System (ADS)

    Nelson, A. J.; Lee, J.-S.; Stanford, J. A.; Grant, W. K.; Voss, L. F.; Beck, P. R.; Graff, R. T.; Swanberg, E. L.; Conway, A. M.; Nikolic, R. J.; Payne, S. A.; Kim, H.; Cirignano, L. J.; Shah, K.

    2013-09-01

    Device-grade TlBr was subjected to various chemical treatments used in room temperature radiation detector fabrication to determine the resulting surface composition and electronic structure. Samples of as polished TlBr were treated separately with 2%Br:MeOH, 10%HF, 10%HCl and 96%SOCl2 solutions. High-resolution photoemission measurements on the valence band electronic structure and Tl 4f, Br 3d, Cl 2p and S 2p core lines were used to evaluate surface chemistry. Results suggest anion substitution at the surface with subsequent shallow heterojunction formation. Surface chemistry and valence band electronic structure were further correlated with the goal of optimizing the long-term stability and radiation response.

  5. Measurements of Coherent Cerenkov Radiation in Rock Salt: Implications for GZK Neutrino Underground Detector

    SciTech Connect

    Milincic, R.

    2005-04-15

    We present results of the study of coherent Cerenkov radiation from negative charge excess in electromagnetic cascades (Askaryan effect) in synthetic rock salt. In the .rst part of this work, the accelerator measurement was performed in the Stanford Linear Accelerator with pulsed bunches of 28.5 GeV electrons passing through Aluminum radiators, which produced a beam of bremsstrahlung photons in direction of the salt. Measurements cover the range of shower energies from 2.7 x 10{sup 14}eV up to 8.0 x 10{sup 18}eV . With three different types of radio frequency receivers which altogether span the range of 200-20000 MHz, we analyzed coherency of radiation produced within the target salt. In the second part, we conducted a search for the coherent radio pulses induced by high energy cosmic-rays. As a medium for detection of Cerenkov radiation, we use a 22 ton target of synthetic rock salt contained within a scintillation counter cosmic-ray hodoscope. Two parallel arrays of crossed bowtie antennas are put inside the salt bed and used as a detection tool. Here, we present expected rate for detection of cosmic ray protons and secondary muons above ''Salt Factory'' sensitivity of 1.8 TeV. These measurements provide an excellent baseline for the Monte Carlo simulation of the performance of the 15.6 km{sup 3} GZK neutrino detector placed inside a salt-dome formation. Results of the simulations show that this kind of detector can be used to put constraints on all GZK neutrino models in one year of work.

  6. Hydrogenated amorphous silicon radiation detectors: Material parameters, radiation hardness, charge collection

    SciTech Connect

    Qureshi, S.

    1991-01-01

    For nearly two decades now hydrogenated amorphous silicon has generated considerable interest for its potential use in various device applications namely, solar cells, electrolithography, large-area electronics etc. The development of efficient and economic solar cells has been on the forefront of this research. This interest in hydrogenated amorphous silicon has been motivated by the fact that amorphous silicon can be deposited over a large area at relatively low cost compared to crystalline silicon. Hydrogenated amorphous silicon, frequently abbreviated as a-Si:H, used in solar-cell applications is a micron or less thick. The basic device structure is a p-i-n diode where the i layer is the active layer for radiation to interact. This is so because intrinsic a-Si:H has superior electrical properties in comparison to doped a-Si:H which serves the purpose of forming a potential barrier on either end of the i layer. The research presented in this dissertation was undertaken to study the properties of a-Si:H for radiation detection applications in physics and medicine.

  7. Sub-nanosecond time resolution detector based on APD for Synchrotron Radiation ultrafast experiments

    E-print Network

    Li, Zhen-jie; Liu, Peng; Wang, Shan-feng; Dong, Wei-wei; Zhou, Yang-fan

    2015-01-01

    Synchrotron radiation light sources produce intense beam of X-ray with ultra-short pulse and nanosecond period. This of-fers the opportunities for the time resolution experiments. Achieving higher counting rate and faster arriving time is diffi-cult for common detectors. But avalanche photodiodes (APD) based on silicon which have been commercially available1 with large active areas (e.g.10mmx10mm@ Perkin-Elmer Inc.) could satisfy the demands due to their good time resolution, low noise and large area.We investigate the high counting rate and nanosecond time resolution detector with APD. The detector's fast amplifier was designed with the gain of about 60dB (1000). The amplifier included with three stages RF-preamplifier using MAR6+ chip5 for the carefully controlling the circuit oscillation. Some measures have been taken for the preamplifiers good performance such as using resistance net between RF-preamplifier chip and the isolation of high voltage circuit from the preamplifier. The time resolution of the pr...

  8. Material analysis of the CZT crystal grown for a radiation detector

    NASA Astrophysics Data System (ADS)

    Kim, Han Soo; Jeong, Manhee; Kim, Young Soo; Kim, Dong Jin; Choi, Hyo Jeong

    2015-01-01

    Room-temperature semiconductor radiation detectors, such as CdZnTe (CZT) and CdTe detectors, are being developed and grown worldwide owing to their high performances as a gamma-ray detector. A 2? CZT ingot was grown using a 6-zone low-pressure (LP) Bridgman furnace at the Korea Atomic Energy Research Institute (KAERI). To increase the resistivity, indium (In) was doped at 5 ppm and 7 ppm, respectively. Material analysis results obtained by using inductively coupled plasma mass spectrometry (ICP-MS), X-ray diffractometry (XRD), and an infrared (IR) scope system were compared with the I-V results with respect to the location on the grown ingots and doping concentration. A (1,1,1) orientation and 1.41 × 1011 ?·cm resistivity were measured in the middle part of the ingot. In addition, Te inclusions were also homogeneously shown. The variation in the I-V characteristics with respect to the preparation conditions of the crystals was also addressed.

  9. Characterization of bismuth tri-iodide single crystals for wide band-gap semiconductor radiation detectors

    NASA Astrophysics Data System (ADS)

    Lintereur, Azaree T.; Qiu, Wei; Nino, Juan C.; Baciak, James

    2011-10-01

    Bismuth tri-iodide is a wide band-gap semiconductor material that may be able to operate as a radiation detector without any cooling mechanism. This material has a higher effective atomic number than germanium and CdZnTe, and thus should have a higher gamma-ray detection efficiency, particularly for moderate and high energy gamma-rays. Unfortunately, not much is known about bismuth tri-iodide, and the general properties of the material need to be investigated. Bismuth tri-iodide does not suffer from some of the material issues, such as a solid state phase transition and dissociation in air, that mercuric iodide (another high-Z, wide band-gap semiconductor) does. Thus, bismuth tri-iodide is both easier to grow and handle than mercuric iodide. A modified vertical Bridgman growth technique is being used to grow large, single bismuth tri-iodide crystals. Zone refining is being performed to purify the starting material and increase the resistivity of the crystals. The single crystals being grown are typically several hundred mm 3. The larger crystals grown are approximately 2 cm 3. Initial detectors are being fabricated using both gold and palladium electrodes and palladium wire. The electron mobility measured using an alpha source was determined to be 260±50 cm 2/Vs. An alpha spectrum was recorded with one of the devices; however the detector appears to suffer from polarization.

  10. Monte Carlo simulation for the electron cascade due to gamma rays in semiconductor radiation detectors

    SciTech Connect

    Narayan, Raman D.; Miranda, Ryan; Rez, Peter

    2012-03-15

    A Monte Carlo code was developed for simulating the electron cascade in radiation detector materials. The electron differential scattering cross sections were derived from measured electron energy-loss and optical spectra, making the method applicable for a wide range of materials. The detector resolution in a simplified model system shows dependence on the bandgap, the plasmon strength and energy, and the valence band width. In principle, these parameters could be optimized to improve detector performance. The intrinsic energy resolution was calculated for three semiconductors: silicon (Si), gallium arsenide (GaAs), and zinc telluride (ZnTe). Setting the ionization thresholds for electrons and holes is identified as a critical issue, as this strongly affects both the average electron-hole pair energy w and the Fano factor F. Using an ionization threshold from impact ionization calculations as an effective bandgap yields pair energies that are well matched to measured values. Fano factors of 0.091 (Si), 0.100 (GaAs), and 0.075 (ZnTe) were calculated. The Fano factor calculated for silicon using this model was lower than some results from past simulations and experiments. This difference could be attributed to problems in simulating inter-band transitions and the scattering of low-energy electrons.

  11. Performance of the Time Expansion Chamber / Transition Radiation Detector in PHENIX Experiment at RHIC

    NASA Astrophysics Data System (ADS)

    Luiz Silva, Cesar

    2004-10-01

    The Time Expansion Chamber / Transition Radiation Detector (TEC/TRD) in the PHENIX Experiment at RHIC measures ionization losses (dE/dX) and transition radiation from charged particles produced by beam collisions. It is designed to perform tracking and identification for charged particles on very high particle multiplicity environment. The TEC/TRD consists of 24 wire chambers readout on both sides filled with recycled Xe-based gas mixture. This wire chamber configuration, besides providing measurements of ionization losses for charged particles, can absorb X-Ray photons generated by transition radiation from incident particles with ?>1000 crossing fiber radiators placed at the entrance of the chambers. This allows TEC/TRD to distinguish electrons from the huge pion signal produced over a broad momentum range (1GeV/c

  12. Radiation tolerance of prototype BTeV pixel detector readout chips

    SciTech Connect

    Gabriele Chiodini et al.

    2002-07-12

    High energy and nuclear physics experiments need tracking devices with increasing spatial precision and readout speed in the face of ever-higher track densities and increased radiation environments. The new generation of hybrid pixel detectors (arrays of silicon diodes bump bonded to arrays of front-end electronic cells) is the state of the art technology able to meet these challenges. We report on irradiation studies performed on BTeV pixel readout chip prototypes exposed to a 200 MeV proton beam at Indiana University Cyclotron Facility. Prototype pixel readout chip preFPIX2 has been developed at Fermilab for collider experiments and implemented in standard 0.25 micron CMOS technology following radiation tolerant design rules. The tests confirmed the radiation tolerance of the chip design to proton total dose up to 87 MRad. In addition, non destructive radiation-induced single event upsets have been observed in on-chip static registers and the single bit upset cross section has been extensively measured.

  13. Properties of native defects in InI for potential radiation detector application

    SciTech Connect

    Biswas, Koushik; Du, Mao-Hua

    2011-01-01

    Heavy-metal halide semiconductors have attracted much interest recently for their potential applications in radiation detection because the large atomic numbers (high Z) of their constituent elements enable efficient radiation absorption and their large band gaps allow room temperature operation. However, defect properties of these halides and their connection to carrier transport are little known. In this paper, we present first-principles calculations on native defects in InI, which is a promising material for applications in room temperature radiation detection. The important findings are: (1) anion and cation vacancies (Schottky defects) form the dominant low-energy defects that can pin the Fermi level close to midgap, leading to high resistivity that is required for a good radiation detector material; (2) the anion vacancy in InI induces a deep electron trap, which should reduce electron mobility-lifetime product in InI; (3) low diffusion barriers of vacancies could be responsible for the observed polarization phenomenon at room temperature

  14. Development of radiation detectors based on hydrogenated amorphous silicon and its alloys

    SciTech Connect

    Hong, Wan-Shick

    1995-04-01

    Hydrogenated amorphous silicon and related materials have been applied to radiation detectors, utilizing their good radiation resistance and the feasibility of making deposits over a large area at low cost. Effects of deposition parameters on various material properties of a-Si:H have been studied to produce a material satisfying the requirements for specific detection application. Thick(-{approximately}50 {mu}m), device quality a-Si:H p-i-n diodes for direct detection of minimum ionizing particles have been prepared with low internal stress by a combination of low temperature growth, He-dilution of silane, and post annealing. The structure of the new film contained voids and tiny crystalline inclusions and was different from the one observed in conventional a-Si:H. Deposition on patterned substrates was attempted as an alternative to controlling deposition parameters to minimize substrate bending and delamination of thick a-Si:H films. Growth on an inversed-pyramid pattern reduced the substrate bending by a factor of 3{approximately}4 for the same thickness film. Thin (0.1 {approximately} 0.2 {mu}m) films of a-Si:H and a-SiC:H have been applied to microstrip gas chambers to control gain instabilities due to charges on the substrate. Light sensitivity of the a-Si:H sheet resistance was minimized and the surface resistivity was successfully` controlled in the range of 10{sup 12} {approximately} 10{sup 17} {Omega}/{four_gradient} by carbon alloying and boron doping. Performance of the detectors with boron-doped a-Si:C:H layers was comparable to that of electronic-conducting glass. Hydrogen dilution of silane has been explored to improve electrical transport properties of a-Si:H material for high speed photo-detectors and TFT applications.

  15. Comparative study of UV radiation hardness of n+p and p+n duo-lateral position sensitive detectors

    NASA Astrophysics Data System (ADS)

    Xerviar Esebamen, Omeime; Thungström, Göran; Nilsson, Hans-Erik; Lundgren, Anders

    2014-11-01

    We report experimental results on the degree of radiation damage in two duo-lateral position sensitive detectors (LPSDs) exposed to 193 nm and 253 nm ultraviolet (UV) beam. One of the detectors was an in-house fabricated n+p LPSD and the other was a commercially available p+n LPSD. We report that at both wavelengths, the degradation damage from the UV photons absorption caused a much more significant deterioration in responsivity in the p+n LPSD than in the n+p LPSD. By employing a simple method, we were able to visualize the radiation damage on the active area of the LPSDs using 3-dimensional graphs. We were also able to characterize the impact of radiation damage on the linearity and position error of the detectors.

  16. Neutron Radiation Shielding For The NIF Streaked X-Ray Detector (SXD) Diagnostic

    SciTech Connect

    Song, P; Holder, J; Young, B; Kalantar, D; Eder, D; Kimbrough, J

    2006-11-02

    The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) is preparing for the National Ignition Campaign (NIC) scheduled in 2010. The NIC is comprised of several ''tuning'' physics subcampaigns leading up to a demonstration of Inertial Confinement Fusion (ICF) ignition. In some of these experiments, time-resolved x-ray imaging of the imploding capsule may be required to measure capsule trajectory (shock timing) or x-ray ''bang-time''. A capsule fueled with pure tritium (T) instead of a deutriun-tritium (DT) mixture is thought to offer useful physics surrogacy, with reduced yields of up to 5e14 neutrons. These measurements will require the use of the NIF streak x-ray detector (SXD). The resulting prompt neutron fluence at the planned SXD location ({approx}1.7 m from the target) would be {approx}1.4e9/cm{sup 2}. Previous measurements suggest the onset of significant background at a neutron fluence of {approx} 1e8/cm{sup 2}. The radiation damage and operational upsets which starts at {approx}1e8 rad-Si/sec must be factored into an integrated experimental campaign plan. Monte Carlo analyses were performed to predict the neutron and gamma/x-ray fluences and radiation doses for the proposed diagnostic configuration. A possible shielding configuration is proposed to mitigate radiation effects. The primary component of this shielding is an 80 cm thickness of Polyethylene (PE) between target chamber center (TCC) and the SXD diagnostic. Additionally, 6-8 cm of PE around the detector provide from the large number of neutrons that scatter off the inside of the target chamber. This proposed shielding configuration reduces the high-energy neutron fluence at the SXD by approximately a factor {approx}50.

  17. In vivo dosimetry for gynaecological brachytherapy using a novel position sensitive radiation detector: Feasibility study

    SciTech Connect

    Reniers, B.; Landry, G.; Eichner, R.; Hallil, A.; Verhaegen, F.

    2012-04-15

    Purpose: In gynecological radiotherapy with high dose rate (HDR){sup 192}Ir brachytherapy, the treatment complexity has increased due to improved optimization techniques and dose constraints. As a consequence, it has become more important to verify the dose delivery to the target and also to the organs at risk (e.g., the bladder). In vivo dosimetry, where dosimeters are placed in or on the patient, is one way of verifying the dose but until recently this was hampered by motion of the radiation detectors with respect to the source. The authors present a novel dosimetry method using a position sensitive radiation detector. Methods: The prototype RADPOS system (Best Medical Canada) consists of a metal oxide field effect transistor (MOSFET) dosimeter coupled to a position-sensor, which deduces its 3D position in a magnetic field. To assess the feasibility of in vivo dosimetry based on the RADPOS system, different characteristics of the detector need to be investigated. Using a PMMA phantom, the positioning accuracy of the RADPOS system was quantified by comparing position readouts with the known position of the detector along the x and y-axes. RADPOS dose measurements were performed at various distances from a Nucletron{sup 192}Ir source in a PMMA phantom to evaluate the energy dependence of the MOSFET. A sensitivity analysis was performed by calculating the dose after varying (1) the position of the RADPOS detector to simulate organ motion and (2) the position of the first dwell position to simulate errors in delivery. The authors also performed an uncertainty analysis to determine the action level (AL) that should be used during in vivo dosimetry. Results: Positioning accuracy is found to be within 1 mm in the 1-10 cm range from the origin along the x-axis (away from the transmitter), meeting the requirements for in vivo dosimetry. Similar results are obtained for the other axes. The ALs are chosen to take into account the total uncertainty on the measurements. As a consequence for in vivo dosimetry, it is determined that the RADPOS sensor, if placed, for example, in the bladder Foley balloon, would detect a 2 mm motion of the bladder, at a 5% chance of a false positive, with an AL limit of 9% of the dose delivered. The authors found that source position errors, caused by, e.g., a wrong first dwell position, are more difficult to detect; indeed, with our single RADPOS detector, positioned in the bladder, dwell position errors below 5 mm and resulting in a dose error within 10%, could be detected in the tandem but not in the colpostats. A possible solution to improve error detection is to use multiple MOSFETs to obtain multiple dose values. Conclusions: In this study, the authors proposed a dosimetry procedure, based on the novel RADPOS system, to accurately determine the position of the radiation dosimeter with respect to the applicator. The authors found that it is possible to monitor the delivered dose in a point and compare it to the predetermined dose. This allows in principle the detection of problems such as bladder motion/filling or source mispositioning. Further clinical investigation is warranted.

  18. Multi-parameter high-resolution spatial maps of a CdZnTe radiation detector array

    SciTech Connect

    N. R. Hilton; H. B. Barber; B. A. Brunett; J. D. Eskin; M. S. Goorsky; R. B. James; J. C. Lund; D. G. Marks; T. E. Schlesinger; T. M.Teska; J. M. Van Scyoc; J.M. Woolfenden; H. Yoon

    1998-11-07

    Resistivity results from a 48x48 pixelated CdZnTe (CZT) radiation detector array are presented alongside X-ray topography and detector mapping with a collimated gamma-ray beam. By using a variety of measurements performed on the same sample and registering each data set relative to the others, the spatial dependence of relationships between them was examined. The local correlations between resistivity and one measure of detector performance were strongly influenced by the positions of grain boundaries and other gross crystal defects in the sample. These measurements highlight the need for material studies of spatially heterogeneous CZT to record position information along with the parameters under study.

  19. Diurnal variations of energetic particle radiation at the surface of Mars as observed by the Mars Science Laboratory Radiation Assessment Detector

    NASA Astrophysics Data System (ADS)

    Rafkin, Scot C. R.; Zeitlin, Cary; Ehresmann, Bent; Hassler, Don; Guo, Jingnan; Köhler, Jan; Wimmer-Schweingruber, Robert; Gomez-Elvira, Javier; Harri, Ari-Matti; Kahanpää, Henrik; Brinza, David E.; Weigle, Gerald; Böttcher, Stephan; Böhm, Eckart; Burmeister, Söenke; Martin, Cesar; Reitz, Güenther; Cucinotta, Francis A.; Kim, Myung-Hee; Grinspoon, David; Bullock, Mark A.; Posner, Arik

    2014-06-01

    The Radiation Assessment Detector onboard the Mars Science Laboratory rover Curiosity is detecting the energetic particle radiation at the surface of Mars. Data collected over the first 350 Martian days of the nominal surface mission show a pronounced diurnal cycle in both the total dose rate and the neutral particle count rate. The diurnal variations detected by the Radiation Assessment Detector were neither anticipated nor previously considered in the literature. These cyclic variations in dose rate and count rate are shown to be the result of changes in atmospheric column mass driven by the atmospheric thermal tide that is characterized through pressure measurements obtained by the Rover Environmental Monitoring Station, also onboard the rover. In addition to bulk changes in the radiation environment, changes in atmospheric shielding forced by the thermal tide are shown to disproportionately affect heavy ions compared to H and He nuclei.

  20. Transition from image intensifier to flat panel detector in interventional cardiology: Impact of radiation dose.

    PubMed

    Livingstone, Roshan S; Chase, David; Varghese, Anna; George, Paul V; George, Oommen K

    2015-01-01

    Flat panel detector (FPD) technology in interventional cardiology is on the increase due to its varied advantages compared to the conventional image intensifier (II) systems. It is not clear whether FPD imparts lower radiation doses compared to II systems though a few studies support this finding. This study intends to compare radiation doses from II and FPD systems for coronaryangiography (CAG) and Percutaneous Transluminal Coronary Angioplasty (PTCA) performed in a tertiary referral center. Radiation doses were measured using dose area product (DAP) meter from patients who underwent CAG (n = 222) and PTCA (n = 75) performed using FPD angiography system. The DAP values from FPD were compared with earlier reported data using II systems from the same referral center where the study was conducted. The mean DAP values from FPD system for CAG and PTCA were 24.35 and 63.64 Gycm(2) and those from II system were 27.71 and 65.44 Gycm(2). Transition from II to FPD system requires stringent dose optimization strategies right from the initial period of installation. PMID:26150684

  1. Transition from image intensifier to flat panel detector in interventional cardiology: Impact of radiation dose

    PubMed Central

    Livingstone, Roshan S.; Chase, David; Varghese, Anna; George, Paul V.; George, Oommen K.

    2015-01-01

    Flat panel detector (FPD) technology in interventional cardiology is on the increase due to its varied advantages compared to the conventional image intensifier (II) systems. It is not clear whether FPD imparts lower radiation doses compared to II systems though a few studies support this finding. This study intends to compare radiation doses from II and FPD systems for coronaryangiography (CAG) and Percutaneous Transluminal Coronary Angioplasty (PTCA) performed in a tertiary referral center. Radiation doses were measured using dose area product (DAP) meter from patients who underwent CAG (n = 222) and PTCA (n = 75) performed using FPD angiography system. The DAP values from FPD were compared with earlier reported data using II systems from the same referral center where the study was conducted. The mean DAP values from FPD system for CAG and PTCA were 24.35 and 63.64 Gycm2 and those from II system were 27.71 and 65.44 Gycm2. Transition from II to FPD system requires stringent dose optimization strategies right from the initial period of installation. PMID:26150684

  2. A Low-Power, Radiation-Resistant, Silicon-Drift-Detector Array for Extraterrestrial Element Mapping

    SciTech Connect

    Ramsey B. D.; De Geronimo G.; Gaskin, J.A.; Elsner, R.F.; Chen, W.; Carini, G.A.; Keister, J.; Li, S.; Li, Z.; Siddons, D.P.; Smith, G.

    2012-02-08

    We are developing a modular Silicon Drift Detector (SDD) X-Ray Spectrometer (XRS) for measuring the abundances of light surface elements (C to Fe) fluoresced by ambient radiation on remote airless bodies. The value of fluorescence spectrometry for surface element mapping is demonstrated by its inclusion on three recent lunar missions and by exciting new data that have recently been announced from the Messenger Mission to Mercury. The SDD-XRS instrument that we have been developing offers excellent energy resolution and an order of magnitude lower power requirement than conventional CCDs, making much higher sensitivities possible with modest spacecraft resources. In addition, it is significantly more radiation resistant than x-ray CCDs and therefore will not be subject to the degradation that befell recent lunar instruments. In fact, the intrinsic radiation resistance of the SDD makes it applicable even to the harsh environment of the Jovian system where it can be used to map the light surface elements of Europa. In this paper, we first discuss our element-mapping science-measurement goals. We then derive the necessary instrument requirements to meet these goals and discuss our current instrument development status with respect to these requirements.

  3. Study of Rare Radiative B Decay to K*(1430) Meson Using the BABAR Detector

    SciTech Connect

    Guo, Qinghua; /Pennsylvania U.

    2005-09-14

    Radiative B Meson decay through the b {yields} s{gamma} process has been one of the most sensitive probe of new physics beyond the Standard Model, because of its importance in understanding the phenomenon of CP violation, which is believed to be necessary to explain the excess of matter over anti-matter in our universe. The inclusive picture of the b {yields} s{gamma} process is well established; however, our knowledge of the exclusive final states in radiative B meson decays is rather limited. We have investigated one of them, the exclusive, radiative B decay to the charmless K*{sub 2}(1430) meson, in a sample of 88.5 x 10{sup 6} B{bar B} events with the BABAR detector at the PEP-II storage ring. We present a measurement of the branching fractions {Beta}(B{sup 0} {yields} K*{sub 2}(1430){sup 0}{gamma}) = (1.22 {+-} 0.25 {+-} 0.10) x 10{sup -5} and {Beta}(B{sup +} {yields} K*{sub 2}(1430){sup +}){gamma} = (1.45 {+-} 0.40 {+-} 0.15) x 10{sup -5}, where the first error is statistical and the second systematic. In addition, we have performed the first search for direct CP violation in this decay with the measured asymmetry in B{sup 0} {yields} K*{sub 2}(1430){sup 0}{gamma} of {Alpha}{sub CP} = -0.08 {+-} 0.15 {+-} 0.01.

  4. 8-Gbps-per-channel radiation-tolerant VCSEL drivers for the LHC detector upgrade

    NASA Astrophysics Data System (ADS)

    Li, X.; Guo, D.; Chen, J.; Gong, D.; Hou, S.; Huang, D.; Huang, G.; Liang, F.; Liu, C.; Liu, T.; Sun, X.; Teng, P.-K.; Xiang, A. C.; Ye, J.; You, Y.; Zhao, X.

    2015-02-01

    We present ASIC designs of VCSEL drivers for a single VCSEL (LOCld1), two individual VCSELs (LOCld2) and a four-channel VCSEL array (LOCld4). This work is for new detector readout systems needed in the Large Hadron Collider upgrade program. All ASICs are fabricated in a commercial 0.25-? m Silicon-on-Sapphire CMOS technology. LOCld1 and LOCld2 have passed the 8-Gbps and 10-Gbps eye mask tests. Operating at 8 Gbps data rate, the measured total jitter of LOCld1 and LOCld2 is less than 30 ps, and the power comsuption is about 200 mW per channel with 6-mA bias current and 6.4-mA modulation current. The radiation tolerance of LOCld1 has been qualified with x-ray and high-energy neutron beam test.

  5. Cosmic Ray Test of Mini-drift Thick Gas Electron Multiplier Chamber for Transition Radiation Detector

    E-print Network

    S. Yang; S. Das; B. Buck; C. Li; T. Ljubicic; R. Majka; M. Shao; N. Smirnov; G. Visser; Z. Xu; Y. Zhou

    2015-02-17

    A thick gas electron multiplier (THGEM) chamber with an effective readout area of 10$\\times$10 cm$^{2}$ and a 11.3 mm ionization gap has been tested along with two regular gas electron multiplier (GEM) chambers in a cosmic ray test system. The thick ionization gap makes the THGEM chamber a mini-drift chamber. This kind mini-drift THGEM chamber is proposed as part of a transition radiation detector (TRD) for identifying electrons at an Electron Ion Collider (EIC) experiment. Through this cosmic ray test, an efficiency larger than 94$\\%$ and a spatial resolution $\\sim$220 $\\mu$m are achieved for the THGEM chamber at -3.65 kV. Thanks to its outstanding spatial resolution and thick ionization gap, the THGEM chamber shows excellent track reconstruction capability. The gain uniformity and stability of the THGEM chamber are also presented.

  6. Method and apparatus for electron-only radiation detectors from semiconductor materials

    DOEpatents

    Lund, James C. (429 Warwick Ave., San Leandro, CA 94577)

    2000-01-01

    A system for obtaining improved resolution in room temperature semiconductor radiation detectors such as CdZnTe and Hgl.sub.2, which exhibit significant hole-trapping. A electrical reference plane is established about the perimeter of a semiconductor crystal and disposed intermediately between two oppositely biased end electrodes. The intermediate reference plane comprises a narrow strip of wire in electrical contact with the surface of the crystal, biased at a potential between the end electrode potentials and serving as an auxiliary electrical reference for a chosen electrode--typically the collector electrode for the more mobile charge carrier. This arrangement eliminates the interfering effects of the less mobile carriers as these are gathered by their electrode collector.

  7. Development of Micro and Nano Crystalline CVD Diamond TL/OSL Radiation Detectors for Clinical Applications

    NASA Astrophysics Data System (ADS)

    Barboza-Flores, Marcelino

    2015-03-01

    Modern radiotherapy methods requires the use of high photon radiation doses delivered in a fraction to small volumes of cancer tumors. An accurate dose assessment for highly energetic small x-ray beams in small areas, as in stereotactic radiotherapy, is necessary to avoid damage to healthy tissue surrounding the tumor. Recent advances on the controlled synthesis of CVD diamond have demonstrated the possibility of using high quality micro and nano crystalline CVD as an efficient detector and dosimeter suitable for high energy photons and energetic particle beams. CVD diamond is a very attractive material for applications in ionizing radiation dosimetry, particularly in the biomedical field since the radiation absorption by a CVD diamond is very close to that of soft tissue. Furthermore, diamond is stable, non-toxic and radiation hard. In the present work we discuss the CVD diamond properties and dosimeter performance and discuss its relevance and advantages of various dosimetry methods, including thermally stimulated luminescence (TL) as well as optically stimulated luminescence (OSL). The recent CVD improved method of growth allows introducing precisely controlled impurities into diamond to provide it with high dosimetry sensitivity. For clinical dosimetry applications, high accuracy of dose measurements, low fading, high sensitivity, good reproducibility and linear dose response characteristics are very important parameters which all are found in CVD diamonds specimens. In some cases, dose linearity and reproducibility in CVD diamond have been found to be higher than standard commercial TLD materials like LiF. In the present work, we discuss the state-of-the art developments in dosimetry applications using CVD diamond. The financial support from Conacyt (Mexico) is greatly acknowledged

  8. Study of the radiation damage on Ge detectors and background for CAGRAF

    NASA Astrophysics Data System (ADS)

    Ichige, Natsumi; Aoi, Nori; Ayyad, Yassid; Ideguchi, Eiji; Iwamoto, Chihiro; Koike, Takeshi; Suzuki, Hirotaka; Suzuki, Tomokazu; Tamii, Atsushi; Tanaka, Mana; Yamamoto, Tetsuya; Yamamoto, Yasutaka; Cagra Collaboration

    2014-09-01

    CAGRA, jointly developed between the U.S. and Japan, is an array of 16 Clover-type Ge detectors with anti-Compton BGO shields. RCNP is one of the main hosts to CAGRA. A project called CAGRAF is started at RCNP where the high resolution reaction spectrometer Grand Raiden is considered to be coupled with CAGRA. A critical issue for this setup is a severity of radiation damages mainly caused by fast neutrons which would be produced in primary beams of a few-hundred-MeV proton. To investigate the degree of the neutron damages and background in the Ge energy spectrum, a test experiment was conducted at the Grand Raiden beam line at RCNP in May, 2014. Two sets of plastic and liquid scintillator counters are placed near a 12C target (30 mg/cm2) for measurements of neutron flux from the p + 12C reaction with the beam energy of 392 MeV. The beam intensity is varied between 1 nA-10 nA. One transistor reset-type Ge detector is placed at 10 cm or 50 cm away from the target center. The Ge energy spectra are taken with the CAGRA digital electronics. In this contribution, results of the test experiment will be presented.

