Science.gov

Sample records for fiber radiation detectors

  1. 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.

  2. 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

  3. Monitoring of Radiation Damage of Quartz Fibers in the Hf-Cms Detector

    NASA Astrophysics Data System (ADS)

    Merlo, Jean-Pierre

    2014-06-01

    Two HF calorimeters are in the range 3 < |η| <5 of CMS detector, made up of iron and quartz fibers assembled in towers red out by PMT's. Cherenkov light is produced in fibers by secondary electrons of showering particles. Accumulated luminosity decreases the light coming from fibers. A raddam device monitors this loss and is used to correct energies. Since 2010, 29 fb-1 were accumulated and "Raddam runs" were taken in beam stops. The raddam data are compared to our light transmission measurements of irradiated fibers. A FLUKA simulation of dose at 14 TeV for a luminosity accumulated of 3000 fb-1 is presented.

  4. The PAMELA Transition Radiation Detector

    NASA Astrophysics Data System (ADS)

    Cafagna, Francesco

    A Transition Radiation Detector (TRD) has been developed for the PAMELA instrument. PAMELA is a satellite born magnetic spectrometer; its primary scientific objective is the study of antiparticles in cosmic rays. The TRD detector was developed to provide particle identification, in addition to calorimetric measurements. This detector is composed of 9 active layers made of proportional straw tubes, piled up with interleaved carbon fibers radiator layers. Detector description and test beam performances will be presented.

  5. Fiber optic detector

    NASA Astrophysics Data System (ADS)

    Partin, Judy K.; Ward, Thomas E.; Grey, Alan E.

    1990-04-01

    This invention is comprised of a portable fiber optic detector that senses the presence of specific target chemicals by exchanging the target chemical for a fluorescently-tagged antigen that is bound to an antibody which is in turn attached to an optical fiber. Replacing the fluorescently-tagged antigen reduces the fluorescence so that a photon sensing detector records the reduced light level and activates an appropriate alarm or indicator.

  6. Fiber optic detector

    SciTech Connect

    Partin, J.K.; Ward, T.E.; Grey, A.E.

    1990-12-31

    This invention is comprised of a portable fiber optic detector that senses the presence of specific target chemicals by exchanging the target chemical for a fluorescently-tagged antigen that is bound to an antibody which is in turn attached to an optical fiber. Replacing the fluorescently-tagged antigen reduces the fluorescence so that a photon sensing detector records the reduced light level and activates an appropriate alarm or indicator.

  7. 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.

  8. Radiation detector

    DOEpatents

    Fultz, Brent T.

    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.

  9. 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.

  10. Adaptors for radiation detectors

    DOEpatents

    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.

  11. Fiber optic fluid detector

    DOEpatents

    Angel, S.M.

    1987-02-27

    Particular gases or liquids are detected with a fiber optic element having a cladding or coating of a material which absorbs the fluid or fluids and which exhibits a change of an optical property, such as index of refraction, light transmissiveness or fluoresence emission, for example, in response to absorption of the fluid. The fluid is sensed by directing light into the fiber optic element and detecting changes in the light, such as exit angle changes for example, that result from the changed optical property of the coating material. The fluid detector may be used for such purposes as sensing toxic or explosive gases in the atmosphere, measuring ground water contamination or monitoring fluid flows in industrial processes, among other uses. 10 figs.

  12. Fiber optic fluid detector

    DOEpatents

    Angel, S. Michael

    1989-01-01

    Particular gases or liquids are detected with a fiber optic element (11, 11a to 11j) having a cladding or coating of a material (23, 23a to 23j) which absorbs the fluid or fluids and which exhibits a change of an optical property, such as index of refraction, light transmissiveness or fluoresence emission, for example, in response to absorption of the fluid. The fluid is sensed by directing light into the fiber optic element and detecting changes in the light, such as exit angle changes for example, that result from the changed optical property of the coating material. The fluid detector (24, 24a to 24j) may be used for such purposes as sensing toxic or explosive gases in the atmosphere, measuring ground water contamination or monitoring fluid flows in industrial processes, among other uses.

  13. 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)

  14. RADIATION WAVE DETECTOR

    DOEpatents

    Wouters, L.F.

    1958-10-28

    The detection of the shape and amplitude of a radiation wave is discussed, particularly an apparatus for automatically indicating at spaced lntervals of time the radiation intensity at a flxed point as a measure of a radiation wave passing the point. The apparatus utilizes a number of photomultiplier tubes surrounding a scintillation type detector, For obtainlng time spaced signals proportional to radiation at predetermined intervals the photolnultiplier tubes are actuated ln sequence following detector incidence of a predetermined radiation level by electronic means. The time spaced signals so produced are then separately amplified and relayed to recording means.

  15. Microwave Radiation Detector

    NASA Technical Reports Server (NTRS)

    Lesh, J. R.

    1984-01-01

    Direct photon detector responds to microwave frequencies. Method based on trapped-ion frequency-generation standards proposed to detect radio-frequency (RF) radiation at 40.5 GHz. Technique used for directdetection (RF) communication, radar, and radio astronomy.

  16. Electromagnetic radiation detector

    DOEpatents

    Benson, Jay L.; Hansen, Gordon J.

    1976-01-01

    An electromagnetic radiation detector including a collimating window, a cathode member having a photoelectric emissive material surface angularly disposed to said window whereby radiation is impinged thereon at acute angles, an anode, separated from the cathode member by an evacuated space, for collecting photoelectrons emitted from the emissive cathode surface, and a negatively biased, high transmissive grid disposed between the cathode member and anode.

  17. Underwater radiation detector

    DOEpatents

    Kruse, Lyle W.; McKnight, Richard P.

    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.

  18. 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, γ-rays, β 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 γ-ray Emission (PIGE).

  19. 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.

  20. Amorphous silicon radiation detectors

    DOEpatents

    Street, Robert A.; Perez-Mendez, Victor; Kaplan, Selig N.

    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.

  1. Ionizing radiation detector

    DOEpatents

    Thacker, Louis H.

    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.

  2. Semiconductor radiation detector

    DOEpatents

    Patt, Bradley E.; Iwanczyk, Jan S.; Tull, Carolyn R.; Vilkelis, Gintas

    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.

  3. 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.

  4. 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.

  5. Photovoltaic radiation detector element

    DOEpatents

    Agouridis, Dimitrios C.

    1983-01-01

    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 the edge of which closely approaches but is spaced from the current collector strips.

  6. Precision synchrotron radiation detectors

    SciTech Connect

    Levi, M.; Rouse, F.; Butler, J.; Jung, C.K.; Lateur, M.; Nash, J.; Tinsman, J.; Wormser, G.; Gomez, J.J.; Kent, J.

    1989-03-01

    Precision detectors to measure synchrotron radiation beam positions have been designed and installed as part of beam energy spectrometers at the Stanford Linear Collider (SLC). The distance between pairs of synchrotron radiation beams is measured absolutely to better than 28 /mu/m on a pulse-to-pulse basis. This contributes less than 5 MeV to the error in the measurement of SLC beam energies (approximately 50 GeV). A system of high-resolution video cameras viewing precisely-aligned fiducial wire arrays overlaying phosphorescent screens has achieved this accuracy. Also, detectors of synchrotron radiation using the charge developed by the ejection of Compton-recoil electrons from an array of fine wires are being developed. 4 refs., 5 figs., 1 tab.

  7. Full Scale Coated Fiber Neutron Detector Measurements

    SciTech Connect

    Kouzes, Richard T.; Ely, James H.; Erikson, Luke E.; Kernan, Warnick J.; Stromswold, David C.; Woodring, Mitchell L.

    2010-03-17

    Radiation portal monitors used for interdiction of illicit materials at borders include highly sensitive neutron detection systems. The main reason for having neutron detection capability is to detect fission neutrons from plutonium. The currently deployed radiation portal monitors (RPMs) from Ludlum and Science Applications International Corporation (SAIC) use neutron detectors based upon 3He-filled gas proportional counters, which are the most common large neutron detector. There is a declining supply of 3He in the world, and thus, methods to reduce the use of this gas in RPMs with minimal changes to the current system designs and sensitivity to cargo-borne neutrons are being investigated. Four technologies have been identified as being currently commercially available, potential alternative neutron detectors to replace the use of 3He in RPMs. These technologies are: 1) Boron trifluoride (BF3)-filled proportional counters, 2) Boron-lined proportional counters, 3) Lithium-loaded glass fibers, and 4) Coated non-scintillating plastic fibers. Reported here are the results of tests of the full-scale 6Li/ZnS(Ag)-coated non-scintillating plastic fibers option. This testing measured the required performance for neutron detection efficiency and gamma ray rejection capabilities of a system manufactured by Innovative American Technology (IAT) and Saint Gobain, and is a follow-up report to an earlier one on a smaller prototype system.

  8. New IR detectors pig-tailed with IR fibers

    NASA Astrophysics Data System (ADS)

    Artiouchenko, Viatcheslav G.; Chekanova, Galina V.; Lartsev, Ivan Y.; Lobachev, Vladimir A.; Nikitine, Mikhail S.

    2003-09-01

    New generation of Mercury-Cadmium-Telluride (MCT) high performance infrared radiation (IR) detectors with IR-fiber input has been developed and fabricated. This new product is originated from 25 years experience in MCT detectors and IR fiber optics technologies. Range of products includes single- and multi-element detectors designed for registration of optical signals in spectral range from 2 to 18 μm. Detectors design is integrated or modular and includes package, sensitive element, cooling system, operating temperature sensor, optical components such as narrow band-pass filter and/or lens and/or different kind of optical window, optical connection unit and fiber pig-tail or fiber cable. Cooling system options include thermoelectric cooler, long-holding time dewar filled with liquid nitrogen, Joule-Thomson micro-liquidizer and Stirling-cycle cooler. Registered infrared radiation is delivered to sensitive area of detector through either Polycrystalline InfraRed (PIR-) Fiber (4 - 18 μm) or Chalcogenide IR-glass (CIR-) Fiber (2 - 6 μm). Unique feature intrinsic to Hg1-xCdxTe (MCT) alloys to form continuous series of alloy compositions "x" with proportionally changed energy gap Eg(x,T) allows to tune spectral responsivity of detector sensitive element with ordered spectral range and hence to use every time the highest sensitive detector.

  9. Radiation Hazard Detector

    NASA Technical Reports Server (NTRS)

    1978-01-01

    NASA technology has made commercially available a new, inexpensive, conveniently-carried device for protection, of people exposed to potentially dangerous levels of microwave radiation. Microwaves are radio emissions of extremely high frequency. They can be hazardous but the degree of hazard is not yet well understood. Generally, it is believed that low intensity radiation of short duration is not harmful but that exposure to high levels can induce deep internal burns, affecting the circulatory and nervous systems, and particularly the eyes. The Department of Labor's Occupational Safety and Health Administration (OSHA) has established an allowable safe threshold of exposure. However, people working near high intensity sources of microwave energy-for example, radar antennas and television transmitters-may be unknowingly exposed to radiation levels beyond the safe limit. This poses not only a personal safety problem but also a problem for employers in terms of productivity loss, workman's compensation claims and possible liability litigation. Earlier-developed monitoring devices which warn personnel of dangerous radiation levels have their shortcomings. They can be cumbersome and awkward to use while working. They also require continual visual monitoring to determine if a person is in a dangerous area of radiation, and they are relatively expensive, another deterrent to their widespread adoption. In response to the need for a cheaper and more effective warning system, Jet Propulsion Laboratory developed, under NASA auspices, a new, battery-powered Microwave Radiation Hazard Detector. To bring the product to the commercial market, California Institute Research Foundation, the patent holder, granted an exclusive license to Cicoil Corporation, Chatsworth, California, an electronic components manufacturer.

  10. Enhanced radiation resistant fiber optics

    DOEpatents

    Lyons, Peter B.; Looney, Larry D.

    1993-01-01

    A process for producing an optical fiber having enhanced radiation resitance is provided, the process including maintaining an optical fiber within a hydrogen-containing atmosphere for sufficient time to yield a hydrogen-permeated optical fiber having an elevated internal hydrogen concentration, and irradiating the hydrogen-permeated optical fiber at a time while the optical fiber has an elevated internal hydrogen concentration with a source of ionizing radiation. The radiation source is typically a cobalt-60 source and the fiber is pre-irradiated with a dose level up to about 1000 kilorads of radiation.

  11. Enhanced radiation resistant fiber optics

    DOEpatents

    Lyons, P.B.; Looney, L.D.

    1993-11-30

    A process for producing an optical fiber having enhanced radiation resistance is provided, the process including maintaining an optical fiber within a hydrogen-containing atmosphere for sufficient time to yield a hydrogen-permeated optical fiber having an elevated internal hydrogen concentration, and irradiating the hydrogen-permeated optical fiber at a time while the optical fiber has an elevated internal hydrogen concentration with a source of ionizing radiation. The radiation source is typically a cobalt-60 source and the fiber is pre-irradiated with a dose level up to about 1000 kilorads of radiation. 4 figures.

  12. Lithium Loaded Glass Fiber Neutron Detector Tests

    SciTech Connect

    Ely, James H.; Erikson, Luke E.; Kouzes, Richard T.; Lintereur, Azaree T.; Stromswold, David C.

    2009-11-12

    Radiation portal monitors used for interdiction of illicit materials at borders include highly sensitive neutron detection systems. The main reason for having neutron detection capability is to detect fission neutrons from plutonium. The currently deployed radiation portal monitors (RPMs) from Ludlum and Science Applications International Corporation (SAIC) use neutron detectors based upon 3He-filled gas proportional counters, which are the most common large neutron detector. There is a declining supply of 3He in the world and, thus, methods to reduce the use of this gas in RPMs with minimal changes to the current system designs and sensitivity to cargo-borne neutrons are being investigated. Four technologies have been identified as being currently commercially available, potential alternative neutron detectors to replace the use of 3He in RPMs. Reported here are the results of tests of the lithium-loaded glass fibers option. This testing measured the neutron detection efficiency and gamma ray rejection capabilities of a small system manufactured by Nucsafe (Oak Ridge, TN).

  13. Ship Effect Measurements With Fiber Optic Neutron Detector

    SciTech Connect

    King, Kenneth L.; Dean, Rashe A.; Akbar, Shahzad; Kouzes, Richard T.; Woodring, Mitchell L.

    2010-08-10

    The main objectives of this research project was to assemble, operate, test and characterize an innovatively designed scintillating fiber optic neutron radiation detector manufactured by Innovative American Technology with possible application to the Department of Homeland Security screening for potential radiological and nuclear threats at US borders (Kouzes 2004). One goal of this project was to make measurements of the neutron ship effect for several materials. The Virginia State University DOE FaST/NSF summer student-faculty team made measurements with the fiber optic radiation detector at PNNL above ground to characterize the ship effect from cosmic neutrons, and underground to characterize the muon contribution.

  14. Fiber optic thermal/fast neutron and gamma ray scintillation detector

    DOEpatents

    Neal, John S.; Mihalczo, John T.

    2006-11-28

    A detector system that combines a .sup.6Li loaded glass fiber scintillation thermal neutron detector with a fast scintillation detector in a single layered structure. Detection of thermal and fast neutrons and ionizing electromagnetic radiation is achieved in the unified detector structure. The fast scintillator replaces the polyethelene moderator layer adjacent the .sup.6Li loaded glass fiber panel of the neutron detector and acts as the moderator for the glass fibers. Fast neutrons, x-rays and gamma rays are detected in the fast scintillator. Thermal neutrons, x-rays and gamma rays are detected in the glass fiber scintillator.

  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. Fiber optic detector for immuno-testing

    DOEpatents

    Partin, Judy K.; Ward, Thomas E.; Grey, Alan E.

    1992-01-01

    A portable fiber optic detector that senses the presence of specific target chemicals in air or a gas by exchanging the target chemical for a fluoroescently-tagged antigen that is bound to an antibody which is in turn attached to an optical fiber. Replacing the fluorescently-tagged antigen reduces the fluorescence so that a photon sensing detector records the reduced light level and activates an appropriate alarm or indicator.

  17. Optical-Fiber Leak Detector

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.; Kosten, Susan E.

    1994-01-01

    Proposed optical-fiber sensor detects small changes in pressure in elastomeric O-ring or similar pressure seal, which may indicate deterioration of seal and interpreted as indications of incipient failure. According to concept, length of optical fiber embedded in seal. Light-emitting diode illuminates one end of fiber; photodetector measures intensity of light emerging from other end. Pressure-induced changes in seal bend fiber slightly, altering microbending-induced loss of light from fiber and alter intensity of light at photodetector. Change in intensity approximately proportional to change in pressure.

  18. Gaseous Radiation Detectors

    NASA Astrophysics Data System (ADS)

    Sauli, Fabio

    2014-06-01

    1. Introduction; 2. Electromagnetic interactions of charged particles with matter; 3. Interactions of photons and neutrons with matter; 4. Drift and diffusion of charges in gases; 5. Collisional excitations and charge multiplication in uniform fields; 6. Parallel plate counters; 7. Proportional counters; 8. Multiwire proportional chambers; 9. Drift chambers; 10. Time projection chambers; 11. Multitube arrays; 12. Resistive plate chambers; 13. Micro-pattern gas detectors; 14. Cherenkov ring imaging; 15. Miscellaneous detectors and applications; 16. Time degeneracy and aging; Further reading; References; Index.

  19. Photoacoustic tomography with integrating fiber-based annular detectors

    NASA Astrophysics Data System (ADS)

    Grün, H.; Altmisdört, H.; Berer, T.; Paltauf, G.; Zangerl, G.; Haltmeier, M.; Burgholzer, P.