  9. Homogenization theory for the cumulative effect of Te inclusions in CdZnTe radiation detectors

    NASA Astrophysics Data System (ADS)

    Bale, Derek S.

    2010-01-01

    In this paper, homogenization theory based on a multiple scale perturbation of the charge-transport equation is used to derive a mathematical framework for modeling the cumulative effect of Te inclusions in radiation detectors based on semi-insulating cadmium zinc telluride (CdZnTe). The derived framework naturally incorporates a wide range of physical models that may posit either a reduced electron lifetime due to enhanced trapping at inclusions, or an altered carrier speed due to a distorted electric field at inclusions, or both. The new framework is applied to a simplified version of the geometric model introduced by Bolotnikov et al. [Nucl. Instrum. Methods Phys. Res. A 571, 687 (2007)], and it is shown that this results in a closed-form approximation to the reduced electron trapping time that depends in a rather simple way on fundamental inclusion parameters such as their mean size and number density. It is also demonstrated that this effective trapping time compares well with previously published simulation data for the geometric model. Further, the electron mobility-lifetime product that results from the reduced carrier lifetime is easily incorporated into Monte Carlo device simulation. Examples of simulated induction maps and pulse-height spectra for pixelated detectors that contain inclusions of various mean sizes and number densities are presented.

  10. Calibration of a liquid xenon gamma ray detector for the study of radiative pion decay

    NASA Astrophysics Data System (ADS)

    Bressi, G.; Carugno, G.; Cerdonio, S.; Conti, E.; Meneguzzo, A. T.; Zanello, D.

    1997-02-01

    The performance of a liquid xenon time projection chamber as a detector for gamma rays between 0 and 30 MeV has been studied by comparing data collected with radioactive sources to a Monte Carlo simulation. The detector was designed for the study of the pion radiative decay. Both the scintillation light and the ionization charge signals were exploited. The light signals were used in the trigger logic and for the measurement of the chamber trigger acceptance. The minimum triggerable energy turned out to be 170 keV. The charge signals were used to measure the gamma ray energy. The noise introduced by the electronics was about 140 keV and the minimum measurable energy 230 keV with an electric drift field of 0.5 kV/cm. All the charge and light spectra were in good agreement with the simulation. The overall apparatus acceptance, taking into account geometry, trigger efficiency and offline reconstruction losses, was independent of the gamma ray energy above 2 MeV and equal to 10%.

  11. Current response of a TlBr detector to {sup 137}Cs {gamma}-ray radiation

    SciTech Connect

    Gazizov, I. M.; Zaletin, V. M.; Kukushkin, V. M.; Khrunov, V. S.

    2011-05-15

    The current response of a TlBr detector to {sup 137}Cs {gamma}-ray radiation has been studied in the dose-rate range 0.033-3.84 Gy/min and within the voltage range 1-300 V; the detectors are based on pure and doped TlBr crystals grown from the melt by the Bridgman-Stockbarger method. The mass fraction of Pb or Ca introduced into the TlBr crystals was 1-10 ppm for Pb and 150 ppm for Ca. The current response of nominally undoped TlBr samples was nearly linear over two decades of studied dose rates. Deep hole levels associated with cationic vacancies V{sub c}{sup -} determine the dependence of the current response on the voltage in the high electric fields. The parameters of the carriers' transport {mu}{tau} are determined. The TlBr crystals grown in vacuum and in the bromine vapor exhibit a large mobility-lifetime product of 4.3 Multiplication-Sign 10{sup -4} and 6.4 Multiplication-Sign 10{sup -5} cm{sup 2}V{sup -1}, respectively. The value of {mu}{tau} is in the range (4-9) Multiplication-Sign 10{sup -5} cm{sup 2}V{sup -1} for crystals doped with a divalent cation.

  12. Elementary analysis of line shapes and energy resolution in semiconductor radiation detectors

    SciTech Connect

    Toney, J.E.; Schlesinger, T.E.; Brunett, B.A.; James, R.B.

    1998-12-31

    The authors have used an elementary statistical technique to derive a closed-form expression for the hole-tailing line shape produced by photoelectric absorption of monoenergetic radiation in a semiconductor X-ray/{gamma}-ray detector. In the case of compound semiconductors, where the drift length for electrons is much greater than that for holes, the line shape is given by a type of power law, except for a small region very near the photopeak. This analytical result agrees well with Monte Carlo simulations and is used to extract approximate {mu}{tau} products from a {sup 57}Co pulse height spectrum. They also present an expression for the maximum obtainable energy resolution of a semiconductor detector in the presence of leakage current noise and intrinsic statistical fluctuations as a function of material parameters, along with a chart of the optimal band gap as a function of temperature and photon energy. Based on these considerations, the optimal band gap for room-temperature operation is approximately 2.0 eV.

  13. SU-E-T-553: Characterization of Plastic Scintillator Detectors for Radiation Therapy

    SciTech Connect

    Liu, H; Lin, H; Darafsheh, A; Finlay, J; Both, S; Zhu, T

    2014-06-01

    Purpose: To characterize basic performance of plastic scintillator detectors (PSD) designed for dosimetry of radiation therapy. Methods: The Exradin W1 Scintillator is a plastic scintillating fiber-based detector designed for highly accurate measurement of small radiotherapy fields used in patient plan verification and machine commissioning and QA procedures. The Cerenkov emissions were corrected using spectral separation. The optical signal was converted to electronic signal with a photodiode. We measured its dosimetry performance, including percentage depth dose, output factor, dose and dose rate linear response. We compared the dosimetry results with reference ion chamber measurements. Results: The dosimetry results of PSD agree well with reference ion chamber measurements. For percentage depth dose, the differences between PSD and ion chamber results are on average 1.7±1.1% and 0.8±0.8% with a maximum of 3.5% and 2.7% for 6MV and 15MV beams, respectively. For the output factors, PSD measurements are within 2% from ion chamber results. The dose linear response is within 1% when dose is larger than 20 MU for both 6 MV and 15 MV. The dose rate linear response is within 1% for the entire dose rate used (100 MU/min to 600MU/min). Conclusions: The current design of PSD is feasible for the dosimtry measurement in radiation therapy. This combination of PSD and photodiode system could be extended to multichannel array detection of dose distribution. It might as well be used as range verification in proton therapy. The work is partially supported by: DOD (W81XWH-09-2-0174) and American Cancer Society (IRG-78-002-28)

  14. Responses of conventional and extended-range neutron detectors in mixed radiation fields around a 150-MeV electron LINAC

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Chi; Sheu, Rong-Jiun; Chen, Ang-Yu

    2015-01-01

    This study analyzed the responses of two types of neutron detector in mixed gamma-ray and neutron radiation fields around a 150-MeV electron linear accelerator (LINAC). The detectors were self-assembled, high efficiency, and designed in two configurations: (1) a conventional moderated-type neutron detector based on a large cylindrical He-3 proportional counter; and (2) an extended-range version with an embedded layer of lead in the moderator to increase the detector's sensitivity to high-energy neutrons. Two sets of the detectors were used to measure neutrons at the downstream and lateral locations simultaneously, where the radiation fields differed considerably in intensities and spectra of gamma rays and neutrons. Analyzing the detector responses through a comparison between calculations and measurements indicated that not only neutrons but also high-energy gamma rays (>5 MeV) triggered the detectors because of photoneutrons produced in the detector materials. In the lateral direction, the contribution of photoneutrons to both detectors was negligible. Downstream of the LINAC, where high-energy photons were abundant, photoneutrons contributed approximately 6% of the response of the conventional neutron detector; however, almost 50% of the registered counts of the extended-range neutron detector were from photoneutrons because of the presence of the detector rather than the effect of the neutron field. Dose readings delivered by extended-range neutron detectors should be interpreted cautiously when used in radiation fields containing a mixture of neutrons and high-energy gamma rays.

  15. Design of a synchrotron radiation detector for the test beam lines at the Superconducting Super Collider Laboratory

    SciTech Connect

    Hutton, R.D.

    1994-01-01

    As part of the particle- and momentum-tagging instrumentation required for the test beam lines of the Superconducting Super Collider (SSC), the synchrotron radiation detector (SRD) was designed to provide electron tagging at momentum above 75 GeV. In a parallel effort to the three test beam lines at the SSC, schedule demands required testing and calibration operations to be initiated at Fermilab. Synchrotron radiation detectors also were to be installed in the NM and MW beam lines at Femilab before the test beam lines at the SSC would become operational. The SRD is the last instrument in a series of three used in the SSC test beam fines. It follows a 20-m drift section of beam tube downstream of the last silicon strip detector. A bending dipole just in of the last silicon strip detector produces the synchrotron radiation that is detected in a 50-mm-square cross section NaI crystal. A secondary scintillator made of Bicron BC-400 plastic is used to discriminate whether it is synchrotron radiation or a stray particle that causes the triggering of the NaI crystal`s photo multiplier tube (PMT).

  16. Search for charmless decays of B hadrons in hadronic and radiative modes using the DELPHI detector at LEP

    NASA Astrophysics Data System (ADS)

    Battaglia, M.; Katsanevas, S.; Liko, D.; Nikolaidou, R.

    1996-02-01

    Charmless hadronic decay of beauty particles can proceed through both tree level diagrams involving b ? u transitions and penguin processes. Radiative (b ? s ?) decays are pure penguin processes. These decays are of special interest as a test of the loop structure of the standard model and in connection with the measurement of CP violation in the B sector. A search for charmless hadronic and radiative decays of B mesons has been performed with the DELPHI detector at the LEP collider. The high tracking resolution, obtained with the silicon microvertex detector, provides efficient b-tagging and rejection of combinatorial background. In addition, the particle identification capabilities of the DELPHI ring imaging Cherenkov detector allow the separation of channels with a kaon from the pure multi-pion final states.

  17. Thin silicon strip detectors for beam monitoring in Micro-beam Radiation Therapy

    NASA Astrophysics Data System (ADS)

    Povoli, M.; Alagoz, E.; Bravin, A.; Cornelius, I.; Bräuer-Krisch, E.; Fournier, P.; Hansen, T. E.; Kok, A.; Lerch, M.; Monakhov, E.; Morse, J.; Petasecca, M.; Requardt, H.; Rosenfeld, A. B.; Röhrich, D.; Sandaker, H.; Salomé, M.; Stugu, B.

    2015-11-01

    Microbeam Radiation Therapy (MRT) is an emerging cancer treatment that is currently being developed at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. This technique uses a highly collimated and fractionated X-ray beam array with extremely high dose rate and very small divergence, to benefit from the dose-volume effect, thus sparing healthy tissue. In case of any beam anomalies and system malfunctions, special safety measures must be installed, such as an emergency safety shutter that requires continuous monitoring of the beam intensity profile. Within the 3DMiMic project, a novel silicon strip detector that can tackle the special features of MRT, such as the extremely high spatial resolution and dose rate, has been developed to be part of the safety shutter system. The first prototypes have been successfully fabricated, and experiments aimed to demonstrate their suitability for this unique application have been performed. Design, fabrication and the experimental results as well as any identified inadequacies for future optimisation are reported and discussed in this paper.

  18. Gd2O3:Eu3+/PPO/POPOP/PS composites for digital imaging radiation detectors

    NASA Astrophysics Data System (ADS)

    Oliveira, J.; Martins, P. M.; Martins, P.; Correia, V.; Rocha, J. G.; Lanceros-Mendez, S.

    2015-11-01

    Polymer-based scintillator composites have been produced by combining polystyrene (PS) and Gd2O3:Eu3+ scintillator nanoparticles. Polystyrene has been used since it is a flexible and stable binder matrix, resistant to thermal and light deterioration and with suitable optical properties. Gd2O3:Eu3+ has been selected as scintillator material due to its wide band gap, high density and visible light yield. The optical, thermal and electrical characteristics of the composites were studied as a function of filler content, together with their performance as scintillator material. Additionally 1 wt.% of 2,5-diphenyloxazole (PPO) and 0.01 wt.% of 1,4 di[2-(5phenyloxazolyl)]benzene (POPOP) were introduced in the polymer matrix in order to strongly improve light yield, i.e., the measured intensity of the output visible radiation, under X-ray irradiation. Increasing scintillator filler concentration (from 0.25 to 7.5 wt.%) increases scintillator light yield and decreases the optical transparency of the composite. The addition of PPO and POPOP strongly increased the overall transduction performance of the composite due to specific absorption and re-emission processes. It is thus shown that Gd2O3:Eu3+/PPO/POPOP/PS composites with 0.25 wt.% of scintillator content with fluorescence molecules are suitable for the development of innovative large-area X-ray radiation detectors with huge demand from the industries.

  19. Comparison of dose accuracy between film and two-dimensional detectors in intensity-modulated radiation therapy

    NASA Astrophysics Data System (ADS)

    Onishi, Yuichi; Nakayama, Shinichi; Watanabe, Shinsaku; Kaneshige, Souichirou; Monzen, Hajime; Matsumoto, Kenji; Shintani, Naoya; Kamomae, Takeshi

    2015-07-01

    We constructed seven intensity-modulated radiation therapy (IMRT) treatment plans for prostate cancer (49 irradiation fields which contained seven randomly-sampled patients and seven fields) and evaluated the dose distributions by using a radiochromic film (EBT3 film) and a 2D detector. We superposed the calculated dose distribution of the IMRT treatment plan on EBT3 film and the 2D detector results and then compared those with the ?-analysis pass rate. The relative positions of the beam and the detector were varied; the results of the analysis of the superior-inferior (SI) direction potentially differed, depending on the detector position, under an irradiation beam with the same fluence map. The detector was moved over a range of' 8 mm in the SI direction in 1-mm step increments, measurement were made at each position, and the results were analyzed. The ?-analysis compared the dose distributions from EBT3 film and the radiation treatment planning system (RTPS) for each patient and field; the pass rate with the ?-analysis from 98 to 100% was 2.04%. When we compared the dose distributions of the 2D detector and the RTPS, the pass rate from 98 to 100% was 63.2%. The mean values for the ?-analysis pass rates for EBT3 film and the 2D detector were 94.2 and 97.6%, respectively. Volume averaging of the data indicated a mean pass rate and standard deviation of 98.6 and 0.91%, respectively, and a pass rate of more than 96% for all positions. A 2D detector can, therefore, be used as an alternative apparatus for IMRT dose verification.

  20. Spatial and spectral gamma-ray response of plastic scintillators used in portal radiation detectors; comparison of measurements and simulations

    NASA Astrophysics Data System (ADS)

    Takoudis, G.; Xanthos, S.; Clouvas, A.; Antonopoulos-Domis, M.; Potiriadis, C.; Silva, J.

    2009-02-01

    Portal radiation detectors are commonly used by steel industries in the probing and detection of radioactivity contamination in scrap metal. Furthermore, a large number of portal monitors are installed at the border crossings to prevent illegal radioactive material trafficking. These portal detectors typically consist of either PS (polystyrene) or PVT (polyvinyltoluene) plastic scintillating detectors. Through the electronic circuit of the detector, an energy region-of-interest window can be determined in order to focus on the detection of certain radionuclides. In this study, the spatial response of a portal's PS scintillator to a Cs-137 and a Co-60 source for various energy region-of-interest windows is presented. Furthermore, a number of measured spectra for different source positions on the surface of the scintillating detector are shown. The measured spatial response showed a quantitative and qualitative dependence on the energy window used each time. In addition, measured spectra showed energy shifts for different positions of the two sources on the detector surface. The aforementioned phenomena could not be adequately explained and modelled using gamma-particle transport Monte Carlo simulation tools, such as the MCNP4C2 code. In order to fully explain these phenomena, we performed optical simulations, modelling the transport of the light yield within the detector, using Gate v3.0.0 with Geant 4.8.0p01 of CERN. The results of those simulations are presented and compared to the measured ones.

  1. An experiment to distinguish between diffusive and specular surfaces for thermal radiation in cryogenic gravitational-wave detectors

    NASA Astrophysics Data System (ADS)

    Sakakibara, Yusuke; Kimura, Nobuhiro; Suzuki, Toshikazu; Yamamoto, Kazuhiro; Tokoku, Chihiro; Uchiyama, Takashi; Kuroda, Kazuaki

    2015-07-01

    In cryogenic gravitational-wave detectors, one of the most important issues is the fast cooling of their mirrors and keeping them cool during operation to reduce thermal noise. For this purpose, the correct estimation of thermal-radiation heat transfer through the pipe-shaped radiation shield is vital to reduce the heat load on the mirrors. However, the amount of radiation heat transfer strongly depends on whether the surfaces reflect radiation rays diffusely or specularly. Here, we propose an original experiment to distinguish between diffusive and specular surfaces. This experiment has clearly shown that the examined diamond-like carbon-coated surface is specular. This result emphasizes the importance of suppressing the specular reflection of radiation in the pipe-shaped shield.

  2. Growth of CdZnTe Crystals for Radiation Detector Applications by Directional Solidification

    NASA Technical Reports Server (NTRS)

    Su, Ching-Hua

    2014-01-01

    Advances in Cadmium Zinc Telluride (Cd(sub 1-x)Zn(sub x)Te) growth techniques are needed for the production of large-scale arrays of gamma and x-ray astronomy. The research objective is to develop crystal growth recipes and techniques to obtain large, high quality CdZnTe single crystal with reduced defects, such as charge trapping, twinning, and tellurium precipitates, which degrade the performance of CdZnTe and, at the same time, to increase the yield of usable material from the CdZnTe ingot. A low gravity material experiment, "Crystal Growth of Ternary Compound Semiconductors in Low Gravity Environment", will be performed in the Material Science Research Rack (MSRR) on International Space Station (ISS). One section of the flight experiment is the melt growth of CdZnTe ternary compounds. This talk will focus on the ground-based studies on the growth of Cd(sub 0.80)Zn(sub 0.20)Te crystals for radiation detector applications by directional solidification. In this investigation, we have improved the properties that are most critical for the detector applications (electrical properties and crystalline quality): a) Electrical resistivity: use high purity starting materials (with reproducible impurity levels) and controlled Cd over pressure during growth to reproducibly balance the impurity levels and Cd vacancy concentration b) Crystalline quality: use ultra-clean growth ampoule (no wetting after growth), optimized thermal profile and ampoule design, as well as a technique for supercool reduction to growth large single crystal with high crystalline quality

  3. Radiation dose assessment in a 320-detector-row CT scanner used in cardiac imaging

    SciTech Connect

    Goma, Carles; Ruiz, Agustin; Jornet, Nuria; Latorre, Artur; Pallerol, Rosa M.; Carrasco, Pablo; Eudaldo, Teresa; Ribas, Montserrat

    2011-03-15

    Purpose: In the present era of cone-beam CT scanners, the use of the standardized CTDI{sub 100} as a surrogate of the idealized CTDI is strongly discouraged and, consequently, so should be the use of the dose-length product (DLP) as an estimate of the total energy imparted to the patient. However, the DLP is still widely used as a reference quantity to normalize the effective dose for a given scan protocol mainly because the CTDI{sub 100} is an easy-to-measure quantity. The aim of this article is therefore to describe a method for radiation dose assessment in large cone-beam single axial scans, which leads to a straightforward estimation of the total energy imparted to the patient. The authors developed a method accessible to all medical physicists and easy to implement in clinical practice in an attempt to update the bridge between CT dosimetry and the estimation of the effective dose. Methods: The authors used commercially available material and a simple mathematical model. The method described herein is based on the dosimetry paradigm introduced by the AAPM Task Group 111. It consists of measuring the dose profiles at the center and the periphery of a long body phantom with a commercial solid-state detector. A weighted dose profile is then calculated from these measurements. To calculate the CT dosimetric quantities analytically, a Gaussian function was fitted to the dose profile data. Furthermore, the Gaussian model has the power to condense the z-axis information of the dose profile in two parameters: The single-scan central dose, f(0), and the width of the profile, {sigma}. To check the energy dependence of the solid-state detector, the authors compared the dose profiles to measurements made with a small volume ion chamber. To validate the overall method, the authors compared the CTDI{sub 100} calculated analytically to the measurement made with a 100 mm pencil ion chamber. Results: For the central and weighted dose profiles, the authors found a good agreement between the measured dose profile data and the fitted Gaussian functions. The solid-state detector had no energy dependence--within the energy range of interest--and the analytical model succeeded in reproducing the absolute dose values obtained with the pencil ion chamber. For the case of large cone-beam single axial scans, the quantity that better characterizes the total energy imparted to the patient is the weighted dose profile integral (DPI{sub w}). The DPI{sub w} can be easily determined from the two parameters that define the Gaussian functions: f(0) and {sigma}. The authors found that the DLP underestimated the total energy imparted to the patient by more than 20%. The authors also found that the calculated CT dosimetric quantities were higher than those displayed on the scanner console. Conclusions: The authors described and validated a method to assess radiation dose in large cone-beam single axial scans. This method offers a simple and more accurate estimation of the total energy imparted to the patient, thus offering the possibility to update the bridge between CT dosimetry and the estimation of the effective dose for cone-beam CT examinations in radiology, nuclear medicine, and radiation therapy.

  4. Characterization of Thallium Bromide (TlBr) for Room Temperature Radiation Detectors

    NASA Astrophysics Data System (ADS)

    Smith, Holland McTyeire

    Thallium bromide (TlBr) has emerged as a remarkably well-suited material for room temperature radiation detection. The unique combination of high-Z elements, high density, suitable band gap, and excellent electrical transport properties present in TlBr have brought device performance up to par with CdZnTe (CZT), the current market-leading room temperature radiation detector material. TlBr research is at an earlier stage than that of CZT, giving hope that the material will see even further improvement in electronic properties. Improving a resistive semiconductor material requires knowledge of deep levels present in the material and the effects of these deep levels on transport properties. Very few deep level studies have been conducted on TlBr, and none with the depth required to generate useful growth suggestions. In this dissertation, deep levels in nominally undoped and doped TlBr samples are studied with electrical and optical methods. Photo-Induced Conductivity Transient Spectroscopy (PICTS) is used to discover many deep levels in TlBr electrically. These levels are compared to sub-band gap optical transitions originating from defects observed in emission spectra. The results of this research indicate that the origin of resistivity in TlBr is likely due to deep level defects pinning the Fermi level at least ˜0.7 eV from either the conduction or valence band edge. The effect of dopants and deep levels on transport in TlBr is assessed with microwave photoconductivity decay analysis. It is found that Pb-, Se-, and O-doping decreases carrier lifetime in TlBr, whereas C-doping does not. TlBr exhibits weak ionic conductivity at room temperature, which both negatively affects the leakage current of detectors and leads to device degradation over time. Researchers are actively looking for ways to reduce or eliminate the ionic conductivity, but are faced with an intriguing challenge of materials engineering: is it possible to mitigate the ionic conduction of TlBr without harming the excellent electronic transport properties? Doping TlBr in order to control the ionic conductivity has been proposed and shown to be effective in reducing dark ionic current, but the electronic effects of the dopants has not been previously studied in detail. In this dissertation, the electronic effects of dopants introduced for ionic reasons are evaluated.

  5. Radiation Response of Forward Biased Float Zone and Magnetic Czochralski Silicon Detectors of Different Geometry for 1-MeV Neutron Equivalent Fluence Monitoring

    E-print Network

    Mekki, J; Dusseau, Laurent; Roche, Nicolas Jean-Henri; Saigne, Frederic; Mekki, Julien; Glaser, Maurice

    2010-01-01

    Aiming at evaluating new options for radiation monitoring sensors in LHC/SLHC experiments, the radiation responses of FZ and MCz custom made silicon detectors of different geometry have been studied up to about 4 x 10(14) n(eq)/cm(2). The radiation response of the devices under investigation is discussed in terms of material type, thickness and active area influence.

  6. Measurements of Coherent Cherenkov Radiation in Rock Salt: Implications for GZK Neutrino Underground Detector

    E-print Network

    Milincic, R; Saltzberg, D; Field, R C; Guillian, G; Walz, D; Williams, D

    2005-01-01

    We report on further SLAC measurements of the Askaryan effect: coherent radio emission from charge asymmetry in electromagnetic cascades. We used synthetic rock salt as the dielectric medium, with cascades produced by GeV bremsstrahlung photons at the Final Focus Test Beam. We extend our prior discovery measurements to a wider range of parameter space and explore the effect in a dielectric medium of great potential interest to large scale ultra-high energy neutrino detectors: rock salt. We observed strong coherent pulsed radio emission over a frequency band from 0.2-15 GHz. A grid of embedded dual-polarization antennas was used to confirm the linear polarization and track the change of direction of the electric-field vector around the shower. Coherence was observed over 4 orders of magnitude of shower energy. The frequency dependence of the radiation was tested over two orders of magnitude of UHF and microwave frequencies. Based on these results we have performed a simulation of a realistic GZK neutrino teles...

  7. Radiation hardness of plastic scintillators for the Tile Calorimeter of the ATLAS detector

    NASA Astrophysics Data System (ADS)

    Jivan, H.; Sideras-Haddad, E.; Erasmus, R.; Liao, S.; Madhuku, M.; Peters, G.; Sekonya, K.; Solvyanov, O.

    2015-10-01

    The radiation damage in polyvinyl toluene based plastic scintillator EJ200 obtained from ELJEN technology was investigated. This forms part of a comparative study conducted to aid in the upgrade of the Tile Calorimeter of the ATLAS detector during which the Gap scintillators will be replaced. Samples subjected to 6 MeV proton irradiation using the tandem accelerator of iThemba LABS, were irradiated with doses of approximately 0.8 MGy, 8 MGy, 25 MGy and 80 MGy. The optical properties were investigated using transmission spectroscopy and light yield analysis whilst structural damage was assessed using Raman spectroscopy. Findings indicate that for the dose of 0.8 MGy, no structural damage occurs and light loss can be attributed to a breakdown in the light transfer between base and fluor dopants. For doses of 8 MGy to 80 MGy, structural damage leads to possible hydrogen loss in the benzene ring of the PVT base which forms free radicals. This results in an additional absorptive component causing increased transmission loss and light yield loss with increasing dose.

  8. Energy resolution in semiconductor gamma radiation detectors using heterojunctions and methods of use and preparation thereof

    DOEpatents

    Nikolic, Rebecca J.; Conway, Adam M.; Nelson, Art J.; Payne, Stephen A.

    2012-09-04

    In one embodiment, a system comprises a semiconductor gamma detector material and a hole blocking layer adjacent the gamma detector material, the hole blocking layer resisting passage of holes therethrough. In another embodiment, a system comprises a semiconductor gamma detector material, and an electron blocking layer adjacent the gamma detector material, the electron blocking layer resisting passage of electrons therethrough, wherein the electron blocking layer comprises undoped HgCdTe. In another embodiment, a method comprises forming a hole blocking layer adjacent a semiconductor gamma detector material, the hole blocking layer resisting passage of holes therethrough. Additional systems and methods are also presented.

  9. Results from irradiation tests on D0 Run 2a silicon detectors at the Radiation Damage Facility at Fermilab

    SciTech Connect

    Gardner, J.; Cerber, C.; Ke, Z.; Korjanevsky, S.; Leflat, A.; Lehner, F.; Lipton, R.; Lackey, J.; Merkin, M.; Rapidis, P.; Rykalin, V.; Shabalina, E.; Spiegel, L.; Stutte, L.; Webber, B.; /Kansas U. /Kansas State U. /Illinois U., Chicago /Fermilab /Moscow State U. /Zurich U. /NICADD, DeKalb

    2006-03-01

    Several different spare modules of the D0 experiment Silicon Microstrip Tracker (SMT) have been irradiated at the Fermilab Booster Radiation Damage Facility (RDF). The total dose received was 2.1 MRads with a proton flux of {approx} 3 {center_dot} 10{sup 11} p/cm{sup 2} sec. The irradiation was carried out in steps of 0.3 or 0.6 MRad, with several days between the steps to allow for annealing and measurements. The leakage currents and depletion voltages of the devices increased with dose, as expected from bulk radiation damage. The double sided, double metal devices showed worse degradation than the less complex detectors.

  10. An evaluation of the Kearny Fallout Meter (KFM), a radiation detector constructed from commonly available household materials.

    PubMed

    McDonald, J T; West, W G; Kearfott, K J

    2004-11-01

    A radiation detector constructed of common household materials was developed at Oak Ridge National Laboratory (ORNL) by Cresson H. Kearny and has been referred to as the Kearny Fallout Meter (KFM). Developed during the height of the Cold War, the KFM was intended to place a radiation meter capable of measuring fallout from nuclear weapons in the hands of every U.S. citizen. Instructions for the construction of the meter, as well as information about radiation health effects, were developed in the form of multi-page newspaper insert. Subsequently, the sensitivity of the meter was refined by a high school teacher, Dr. Paul S. Lombardi, for use in demonstrations about radiation. The meter is currently being marketed for survivalists in light of potential radiation terrorist concerns. The KFM and Lombardi's variation of it are constructed and evaluated for this work. Calibrated tests of the response and variations in response are reported. A critique of the multi-page manual is made. In addition, the suitability of using such a detector, in terms of actual ease of construction and practical sensitivity, is discussed for its use in demonstrations and introductory classes on nuclear topics. PMID:15551780

  11. Modeling of the signal induced by an incident radiation in semi-insulating GaAs detectors

    SciTech Connect

    Cola, A.; Vasanelli, L.; Reggiani, L.

    1998-12-31

    The authors develop a Monte Carlo simulator of the charge signal induced by an external radiation on a semi-insulating GaAs detector. The role played by trapping and detrapping processes and the dynamics of generated carriers are investigated. The relative contribution to the charge signal of fast and slow time components as well as the time constant of the slow component are studied as a function of the applied voltage. Present findings provide a physical interpretation of available experimental results.

  12. High quantum efficiency megavoltage imaging with thick scintillator detectors for image guided radiation therapy

    NASA Astrophysics Data System (ADS)

    Gopal, Arun

    In image guided radiation therapy (IGRT), imaging devices serve as guidance systems to aid patient set-up and tumor volume localization. Traditionally, 2-D megavoltage x-ray imagers, referred to as electronic portal imaging devices (EPIDs), have been used for planar target localization, and have recently been extended to perform 3-D volumetric reconstruction via cone-beam computed tomography (CBCT). However, current EPIDs utilize thin and inefficient phosphor screen detectors and are subsequently limited by poor soft tissue visualization, which limits their use for CBCT. Therefore, the use of thick scintillation media as megavoltage x-ray detectors for greater x-ray sensitivity and enhanced image quality has recently been of significant interest. In this research, two candidates for thick scintillators: CsI(Tl) and terbium doped scintillation glass were investigated in separate imaging configurations. In the first configuration, a thick scintillation crystal (TSC) consisting of a thick, monolithic slab of CsI(Tl) was coupled to a mirror-lens-camera system. The second configuration is based on a fiber-optic scintillation glass array (FOSGA), wherein the scintillation glass is drawn into long fiber-optic conduits, inserted into a grid-type housing constructed out of polymer-tungsten alloy, and coupled to an array of photodiodes for digital read-out. The imaging prototypes were characterized using theoretical studies and imaging measurements to obtain fundamental metrics of imaging performance. Spatial resolution was measured based on a modulation transfer function (MTF), noise was evaluated in terms of a noise power spectrum (NPS), and overall contrast was characterized in the form of detective quantum efficiency (DQE). The imaging studies were used to optimize the TSC and FOSGA imagers and propose prototype configurations for order-of-magnitude improvements in overall image quality. In addition, a fast and simple technique was developed to measure the MTF, NPS, and DQE metrics for clinical EPID and CBCT systems based on a novel adaptation of a traditional line-pair resolution bar-pattern. This research provides two significant benefits to radiotherapy: the characterization of a new generation of thick scintillator based megavoltage x-ray imagers for CBCT based IGRT, and the novel adaptation of fundamental imaging metrics from imaging research to routine clinical performance monitoring.

  13. SU-E-T-390: Characterization of the PTW Synthetic Diamond Detector for Radiation Therapy Measurements

    SciTech Connect

    Stathakis, S; Markovic, M; Mavroidis, P; Papanikolaou, N

    2014-06-01

    Purpose: To investigate the dosimetric properties of new commercially available synthetic single crystal diamond detector under irradiation with therapeutic photon beams from linear accelerators. Methods: A single crystal diamond detector was tested using 6MV photon beam. The detector performance was evaluated for reproducibility, linearity with dose, dose rate dependence, angular dependence, collection efficiency, and measurement of output factors. Lateral field profiles, and percentage depth dose profiles were measured and compared against commercially available detectors. Results: Reproducibility of the detector measurement has a standard deviation of 0.1%. A good linear behavior of the detector response as a function of the delivered dose is observed with deviations below ±0.03% in the dose range from 0.1 to 5Gy. In addition, the detector response is dose rate independent, with deviations below 0.1% in the investigated dose rate range from 1 to 10Gy per min. Charge collection efficiency deviations were within 0.07% from 1 to 10Gy. No angular dependence along the radial direction while up to 1.3% angular dependence was observed in the axial direction. Percentage depth dose curves obtained from the diamond detector are in good agreement with the ones from the reference dosimeters. Lateral beam profile measurements show an overall good agreement among detectors, taking into account their respective geometrical features. The spatial resolution of solid state detectors is confirmed to be better than that of ionization chambers, being the one from the diamond detector comparable to that of the silicon diode. Conclusions: The observed dosimetric properties indicate that the tested diamond detector is a suitable candidate for clinical photon beam dosimetry. The agreement with reference dosimeters show that the detector is suitable for measurements for large fields as well as small fields as the ones used for stereotactic radiotherapy.

  14. 3D sensitive voxel detector of ionizing radiation based on Timepix device

    NASA Astrophysics Data System (ADS)

    Soukup, P.; Jakubek, J.; Vykydal, Z.

    2011-01-01

    Position sensitive detectors are evolving towards higher segmentation geometries from 0D (single pad) over 1D (strip) to 2D (pixel) detectors. Each step has brought up substantial expansion in the field of applications. The next logical step in this evolution is to design a 3D, i.e. voxel detector. The voxel detector can be constructed from 2D volume element detectors arranged in layers forming a 3D matrix of sensitive elements — voxels. Such detectors can effectively record tracks of energetic particles. By proper analysis of these tracks it is possible to determine the type, direction and energy of the primary particle. One of the prominent applications of such device is in the localization and identification of gamma and neutron sources in the environment. It can be also used for emission and transmission radiography in many fields where standard imagers are currently utilized. The qualitative properties of current imagers such as: spatial resolution, efficiency, directional sensitivity, energy sensitivity and selectivity (background suppression) can be improved. The first prototype of a voxel detector was built using a number of Timepix devices. Timepix is hybrid semiconductor detector consisting of a segmented semiconductor sensor bump-bonded to a readout chip. Each sensor contains 256x256 square pixels of 55 ?m size. The voxel detector prototype was successfully tested to prove the concept functionality. The detector has a modular architecture with a daisy chain connection of the individual detector layers. This permits easy rearrangement due to its modularity, while keeping a single readout system for a variable number of detector layers. A limitation of this approach is the relatively large inter-layer distance (4 mm) compared to the pixel thickness (0.3 mm). Therefore the next step in the design is to decrease the space between the 2D detectors.

  15. Position sensitive detectors for synchrotron radiation studies: the tortoise and the hare?

    NASA Astrophysics Data System (ADS)

    Lewis, Rob

    2003-11-01

    The huge gulf between the high photon fluxes available from synchrotrons and the capabilities of detectors to measure the resulting photon, electron or ion signals is well known. Whilst accelerator technology continues to advance at a rapid pace, it is detector performance which represents the limiting factor for many synchrotron experiments. In some cases there are still single channel counting detectors based on 40-year-old designs operational on synchrotron beamlines. The dream of many researchers is a detector which is able to simultaneously image and perform spectroscopy at the required data rates. A solution is the massive integration of parallel electronics into detectors on a pixel by pixel basis. These ideas have been in gestation for very many years awaiting sufficient funding, nevertheless, several prototypes are now at the testing stage. The current status of these and other detector developments targeted at synchrotron science are briefly reviewed.

  16. HST/WFC3: Understanding and Mitigating Radiation Damage Effects in the CCD Detectors

    NASA Astrophysics Data System (ADS)

    Baggett, S.; Anderson, J.; Sosey, M.; MacKenty, J.; Gosmeyer, C.; Noeske, K.; Gunning, H.; Bourque, M.

    2015-09-01

    At the heart of the Hubble Space Telescope Wide Field Camera 3 (HST/WFC3) UVIS channel resides a 4096x4096 pixel e2v CCD array. While these detectors are performing extremely well after more than 5 years in low-earth orbit, the cumulative effects of radiation damage cause a continual growth in the hot pixel population and a progressive loss in charge transfer efficiency (CTE) over time. The decline in CTE has two effects: (1) it reduces the detected source flux as the defects trap charge during readout and (2) it systematically shifts source centroids as the trapped charge is later released. The flux losses can be significant, particularly for faint sources in low background images. Several mitigation options exist, including target placement within the field of view, empirical stellar photometric corrections, post-flash mode and an empirical pixel-based CTE correction. The application of a post-flash has been remarkably effective in WFC3 at reducing CTE losses in low background images for a relatively small noise penalty. Currently all WFC3 observers are encouraged to post-flash images with low backgrounds. Another powerful option in mitigating CTE losses is the pixel-based CTE correction. Analagous to the CTE correction software currently in use in the HST Advanced Camera for Surveys (ACS) pipeline, the algorithm employs an empirical observationally-constrained model of how much charge is captured and released in order to reconstruct the image. Applied to images (with or without post-flash) after they are acquired, the software is currently available as a standalone routine. The correction will be incorporated into the standard WFC3 calibration pipeline.

  17. Properties of thin film radiation detectors and their application to dosimetry and quality assurance in x-ray imaging

    NASA Astrophysics Data System (ADS)

    Elshahat, Bassem

    The characteristics of two different types of thin-film radiation detectors are experimentally investigated: organic photovoltaic cells (OPV) and a new self-powered detector that operates based on high-energy secondary electrons (HEC). Although their working principles are substantially different, they both can be used for radiation detection and image formation in medical applications. OPVs with different active layer material thicknesses and aluminum electrode areas were fabricated. The OPV cell consisted of P3HT: PCBM photoactive materials, composed of donor and acceptor semiconducting organic materials, sandwiched between an aluminum electrode as anode and an indium tin oxide (ITO) electrode as a cathode. The detectors were exposed to 60150 kVp x rays, which generated photocurrent in the active layer. The electric charge production in the OPV cells was measured. The net current as function of beam energy (kVp) was proportional to ~1/kVp0.45 when adjusted for x-ray beam output. The best combination of parameters for these cells was 270-nm active layer thicknesses for 0.7cm-2 electrode area. The measured current ranged from about 0.7 to 2.4 nA/cm2 for 60-150 kVp, corresponding to about 0.09 -- 0.06 nA/cm2/mGy, respectively, when adjusted for the output x-ray source flux. The HEC detection concept was recently proposed and experimentally demonstrated by a UML/HMS research group. HEC detection employs direct conversion of high-energy electron current to detector signal without external power and amplification. The potential of using HEC detectors for diagnostic imaging application was investigated by using a heterogeneous phantom consisting of a water cylinder with Al and wax rod inserts.

  18. Clinical radiation therapy measurements with a new commercial synthetic single crystal diamond detector.

    PubMed

    Laub, Wolfram U; Crilly, Richard

    2014-01-01

    A commercial version of a synthetic single crystal diamond detector (SCDD) in a Schottky diode configuration was recently released as the new type 60019 microDiamond detector (PTW-Freiburg, Germany). In this study we investigate the dosimetric properties of this detector to independently confirm that findings from the developing group of the SCDDs still hold true for the commercial version of the SCDDs. We further explore if the use of the microDiamond detector can be expanded to high-energy photon beams of up to 15 MV and to large field measure- ments. Measurements were performed with an Elekta Synergy linear accelerator delivering 6, 10, and 15 MV X-rays, as well as 6, 9, 12, 15, and 20 MeV electron beams. The dependence of the microdiamond detector response on absorbed dose after connecting the detector was investigated. Furthermore, the dark current of the diamond detector was observed after irradiation. Results are compared to similar results from measurements with a diamond detector type 60003. Energy dependency was investigated, as well. Photon depth-dose curves were measured for field sizes 3 × 3, 10 × 10, and 30 × 30 cm2. PDDs were measured with the Semiflex type 31010 detector, microLion type 31018 detector, P Diode type 60016, SRS Diode type 60018, and the microDiamond type 60019 detector (all PTW-Freiburg). Photon profiles were measured at a depth of 10 cm. Electron depth-dose curves normalized to the dose maximum were measured with the 14 × 14 cm2 electron cone. PDDs were measured with a Markus chamber type 23343, an E Diode type 60017 and the microDiamond type 60019 detector (all PTW-Freiburg). Profiles were measured with the E Diode and microDiamond at half of D90, D90, D70, and D50 depths and for electron cone sizes of 6 × 6 cm2, 14 × 14 cm2, and 20 × 20 cm2. Within a tol- erance of 0.5% detector response of the investigated detector was stable without any preirradiation. After preirradition with approximately 250 cGy the detector response was stable within 0.1%. A dark current after irradiation was not observed. The microDiamond detector shows no energy dependence in high energy photon or electron dosimetry. Electron PDD measurements with the E Diode and micro- Diamond are in good agreement. However, compared to E Diode measurements, dose values in the bremsstrahlungs region are about 0.5% lower when measured with the microDiamond detector. Markus detector measurements agree with E Diode measurements in the bremsstrahlungs region. For depths larger than dmax, depth-dose curves of photon beams measured with the microDiamond detector are in close agreement to those measured with the microLion detector for small fields and with those measured with a Semiflex 0.125 cc ionization chamber for large fields. Differences are in the range of 0.25% and less. For profile measurements, microDiamond detector measurements agree well with microLion and P Diode measurements in the high-dose region of the profile and the penumbra region. For areas outside the open field, P Diode measurements are about 0.5%-1.0% higher than microDiamond and microLion measurements. Thus it becomes evident that the investigated diamond detector (type 60019) is suitable for a wide range of applications in high-energy photon and electron dosimetry and is interesting for relative, as well as absolute, dosimetry.  PMID:25493512

  19. Calibration of solid state nuclear track detectors at high energy ion beams for cosmic radiation measurements: HAMLET results

    NASA Astrophysics Data System (ADS)

    Szabó, J.; Pálfalvi, J. K.

    2012-12-01

    The MATROSHKA experiments and the related HAMLET project funded by the European Commission aimed to study the dose burden of the crew working on the International Space Station (ISS). During these experiments a human phantom equipped with several thousands of radiation detectors was exposed to cosmic rays inside and outside the ISS. Besides the measurements realized in Earth orbit, the HAMLET project included also a ground-based program of calibration and intercomparison of the different detectors applied by the participating groups using high-energy ion beams. The Space Dosimetry Group of the Centre for Energy Research (formerly Atomic Energy Research Institute) participated in these experiments with passive solid state nuclear track detectors (SSNTDs). The paper presents the results of the calibration experiments performed in the years 2008-2011 at the Heavy Ion Medical Accelerator (HIMAC) of the National Institute of Radiological Sciences (NIRS), Chiba, Japan. The data obtained serve as update and improvement for the previous calibration curves which are necessary for the evaluation of the SSNTDs exposed in unknown space radiation fields.

  20. Development of a novel radiation imaging detector system for in vivo gene imaging in small animal studies

    SciTech Connect

    Weisenberger, A.G.; Bradley, E.L.; Saha, M.S.; Majewski, S.

    1998-06-01

    The authors report preliminary results from a prototype of radiation imaging technology which takes advantage of the emission properties of the radioisotope iodine 125 ({sup 125}I) as the probe. The detector system utilizes crystal scintillators and a position sensitive photomultiplier tube. Iodine 125 decays via electron capture emitting a 35-keV gamma ray with the prompt emission of several 27-32-keV {Kappa} {alpha} and {Kappa} {beta} shell X rays. Because of this, a coincidence condition can be set to detect the {sup 125}I decay, thus reducing background radiation contribution to the image. The prototype detector the authors report has a limited sensitivity and detection area because of the size of the scintillators and photomultiplier tubes, yet it performed well enough to demonstrate the viability of this method for imaging {sup 125}I in a mouse. Mouse imaging studies of iodine uptake by the thyroid and melatonin binding have been done with this detector system using doses of {sup 125}I alone or attached to the melatonin. Many studies in molecular biology follow the expression and regulation of a gene at different stages of an organism`s development or under different physiological conditions. Molecular biology research could benefit from this detection system by utilizing {sup 125}I-labeled gene probes.

  1. Design of inexpensive diffraction limited focal plane arrays for millimeter wavelength and terahertz radiation using glow discharge detector pixels

    NASA Astrophysics Data System (ADS)

    Abramovich, A.; Kopeika, N. S.; Rozban, D.

    2008-08-01

    Development of focal plane arrays (FPAs) for millimeter wavelength and terahertz radiation is presented in this paper. FPA is based on an inexpensive glow discharge detector (GDD) that serves as a pixel in the FPA. It was shown in previous investigations [A. Abramovich et al., Appl. Opt. 46, 7207 (2007)] that those inexpensive neon indicator lamp GDDs are quite sensitive to millimeter wavelength and terahertz radiation. The diameter of the GDD lamp is 6 mm and thus the FPA can be diffraction limited. Development of a FPA using such devices as detectors is advantageous since the cost of such lamps is around 0.2-0.5 per lamp, and it also serves as a room temperature detector. Experimental results at 100 GHz show that the responsivity of the terahertz FPA 4×4 GDD pixel is three times better than in previous measurements of A. Abramovich et al. [Appl. Opt. 46, 7207 (2007)].The addition of a parabolic reflector improves the accuracy of the noise equivalent power measurement which was found to be 6×10-9 W/?Hz for a 1 kHz modulation. However, it is expected to be considerably less at higher modulation frequencies because of much reduced noise.

  2. Radiation hardness assessment of the charge-integrating hybrid pixel detector JUNGFRAU 1.0 for photon science.

    PubMed

    Jungmann-Smith, J H; Bergamaschi, A; Brückner, M; Cartier, S; Dinapoli, R; Greiffenberg, D; Jaggi, A; Maliakal, D; Mayilyan, D; Medjoubi, K; Mezza, D; Mozzanica, A; Ramilli, M; Ruder, Ch; Schädler, L; Schmitt, B; Shi, X; Tinti, G

    2015-12-01

    JUNGFRAU (adJUstiNg Gain detector FoR the Aramis User station) is a two-dimensional hybrid pixel detector for photon science applications in free electron lasers, particularly SwissFEL, and synchrotron light sources. JUNGFRAU is an automatic gain switching, charge-integrating detector which covers a dynamic range of more than 10(4) photons of an energy of 12 keV with a good linearity, uniformity of response, and spatial resolving power. The JUNGFRAU 1.0 application-specific integrated circuit (ASIC) features a 256 × 256 pixel matrix of 75 × 75 ?m(2) pixels and is bump-bonded to a 320 ?m thick Si sensor. Modules of 2 × 4 chips cover an area of about 4 × 8 cm(2). Readout rates in excess of 2 kHz enable linear count rate capabilities of 20 MHz (at 12 keV) and 50 MHz (at 5 keV). The tolerance of JUNGFRAU to radiation is a key issue to guarantee several years of operation at free electron lasers and synchrotrons. The radiation hardness of JUNGFRAU 1.0 is tested with synchrotron radiation up to 10 MGy of delivered dose. The effect of radiation-induced changes on the noise, baseline, gain, and gain switching is evaluated post-irradiation for both the ASIC and the hybridized assembly. The bare JUNGFRAU 1.0 chip can withstand doses as high as 10 MGy with minor changes to its noise and a reduction in the preamplifier gain. The hybridized assembly, in particular the sensor, is affected by the photon irradiation which mainly shows as an increase in the leakage current. Self-healing of the system is investigated during a period of 11 weeks after the delivery of the radiation dose. Annealing radiation-induced changes by bake-out at 100?°C is investigated. It is concluded that the JUNGFRAU 1.0 pixel is sufficiently radiation-hard for its envisioned applications at SwissFEL and synchrotron beam lines. PMID:26724009

  3. Review Article: Physics and Monte Carlo Techniques as Relevant to Cryogenic, Phonon and Ionization Readout of CDMS Radiation-Detectors

    E-print Network

    S. W. Leman

    2012-06-26

    This review discusses detector physics and Monte Carlo techniques for cryogenic, radiation detectors that utilize combined phonon and ionization readout. A general review of cryogenic phonon and charge transport is provided along with specific details of the Cryogenic Dark Matter Search detector instrumentation. In particular this review covers quasidiffusive phonon transport, which includes phonon focusing, anharmonic decay and isotope scattering. The interaction of phonons in the detector surface is discussed along with the downconversion of phonons in superconducting films. The charge transport physics include a mass tensor which results from the crystal band structure and is modeled with a Herring Vogt transformation. Charge scattering processes involve the creation of Neganov-Luke phonons. Transition-edge-sensor (TES) simulations include a full electric circuit description and all thermal processes including Joule heating, cooling to the substrate and thermal diffusion within the TES, the latter of which is necessary to model normal-superconducting phase separation. Relevant numerical constants are provided for these physical processes in germanium, silicon, aluminum and tungsten. Random number sampling methods including inverse cumulative distribution function (CDF) and rejection techniques are reviewed. To improve the efficiency of charge transport modeling, an additional second order inverse CDF method is developed here along with an efficient barycentric coordinate sampling method of electric fields. Results are provided in a manner that is convenient for use in Monte Carlo and references are provided for validation of these models.

  4. Analysis of the pulse shapes obtained from single crystal Cd 0.9Zn 0.1Te radiation detectors

    NASA Astrophysics Data System (ADS)

    Hess, R.; DeAntonis, P.; Morton, E. J.; Gilboy, W. B.

    1994-12-01

    Over the past thirty years there has been considerable research into the properties of CdTe semiconductor radiation detectors. Recently, the quality of CdTe detectors has improved (notably by the substitution of around 10% of the cadmium by zinc) to the point where high quality room temperature gamma-ray spectroscopy is possible using devices of volume 1 cm 3 or greater. We are currently investigating the variation in pulse shape resulting from ?-ray interactions in CdZnTe detectors supplied by eV Products. The impact of these variations is assessed in terms of its effect on the resolution in the pulse height spectrum. Parameters studied for individual pulses include the shaping amplifier amplitude and slew rate of the preamplifier output pulse. These signals are digitised using an oscilloscope controlled by a PC using IEEE-488 data transfers. Three-dimensional plots of this data are used to observe the distribution of detector outputs. Results are shown for 3 mm × 3 mm × 2 mm thick Cd 0.9Zn 0.1. Te crystals which indicate that significant improvement in peak to background ratio can be obtained by selective histogramming of the main amplifier output pulses.

  5. Processing and characterization of edgeless radiation detectors for large area detection

    NASA Astrophysics Data System (ADS)

    Kalliopuska, J.; Wu, X.; Jakubek, J.; Eränen, S.; Virolainen, T.

    2013-12-01

    The edgeless or active edge silicon pixel detectors have been gaining a lot of interest due to improved silicon processing capabilities. At VTT, we have recently triggered a multi-project wafer process of edgeless silicon detectors. Totally 80 pieces of 150 mm wafers were processed to provide a given number of detector variations. Fabricated detector thicknesses were 100, 200, 300 and 500 ?m. The polarities of the fabricated detectors on the given thicknesses were n-in-n, p-in-n, n-in-p and p-in-p. On the n-in-n and n-in-p wafers the pixel isolation was made either with a common p-stop grid or with a shallow p-spray doping. The wafer materials were high resistivity Float Zone and Magnetic Czochralski silicon with crystal orientation of <100>. In this paper, the electric properties on various types of detectors are presented. The results from spectroscopic measurement show a good energy resolution of the edge pixels, indicating an excellent charge collection near the edge pixels of the edgeless detector.

  6. Investigation of Charge Transport Properties of CdZnTe Detectors with Synchrotron X-ray Radiation

    SciTech Connect

    Yang,G.; Bolotnikov, A.E.; Camarda, G.S.; Cui, Y.; Hossain, A.; James, R.B.

    2008-10-19

    Various internal defects, such as Te inclusions, twin boundaries, dislocation, etc., are prevalent in as-grown CdZnTe (CZT) crystals, which affect the charge transport properties of CZT crystals and, therefore, worsen the performance of CZT detectors. In order to develop high quality CZT detectors, it is imperative to clarify the effects of internal defects on the charge transport properties of CZT. Simple flood illumination with nuclear radiation source cannot reveal the nature of highly localized defects in CZT. Therefore, at Brookhaven's National Synchrotron Light Source (NSLS), we have developed a unique testing system for micro-scale defect investigation of CZT, which employs an X-ray beam collimated with the spatial resolution as small as 3 x 3 {micro}m{sup 2}, a microscopic size comparable to the scale of common defects in CZT. This powerful tool enables us to investigate the effect of internal defects on charge transport properties of CZT in detail.

  7. Cross-calibration of the transition radiation detector of AMS-02 for an energy measurement of cosmic-ray ions

    NASA Astrophysics Data System (ADS)

    Obermeier, A.; Korsmeier, M.

    2015-01-01

    Since May 2011 the AMS-02 experiment is installed on the International Space Station and is observing cosmic radiation. It consists of several state-of-the-art sub-detectors, which redundantly measure charge and energy of traversing particles. Due to the long exposure time of AMS-02 of many years the measurement of momentum for protons and ions is limited systematically by the spatial resolution and magnetic field strength of the silicon tracker. The maximum detectable rigidity for protons is about 1.8 TV, for helium about 3.6 TV. We investigate the possibility to extend the range of the energy measurement for heavy nuclei (Z ? 2) with the transition radiation detector (TRD). The response function of the TRD shows a steep increase in signal from the level of ionization at a Lorentz factor ? of about 500 to ? ? 20, 000 , where the transition radiation signal saturates. For heavy ions the signal fluctuations in the TRD are sufficiently small to allow an energy measurement with the TRD beyond the limitations of the tracker. The energy resolution of the TRD is determined and reaches a level of about 20% for boron (Z = 5). After adjusting the operational parameters of the TRD a measurement of boron and carbon could be possible up to 5 TeV/nucleon.

  8. Power monitoring in space nuclear reactors using silicon carbide radiation detectors

    NASA Technical Reports Server (NTRS)

    Ruddy, Frank H.; Patel, Jagdish U.; Williams, John G.

    2005-01-01

    Space reactor power monitors based on silicon carbide (SiC) semiconductor neutron detectors are proposed. Detection of fast leakage neutrons using SiC detectors in ex-core locations could be used to determine reactor power: Neutron fluxes, gamma-ray dose rates and ambient temperatures have been calculated as a function of distance from the reactor core, and the feasibility of power monitoring with SiC detectors has been evaluated at several ex-core locations. Arrays of SiC diodes can be configured to provide the required count rates to monitor reactor power from startup to full power Due to their resistance to temperature and the effects of neutron and gamma-ray exposure, SiC detectors can be expected to provide power monitoring information for the fill mission of a space reactor.

  9. Gamma radiation induced background determination for (n,?) measurements with 4? detectors.

    SciTech Connect

    Reifarth, R.; Browne, J. C.; Esch, E. I.; Haight, R. C.; O'Donnell, J. M.; Kronenberg, A.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M.

    2003-07-29

    The main focus of this report is to investigate possibilities to disentangle the target originating ?- background from background caused by scattered neutrons at the sample assuming a DANCE like detector to measure detect the capture events.

  10. LRAD, semiconductor, and other radiation detectors applied to environmental monitoring for alpha and beta contamination

    SciTech Connect

    MacArthur, D.W.; Bower, K.E.

    1993-08-01

    The very short range of alpha particles in air (typically 2 to 3 cm) has severely limited the utility of traditional alpha monitors for detecting and identifying small amounts of alpha-producing contamination in soil, water, and other materials. Monitors based on the traditional alpha detector technology are often hard-pressed to meet continually increasing sensitivity requirements. The long-range alpha detector (LRAD) avoids the distance restriction by detecting the ions produced by the interaction of alpha particles with air, rather than the alpha particles directly. The ions are swept into an ion detector either by a moving air current (generated by a fan) or a weak electric field. The LRAD is limited by the distance the ions can travel in the {approximately}5-s ion lifetime (1 to 100 m), rather than by the several-centimeter range of the alpha particles. The LRAD can be used to perform sensitive (less than 10 disintegrations per minute per 100 cm{sup 2}) field scans of large surface areas (ranging from hundreds of square meters of concrete floor to thousands of square meters of soil). Since the ``active`` element in a LRAD is a solid-metal ion collection plate, the detector is relatively inexpensive, easy to service, and quite rugged. However, the LRAD cannot supply any spectroscopic information to help identify the contaminant. Semiconductor, ionization chamber, and other types of particle detector can generate clean spectra from small samples of material and identify trace amounts of surface contamination. These detectors are rugged enough to use routinely in a mobile laboratory for isotope identification of ``hot spots`` located by the LRAD system. This detector combination has applications to field beta-particle monitoring (such as would result from tritium contamination) as well as alpha particle detection.

  11. On the possibility to use semiconductive hybrid pixel detectors for study of radiation belt of the Earth

    E-print Network

    Guskov, A; Smolyanskiy, P; Zhemchugov, A

    2015-01-01

    The scientific apparatus "Gamma-400" designed for study of hadron and electromagnetic components of cosmic rays will be launched to an elliptic orbit with the apogee of about 300 000 km and the perigee of about 500 km. Such a configuration of the orbit allows it to cross periodically the radiation belt and the outer part of magnetosphere. We discuss the possibility to use hybrid pixel detecters based on the Timepix chip and semiconductive sensors on board the "Gamma-400" apparatus. Due to high granularity of the sensor (pixel size is 55 $mu$m) and possibility to measure independently an energy deposition in each pixel, such compact and lightweight detector could be a unique instrument for study of spatial, energy and time structure of electron and proton components of the radiation belt.

  12. Simulated and associated experimental results of CdZnTe radiation detector response for gamma-ray imaging applications

    SciTech Connect

    Verger, L.; Bonnefoy, J.P.; Gliere, A.; Ouvrier-Buffet, P.; Rosaz, M.

    1998-12-31

    Simulated and associated experimental results of a high efficiency CdZnTe (CZT) radiation detector response for gamma-ray imaging applications are presented. The model of a high efficiency semiconductor gamma ray detector takes into account several different physical phenomena involved in the detection and correction processes, namely the geometry of the irradiation, the gamma-ray`s interaction with the crystal, the physics of the semiconductor`s charge collection, the electric field distribution and the pulse height correction method. A few important decoupling assumptions allow the authors to use a one dimensional charge collection simulation with a two-dimensional field model and a full three dimensional Monte-Carlo calculation of the gamma ray interactions. The model allows calculation of charge collection and gamma ray spectra for non uniform electric field distribution in either planar, striped or pixellated detector. The model takes also into account the new CZT fast pulse correction method and its associated noise by considering the pulse height and the rise time of electron signals (Bi-Parametric spectrum) for all gamma ray interactions. Specific simulated and experimental spectra at 122 keV are presented for CZT. First, basic spectral changes are calculated for variations in crystal and detector properties like mobility, trapping lifetime and electric field profiles. Second, new experimental results of the fast pulse correction method applied to different CZT detector grades are presented. This method allows to achieve a high detection efficiency (> 80%) with a good energy resolution (< 6% FWHM) at 122 keV for a 4 x 4 x 6 mm{sup 3} CZT detector. No specific contact geometry is needed and the unusual low applied bias voltage allows to limit the aging and break voltage effects and also the dark current and its associated noise. This fast correction method is expected to be useful for medical imaging and other applications. Finally, simulated Bi-Parametric (BP) spectra expected with the fast pulse correction method according to the detector properties (electric field profiles, electron lifetime) are simulated and a qualitative comparison is provided.