    2011-03-01

    Photoacoustic tomography is an emerging technology combining the advantages of optical imaging (high contrast) and ultrasonic imaging (high spatial resolution). Applications for photoacoustic tomography are mainly in imaging soft tissue. For photoacoustic imaging the sample is illuminated by a short pulse of electromagnetic energy. Depending on the specific absorption rate (SAR) the electromagnetic radiation is absorbed and the subsequent thermoelastic expansion launches broadband ultrasonic waves. Usually point like piezo-electric detectors are used. Our group introduced integrating detectors a few years ago. This type of detector integrates the pressure at least along one dimension. Integrating line detectors, which integrate the pressure along one dimension, can be realized by using either free-beam or fiber-based interferometers. The latter approach also allows other detector shapes than a line. In this paper we use a fiber-based annular detector for tomography. Thereby the sample is rotated inside the annular detector on a position different from the symmetry axis of the annular detector. Hence the sample is enclosed by the detector and all data from one plane are collected at once. By moving the detector parallel to the symmetrie axis of the ring one can acquire data for a 3D image reconstruction. Therfore, tomography can be performed with only one rotation axis and one translation axis. For image reconstruction a novel algorithm is necessary which was tested on simulated data. Here we present an imaging setup using such a fiber-based annular detector. First measurements of simple structures and subsequent image reconstruction from these real data are shown in this paper.

  20. Cadmium telluride photovoltaic radiation detector

    DOEpatents

    Agouridis, D.C.; Fox, R.J.

    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 semi-conductive 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.

  1. Cadmium telluride photovoltaic radiation detector

    DOEpatents

    Agouridis, Dimitrios C.; Fox, Richard J.

    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.

  2. 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.

  3. 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.

  4. 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.

  5. Flexible composite radiation detector

    DOEpatents

    Cooke, D. Wayne; Bennett, Bryan L.; Muenchausen, Ross E.; Wrobleski, Debra A.; Orler, Edward B.

    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.

  6. Ionizing Radiation Detector

    DOEpatents

    Wright, Gomez W.; James, Ralph B.; Burger, Arnold; Chinn, Douglas A.

    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.

  7. 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.

  8. Radiation detector spectrum simulator

    DOEpatents

    Wolf, Michael A.; Crowell, John M.

    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.

  9. 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.

  10. Radiation detector arrangements and methods

    SciTech Connect

    Jackson, J.

    1989-08-01

    The patent describes a radiation detector arrangement. It comprises at least one detector element in the form of a temperature-sensitive resistor whose electrical resistance changes in response to radiation incident on the detector element, the resistor having a high positive temperature coefficient of electrical resistance at a transition in its electrical conductance, circuit means for applying a voltage across the resistor during operation of the detector arrangement, and temperature-regulation means for regulating the temperature of the resistor so as to operate the resistor in the transition, characterised in that the temperature-regulation means comprises the resistor and the circuit means which passes sufficient current through the resistor by resistance heating to a position in the transition at which a further increase in its temperature in response to incident radiation reduces the resistance heating by reducing the current, thereby stabilizing the temperature of the resistor at the position. The positive temperature coefficient at the position being sufficiently high that the change in the resistance heating produced by a change in the temperature of the resistor at the position is larger than a change in power of the incident radiation required to produce that same change in temperature of the resistor in the absence of any change in resistance heating.

  11. A space fiber-optic x-ray burst detector

    SciTech Connect

    Moss, C.E.; Casperson, D.E.; Echave, M.A.; Edwards, B.C.; Miller, J.R.; Saylor, W.W.; Sweet, M.R.; Valencia, J.E.

    1993-10-01

    We describe a novel, lightweight x-ray burst detector that can be embedded in a satellite structure, thus forming a ``smart skin,`` which has minimal impact on the host satellite. The design is based on two types of optical fibers coupled to photodiodes. The first is a scintillating fiber, which gives a fast signal for timing. The second is a germanium-doped silica fiber, which darkens for a few milliseconds when irradiated with a burst of x rays. The resulting slow signal is used to discriminate against electrostatic discharges. The coincidence of a fast signal from the scintillating fiber with a slow signal from the darkening fiber is the signature of an x-ray burst. The response is linear at low doses and becomes nonlinear at high doses. We have two techniques to test the instrument in a space experiment scheduled for 1994. First, a small, space-qualified flash x-ray unit can illuminate the fibers. Second, we can detect space background radiation. The cumulative dose will be monitored by RADFET dosimeters. Future work on embedding the fibers and the electronics as Application Specific Integrated Circuits (ASICs) in the spacecraft skin could lead to use of these detectors on many satellites.

  12. Direct detector for terahertz radiation

    DOEpatents

    Wanke, Michael C.; Lee, Mark; Shaner, Eric A.; Allen, S. James

    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.

  13. 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).

  14. Pocket-size microwave radiation hazard detector

    NASA Technical Reports Server (NTRS)

    Kolbly, R. B.

    1974-01-01

    Inexpensive lightweight unit is easily carried in coat pocket or attached to belt, detector sounds alarm in presence of dangerous microwave radiation levels. Unit consists of antenna, detector, level sensor, keyed oscillator, and speaker. Antenna may be single equiangular spiral or set of orthogonal slot dipoles. Signal detector is simple diode in small package.

  15. Radiation experience with the CDF silicon detectors

    SciTech Connect

    Husemann, Ulrich; /Rochester U.

    2005-11-01

    The silicon detectors of the CDF experiment at the Tevatron collider are operated in a harsh radiation environment. The lifetime of the silicon detectors is limited by radiation damage, and beam-related incidents are an additional risk. This article describes the impact of beam-related incidents on detector operation and the effects of radiation damage on electronics noise and the silicon sensors. From measurements of the depletion voltage as a function of the integrated luminosity, estimates of the silicon detector lifetime are derived.

  16. Electron gas grid semiconductor radiation detectors

    DOEpatents

    Lee, Edwin Y.; James, Ralph B.

    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.

  17. 49 CFR 173.310 - Exceptions for radiation detectors.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Exceptions for radiation detectors. 173.310... for radiation detectors. Radiation detectors, radiation sensors, electron tube devices, or ionization chambers, herein referred to as “radiation detectors,” that contain only Division 2.2 gases, are...

  18. 49 CFR 173.310 - Exceptions for radiation detectors.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Exceptions for radiation detectors. 173.310... for radiation detectors. Radiation detectors, radiation sensors, electron tube devices, or ionization chambers, herein referred to as “radiation detectors,” that contain only Division 2.2 gases, are...

  19. 49 CFR 173.310 - Exceptions for radiation detectors.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Exceptions for radiation detectors. 173.310... for radiation detectors. Radiation detectors, radiation sensors, electron tube devices, or ionization chambers, herein referred to as “radiation detectors,” that contain only Division 2.2 gases, are...

  20. 49 CFR 173.310 - Exceptions for radiation detectors.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Exceptions for radiation detectors. 173.310... for radiation detectors. Radiation detectors, radiation sensors, electron tube devices, or ionization chambers, herein referred to as “radiation detectors,” that contain only Division 2.2 gases, are...

  1. 49 CFR 173.310 - Exceptions for radiation detectors.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Exceptions for radiation detectors. 173.310... for radiation detectors. Radiation detectors, radiation sensors, electron tube devices, or ionization chambers, herein referred to as “radiation detectors,” that contain only Division 2.2 gases, are...

  2. 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.

  3. Two-dimensional position sensitive radiation detectors

    DOEpatents

    Mihalczo, John T.

    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.

  4. 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.

  5. Scintillator-fiber charged-particle track-imaging detector

    NASA Technical Reports Server (NTRS)

    Binns, W. R.; Israel, M. H.; Klarmann, J.

    1983-01-01

    A scintillator-fiber charged-particle track-imaging detector has been developed using a bundle of square cross-section plastic scintillator fiber optics, proximity focused onto an image intensified Charge Injection Device (CID) camera. Detector to beams of 15 MeV protons and relativistic Neon, Manganese, and Gold nuclei have been exposed and images of their tracks are obtained. This paper presents details of the detector technique, properties of the tracks obtained, and range measurements of 15 MeV protons stopping in the fiber bundle.

  6. Enhanced radiation detectors using luminescent materials

    DOEpatents

    Vardeny, Zeev V.; Jeglinski, Stefan A.; Lane, Paul A.

    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.

  7. 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.

  8. Wafer-fused semiconductor radiation detector

    DOEpatents

    Lee, Edwin Y.; James, Ralph B.

    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.

  9. Scintillating-fiber imaging detector for 14-MeV neutrons

    SciTech Connect

    Ress, D.; Lerche, R.A.; Ellis, R.J.; Heaton, G.W.; Nelson, M.B.; Mant, G.; Lehr, D.E.

    1994-07-25

    The authors have created a detector to image the neutrons emitted by imploded inertial-confinement fusion targets. The 14-MeV neutrons, which are produced by deuterium-tritium fusion events in the target, pass through an aperture to create an image on the detector. The neutron radiation is converted to blue light (430 nm) with a 20-cm-square array of plastic scintillating fibers. Each fiber is 10-cm long with a 1-mm-square cross section; approximately 35-thousand fibers make up the array. The resulting blue-light image is reduced and amplified by a sequence of fiber-optic tapers and image intensifiers, then acquired by a CCD camera. The fiber-optic readout system was tested optically for overall throughput the resolution. The authors plan to characterize the scintillator array reusing an ion-beam neutron source as well as DT-fusion neutrons emitted by inertial confinement targets. Characterization experiments will measure the light-production efficiency, spatial resolution, and neutron scattering within the detector. Several neutron images of laser-fusion targets have been obtained with the detector. Several neutron images of laser-fusion targets have been obtained with the detector. They describe the detector and their characterization methods, present characterization results, and give examples of the neutron images.

  10. Cable tunnel fire experiment study based on linear optical fiber fire detectors

    NASA Astrophysics Data System (ADS)

    Fan, Dian; Ding, Hongjun

    2013-09-01

    Aiming at exiting linear temperature fire detection technology including temperature sensing cable, fiber Raman scattering, fiber Bragg grating, this paper establish an experimental platform in cable tunnel, set two different experimental scenes of the fire and record temperature variation and fire detector response time in the processing of fire simulation. Since a small amount of thermal radiation and no flame for the beginning of the small-scale fire, only directly contacting heat detectors can make alarm response and the rest of other non- contact detectors are unable to respond. In large-scale fire, the alarm response time of the fiber Raman temperature sensing fire detector and fiber Bragg grating temperature sensing fire detector is about 30 seconds, and depending on the thermocouples' record the temperature over the fire is less than 35° in first 60 seconds of large-scale fire, while the temperature rising is more than 5°/min within the range of +/- 3m. According to the technical characteristics of the three detectors, the engineering suitability of the typical linear heat detectors in cable tunnels early fire detection is analyzed, which provide technical support for the preparation of norms.

  11. 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.

  12. Device for calibrating a radiation detector system

    DOEpatents

    Mc Fee, Matthew C.; Kirkham, Tim J.; Johnson, Tippi H.

    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.

  13. Resonant tuning fork detector for electromagnetic radiation.

    PubMed

    Pohlkötter, Andreas; Willer, Ulrike; Bauer, Christoph; Schade, Wolfgang

    2009-02-01

    A mechanical quartz microresonator (tuning fork) is used to detect electromagnetic radiation. The detection scheme is based on forces created due to the incident electromagnetic radiation on the piezoelectric tuning fork. A force can be created due to the transfer of the photon momentum of the incident electromagnetic radiation. If the surfaces of the tuning fork are nonuniformly heated, a second force acts on it, the so-called photophoretic force. These processes occur for all wavelengths of the incident radiation, making the detector suitable for sensing of ultraviolet, visible, and mid-infrared light, even THz-radiation. Here the detector is characterized in the visible range; noise analysis is performed for 650 nm and 5.26 microm. A linear power characteristic and the dependence on pulse lengths of the incoming light are shown. Examples for applications for the visible and mid-infrared spectral region are given by 2f and absorption spectroscopy of oxygen and nitric oxide, respectively.

  14. Study of cosmic radiation by underground detectors

    NASA Astrophysics Data System (ADS)

    de Marzo, C.

    1992-04-01

    The study of cosmic radiation using underground detectors has undergone remarkable progress in the last ten years. Today several big underground laboratories are taking data on general problems of particle astrophysics, around the world. The study of the physical content of the mu-signal is reviewed, with special attention given to the recent results obtained at the Gran Sasso Laboratory by means of the MACRO detector, which is the largest apparatus devoted to this research field at present.

  15. 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.

  16. 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.

  17. Scintillator-fiber charged particle track-imaging detector

    NASA Technical Reports Server (NTRS)

    Binns, W. R.; Israel, M. H.; Klarmann, J.

    1983-01-01

    A scintillator-fiber charged-particle track-imaging detector was developed using a bundle of square cross section plastic scintillator fiber optics, proximity focused onto an image intensified charge injection device (CID) camera. The tracks of charged particle penetrating into the scintillator fiber bundle are projected onto the CID camera and the imaging information is read out in video format. The detector was exposed to beams of 15 MeV protons and relativistic Neon, Manganese, and Gold nuclei and images of their tracks were obtained. Details of the detector technique, properties of the tracks obtained, and preliminary range measurements of 15 MeV protons stopping in the fiber bundle are presented.

  18. Infrared receiver having a cooled radiation detector

    SciTech Connect

    Van Antwerpen, H. C.

    1985-04-09

    An infrared receiver having an infrared radiation detector cooled by means of a cold-gas engine, the thermal contact between a cooling surface of the cold-gas engine and the radiation detector being obtained by an elastic thermally conducting bridge. The cylindrical bridge is comprised of a plurality of turns of a metal strip. Due to the presence of the bridge, a good thermal conduction and further a compensation for differences in thermal expansion coefficients of the materials used are obtained. The infrared receiver is particularly suitable for night vision apparatus.

  19. Radiation hardness characteristics of Si-PIN radiation detectors

    NASA Astrophysics Data System (ADS)

    Jeong, Manhee; Jo, Woo Jin; Kim, Han Soo; Ha, Jang Ho

    2015-06-01

    The Korea Atomic Energy Research Institute (KAERI) has fabricated Si-PIN radiation detectors with low leakage current, high resistivity (>11 kΩ cm) and low capacitance for high-energy physics and X-ray spectroscopy. Floating-zone (FZ) 6-in. diameter N-type silicon wafers, with <1 1 1> crystal orientation and 675 μm thick, were used in the detector fabrication. The active areas are 3 mm×3 mm, 5 mm×5 mm and 10 mm×10 mm. We used a double deep-diffused structure at the edge of the active area for protection from the surface leakage path. We also compared the electrical performance of the Si-PIN detector with anti-reflective coating (ARC). For a detector with an active area of 3 mm×3 mm, the leakage current is about 1.9 nA and 7.4 nA at a 100 V reverse bias voltage, and 4.6 pF and 4.4 pF capacitance for the detector with and without an ARC, respectively. In addition, to compare the energy resolution in terms of radiation hardness, we measured the energy spectra with 57Co and 133Ba before the irradiation. Using developed preamplifiers (KAERI-PA1) that have ultra-low noise and high sensitivity, and a 3 mm×3 mm Si-PIN radiation detector, we obtained energy resolutions with 122 keV of 57Co and 81 keV of 133Ba of 0.221 keV and 0.261 keV, respectively. After 10, 100, 103, 104 and 105 Gy irradiation, we tested the characteristics of the radiation hardness on the Si-PIN radiation detectors in terms of electrical and energy spectra performance changes. The fabricated Si-PIN radiation detectors are working well under high dose irradiation conditions.

  20. Low-cost fiber-optic chemochromic hydrogen detector

    SciTech Connect

    Benson, D.K.; Tracy, C.E.; Hishmeh, G.; Ciszek, P.; Lee, S.H.

    1998-08-01

    The ability to detect hydrogen gas leaks economically and with inherent safety is an important technology that could facilitate commercial acceptance of hydrogen fuel in various applications. In particular, hydrogen fueled passenger vehicles will require hydrogen leak detectors to signal the activation of safety devices such as shutoff valves, ventilating fans, alarms, etc. Such detectors may be required in several locations within a vehicle--wherever a leak could pose a safety hazard. It is therefore important that the detectors be very economical. This paper reports progress on the development of low-cost fiber-optic hydrogen detectors intended to meet the needs of a hydrogen-fueled passenger vehicle. In the design, the presence of hydrogen in air is sensed by a thin-film coating at the end of a polymer optical fiber. When the coating reacts reversibly with the hydrogen, its optical properties are changed. Light from a central electro-optic control unit is projected down the optical fiber where it is reflected from the sensor coating back to central optical detectors. A change in the reflected intensity indicates the presence of hydrogen. The fiber-optic detector offers inherent safety by removing all electrical power from the leak sites and offers reduced signal processing problems by minimizing electromagnetic interference. Critical detector performance requirements include high selectivity, response speed and durability as well as potential for low-cost production.

  1. 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.

  2. Imaging radiation detector with gain

    DOEpatents

    Morris, Christopher L.; Idzorek, George C.; Atencio, Leroy G.

    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.

  3. 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.

  4. A transition radiation detector prototype to measure the energy of muons in cosmic ray laboratories

    NASA Astrophysics Data System (ADS)

    Bellotti, R.; Cafagna, F.; Calicchio, M.; Castellano, M.; De Cataldo, G.; De Marzo, C.; Enriquez, O.; Favuzzi, C.; Fusco, P.; Giglietto, N.; Mongelli, M.; Nappi, E.; Perchiazzi, M.; Sacchetti, A.; Spinelli, P.

    1991-07-01

    We have developed and tested a transition radiation detector prototype suitable to measure the energy of muons in cosmic ray laboratories. The technical solutions adopted, based on extruded tubes as detectors and foam or fiber mats as radiators, allow to cover very large areas with a low number of channels and ensure stability of operation. Using an argon-carbon dioxide gas mixture it is possible to explore the muon energy range up to 1 TeV.