  13. Pulse-shape analysis for gamma background rejection in thermal neutron radiation using CVD diamond detectors

    NASA Astrophysics Data System (ADS)

    Kavrigin, P.; Finocchiaro, P.; Griesmayer, E.; Jericha, E.; Pappalardo, A.; Weiss, C.

    2015-09-01

    A novel technique for the rejection of gamma background from charged-particle spectra was demonstrated using a CVD diamond detector with a 6Li neutron converter installed at a thermal neutron beamline of the TRIGA research reactor at the Atominstitut (Vienna University of Technology). Spectra of the alpha particles and tritons of 6Li(n,T)4He thermal neutron capture reaction were separated from the gamma background by a new algorithm based on pulse-shape analysis. The thermal neutron capture in 6Li is already used for neutron flux monitoring, but the ability to remove gamma background allows using a CVD diamond detector for thermal neutron counting. The pulse-shape analysis can equally be applied to all cases where the charged products of an interaction are absorbed in the diamond and to other background particles that fully traverse the detector.

  14. Resonant nuclear scattering of synchrotron radiation: Detector development and specular scattering from a thin layer of {sup 57}Fe

    SciTech Connect

    Baron, A.Q.R.

    1995-04-01

    This thesis explores resonant nudear scattering of synchrotron radiation. An introductory chapter describes some useful concepts, such as speedup and coherent enhancement, in the context of some basic physical principles. Methods of producing highly monochromatic synchrotron beams usmg either electronic or nuclear scattering are also discussed. The body of the thesis concentrates on detector development and specular scattering from iynthetic layered materials. A detector employing n-dcrochannel plate electron multipliers is shown to have good ({approximately}50%) effidency for detecting 14.4 key x-rays incident at small ({approximately}0.5 degree) grazing angles onto Au or CsI photocathodes. However, being complicated to use, it was replaced with a large area (>=lan2) avalanche photodiode (APD) detector. The APD`s are simpler to use and have comparable (30--70%) efficiencies at 14.4 key, subnanosecond time resolution, large dynan-dc range (usable at rates up to {approximately}10{sup 8} photons/second) and low (<{approximately}0.01 cts/sec) background rates. Maxwell`s equations are used to derive the specular x-ray reflectivity of layered materials with resonant transitions and complex polarization dependencies. The effects of interfadal roughness are treated with some care, and the distorted wave Born approximation (DWBA) used to describe electronic scattering is generalized to the nuclear case. The implications of the theory are discussed in the context of grazing incidence measurements with emphasis on the kinematic and dynamical aspects of the scattering.

  15. Novel mm-wave and THz radiation active imaging system based on glow discharge detector (GDD) pixel

    NASA Astrophysics Data System (ADS)

    Kopeika, N. S.; Abramovich, A.; Rozban, D.

    2008-10-01

    A novel imaging system for mm wavelength and THz radiation is presented in this paper. The imaging system is based upon an inexpensive neon indicator lamp or glow discharge detector (GDD) that serves as a pixel in a focal plane array (FPA). It was shown in previous investigations that inexpensive neon indicator lamp GDDs are quite sensitive to mm wavelength and THz radiation. The diameter of the GDD lamp is 6 mm and thus the FPA can be diffraction limited. Using such neon lamps we realize a 4X4 FPA. We used a Polyethylene lens to focus the radiation on the FPA. First imaging results of the novel mm-wave and THz imaging system are presented here. They images are of decent quality. Increasing the resolution of the FPA to 8X8 or 16X16 will improve significantly the quality of the photos in the mm-wave and THz radiation. Our goal is to construct a 128X128 imaging system using the GDD technology.

  16. Development of pixelated mercuric iodide radiation detectors for room temperature gamma-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Baciak, James E.

    Mercuric iodide (HgI2) detectors were studied as potential gamma-ray spectrometers that can operate at room temperature or above without the need for cooling. Similar to other compound semiconductor materials, HgI 2 suffers from poor hole molibity and severe hole trapping. Thus, poor spectroscopic results will occur if this detector material used with conventional planar electrodes. The use of single polarity charge sensing, whereby the energy deposited by the gamma-ray is determined solely by electron movement and collection, was attempted by incorporating pixelated anodes. The results showed remarkable spectroscopic improvement over conventional electrodes, with less than 2% energy resolution from single pixels on a 1 cm thick detector using a 662 keV Cs-137 gamma-ray source. The conventional planar cathode showed no photopeak due to the lack of hole movement in HgI2. Since the cathode signal has a relatively linear dependence on the depth of interaction, both the anode pixel and cathode signals were used to measure the depth of interaction. This was then used to correct for electron trapping and variations of the induced charge with the depth of interaction. Depth correction further improved the resolution for single pixels to as low as 1.4% (˜9 keV) energy resolution. Nearly three-quarters of all pixels tested on 1 cm thick detectors had resolutions less than 2% after depth correction was performed. Pixelated HgI2 detectors were also used to study the charge transport properties of the material. While the measured hole transportation properties were similar to previously measured values, measured (mutau)e values were on the order of 10-3 cm2/V, about an order of magnitude better than previously measured values. This demonstrates that the material quality may have improved over the past several years. The pixelated HgI2 detectors showed very little polarization, and remained stable over several months of operation. Continued development of these detectors will allow them to compete with current CdZnTe detectors, possibly improving on detection efficiency due to the higher atomic number of HgI2.

  17. Laser-processed three dimensional graphitic electrodes for diamond radiation detectors

    SciTech Connect

    Caylar, Beno?-carett; Pomorski, Michal; Bergonzo, Philippe

    2013-07-22

    We have used an original approach for diamond detectors where three dimensional buried graphitic electrodes are processed in the bulk of a diamond substrate via laser-induced graphitization. Prototype made of polycrystalline chemical vapor deposition diamond was fabricated using a nanosecond UV laser. Its charge collection efficiency was evaluated using ?-particles emitted by a 241-Americium source. An improved charge collection efficiency was measured proving that laser micro-machining of diamond is a valid option for the future fabrication of three dimensional diamond detectors.

  18. Nanostructured LaF{sub 3}:Ce Quantum Dot Nuclear Radiation Detector

    SciTech Connect

    Guss, P., Guise, R., Reed, M., Mukhopadhyay, S., Yuan, D.

    2010-11-01

    Many radioactive isotopes have low energy X-rays and high energy gamma rays of interest for detection. The goal of the work presented was to demonstrate the possibility of measuring both low-energy X-rays and relatively high-energy gamma rays simultaneously using the nano-structured lanthanum bromide, lanthanum fluoride, or cerium bromide. The key accomplishments of the project was the building and acquisition of the LaF3:Ce nanocomposite detectors. Nanocomposite detectors are sensitive to {gamma}’s as well as n’s and X-rays.

  19. Laser-processed three dimensional graphitic electrodes for diamond radiation detectors

    NASA Astrophysics Data System (ADS)

    Caylar, Benoît; Pomorski, Michal; Bergonzo, Philippe

    2013-07-01

    We have used an original approach for diamond detectors where three dimensional buried graphitic electrodes are processed in the bulk of a diamond substrate via laser-induced graphitization. Prototype made of polycrystalline chemical vapor deposition diamond was fabricated using a nanosecond UV laser. Its charge collection efficiency was evaluated using ?-particles emitted by a 241-Americium source. An improved charge collection efficiency was measured proving that laser micro-machining of diamond is a valid option for the future fabrication of three dimensional diamond detectors.

  20. Laboratory simulation of cosmic radiation effects on stressed Ge:Ga detectors at L2 and curing

    NASA Astrophysics Data System (ADS)

    Stegmaier, Jutta M.; Birkmann, Stephan M.; Grözinger, Ulrich; Katterloher, Reinhard; Krause, Oliver; Lemke, Dietrich

    2006-06-01

    The Photodetector Array Camera and Spectrometer (PACS) is one of three science instruments on board the Herschel space observatory to be launched in 2008. It will perform imaging photometry and spectroscopy in the wavelength range from 57 ?m to 210 ?m. The integral field spectrometer contains two 25 x 16 pixel cameras of Gallium doped Germanium crystals (Ge:Ga). By stressing these crystals, cutoff wavelengths of 127 ?m (low-stressed, 200 N) and 205 ?m (high-stressed, 800 N) are reached. The characterization of these detectors (responsivity, noise equivalent power (NEP), dark current,...) is carried out at the Max-Planck-Institutes for Astronomy (MPIA, Heidelberg) and Extraterrestrial Physics (MPE, Garching). Both test facilities allow simulation of the in-flight operational conditions of the arrays and provide accurate IR fluxes by means of external/internal black bodies and calibrated cold attenuation filters. A radioactive 137Cs source is used at MPIA to simulate the steady cosmic radiation impact on the photoconductor arrays in order to study the radiation induced changes in responsivity, noise, and the transient behavior. The goal is to determine the optimal operating parameters (temperature, bias, integration time,..) for the operation at the L2 orbit, the best curing method, curing frequency and calibration procedure for high photometric accuracy. The "lessons learned" on operating, curing, deglitching and calibrating stressed Ge:Ga detectors during the ISO mission are applied as well as the relevant reports from IRAS and Spitzer.

  1. Radiation hardness investigation of avalanche photodiodes for the Projectile Spectator Detector readout at the Compressed Baryonic Matter experiment

    NASA Astrophysics Data System (ADS)

    Kushpil, Vasilij; Mikhaylov, Vasily; Kushpil, Svetlana; Tlustý, Pavel; Svoboda, Ondrej; Kugler, Andrej

    2015-07-01

    In this paper, we discuss results of avalanche photodiodes radiation tests for Projectile Spectator Detector at future Compressed Baryonic Matter experiment. The tests were carried out in Nuclear Physics Institute of ASCR in ?ež using the cyclotron facility. Secondary neutron beam was used for irradiation because the main radiation damage in the Projectile Spectator Detector is caused by neutrons. Two types of the avalanche photodiodes from Zecotek and Ketek manufacturers were investigated. Special attention was given to the noise investigation and self-annealing after the irradiation. We have irradiated two Ketek PM3375 diodes with equivalent dose for 1 MeV neutrons equal to 2.5±0.2×1012 n/cm2, and single Zecotek MAPD-3N diode with equivalent dose for 1 MeV neutrons equal to 3.4±0.2×1012 n/cm2. All the types of the diodes have shown an increasing level of the noise after the irradiation. From that we can conclude that those avalanche photodiodes are not able to detect single photons anymore due to high noise levels.

  2. Development of high pressure-high vacuum-high conductance piston valve for gas-filled radiation detectors

    NASA Astrophysics Data System (ADS)

    Prasad, D. N.; Ayyappan, R.; Kamble, L. P.; Singh, J. P.; Muralikrishna, L. V.; Alex, M.; Balagi, V.; Mukhopadhyay, P. K.

    2008-05-01

    Gas-filled radiation detectors need gas filling at pressures that range from few cms of mercury to as high as 25kg/cm2 at room temperature. Before gas-filling these detectors require evacuation to a vacuum of the order of ~1 × 10-5 mbar. For these operations of evacuation and gas filling a system consisting of a vacuum pump with a high vacuum gauge, gas cylinder with a pressure gauge and a valve is used. The valve has to meet the three requirements of compatibility with high-pressure and high vacuum and high conductance. A piston valve suitable for the evacuation and gas filling of radiation detectors has been designed and fabricated to meet the above requirements. The stainless steel body (80mm×160mm overall dimensions) valve with a piston arrangement has a 1/2 inch inlet/outlet opening, neoprene/viton O-ring at piston face & diameter for sealing and a knob for opening and closing the valve. The piston movement mechanism is designed to have minimum wear of sealing O-rings. The valve has been hydrostatic pressure tested up to 75bars and has Helium leak rate of less than 9.6×10-9 m bar ltr/sec in vacuum mode and 2×10-7 mbar ltr/sec in pressure mode. As compared to a commercial diaphragm valve, which needed 3 hours to evacuate a 7 litre chamber to 2.5×10-5 mbar, the new valve achieved vacuum 7.4×10-6mbar in the same time under the same conditions.

  3. Ionizing radiation detectors based on Ge-doped optical fibers inserted in resonant cavities.

    PubMed

    Avino, Saverio; D'Avino, Vittoria; Giorgini, Antonio; Pacelli, Roberto; Liuzzi, Raffaele; Cella, Laura; De Natale, Paolo; Gagliardi, Gianluca

    2015-01-01

    The measurement of ionizing radiation (IR) is a crucial issue in different areas of interest, from environmental safety and industrial monitoring to aerospace and medicine. Optical fiber sensors have recently proven good candidates as radiation dosimeters. Here we investigate the effect of IR on germanosilicate optical fibers. A piece of Ge-doped fiber enclosed between two fiber Bragg gratings (FBGs) is irradiated with gamma radiation generated by a 6 MV medical linear accelerator. With respect to other FBG-based IR dosimeters, here the sensor is only the bare fiber without any special internal structure. A near infrared laser is frequency locked to the cavity modes for high resolution measurement of radiation induced effects on the fiber optical parameters. In particular, we observe a variation of the fiber thermo-optic response with the radiation dose delivered, as expected from the interaction with Ge defect centers, and demonstrate a detection limit of 360 mGy. This method can have an impact in those contexts where low radiation doses have to be measured both in small volumes or over large areas, such as radiation therapy and radiation protection, while bare optical fibers are cheap and disposable. PMID:25686311

  4. Ionizing Radiation Detectors Based on Ge-Doped Optical Fibers Inserted in Resonant Cavities

    PubMed Central

    Avino, Saverio; D’Avino, Vittoria; Giorgini, Antonio; Pacelli, Roberto; Liuzzi, Raffaele; Cella, Laura; De Natale, Paolo; Gagliardi, Gianluca

    2015-01-01

    The measurement of ionizing radiation (IR) is a crucial issue in different areas of interest, from environmental safety and industrial monitoring to aerospace and medicine. Optical fiber sensors have recently proven good candidates as radiation dosimeters. Here we investigate the effect of IR on germanosilicate optical fibers. A piece of Ge-doped fiber enclosed between two fiber Bragg gratings (FBGs) is irradiated with gamma radiation generated by a 6 MV medical linear accelerator. With respect to other FBG-based IR dosimeters, here the sensor is only the bare fiber without any special internal structure. A near infrared laser is frequency locked to the cavity modes for high resolution measurement of radiation induced effects on the fiber optical parameters. In particular, we observe a variation of the fiber thermo-optic response with the radiation dose delivered, as expected from the interaction with Ge defect centers, and demonstrate a detection limit of 360 mGy. This method can have an impact in those contexts where low radiation doses have to be measured both in small volumes or over large areas, such as radiation therapy and radiation protection, while bare optical fibers are cheap and disposable. PMID:25686311

  5. Tests of the radiation hardness of VLSI Integrated Circuits and Silicon Strip Detectors for the SSC (Superconducting Super Collider) under neutron, proton, and gamma irradiation

    SciTech Connect

    Ziock, H.J.; Milner, C.; Sommer, W.F. ); Carteglia, N.; DeWitt, J.; Dorfan, D.; Hubbard, B.; Leslie, J.; O'Shaughnessy, K.F.; Pitzl, D.; Rowe, W.A.; Sadrozinski, H.F.W.; Seiden, A.; Spencer, E. . Inst. for Particle Physics); Ellison, J.A. ); Ferguson, P. ); Giubellino

    1990-01-01

    As part of a program to develop a silicon strip central tracking detector system for the Superconducting Super Collider (SSC) we are studying the effects of radiation damage in silicon detectors and their associated front-end readout electronics. We report on the results of neutron and proton irradiations at the Los Alamos National Laboratory (LANL) and {gamma}-ray irradiations at UC Santa Cruz (UCSC). Individual components on single-sided AC-coupled silicon strip detectors and on test structures were tested. Circuits fabricated in a radiation hard CMOS process and individual transistors fabricated using dielectric isolation bipolar technology were also studied. Results indicate that a silicon strip tracking detector system should have a lifetime of at least one decade at the SSC. 17 refs., 17 figs.

  6. RADIATION-HARD ASICS FOR OPTICAL DATA TRANSMISSION IN THE ATLAS PIXEL DETECTOR

    E-print Network

    Gan, K. K.

    driver controls the current flow from the positive power supply into the anode of the VCSEL-hard ASICs for optical data transmission in the ATLAS pixel detector at the LHC at CERN: a driver chip by the VCSEL Driver Chip (VDC) into a single-ended signal appropriate to drive a VCSEL. The optical signal from

  7. Scintillating plastic optical fiber radiation detectors in high energy particle physics

    SciTech Connect

    Bross, A.D.

    1991-10-26

    We describe the application of scintillating optical fiber in instrumentation for high energy particle physics. The basic physics of the scintillation process in polymers is discussed first and then we outline the fundamentals of scintillating fiber technology. Fiber performance, optimization, and characterization measurements are given. Detector applications in the areas of particle tracking and particle energy determination are then described. 13 refs., 12 figs.

  8. Radiation Hard Hybrid Pixel Detectors, and a bbbar Cross Section Measurement at the CMS Experiment

    E-print Network

    Sibille, Jennifer Ann

    2013-05-31

    . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 10 Side cutaway view of CASTOR showing the EM and HAD sections. . . 16 11 Side cutaway view of the ZDC showing the EM and HAD sections. . . . 17 12 The geometrical layout of one quadrant of the CMS pixel detector, show- ing the locations...

  9. The PAMELA Transition Radiation Detector F.S. Cafagna for the PAMELA Collaboration

    E-print Network

    Morselli, Aldo

    is the study of antiparticles in cosmic rays. The TRD detector was developed to provide particle identification performances will be presented. 1 Introduction Investigation of antiparticle spectra for energies larger than the correct calculation of the antiparticle produced in the atmosphere overburden and the exposure factor

  10. Development of a 144-channel Hybrid Avalanche Photo-Detector for Belle II ring-imaging Cherenkov counter with an aerogel radiator

    NASA Astrophysics Data System (ADS)

    Nishida, S.; Adachi, I.; Hamada, N.; Hara, K.; Iijima, T.; Iwata, S.; Kakuno, H.; Kawai, H.; Korpar, S.; Kriz^an, P.; Ogawa, S.; Pestotnik, R.; ?antelj, L.; Seljak, A.; Sumiyoshi, T.; Tabata, M.; Tahirovic, E.; Yoshida, K.; Yusa, Y.

    2015-07-01

    The Belle II detector, a follow up of the very successful Belle experiment, is under construction at the SuperKEKB electron-positron collider at KEK in Japan. For the PID system in the forward region of the spectrometer, a proximity-focusing ring-imaging Cherenkov counter with an aerogel radiator is being developed. For the position sensitive photon sensor, a 144-channel Hybrid Avalanche Photo-Detector has been developed with Hamamatsu Photonics K.K. In this report, we describe the specification of the Hybrid Avalanche Photo-Detector and the status of the mass production.

  11. Mechanism of Radiation Coupling to Plasma Wave Field Effect Transistor Sub-THz Detectors

    NASA Astrophysics Data System (ADS)

    Sakowicz, M.; ?usakowski, J.; Karpierz, K.; Grynberg, M.; Gwarek, W.; Knap, W.; Boubanga, S.

    2008-11-01

    Detection of 100 GHz and 285 GHz electromagnetic radiation by GaAs/AlGaAs field effect transistors with the gate length of 150 nm was investigated at 300 K as a function of the angle ? between the direction of linear polarization of the radiation and the symmetry axis of the field effect transistors. The angular dependence of the detected signal was found to be Acos2(?-?0)+C. A response of the transistor chip (including bonding wires and the substrate) to the radiation was numerically simulated. Calculations confirmed experimentally observed dependences and allowed to investigate the role of bonding wires and contact pads in coupling of the radiation to the transistor channel.

  12. Multipurpose Radiation Resistant Semiconductor Detectors for Alpha, Neutron & Low Energy Gamma Ray Measurements at High Temperatures in High-Intensity Gamma Ray

    SciTech Connect

    Ruddy, Frank H.

    2005-06-01

    Work scheduled under year two of DOE Grant DE-FG02-04ER63734 is on schedule and all year-two milestones have or will be met. Results to date demonstrate that unprecedented silicon carbide (SiC) energy resolution has been obtained, and that SiC detectors may achieve energy resolution that exceeds that obtainable with the best silicon alpha spectrometers. Fast-neutron energy spectrometry measurements indicate that recoil-ion energy spectrometry should be possible with SiC detectors. Furthermore, SiC detectors have been demonstrated to perform well even after gamma-ray exposures of 1.E09 Rad. This result and the previously demonstrated capability of SiC detectors to operate in elevated-temperature environments are very promising for potential DOE EMSP applications. A new class of multipurpose, radiation-resistant semiconductor detectors that can be used in elevated-temperature and high-radiation environments is being developed under this grant. These detectors, based on silicon carbide (SiC) semiconductor are designed to have larger active volumes than previously available SiC detectors, and are being tested for their response to alpha particles, X-rays and low energy gamma rays, and fast neutrons.

  13. A Radiation-Hard Silicon Drift Detector Array for Extraterrestrial Element Mapping

    NASA Technical Reports Server (NTRS)

    Gaskin, Jessica; Chen, Wei; De Geronimo, Gianluigi; Keister, Jeff; Li, Shaouri; Li, Zhen; Siddons, David P.; Smith, Graham

    2011-01-01

    Measurement of x-rays from the surface of objects can tell us about the chemical composition Absorption of radiation causes characteristic fluorescence from material being irradiated. By measuring the spectrum of the radiation and identifying lines in the spectrum, the emitting element (s) can be identified. This technique works for any object that has no absorbing atmosphere and significant surface irradiation : Our Moon, the icy moons of Jupiter, the moons of Mars, the planet Mercury, Asteroids and Comets

  14. Proposal for the award of a contract, without competitive tendering, for the supply of radiation hard luminosity detectors for the LHC

    E-print Network

    2006-01-01

    This document concerns the award of a contract, without competitive tendering, for the supply of four radiation-hard luminosity detectors for the LHC. For the reasons explained in this document, the Finance Committee is invited to agree to the negotiation of a contract with CEA-LETI (FR) for the supply of four radiation-hard luminosity detectors for a total amount of 247 770 euros (385 456 Swiss francs), not subject to revision. The amount in Swiss francs has been calculated using the present rate of exchange.

  15. GEM detector development for tokamak plasma radiation diagnostics: SXR poloidal tomography

    NASA Astrophysics Data System (ADS)

    Chernyshova, Maryna; Malinowski, Karol; Zió?kowski, Adam; Kowalska-Strzeciwilk, Ewa; Czarski, Tomasz; Po?niak, Krzysztof T.; Kasprowicz, Grzegorz; Zabo?otny, Wojciech; Woje?ski, Andrzej; Kolasi?ski, Piotr; Krawczyk, Rafa? D.

    2015-09-01

    An increased attention to tungsten material is related to a fact that it became a main candidate for the plasma facing material in ITER and future fusion reactor. The proposed work refers to the studies of W influence on the plasma performances by developing new detectors based on Gas Electron Multiplier GEM) technology for tomographic studies of tungsten transport in ITER-oriented tokamaks, e.g. WEST project. It presents current stage of design and developing of cylindrically bent SXR GEM detector construction for horizontal port implementation. Concept to overcome an influence of constraints on vertical port has been also presented. It is expected that the detecting unit under development, when implemented, will add to the safe operation of tokamak bringing creation of sustainable nuclear fusion reactors a step closer.

  16. Transient and steady-state dark current mechanisms in amorphous selenium avalanche radiation detectors

    SciTech Connect

    Kabir, M. Z.; Imam, Safayat-Al

    2013-04-15

    A theoretical model for describing bias-dependent transient and steady-state behaviors of dark current in amorphous selenium (a-Se) avalanche detector structures has been developed. The analytical model considers bulk thermal generation current from mid-gap sates, transient carrier depletion, and carrier injection from the electrodes incorporating avalanche multiplication. The proposed physics-based dark current model is compared with the published experimental results on three potential a-Se avalanche detector structures. The steady-state dark current is the minimum for the structures that have effective blocking layers for both holes and electrons. The transient decay time to reach a plateau decreases considerably with increasing electric field.

  17. Growth, characterization and spectroscopic investigations of InI crystals for optical and radiation detector applications

    SciTech Connect

    Mandal, K.C.; Klugerman, M.; Cirignano, L.J.; Moy, L.P.; Shah, K.S.; Squillante, M.R.; Bhattacharyya, R.N.

    1998-12-31

    Single crystals of InI (E{sub g} = 2.01 eV at 300 K) have been grown by vertical Bridgman technique using zone refined (ZR) starting materials. The quality of the grown crystal has been evaluated by X-ray diffraction (XRD), Electron probe microanalysis (EPMA) and Photoelectron spectroscopy (XPS). Chemically etched crystal wafer has been used to fabricate optical and nuclear detectors. The results are presented in this paper.

  18. Stabilized thallium bromide radiation detectors and methods of making the same

    SciTech Connect

    Leao, Cedric Rocha; Lordi, Vincenzo

    2015-11-24

    According to one embodiment, a crystal includes thallium bromide (TlBr), one or more positively charged dopants, and one or more negatively charged dopants. According to another embodiment, a system includes a monolithic crystal including thallium bromide (TlBr), one or more positively charged dopants, and one or more negatively charged dopants; and a detector configured to detect a signal response of the crystal.

  19. Waveguide integrated superconducting single-photon detectors implemented as near-perfect absorbers of coherent radiation.

    PubMed

    Akhlaghi, Mohsen K; Schelew, Ellen; Young, Jeff F

    2015-01-01

    At the core of an ideal single-photon detector is an active material that absorbs and converts every incident photon to a discriminable signal. A large active material favours efficient absorption, but often at the expense of conversion efficiency, noise, speed and timing accuracy. In this work, short (8.5??m long) and narrow (8 × 35?nm(2)) U-shaped NbTiN nanowires atop silicon-on-insulator waveguides are embedded in asymmetric nanobeam cavities that render them as near-perfect absorbers despite their small volume. At 2.05?K, when biased at 0.9 of the critical current, the resulting superconducting single-photon detectors achieve a near-unity on-chip quantum efficiency for ?1,545?nm photons, an intrinsic dark count rate <0.1?Hz, a reset time of ?7?ns, and a timing jitter of ?55?ps full-width at half-maximum. Such ultracompact, high-performance detectors are essential for progress in integrated quantum optics. PMID:26359204

  20. Waveguide integrated superconducting single-photon detectors implemented as near-perfect absorbers of coherent radiation

    NASA Astrophysics Data System (ADS)

    Akhlaghi, Mohsen K.; Schelew, Ellen; Young, Jeff F.

    2015-09-01

    At the core of an ideal single-photon detector is an active material that absorbs and converts every incident photon to a discriminable signal. A large active material favours efficient absorption, but often at the expense of conversion efficiency, noise, speed and timing accuracy. In this work, short (8.5 ?m long) and narrow (8 × 35 nm2) U-shaped NbTiN nanowires atop silicon-on-insulator waveguides are embedded in asymmetric nanobeam cavities that render them as near-perfect absorbers despite their small volume. At 2.05 K, when biased at 0.9 of the critical current, the resulting superconducting single-photon detectors achieve a near-unity on-chip quantum efficiency for ~1,545 nm photons, an intrinsic dark count rate <0.1 Hz, a reset time of ~7 ns, and a timing jitter of ~55 ps full-width at half-maximum. Such ultracompact, high-performance detectors are essential for progress in integrated quantum optics.

  1. Multipurpose Radiation Resistant Semiconductor Detectors for Alpha, Neutron & Low Energy Gamma Ray Measurements at High Temperatures in High-Intensity Gamma Ray

    SciTech Connect

    Ruddy, Frank H.

    2005-06-01

    Work scheduled under year two of DOE Grant DE-FG02-04ER63734 is on schedule and all year-two milestones have or will be met. Results to date demonstrate that unprecedented silicon carbide (SiC) energy resolution has been obtained, and that SiC detectors may achieve energy resolution that exceeds that obtainable with the best silicon alpha spectrometers. Fast-neutron energy spectrometry measurements indicate that recoil-ion energy spectrometry should be possible with SiC detectors. Furthermore, SiC detectors have been demonstrated to perform well even after gamma-ray exposures of 1.E09 Rad. This result and the previously demonstrated capability of SiC detectors to operate in elevated-temperature environments are very promising for potential DOE EMSP applications. A new class of multipurpose, radiation-resistant semiconductor detectors that can be used in elevated-temperature and high-radiation environments is being developed under this grant. These detectors, based on silicon carbide (SiC) semiconductor are designed to have larger active volumes than previously available SiC detectors, and are being tested for their response to alpha particles, X-rays and low energy gamma rays, and fast neutrons. Specifically, SiC radiation detectors with larger areas and 100-micrometer thick active regions have been designed and manufactured according to detector-design specifications. Detectors based on a Schottky diode design were specified in order to minimize the effects of the detector entrance window on alpha particle measurements. During manufacture of the Schottky diodes, the manufacturer also provided a set of large-volume SiC p-i-n diodes for testing Extensive alpha particle measurements have been carried out to test and quantify the response of the SiC Schottky diodes. Exposures to 148-Gd, 213-Po, 217-At, 221-Fr, 225-Ac, 237-Np, 238-Pu, 240-Pu, and 242-Pu sources were used to obtain detailed alpha response data in the alpha energy range from 3182.787 keV to 8375.9 keV. The 148-Gd, 213-Po, 217-At, and 221-Fr sources provide energy-separated, mono-energetic alpha particle peaks which can be analyzed to provide detailed information on the energy response characteristics of the detectors.