  5. Scintillation fiber array detector for measurement of neutron beam profile

    NASA Astrophysics Data System (ADS)

    Kim, Chong; Hong, Byungsik; Jo, Mihee; Lee, Kyong Sei; Sim, Kwang-Souk

    2009-10-01

    We built and tested a detector to measure the profile of fast-neutron beams delivered by the MC50 cyclotron at the Korea Institute of Radiological and Medical Science (KIRAMS). The core component of the detector is a 2×46 array of scintillation fibers. The light output of the scintillation fibers is transformed into a current signal by a 46-channel silicon photodiode and digitized by a current-mode signal processor. This scanning device was designed to cover a neutron beam area of 30×32 cm2. The detector was tested in a neutron beam delivered by the MC50 cyclotron at KIRAMS. We demonstrate that the detector can successfully measure the neutron beam profile at various beam currents from 10 to 20 μA. The proposed neutron beam profile detector will be useful, for example, in radiotherapy applications with neutron intensities above 107 Hz/cm2.

  6. Thermal stability of grafted fibers. [Gamma radiation

    SciTech Connect

    Sundardi, F.; Kadariah; Marlianti, I.

    1983-10-01

    Presented the experimental results on the study of thermal stability of grafted fibers, i.e., polypropylene-, polyester-, and rayon-grafted fibers. These fibers were obtained by radiation grafting processes using hydrophylic monomers such as 1-vinyl 2-pyrolidone, acrylic acid, N-methylol acrylamide, and acrylonitrile. The thermal stability of the fibers was studied using a Shimadzu Thermal Analyzer DT-30. The thermal stability of the fibers, which can be indicated by the value of the activation energy for thermal degradation, was not improved by radiation grafting. The degree of improvement depends on the thermal stability of the monomers used for grafting. The thermal stability of a polypropylene fiber, either a grafted or an ungrafted one, was found to be inferior compared to the polyester of a rayon fiber, which may be due to the lack of C=O and C=C bonds in the polypropylene molecules. The thermal stability of a fiber grafted with acrylonitrile monomer was found to be better than that of an ungrafted one. However, no improvement was detected in the fibers grafted with 1-vinyl 2-pyrrolidone monomer, which may be due to the lower thermal stability of poly(1-vinyl-2-pyrrolidone), compared to the polypropylene or polyester fibers. 17 figures, 3 tables.

  7. Bismuth tri-iodide radiation detector development

    NASA Astrophysics Data System (ADS)

    Gokhale, Sasmit S.

    Bismuth tri-iodide is an attractive material for room temperature radiation detection. BiI3 demonstrates a number of properties that are apt for semiconductor radiation detection, especially gamma ray spectroscopy. The high atomic number (ZBi = 83 and ZI = 53) and the relatively high density (5.78 g/cm3) cause the material to have good photon stopping power, while the large band-gap (1.67 eV ) allows it to function as a room temperature radiation detector without any cooling mechanism. This work presents the fabrication and characterization of BiI3 radiation detectors. For the purpose of this research detectors were fabricated by cutting BiI3 crystal boules, followed by mechanical and chemical surface treatments. Detectors with various electrode geometries enabling single polarity charge sensing were fabricated. The electrical characteristics and the radiation response of the detectors were measured. The radiation response measurement was performed at room temperature using a 241Am alpha particle source and a 241Am sealed gamma-ray source. The spectral resolutions of the detectors varied from 2.09% - 6.1% for 59.5 keV gamma-rays and between 26% - 40% for 5.48 MeV alpha particles. Charge carrier properties such as the electron and hole mobility and lifetime were also estimated. The electron mobility for an ultrapure BiI 3 detector was estimated to be approximately 433 cm 2/Vs while that for antimony doped BiI3 was estimated to be around 956 cm2/Vs and the mobility-lifetime product for electrons was estimated to be around 5.44 x 10-4 cm 2/V. Detector simulation was performed using the Monte Carlo simulation code MCNP5. A Matlab script which incorporates charge carrier trapping and statistical variation was written to generate a gamma-ray spectrum from the simulated energy deposition spectra. Measured and simulated spectra were compared to extract the charge carrier mobility-lifetime products, which for electrons and holes were estimated to be 5 x 10-3 cm2/V and 1.3 x

  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. Radiation detectors: needs and prospects

    SciTech Connect

    Armantrout, G.A.

    1981-01-01

    Important applications for x- and ..gamma..-ray spectroscopy are found in prospecting, materials characterization, environmental monitoring, the life sciences, and nuclear physics. The specific requirements vary for each application with varying degrees of emphasis on either spectrometer resolution, detection efficiency, or both. Since no one spectrometer is ideally suited to this wide range of needs, compromises are usually required. Gas and scintillation spectrometers have reached a level of maturity, and recent interest has concentrated on semiconductor spectrometers. Germanium detectors are showing continuing refinement and are the spectrometers of choice for high resolution applications. The new high-Z semiconductors, such as CdTe and HgI/sub 2/, have shown steady improvement but are limited in both resolution and size and will likely be used only in applications which require their unique properties.

  10. 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.

  11. Development of a silicon carbide radiation detector

    SciTech Connect

    Ruddy, F.H.; Dulloo, A.R.; Seidel, J.G.; Seshadri, S.; Rowland, L.B.

    1998-06-01

    The radiation detection properties of semiconductor detectors made of 4H silicon carbide were evaluated. Both Schottky and p-n junction devices were tested. Exposure to alpha particles from a {sup 238}Pu source led to robust signals from the detectors. The resolution of the Schottky SiC detector was 5.8% (FWHM) at an energy of 294 keV, while that of the p-n junction was 6.6% (FWHM) at 260 keV. No effect of temperature in the range of 22 to 89 C was observed on the characteristics of the {sup 238}Pu alpha-induced signal from the SiC detector. In addition, testing in a gamma field of 10,000 rad-Si h{sup {minus}1} showed that the alpha-induced signal was separable from the gamma signal.

  12. Silicon radiation detectors: materials and applications

    SciTech Connect

    Walton, J.T.; Haller, E.E.

    1982-10-01

    Silicon nuclear radiation detectors are available today in a large variety of sizes and types. This profusion has been made possible by the ever increasing quality and diameter silicon single crystals, new processing technologies and techniques, and innovative detector design. The salient characteristics of the four basic detector groups, diffused junction, ion implanted, surface barrier, and lithium drift are reviewed along with the silicon crystal requirements. Results of crystal imperfections detected by lithium ion compensation are presented. Processing technologies and techniques are described. Two recent novel position-sensitive detector designs are discussed - one in high-energy particle track reconstruction and the other in x-ray angiography. The unique experimental results obtained with these devices are presented.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. 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

  15. High resolution amorphous silicon radiation detectors

    DOEpatents

    Street, Robert A.; Kaplan, Selig N.; Perez-Mendez, Victor

    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.

  16. 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.

  17. The Radiation Assessment Detector (RAD) Investigation

    NASA Astrophysics Data System (ADS)

    Hassler, D. M.; Zeitlin, C.; Wimmer-Schweingruber, R. F.; Böttcher, S.; Martin, C.; Andrews, J.; Böhm, E.; Brinza, D. E.; Bullock, M. A.; Burmeister, S.; Ehresmann, B.; Epperly, M.; Grinspoon, D.; Köhler, J.; Kortmann, O.; Neal, K.; Peterson, J.; Posner, A.; Rafkin, S.; Seimetz, L.; Smith, K. D.; Tyler, Y.; Weigle, G.; Reitz, G.; Cucinotta, F. A.

    2012-09-01

    The Radiation Assessment Detector (RAD) on the Mars Science Laboratory (MSL) is an energetic particle detector designed to measure a broad spectrum of energetic particle radiation. It will make the first-ever direct radiation measurements on the surface of Mars, detecting galactic cosmic rays, solar energetic particles, secondary neutrons, and other secondary particles created both in the atmosphere and in the Martian regolith. The radiation environment on Mars, both past and present, may have implications for habitability and the ability to sustain life. Radiation exposure is also a major concern for future human missions. The RAD instrument combines charged- and neutral-particle detection capability over a wide dynamic range in a compact, low-mass, low-power instrument. These capabilities are required in order to measure all the important components of the radiation environment. RAD consists of the RAD Sensor Head (RSH) and the RAD Electronics Box (REB) integrated together in a small, compact volume. The RSH contains a solid-state detector telescope with three silicon PIN diodes for charged particle detection, a thallium doped Cesium Iodide scintillator, plastic scintillators for neutron detection and anti-coincidence shielding, and the front-end electronics. The REB contains three circuit boards, one with a novel mixed-signal ASIC for processing analog signals and an associated control FPGA, another with a second FPGA to communicate with the rover and perform onboard analysis of science data, and a third board with power supplies and power cycling or "sleep"-control electronics. The latter enables autonomous operation, independent of commands from the rover. RAD is a highly capable and highly configurable instrument that paves the way for future compact energetic particle detectors in space.

  18. 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.

  19. Alpha-beta radiation detector

    DOEpatents

    Fleming, Dale M.; Simmons, Kevin L.; Froelich, Thomas J.; Carter, Gregory L.

    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.

  20. 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.

  1. 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.

  2. 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.

  3. Window for radiation detectors and the like

    DOEpatents

    Sparks, C.J. Jr.; Ogle, J.C.

    1975-10-28

    An improved x- and gamma-radiation and particle transparent window for the environment-controlling enclosure of various types of radiation and particle detectors is provided by a special graphite foil of a thickness of from about 0.1 to 1 mil. The graphite must have very parallel hexagonal planes with a mosaic spread no greater than 5$sup 0$ to have the necessary strength in thin sections to support one atmosphere or more of pressure. Such graphite is formed by hot- pressing and annealing pyrolytically deposited graphite and thereafter stripping off layers of sufficient thickness to form the window.

  4. 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.

  5. Miniature detector measures deep space radiation

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2011-08-01

    The 1972 journey of Apollo 17 marked not only the last time a human walked on the Moon but also the most recent manned venture beyond the outer reaches of the Earth's atmosphere. With preparations being made for humans to once again explore deep space, important steps are under way to quantify the hazards of leaving low-Earth orbit. One significant risk for long-distance missions is the increased exposure to ionizing radiation—energetic particles that can strip electrons off of otherwise neutral materials, affecting human health and the functioning of spacecraft equipment. The deep space probes that are being sent to measure the risks from ionizing radiation and other hazards can be costly, so maximizing the scientific value of each launch is important. With this goal in mind, Mazur et al. designed and developed a miniature dosimeter that was sent into lunar orbit aboard NASA's Lunar Reconnaissance Orbiter (LRO) in 2009. Weighing only 20 grams, the detector is able to measure fluctuations in ionizing radiation as low as 1 microrad (equivalent to 1.0 × 10-8 joules of energy deposited into 1 kilogram) while requiring minimal power and computer processing. The postage stamp-sized detector tracked radiation dosages for the first year of LRO's mission, with the results being confirmed by other onboard and near-Earth detectors. (Space Weather, doi:10.1029/2010SW000641, 2011)

  6. Position sensitivity in gallium arsenide radiation detectors

    SciTech Connect

    Harper, R.; Hilko, R.A.

    1994-12-31

    For several years, the authors have studied the electrical output of GaAs detectors in response to MeV protons. Beams from the Los Alamos National Laboratory`s tandem Van de Graaff, bunched into pulses of about 0.7-ns width, have been used to drive detectors into the current mode, and fast electronics have enabled characterization of the impulse response shapes and the absolute sensitivities. Recently, the authors extended this line of investigation to measure output-charge spectra in response to low-current beams, in which the count rate was low and pulses due to individual ionizing particles were analyzed. The first part of the work was the measurement of spectra of the output charge of the detectors when bombarded by a beam of MeV-energy protons, which was collimated to a diameter of 0.1 mm. The GaAs detector was mounted on a microadjustable stage just behind the collimator, so that the site of irradiation on the detector could be varied. Output pulses originating from the impacts of individual protons were preamplified with charge-sensitive Lecroy 2004 preamplifiers, shaped with Lecroy 2011 amplifiers, and analyzed with a Lecroy 3500 multichannel analyzer. The second part was the measurement of the time response of the detector to a 0.1 mm-collimated bunched proton beam. The proton bunch width was less than 1 ns, during which time many protons struck the detector, driving it into the current mode where individual proton impacts are unresolved. A possible detector design is suggested by the results. In the past, GaAs time response has been improved by doping or radiation damaging, which introduces traps. The tails can be eliminated, but at the cost of a factor of a thousand in main peak sensitivity. It now appears that by masking off the region of the detector near the negative electrode, the tails can be eliminated with only a factor of about ten loss in peak gain.

  7. CVD diamond detectors for radiation pulse characterisation

    NASA Astrophysics Data System (ADS)

    Foulon, F.; Bergonzo, P.; Jany, C.; Gicquel, A.; Pochet, T.

    Polycrystalline diamond films deposited by microwave plasma-enhanced chemical vapour deposition (MPCVD) have been used for the fabrication of resistive photoconductors. Such detectors can be used to measure the intensity and the temporal shape of pulsed radiation such as IR, visible, UV and X-rays. The photodetector response times were characterised under fast Nd:Yag laser pulses ( λ = 266 nm, τL = 30 ps at FWHM). The detector sensitivities were measured under both pulsed UV laser and steady-state X-ray excitations (40 keV). The detector response time strongly depends on the CVD diamond film structural and physical properties, i.e., the film growth conditions. They exhibit a response signal presenting full widths at half maximum down to about 100 ps and decay times down to about 130 ps. The diamond detector responses are compared to the responses measured on typical ultrafast photoconductors made from gallium arsenide pre-irradiated at 3 × 10 15 neutrons/cm 2 as well as from natural type IIa bulk diamond.

  8. Radiation simulations of the CMS detector

    NASA Astrophysics Data System (ADS)

    Stoddard, Graham J.

    This thesis presents results of recent radiation simulations for the Compact Muon Solenoid detector at the Large Hadron Collider at CERN performed using the Monte Carlo simulation package FLUKA. High statistics simulations with a fine granularity in the detector were carried out using the Condor batch system at the Fermilab LHC Physics Center. In addition, an existing web tool for accessing and displaying simulation data was upgraded. The FLUKA data and previously generated MARS Monte Carlo data can be plotted using 1-D or 2-D plotting functionalities along R and Z, the transverse distance from the beamline and the distance along the beamline, respectively. Comparisons between the data sets have been carried out; the effect of particle transport thresholds in both packages was explored, comparisons with zero magnetic field in the CMS solenoid and full field are made, a model of non-ionizing energy losses is examined, and sensitive areas of interest within the simulation are identified.

  9. Specialty fiber optic applications for harsh and high radiation environments

    NASA Astrophysics Data System (ADS)

    Risch, Brian G.

    2015-05-01

    Since the first commercial introduction in the 1980s, optical fiber technology has undergone an almost exponential growth. Currently over 2 billion fiber kilometers are deployed globally with 2014 global optical fiber production exceeding 300 million fiber kilometers. 1 Along with the staggering growth in optical fiber production and deployment, an increase in optical fiber technologies and applications has also followed. Although the main use of optical fibers by far has been for traditional data transmission and communications, numerous new applications are introduced each year. Initially the practical application of optical fibers was limited by cost and sensitivity of the optical fibers to stress, radiation, and other environmental factors. Tremendous advances have taken place in optical fiber design and materials allowing optical fibers to be deployed in increasingly harsh environments with exposure to increased mechanical and environmental stresses while maintaining high reliability. With the increased reliability, lower cost, and greatly expanded range of optical fiber types now available, new optical fiber deployments in harsh and high radiation environments is seeing a tremendous increase for data, communications, and sensing applications. An overview of key optical fiber applications in data, communications, and sensing for harsh environments in industrial, energy exploration, energy generation, energy transmission, and high radiation applications will be presented. Specific recent advances in new radiation resistant optical fiber types, other specialty optical fibers, optical fiber coatings, and optical fiber cable materials will be discussed to illustrate long term reliability for deployment of optical fibers in harsh and high radiation environments.

  10. Three dimensional imaging detector employing wavelength-shifting optical fibers

    DOEpatents

    Worstell, W.A.

    1997-02-04

    A novel detector element structure and method for its use is provided. In a preferred embodiment, one or more inorganic scintillating crystals are coupled through wavelength shifting optical fibers (WLSFs) to position sensitive photomultipliers (PS-PMTs). The superior detector configuration in accordance with this invention is designed for an array of applications in high spatial resolution gamma ray sensing with particular application to SPECT, PET and PVI imaging systems. The design provides better position resolution than prior art devices at a lower total cost. By employing wavelength shifting fibers (WLSFs), the sensor configuration of this invention can operate with a significant reduction in the number of photomultipliers and electronics channels, while potentially improving the resolution of the system by allowing three dimensional reconstruction of energy deposition positions. 11 figs.

  11. Three dimensional imaging detector employing wavelength-shifting optical fibers

    DOEpatents

    Worstell, William A.

    1997-01-01

    A novel detector element structure and method for its use is provided. In a preferred embodiment, one or more inorganic scintillating crystals are coupled through wavelength shifting optical fibers (WLSFs) to position sensitive photomultipliers (PS-PMTs). The superior detector configuration in accordance with this invention is designed for an array of applications in high spatial resolution gamma ray sensing with particular application to SPECT, PET and PVI imaging systems. The design provides better position resolution than prior art devices at a lower total cost. By employing wavelength shifting fibers (WLSFs), the sensor configuration of this invention can operate with a significant reduction in the number of photomultipliers and electronics channels, while potentially improving the resolution of the system by allowing three dimensional reconstruction of energy deposition positions.

  12. Radiation detector having a multiplicity of individual detecting elements

    DOEpatents

    Whetten, Nathan R.; Kelley, John E.

    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.

  13. Portable radiation detector and mapping system

    SciTech Connect

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

    1995-09-01

    A portable radiation detector and mapping system (RADMAPS) has been developed to detect, locate and plot nuclear radiation intensities on commercially available digital maps and other images. The field unit records gamma-ray spectra or neutron signals together with positions from a Global Positioning System (GPS) on flash memory cards. The recorded information is then transferred to a lap-top computer for spectral data analyses and then georegistered graphically on maps, photographs, etc. RADMAPS integrates several existing technologies to produce a preprogrammable field unit uniquely suited for each survey, as required. The system presently records spectra from a Nal(Tl) gamma-ray detector or an enriched Li-6 doped glass neutron scintillator. Standard Geographic Information System software installed in a lap-top, complete with CD-ROM supporting digitally imaged maps, permits the characterization of nuclear material in the field when the presence of such material is not otherwise documented. This paper gives the results of a typical site survey of the Savannah River Site (SRS) using RADMAPS.

  14. Portable radiation detector and mapping system

    SciTech Connect

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

    1995-12-31

    A portable radiation detector and mapping system (RADMAPS) has been developed to detect, locate, and plot nuclear radiation intensities on commercially available digital maps and other images. The field unit records gamma-ray spectra or neutron signals together with positions from a global positioning system (GPS) on flash memory cards. The recorded information is then transferred to a laptop computer for spectral data analyses and then georegistered graphically on maps, photographs, etc. RADMAPS integrates several existing technologies to produce a preprogrammable field unit uniquely suited for each survey, as required. The system records spectra from a NaI(Tl) gamma-ray detector or an enriched {sup 6}Li doped glass neutron scintillator. Standard Geographic Information System (GIS) software installed in a lap-top, complete with CD-ROM supporting digitally imaged maps, permits the characterization of nuclear material in the field when the presence of such material is not otherwise documented. This paper gives the results of a typical site survey of the Savannah River site (SRS) using RADMAPS. The ability to provide rapid field data should be of use in treaty verification, safeguards, decontamination, and nuclear weapons dismantlement.

  15. 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.

  16. Radiation oxidation and subsequent thermal curing of polyacrylonitrile fiber

    NASA Astrophysics Data System (ADS)

    Liu, Weihua; Wang, Mouhua; Xing, Zhe; Wu, Guozhong

    2014-01-01

    Polyacrylonitrile (PAN) fibers were exposed to gamma-ray irradiation at room temperature under vacuum, air and oxygen to investigate the radiation oxidation effects on PAN fibers. Radiation-induced oxidation degradation and crosslinking was evaluated by measuring the gel fraction. It was found that radiation oxidation took place mainly on the fiber surface due to the limited penetration of oxygen into PAN fibers from the surface, and the oxidation thickness increased with the oxygen pressure. Chain scission was dominant in the oxidized area, and crosslinking occurred in the inner part of the fibers. However, the oxidized regions of the fibers can be converted to gel via crosslinking by thermal curing at 160 °C in a N2 atmosphere. Higher extents of radiation oxidation degradation led to a greater increase in the gel fraction. These results suggest that the radiation treatment of PAN fibers prior to thermal oxidation may be useful for manufacturing carbon fibers.

  17. 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.

  18. 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.

  19. 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.

  20. New radiation detectors for field measurements

    SciTech Connect

    Bhattacharjie, A.; Quam, W.

    1993-12-31

    Two new types of radiation detectors are discussed; the first is a large area TLD and the second is a high pressure xenon proportional counter. The large area TLD can be used to measure In situ alpha activity with high spatial resolution and high sensitivity. Some field measurements are presented. The high pressure xenon proportional counter (XGPC) is capable of realtime survey work and monitoring of plutonium (through detection of the 60 keV Americium-241 gamma ray) and uranium. Spectral resolution data from the 8 atmosphere proportional counter are presented. In many applications the counting efficiency penalty due to low stopping power of xenon at higher gamma energies can be offset by increasing gas pressure and using physically long counters.

  1. 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.

  2. Real-time self-networking radiation detector apparatus

    DOEpatents

    Kaplan, Edward; Lemley, James; Tsang, Thomas Y.; Milian, Laurence W.

    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.

  3. Dependence of dark count rates in superconducting single photon detectors on the filtering effect of standard single mode optical fibers

    NASA Astrophysics Data System (ADS)

    Smirnov, Konstantin; Vachtomin, Yury; Divochiy, Alexander; Antipov, Andrey; Goltsman, Gregory

    2015-02-01

    We found that background radiation limits the dark count rates of superconducting single photon detectors coupled to standard single mode optical fibers to a minimum level when the source temperature of the photons is close to 300 K. We measured this level to be 103 cps, which was confirmed by a theoretical analysis of the background radiation influence. We also investigated the filtering-effect of cooled single mode optical fibers with different bending diameters and showed that for superconducting photon receivers with operating wavelengths below 2 µm the minimum dark count rate can be significantly decreased down to 0.1 cps.

  4. Wire chamber radiation detector with discharge control

    DOEpatents

    Perez-Mendez, Victor; Mulera, Terrence A.

    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.

  5. Radiation damage studies for the D0 silicon detector

    SciTech Connect

    Lehner, F.; /Zurich U.

    2004-01-01

    We report on irradiation studies performed on spare production silicon detector modules for the current D0 silicon detector. The lifetime expectations due to radiation damage effects of the existing silicon detector are reviewed. A new upgrade project was started with the goal of a complete replacement of the existing silicon detector. In that context, several investigations on the radiation hardness of new prototype silicon microstrip detectors were carried out. The irradiation on different detector types was performed with 10 MeV protons up to fluences of 10{sup 14} p/cm{sup 2} at the J.R. Mcdonald Laboratory at Kansas State University. The flux calibration was carefully checked using different normalization techniques. As a result, we observe roughly 40-50% less radiation damage in silicon for 10 MeV p exposure than it is expected by the predicted NIEL scaling.

  6. Radiation environment and shielding for a high luminosity collider detector

    SciTech Connect

    Diwan, M.V.; Fisyak, Y.; Mokhov, N.V.

    1995-12-01

    Detectors now under design for use in the proposed high energy high luminosity colliders must deal with unprecedented radiation levels. We have performed a comprehensive study for the GEM detector at the SSC to determine the best way to shield critical detector components from excessive radiation, with special attention paid to the low energy neutrons and photons. We have used several detailed Monte-Carlo simulations to calculate the particle fluxes in the detector. We describe these methods and demonstrate that two orders of magnitude reduction in the neutron and photon fluxes can be obtained with appropriate shielding of critical forward regions such as the low beta quadrupoles and the forward calorimeter.

  7. Large dynamic range radiation detector and methods thereof

    DOEpatents

    Marrs, Roscoe E.; Madden, Norman W.

    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.

  8. Flame detector operable in presence of proton radiation

    NASA Technical Reports Server (NTRS)

    Walker, D. J.; Turnage, J. E.; Linford, R. M. F.; Cornish, S. D. (Inventor)

    1974-01-01

    A detector of ultraviolet radiation for operation in a space vehicle which orbits through high intensity radiation areas is described. Two identical ultraviolet sensor tubes are mounted within a shield which limits to acceptable levels the amount of proton radiation reaching the sensor tubes. The shield has an opening which permits ultraviolet radiation to reach one of the sensing tubes. The shield keeps ultraviolet radiation from reaching the other sensor tube, designated the reference tube. The circuitry of the detector subtracts the output of the reference tube from the output of the sensing tube, and any portion of the output of the sensing tube which is due to proton radiation is offset by the output of the reference tube. A delay circuit in the detector prevents false alarms by keeping statistical variations in the proton radiation sensed by the two sensor tubes from developing an output signal.

  9. A Xylophone Detector of Gravitational Radiation

    NASA Technical Reports Server (NTRS)

    Tinto, Massimo

    1997-01-01

    We discuss spacecraft Doppler tracking searches for 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 describe 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 technique provides also a way for reducing by several orders of magnitude, at selected Fourier components, the frequency fluctuations due to other noise sources, such as the clock on board the spacecraft or the antenna and buffeting of the probe by nongravitational forces. In this respect spacecraft Doppler tracking can be regarded as 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 x 10(exp -18) at 10(exp -3) Hz is estimated. This experimental technique could be extended to other tests of the theory of relativity, and to radio science experiments that rely on high-precision Doppler measurements.

  10. Alpha particle response study of polycrstalline diamond radiation detector

    NASA Astrophysics Data System (ADS)

    Kumar, Amit; Topkar, Anita

    2016-05-01

    Chemical vapor deposition has opened the possibility to grow high purity synthetic diamond at relatively low cost. This has opened up uses of diamond based detectors for wide range of applications. These detectors are most suitable for harsh environments where standard semiconductor detectors cannot work. In this paper, we present the fabrication details and performance study of polycrystalline diamond based radiation detector. Effect of different operating parameters such as bias voltage and shaping time for charge collection on the performance of detector has been studied.

  11. 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.

  12. A hybrid radiation detector based on a plasma display panel

    NASA Astrophysics Data System (ADS)

    Cho, Sungho; Lee, Rena; Yun, Min-Seok; Jang, Gi-Won; Park, Jikoon; Choi, Jang-Yong; Nam, Sanghee

    2009-10-01

    Recently, large-area image detectors have been investigated for X-ray imaging in medical diagnostic and other applications. In this paper, a new type of radiation detector is described, based on the integration of a photoconductor into a plasma display panel (PDP). This device, called a hybrid PDP detector, should be quite inexpensive, because it can directly leverage off the fabrication and materials technologies widely used in plasma display panels. Also, these new radiation detectors should operate under the most challenging environmental conditions, because they are inherently rugged and radiation-resistant and insensitive to magnetic fields. In this paper, we describe a hybrid digital radiation detector device, based on plasma display. The PDP panel is 7 in. in size with a 1000-μm pixel pitch, and filled with 700 Torr of Xe gas; the hybrid PDP panel is of the same structure, except for the photoconductor deposit. The glass absorption, dark current, X-ray sensitivity, and linearity as a function of electric field were measured to investigate its electrical properties. From the results, stabilized dark current density and significant X-ray sensitivity were obtained with both panels; however, the hybrid PDP detector showed better characteristics than the PDP detector. It also had good signal response and linearity. The hybrid digital radiation detector device based on a plasma display seems to be a promising technology for use in radiology and dynamic moving imaging.

  13. Chemical imaging of cotton fibers using an infrared microscope and a focal-plane array detector

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this presentation, the chemical imaging of cotton fibers with an infrared microscope and a Focal-Plane Array (FPA) detector will be discussed. Infrared spectroscopy can provide us with information on the structure and quality of cotton fibers. In addition, FPA detectors allow for simultaneous spe...

  14. Broadband ultrafast superconducting NbN detector for electromagnetic radiation

    NASA Astrophysics Data System (ADS)

    Gousev, Yu. P.; Gol'Tsman, G. N.; Semenov, A. D.; Gershenzon, E. M.; Nebosis, R. S.; Heusinger, M. A.; Renk, K. F.

    1994-04-01

    The paper shows that the NbN thin film detector combines, in an optimum way, both high sensitivity and short response, and it has, in addition, a broadband sensitivity from the submillimeter (or millimeter) wave range to visible light. Details of the experiment presents the performance and operating conditions of the broadband ultrafast superconducting NbN detector for electromagnetic radiation.

  15. Theory Of Radiation-Induced Attenuation In Optical Fibers

    NASA Technical Reports Server (NTRS)

    Liu, Tsuen-Hsi; Johnston, Alan R.

    1996-01-01

    Improved theory of radiation-induced attenuation of light in optical fibers accounts for effects of dose rates. Based on kinetic aspects of fundamental physics of color centers induced in optical fibers by radiation. Induced attenuation is proportional to density of color centers, and part of this density decays by thermal-annealing/recombination process after irradiation.

  16. Fiber-optic Cerenkov radiation sensor for proton therapy dosimetry.

    PubMed

    Jang, Kyoung Won; Yoo, Wook Jae; Shin, Sang Hun; Shin, Dongho; Lee, Bongsoo

    2012-06-18

    In proton therapy dosimetry, a fiber-optic radiation sensor incorporating a scintillator must undergo complicated correction processes due to the quenching effect of the scintillator. To overcome the drawbacks of the fiber-optic radiation sensor, we proposed an innovative method using the Cerenkov radiation generated in plastic optical fibers. In this study, we fabricated a fiber-optic Cerenkov radiation sensor without an organic scintillator to measure Cerenkov radiation induced by therapeutic proton beams. Bragg peaks and spread-out Bragg peaks of proton beams were measured using the fiber-optic Cerenkov radiation sensor and the results were compared with those of an ionization chamber and a fiber-optic radiation sensor incorporating an organic scintillator. From the results, we could obtain the Bragg peak and the spread-out Bragg peak of proton beams without quenching effects induced by the scintillator, and these results were in good agreement with those of the ionization chamber. We also measured the Cerenkov radiation generated from the fiber-optic Cerenkov radiation sensor as a function of the dose rate of the proton beam.

  17. Characterisation of bubble detectors for aircrew and space radiation exposure.

    PubMed

    Green, A R; Bennett, L G I; Lewis, B J; Tume, P; Andrews, H R; Noulty, R A; Ing, H

    2006-01-01

    The Earth's atmosphere acts as a natural radiation shield which protects terrestrial dwellers from the radiation environment encountered in space. In general, the intensity of this radiation field increases with distance from the ground owing to a decrease in the amount of atmospheric shielding. Neutrons form an important component of the radiation field to which the aircrew and spacecrew are exposed. In light of this, the neutron-sensitive bubble detector may be ideal as a portable personal dosemeter at jet altitudes and in space. This paper describes the ground-based characterisation of the bubble detector and the application of the bubble detector for the measurement of aircrew and spacecrew radiation exposure. PMID:16987919

  18. RADIATION EFFECTS ON EPOXY CARBON FIBER COMPOSITE

    SciTech Connect

    Hoffman, E

    2008-05-30

    Carbon fiber-reinforced bisphenol-A epoxy matrix composite was evaluated for gamma radiation resistance. The composite was exposed to total gamma doses of 50, 100, and 200 Mrad. Irradiated and baseline samples were tested for tensile strength, hardness and evaluated using FTIR (Fourier transform infrared) spectroscopy and DSC (differential scanning calorimetry) for structural changes. Scanning electron microscopy was used to evaluate microstructural behavior. Mechanical testing of the composite bars revealed no apparent change in modulus, strain to failure, or fracture strength after exposures. However, testing of only the epoxy matrix revealed changes in hardness, thermal properties, and FTIR results with increasing gamma irradiation. The results suggest the epoxy within the composite can be affected by exposure to gamma irradiation.

  19. Initial performance of the Wire Imaging Synchrotron Radiation Detector

    SciTech Connect

    Von Zanthier, C.; Gomez Cadenas, J.J.; Kent, J.; King, M.; Watson, S. ); Briggs, D.D.; Rouse, F.; Tinsman, J. )

    1990-01-01

    This paper describes the initial performance of a novel detector that measures the positions of intense synchrotron-radiation beams with high precision. Two detectors of this kind are used for the precision energy spectrometers of the Stanford Linear Collider (SLC). The detectors accurately determine the distance between pairs of intense synchrotron beams of typically 1 MeV photons, which are emitted by the primary electron and positron beams of the SLC. The detectors intercept the synchrotron beams with arrays of fine wires. The ejection of Compton-recoil electrons leaves positive charges on the wires, enabling a determination of beam positions. 6 refs., 6 figs.

  20. 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.

  1. RD50 Collaboration overview: Development of new radiation hard detectors

    NASA Astrophysics Data System (ADS)

    Kuehn, S.

    2016-07-01

    Silicon sensors are widely used as tracking detectors in high energy physics experiments. This results in several specific requirements like radiation hardness and granularity. Therefore research for highly performing silicon detectors is required. The RD50 Collaboration is a CERN R&D collaboration dedicated to the development of radiation hard silicon devices for application in high luminosity collider experiments. Extensive research is ongoing in different fields since 2001. The collaboration investigates both defect and material characterization, detector characterization, the development of new structures and full detector systems. The report gives selected results of the collaboration and places an emphasis on the development of new structures, namely 3D devices, CMOS sensors in HV technology and low gain avalanche detectors.

  2. Monolithic active pixel radiation detector with shielding techniques

    DOEpatents

    Deptuch, Grzegorz W.

    2016-09-06

    A monolithic active pixel radiation detector including a method of fabricating thereof. The disclosed radiation detector can include a substrate comprising a silicon layer upon which electronics are configured. A plurality of channels can be formed on the silicon layer, wherein the plurality of channels are connected to sources of signals located in a bulk part of the substrate, and wherein the signals flow through electrically conducting vias established in an isolation oxide on the substrate. One or more nested wells can be configured from the substrate, wherein the nested wells assist in collecting charge carriers released in interaction with radiation and wherein the nested wells further separate the electronics from the sensing portion of the detector substrate. The detector can also be configured according to a thick SOA method of fabrication.

  3. Pulsed radiation-induced attenuation in certain optical fibers

    SciTech Connect

    Weiss, J.D. )

    1992-05-01

    Using the X-ray pulse from the HERMES II simulation machine at Sandia National Laboratories, the pulsed radiation-induced attenuation was measured in two optical fibers considered to be 'nonrad-hard': the 50-micron-core, graded-index fiber from Corning and the plastic (PMMA) fiber from the Mitsubishi Rayon Company. These fibers were exposed to radiation up to doses of 19.5 and 28 krad(Si), respectively. In addition, fits of their post-radiation recovery were made to the geminate recombination model, from which the recombination-rate and generation constants, characteristic of this theory, were determined. These parameters should be useful in determining the response of the fibers to radiation conditions other than those encountered here. 18 refs.