  2. An InGaAs detector based radiation thermometer and fixed-point blackbodies for temperature scale realization at NIM

    NASA Astrophysics Data System (ADS)

    Hao, X.; Yuan, Z.; Wang, J.; Lu, X.

    2013-09-01

    In this paper, we describe an InGaAs detector based radiation thermometer (IRT) and new design of fixed-point blackbodies, including Sn, Zn, Al and Cu, for the establishment of a temperature scale from 200 °C to 1085 °C at the National Institute of Metrology of China. The construction and calibration of the IRT with the four fixed-point blackbodies are described. Characteristics of the IRT, such as the size-of-source effect, the amplifier performance and its stability are determined. The design of the four fixed-points, with 10 mm diameter of aperture and 0.9999 emissivity, is described. The uncertainty of the scale realization is elaborated.

  3. An InGaAs detector based radiation thermometer and fixed-point blackbodies for temperature scale realization at NIM

    SciTech Connect

    Hao, X.; Yuan, Z.; Wang, J.; Lu, X.

    2013-09-11

    In this paper, we describe an InGaAs detector based radiation thermometer (IRT) and new design of fixed-point blackbodies, including Sn, Zn, Al and Cu, for the establishment of a temperature scale from 200 °C to 1085 °C at the National Institute of Metrology of China. The construction and calibration of the IRT with the four fixed-point blackbodies are described. Characteristics of the IRT, such as the size-of-source effect, the amplifier performance and its stability are determined. The design of the four fixed-points, with 10 mm diameter of aperture and 0.9999 emissivity, is described. The uncertainty of the scale realization is elaborated.

  4. The use of a high-purity germanium detector for routine measurements of {sup 125}I in radiation workers

    SciTech Connect

    Kopp, P.; Bergmann, H.; Havlik, E.; Aiginger, H.; Unfried, E.; Riedlmayer, L.

    1994-12-01

    A high-purity germanium detector was calibrated for the assessment of {sup 125}I uptake in the thyroid gland of radiation workers. A cylindrical water phantom (perspex walls) with high flexibility for position and size of the thyroid was constructed. Within a massive shielding chamber built for a whole-body counter, an activity of 2.2 Bq was detectable (MDA). This is well below the very restrictive limiting value of 20 Bq for inhalation specified by Austrian law. An activity of 128 Bq was measured with a statistical uncertainty of 5% in a counting period of 10 min. Various parameters influencing the result are investigated as well as the performance of two other measurement geometries outside the shielding chamber. 13 refs., 4 figs., 2 tabs.

  5. Measurement of the energy response function of a silicon pixel detector readout by a Timepix chip using synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Schioppa, E., Jr.; Banerjee, D.; Visser, J.; Klaver, T.; Koffeman, E.; Bras, W.

    2014-08-01

    In view of applications in X-ray spectral computed tomography, we determine the energy response function of a 300 ?m thick silicon pixel detector, read out by a Timepix ASIC, for a wide range of energies, by using synchrotron radiation in the range 5-32.5 keV. We employ a simple analytical model of the charge transport in the sensor to fit the data and to parametrize the energy response function. This allows to interpolate the function between the energies at which the measurements were performed and to extrapolate it outside the experimentally accessible range. The response function thus parametrized is used to predict how an incoming X-ray spectrum will be distorted during the detection process in the sensor. The comparison of the calculation with measurements shows good agreement.

  6. Development of an active detector for the characterization of the late-time radiation environment from a reactor pulse

    SciTech Connect

    Luker, S.M.; Griffin, P.J.; Kolb, N.R.; Naranjo, G.N.; Suo-Anttila, A.J.

    2011-07-01

    Document available in abstract form only, full text of document follows: This paper discusses the use of a commercially available {sup 235}U fission chamber, with a matching compensating ion chamber, originally sold as a single-ended detector with the signal conducted over the shield of a coaxial cable. The authors designed an aluminum housing that isolates the two detectors and converts the signals to full differential mode as a noise-reduction technique. The signals are processed using the switched resistor technique to extend the signal range to longer times from the peak of the pulse [Luker, S. M., Griffin, P. J., King, D. B., and Suo-Anttila, A. J., 'Improved Diagnostics for Analysis of a Reactor Pulse Radiation Environment,' 13. International Symposium on Reactor Dosimetry, Akersloot, Netherlands, May 25, 2008, pp. 4-6.]. The newly configured fission chamber assembly has been used at the annular core research reactor at Sandia National Laboratories to provide a high-fidelity characterization of the neutron time profile from a pulsed operation. (authors)

  7. Extended mode in blocked impurity band detectors for terahertz radiation detection

    SciTech Connect

    Liao, K. S.; Li, N.; Wang, C.; Li, L.; Jing, Y. L.; Wen, J.; Li, M. Y.; Wang, H.; Zhou, X. H. Li, Z. F.; Lu, W.

    2014-10-06

    We demonstrate the existence of an interfacial barrier in blocked impurity band (BIB) detectors using temperature-dependent dark current and corresponding theoretical calculations. Considering the effects of the interfacial barrier, the calculated photoresponse is in good agreement with the experimental results. A dual-excitation model, including the direct excitation over the full barrier and excitation to the band minimum with subsequent tunneling into the blocking layer, is proposed to quantitatively explain the observed photoresponse extension. A concept of extended-mode detection is developed to suggest the option for some selective photoresponse in the terahertz region and open the possibility of extending BIB photoresponse to lower frequency.

  8. Extracting trap parameters from PICTS spectra in cadmium zinc telluride radiation detector material

    SciTech Connect

    Toney, J.E.; Brunett, B.A.; Schlesinger, T.E.; James, R.B.

    1998-12-31

    The authors demonstrate that the regularization method due to Weese can resolve closely-spaced peaks in PICTS spectra for cadmium zinc telluride. They also show that electron and hole traps can be distinguished from each other by the bias dependence of the spectrum when using an excitation source that is primarily infrared but which contains a small component of visible light. Lastly, they show that there are qualitative differences between PICTS spectra taken with infrared excitation and those taken with visible excitation. They attribute the surface-related levels to diffusion into the detector material of gold from electroless deposition of contacts.

  9. Radiation tolerance of a high quality synthetic single crystal chemical vapor deposition diamond detector irradiated by 14.8 MeV neutrons

    NASA Astrophysics Data System (ADS)

    Pillon, M.; Angelone, M.; Aielli, G.; Almaviva, S.; Marinelli, Marco; Milani, E.; Prestopino, G.; Tucciarone, A.; Verona, C.; Verona-Rinati, G.

    2008-09-01

    Diamond exhibits many properties such as an outstanding radiation hardness and fast response time both important to design detectors working in extremely radioactive environments. Among the many applications these devices can be used for, there is the development of a fast and radiation hard neutron detector for the next generation of fusion reactors, such as the International Thermonuclear Experimental Reactor project, under construction at Cadarache in France. A technology to routinely produce electronic grade synthetic single crystal diamond detectors was recently developed by our group. One of such detectors, with an energy resolution of 0.9% as measured using an A241m ? particle source, has been heavily irradiated with 14.8 MeV neutrons produced by the Frascati Neutron Generator. The modifications of its spectroscopic properties have been studied as a function of the neutron fluence up to 2.0×1014 n/cm2. In the early stage of the irradiation procedure an improvement in the spectroscopic performance of the detector was observed. Subsequently the detection performance remains stable for all the given neutron fluence up to the final one thus assessing a remarkable radiation hardness of the device. The neutron damage in materials has been calculated and compared with the experimental results. This comparison is discussed within the nonionizing energy loss (NIEL) hypothesis, which states that performance degradation is proportional to NIEL.

  10. Radiation tolerance of a high quality synthetic single crystal chemical vapor deposition diamond detector irradiated by 14.8 MeV neutrons

    SciTech Connect

    Pillon, M.; Angelone, M.; Aielli, G.; Almaviva, S.; Marinelli, Marco; Milani, E.; Prestopino, G.; Tucciarone, A.; Verona, C.; Verona-Rinati, G.

    2008-09-01

    Diamond exhibits many properties such as an outstanding radiation hardness and fast response time both important to design detectors working in extremely radioactive environments. Among the many applications these devices can be used for, there is the development of a fast and radiation hard neutron detector for the next generation of fusion reactors, such as the International Thermonuclear Experimental Reactor project, under construction at Cadarache in France. A technology to routinely produce electronic grade synthetic single crystal diamond detectors was recently developed by our group. One of such detectors, with an energy resolution of 0.9% as measured using an {sup 241}Am{alpha} particle source, has been heavily irradiated with 14.8 MeV neutrons produced by the Frascati Neutron Generator. The modifications of its spectroscopic properties have been studied as a function of the neutron fluence up to 2.0x10{sup 14} n/cm{sup 2}. In the early stage of the irradiation procedure an improvement in the spectroscopic performance of the detector was observed. Subsequently the detection performance remains stable for all the given neutron fluence up to the final one thus assessing a remarkable radiation hardness of the device. The neutron damage in materials has been calculated and compared with the experimental results. This comparison is discussed within the nonionizing energy loss (NIEL) hypothesis, which states that performance degradation is proportional to NIEL.

  11. An analytical model of radiation-induced Charge Transfer Inefficiency for CCD detectors

    NASA Astrophysics Data System (ADS)

    Short, A.; Crowley, C.; de Bruijne, J. H. J.; Prod'homme, T.

    2013-04-01

    The European Space Agency's Gaia mission is scheduled for launch in 2013. It will operate at L2 for 5 years, rotating slowly to scan the sky so that its two optical telescopes will repeatedly observe more than one billion stars. The resulting data set will be iteratively reduced to solve for the position, parallax and proper motion of every observed star. The focal plane contains 106 large area silicon CCDs continuously operating in a mode where the line transfer rate and the satellite rotation are in synchronization. One of the greatest challenges facing the mission is radiation damage to the CCDs which will cause charge deferral and image shape distortion. This is particularly important because of the extreme accuracy requirements of the mission. Despite steps taken at hardware level to minimize the effects of radiation, the residual distortion will need to be calibrated during the pipeline data processing. Due to the volume and inhomogeneity of data involved, this requires a model which describes the effects of the radiation damage which is physically realistic, yet fast enough to implement in the pipeline. The resulting charge distortion model was developed specifically for the Gaia CCD operating mode. However, a generalized version is presented in this paper and this has already been applied in a broader context, for example to investigate the impact of radiation damage on the Euclid dark-energy mission data.

  12. Assessment of radiation doses from residential smoke detectors that contain americium-241

    SciTech Connect

    O'Donnell, F.R.; Etnier, E.L.; Holton, G.A.; Travis, C.C.

    1981-10-01

    External dose equivalents and internal dose commitments were estimated for individuals and populations from annual distribution, use, and disposal of 10 million ionization chamber smoke detectors that contain 110 kBq (3 ..mu..Ci) americium-241 each. Under exposure scenarios developed for normal distribution, use, and disposal using the best available information, annual external dose equivalents to average individuals were estimated to range from 4 fSv (0.4 prem) to 20 nSv (2 ..mu..rem) for total body and from 7 fSv to 40 nSv for bone. Internal dose commitments to individuals under post disposal scenarios were estimated to range from 0.006 to 80 ..mu..Sv (0.0006 to 8 mrem) to total body and from 0.06 to 800 ..mu..Sv to bone. The total collective dose (the sum of external dose equivalents and 50-year internal dose commitments) for all individuals involved with distribution, use, or disposal of 10 million smoke detectors was estimated to be about 0.38 person-Sv (38 person-rem) to total body and 00 ft/sup 2/).

  13. Dead-time effects of neutron detectors due to pulsed radiation.

    PubMed

    Ott, K; Helmecke, M; Luszik-Bhadra, M; Martin, M; Weber, A

    2013-07-01

    Electron storage rings of synchrotron light sources are typically filled only for several minutes day(-1). During these injections, the dose rates outside the shielding walls can be quite high even if the annual dose personal dose equivalent is below 1 mSv a(-1), which is the case at most synchrotron light sources. During the injection process, there is a time structure of short pulses (often defined by the convolution time of the synchrotron) having a pulse length of several 100 ns and a repetition rate between 1 and 10 Hz, which is defined by the acceleration processes in synchrotrons or linacs. Under these conditions, high measurement errors are possible, especially for neutron monitors that are based on proportional counters, which is the case for most commercially available neutron detectors. In this article, the authors' investigations of different neutron monitors are presented and how these results depend on the beam parameters, neutron fields and detector properties is shown. The experiments were conducted at the synchrotron light sources BESSYII and Metrology Light Source with pulsed electron beams of 1.7 GeV and 100 MeV, respectively. Other experiments were conducted at the HZB cyclotron with a 68-MeV pulsed proton beam that hits a spallation target. Fluka calculations of dose rates and neutron spectra were performed for the experiments. Correction formulas that are valid even in the saturation range were derived. PMID:23241424

  14. Research Update: Reactively sputtered nanometer-thin ZrN film as a diffusion barrier between Al and boron layers for radiation detector applications

    SciTech Connect

    Golshani, Negin Mohammadi, V.; Schellevis, H.; Beenakker, C. I. M.; Ishihara, R.

    2014-10-01

    In this paper, optimization of the process flow for PureB detectors is investigated. Diffusion barrier layers between a boron layer and the aluminum interconnect can be used to enhance the performance and visual appearance of radiation detectors. Few nanometers-thin Zirconium Nitride (ZrN) layer deposited by reactive sputtering in a mixture of Ar/N{sub 2}, is identified as a reliable diffusion barrier with better fabrication process compatibility than others. The barrier properties of this layer have been tested for different boron layers deposited at low and high temperatures with extensive optical microscopy analyses, electron beam induced current, SEM, and electrical measurements. This study demonstrated that spiking behavior of pure Al on Si can be prevented by the thin ZrN layer thus improving the performance of the radiation detectors fabricated using boron layer.

  15. Single-crystalline Bi2Sr2CaCu2O8+x detectors for direct detection of microwave radiation

    NASA Astrophysics Data System (ADS)

    Li, M.; Winkler, D.; Yurgens, A.

    2015-04-01

    We test radiation detectors made from single-crystalline Bi2Sr2CaCu2O8+x flakes put on oxidized Si substrates. The 100-nm-thick flakes are lithographically patterned into 4 ×12 ?m2 large rectangles embedded in thin-film log-spiral antennas. The SiO2 layer weakens the thermal link between the flakes and the bath. Two modes of radiation detection have been observed. For a bolometric type of sensors a responsivity of ˜300 V/W and a noise equivalent power of 30 nW/ ?{Hz } has been deduced at 70 K. Much more sensitive is the non-bolometric device showing characteristics similar to a Golay-type detector while being at least a thousand times faster. Making smaller (sub-?m) structures is expected to significantly improve the performance of these devices and makes them very competitive among other microwave and terahertz detectors.

  16. Research Update: Reactively sputtered nanometer-thin ZrN film as a diffusion barrier between Al and boron layers for radiation detector applications

    NASA Astrophysics Data System (ADS)

    Golshani, Negin; Mohammadi, V.; Schellevis, H.; Beenakker, C. I. M.; Ishihara, R.

    2014-10-01

    In this paper, optimization of the process flow for PureB detectors is investigated. Diffusion barrier layers between a boron layer and the aluminum interconnect can be used to enhance the performance and visual appearance of radiation detectors. Few nanometers-thin Zirconium Nitride (ZrN) layer deposited by reactive sputtering in a mixture of Ar/N2, is identified as a reliable diffusion barrier with better fabrication process compatibility than others. The barrier properties of this layer have been tested for different boron layers deposited at low and high temperatures with extensive optical microscopy analyses, electron beam induced current, SEM, and electrical measurements. This study demonstrated that spiking behavior of pure Al on Si can be prevented by the thin ZrN layer thus improving the performance of the radiation detectors fabricated using boron layer.

  17. Shielded Heavy-Ion Environment Linear Detector (SHIELD): an experiment for the Radiation and Technology Demonstration (RTD) Mission

    NASA Technical Reports Server (NTRS)

    Shavers, M. R.; Cucinotta, F. A.; Miller, J.; Zeitlin, C.; Heilbronn, L.; Wilson, J. W.; Singleterry, R. C. Jr

    2001-01-01

    Radiological assessment of the many cosmic ion species of widely distributed energies requires the use of theoretical transport models to accurately describe diverse physical processes related to nuclear reactions in spacecraft structures, planetary atmospheres and surfaces, and tissues. Heavy-ion transport models that were designed to characterize shielded radiation fields have been validated through comparison with data from thick-target irradiation experiments at particle accelerators. With the RTD Mission comes a unique opportunity to validate existing radiation transport models and guide the development of tools for shield design. For the first time, transport properties will be measured in free-space to characterize the shielding effectiveness of materials that are likely to be aboard interplanetary space missions. Target materials composed of aluminum, advanced composite spacecraft structure and other shielding materials, helium (a propellant) and tissue equivalent matrices will be evaluated. Large solid state detectors will provide kinetic energy and charge identification for incident heavy-ions and for secondary ions created in the target material. Transport calculations using the HZETRN model suggest that 8 g cm -2 thick targets would be adequate to evaluate the shielding effectiveness during solar minimum activity conditions for a period of 30 days or more.

  18. A study of angular instability due to radiation pressure in LIGO gravitational wave detector

    NASA Astrophysics Data System (ADS)

    Hirose, Eiichi

    2008-08-01

    We observed the effect of radiation pressure on the angular sensing and control system of the Laser Interferometer Gravitational-Wave Observatory (LIGO) interferometer's core optics at LIGO Hanford Observatory. This is the first measurement of this effect in a complete gravitational wave interferometer. Only one of the two angular modes survives with feedback control, since the other mode is suppressed when the control gain is sufficiently large. We developed a mathematical model to understand the physics of the system. The model indicates that the current system has substantial margin for higher laser power; angular instability due to radiation pressure won't occur until laser power reaches about eight times the power used in the initial LIGO configuration. This analysis was based on the degrees of freedom associated with differential motion between the mirrors in the interferometer's two arms. A more complete analysis including the common mode degrees of freedom will be left for future work.

  19. Reconstruction of a Radiation Point Source's Radial Location Using Goodness-of-Fit Test on Spectra Obtained from an HPGe Detector

    E-print Network

    L. T. Evans; K. Andre; R. De; R. Henning; E. D. Morgan

    2009-08-16

    High purity germanium (HPGe) detectors are ubiquitous in nuclear physics experiments and are also used in numerous low radioactive background detectors. The effect of the position of $^{60}$Co and $^{137}$Cs point sources on the shape of spectra were studied with Monte Carlo and HPGe detector measurements. We briefly confirm previous work on the position dependence of relative heights of peaks. Spectra taken with the radiation sources placed at locations around the detector were then compared using the Kolmogorov-Smirnov (K-S) goodness-of-fit test. We demonstrate that with this method the Compton continuum spectral shape has good sensitivity to the radial location of a point-source, but poor angular resolution. We conclude with a study of the position reconstruction accuracy as a function of the number of counts from the source.

  20. Temporal and temperature evolution of electric field in CdTe:In radiation detectors

    SciTech Connect

    D?di?, V. Zázvorka, J.; Rejhon, M.; Franc, J.; Grill, R.; Sellin, P. J.

    2014-08-07

    We employed measurement of the Pockels electro-optic effect to study the electric field and space charge dynamics in semi-insulating CdTe doped with indium. We performed measurements of time and temperature dependence of the electric field. The polarization due to space charge build-up decreases with increasing temperature. Increase of temperature, therefore, leads to de-polarization in CdTe:In detectors which are opposite to the CdTe:Cl samples studied to date. We have shown that the thermally activated depolarization cannot be explained by the conventional model used for the description of space charge formation so far and an alternative model involving a recombination level was suggested and successfully used.

  1. Application of a-Si:H radiation detectors in medical imaging

    SciTech Connect

    Lee, Hyoung-Koo

    1995-06-01

    Monte Carlo simulations of a proposed a-Si:H-based current-integrating gamma camera were performed. The analysis showed that the intrinsic resolution of such a camera was 1 {approximately} 2.5 mm, which is somewhat better than that of a conventional gamma camera, and that the greater blurring, due to the detection of scattered {gamma}-rays, could be reduced considerably by image restoration techniques. This proposed gamma camera would be useful for imaging shallow organs such as the thyroid. Prototype charge-storage a-Si:H pixel detectors for such a camera were designed, constructed and tested. The detectors could store signal charge as long as 5 min at {minus}26C. The thermal generation current in reverse biased a-Si:H p-i-n photodetectors was investigated, and the Poole-Frenkel effect was found to be the most significant source of the thermal generation current. Based on the Poole-Frenkel effect, voltage- and time-dependent thermal generation current was modeled. Using the model, the operating conditions of the proposed a-Si:H gamma camera, such as the operating temperature, the operating bias and the {gamma}-scan period, could be predicted. The transient photoconductive gain mechanism in various a-Si:H devices was investigated for applications in digital radiography. Using the a-Si:H photoconductors in n-i-n configuration in pixel arrays, enhancement in signal collection (more than 200 times higher signal level) can be achieved in digital radiography, compared to the ordinary p-i-n type a-Si:H x-ray imaging arrays.

  2. A Dual-Sided Coded-Aperture Radiation Detection System , Nuclear Instruments & Methods in Physics Research Section A-Accelerators Spectrometers Detectors and Associated Equipment

    SciTech Connect

    Ziock, Klaus-Peter; Fabris, Lorenzo

    2010-01-01

    We report the development of a large-area, mobile, coded-aperture radiation imaging system for localizing compact radioactive sources in three dimensions while rejecting distributed background. The 3D Stand-Off Radiation Detection System (SORDS-3D) has been tested at speeds up to 95 km/h and has detected and located sources in the millicurie range at distances of over 100 m. Radiation data are imaged to a geospatially mapped world grid with a nominal 1.25- to 2.5-m pixel pitch at distances out to 120 m on either side of the platform. Source elevation is also extracted. Imaged radiation alarms are superimposed on a side-facing video log that can be played back for direct localization of sources in buildings in urban environments. The system utilizes a 37-element array of 5 x 5 x 50 cm{sup 3} cesium-iodide (sodium) detectors. Scintillation light is collected by a pair of photomultiplier tubes placed at either end of each detector, with the detectors achieving an energy resolution of 6.15% FWHM (662 keV) and a position resolution along their length of 5 cm FWHM. The imaging system generates a dual-sided two-dimensional image allowing users to efficiently survey a large area. Imaged radiation data and raw spectra are forwarded to the RadioNuclide Analysis Kit (RNAK), developed by our collaborators, for isotope ID. An intuitive real-time display aids users in performing searches. Detector calibration is dynamically maintained by monitoring the potassium-40 peak and digitally adjusting individual detector gains. We have recently realized improvements, both in isotope identification and in distinguishing compact sources from background, through the installation of optimal-filter reconstruction kernels.

  3. Diamond detectors in particle physics

    NASA Astrophysics Data System (ADS)

    Tapper, R. J.

    2000-08-01

    Particle detectors made from artificial diamond have great promise for future experiments in particle physics because they are far less vulnerable to radiation damage than any other detector type. We review the history of diamond detectors and describe their current state of development. We also discuss the evidence which proves the resistance of these detectors to damage by various forms of incident radiation.

  4. Chemical vapor deposition diamond based multilayered radiation detector: Physical analysis of detection properties

    SciTech Connect

    Almaviva, S.; Marinelli, Marco; Milani, E.; Prestopino, G.; Tucciarone, A.; Verona, C.; Verona-Rinati, G.; Angelone, M.; Pillon, M.; Dolbnya, I.; Sawhney, K.; Tartoni, N.

    2010-01-15

    Recently, solid state photovoltaic Schottky diodes, able to detect ionizing radiation, in particular, x-ray and ultraviolet radiation, have been developed at the University of Rome 'Tor Vergata'. We report on a physical and electrical properties analysis of the device and a detailed study of its detection capabilities as determined by its electrical properties. The design of the device is based on a metal/nominally intrinsic/p-type diamond layered structure obtained by microwave plasma chemical vapor deposition of homoepitaxial single crystal diamond followed by thermal evaporation of a metallic contact. The device can operate in an unbiased mode by using the built-in potential arising from the electrode-diamond junction. We compare the expected response of the device to photons of various energies calculated through Monte Carlo simulation with experimental data collected in a well controlled experimental setup i.e., monochromatic high flux x-ray beams from 6 to 20 keV, available at the Diamond Light Source synchrotron in Harwell (U.K.).

  5. Multipurpose Radiation Resistant Semiconductor Detectors for Alpha, Neutron & Low Energy Gamma Ray Measurements at High Temperatures in High-Intensity Gamma Ray

    SciTech Connect

    Ruddy, Frank H

    2005-06-01

    Work scheduled under year two of DOE Grant DE-FG02-04ER63734 is on schedule and all year-two milestones have or will be met. Results to date demonstrate that unprecedented silicon carbide (SiC) energy resolution has been obtained, and that SiC detectors may achieve energy resolution that exceeds that obtainable with the best silicon alpha spectrometers. Fast-neutron energy spectrometry measurements indicate that recoil-ion energy spectrometry should be possible with SiC detectors. Furthermore, SiC detectors have been demonstrated to perform well even after gamma-ray exposures of 1.E09 Rad. This result and the previously demonstrated capability of SiC detectors to operate in elevated-temperature environments are very promising for potential DOE EMSP applications. A new class of multipurpose, radiation-resistant semiconductor detectors that can be used in elevated-temperature and high-radiation environments is being developed under this grant.

  6. SU-F-BRE-01: A Rapid Method to Determine An Upper Limit On a Radiation Detector's Correction Factor During the QA of IMRT Plans

    SciTech Connect

    Kamio, Y; Bouchard, H

    2014-06-15

    Purpose: Discrepancies in the verification of the absorbed dose to water from an IMRT plan using a radiation dosimeter can be wither caused by 1) detector specific nonstandard field correction factors as described by the formalism of Alfonso et al. 2) inaccurate delivery of the DQA plan. The aim of this work is to develop a simple/fast method to determine an upper limit on the contribution of composite field correction factors to these discrepancies. Methods: Indices that characterize the non-flatness of the symmetrised collapsed delivery (VSC) of IMRT fields over detector-specific regions of interest were shown to be correlated with IMRT field correction factors. The indices introduced are the uniformity index (UI) and the mean fluctuation index (MF). Each one of these correlation plots have 10 000 fields generated with a stochastic model. A total of eight radiation detectors were investigated in the radial orientation. An upper bound on the correction factors was evaluated by fitting values of high correction factors for a given index value. Results: These fitted curves can be used to compare the performance of radiation dosimeters in composite IMRT fields. Highly water-equivalent dosimeters like the scintillating detector (Exradin W1) and a generic alanine detector have been found to have corrections under 1% over a broad range of field modulations (0 – 0.12 for MF and 0 – 0.5 for UI). Other detectors have been shown to have corrections of a few percent over this range. Finally, a full Monte Carlo simulations of 18 clinical and nonclinical IMRT field showed good agreement with the fitted curve for the A12 ionization chamber. Conclusion: This work proposes a rapid method to evaluate an upper bound on the contribution of correction factors to discrepancies found in the verification of DQA plans.

  7. Thick amorphous silicon layers suitable for the realization of radiation detectors

    SciTech Connect

    Hong, Wan-Shick; Drewery, J.S.; Jing, Tao; Lee, Hyong-Koo; Perez-Mendez, V.; Petrova-Koch, V.

    1995-04-01

    Thick silicon films with good electronic quality have been prepared by glow discharge of He-diluted SiH{sub 4} at a substrate temperature {approximately} 150{degree}C and subsequent annealing at 160{degree}C for about 100 hours. The stress in the films obtained this way decreased to {approximately} 100 MPa compared to the 350 MPa in conventional a-Si:H. The post-annealing helped to reduce the ionized dangling bond density from 2.5 {times} 10{sup 15} cm{sup {minus}3} to 7 {times} 10{sup 14} cm{sup {minus}3} without changing the internal stress. IR spectroscopy and hydrogen effusion measurements implied the existence of microvoids and tiny crystallites in the material showing satisfactory electronic properties. P-I-N diodes for radiation detection applications have been realized out of the new material.

  8. Terahertz Radiation Heterodyne Detector Using Two-Dimensional Electron Gas in a GaN Heterostructure

    NASA Technical Reports Server (NTRS)

    Karasik, Boris S.; Gill, John J.; Mehdi, Imran; Crawford, Timothy J.; Sergeev, Andrei V.; Mitin, Vladimir V.

    2012-01-01

    High-resolution submillimeter/terahertz spectroscopy is important for studying atmospheric and interstellar molecular gaseous species. It typically uses heterodyne receivers where an unknown (weak) signal is mixed with a strong signal from the local oscillator (LO) operating at a slightly different frequency. The non-linear mixer devices for this frequency range are unique and are not off-the-shelf commercial products. Three types of THz mixers are commonly used: Schottky diode, superconducting hot-electron bolometer (HEB), and superconductor-insulation-superconductor (SIS) junction. A HEB mixer based on the two-dimensional electron gas (2DEG) formed at the interface of two slightly dissimilar semiconductors was developed. This mixer can operate at temperatures between 100 and 300 K, and thus can be used with just passive radiative cooling available even on small spacecraft.

  9. Personal radiation detector at a high technology readiness level that satisfies DARPA's SN-13-47 and SIGMA program requirements

    NASA Astrophysics Data System (ADS)

    Ginzburg, D.; Knafo, Y.; Manor, A.; Seif, R.; Ghelman, M.; Ellenbogen, M.; Pushkarsky, V.; Ifergan, Y.; Semyonov, N.; Wengrowicz, U.; Mazor, T.; Kadmon, Y.; Cohen, Y.; Osovizky, A.