  4. Radioactivity measurement of radioactive contaminated soil by using a fiber-optic radiation sensor

    NASA Astrophysics Data System (ADS)

    Joo, Hanyoung; Kim, Rinah; Moon, Joo Hyun

    2016-06-01

    A fiber-optic radiation sensor (FORS) was developed to measure the gamma radiation from radioactive contaminated soil. The FORS was fabricated using an inorganic scintillator (Lu,Y)2SiO5:Ce (LYSO:Ce), a mixture of epoxy resin and hardener, aluminum foil, and a plastic optical fiber. Before its real application, the FORS was tested to determine if it performed adequately. The test result showed that the measurements by the FORS adequately followed the theoretically estimated values. Then, the FORS was applied to measure the gamma radiation from radioactive contaminated soil. For comparison, a commercial radiation detector was also applied to measure the same soil samples. The measurement data were analyzed by using a statistical parameter, the critical level to determine if net radioactivity statistically different from background was present in the soil sample. The analysis showed that the soil sample had radioactivity distinguishable from background.

  5. Nuclear radiation-warning detector that measures impedance

    SciTech Connect

    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. Fiber scintillator/streak camera detector for burn history measurement in inertial confinement fusion experiment

    SciTech Connect

    Miyanaga, N.; Ohba, N.; Fujimoto, K.

    1997-01-01

    To measure the burn history in an inertial confinement fusion experiment, we have developed a new neutron detector based on plastic scintillation fibers. Twenty-five fiber scintillators were arranged in a geometry compensation configuration by which the time-of-flight difference of the neutrons is compensated by the transit time difference of light passing through the fibers. Each fiber scintillator is spliced individually to an ultraviolet optical fiber that is coupled to a streak camera. We have demonstrated a significant improvement of sensitivity compared with the usual bulk scintillator coupled to a bundle of the same ultraviolet fibers. {copyright} {ital 1997 American Institute of Physics.}

  8. Development of a small scintillation detector with an optical fiber for fast neutrons.

    PubMed

    Yagi, T; Unesaki, H; Misawa, T; Pyeon, C H; Shiroya, S; Matsumoto, T; Harano, H

    2011-02-01

    To investigate the characteristics of a reactor and a neutron generator, a small scintillation detector with an optical fiber with ThO(2) has been developed to measure fast neutrons. However, experimental facilities where (232)Th can be used are limited by regulations, and S/N ratio is low because the background counts of this detector are increase by alpha decay of (232)Th. The purpose of this study is to develop a new optical fiber detector for measuring fast neutrons that does not use nuclear material such as (232)Th. From the measured and calculated results, the new optical fiber detector which uses ZnS(Ag) as a converter material together with a scintillator have the highest detection efficiency among several developed detectors. It is applied for the measurement of reaction rates generated from fast neutrons; furthermore, the absolute detection efficiency of this detector was obtained experimentally.

  9. Thermoluminescence characteristics of Ge-doped optical fibers with different dimensions for radiation dosimetry.

    PubMed

    Begum, Mahfuza; Rahman, A K M Mizanur; Abdul-Rashid, H A; Yusoff, Z; Begum, Mahbuba; Mat-Sharif, K A; Amin, Y M; Bradley, D A

    2015-06-01

    Important thermoluminescence (TL) properties of five (5) different core sizes Ge-doped optical fibers have been studied to develop new TL material with better response. These are drawn from same preform applying different speed and tension during drawing phase to produce Ge-doped optical fibers with five (5) different core sizes. The results of the investigations are also compared with most commonly used standard TLD-100 chips (LiF:Mg,Ti) and commercial multimode Ge-doped optical fiber (Yangtze Optical Fiber, China). Scanning Electron Microscope (SEM) and EDX analysis of the fibers are also performed to map Ge distribution across the deposited region. Standard Gamma radiation source in Secondary Standard Dosimetry Lab (SSDL) was used for irradiation covering dose range from 1Gy to 10Gy. The essential dosimetric parameters that have been studied are TL linearity, reproducibility and fading. Prior to irradiation all samples ∼0.5cm length are annealed at temperature of 400°C for 1h period to standardize their sensitivities and background. Standard TLD-100 chips are also annealed for 1h at 400°C and subsequently 2h at 100°C to yield the highest sensitivity. TL responses of these fibers show linearity over a wide gamma radiation dose that is an important property for radiation dosimetry. Among all fibers used in this study, 100μm core diameter fiber provides highest response that is 2.6 times than that of smallest core (20μm core) optical fiber. These fiber-samples demonstrate better response than commercial multi-mode optical fiber and also provide low degree of fading about 20% over a period of fifteen days for gamma radiation. Effective atomic number (Zeff) is found in the range (13.25-13.69) which is higher than soft tissue (7.5) however within the range of human-bone (11.6-13.8). All the fibers can also be re-used several times as a detector after annealing. TL properties of the Ge-doped optical fibers indicate promising applications in ionizing radiation

  10. Operation of silicon microstrip detectors in a high radiation environment

    SciTech Connect

    Kapustinsky, J.S.; Alde, D.M.; Boissevain, J.G.; Jeppesen, R.G.; Lane, D.W.; Leitch, M.J.; Lillberg, J.W.; Lopez, T.A.; McGaughey, P.L.; Moss, J.M.; Peng, J.C. ); Brooks, B.M.; Isenhower, L.D.; Sadler, M.E. ); Lederman, L.M.; Schub, M.H. ); Brown, C.N.; Cooper, W.E.; Gounder, K.; Hsiung, Y.B.; Mishra, C.S. (Fermi National

    1990-01-01

    A Silicon Microstrip Spectrometer was recently installed and operated in an 800 GeV proton beamline at Fermilab as a major new component of experiment E789. The detectors received an estimated radiation exposure of up to 7.8 {times} 10{sup 12} minimum ionizing particles per cm{sup 2} over a period of two months. We report on the changes in detector performance that we have observed following preliminary data analysis. 5 refs., 4 figs.

  11. 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.

  12. The photon detector of the HERMES dual-radiator RICH

    NASA Astrophysics Data System (ADS)

    Aschenauer, E. C.; Van der Kerckhove, K.

    1999-08-01

    To provide hadron identification over the full kinematic range (2-20GeV) of the HERMES experiment, the gas threshold Cherenkov counters were replaced by a dual-radiator ring-imaging Cherenkov detectors incorporating for the first time aerogel (SiO2) and C4F10 gas as radiator materials. This combination of radiators requires a photon detector that is sensitive over wavelengths from ultraviolet to 700nm. Commercially available `3/4 in.' photo-multipliers were chosen to form an array of 2000 for each of two photon-detectors. Exhaustive calibration and sorting of the phototubes prior to installation resulted in very low noise hit rates in the LeCroy PCOS4 readout system, with a uniform effective threshold of 0.1 photo-electrons.

  13. Three-axis asymmetric radiation detector system

    DOEpatents

    Martini, Mario Pierangelo; Gedcke, Dale A.; Raudorf, Thomas W.; Sangsingkeow, Pat

    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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. A Silicon detector system on carbon fiber support at small radius

    SciTech Connect

    Marvin E. Johnson

    2004-04-28

    The design of a silicon detector for a p{bar p} collider experiment will be described. The detector uses a carbon fiber support structure with sensors positioned at small radius with respect to the beam. A brief overview of the mechanical design is given. The emphasis is on the electrical characteristics of the detector. General principles involved in grounding systems with carbon fiber structures will be covered. The electrical characteristics of the carbon fiber support structure will be presented. Test results imply that carbon fiber must be regarded as a conductor for the frequency region of interest of 10 to 100 MHz. No distinction is found between carbon fiber and copper. Performance results on noise due to pick-up through the low mass fine pitch cables carrying the analogue signals and floating metal is discussed.

  19. Accuracy of Analog Fiber-Optic Links in Pulsed Radiation Environments

    SciTech Connect

    E. K. Miller, G. S. Macrum, I. J. McKenna, et al.

    2007-12-01

    second case, we present data using a state-of-the-art fiber-optic link for single-shot transmission and recording, fielded at the OMEGA laser facility on high-yield fusion experiments. Gamma reaction history data are measured with a gas Cherenkov detector (GCD) [4], [5] and transmitted by M-Z link to a 12 GHz digitizer. Since radiation effects on the fibers are not above the noise floor, the error analysis for the unfolded data is dominated by the performance of the fast digitizer, the photoreceiver, and the laser.

  20. (Effects of ionizing radiation on scintillators and other particle detectors)

    SciTech Connect

    Proudfoot, J.

    1992-01-01

    It is my task to summarise the great variety of topics (covering a refreshing mix of physics, chemistry and technology) presented at this conference, which has focused on the effects of ionising radiation on scintillators and other particle detectors. One of the reasons and the central interest of many of the participants was the use of such detectors in experiments at two future large hadron colliders: the Superconducting Super Collider to be operating outside of Dallas in the United States by the turn of the decade and its European counterpart the Large Hadron Collider to be operating outside of Geneva in Switzerland on a similar time scale. These accelerators are the apple of the high energy physicist's eye.'' Their goal is to uncover the elusive Higgs particle and thereby set the cornerstone in our current knowledge of elementary particle interactions. This is the Quest, and from this lofty height the presentations rapidly moved on to the specific questions of experimental science: how such an experiment is carried out; why radiation damage is an issue; how radiation damage affects detectors; which factors affect radiation damage characteristics; which factors are not affected by radiation damage; and how better detectors may be constructed. These were the substance of this conference.

  1. Semiconductor radiation detector with internal gain

    DOEpatents

    Iwanczyk, Jan; Patt, Bradley E.; Vilkelis, Gintas

    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.

  2. Recent progress in the transition radiation detector techniques

    NASA Technical Reports Server (NTRS)

    Yuan, L. C. L.

    1973-01-01

    A list of some of the major experimental achievements involving charged particles in the relativistic region are presented. With the emphasis mainly directed to the X-ray region, certain modes of application of the transition radiation for the identification and separation of relativistic charged particles are discussed. Some recent developments in detection techniques and improvements in detector performances are presented. Experiments were also carried out to detect the dynamic radiation, but no evidence of such an effect was observed.

  3. Effects of gamma radiation on perfluorinated polymer optical fibers

    NASA Astrophysics Data System (ADS)

    Stajanca, Pavol; Mihai, Laura; Sporea, Dan; Neguţ, Daniel; Sturm, Heinz; Schukar, Marcus; Krebber, Katerina

    2016-08-01

    The paper presents the first complex study of gamma radiation effects on a low-loss perfluorinated polymer optical fiber (PF-POF) based on Cytop® polymer. Influence of gamma radiation on fiber's optical, mechanical and climatic performance is investigated. The radiation-induced attenuation (RIA) in the visible and near-infrared region (0.4 μm-1.7 μm) is measured and its origins are discussed. Besides attenuation increase, radiation is also shown to decrease the thermal degradation stability of the fiber and to increase its susceptibility to water. With regard to complex fiber transmission performance upon irradiation, the optimal operation wavelength region of PF-POF-based systems intended for use in radiation environments is determined to be around 1.1 μm. On the other hand, the investigated fiber holds potential for low-cost RIA-based optical fiber dosimetry applications with sensitivity as high as 260 dBm-1/kGy in the visible region.

  4. Radiation Response of Emerging High Gain, Low Noise Detectors

    NASA Technical Reports Server (NTRS)

    Becker, Heidi N.; Farr, William H; Zhu, David Q.

    2007-01-01

    Data illustrating the radiation response of emerging high gain, low noise detectors are presented. Ionizing dose testing of silicon internal discrete avalanche photodiodes, and 51-MeV proton testing of InGaAs/InAlAs avalanche photodiodes operated in Geiger mode are discussed.

  5. 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.

  6. Liquid cooled fiber thermal radiation receiver

    DOEpatents

    Butler, Barry L.

    1987-01-01

    A radiation-to-thermal receiver apparatus for collecting radiation and converting it to thermal energy is disclosed. The invention includes a fibrous mat material which captures radiation striking the receiver. Captured radiation is removed from the fibrous mat material by a transparent fluid within which the material is bathed.

  7. Liquid cooled fiber thermal radiation receiver

    DOEpatents

    Butler, B.L.

    1985-03-29

    A radiation-to-thermal receiver apparatus for collecting radiation and converting it to thermal energy is disclosed. The invention includes a fibrous mat material which captures radiation striking the receiver. Captured radiation is removed from the fibrous mat material by a transparent fluid within which the material is bathed.

  8. 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.

  9. Three-dimensional architecture for solid state radiation detectors

    DOEpatents

    Parker, Sherwood

    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.

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

    SciTech Connect

    Mueller, G M

    1984-01-01

    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/h to 20 mR/h. This report discusses the cause of ailure, detector radiation measurement characteristics, and our estimates of the total gamma radiation dose received by the detector electronics.

  11. 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.

  12. 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.

  13. Fiber-coupled quantum-communications receiver based on two NbN superconducting single-photon detectors

    NASA Astrophysics Data System (ADS)

    Slysz, W.; Wegrzecki, M.; Bar, J.; Grabiec, P.; Górska, M.; Latta, C.; Zwiller, V.; Pearlman, A.; Cross, A.; Korneev, A.; Kouminov, P.; Smirnov, K.; Voronov, B.; Gol'tsman, G.; Verevkin, A.; Currie, M.; Sobolewski, R.

    2005-09-01

    We present the design and performance of a novel, two-channel single-photon receiver, based on two fiber-coupled NbN superconducting single-photon detectors (SSPDs). The SSPDs are nanostructured superconducting meanders covering an area of 100 μm2 and are known for ultrafast and efficient counting of single, visible-to-infrared photons. Their operation has been explained within a phenomenological hot-electron photoresponse model. Our receiver is intended for fiber-based quantum cryptography and communication systems, operational at near-infrared (NIR) telecommunication wavelengths, λ = 1.3 μm and λ = 1.55 μm. Coupling between the NbN detector and a single-mode optical fiber was achieved using a specially designed, micromechanical photoresist ring, positioned directly over the SSPD active area. The positioning accuracy of the ring was below 1 μm. The receiver with SSPDs was placed (immersed) in a standard liquid-helium transport Dewar and kept without interruption for over two months at 4.2 K. At the same time, the optical fiber inputs and electrical outputs were kept at room temperature. Our best system reached a system quantum efficiency of up to 0.3 % in the NIR radiation range, with the detector coupling efficiency of about 30 %. The response time was measured to be about 250 ps and was limited by our read-out electronics. The measured jitter was close to 35 ps. The presented performance parameters show that our NIR single photon detectors are suitable for practical quantum cryptography and for applications in quantum-correlation experiments.

  14. Improved spectrometric characteristics of thallium bromide nuclear radiation detectors

    NASA Astrophysics Data System (ADS)

    Hitomi, K.; Murayama, T.; Shoji, T.; Suehiro, T.; Hiratate, Y.

    1999-06-01

    Thallium bromide (TlBr) is a compound semiconductor with a high atomic number and wide band gap. In this study, nuclear radiation detectors have been fabricated from the TlBr crystals. The TlBr crystals were grown by the horizontal travelling molten zone (TMZ) method using the materials purified by many pass zone refining. The crystals were characterized by measuring the resistivity, the mobility-lifetime ( μτ) product and the energy required to create an electron-hole pair (the ɛ value). Improved energy resolution has been obtained by the TlBr radiation detectors. At room temperature the full-width at half-maximum (FWHM) for the 59.5, 122 and 662 keV γ-ray photo peak obtained from the detectors were 3.3, 8.8 and 29.5 keV, respectively. By comparing the saturated peak position of the TlBr detector with that of the CdTe detector, the ɛ value has been estimated to be about 5.85 eV for the TlBr crystal.

  15. 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.

  16. Test of radiation detectors used in homeland security applications.

    PubMed

    Pibida, L; Minniti, R; O'Brien, M; Unterweger, M

    2005-05-01

    This work was performed as part of the National Institute of Standards and Technology (NIST) program to support the development of the new American National Standards Institute (ANSI) standards N42.32-2003 and N42.33-2003 for hand-held detectors, and personal electronic dosimeters, as well as to support the Office of Law Enforcement Standards (OLES) and the Department of Homeland Security (DHS) in testing these types of detectors for their use by first responders. These instruments are required to operate over a photon energy range of 60 keV to 1.33 MeV and over a wide range of air-kerma rates. The performance and response of various radiation detectors, purchased by the NIST, was recorded when placed in 60Co, 137Cs, and x-ray beams at different air-kerma rates. The measurements described in this report were performed at the NIST x-ray and gamma-ray radiation calibration facilities. The instruments' response (exposure or dose rate readings) shows strong energy dependence but almost no dependence to different air-kerma rates. The data here reported provide a benchmark in support of current protocols that are being developed for radiation detection instrumentation used in homeland security applications. A future plan is to test these devices, plus other commercially available detectors, against ANSI standards N42.32-2003 and N42.33-2003.

  17. GaN as a radiation hard particle detector

    NASA Astrophysics Data System (ADS)

    Grant, J.; Bates, R.; Cunningham, W.; Blue, A.; Melone, J.; McEwan, F.; Vaitkus, J.; Gaubas, E.; O'Shea, V.