    2015-06-01

    There is a need to develop new personal radiation detector (PRD) technologies that can be mass produced. On August 2013, DARPA released a request for information (RFI) seeking innovative radiation detection technologies. In addition, on December 2013, a Broad Agency Announcement (BAA) for the SIGMA program was released. The RFI requirements focused on a sensor that should possess three main properties: low cost, high compactness and radioisotope identification capabilities. The identification performances should facilitate the detection of a hidden threat, ranging from special nuclear materials (SNM) to commonly used radiological sources. Subsequently, the BAA presented the specific requirements at an instrument level and provided a comparison between the current market status (state-of-the-art) and the SIGMA program objectives. This work presents an optional alternative for both the detection technology (sensor with communication output and without user interface) for DARPA's initial RFI and for the PRD required by the SIGMA program. A broad discussion is dedicated to the method proposed to fulfill the program objectives and to the selected alternative that is based on the PDS-GO design and technology. The PDS-GO is the first commercially available PRD that is based on a scintillation crystal optically coupled with a silicon photomultiplier (SiPM), a solid-state light sensor. This work presents the current performance of the instrument and possible future upgrades based on recent technological improvements in the SiPM design. The approach of utilizing the SiPM with a commonly available CsI(Tl) crystal is the key for achieving the program objectives. This approach provides the appropriate performance, low cost, mass production and small dimensions; however, it requires a creative approach to overcome the obstacles of the solid-state detector dark current (noise) and gain stabilization over a wide temperature range. Based on the presented results, we presume that the proposed approach of SiPM, with pixel size of 35 ?m, coupled to a scintillation material (for gamma and neutron detection) ensures the availability and low cost of the key components. Furthermore, automated manufacturing process enables mass production, thereby fulfilling the SIGMA program requirements, both as a sensor (assimilated with mobile device) and as a full detection device.

  10. Shaped detector

    SciTech Connect

    Carlson, R.W.

    1981-09-29

    A radiation detector or detector array which has a non-constant spatial response, is disclosed individually and in combination with a tomographic scanner. The detector has a first dimension which is oriented parallel to the plane of the scan circle in the scanner. Along the first dimension, the detector is most responsive to radiation received along a centered segment of the dimension and less responsive to radiation received along edge segments. This non-constant spatial response can be achieved in a detector comprised of a scintillation crystal and a photoelectric transducer. The scintillation crystal in one embodiment is composed of three crystals arranged in layers, with the center crystal having the greatest light conversion efficiency. In another embodiment, the crystal is covered with a reflective substance around the center segment and a less reflective substance around the remainder. In another embodiment, an optical coupling which transmits light from adjacent the center segment with the greatest intensity couples the scintillation crystal and the photoelectric transducer. In yet another embodiment, the photoelectric transducer comprises three photodiodes, one receiving light produced adjacent the central segment and the other two receiving light produced adjacent the edge segments. The outputs of the three photodiodes are combined with a differential amplifier.

  11. Development of a novel radiation imaging detector system for in vivo gene imaging in small animal studies

    SciTech Connect

    Weisenberger, A.G.; Majewski, S.; Bradley, E.L.

    1996-12-31

    Many studies in molecular biology deal with following the expression and regulation of a gene at different stages of an organism`s development or under different physiological conditions. Presently in situ hybridization and immunochemical assays are available to follow the gene expression at a single moment in time for one organism. One must sacrifice the organism to make a measurement, essentially taking a snap shot of the state of expression of the gene of interest. We have made progress on a new type of gene imaging technology which takes advantage of the emission properties of the radioisotope iodine 125 ({sup 125}I) as the probe and utilizes crystal scintillators and a position sensitive photomultiplier tube. Iodine 125 decays via electron capture emitting a 35 keV gamma-ray with the prompt emission of several 27-32 keV K{alpha} and K{beta} shell X-rays. Because of this a coincidence condition can be set to detect the {sup 125}I decays thus reducing background radiation contribution to the image. Mouse imaging studies of iodine uptake by the thyroid and melatonin receptor binding have been done with this detector system using low doses of {sup 125}I.

  12. Directional fast-neutron detector

    DOEpatents

    Byrd, Roger C. (Albuquerque, NM)

    1994-01-01

    A plurality of omnidirectional radiation detectors are arranged in a close packed symmetrical pattern to form a segmented detector. The output radiation counts from these detectors are arithmetically combined to provide the direction of a source of incident radiation. Directionality is achieved without the use of shielding to provide collimation and background reduction effects. Indeed, output counts from paired detectors are simply subtracted to yield a vector direction toward the radiation source. The counts from all of the detectors can be combined to yield an output signal functionally related to the radiation source strength.

  13. A low cost network of spectrometer radiation detectors based on the ArduSiPM a compact transportable Software/Hardware Data Acquisition system with Arduino DUE

    E-print Network

    Bocci, Valerio; Iacoangeli, Francesco; Nuccetelli, Massimo; Recchia, Luigi

    2015-01-01

    The necessity to use Photo Multipliers (PM) as light detector limited in the past the use of crystals in radiation handled device preferring the Geiger approach. The Silicon Photomultipliers (SiPMs) are very small and cheap, solid photon detectors with good dynamic range and single photon detection capability, they are usable to supersede in some application cumbersome and difficult to use Photo Multipliers (PM). A SiPM can be coupled with a scintillator crystal to build efficient, small and solid radiation detector. A cost effective and easily replicable Hardware software module for SiPM detector readout is made using the ArduSiPM solution [1]. The ArduSiPM is an easily battery operable handled device using an Arduino DUE (an open Software/Hardware board) as processor board and a piggy-back custom designed board (ArduSiPM Shield), the Shield contains all the blocks features to monitor, set and acquire the SiPM using internet network.

  14. Flame Detector

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Scientific Instruments, Inc. has now developed a second generation, commercially available instrument to detect flames in hazardous environments, typically refineries, chemical plants and offshore drilling platforms. The Model 74000 detector incorporates a sensing circuit that detects UV radiation in a 100 degree conical field of view extending as far as 250 feet from the instrument. It operates in a bandwidth that makes it virtually 'blind' to solar radiation while affording extremely high sensitivity to ultraviolet flame detection. A 'windowing' technique accurately discriminates between background UV radiation and ultraviolet emitted from an actual flame, hence the user is assured of no false alarms. Model 7410CP is a combination controller and annunciator panel designed to monitor and control as many as 24 flame detectors. *Model 74000 is no longer being manufactured.

  15. An XPS study of bromine in methanol etching and hydrogen peroxide passivation treatments for cadmium zinc telluride radiation detectors

    NASA Astrophysics Data System (ADS)

    Babar, S.; Sellin, P. J.; Watts, J. F.; Baker, M. A.

    2013-01-01

    The performance of single crystal CdZnTe radiation detectors is dependent on both the bulk and the surface properties of the material. After single crystal fabrication and mechanical polishing, modification of the surface to remove damage and reduce the surface leakage current is generally achieved through chemical etching followed by a passivation treatment. In this work, CdZnTe single crystals have been chemically etched using a bromine in methanol (BM) treatment. The BM concentrations employed were 0.2 and 2.0 (v/v) % and exposure times varied between 5 and 120 s. Angle resolved XPS and sputter depth profiling has been employed to characterize the surfaces for the different exposure conditions. A Te rich surface layer was formed for all exposures and the layer thickness was found to be independent of exposure time. The enriched Te layer thickness was accurately determined by calibrating the sputter rate against a CdTe layer of known thickness. For BM concentrations of 0.2 (v/v) % and 2 (v/v) %, the Te layer thickness was determined to be 1.3 ± 0.2 and 1.8 ± 0.2 nm, respectively. The BM etched surfaces have subsequently been passivated in a 30 wt.% H2O2 solution employing exposure time of 15 s. The oxide layer thickness has been calculated using two standard XPS methodologies, based on the Beer-Lambert expression. The TeO2 thickness calculated from ARXPS data are slightly higher than the thickness obtained by the simplified Beer-Lambert expression. For BM exposures of 30-120 s followed by a passivation treatment of 30 wt. % H2O2 solution employing an exposure time 15 s, the ARXPS method gave an average TeO2 thickness value of 1.20 nm and the simplified Beer-Lambert expression gave an average thickness value of 0.99 nm.

  16. Silicon Detectors

    NASA Astrophysics Data System (ADS)

    Sadrozinski, Hartmut

    2014-03-01

    The use of silicon detectors has experienced an exponential growth in accelerator and space based experiments, similar to trends in the semiconductor industry as a whole, usually paraphrased as ``Moore's Law.'' Some of the essentials for this phenomenon will be presented, together with examples of the exciting science results which it enabled. With the establishment of a ``semiconductor culture'' in universities and laboratories around the world, an increased understanding of the sensors results in thinner, faster, more radiation-resistant detectors, spawning an amazing wealth of new technologies and applications, which will be the main subject of the presentation.

  17. GADRAS Detector Response Function.

    SciTech Connect

    Mitchell, Dean J.; Harding, Lee; Thoreson, Gregory G; Horne, Steven M.

    2014-11-01

    The Gamma Detector Response and Analysis Software (GADRAS) applies a Detector Response Function (DRF) to compute the output of gamma-ray and neutron detectors when they are exposed to radiation sources. The DRF is fundamental to the ability to perform forward calculations (i.e., computation of the response of a detector to a known source), as well as the ability to analyze spectra to deduce the types and quantities of radioactive material to which the detectors are exposed. This document describes how gamma-ray spectra are computed and the significance of response function parameters that define characteristics of particular detectors.

  18. Measurement of terrestrial gamma radiation dose-rate (TGRD) level in soil samples from the district of Rembau, Malaysia, using high-purity Germanium detectors

    NASA Astrophysics Data System (ADS)

    Norbani, N. E.; Abdullah Salim, N. A.; Rahman, A. T. Abdul

    2014-11-01

    This study assesses the gamma radiation levels and associated dose rates from the naturally occurring radionuclides 232Th, 238U and 40K in soil samples collected from the district of Rembau, Malaysia using High-purity Germanium (HPGe) Detectors. A 105 measurement were performed on surface soil using NaI (Tl) gamma-ray detector with crystal size 1"x1", covering about 83% land of the Rembau district. The concentration of the naturally occurring radionuclides 232Th, 238U and 40K in soil samples collected were determined by using HPGe detector based on high-resolution gamma spectrometry system at Malaysia Nuclear Agency. The range of natural gamma radiation measured was from 114±14 nGy h-1 to 857±14 nGy h-1. The range of activity concentrations of U, Th and °K in soil from the studied areas varies from 151-401 Bq kg-1, 113-342 Bq kg-1 and 674-1526 Bq kg-1 with mean values of 245 Bq kg-1, 186 Bq kg-1 and 1152 Bq kg1 respectively. The mean values of terrestrial gamma radiation dose rate measured in Rembau district is 383±18 nGy h-1 compared to the Malaysian average is 92 nGy h-1 and world average is 59 nGy h-1 (UNSCEAR, 2000). The average annual dose from such terrestrial gamma radiation dose rates to an individual in Rembau district, assuming a tropical rural setting is estimated to be 0.78 mSv per year, which is considered to be within the normal range for doses from natural sources. An isodose map for the Rembau district has been plotted.

  19. Characteristics of a Frisch collar grid CdZnTe radiation detector grown by low-pressure Bridgman method

    NASA Astrophysics Data System (ADS)

    Jeong, Manhee; Jo, Woo Jin; Kim, Han Soo; Ha, Jang Ho

    2015-06-01

    A single-polarity charge-sensing method was studied by using a CdZnTe Frisch collar grid detector grown by using a low-pressure Bridgeman furnace at the Korea Atomic Energy Research Institute (KAERI). The Frisch collar grid CdZnTe detector has an active volume of 5 × 5 × 10 mm3, and was fabricated from a single crystal, Teflon tape and copper tape used as a Frisch collar grid. A room-temperature energy resolution of 6% full width at half maximum (FWHM) was obtained for the 662keV peak of Cs-137 without any additional electrical corrections. The detector's fabrication process is described, and its characteristics are discussed. Finally, the charge transport properties and gamma-ray energy resolution of the fabricated Frisch collar grid detector are compared with those of two other Frisch collar detectors grown by using different crystal growth methods and purchased from eV-products and Redlen technology.

  20. Single-crystalline Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+x} detectors for direct detection of microwave radiation

    SciTech Connect

    Li, M. Winkler, D.; Yurgens, A.

    2015-04-13

    We test radiation detectors made from single-crystalline Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+x} flakes put on oxidized Si substrates. The 100-nm-thick flakes are lithographically patterned into 4×12??m{sup 2} large rectangles embedded in thin-film log-spiral antennas. The SiO{sub 2} layer weakens the thermal link between the flakes and the bath. Two modes of radiation detection have been observed. For a bolometric type of sensors a responsivity of ?300 V/W and a noise equivalent power of 30 nW/?(Hz) has been deduced at 70?K. Much more sensitive is the non-bolometric device showing characteristics similar to a Golay-type detector while being at least a thousand times faster. Making smaller (sub-?m) structures is expected to significantly improve the performance of these devices and makes them very competitive among other microwave and terahertz detectors.

  1. Invited Review Article: Physics and Monte Carlo techniques as relevant to cryogenic, phonon, and ionization readout of Cryogenic Dark Matter Search radiation detectors

    SciTech Connect

    Leman, Steven W.

    2012-09-15

    This review discusses detector physics and Monte Carlo techniques for cryogenic, radiation detectors that utilize combined phonon and ionization readout. A general review of cryogenic phonon and charge transport is provided along with specific details of the Cryogenic Dark Matter Search detector instrumentation. In particular, this review covers quasidiffusive phonon transport, which includes phonon focusing, anharmonic decay, and isotope scattering. The interaction of phonons in the detector surface is discussed along with the downconversion of phonons in superconducting films. The charge transport physics include a mass tensor which results from the crystal band structure and is modeled with a Herring-Vogt transformation. Charge scattering processes involve the creation of Neganov-Luke phonons. Transition-edge-sensor (TES) simulations include a full electric circuit description and all thermal processes including Joule heating, cooling to the substrate, and thermal diffusion within the TES, the latter of which is necessary to model normal-superconducting phase separation. Relevant numerical constants are provided for these physical processes in germanium, silicon, aluminum, and tungsten. Random number sampling methods including inverse cumulative distribution function (CDF) and rejection techniques are reviewed. To improve the efficiency of charge transport modeling, an additional second order inverse CDF method is developed here along with an efficient barycentric coordinate sampling method of electric fields. Results are provided in a manner that is convenient for use in Monte Carlo and references are provided for validation of these models.

  2. Progress Towards High-Sensitivity Arrays of Detectors of Sub-mm Radiation using Superconducting Tunnel Junctions with Radio-Frequency Single-Electron Transistors

    NASA Technical Reports Server (NTRS)

    Stevenson, T. R.; Hsieh, W.-T.; Li, M. J.; Stahle, C. M.; Wollack, E. J.; Schoelkopf, R. J.; Krebs, Carolyn (Technical Monitor)

    2002-01-01

    The science drivers for the SPIRIT/SPECS missions demand sensitive, fast, compact, low-power, large-format detector arrays for high resolution imaging and spectroscopy in the far infrared and submillimeter. Detector arrays with 10,000 pixels and sensitivity less than 10(exp 20)-20 W/Hz(exp 20)0.5 are needed. Antenna-coupled superconducting tunnel junction detectors with integrated rf single-electron transistor readout amplifiers have the potential for achieving this high level of sensitivity, and can take advantage of an rf multiplexing technique when forming arrays. The device consists of an antenna structure to couple radiation into a small superconducting volume and cause quasiparticle excitations, and a single-electron transistor to measure currents through tunnel junction contacts to the absorber volume. We will describe optimization of device parameters, and recent results on fabrication techniques for producing devices with high yield for detector arrays. We will also present modeling of expected saturation power levels, antenna coupling, and rf multiplexing schemes.

  3. Invited review article: physics and Monte Carlo techniques as relevant to cryogenic, phonon, and ionization readout of Cryogenic Dark Matter Search radiation detectors.

    PubMed

    Leman, Steven W

    2012-09-01

    This review discusses detector physics and Monte Carlo techniques for cryogenic, radiation detectors that utilize combined phonon and ionization readout. A general review of cryogenic phonon and charge transport is provided along with specific details of the Cryogenic Dark Matter Search detector instrumentation. In particular, this review covers quasidiffusive phonon transport, which includes phonon focusing, anharmonic decay, and isotope scattering. The interaction of phonons in the detector surface is discussed along with the downconversion of phonons in superconducting films. The charge transport physics include a mass tensor which results from the crystal band structure and is modeled with a Herring-Vogt transformation. Charge scattering processes involve the creation of Neganov-Luke phonons. Transition-edge-sensor (TES) simulations include a full electric circuit description and all thermal processes including Joule heating, cooling to the substrate, and thermal diffusion within the TES, the latter of which is necessary to model normal-superconducting phase separation. Relevant numerical constants are provided for these physical processes in germanium, silicon, aluminum, and tungsten. Random number sampling methods including inverse cumulative distribution function (CDF) and rejection techniques are reviewed. To improve the efficiency of charge transport modeling, an additional second order inverse CDF method is developed here along with an efficient barycentric coordinate sampling method of electric fields. Results are provided in a manner that is convenient for use in Monte Carlo and references are provided for validation of these models. PMID:23020355

  4. Superior CT coronary angiography image quality at lower radiation exposure with second generation 320-detector row CT in patients with elevated heart rate: a comparison with first generation 320-detector row CT

    PubMed Central

    Soh, Siang Y.; Ko, Brian S. H.; Cameron, James D.; Crossett, Marcus; Nasis, Arthur; Troupis, John; Meredith, Ian T.; Seneviratne, Sujith K.

    2014-01-01

    Background This study aims to compare the image quality of second generation versus first generation 320-computed tomography coronary angiography (CTCA) in patients with heart rate ?65 bpm as it has not been specifically reported. Methods Consecutive patients who underwent CTCA using second-generation-320-detector-row-CT were prospectively enrolled. A total of 50 patients with elevated (?65 bpm) heart rate and 50 patients with controlled (<65 bpm) heart rate were included. Age and gender matched patients who were scanned with the first-generation-320-detector-row-CT were retrospectively identified. Image quality in each coronary artery segment was assessed by two blinded CT angiographers using the five-point Likert scale. Results In the elevated heart rate cohorts, while there was no significant difference in heart rate during scan-acquisition (66 vs. 69 bpm, P=0.308), or body mass index (28.5 vs. 29.6, P=0.464), the second generation scanner was associated with better image quality (3.94±0.6 vs. 3.45±0.8, P=0.001), and with lower radiation (2.8 vs. 4.3 mSv, P=0.009). There was no difference in scan image quality for the controlled heart rate cohorts. Conclusions The second generation CT scanner provides better image quality at lower radiation dose in patients with elevated heart rate (?65 bpm) compared to first generation CT scanner. PMID:25276615

  5. Characteristics of a planar-type Cd0.9Zn0.1Te radiation detector grown by using the low-pressure bridgman method

    NASA Astrophysics Data System (ADS)

    Jeong, Manhee; Kim, Han Soo; Kim, Young Soo; Ha, Jang Ho

    2014-04-01

    An indium-doped (7 ppm) Cd0.9Zn0.1Te single crystal for use in room-temperature radiation detectors has been grown using a low-pressure Bridgman (LPB) furnace at the Korea Atomic Research Institute. The single crystal has a (111) orientation and a high resistivity of ˜1 × 1012 ?·cm. In addition, the mobility-lifetime products of the electrons and hole are 4.2 × 10-4 cm2/V and 5 × 10-5 cm2/V, respectively. These values are simply derived by using a Hecht and a neural equation and 5 MeV alpha particles emitted from an 241Am alpha source. To characterize the Cd0.9Zn0.1Te grown by using the LPB method, we fabricated planar detectors with volume of 10 × 10 × 2.5 mm3 from a 2-inch-diameter Cd0.9Zn0.1Te ingot.

  6. Progress Towards High-Sensitivity Arrays of Detectors of Sub-mm Radiation Using Superconducting Tunnel Junctions with Integrated Radio Frequency Single-Electron Transistors

    NASA Technical Reports Server (NTRS)

    Stevenson, T. R.; Hsieh, W.-T.; Li, M. J.; Prober, D. E.; Rhee, K. W.; Schoelkopf, R. J.; Stahle, C. M.; Teufel, J.; Wollack, E. J.

    2004-01-01

    For high resolution imaging and spectroscopy in the FIR and submillimeter, space observatories will demand sensitive, fast, compact, low-power detector arrays with 104 pixels and sensitivity less than 10(exp -20) W/Hz(sup 0.5). Antenna-coupled superconducting tunnel junctions with integrated rf single-electron transistor readout amplifiers have the potential for achieving this high level of sensitivity, and can take advantage of an rf multiplexing technique. The device consists of an antenna to couple radiation into a small superconducting volume and cause quasiparticle excitations, and a single-electron transistor to measure current through junctions contacting the absorber. We describe optimization of device parameters, and results on fabrication techniques for producing devices with high yield for detector arrays. We also present modeling of expected saturation power levels, antenna coupling, and rf multiplexing schemes.

  7. A comparative study of the radiation hardness of plastic scintillators for the upgrade of the Tile Calorimeter of the ATLAS detector

    NASA Astrophysics Data System (ADS)

    Liao, S.; Erasmus, R.; Jivan, H.; Pelwan, C.; Peters, G.; Sideras-Haddad, E.

    2015-10-01

    The influence of radiation on the light transmittance of plastic scintillators was studied experimentally. The high optical transmittance property of plastic scintillators makes them essential in the effective functioning of the Tile calorimeter of the ATLAS detector at CERN. This significant role played by the scintillators makes this research imperative in the movement towards the upgrade of the tile calorimeter. The radiation damage of polyvinyl toluene (PVT) based plastic scintillators was studied, namely, EJ-200, EJ-208 and EJ-260, all manufactured and provided to us by ELJEN technology. In addition, in order to compare to scintillator brands actually in use at the ATLAS detector currently, two polystyrene (PS) based scintillators and an additional PVT based scintillator were also scrutinized in this study, namely, Dubna, Protvino and Bicron, respectively. All the samples were irradiated using a 6 MeV proton beam at different doses at iThemba LABS Gauteng. The radiation process was planned and mimicked by doing simulations using a SRIM program. In addition, transmission spectra for the irradiated and unirradiated samples of each grade were obtained, observed and analyzed.

  8. Organic liquid scintillation detectors for on-the-fly neutron/gamma alarming and radionuclide identification in a pedestrian radiation portal monitor

    NASA Astrophysics Data System (ADS)

    Paff, Marc Gerrit; Ruch, Marc L.; Poitrasson-Riviere, Alexis; Sagadevan, Athena; Clarke, Shaun D.; Pozzi, Sara

    2015-07-01

    We present new experimental results from a radiation portal monitor based on the use of organic liquid scintillators. The system was tested as part of a 3He-free radiation portal monitor testing campaign at the European Commission's Joint Research Centre in Ispra, Italy, in February 2014. The radiation portal monitor was subjected to a wide range of test conditions described in ANSI N42.35, including a variety of gamma-ray sources and a 20,000 n/s 252Cf source. A false alarm test tested whether radiation portal monitors ever alarmed in the presence of only natural background. The University of Michigan Detection for Nuclear Nonproliferation Group's system triggered zero false alarms in 2739 trials. It consistently alarmed on a variety of gamma-ray sources travelling at 1.2 m/s at a 70 cm source to detector distance. The neutron source was detected at speeds up to 3 m/s and in configurations with up to 8 cm of high density polyethylene shielding. The success of on-the-fly radionuclide identification varied with the gamma-ray source measured as well as with which of two radionuclide identification methods was used. Both methods used a least squares comparison between the measured pulse height distributions to library spectra to pick the best match. The methods varied in how the pulse height distributions were modified prior to the least squares comparison. Correct identification rates were as high as 100% for highly enriched uranium, but as low as 50% for 241Am. Both radionuclide identification algorithms produced mixed results, but the concept of using liquid scintillation detectors for gamma-ray and neutron alarming in radiation portal monitor was validated.

  9. Analysis of 3D silicon pixel vertex detector damage effects due to radiation levels present in the LHC at CERN

    E-print Network

    Chapa, Matthew R

    2012-01-01

    In high energy physics experiments, very high precision tracking of charged particles is needed. Solid state detectors achieve the high precision necessary to provide track and vertex reconstruction of the particles that ...

  10. Geant4 simulations of Solar-Orbiter STIX Caliste detectors’ response to solar X-ray radiation

    NASA Astrophysics Data System (ADS)

    Barylak, Jaromir; Barylak, Aleksandra; Mrozek, Tomasz; Steslicki, Marek; Podgorski, Piotr; Netzel, Henryka

    2015-08-01

    Spectrometer/Telescope for Imaging X-rays (STIX) is a part of Solar Orbiter (SO) science payload. SO which will be launched in October 2018 into final orbit approaching the Sun to within 0.3 a.u. STIX is a Fourier imager equipped with pairs of grids that comprise the flare hard X-ray tomograph. Similar imager types were already used in the past (eq. RHESSI, Yohkoh/HXT), but STIX will incorporate Moiré modulation and a new type of pixelated? detectors.We developed a method of modeling these detectors’ response matrix (DRM) using the Geant4 simulations of X-ray photons interactions with CdTe crystals. Taking into account known detector effects (Fano noise, hole tailing etc.) we modeled the resulting spectra with high accuracy. Comparison of Caliste-SO laboratory measurements of 241Am decay spectrum with our results shows a perfect agreement (within 1-2%).By using the Geant4 tool we proceed to model ageing response of detectors (several years in interplanetary space). The modeling based on the Geant4 simulations significantly improves our understanding of detector response to X-ray photons and secondary background emission due to particles. As an example we present predicted X-ray spectra of solar flares obtained for several levels of detectors’ degradation and for various distances of SO from the Sun.

  11. Characterization of high-resistivity CdTe and Cd0.9Zn0.1Te crystals grown by Bridgman method for radiation detector applications

    NASA Astrophysics Data System (ADS)

    Mandal, Krishna C.; Krishna, Ramesh M.; Pak, Rahmi O.; Mannan, Mohammad A.

    2014-09-01

    CdTe and Cd0.9Zn0.1Te (CZT) crystals have been studied extensively for various applications including x- and ?-ray imaging and high energy radiation detectors. The crystals were grown from zone refined ultra-pure precursor materials using a vertical Bridgman furnace. The growth process has been monitored, controlled, and optimized by a computer simulation and modeling program developed in our laboratory. The grown crystals were thoroughly characterized after cutting wafers from the ingots and processed by chemo-mechanical polishing (CMP). The infrared (IR) transmission images of the post-treated CdTe and CZT crystals showed average Te inclusion size of ~10 ?m for CdTe and ~8 ?m for CZT crystal. The etch pit density was ? 5×104 cm-2 for CdTe and ? 3×104 cm-2 for CZT. Various planar and Frisch collar detectors were fabricated and evaluated. From the current-voltage measurements, the electrical resistivity was estimated to be ~ 1.5×1010 ?-cm for CdTe and 2-5×1011 ?-cm for CZT. The Hecht analysis of electron and hole mobility-lifetime products (??e and ??h) showed ??e = 2×10-3 cm2/V (??h = 8×10-5 cm2/V) and 3-6×10-3 cm2/V (??h = 4- 6×10-5 cm2/V) for CdTe and CZT, respectively. Detectors in single pixel, Frisch collar, and coplanar grid geometries were fabricated. Detectors in Frisch grid and guard-ring configuration were found to exhibit energy resolution of 1.4% and 2.6 %, respectively, for 662 keV gamma rays. Assessments of the detector performance have been carried out also using 241Am (60 keV) showing energy resolution of 4.2% FWHM.

  12. Radiation dose reduction using a CdZnTe-based computed tomography system: Comparison to flat-panel detectors

    SciTech Connect

    Le, Huy Q.; Ducote, Justin L.; Molloi, Sabee

    2010-03-15

    Purpose: Although x-ray projection mammography has been very effective in early detection of breast cancer, its utility is reduced in the detection of small lesions that are occult or in dense breasts. One drawback is that the inherent superposition of parenchymal structures makes visualization of small lesions difficult. Breast computed tomography using flat-panel detectors has been developed to address this limitation by producing three-dimensional data while at the same time providing more comfort to the patients by eliminating breast compression. Flat panels are charge integrating detectors and therefore lack energy resolution capability. Recent advances in solid state semiconductor x-ray detector materials and associated electronics allow the investigation of x-ray imaging systems that use a photon counting and energy discriminating detector, which is the subject of this article. Methods: A small field-of-view computed tomography (CT) system that uses CdZnTe (CZT) photon counting detector was compared to one that uses a flat-panel detector for different imaging tasks in breast imaging. The benefits afforded by the CZT detector in the energy weighting modes were investigated. Two types of energy weighting methods were studied: Projection based and image based. Simulation and phantom studies were performed with a 2.5 cm polymethyl methacrylate (PMMA) cylinder filled with iodine and calcium contrast objects. Simulation was also performed on a 10 cm breast specimen. Results: The contrast-to-noise ratio improvements as compared to flat-panel detectors were 1.30 and 1.28 (projection based) and 1.35 and 1.25 (image based) for iodine over PMMA and hydroxylapatite over PMMA, respectively. Corresponding simulation values were 1.81 and 1.48 (projection based) and 1.85 and 1.48 (image based). Dose reductions using the CZT detector were 52.05% and 49.45% for iodine and hydroxyapatite imaging, respectively. Image-based weighting was also found to have the least beam hardening effect. Conclusions: The results showed that a CT system using an energy resolving detector reduces the dose to the patient while maintaining image quality for various breast imaging tasks.

  13. Output correction factors for nine small field detectors in 6 MV radiation therapy photon beams: A PENELOPE Monte Carlo study

    SciTech Connect

    Benmakhlouf, Hamza; Sempau, Josep; Andreo, Pedro

    2014-04-15

    Purpose: To determine detector-specific output correction factors,k{sub Q} {sub c{sub l{sub i{sub n}}}} {sub ,Q} {sub m{sub s{sub r}}} {sup f{sub {sup {sub c}{sub l}{sub i}{sub n}{sub {sup ,f{sub {sup {sub m}{sub s}{sub r}{sub ,}}}}}}}} in 6 MV small photon beams for air and liquid ionization chambers, silicon diodes, and diamond detectors from two manufacturers. Methods: Field output factors, defined according to the international formalism published byAlfonso et al. [Med. Phys. 35, 5179–5186 (2008)], relate the dosimetry of small photon beams to that of the machine-specific reference field; they include a correction to measured ratios of detector readings, conventionally used as output factors in broad beams. Output correction factors were calculated with the PENELOPE Monte Carlo (MC) system with a statistical uncertainty (type-A) of 0.15% or lower. The geometries of the detectors were coded using blueprints provided by the manufacturers, and phase-space files for field sizes between 0.5 × 0.5 cm{sup 2} and 10 × 10 cm{sup 2} from a Varian Clinac iX 6 MV linac used as sources. The output correction factors were determined scoring the absorbed dose within a detector and to a small water volume in the absence of the detector, both at a depth of 10 cm, for each small field and for the reference beam of 10 × 10 cm{sup 2}. Results: The Monte Carlo calculated output correction factors for the liquid ionization chamber and the diamond detector were within about ±1% of unity even for the smallest field sizes. Corrections were found to be significant for small air ionization chambers due to their cavity dimensions, as expected. The correction factors for silicon diodes varied with the detector type (shielded or unshielded), confirming the findings by other authors; different corrections for the detectors from the two manufacturers were obtained. The differences in the calculated factors for the various detectors were analyzed thoroughly and whenever possible the results were compared to published data, often calculated for different accelerators and using the EGSnrc MC system. The differences were used to estimate a type-B uncertainty for the correction factors. Together with the type-A uncertainty from the Monte Carlo calculations, an estimation of the combined standard uncertainty was made, assigned to the mean correction factors from various estimates. Conclusions: The present work provides a consistent and specific set of data for the output correction factors of a broad set of detectors in a Varian Clinac iX 6 MV accelerator and contributes to improving the understanding of the physics of small photon beams. The correction factors cannot in general be neglected for any detector and, as expected, their magnitude increases with decreasing field size. Due to the reduced number of clinical accelerator types currently available, it is suggested that detector output correction factors be given specifically for linac models and field sizes, rather than for a beam quality specifier that necessarily varies with the accelerator type and field size due to the different electron spot dimensions and photon collimation systems used by each accelerator model.

  14. Multipurpose Radiation Resistant Semiconductor Detectors for Alpha, Neutron & Low Energy Gamma Ray Measurements at High Temperatures in High-Intensity Gamma Ray

    SciTech Connect

    Ruddy, Frank H.

    2005-06-01

    Work scheduled under year two of DOE Grant DE-FG02-04ER63734 is on schedule and all year-two milestones have or will be met. Results to date demonstrate that unprecedented silicon carbide (SiC) energy resolution has been obtained, and that SiC detectors may achieve energy resolution that exceeds that obtainable with the best silicon alpha spectrometers. Fast-neutron energy spectrometry measurements indicate that recoil-ion energy spectrometry should be possible with SiC detectors. Furthermore, SiC detectors have been demonstrated to perform well even after gamma-ray exposures of 1.E09 Rad. This result and the previously demonstrated capability of SiC detectors to operate in elevated-temperature environments are very promising for potential DOE EMSP applications. A new class of multipurpose, radiation-resistant semiconductor detectors that can be used in elevated-temperature and high-radiation environments is being developed under this grant. These detectors, based on silicon carbide (SiC) semiconductor are designed to have larger active volumes than previously available SiC detectors, and are being tested for their response to alpha particles, X-rays and low energy gamma rays, and fast neutrons. Specifically, SiC radiation detectors with larger areas and 100-micrometer thick active regions have been designed and manufactured according to detector-design specifications. Detectors based on a Schottky diode design were specified in order to minimize the effects of the detector entrance window on alpha particle measurements. During manufacture of the Schottky diodes, the manufacturer also provided a set of large-volume SiC p-i-n diodes for testing Extensive alpha particle measurements have been carried out to test and quantify the response of the SiC Schottky diodes. Exposures to 148-Gd, 213-Po, 217-At, 221-Fr, 225-Ac, 237-Np, 238-Pu, 240-Pu, and 242-Pu sources were used to obtain detailed alpha response data in the alpha energy range from 3182.787 keV to 8375.9 keV. The 148-Gd, 213-Po, 217-At, and 221-Fr sources provide energy-separated, mono-energetic alpha particle peaks which can be analyzed to provide detailed information on the energy response characteristics of the detectors. As was reported last year, a highly linear response was obtained between observed pulse height and alpha-particle energy over the entire energy range. Detailed full width at half maximum (FWHM) measurements were made for each of five mono-energetic peaks. The FWHM values ranged from 41.5 keV for 3182.787-keV 148-Gd (1.3% energy resolution) to 55.4 keV for 8379.5-keV 213-Po (0.66% energy resolution). Although these energy resolution values are comparable to those obtainable with silicon alpha-particle spectrometers and surpass the best values reported previously for SiC detectors, other factors in addition to the inherent SiC energy resolution contribute to the observed values and were evaluated. Details of the energy deposition processes that contribute to the FWHM were modeled with calculations using the SRIM-2003.26 code developed by Ziegler and Beirsack. Electronic and statistical broadening of the FWHM were also evaluated in order to isolate the component of the FWHM that is inherent to SiC semiconductor. It was found that the SRIM calculations systematically overestimated the range straggling component of the FWHM leading to calculated values that exceeded the measured total FWHM values. It is believed that the overestimates are a result of inherent limitations of the SRIM code. The range-straggling component of the measured energy resolution results primarily from energy-loss processes in the detector entrance window, which consists of thin layers of Au, Pt, and Ti. Therefore, it was decided to perform measurements to evaluate the range straggling component directly. For this purpose, a high-resolution (15 keV FWHM) Si alpha spectrometer was obtained.

  15. Study of the radiation damage induced by high energy gamma-ray in CdTe detectors

    SciTech Connect

    Chirco, P.; Zanarini, M.; Querzola, E.

    1998-12-31

    In recent years the performance of room-temperature semiconductor detectors such as CdTe are improved and they are now suitable candidates for several applications. However, some key parameters that can severely affect such performances have not been measured yet. Thus the authors have studied the damaging of a set of CdTe detectors irradiated in a {sup 60}Co gamma-cell in a wide range of doses and dose-rates. A full characterization of the performance of irradiated detectors has been obtained by means of spectroscopic, electrostatic, photo-induced current transient spectroscopy and photo-deep level transient spectroscopy measurements to quote the energy resolution, the leakage current, the activation energy and capture cross-section of deep level defects, respectively.

  16. Quantum dosimetry and online visualization of X-ray and charged particle radiation in commercial aircraft at operational flight altitudes with the pixel detector Timepix

    NASA Astrophysics Data System (ADS)

    Granja, Carlos; Pospisil, Stanislav

    2014-07-01

    We investigate the application of the hybrid semiconductor pixel detector Timepix for precise characterization, quantum sensitivity dosimetry and visualization of the charged particle radiation and X-ray field inside commercial aircraft at operational flight altitudes. The quantum counting capability and granularity of Timepix provides the composition and spectral-characteristics of the X-ray and charged-particle field with high sensitivity, wide dynamic range, high spatial resolution and particle type resolving power. For energetic charged particles the direction of trajectory and linear energy transfer can be measured. The detector is operated by the integrated readout interface FITPix for power, control and data acquisition together with the software package Pixelman for online visualization and real-time data processing. The compact and portable radiation camera can be deployed remotely being controlled simply by a laptop computer. The device performs continuous monitoring and accurate time-dependent measurements in wide dynamic range of particle fluxes, deposited energy, absorbed dose and equivalent dose rates. Results are presented for in-flight measurements at altitudes up to 12 km in various flights selected in the period 2006-2013.

  17. Optimal optoacoustic detector design

    NASA Technical Reports Server (NTRS)

    Rosengren, L.-G.

    1975-01-01

    Optoacoustic detectors are used to measure pressure changes occurring in enclosed gases, liquids, or solids being excited by intensity or frequency modulated electromagnetic radiation. Radiation absorption spectra, collisional relaxation rates, substance compositions, and reactions can be determined from the time behavior of these pressure changes. Very successful measurements of gaseous air pollutants have, for instance, been performed by using detectors of this type together with different lasers. The measuring instrument consisting of radiation source, modulator, optoacoustic detector, etc. is often called spectrophone. In the present paper, a thorough optoacoustic detector optimization analysis based upon a review of its theory of operation is introduced. New quantitative rules and suggestions explaining how to design detectors with maximal pressure responsivity and over-all sensitivity and minimal background signal are presented.

  18. Radiation

    Cancer.gov

    DCEG researchers carry out a broad-based research program designed to identify, understand, and quantify the risk of cancer in populations exposed to medical, occupational, or environmental radiation. They study ionizing radiation exposures (e.g., x-rays,

  19. Arsenic activation neutron detector

    DOEpatents

    Jacobs, Eddy L. (Albuquerque, NM)

    1981-01-01

    A detector of bursts of neutrons from a deuterium-deuteron reaction includes a quantity of arsenic adjacent a gamma detector such as a scintillator and photomultiplier tube. The arsenic is activated by the 2.5 Mev neutrons to release gamma radiation which is detected to give a quantitative representation of detected neutrons.

  20. Arsenic activation neutron detector

    DOEpatents

    Jacobs, E.L.

    1980-01-28

    A detector of bursts of neutrons from a deuterium-deuteron reaction includes a quantity of arsenic adjacent a gamma detector such as a scintillator and photomultiplier tube. The arsenic is activated by the 2.5-MeV neutrons to release gamma radiation which is detected to give a quantitative representation of detected neutrons.

  1. Influence of the gamma-ray fraction in the reactor radiation on the total signal of a self-powered neutron detector

    NASA Astrophysics Data System (ADS)

    Kurchenkov, A. Yu.; Kulakov, A. S.; Alekseev, N. I.; Kalinushkin, A. E.

    2013-12-01

    For controlling the linear power density in the reactor core, the Khortitsa-M software program as a part of the in-core instrumentation system (ICIS) employs only self-powered neutron detector (SPND) data with the neutronic calculation for the consistent determination of the power density in unmeasurable fuel assemblies (FAs). The confidence of the interpretation of the SPND data essentially determines the safe and efficient operation of a reactor. Previously, it was assumed that the gamma-ray fraction in the reactor radiation does not exceed one percent and is independent of the fuel enrichment and the FA and SPND burnups. Since it is difficult to estimate the contribution of the reactor gamma radiation to the SPND current experimentally, in this work, we present a calculated estimate using modern software and libraries of constants. On the basis of the results of this study, the question is discussed whether it is appropriate to take into account the reactor gamma radiation in the transfer function from the SPND current to the power density of six fuel elements surrounding the SPND with allowance for both the type of FA and the FA and SPND burnups.

  2. Cadmium Manganese Telluride (Cd1-xMnxTe): A potential material for room-temperature radiation detectors

    SciTech Connect

    Hossain, A.; Cui, Y.; Bolotnikov, A.; Camarda, G.; Yang, G.; Kim, K-H.; Gul, R.; Xu, L.; Li, L.; Mycielski, A.; and James, R.B.

    2010-07-11

    Cadmium Manganese Telluride (CdMnTe) recently emerged as a promising material for room-temperature X- and gamma-ray detectors. It offers several potential advantages over CdZnTe. Among them is its optimal tunable band gap ranging from 1.7-2.2 eV, and its relatively low (< 50%) content of Mn compared to that of Zn in CdZnTe that assures this favorable band-gap range. Another important asset is the segregation coefficient of Mn in CdTe that is approximately unity compared to 1.35 for Zn in CdZnTe, so ensuring the homogenous distribution of Mn throughout the ingot; hence, a large-volume stoichiometric yield is attained. However, some materials issues primarily related to the growth process impede the production of large, defect-free single crystals. The high bond-ionicity of CdMnTe entails a higher propensity to crystallize into a hexagonal structure rather than to adopt the expected zinc-blend structure, which is likely to generate twins in the crystals. In addition, bulk defects generate in the as-grown crystals due to the dearth of high-purity Mn, which yields a low-resistivity material. In this presentation, we report on our observations of such material defects in current CdMnTe materials, and our evaluation of its potential as an alternative detector material to the well-known CdZnTe detectors. We characterized the bulk defects of several indium- and vanadium-doped Cd1-xMnxTe crystals by using several advanced techniques, viz., micro-scale mapping, white-beam x-ray diffraction/reflection topography, and chemical etching. Thereafter, we fabricated some detectors from selected CdMnTe crystals, characterized their electrical properties, and tested their performance as room-temperature X- and gamma-ray detectors. Our experimental results indicate that CdMnTe materials could well prove to become a viable alternative in the near future.

  3. New electronically black neutron detectors

    SciTech Connect

    Drake, D.M.; Feldman, W.C.; Hurlbut, C.

    1986-03-01

    Two neutron detectors are described that can function in a continuous radiation background. Both detectors identify neutrons by recording a proton recoil pulse followed by a characteristic capture pulse. This peculiar signature indicates that the neutron has lost all its energy in the scintillator. Resolutions and efficiencies have been measured for both detectors.

  4. Charge-carrier mobilities in Cd(0.8)Zn(0.2)Te single crystals used as nuclear radiation detectors

    NASA Technical Reports Server (NTRS)

    Burshtein, Z.; Jayatirtha, H. N.; Burger, A.; Butler, J. F.; Apotovsky, B.; Doty, F. P.

    1993-01-01

    Charge-carrier mobilities were measured for the first time in Cd(0.8)Zn(0.2)Te single crystals using time-of-flight measurements of charge carriers produced by short (10 ns) light pulses from a frequency-doubled Nd:YAG laser (532 nm). The electron mobility displayed a T exp -1.1 dependence on the absolute temperature T in the range 200-320 K, with a room-temperature mobility of 1350 sq cm/V s. The hole mobility displayed a T exp -2.0 dependence in the same temperature range, with a room-temperature mobility of 120 sq cm/V s. Cd(0.8)Zn(0.2)Te appears to be a very favorable material for a room-temperature electronic nuclear radiation detector.

  5. The CDFII Silicon Detector

    SciTech Connect

    Julia Thom

    2004-07-23

    The CDFII silicon detector consists of 8 layers of double-sided silicon micro-strip sensors totaling 722,432 readout channels, making it one of the largest silicon detectors in present use by an HEP experiment. After two years of data taking, we report on our experience operating the complex device. The performance of the CDFII silicon detector is presented and its impact on physics analyses is discussed. We have already observed measurable effects from radiation damage. These results and their impact on the expected lifetime of the detector are briefly reviewed.

  6. Micro-channel plate detector

    SciTech Connect

    Elam, Jeffrey W.; Lee, Seon W.; Wang, Hsien -Hau; Pellin, Michael J.; Byrum, Karen; Frisch, Henry J.

    2015-09-22

    A method and system for providing a micro-channel plate detector. An anodized aluminum oxide membrane is provided and includes a plurality of nanopores which have an Al coating and a thin layer of an emissive oxide material responsive to incident radiation, thereby providing a plurality of radiation sensitive channels for the micro-channel plate detector.

  7. Directional gamma detector

    DOEpatents

    LeVert, Francis E. (Downers Grove, Knoxville, TN); Cox, Samson A. (Downers Grove, IL)

    1981-01-01

    An improved directional gamma radiation detector has a collector sandwiched etween two layers of insulation of varying thicknesses. The collector and insulation layers are contained within an evacuated casing, or emitter, which releases electrons upon exposure to gamma radiation. Delayed electrons and electrons entering the collector at oblique angles are attenuated as they pass through the insulation layers on route to the collector.

  8. First studies of electron transport along small gas gaps of novel foil radiation converters for fast-neutron detectors

    NASA Astrophysics Data System (ADS)

    Cortesi, M.; Zboray, R.; Adams, R.; Dangendorf, V.; Breskin, A.; Mayer, S.; Hoedlmoser, H.; Prasser, H.-M.

    2013-01-01

    Novel high-efficiency fast-neutron detectors were suggested for fan-beam tomography applications. They combine multi-layer polymer converters in gas medium, coupled to thick gaseous electron multipliers (THGEM). Neutron-induced scattering on the converter's hydrogen nuclei results in gas ionization by the escaping recoil-protons between two successive converters. The electrons drift under the action of a homogeneous electric field, parallel to the converter-foil surfaces, towards a position-sensitive THGEM multiplying element. In this work we discuss the results of a systematic study of the electron transport inside a narrow gap between successive converter foils, which affects the performance of the detector, both in terms of detection efficiency and localization properties. The efficiency of transporting ionization electrons was measured along a 0.6 mm wide gas gap in 6 and 10 mm wide polymer converters. Computer simulations provided conceptual understanding of the observations. For drift lengths of 6 mm, electrons were efficiently transported along the narrow gas gap with minimal diffusion-induced losses; an average collection efficiency of 95% was achieved for ionization electrons induced by few keV photoelectrons. The 10 mm height converter yielded considerably lower efficiency due to electrical and mechanical flaws of the converter foils. The results indicate that detection efficiencies of ~ 7% can be expected for 2.5 MeV neutrons with 300-foils converters, of 6 mm height, 0.4 mm thick foils and 0.6 mm gas gap.

  9. Semiconductor neutron detector

    DOEpatents

    Ianakiev, Kiril D. (Los Alamos, NM); Littlewood, Peter B. (Cambridge, GB); Blagoev, Krastan B. (Arlington, VA); Swinhoe, Martyn T. (Los Alamos, NM); Smith, James L. (Los Alamos, NM); Sullivan, Clair J. (Los Alamos, NM); Alexandrov, Boian S. (Los Alamos, NM); Lashley, Jason Charles (Santa Fe, NM)

    2011-03-08

    A neutron detector has a compound of lithium in a single crystal form as a neutron sensor element. The lithium compound, containing improved charge transport properties, is either lithium niobate or lithium tantalate. The sensor element is in direct contact with a monitor that detects an electric current. A signal proportional to the electric current is produced and is calibrated to indicate the neutrons sensed. The neutron detector is particularly useful for detecting neutrons in a radiation environment. Such radiation environment may, e.g. include gamma radiation and noise.

  10. The DØ detector

    NASA Astrophysics Data System (ADS)

    Abachi, S.; Abolins, M.; Acharya, B. S.; Adam, I.; Ahn, S.; Aihara, H.; Alvarez, G.; Alves, G. A.; Amos, N.; Anderson, W.; Antipov, Yu.; Aronson, S. H.; Astur, R.; Avery, R. E.; Baden, A.; Balderston, J.; Baldin, B.; Bantly, J.; Barasch, E.; Bartlett, J. F.; Bazizi, K.; Behnke, T.; Bezzubov, V.; Bhat, P. C.; Blazey, G.; Blessing, S.; Boehnlein, A.; Borcherding, F.; Borders, J.; Bozko, N.; Brandt, A.; Brock, R.; Bross, A.; Buchholz, D.; Burtovoy, V.; Butler, J. M.; Callot, O.; Chakraborty, D.; Chekulaev, S.; Chen, J.; Chen, L.-P.; Chen, W.; Choudhary, B. C.; Christenson, J. H.; Claes, D.; Clark, A. R.; Cobau, W. G.; Cochran, J.; Cooper, W. E.; Cretsinger, C.; Cullen-Vidal, D.; Cummings, M.; Cutts, D.; Dahl, O. I.; Daniels, B.; De, K.; Demarteau, M.; Denisenko, K.; Denisenko, N.; Denisov, D.; Denisov, S.; Dharmaratna, W.; Diehl, H. T.; Diesburg, M.; Dixon, R.; Draper, P.; Ducros, Y.; Durston-Johnson, S.; Eartly, D.; Eberhard, P. H.; Edmunds, D.; Efimov, A.; Ellison, J.; Elvira, V. D.; Engelmann, R.; Eroshin, O.; Evdokimov, V.; Fahey, S.; Fanourakis, G.; Fatyga, M.; Featherly, J.; Feher, S.; Fein, D.; Ferbel, T.; Finley, D.; Finocchiaro, G.; Fisk, H. E.; Flattum, E.; Forden, G. E.; Fortner, M.; Franzini, P.; Fuess, S.; Gallas, E.; Gao, C. S.; Geld, T. L.; Genser, K.; Gerber, C. E.; Gibbard, B.; Glebov, V.; Glicenstein, J. F.; Gobbi, B.; Goforth, M.; Good, M. L.; Goozen, F.; Gordon, H.; Graf, N.; Grannis, P. D.; Green, D. R.; Green, J.; Greenlee, H.; Grossman, N.; Grudberg, P.; Guida, J. A.; Guida, J. M.; Guryn, W.; Hadley, N. J.; Haggerty, H.; Hagopian, S.; Hagopian, V.; Hall, R. E.; Hansen, S.; Hauptman, J.; Hedin, D.; Heinson, A. P.; Heintz, U.; Heuring, T.; Hirosky, R.; Hodel, K.; Hoftun, J. S.; Hubbard, J. R.; Huehn, T.; Huson, R.; Igarashi, S.; Ito, A. S.; James, E.; Jiang, J.; Johns, K.; Johnson, C. R.; Johnson, M.; Jonckheere, A.; Jones, M.; Jöstlein, H.; Jung, C. K.; Kahn, S.; Kanekal, S.; Kernan, A.; Kerth, L.; Kirunin, A.; Klatchko, A.; Klima, B.; Klochkov, B.; Klopfenstein, C.; Klyukhin, V.; Kochetkov, V.; Kohli, J. M.; Kononenko, W.; Kotcher, J.; Kotov, I.; Kourlas, J.; Kozelov, A.; Kozlovsky, E.; Krafczyk, G.; Krempetz, K.; Krishnaswamy, M. R.; Kroon, P.; Krzywdzinski, S.; Kunori, S.; Lami, S.; Landsberg, G.; Lanou, R. E.; Laurens, P.; Lee-Franzini, J.; Li, J.; Li, R.; Li-Demarteau, Q. Z.; Lima, J. G. R.; Linn, S. L.; Linnemann, J.; Lipton, R.; Liu, Y.-C.; Lloyd-Owen, D.; Lobkowicz, F.; Loken, S. C.; Lokos, S.; Lueking, L.; Maciel, A. K. A.; Madaras, R. J.; Madden, R.; Malamud, E.; Mangeot, Ph.; Manning, I.; Mansoulié, B.; Manzella, V.; Mao, H.-S.; Marcin, M.; Markosky, L.; Marshall, T.; Martin, H. J.; Martin, M. I.; Martin, P. S.; Marx, M.; May, B.; Mayorov, A.; McCarthy, R.; McKinley, J.; Mendoza, D.; Meng, X.-C.; Merritt, K. W.; Milder, A.; Mincer, A.; Mondal, N. K.; Montag, M.; Mooney, P.; Mudan, M.; Mulholland, G. T.; Murphy, C.; Murphy, C. T.; Nang, F.; Narain, M.; Narasimham, V. S.; Neal, H. A.; Nemethy, P.; Neši?, D.; Ng, K. K.; Norman, D.; Oesch, L.; Oguri, V.; Oltman, E.; Oshima, N.; Owen, D.; Pang, M.; Para, A.; Park, C. H.; Partridge, R.; Paterno, M.; Peryshkin, A.; Peters, M.; Pi, B.; Piekarz, H.; Pischalnikov, Yu.; Pizzuto, D.; Pluquet, A.; Podstavkov, V.; Pope, B. G.; Prosper, H. B.; Protopopescu, S.; Que, Y.-K.; Quintas, P. Z.; Rahal-Callot, G.; Raja, R.; Rajagopalan, S.; Rao, M. V. S.; Rasmussen, L.; Read, A. L.; Regan, T.; Repond, S.; Riadovikov, V.; Rijssenbeek, M.; Roe, N. A.; Rubinov, P.; Rutherfoord, J.; Santoro, A.; Sawyer, L.; Schamberger, R. D.; Sculli, J.; Selove, W.; Shea, M.; Shkurenkov, A.; Shupe, M.; Singh, J. B.; Sirotenko, V.; Smart, W.; Smith, A.; Smith, D.; Smith, R. P.; Snow, G. R.; Snyder, S.; Sosebee, M.; Souza, M.; Spadafora, A. L.; Stampke, S.; Stephens, R.; Stevenson, M. L.; Stewart, D.; Stocker, F.; Stoyanova, D.; Stredde, H.; Streets, K.; Strovink, M.; Suhanov, A.; Taketani, A.; Tartaglia, M.; Taylor, J. D.; Teiger, J.; Theodosiou, G.; Thompson, J.; Tisserant, S.; Trippe, T. G.; Tuts, P. M.; Van Berg, R.; Vaz, M.; Vishwanath, P. R.; Volkov, A.; Vorobiev, A.; Wahl, H. D.; Wang, D.-C.; Wang, L.-Z.; Weerts, H.; Wenzel, W. A.; White, A.; White, J. T.; Wightman, J.; Willis, S.; Wimpenny, S. J.; Wolf, Z.; Womersley, J.; Wood, D. R.; Xia, Y.; Xiao, D.; Xie, P.; Xu, H.; Yamada, R.; Yamin, P.; Yanagisawa, C.; Yang, J.; Yang, M.-J.; Yoshikawa, C.; Youssef, S.; Yu, J.; Zeller, R.; Zhang, S.; Zhou, Y. H.; Zhu, Q.; Zhu, Y.-S.; Zieminska, D.; Zieminski, A.; Zinchenko, A.; Zylberstejn, A.; DØ Collaboration

    1994-01-01

    The DØ detector is a large general purpose detector for the study of short-distance phenomena in high energy antiproton-proton collisions, now in operation at the Fermilab Tevatron collider. The detector focusses upon the detection of electrons, muons, jets and missing transverse momentum. We describe the design and performance of the major elements of the detector, including the tracking chambers, transition radiation detector, liquid argon calorimetry and muon detection. The associated electronics, triggering systems and data acquisition systems are presented. The global mechanical, high voltage, and experiment monitoring and control systems which support the detector are described. We also discuss the design and implementation of software and software support systems that are specific to DØ.

  11. Role of cardiac ultrafast cameras with CZT solid-state detectors and software developments on radiation absorbed dose reduction to the patients.

    PubMed

    Gunalp, Bengul

    2015-07-01

    Myocardial perfusion imaging (MPI) is one the most contributing nuclear medicine technique to the annual population dose. The purpose of this study is to compare radiation-absorbed doses to the patients examined by conventional cardiac SPECT (CSPECT) camera and ultrafast cardiac (UFC) camera with cadmium-zinc-telluride (CZT) solid-state detectors. Total injected activity was reduced by 50 % when both stress and rest images were acquired and by 75 % when only stress images were taken with UFC camera. As a result of this, the mean total effective dose was found significantly lower with UFC camera (2.2 ± 1.2 mSv) than CSPECT (7.7 ± 3.8 mSv) (p < 0.001). Further dose reduction was obtained by reducing equivocal test results and unnecessary additional examinations with UFC camera. Using UFC camera, MPI can be conveniently used for the detection of coronary artery disease (CAD) much less increasing annual population radiation dose as it had been before. PMID:25848109

  12. Sensitive semiconductor detectors of terahertz radiation for spaceborne applications based on Pb1-xSnxTe(In)

    NASA Astrophysics Data System (ADS)

    Dolzhenko, D. E.; Nicorici, A. V.; Ryabova, L. I.; Khokhlov, D. R.

    2012-09-01

    Doping of the lead telluride and related alloys with the group III impurities results in appearance of the unique physical features of a material, such as persistent photoresponse, enhanced responsive quantum efficiency (up to 100 photoelectrons/incident photon), radiation hardness and many others. We present the physical principles of operation of the photodetecting devices based on the group III-doped IV-VI including the possibilities of a fast quenching of the persistent photoresponse, construction of the focal-plane array, new readout technique, and others. The advantages of infrared photodetecting systems based on the group III-doped IV-VI in comparison with the modern photodetectors are summarized. The spectra of the persistent photoresponse have not been measured so far because of the difficulties with screening the background radiation. We report on the observation of strong persistent photoconductivity in Pb0.75Sn0.25Te(In) under the action of monochromatic submillimeter radiation at wavelengths of 176 and 241 microns. The sample temperature was 4.2 K, the background radiation was completely screened out. The sample was initially in the semiinsulating state providing dark resistance of more than 100 GOhm. The responsivity of the photodetector is by several orders of magnitude higher than in the state of the art Ge(Ga). The red cut-off wavelength exceeds the upper limit of 220 microns observed so far for the quantum photodetectors in the uniaxially stressed Ge(Ga). It is possible that the photoconductivity spectrum of Pb1-xSnxTe(In)covers all the submillimeter wavelength range.

  13. Analytical formulae to calculate the solid angle subtended at an arbitrarily positioned point source by an elliptical radiation detector

    NASA Astrophysics Data System (ADS)

    Abbas, Mahmoud I.; Hammoud, Sami; Ibrahim, Tarek; Sakr, Mohamed

    2015-01-01

    In this article, we introduce a direct analytical mathematical method for calculating the solid angle, ?, subtended at a point by closed elliptical contours. The solid angle is required in many areas of optical and nuclear physics to estimate the flux of particle beam of radiation and to determine the activity of a radioactive source. The validity of the derived analytical expressions was successfully confirmed by the comparison with some published data (Numerical Method).

  14. Thermodynamic-temperature determinations of the Ag and Au freezing temperatures using a detector-based radiation thermometer

    SciTech Connect

    Yoon, Howard W.; Allen, David W.; Gibson, Charles E.; Litorja, Maritoni; Saunders, Robert D.; Brown, Steven W.; Eppeldauer, George P.; Lykke, Keith R

    2007-05-20

    The development of a radiation thermometer calibrated for spectral radiance responsivity using cryogenic, electrical-substitution radiometry to determine the thermodynamic temperatures of the Ag- and Au-freezing temperatures is described. The absolute spectral radiance responsivity of the radiation thermometer is measured in the NIST Spectral Irradiance and Radiance Responsivity Calibrations using Uniform Sources (SIRCUS) facility with a total uncertainty of0.15% (k=2) and is traceable to the electrical watt, and thus the thermodynamic temperature of any blackbody can be determined by using Planck radiation law and the measured optical power. The thermodynamic temperatures of the Ag- and Au-freezing temperatures are determined to be1234.956 K ({+-}0.110 K) (k=2) and1337.344 K({+-}0.129 K) (k=2) differing from the International Temperature Scale of 1990 (ITS-90) assignments by 26 mK and 14 mK, respectively,within the stated uncertainties. The temperatures were systematically corrected for the size-of-source effect, the nonlinearity of the preamplifier and the emissivity of the blackbody.The ultimate goal of these thermodynamic temperature measurements is to disseminate temperature scales with lower uncertainties than those of the ITS-90. These results indicate that direct disseminations of thermodynamic temperature scales are possible.