    2007-06-01

    Semiconductor tracking detectors at experiments such as ATLAS and LHCb at the CERN Large Hadron Collider (LHC) will be subjected to intense levels of radiation. The proposed machine upgrade, the Super-LHC (SLHC), to 10 times the initial luminosity of the LHC will require detectors that are ultra-radiation hard. Much of the current research into finding a detector that will meet the requirements of the SLHC has focused on using silicon substrates with enhanced levels of oxygen, for example Czochralski silicon and diffusion oxygenated float zone silicon, and into novel detector structures such as 3D devices. Another avenue currently being investigated is the use of wide band gap semiconductors such as silicon carbide (SiC) and gallium nitride (GaN). Both SiC and GaN should be intrinsically more radiation hard than silicon. Pad and guard ring structures were fabricated on three epitaxial GaN wafers. The epitaxial GaN thickness was either 2.5 or 12 μm and the fabricated detectors were irradiated to various fluences with 24 GeV/c protons and 1 MeV neutrons. Detectors were characterised pre- and post-irradiation by performing current-voltage ( I- V) and charge collection efficiency (CCE) measurements. Devices fabricated on 12 μm epitaxial GaN irradiated to fluences of 1016 protons cm-2 and 1016 neutrons cm-2 show maximum CCE values of 26% and 20%, respectively, compared to a maximum CCE of 53% of the unirradiated device.

  18. Operating point stabilization of fiber-based line detectors for photoacoustic imaging

    NASA Astrophysics Data System (ADS)

    Felbermayer, Karoline; Grün, Hubert; Berer, Thomas; Burgholzer, Peter

    2011-07-01

    Photoacoustic imaging is an upcoming technique in the field of biomedical imaging. Our group introduced fiber-based line detectors, which are used to acquire broad-band ultrasonic signals, several years ago. Up to now operating point stabilization of fiber-based line detectors was realized by tuning the wavelength of the detection laser. This is, because of the high costs, not applicable for parallel detection. An alternative stabilization method, the change of the optical path length, is presented in this paper. Changing of the optical path length is realized by stretching the fiber with piezoelectric tubes. Fringe patterns and operation point stabilization of both stabilization schemes are compared. Next, signal detection utilizing a polymer optical fiber in a Mach-Zehnder and Fabry-Perot interferometer is demonstrated, and the influence of the detection wavelength (633nm and 1550nm) is examined. Finally, two-dimensional imaging by utilizing a perfluorinated polymer fiber is demonstrated.

  19. Spectroscopic separation of Čerenkov radiation in high-resolution radiation fiber dosimeters

    NASA Astrophysics Data System (ADS)

    Darafsheh, Arash; Zhang, Rongxiao; Kanick, Stephen Chad; Pogue, Brian W.; Finlay, Jarod C.

    2015-09-01

    We have investigated Čerenkov radiation generated in phosphor-based optical fiber dosimeters irradiated with clinical electron beams. We fabricated two high-spatial resolution fiber-optic probes, with 200 and 400 μm core diameters, composed of terbium-based phosphor tips. A generalizable spectroscopic method was used to separate Čerenkov radiation from the transmitted signal by the fiber based on the assumption that the recorded signal is a linear superposition of two basis spectra: characteristic luminescence of the phosphor medium and Čerenkov radiation. We performed Monte Carlo simulations of the Čerenkov radiation generated in the fiber and found a strong dependence of the recorded Čerenkov radiation on the numerical aperture of the fiber at shallow phantom depths; however, beyond the depth of maximum dose that dependency is minimal. The simulation results agree with the experimental results for Čerenkov radiation generated in fibers. The spectroscopic technique used in this work can be used for development of high-spatial resolution fiber micro dosimeters and for optical characterization of various scintillating materials, such as phosphor nanoparticles, in ionizing radiation fields of high energy.

  20. Direct measurement of instantaneous source speed for a HDR brachytherapy unit using an optical fiber based detector

    SciTech Connect

    Minamisawa, R. A.; Rubo, R. A.; Seraide, R. M.; Rocha, J. R. O.; Almeida, A.

    2010-10-15

    Purpose: Several attempts to determine the transit time of a high dose rate (HDR) brachytherapy unit have been reported in the literature with controversial results. The determination of the source speed is necessary to accurately calculate the transient dose in brachytherapy treatments. In these studies, only the average speed of the source was measured as a parameter for transit dose calculation, which does not account for the realistic movement of the source, and is therefore inaccurate for numerical simulations. The purpose of this work is to report the implementation and technical design of an optical fiber based detector to directly measure the instantaneous speed profile of a {sup 192}Ir source in a Nucletron HDR brachytherapy unit. Methods: To accomplish this task, we have developed a setup that uses the Cerenkov light induced in optical fibers as a detection signal for the radiation source moving inside the HDR catheter. As the {sup 192}Ir source travels between two optical fibers with known distance, the threshold of the induced signals are used to extract the transit time and thus the velocity. The high resolution of the detector enables the measurement of the transit time at short separation distance of the fibers, providing the instantaneous speed. Results: Accurate and high resolution speed profiles of the {sup 192}Ir radiation source traveling from the safe to the end of the catheter and between dwell positions are presented. The maximum and minimum velocities of the source were found to be 52.0{+-}1.0 and 17.3{+-}1.2 cm/s. The authors demonstrate that the radiation source follows a uniformly accelerated linear motion with acceleration of |a|=113 cm/s{sup 2}. In addition, the authors compare the average speed measured using the optical fiber detector to those obtained in the literature, showing deviation up to 265%. Conclusions: To the best of the authors' knowledge, the authors directly measured for the first time the instantaneous speed profile of

  1. 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 α-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/μm.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Radiation Tolerance of Aluminum Microwave Kinetic Inductance Detector

    NASA Astrophysics Data System (ADS)

    Karatsu, K.; Dominjon, A.; Fujino, T.; Funaki, T.; Hazumi, M.; Irie, F.; Ishino, H.; Kida, Y.; Matsumura, T.; Mizukami, K.; Naruse, M.; Nitta, T.; Noguchi, T.; Oka, N.; Sekiguchi, S.; Sekimoto, Y.; Sekine, M.; Shu, S.; Yamada, Y.; Yamashita, T.

    2016-08-01

    Microwave kinetic inductance detector (MKID) is one of the candidates of focal plane detector for future satellite missions such as LiteBIRD. For the space use of MKIDs, the radiation tolerance is one of the challenges to be characterized prior to the launch. Aluminum (Al) MKIDs with 50 nm thickness on silicon substrate and on sapphire substrate were irradiated with a proton beam of 160 MeV at the heavy ion medical accelerator in Chiba. The total water-equivalent absorbed dose was ˜ 10 krad which should simulate the worst radiation absorption of 5 years observation at the Lagrange point L2. We measured characteristics of these MKIDs before and after the irradiation. We found no significant changes on resonator quality factor, responsivity, and recombination time of quasi-particles. The change on electrical noise equivalent power was also evaluated, and no significant increase was found at the noise level of O(10^{-18}) W/√{ Hz }.

  7. Studying radiation hardness of a cadmium tungstate crystal based radiation detector

    NASA Astrophysics Data System (ADS)

    Shtein, M. M.; Smekalin, L. F.; Stepanov, S. A.; Zatonov, I. A.; Tkacheva, T. V.; Usachev, E. Yu

    2016-06-01

    The given article considers radiation hardness of an X-ray detector used in production of non-destructive testing instruments and inspection systems. In the course of research, experiments were carried out to estimate radiation hardness of a detector based on cadmium tungstate crystal and its structural components individually. The article describes a layout of an experimental facility that was used for measurements of radiation hardness. The radiation dose dependence of the photodiode current is presented, when it is excited by a light flux of a scintillator or by an external light source. Experiments were carried out to estimate radiation hardness of two types of optical glue used in detector production; they are based on silicon rubber and epoxy. With the help of a spectrophotometer and cobalt gun, each of the glue samples was measured for a relative light transmission factor with different wavelengths, depending on the radiation dose. The obtained data are presented in a comprehensive analysis of the results. It was determined, which of the glue samples is most suitable for production of detectors working under exposure to strong radiation.

  8. 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.

  9. 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.

  10. Radiation monitoring of the GEM muon detectors at CMS

    NASA Astrophysics Data System (ADS)

    Dimitrov, L.; Iaydjiev, P.; Mitev, G.; Vankov, I.

    2016-09-01

    The higher energy and luminosity of future High Luminosity (HL) LHC, determines a significant increasing of the radiation background around the CMS subdetectors, and especially in the higher pseudorapidity region. Under such heavy conditions, the RPC (used in muon trigger) most probably could not operate effectively. GEM (Gas Electron Multiplier) detectors have been identified as a suitable technology to operate in the high radiation environment in that region and test at CMS will start in 2016. A monitoring system to control the absorbed radiation dose by the GEM under test is developed. Two types of sensors are used in it: RadFETs for total absorbed dose and p-i-n diodes for particle (proton and neutron) detection. The basic detector unit, called RADMON, contains two sensors of each type and can be installed at each GEM detector. The system has a modular structure, permitting to increase easily the number of controlled RADMONs: one module controls up to 12 RADMONs, organized in three group of four and communicates outside by RS 485 and CANBUS interfaces.

  11. A transition radiation detector for kaon/pion separation

    NASA Astrophysics Data System (ADS)

    Baake, M.; Diekmann, B.; Gebert, F.; Heinloth, K.; Holzkamp, S.; Körsgen, G.; Voigtlaender-Tetzner, A.; Bagdassarian, L.; Kazarian, C.; Oganessian, A.

    1989-09-01

    The experiment WA69 at the CERN Omega spectrometer facility has studied fixed target photon and hadron production of inclusive hadronic final states with tagged photon beams of 65-175 GeV in comparison to charged hadron beams (π and K) of 80 and 140 GeV fixed energies. For the identification of final state pions and kaons above 100 GeV/c a transition radiation detector (TRAD) has been developed. This detector was constructed of 12 modules, each consisting of a polypropylene fibre radiator and a proportional chamber with a xenon/methane gas mixture to detect the transition radiation produced by fast moving charged particles. We give a description of the detector setup and working conditions. As a first result obtained with the TRAD the ratio of photoproduced kaons and pions in the extreme forward regime ( xF > 0.7 and - t < 1 GeV 2) is measured to be 10.2(±1.7)% which is in agreement with VDM predictions.

  12. A Voltage-Tunable Quantum Well Detector for Terahertz Radiation

    NASA Astrophysics Data System (ADS)

    Briceño, G.; Williams, J. B.; Sherwin, M. S.; Campman, K.; Gossard, A. C.

    1997-03-01

    Intersubband transitions in quantum wells have enabled the development of sensitive quantum well infrared photoconductors (QWIP) at wavelengths shorter than 20 microns. The potential of quantum well-based detectors at wavelengths of order 100 microns (3 Terahertz (THz)) has not been realized. We propose a novel antenna-coupled intersubband detector for THz frequencies. The detector is predicted to be sensitive only in a narrow band of frequencies which can be tuned by a factor of order two by applying dc voltages of order 1V. The speed of the detector is predicted to be limited by the intersubband relaxation rate (1 ns at T=10K)(J. N. Heyman et. al., Phys. Rev. Lett. 74), 2682 (1995). Prototype detectors have been constructed. The structure, dc transport characteristics and response of these devices to THz radiation will be discussed. Supported by the NSF Science and Technology Center for Quantized Electronic Structures DMR 91-20007, NSF DMR 9623874, AFOSR F-49620-94-1-0158, and the Ford Foundation (GB).

  13. PARROT A fiber optic link for particle detectors

    NASA Astrophysics Data System (ADS)

    Leone, Maurizio; Trasatti, Luciano; Stefani, Giovanni; Avaldi, Lorenzo

    1993-09-01

    The fiber optic technology has been used to build a transmitter-receiver system capable of delivering channeltron or PM tube signals through a few hundred meter span. The intrinsic immunity of optical fibers to e.m. noise has been used to reduce noise problems in an experimental apparatus equipped with two electrostatic analyzers for coincidence (e, 2e) spectroscopy. A coincidence energy separation spectrum of He, used for calibration of the apparatus energy scale, has been measured using fiber optic links instead of coaxial cables. The system was completely built using cheap and easily available commercial components. The results show that fiber optic links could become a viable technique for noise reduction, high voltage decoupling and low temperature calorimeters signal transfer.

  14. Degradation of silicon ac-coupled microstrip detectors induced by radiation

    SciTech Connect

    Bacchetta, N.; Gotra, Yu.; Bisello, D. |; Canali, C.; Fuochi, P.G.; Paccagnella, A.; Verzellesi, G. |

    1993-12-01

    Results are presented showing the radiation response of ac-coupled FOXFET biased microstrip detectors and related test patterns to be used in the microvertex detector of the CDF experiment at Fermi National Laboratory. Radiation tolerance of detectors to gamma and proton irradiation has been tested and the radiation induced variations of the dc electrical parameters have been analyzed. Long term post-irradiation behavior of detector characteristics have been studied, and the relevant room temperature annealing phenomena have been discussed.

  15. [Influence of Detector Radiation Damage on CR Mammography Quality Control].

    PubMed

    Moriwaki, Atsumi; Ishii, Mie; Terazono, Shiho; Arao, Keiko; Ishii, Rie; Sanada, Taizo; Yoshida, Akira

    2016-05-01

    Recently, radiation damage to the detector apparatus employed in computed radiography (CR) mammography has become problematic. The CR system and the imaging plate (IP) applied to quality control (QC) program were also used in clinical mammography in our hospital, and the IP to which radiation damage has occurred was used for approximately 5 years (approximately 13,000 exposures). We considered using previously acquired QC image data, which is stored in a server, to investigate the influence of radiation damage to an IP. The mammography unit employed in this study was a phase contrast mammography (PCM) Mermaid (KONICA MINOLTA) system. The QC image was made newly, and it was output in the film, and thereafter the optical density of the step-phantom image was measured. An input (digital value)-output (optical density) conversion curve was plotted using the obtained data. The digital values were then converted to optical density values using a reference optical density vs. digital value curve. When a high radiation dose was applied directly, radiation damage occurred at a position on the IP where no object was present. Daily QC for mammography is conducted using an American College of Radiology (ACR) accreditation phantom and acrylic disc, and an environmental background density measurement is performed as one of the management indexes. In this study, the radiation damage sustained by the acrylic disc was shown to differ from that of the background. Thus, it was revealed that QC results are influenced by radiation damage. PMID:27211088

  16. Photoacoustic projection imaging using a 64-channel fiber optic detector array

    NASA Astrophysics Data System (ADS)

    Bauer-Marschallinger, Johannes; Felbermayer, Karoline; Bouchal, Klaus-Dieter; Veres, Istvan A.; Grün, Hubert; Burgholzer, Peter; Berer, Thomas

    2015-03-01

    In this work we present photoacoustic projection imaging with a 64-channel integrating line detector array, which average the pressure over cylindrical surfaces. For imaging, the line detectors are arranged parallel to each other on a cylindrical surface surrounding a specimen. Thereby, the three-dimensional imaging problem is reduced to a twodimensional problem, facilitating projection imaging. After acquisition of a dataset of pressure signals, a twodimensional photoacoustic projection image is reconstructed. The 64 channel line detector array is realized using optical fibers being part of interferometers. The parts of the interferometers used to detect the ultrasonic pressure waves consist of graded-index polymer-optical fibers (POFs), which exhibit better sensitivity than standard glass-optical fibers. Ultrasonic waves impinging on the POFs change the phase of light in the fiber-core due to the strain-optic effect. This phase shifts, representing the pressure signals, are demodulated using high-bandwidth balanced photo-detectors. The 64 detectors are optically multiplexed to 16 detection channels, thereby allowing fast imaging. Results are shown on a Rhodamine B dyed microsphere.

  17. 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.

  18. 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

  19. Novel semiconductor radiation detector based on mercurous halides

    NASA Astrophysics Data System (ADS)

    Chen, Henry; Kim, Joo-Soo; Amarasinghe, Proyanthi; Palosz, Withold; Jin, Feng; Trivedi, Sudhir; Burger, Arnold; Marsh, Jarrod C.; Litz, Marc S.; Wiejewarnasuriya, Priyalal S.; Gupta, Neelam; Jensen, Janet; Jensen, James

    2015-08-01

    The three most important desirable features in the search for room temperature semiconductor detector (RTSD) candidate as an alternative material to current commercially off-the-shelf (COTS) material for gamma and/or thermal neutron detection are: low cost, high performance and long term stability. This is especially important for pager form application in homeland security. Despite years of research, no RTSD candidate so far can satisfy the above 3 features simultaneously. In this work, we show that mercurous halide materials Hg2X2 (X= I, Cl, Br) is a new class of innovative compound semiconductors that is capable of delivering breakthrough advances to COTS radiation detector materials. These materials are much easier to grow thicker and larger volume crystals. They can detect gamma and potentially neutron radiation making it possible to detect two types of radiation with just one crystal material. The materials have wider bandgaps (compared to COTS) meaning higher resistivity and lower leakage current, making this new technology more compatible with available microelectronics. The materials also have higher atomic number and density leading to higher stopping power and better detector sensitivity/efficiency. They are not hazardous so there are no environmental and health concerns during manufacturing and are more stable making them more practical for commercial deployment. Focus will be on Hg2I2. Material characterization and detector performance will be presented and discussed. Initial results show that an energy resolution better than 2% @ 59.6 keV gamma from Am-241 and near 1% @ 662 keV from Cs-137 source can be achieved at room temperature.

  20. 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.

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

    DOEpatents

    Miller, William H.; Berliner, Ronald R.

    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.

  2. Fiber-Optic Micrometeoroid/Orbital Debris Impact Detector System

    NASA Technical Reports Server (NTRS)

    Christiansen, Eric L.; Tennyson, R. C.; Morison, W. D.