  15. Web-based, GPU-accelerated, Monte Carlo simulation and visualization of indirect radiation imaging detector performance

    SciTech Connect

    Dong, Han; Sharma, Diksha; Badano, Aldo

    2014-12-15

    Purpose: Monte Carlo simulations play a vital role in the understanding of the fundamental limitations, design, and optimization of existing and emerging medical imaging systems. Efforts in this area have resulted in the development of a wide variety of open-source software packages. One such package, hybridMANTIS, uses a novel hybrid concept to model indirect scintillator detectors by balancing the computational load using dual CPU and graphics processing unit (GPU) processors, obtaining computational efficiency with reasonable accuracy. In this work, the authors describe two open-source visualization interfaces, webMANTIS and visualMANTIS to facilitate the setup of computational experiments via hybridMANTIS. Methods: The visualization tools visualMANTIS and webMANTIS enable the user to control simulation properties through a user interface. In the case of webMANTIS, control via a web browser allows access through mobile devices such as smartphones or tablets. webMANTIS acts as a server back-end and communicates with an NVIDIA GPU computing cluster that can support multiuser environments where users can execute different experiments in parallel. Results: The output consists of point response and pulse-height spectrum, and optical transport statistics generated by hybridMANTIS. The users can download the output images and statistics through a zip file for future reference. In addition, webMANTIS provides a visualization window that displays a few selected optical photon path as they get transported through the detector columns and allows the user to trace the history of the optical photons. Conclusions: The visualization tools visualMANTIS and webMANTIS provide features such as on the fly generation of pulse-height spectra and response functions for microcolumnar x-ray imagers while allowing users to save simulation parameters and results from prior experiments. The graphical interfaces simplify the simulation setup and allow the user to go directly from specifying input parameters to receiving visual feedback for the model predictions.

  16. Patient radiation dose in prospectively gated axial CT coronary angiography and retrospectively gated helical technique with a 320-detector row CT scanner

    SciTech Connect

    Seguchi, Shigenobu; Aoyama, Takahiko; Koyama, Shuji; Fujii, Keisuke; Yamauchi-Kawaura, Chiyo

    2010-11-15

    Purpose: The aim of this study was to evaluate radiation dose to patients undergoing computed tomography coronary angiography (CTCA) for prospectively gated axial (PGA) technique and retrospectively gated helical (RGH) technique. Methods: Radiation doses were measured for a 320-detector row CT scanner (Toshiba Aquilion ONE) using small sized silicon-photodiode dosimeters, which were implanted at various tissue and organ positions within an anthropomorphic phantom for a standard Japanese adult male. Output signals from photodiode dosimeters were read out on a personal computer, from which organ and effective doses were computed according to guidelines published in the International Commission on Radiological Protection Publication 103. Results: Organs that received high doses were breast, followed by lung, esophagus, and liver. Breast doses obtained with PGA technique and a phase window width of 16% at a simulated heart rate of 60 beats per minute were 13 mGy compared to 53 mGy with RGH technique using electrocardiographically dependent dose modulation at the same phase window width as that in PGA technique. Effective doses obtained in this case were 4.7 and 20 mSv for the PGA and RGH techniques, respectively. Conversion factors of dose length product to the effective dose in PGA and RGH were 0.022 and 0.025 mSv mGy{sup -1} cm{sup -1} with a scan length of 140 mm. Conclusions: CTCA performed with PGA technique provided a substantial effective dose reduction, i.e., 70%-76%, compared to RGH technique using the dose modulation at the same phase windows as those in PGA technique. Though radiation doses in CTCA with RGH technique were the same level as, or some higher than, those in conventional coronary angiography (CCA), the use of PGA technique reduced organ and effective doses to levels less than CCA except for breast dose.

  17. Note: Real time optical sensing of alpha-radiation emitting radioactive aerosols based on solid state nuclear track detector.

    PubMed

    Kulkarni, A; Ha, S; Joshirao, P; Manchanda, V; Bak, M S; Kim, T

    2015-06-01

    A sensitive radioactive aerosols sensor has been designed and developed. Its design guidance is based on the need for a low operational cost and reliable measurements to provide daily aerosol monitoring. The exposure of diethylene-glycol bis (allylcarbonate) to radiation causes modification of its physico-chemical properties like surface roughness and reflectance. In the present study, optical sensor based on the reflectance measurement has been developed with an aim to monitor real time presence of alpha radioactive aerosols emitted from thorium nitrate hydrate. The results shows that the fabricated sensor can detect 0.0157 kBq to 0.1572 kBq of radio activity by radioactive aerosols generated from (Th(NO3)4 ? 5H2O) at 0.1 ml/min flow rate. The proposed instrument will be helpful to monitor radioactive aerosols in/around a nuclear facility, building construction sites, mines, and granite polishing factories. PMID:26133876

  18. Note: Real time optical sensing of alpha-radiation emitting radioactive aerosols based on solid state nuclear track detector

    SciTech Connect

    Kulkarni, A.; Bak, M. S. E-mail: moonsoo@skku.edu; Ha, S.; Joshirao, P.; Manchanda, V.; Kim, T. E-mail: moonsoo@skku.edu

    2015-06-15

    A sensitive radioactive aerosols sensor has been designed and developed. Its design guidance is based on the need for a low operational cost and reliable measurements to provide daily aerosol monitoring. The exposure of diethylene-glycol bis (allylcarbonate) to radiation causes modification of its physico-chemical properties like surface roughness and reflectance. In the present study, optical sensor based on the reflectance measurement has been developed with an aim to monitor real time presence of alpha radioactive aerosols emitted from thorium nitrate hydrate. The results shows that the fabricated sensor can detect 0.0157 kBq to 0.1572 kBq of radio activity by radioactive aerosols generated from (Th(NO{sub 3}){sub 4} ? 5H{sub 2}O) at 0.1 ml/min flow rate. The proposed instrument will be helpful to monitor radioactive aerosols in/around a nuclear facility, building construction sites, mines, and granite polishing factories.

  19. Note: Real time optical sensing of alpha-radiation emitting radioactive aerosols based on solid state nuclear track detector

    NASA Astrophysics Data System (ADS)

    Kulkarni, A.; Ha, S.; Joshirao, P.; Manchanda, V.; Bak, M. S.; Kim, T.

    2015-06-01

    A sensitive radioactive aerosols sensor has been designed and developed. Its design guidance is based on the need for a low operational cost and reliable measurements to provide daily aerosol monitoring. The exposure of diethylene-glycol bis (allylcarbonate) to radiation causes modification of its physico-chemical properties like surface roughness and reflectance. In the present study, optical sensor based on the reflectance measurement has been developed with an aim to monitor real time presence of alpha radioactive aerosols emitted from thorium nitrate hydrate. The results shows that the fabricated sensor can detect 0.0157 kBq to 0.1572 kBq of radio activity by radioactive aerosols generated from (Th(NO3)4 ? 5H2O) at 0.1 ml/min flow rate. The proposed instrument will be helpful to monitor radioactive aerosols in/around a nuclear facility, building construction sites, mines, and granite polishing factories.

  20. Radiation Exposure in Biliary Procedures Performed to Manage Anastomotic Strictures in Pediatric Liver Transplant Recipients: Comparison Between Radiation Exposure Levels Using an Image Intensifier and a Flat-Panel Detector-Based System

    SciTech Connect

    Miraglia, Roberto Maruzzelli, Luigi; Tuzzolino, Fabio; Indovina, Pietro Luigi; Luca, Angelo

    2013-12-15

    Purpose: The aim of this study was to estimate radiation exposure in pediatric liver transplants recipients who underwent biliary interventional procedures and to compare radiation exposure levels between biliary interventional procedures performed using an image intensifier-based angiographic system (IIDS) and a flat panel detector-based interventional system (FPDS). Materials and Methods: We enrolled 34 consecutive pediatric liver transplant recipients with biliary strictures between January 2008 and March 2013 with a total of 170 image-guided procedures. The dose-area product (DAP) and fluoroscopy time was recorded for each procedure. The mean age was 61 months (range 4-192), and mean weight was 17 kg (range 4-41). The procedures were classified into three categories: percutaneous transhepatic cholangiography and biliary catheter placement (n = 40); cholangiography and balloon dilatation (n = 55); and cholangiography and biliary catheter change or removal (n = 75). Ninety-two procedures were performed using an IIDS. Seventy-eight procedures performed after July 2010 were performed using an FPDS. The difference in DAP between the two angiographic systems was compared using Wilcoxon rank-sum test and a multiple linear regression model. Results: Mean DAP in the three categories was significantly greater in the group of procedures performed using the IIDS compared with those performed using the FPDS. Statistical analysis showed a p value = 0.001 for the PTBD group, p = 0.0002 for the cholangiogram and balloon dilatation group, and p = 0.00001 for the group with cholangiogram and biliary catheter change or removal. Conclusion: In our selected cohort of patients, the use of an FPDS decreases radiation exposure.

  1. History of infrared detectors

    NASA Astrophysics Data System (ADS)

    Rogalski, A.

    2012-09-01

    This paper overviews the history of infrared detector materials starting with Herschel's experiment with thermometer on February 11th, 1800. Infrared detectors are in general used to detect, image, and measure patterns of the thermal heat radiation which all objects emit. At the beginning, their development was connected with thermal detectors, such as thermocouples and bolometers, which are still used today and which are generally sensitive to all infrared wavelengths and operate at room temperature. The second kind of detectors, called the photon detectors, was mainly developed during the 20th Century to improve sensitivity and response time. These detectors have been extensively developed since the 1940's. Lead sulphide (PbS) was the first practical IR detector with sensitivity to infrared wavelengths up to ˜3 ?m. After World War II infrared detector technology development was and continues to be primarily driven by military applications. Discovery of variable band gap HgCdTe ternary alloy by Lawson and co-workers in 1959 opened a new area in IR detector technology and has provided an unprecedented degree of freedom in infrared detector design. Many of these advances were transferred to IR astronomy from Departments of Defence research. Later on civilian applications of infrared technology are frequently called "dual-use technology applications." One should point out the growing utilisation of IR technologies in the civilian sphere based on the use of new materials and technologies, as well as the noticeable price decrease in these high cost technologies. In the last four decades different types of detectors are combined with electronic readouts to make detector focal plane arrays (FPAs). Development in FPA technology has revolutionized infrared imaging. Progress in integrated circuit design and fabrication techniques has resulted in continued rapid growth in the size and performance of these solid state arrays.

  2. Dark Current Characteristics of a Radiation Detector Array Developed Using MOVPE-Grown Thick CdTe Layers on Si Substrate

    NASA Astrophysics Data System (ADS)

    Yasuda, K.; Niraula, M.; Fujimura, N.; Tachi, T.; Inuzuka, H.; Namba, S.; Muramatsu, S.; Kondo, T.; Agata, Y.

    2012-10-01

    We present reverse bias current (dark current) characteristics of a two-dimensional monolithic pixel-type nuclear radiation detector array fabricated using metalorganic vapor-phase epitaxy (MOVPE)-grown thick CdTe epitaxial layers on Si substrate. The (14 × 8) pixel array was formed by cutting deep vertical trenches using a dicing saw, where each pixel possesses a p-CdTe/ n-CdTe/ n +-Si heterojunction diode structure. The dark currents showed pixel-to-pixel variations when measured at higher applied biases exceeding 100 V. The dark current had a dependence on the pixel thickness, where pixels with lower CdTe thickness exhibited higher currents. Moreover, the temperature dependence of the dark current revealed that a deep level with activation energy of around 0.6 eV is responsible for the observed dark currents and their pixel-to-pixel variation. We discuss that the effective ratio of Te to Cd at the growth surface is a major factor that controls the thickness variation, and is also responsible for the formation of 0.6 eV deep levels.

  3. Charge transport properties of p-CdTe/n-CdTe/n+-Si diode-type nuclear radiation detectors based on metalorganic vapor-phase epitaxy-grown epilayers

    NASA Astrophysics Data System (ADS)

    Niraula, M.; Yasuda, K.; Wajima, Y.; Yamashita, H.; Tsukamoto, Y.; Suzuki, Y.; Matsumoto, M.; Takai, N.; Tsukamoto, Y.; Agata, Y.

    2013-10-01

    Charge transport properties of p-CdTe/n-CdTe/n+-Si diode-type nuclear radiation detectors, fabricated by growing p-and n-type CdTe epilayers on (211) n+-Si substrates using metalorganic vapor-phase epitaxy (MOVPE), were studied by analyzing current-voltage characteristics measured at various temperatures. The diode fabricated shows good rectification properties, however, both forward and reverse biased currents deviate from their ideal behavior. The forward current exhibits typical feature of multi-step tunneling at lower biases; however, becomes space charge limited type when the bias is increased. On the other hand, the reverse current exhibits thermally activated tunneling-type current. It was found that trapping centers at the p-CdTe/n-CdTe junction, which were formed due to the growth induced defects, determine the currents of this diode, and hence limit the performance of the nuclear radiation detectors developed.

  4. where f(x; y) represents the intensity of emitted radiation at location (x; y), ` is a given projection angle, and t is the detector location. The function P ` (t) is the

    E-print Network

    Duncan, James S.

    19 where f(x; y) represents the intensity of emitted radiation at location (x; y), ` is a given projection angle, and t is the detector location. The function P ` (t) is the projection of f(x; y) at angle `, which is the sum of f(x; y) values along a line t = x cos` + y sin`, and is called the Radon Transform

  5. Charged particle detectors with active detector surface for partial energy deposition of the charged particles and related methods

    DOEpatents

    Gerts, David W; Bean, Robert S; Metcalf, Richard R

    2013-02-19

    A radiation detector is disclosed. The radiation detector comprises an active detector surface configured to generate charge carriers in response to charged particles associated with incident radiation. The active detector surface is further configured with a sufficient thickness for a partial energy deposition of the charged particles to occur and permit the charged particles to pass through the active detector surface. The radiation detector further comprises a plurality of voltage leads coupled to the active detector surface. The plurality of voltage leads is configured to couple to a voltage source to generate a voltage drop across the active detector surface and to separate the charge carriers into a plurality of electrons and holes for detection. The active detector surface may comprise one or more graphene layers. Timing data between active detector surfaces may be used to determine energy of the incident radiation. Other apparatuses and methods are disclosed herein.

  6. Apparatuses and methods for detecting, identifying and quantitating radioactive nuclei and methods of distinguishing neutron stimulation of a radiation particle detector from gamma-ray stimulation of a detector

    DOEpatents

    Cole, Jerald D. (Idaho Falls, ID); Drigert, Mark W. (Idaho Falls, ID); Reber, Edward L. (Idaho Falls, ID); Aryaeinejad, Rahmat (Idaho Falls, ID)

    2001-01-01

    In one aspect, the invention encompasses a method of detecting radioactive decay, comprising: a) providing a sample comprising a radioactive material, the radioactive material generating decay particles; b)providing a plurality of detectors proximate the sample, the detectors comprising a first set and a second set, the first set of the detectors comprising liquid state detectors utilizing liquid scintillation material coupled with photo tubes to generate a first electrical signal in response to decay particles stimulating the liquid scintillation material, the second set of the detectors comprising solid state detectors utilizing a crystalline solid to generate a second electrical signal in response to decay particles stimulating the crystalline solid; c) stimulating at least one of the detectors to generate at least one of the first and second electrical signals, the at least one of the first and second electrical signals being indicative of radioactive decay in the sample. In another aspect, the invention encompasses an apparatus for identifying and quantitating radioactive nuclei of a sample comprising radioactive material that decays to generate neutrons and high-energy .gamma.-rays.

  7. High-resolution ionization detector and array of such detectors

    DOEpatents

    McGregor, Douglas S. (Ypsilanti, MI); Rojeski, Ronald A. (Pleasanton, CA)

    2001-01-16

    A high-resolution ionization detector and an array of such detectors are described which utilize a reference pattern of conductive or semiconductive material to form interaction, pervious and measurement regions in an ionization substrate of, for example, CdZnTe material. The ionization detector is a room temperature semiconductor radiation detector. Various geometries of such a detector and an array of such detectors produce room temperature operated gamma ray spectrometers with relatively high resolution. For example, a 1 cm.sup.3 detector is capable of measuring .sup.137 Cs 662 keV gamma rays with room temperature energy resolution approaching 2% at FWHM. Two major types of such detectors include a parallel strip semiconductor Frisch grid detector and the geometrically weighted trapezoid prism semiconductor Frisch grid detector. The geometrically weighted detector records room temperature (24.degree. C.) energy resolutions of 2.68% FWHM for .sup.137 Cs 662 keV gamma rays and 2.45% FWHM for .sup.60 Co 1.332 MeV gamma rays. The detectors perform well without any electronic pulse rejection, correction or compensation techniques. The devices operate at room temperature with simple commercially available NIM bin electronics and do not require special preamplifiers or cooling stages for good spectroscopic results.

  8. Optical detector calibrator system

    NASA Technical Reports Server (NTRS)

    Strobel, James P. (Inventor); Moerk, John S. (Inventor); Youngquist, Robert C. (Inventor)

    1996-01-01

    An optical detector calibrator system simulates a source of optical radiation to which a detector to be calibrated is responsive. A light source selected to emit radiation in a range of wavelengths corresponding to the spectral signature of the source is disposed within a housing containing a microprocessor for controlling the light source and other system elements. An adjustable iris and a multiple aperture filter wheel are provided for controlling the intensity of radiation emitted from the housing by the light source to adjust the simulated distance between the light source and the detector to be calibrated. The geared iris has an aperture whose size is adjustable by means of a first stepper motor controlled by the microprocessor. The multiple aperture filter wheel contains neutral density filters of different attenuation levels which are selectively positioned in the path of the emitted radiation by a second stepper motor that is also controlled by the microprocessor. An operator can select a number of detector tests including range, maximum and minimum sensitivity, and basic functionality. During the range test, the geared iris and filter wheel are repeatedly adjusted by the microprocessor as necessary to simulate an incrementally increasing simulated source distance. A light source calibration subsystem is incorporated in the system which insures that the intensity of the light source is maintained at a constant level over time.

  9. [{sup 18}F]fluoromisonidazole and a New PET System With Semiconductor Detectors and a Depth of Interaction System for Intensity Modulated Radiation Therapy for Nasopharyngeal Cancer

    SciTech Connect

    Yasuda, Koichi; Onimaru, Rikiya; Okamoto, Shozo; Shiga, Tohru; Katoh, Norio; Tsuchiya, Kazuhiko; Suzuki, Ryusuke; Takeuchi, Wataru; Kuge, Yuji; Tamaki, Nagara; Shirato, Hiroki

    2013-01-01

    Purpose: The impact of a new type of positron emission tomography (New PET) with semiconductor detectors using {sup 18}F-labeled fluoromisonidazole (FMISO)-guided intensity modulated radiation therapy (IMRT) was compared with a state-of-the-art PET/computed tomography (PET/CT) system in nasopharyngeal cancer (NPC) patients. Methods and Materials: Twenty-four patients with non-NPC malignant tumors (control group) and 16 patients with NPC were subjected to FMISO-PET. The threshold of the tumor-to-muscle (T/M) ratio in each PET scan was calculated. The hypoxic volume within the gross tumor volume (GTVh) was determined using each PET ({sub NewPET}GTVh and {sub PET/CT}GTVh, respectively). Dose escalation IMRT plans prescribing 84 Gy to each GTVh were carried out. Results: The threshold of the T/M ratio was 1.35 for New PET and 1.23 for PET/CT. The mean volume of {sub NewPET}GTVh was significantly smaller than that of {sub PET/CT}GTVh (1.5 {+-} 1.6 cc vs 4.7 {+-} 4.6 cc, respectively; P=.0020). The dose escalation IMRT plans using New PET were superior in dose distribution to those using PET/CT. Dose escalation was possible in all 10 New PET-guided plans but not in 1 PET/CT-guided plan, because the threshold dose to the brainstem was exceeded. Conclusions: New PET was found to be useful for accurate dose escalation in FMISO-guided IMRT for patients with NPC.

  10. Modular optical detector system

    DOEpatents

    Horn, Brent A. (Livermore, CA); Renzi, Ronald F. (Tracy, CA)

    2006-02-14

    A modular optical detector system. The detector system is designed to detect the presence of molecules or molecular species by inducing fluorescence with exciting radiation and detecting the emitted fluorescence. Because the system is capable of accurately detecting and measuring picomolar concentrations it is ideally suited for use with microchemical analysis systems generally and capillary chromatographic systems in particular. By employing a modular design, the detector system provides both the ability to replace various elements of the detector system without requiring extensive realignment or recalibration of the components as well as minimal user interaction with the system. In addition, the modular concept provides for the use and addition of a wide variety of components, including optical elements (lenses and filters), light sources, and detection means, to fit particular needs.

  11. Thermoluminescent Detectors in Mixed Fields

    E-print Network

    Mala, P; Biskup, B; Roeed, K

    2012-01-01

    This note reports on using of thermoluminescent detectors for radiation monitoring in the LHC tunnel and in the shielded areas around the tunnel. The accumulated annual doses in these areas vary a lot so a dosimeter used there should cover a large dose range. TL detectors can measure dose from 0.1 mGy to few kGy (with a recently proposed new technique which needs more studies up to 1 MGy). This report presents studies of these detectors in mixed fields similar to radiation field in the LHC and the possible usage of their results for calculation of high energy hadron and thermal neutron fluence.

  12. Progress in the Development of CdTe and CdZnTe Semiconductor Radiation Detectors for Astrophysical and Medical Applications

    PubMed Central

    Sordo, Stefano Del; Abbene, Leonardo; Caroli, Ezio; Mancini, Anna Maria; Zappettini, Andrea; Ubertini, Pietro

    2009-01-01

    Over the last decade, cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) wide band gap semiconductors have attracted increasing interest as X-ray and gamma ray detectors. Among the traditional high performance spectrometers based on silicon (Si) and germanium (Ge), CdTe and CdZnTe detectors show high detection efficiency and good room temperature performance and are well suited for the development of compact and reliable detection systems. In this paper, we review the current status of research in the development of CdTe and CdZnTe detectors by a comprehensive survey on the material properties, the device characteristics, the different techniques for improving the overall detector performance and some major applications. Astrophysical and medical applications are discussed, pointing out the ongoing Italian research activities on the development of these detectors. PMID:22412323

  13. Response measurement of single-crystal chemical vapor deposition diamond radiation detector for intense X-rays aiming at neutron bang-time and neutron burn-history measurement on an inertial confinement fusion with fast ignition

    NASA Astrophysics Data System (ADS)

    Shimaoka, T.; Kaneko, J. H.; Arikawa, Y.; Isobe, M.; Sato, Y.; Tsubota, M.; Nagai, T.; Kojima, S.; Abe, Y.; Sakata, S.; Fujioka, S.; Nakai, M.; Shiraga, H.; Azechi, H.; Chayahara, A.; Umezawa, H.; Shikata, S.

    2015-05-01

    A neutron bang time and burn history monitor in inertial confinement fusion with fast ignition are necessary for plasma diagnostics. In the FIREX project, however, no detector attained those capabilities because high-intensity X-rays accompanied fast electrons used for plasma heating. To solve this problem, single-crystal CVD diamond was grown and fabricated into a radiation detector. The detector, which had excellent charge transportation property, was tested to obtain a response function for intense X-rays. The applicability for neutron bang time and burn history monitor was verified experimentally. Charge collection efficiency of 99.5% ± 0.8% and 97.1% ± 1.4% for holes and electrons were obtained using 5.486 MeV alpha particles. The drift velocity at electric field which saturates charge collection efficiency was 1.1 ± 0.4 × 107 cm/s and 1.0 ± 0.3 × 107 cm/s for holes and electrons. Fast response of several ns pulse width for intense X-ray was obtained at the GEKKO XII experiment, which is sufficiently fast for ToF measurements to obtain a neutron signal separately from X-rays. Based on these results, we confirmed that the single-crystal CVD diamond detector obtained neutron signal with good S/N under ion temperature 0.5-1 keV and neutron yield of more than 109 neutrons/shot.

  14. Response measurement of single-crystal chemical vapor deposition diamond radiation detector for intense X-rays aiming at neutron bang-time and neutron burn-history measurement on an inertial confinement fusion with fast ignition

    SciTech Connect

    Shimaoka, T. Kaneko, J. H.; Tsubota, M.; Arikawa, Y.; Nagai, T.; Kojima, S.; Abe, Y.; Sakata, S.; Fujioka, S.; Nakai, M.; Shiraga, H.; Azechi, H.; Isobe, M.; Sato, Y.; Chayahara, A.; Umezawa, H.; Shikata, S.

    2015-05-15

    A neutron bang time and burn history monitor in inertial confinement fusion with fast ignition are necessary for plasma diagnostics. In the FIREX project, however, no detector attained those capabilities because high-intensity X-rays accompanied fast electrons used for plasma heating. To solve this problem, single-crystal CVD diamond was grown and fabricated into a radiation detector. The detector, which had excellent charge transportation property, was tested to obtain a response function for intense X-rays. The applicability for neutron bang time and burn history monitor was verified experimentally. Charge collection efficiency of 99.5% ± 0.8% and 97.1% ± 1.4% for holes and electrons were obtained using 5.486 MeV alpha particles. The drift velocity at electric field which saturates charge collection efficiency was 1.1 ± 0.4 × 10{sup 7} cm/s and 1.0 ± 0.3 × 10{sup 7} cm/s for holes and electrons. Fast response of several ns pulse width for intense X-ray was obtained at the GEKKO XII experiment, which is sufficiently fast for ToF measurements to obtain a neutron signal separately from X-rays. Based on these results, we confirmed that the single-crystal CVD diamond detector obtained neutron signal with good S/N under ion temperature 0.5–1 keV and neutron yield of more than 10{sup 9} neutrons/shot.

  15. QCD Gluon Radiation Studies Alex Buytenhuijs

    E-print Network

    van Suijlekom, Walter

    QCD Gluon Radiation Studies Alex Buytenhuijs with the L3 Detector (Yu.L.Dokshitzer ) May the colour force be with you. #12;QCD Gluon Radiation Studies Using the L3 Detector Een wetenschappelijke proeve op

  16. Nuclear radiation detectors based on a matrix of ion-implanted p-i-n diodes on undoped GaAs epilayers

    SciTech Connect

    Baryshnikov, F. M.; Britvich, G. I.; Chernykh, A. V.; Chernykh, S. V.; Chubenko, A. P.; Didenko, S. I.; Koltsov, G. I.

    2012-11-06

    Samples of nuclear detectors which represent matrices of p-i-n diodes were fabricated based on undoped gallium arsenide epitaxial layers by ion implantation technology. The detectors have a size of the active area of 0.4 Multiplication-Sign 0.4 and 0.9 Multiplication-Sign 0.9 cm{sup 2}. Electrical characteristics of fabricated detectors and results of measurements of fast neutrons spectra of {sup 241}Am-Be source by the recoil protons method are discussed.

  17. Development of a Plasma Panel Muon Detector

    SciTech Connect

    Levin, Daniel S.; Ball, Robert; Beene, James R; Benhammou, Yan; Chapman, J. Wehrley; Dai, T.; Etzion, E; Friedman, Dr. Peter S.; Ben Moshe, M.; Silver, Yiftah; Varner Jr, Robert L; Weaverdyck, Curtis; White, Sebastion; Zhou, Bing

    2010-01-01

    A radiation detector technology based on Plasma Display Panels (PDP), the underlying engine of panel plasma television displays is being investigated. Emerging from this well established television technology is the Plasma Panel Sensor (PPS), a novel variant of the micropattern radiation detector. The PPS is fundamentally a fast, high resolution detector comprised of an array of plasma discharge cells operating in a hermetically sealed gas mixture. We report on the PPS development effort, including proof-of-principle results of laboratory signal observations.

  18. Comparison of an electro-optical system and photo-conducting antenna employed as detectors of pulsed terahertz radiation by means of a new method for measuring spectral width

    NASA Astrophysics Data System (ADS)

    Grachev, Ya V.; Osipova, M. O.; Bespalov, V. G.

    2014-12-01

    Two detection systems, electro-optical system and photoconducting system, are tested by the method suggested previously for determining the boundaries of broadband terahertz radiation in time-domain spectroscopy. From a series of measurements the error in determining the operation ranges is calculated. The terahertz spectrometer with an electro-optical detector based on a ZnTe (110) crystal of thickness 2 mm has the operation spectral range of 0.059 - 1.092 THz. The detector utilizing an iPCA-21-05-1000-800-h photo-conducting antenna with the same source of signal demonstrates a wider operation band ranging from 0.017 to 1.6 THz. The method developed makes it possible to experimentally compare the parameters of the considered terahertz spectrometers obtained under the same quality of adjustment.

  19. Comparison of an electro-optical system and photo-conducting antenna employed as detectors of pulsed terahertz radiation by means of a new method for measuring spectral width

    SciTech Connect

    Grachev, Ya V; Osipova, M O; Bespalov, V G

    2014-12-31

    Two detection systems, electro-optical system and photoconducting system, are tested by the method suggested previously for determining the boundaries of broadband terahertz radiation in time-domain spectroscopy. From a series of measurements the error in determining the operation ranges is calculated. The terahertz spectrometer with an electro-optical detector based on a ZnTe (110) crystal of thickness 2 mm has the operation spectral range of 0.059 – 1.092 THz. The detector utilizing an iPCA-21-05-1000-800-h photo-conducting antenna with the same source of signal demonstrates a wider operation band ranging from 0.017 to 1.6 THz. The method developed makes it possible to experimentally compare the parameters of the considered terahertz spectrometers obtained under the same quality of adjustment. (laser applications and other topics in quantum electronics)

  20. Gamma ray detector modules

    NASA Technical Reports Server (NTRS)

    Capote, M. Albert (Inventor); Lenos, Howard A. (Inventor)

    2009-01-01

    A radiation detector assembly has a semiconductor detector array substrate of CdZnTe or CdTe, having a plurality of detector cell pads on a first surface thereof, the pads having a contact metallization and a solder barrier metallization. An interposer card has planar dimensions no larger than planar dimensions of the semiconductor detector array substrate, a plurality of interconnect pads on a first surface thereof, at least one readout semiconductor chip and at least one connector on a second surface thereof, each having planar dimensions no larger than the planar dimensions of the interposer card. Solder columns extend from contacts on the interposer first surface to the plurality of pads on the semiconductor detector array substrate first surface, the solder columns having at least one solder having a melting point or liquidus less than 120 degrees C. An encapsulant is disposed between the interposer circuit card first surface and the semiconductor detector array substrate first surface, encapsulating the solder columns, the encapsulant curing at a temperature no greater than 120 degrees C.