    2012-01-01

    A document describes a reliable, lightweight micrometeoroid/orbital debris (MMOD) detection system that can be located at strategic positions of "high consequence" to provide real-time warning of a penetration, its location, and the extent of the damage to a spacecraft. The concept is to employ fiber-optic sensors to detect impact damage and penetration of spacecraft structures. The fibers are non-electrical, employ light waves, and are immune to electromagnetic interference. The fiber-optic sensor array can be made as a stand-alone product, being bonded to a flexible membrane material or a structure that is employed as a MMOD shield material. The optical sensors can also be woven into hybrid MMOD shielding fabrics. The glass fibers of the fiber-optic sensor provide a dual purpose in contributing to the breakup of MMOD projectiles. The grid arrays can be made in a modular configuration to provide coverage over any area desired. Each module can be connected to a central scanner instrument and be interrogated in a continuous or periodic mode.

  3. 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.

  4. Ce{sup 3+}-doped fibers for remote radiation dosimetry

    SciTech Connect

    Vedda, A.; Chiodini, N.; Di Martino, D.; Fasoli, M.; Keffer, S.; Lauria, A.; Martini, M.; Moretti, F.; Spinolo, G.; Nikl, M.; Solovieva, N.; Brambilla, G.

    2004-12-27

    A radioluminescent (RL) dosimetric system, based on a SiO{sub 2} optical fiber with the core doped by Ce{sup 3+} ions as luminescent activators has been investigated. Structural and optical properties of the luminescent fiber have been studied by Raman, refractive index, RL and scintillation time decay measurements, and compared to those obtained on bulk material. The RL response of a composite fiber made of a short portion of active Ce-doped fiber coupled to a long commercial one has been investigated by x-ray irradiation. A linear RL intensity response has been found in the dose rate interval 6x10{sup -3}-40 mGy/s together with a good radiation hardness, suggesting possible application in low-dose monitoring.

  5. Radiation effects on carbon fiber reinforced thermoplastics

    SciTech Connect

    Sasuga, Tsuneo; Udagawa, Akira; Seguchi, Tadao

    1993-12-31

    Polyether-ether-ketone (PEEK) and a newly developed thermoplastic polyimide ``new-TPI`` were applied to carbon fiber reinforced plastic (CFRP) as a matrix resin. PEEK and new-TPI showed excellent resistance over 50 MGy to electron irradiation and the crosslinking proceeded predominantly by irradiation. The changes in mechanical properties induced by electron irradiation of the CFRP with the two resins were examined at various temperatures. The flexural strength and modulus measured at {minus}196 and 25{degree}C were scarcely affected up to 120 MGy and both the values measured at high temperature were increased with dose.

  6. The Thermoluminescence Response of Ge-Doped Flat Fibers to Gamma Radiation.

    PubMed

    Nawi, Siti Nurasiah Binti Mat; Wahib, Nor Fadira Binti; Zulkepely, Nurul Najua Binti; Amin, Yusoff Bin Mohd; Min, Ung Ngie; Bradley, David Andrew; Nor, Roslan Bin Md; Maah, Mohd Jamil

    2015-01-01

    Study has been undertaken of the thermoluminescence (TL) yield of various tailor-made flat cross-section 6 mol% Ge-doped silica fibers, differing only in respect of external dimensions. Key TL dosimetric characteristics have been investigated, including glow curves, dose response, sensitivity, fading and reproducibility. Using a (60)Co source, the samples were irradiated to doses within the range 1 to 10 Gy. Prior to irradiation, the flat fibers were sectioned into 6 mm lengths, weighed, and annealed at 400 °C for 1 h. TL readout was by means of a Harshaw Model 3500 TLD reader, with TLD-100 chips (LiF:Mg, Ti) used as a reference dosimeter to allow the relative response of the fibers to be evaluated. The fibers have been found to provide highly linear dose response and excellent reproducibility over the range of doses investigated, demonstrating high potential as TL-mode detectors in radiation medicine applications. Mass for mass, the results show the greatest TL yield to be provided by fibers of the smallest cross-section, analysis indicating this to be due to minimal light loss in transport of the TL through the bulk of the silica medium. PMID:26307987

  7. The Thermoluminescence Response of Ge-Doped Flat Fibers to Gamma Radiation

    PubMed Central

    Mat Nawi, Siti Nurasiah Binti; Wahib, Nor Fadira Binti; Zulkepely, Nurul Najua Binti; Amin, Yusoff Bin Mohd; Min, Ung Ngie; Bradley, David Andrew; Md Nor, Roslan Bin; Maah, Mohd Jamil

    2015-01-01

    Study has been undertaken of the thermoluminescence (TL) yield of various tailor-made flat cross-section 6 mol% Ge-doped silica fibers, differing only in respect of external dimensions. Key TL dosimetric characteristics have been investigated, including glow curves, dose response, sensitivity, fading and reproducibility. Using a 60Co source, the samples were irradiated to doses within the range 1 to 10 Gy. Prior to irradiation, the flat fibers were sectioned into 6 mm lengths, weighed, and annealed at 400 °C for 1 h. TL readout was by means of a Harshaw Model 3500 TLD reader, with TLD-100 chips (LiF:Mg, Ti) used as a reference dosimeter to allow the relative response of the fibers to be evaluated. The fibers have been found to provide highly linear dose response and excellent reproducibility over the range of doses investigated, demonstrating high potential as TL-mode detectors in radiation medicine applications. Mass for mass, the results show the greatest TL yield to be provided by fibers of the smallest cross-section, analysis indicating this to be due to minimal light loss in transport of the TL through the bulk of the silica medium. PMID:26307987

  8. The Thermoluminescence Response of Ge-Doped Flat Fibers to Gamma Radiation.

    PubMed

    Nawi, Siti Nurasiah Binti Mat; Wahib, Nor Fadira Binti; Zulkepely, Nurul Najua Binti; Amin, Yusoff Bin Mohd; Min, Ung Ngie; Bradley, David Andrew; Nor, Roslan Bin Md; Maah, Mohd Jamil

    2015-08-20

    Study has been undertaken of the thermoluminescence (TL) yield of various tailor-made flat cross-section 6 mol% Ge-doped silica fibers, differing only in respect of external dimensions. Key TL dosimetric characteristics have been investigated, including glow curves, dose response, sensitivity, fading and reproducibility. Using a (60)Co source, the samples were irradiated to doses within the range 1 to 10 Gy. Prior to irradiation, the flat fibers were sectioned into 6 mm lengths, weighed, and annealed at 400 °C for 1 h. TL readout was by means of a Harshaw Model 3500 TLD reader, with TLD-100 chips (LiF:Mg, Ti) used as a reference dosimeter to allow the relative response of the fibers to be evaluated. The fibers have been found to provide highly linear dose response and excellent reproducibility over the range of doses investigated, demonstrating high potential as TL-mode detectors in radiation medicine applications. Mass for mass, the results show the greatest TL yield to be provided by fibers of the smallest cross-section, analysis indicating this to be due to minimal light loss in transport of the TL through the bulk of the silica medium.

  9. A Multi-Anode Photomultiplier Tube Based Wavelength-Shifting-Fiber Detector for neutron diffraction

    SciTech Connect

    Berry, Kevin D; Clonts, Lloyd G; Crow, Lowell; Diawara, Yacouba; Funk, Loren L; Hannan, Bruce W; Hodges, Jason P; Riedel, Richard A; Wang, Cai-Lin

    2012-01-01

    The wavelength-shifting (WLS) fiber scintillator neutron detectors were developed for two time-of-flight (TOF) neutron powder diffractometers (POWGEN, VULCAN) at Spallation Neutron Source (SNS). In a recent module (v3.0), however, there are 32 1-inch-diameter photomultiplier tubes (PMTs) which are bulky and expensive. We built a new detector module (v3.1) based on four multi-anode (MA) PMTs, and tested its performance including detection efficiency, count rate capability, spatial resolution, ghosting properties, and gamma-ray sensitivity. The v3.1 module was compared with two prior v3.0 modules, and 3He tube detectors.

  10. 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

  11. A Scintillator tile-fiber preshower detector for the CDF Central Calorimeter

    SciTech Connect

    S. Lami

    2004-08-12

    The front face of the CDF central calorimeter is being equipped with a new Preshower detector, based on scintillator tiles read out by WLS fibers. A light yield of about 40 pe/MIP at the tile exit was obtained, exceeding the design requirements.

  12. Development of a thermal neutron detector based on scintillating fibers and silicon photomultipliers

    SciTech Connect

    Barbagallo, Massimo; Greco, Giuseppe; Scire, Carlotta; Scire, Sergio; Cosentino, Luigi; Pappalardo, Alfio; Finocchiaro, Paolo; Montereali, Rosa Maria; Vincenti, Maria Aurora

    2010-09-15

    We propose a technique for thermal neutron detection, based on a {sup 6}Li converter placed in front of scintillating fibers readout by means of silicon photomultipliers. Such a technique allows building cheap and compact detectors and dosimeters, thus possibly opening new perspectives in terms of granular monitoring of neutron fluxes as well as space-resolved neutron detection.

  13. Elimination of ghosting artifacts from wavelength-shifting fiber neutron detectors

    SciTech Connect

    Wang, C. L.; Diawara, Y.; Hannan, B. W.; Hodges, J. P.; Clonts, L. G.

    2013-01-15

    Misassignment of neutron position (ghosting) produces artifacts which have been observed in wavelength-shifting (WLS) fiber detectors developed for time-of-flight (TOF) neutron powder diffraction. In position-sensitive detectors (PSDs) with WLS fiber encoding, thermal and cold neutrons interact with a monolithic {sup 6}LiF/ZnS:Ag scintillator screen, and scintillation photons are generated and transported through the crossed fibers to photomultipliers (PMTs). The neutron position is determined by photon counts in the PMTs within a preset time window. Ghosting occurs when neutrons hit the group boundaries of two neighboring PMTs for x-position multiplexing, which is modeled as resulting from a long travel length (about 3-5 mm) of a small number of scintillation photons. This model is supported by the change observed in aperture images when the threshold number for photon-pulses was adjusted for neutron event determination. When the threshold number of photon-pulses was set above 10 for each PMT, the ghost peaks in the aperture images and TOF spectra of powder diffraction were strongly suppressed or completely eliminated, and the intrinsic background levels of the WLS detectors were significantly reduced. Our result indicates that WLS fiber detector is a promising alternative for {sup 3}He PSDs for neutron scattering.

  14. Elimination of ghosting artifacts from wavelength-shifting fiber neutron detectors

    SciTech Connect

    Clonts, Lloyd G.; Diawara, Yacouba; Hannan, Bruce W.; Hodges, Jason P.; Wang, Cai-Lin

    2013-01-31

    Misassignment of neutron position (ghosting) produces artifacts, which have been observed in wavelength-shifting (WLS) fiber detectors developed for time-of-flight (TOF) neutron powder diffraction. In position-sensitive detectors (PSDs) with WLS fiber encoding, thermal and cold neutrons interact with a monolithic 6LiF/ZnS:Ag scintillator screen, and scintillation photons are generated and transported through the crossed fibers to photomultipliers (PMTs). The neutron position is determined by photon counts in PMTs within a preset time window. Ghosting occurs when neutrons hit the group boundaries of two neighboring PMTs for x-position multiplexing, which is modeled as resulting from a long travel length (about 3-5 mm) of a small number of scintillation photons. This model is supported by the change observed in aperture images when the threshold number for photon-pulses was adjusted for a neutron event determination. When the threshold number of photon-pulses was set above 10 for each PMT, the ghost peaks in the aperture images and TOF spectra of powder diffraction were strongly suppressed or completely eliminated, and the intrinsic background levels of the WLS detectors were significantly reduced. Our result indicates that WLS fiber detector is a promising alternative for 3He PSDs for neutron scattering.

  15. Examination of cotton fibers and common contaminants using an infrared microscope and a focal-plane array detector

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The chemical imaging of cotton fibers and common contaminants in fibers is presented. Chemical imaging was performed with an infrared microscope equipped with a Focal-Plane Array (FPA) detector. Infrared spectroscopy can provide us with information on the structure and quality of cotton fibers. In a...

  16. 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.

  17. The point-spread function of fiber-coupled area detectors

    PubMed Central

    Holton, James M.; Nielsen, Chris; Frankel, Kenneth A.

    2012-01-01

    The point-spread function (PSF) of a fiber-optic taper-coupled CCD area detector was measured over five decades of intensity using a 20 µm X-ray beam and ∼2000-fold averaging. The ‘tails’ of the PSF clearly revealed that it is neither Gaussian nor Lorentzian, but instead resembles the solid angle subtended by a pixel at a point source of light held a small distance (∼27 µm) above the pixel plane. This converges to an inverse cube law far from the beam impact point. Further analysis revealed that the tails are dominated by the fiber-optic taper, with negligible contribution from the phosphor, suggesting that the PSF of all fiber-coupled CCD-type detectors is best described as a Moffat function. PMID:23093762

  18. Influence of structure on radiation shielding effectiveness of graphite fiber reinforced polyethylene composite

    NASA Astrophysics Data System (ADS)

    Emmanuel, A.; Raghavan, J.

    2015-10-01

    While LEO and GEO are used for most satellite missions, Highly Elliptical Orbits (HEOs) are also used for satellite missions covering Polar Regions of Earth. Satellites in HEO are exposed to a relatively harsher radiation environment than LEO and GEO. The mass of traditionally used aluminum radiation shield, required to attenuate the radiation to a level below a certain threshold that is safe for the satellite bus and payload, scales with the level of radiation. It has been shown (Emmanuel et al., 2014) that materials with low atomic number (Z) such as polyethylene (PE) can result in a lighter shield than aluminum (Al) in HEO. However, PE has to be reinforced with relatively high Z fibers such as graphite (G) to improve its mechanical properties. The effect of introduction of G and the resulting composite structure (that meets the requirements on mechanical properties, manufacturing and service) on the radiation shielding effectiveness of PE was studied through simulation using a layered PE-G composite. The Total Ionization Dose (TID), deposited in a silicon detector behind the composite shield, has been found to be function of layer volume fraction, layer thickness and stacking sequence of the PE and G layers. One composite configuration has resulted in a TID lower than that for PE, demonstrating the possibility of tailoring the mechanical properties of PE-based composite radiation shield with minimal negative impact on its radiation shielding effectiveness.

  19. 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. (Inventor)

    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.

  20. Measurement of the radiation field surrounding the Collider Detector at Fermilab

    SciTech Connect

    K. Kordas et al.

    2004-01-28

    We present here the first direct and detailed measurements of the spatial distribution of the ionizing radiation surrounding a hadron collider experiment. Using data from two different exposures we measure the effect of additional shielding on the radiation field around the Collider Detector at Fermilab (CDF). Employing a simple model we parameterize the ionizing radiation field surrounding the detector.

  1. 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.

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

    DOEpatents

    McQuaid, James H.; Lavietes, Anthony D.

    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.

  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. 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 μm 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 μm / 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 μm 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.

  5. Initial performance of the VENUS transition radiation detector

    NASA Astrophysics Data System (ADS)

    Terunuma, N.; Kanda, N.; Sakuda, M.; Chiba, Y.; Fukushima, Y.; Haba, J.; Krüger, A.; Nakano, I.; Nakamura, S.; Ogawa, K.; Ohsugi, T.; Suzuki, A.; Watase, Y.

    1992-12-01

    The VENUS-TRD is a cylindrical transition radiation detector, extending from 127 cm to 157.7 cm radially and 296 cm axially. It is designed to improve the e/π separation capability of the VENUS detector by a factor of 10 in order to complement the lead glass calorimeter. It covers an angular region of cos θ < 0.68 and contains four layers of radiators and X-ray chambers. It has been working very stably since it started data-taking at the TRISTAN e+e- storage ring in June, 1991. The pion rejection power (Rπ = 1/ɛπ) at an electron efficiency of 90% is Rπ = 10+/-1 and 15+/-2 for isolated tracks with a momentum range of 1 < P < 3 and 3 < P < 10 GeV/c, respectively. It decreases to Rπ = 7+/-1 for tracks with P > 1 GeV/c in hadronic events due to overlap of the tracks in the chamber cells of the TRD. The VENUS-TRD is the largest TRD to perform in colliding beam experiments.

  6. Room temperature aluminum antimonide radiation detector and methods thereof

    DOEpatents

    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).

  7. 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.

  8. 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.

  9. 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 γ>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

  10. Radiation-curable carbon fiber prepreg composites

    SciTech Connect

    Saunders, C.B.; Dickson, L.W.; Singh, A.; Carmichael, A.A.; Lopata, V.J.

    1988-12-01

    A radiation-curable prepreg designed to meet the specifications set by a major aircraft company is described. The resin, consisting of a mixture of an epoxy diacrylate, polybutadiene diacrylate, and a multifunctional monomer, was used to impregnate a plain weave carbon fabric by a solvent process. The cured polymer, produced by irradiation in air to a dose of 40 kGy, is amorphous, with a gel fraction of 85 percent. The linear thermal expansion coefficient of the polymer was found to be 0.00017 m/m deg C from 25 to 150 C; it was not affected by varying the applied irradiation dose from 30 to 50 kGy. 14 references.

  11. Characterization of a scintillating fibers read by MPPC detectors trigger prototype for the AMADEUS experiment

    NASA Astrophysics Data System (ADS)

    Bazzi, M.; Berucci, C.; Curceanu, C.; D'Uffizi, A.; Piscicchia, K.; Poli Lener, M.; Romero Vidal, A.; Sbardella, E.; Scordo, A.; Vazquez Doce, O.

    2013-05-01

    Multi-Pixel Photon Counters (MPPC) consist of hundreds of micro silicon Avalanche PhotoDiodes (APD) working in Geiger mode. The high gain and the low noise, typical of these devices, together with their good performance in magnetic field, make them ideal readout detectors for scintillating fibers as trigger detectors in particle and nuclear physics experiments like AMADEUS, where such detectors are planned to be used to trigger on charged kaon pairs. In order to investigate the detection efficiency of such a system, a prototype setup consisting of 32, 1 mm diameter scintillating fibers, arranged in two double layers of 16 fibers each, and read out at both sides by 64 MPPCs with an ad-hoc built readout electronics, was tested at the πM-1 line of the Paul Scherrer Institute (PSI) in Villigen, Switzerland. The detection efficiency and the trigger capability were measured on a beam containing protons, electrons, muons and pions with a momentum of 440 MeV/c. The measured average efficiency for protons for a double layer of scintillating fibers (96.2±1.0%) represents a guarantee of the good performance of this system as a trigger for the AMADEUS experiment.

  12. Recovery of optical properties using interstitial cylindrical diffusers as source and detector fibers

    NASA Astrophysics Data System (ADS)

    Baran, Timothy M.

    2016-07-01

    We demonstrate recovery of optical properties using arrays of interstitial cylindrical diffusing fibers as sources and detectors. A single 1-cm diffuser delivered laser illumination at 665 nm, while seven 1- and 2-cm diffusers at 1-cm grid spacing acted as detectors. Extraction of optical properties from these measurements was based upon a diffusion model of emission and detection distributions for these diffuser fibers, informed by previous measurements of heterogeneous axial detection. Verification of the technique was performed in 15 liquid tissue-simulating phantoms consisting of deionized water, India ink as absorber, and Intralipid 20% as scatterer. For the range of optical properties tested, mean errors were 4.4% for effective attenuation coefficient, 12.6% for absorption coefficient, and 7.6% for reduced scattering coefficient. Error in recovery tended to increase with decreasing transport albedo. For therapeutic techniques involving the delivery of light to locations deep within the body, such as interstitial photodynamic and photothermal therapies, the methods described here would allow the treatment diffuser fibers also to be used as sources and detectors for recovery of optical properties. This would eliminate the need for separately inserted fibers for spectroscopy, reducing clinical complexity and improving the accuracy of treatment planning.

  13. Effect of microwave radiation on Jayadhar cotton fibers: WAXS studies

    SciTech Connect

    Niranjana, A. R. Mahesh, S. S. Divakara, S. Somashekar, R.

    2014-04-24

    Thermal effect in the form of micro wave energy on Jayadhar cotton fiber has been investigated. Microstructural parameters have been estimated using wide angle x-ray scattering (WAXS) data and line profile analysis program developed by us. Physical properties like tensile strength are correlated with X-ray results. We observe that the microwave radiation do affect significantly many parameters and we have suggested a multivariate analysis of these parameters to arrive at a significant result.

  14. 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.

  15. Activation of Organic Photovoltaic Light Detectors Using Bend Leakage from Optical Fibers.

    PubMed

    Griffith, Matthew J; Willis, Matthew S; Kumar, Pankaj; Holdsworth, John L; Bezuidenhout, Henco; Zhou, Xiaojing; Belcher, Warwick; Dastoor, Paul C

    2016-03-01

    This work investigates the detection and subsequent utilization of leaked light from bends in a silica optical fiber using organic photovoltaic detectors. The optic power lost by single mode and multimode silica optical fibers was calibrated for bend radii between 1 and 7 mm for 532 and 633 nm light, exhibiting excellent agreement with previous theoretical solutions. The spatial location of maximum power leakage on the exterior of the fiber was found to exist in the same plane as the fiber, with a 10° offset from the normal. Two different organic photovoltaic detectors fabricated using a poly(3-hexylthiophene):indene-C60-bisadduct donor-acceptor blend cast from chloroform and chlorobenzene were fabricated to detect the leaked light. The two detectors exhibited different photovoltaic performances, predominantly due to different active layer thicknesses. Both devices showed sensitivity to leakage light, exhibiting voltages between 200 and 300 mV in response to leaked light from the fiber. The temporal responses of the devices were observed to differ, with a rise time from 10% to 90% of maximum voltage of 1430 μs for the chlorobenzene device, and a corresponding rise time of 490 μs for the higher performing chloroform device. The two OPVs were used to simultaneously detect leaked light from induced bends in the optical fiber, with the differing temporal profiles employed to create a unique time-correlated detection signal with enhanced security. The delay between detection of each OPV voltage could be systematically varied, allowing for either a programmable and secure single detection signal or triggering of multiple events with variable time resolution. The results reported in this study present exciting avenues toward the deployment of this simple and noninvasive optical detection system in a range of different applications. PMID:26891938

  16. Activation of Organic Photovoltaic Light Detectors Using Bend Leakage from Optical Fibers.

    PubMed

    Griffith, Matthew J; Willis, Matthew S; Kumar, Pankaj; Holdsworth, John L; Bezuidenhout, Henco; Zhou, Xiaojing; Belcher, Warwick; Dastoor, Paul C

    2016-03-01

    This work investigates the detection and subsequent utilization of leaked light from bends in a silica optical fiber using organic photovoltaic detectors. The optic power lost by single mode and multimode silica optical fibers was calibrated for bend radii between 1 and 7 mm for 532 and 633 nm light, exhibiting excellent agreement with previous theoretical solutions. The spatial location of maximum power leakage on the exterior of the fiber was found to exist in the same plane as the fiber, with a 10° offset from the normal. Two different organic photovoltaic detectors fabricated using a poly(3-hexylthiophene):indene-C60-bisadduct donor-acceptor blend cast from chloroform and chlorobenzene were fabricated to detect the leaked light. The two detectors exhibited different photovoltaic performances, predominantly due to different active layer thicknesses. Both devices showed sensitivity to leakage light, exhibiting voltages between 200 and 300 mV in response to leaked light from the fiber. The temporal responses of the devices were observed to differ, with a rise time from 10% to 90% of maximum voltage of 1430 μs for the chlorobenzene device, and a corresponding rise time of 490 μs for the higher performing chloroform device. The two OPVs were used to simultaneously detect leaked light from induced bends in the optical fiber, with the differing temporal profiles employed to create a unique time-correlated detection signal with enhanced security. The delay between detection of each OPV voltage could be systematically varied, allowing for either a programmable and secure single detection signal or triggering of multiple events with variable time resolution. The results reported in this study present exciting avenues toward the deployment of this simple and noninvasive optical detection system in a range of different applications.

  17. Characterizing energy dependence and count rate performance of a dual scintillator fiber-optic detector for computed tomography

    SciTech Connect

    Hoerner, Matthew R. Stepusin, Elliott J.; Hyer, Daniel E.; Hintenlang, David E.

    2015-03-15

    Purpose: Kilovoltage (kV) x-rays pose a significant challenge for radiation dosimetry. In the kV energy range, even small differences in material composition can result in significant variations in the absorbed energy between soft tissue and the detector. In addition, the use of electronic systems in light detection has demonstrated measurement losses at high photon fluence rates incident to the detector. This study investigated the feasibility of using a novel dual scintillator detector and whether its response to changes in beam energy from scatter and hardening is readily quantified. The detector incorporates a tissue-equivalent plastic scintillator and a gadolinium oxysulfide scintillator, which has a higher sensitivity to scatter x-rays. Methods: The detector was constructed by coupling two scintillators: (1) small cylindrical plastic scintillator, 500 μm in diameter and 2 mm in length, and (2) 100 micron sheet of gadolinium oxysulfide 500 μm in diameter, each to a 2 m long optical fiber, which acts as a light guide to transmit scintillation photons from the sensitive element to a photomultiplier tube. Count rate linearity data were obtained from a wide range of exposure rates delivered from a radiological x-ray tube by adjusting the tube current. The data were fitted to a nonparalyzable dead time model to characterize the time response. The true counting rate was related to the reference free air dose air rate measured with a 0.6 cm{sup 3} Radcal{sup ®} thimble chamber as described in AAPM Report No. 111. Secondary electron and photon spectra were evaluated using Monte Carlo techniques to analyze ionization quenching and photon energy-absorption characteristics from free-in-air and in phantom measurements. The depth/energy dependence of the detector was characterized using a computed tomography dose index QA phantom consisting of nested adult head and body segments. The phantom provided up to 32 cm of acrylic with a compatible 0.6 cm{sup 3} calibrated

  18. A New scintillator tile / fiber preshower detector for the CDF central calorimeter

    SciTech Connect

    Gallinaro, Michele; Artikov, A.; Bromberg, C.; Budagov, J.; Byrum, K.; Chang, S.; Chlachidze, G.; Goulianos, K.; Huston, J.; Iori, M.; Kim, M.; Kuhlmann, S.; Lami, S.; Lindgren, M.; Lytken, E.; Miller, R.; Nodulman, L.; Pauletta, G.; Penzo, A.; Proudfoot, J.; Roser, R.; /Argonne /Dubna, JINR /Fermilab /Kyungpook Natl. U. /Michigan State U. /INFN, Siena /Rockefeller U. /INFN, Rome /INFN, Trieste /INFN, Udine /Tsukuba U.

    2004-11-01

    A detector designed to measure early particle showers has been installed in front of the central CDF calorimeter at the Tevatron. This new preshower detector is based on scintillator tiles coupled to wavelength-shifting fibers read out by multianode photomultipliers and has a total of 3,072 readout channels. The replacement of the old gas detector was required due to an expected increase in instantaneous luminosity of the Tevatron collider in the next few years. Calorimeter coverage, jet energy resolution, and electron and photon identification are among the expected improvements. The final detector design, together with the R&D studies that led to the choice of scintillator and fiber, mechanical assembly, and quality control are presented. The detector was installed in the fall 2004 Tevatron shutdown and is expected to start collecting colliding beam data by the end of 2004. First measurements indicate a light yield of 12 photoelectrons/MIP, a more than two-fold increase over the design goals.

  19. 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

  20. Field-deployable gamma-radiation detectors for DHS use

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Sanjoy

    2007-09-01

    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 TM, 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 TM that enables emergency personnel to obtain real-time technical analysis of radiation samples they find in the field1. 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

  1. 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

  2. Feasibility of fiber-optic radiation sensor using Cerenkov effect for detecting thermal neutrons.

    PubMed

    Jang, Kyoung Won; Yagi, Takahiro; Pyeon, Cheol Ho; Yoo, Wook Jae; Shin, Sang Hun; Misawa, Tsuyoshi; Lee, Bongsoo

    2013-06-17

    In this research, we propose a novel method for detecting thermal neutrons with a fiber-optic radiation sensor using the Cerenkov effect. We fabricate a fiber-optic radiation sensor that detects thermal neutrons with a Gd-foil, a rutile crystal, and a plastic optical fiber. The relationship between the fluxes of electrons inducing Cerenkov radiation in the sensor probe of the fiber-optic radiation sensor and thermal neutron fluxes is determined using the Monte Carlo N-particle transport code simulations. To evaluate the fiber-optic radiation sensor, the Cerenkov radiation generated in the fiber-optic radiation sensor by irradiation of pure thermal neutron beams is measured according to the depths of polyethylene.

  3. 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.

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

    DOEpatents

    Johnson, Larry O.; McIsaac, Charles V.; Lawrence, Robert S.; Grafwallner, Ervin G.

    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.

  5. 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.

  6. Field profile tailoring in a-Si:H radiation detectors

    SciTech Connect

    Fujieda, I.; Cho, G.; Conti, M.; Drewery, J.; Kaplan, S.N.; Perez-Mendez, V.; Quershi, S.; Wildermuth, D. ); Street, R.A. )

    1990-03-01

    The capability of tailoring the field profile in reverse-biased a-Si:H diodes by doping and/or manipulating electrode shapes opens a way to many interesting device structures. Charge collection in a-Si:H radiation detectors is improved for high LET particle detection by inserting thin doped layers into the i-layer of the usual p-i-n diode. This buried p-i-n structure enables us to apply higher reverse-bias and the electric field is enhanced in the mid i-layer. Field profiles of the new structures are calculated and the improved charge collection process is discussed. Also discussed is the possibility of field profile tailoring by utilizing the fixed space charges in i-layers and/or manipulating electrode shapes of the reverse-biased p-i-n diodes. 10 refs., 7 figs.

  7. 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.

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

    DOEpatents

    Majewski, Stanislaw; Kross, Brian J.; Zorn, Carl J.; Majewski, Lukasz A.

    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.

  9. 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.

  10. Compensation for radiation damage of SOI pixel detector via tunneling

    NASA Astrophysics Data System (ADS)

    Yamada, M.; Arai, Y.; Fujita, Y.; Hamasaki, R.; Ikegami, Y.; Kurachi, I.; Miyoshi, T.; Nishimura, R.; Tauchi, K.; Tsuboyama, T.

    2016-09-01

    We are developing a method for removing holes trapped in the oxide layer of a silicon-on-insulator (SOI) monolithic pixel detector after irradiation. Radiation that passes through the detector generates positive charge by trapped holes in the buried oxide layer (BOX) underneath the MOSFET. The positive potential caused by these trapped holes modifies the characteristics of the MOSFET of the signal readout circuit. In order to compensate for the effect of the positive potential, we tried to recombine the trapped holes with electrons via Fowler-Nordheim (FN) tunneling. By applying high voltage to the buried p-well (BPW) under the oxide layer with the MOSFET fixed at 0 V, electrons are injected into the BOX by FN tunneling. X-rays cause a negative shift in the threshold voltage Vth of the MOSFET. We can successfully recover Vth close to its pre-irradiation level after applying VBPW ≥ 120 V. However, the drain leakage current increased after applying VBPW; we find that this can be suppressed by applying a negative voltage to the BPW.

  11. 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.

  12. Gas mixtures for gas-filled radiation detectors

    DOEpatents

    Christophorou, Loucas G.; McCorkle, Dennis L.; Maxey, David V.; Carter, James G.

    1982-01-05

    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.

  13. RADIATION EFFECTS ON EPOXY/CARBON-FIBER COMPOSITE

    SciTech Connect

    Hoffman, E

    2008-01-11

    Piping in the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS) must withstand the stresses involved during an unlikely but potential deflagration event. One method proposed for protection and reinforcement of piping during such an event is the use of a carbon fiber-reinforced epoxy composite (Diamond-Wrap{reg_sign}). In the DWPF, this reinforcement composite product would be required to maintain its safety function for a 20-year service life. This product has been ASME-approved (nuclear code case 589) for post-construction maintenance and is DOT-compliant per 49CFR 192 and 195. However, its radiation resistance properties have not been evaluated. This report documents initial radiation resistance testing of the product and microstructural effects. Additional testing is recommended to evaluate radiation effects on specific properties such as burst strength, chemical resistance/weeping and for service life prediction in critical applications.

  14. Comparative Response of Microchannel Plate and Channel Electron Multiplier Detectors to Penetrating Radiation in Space

    SciTech Connect

    Funsten, Herbert O.; Harper, Ronnie W.; Dors, Eric E.; Janzen, Paul A.; Larsen, Brian A.; MacDonald, Elizabeth A.; Poston, David I.; Ritzau, Stephen M.; Skoug, Ruth M.; Zurbuchen, Thomas H.

    2015-10-02

    Channel electron multiplier (CEM) and microchannel plate (MCP) detectors are routinely used in space instrumentation for measurement of space plasmas. Here, our goal is to understand the relative sensitivities of these detectors to penetrating radiation in space, which can generate background counts and shorten detector lifetime. We use 662 keV γ-rays as a proxy for penetrating radiation such as γ-rays, cosmic rays, and high-energy electrons and protons that are ubiquitous in the space environment. We find that MCP detectors are ~20 times more sensitive to 662 keV γ-rays than CEM detectors. This is attributed to the larger total area of multiplication channels in an MCP detector that is sensitive to electronic excitation and ionization resulting from the interaction of penetrating radiation with the detector material. In contrast to the CEM detector, whose quantum efficiency εγ for 662 keVγ -rays is found to be 0.00175 and largely independent of detector bias, the quantum efficiency of the MCP detector is strongly dependent on the detector bias, with a power law index of 5.5. Lastly, background counts in MCP detectors from penetrating radiation can be reduced using MCP geometries with higher pitch and smaller channel diameter.

  15. Comparative Response of Microchannel Plate and Channel Electron Multiplier Detectors to Penetrating Radiation in Space

    DOE PAGESBeta

    Funsten, Herbert O.; Harper, Ronnie W.; Dors, Eric E.; Janzen, Paul A.; Larsen, Brian A.; MacDonald, Elizabeth A.; Poston, David I.; Ritzau, Stephen M.; Skoug, Ruth M.; Zurbuchen, Thomas H.

    2015-10-02

    Channel electron multiplier (CEM) and microchannel plate (MCP) detectors are routinely used in space instrumentation for measurement of space plasmas. Here, our goal is to understand the relative sensitivities of these detectors to penetrating radiation in space, which can generate background counts and shorten detector lifetime. We use 662 keV γ-rays as a proxy for penetrating radiation such as γ-rays, cosmic rays, and high-energy electrons and protons that are ubiquitous in the space environment. We find that MCP detectors are ~20 times more sensitive to 662 keV γ-rays than CEM detectors. This is attributed to the larger total area ofmore » multiplication channels in an MCP detector that is sensitive to electronic excitation and ionization resulting from the interaction of penetrating radiation with the detector material. In contrast to the CEM detector, whose quantum efficiency εγ for 662 keVγ -rays is found to be 0.00175 and largely independent of detector bias, the quantum efficiency of the MCP detector is strongly dependent on the detector bias, with a power law index of 5.5. Lastly, background counts in MCP detectors from penetrating radiation can be reduced using MCP geometries with higher pitch and smaller channel diameter.« less

  16. Radiation response of SiC-based fibers

    SciTech Connect

    Youngblood, G.E.; Jones, R.H.; Kohyama, Akira; Snead, L.L.

    1998-03-01

    The radiation response of a base-line carbide composite (SiC/SiC) made with Nicalon{trademark} CG fiber reinforcement was presented for a broad range of dose and irradiation temperatures. Strength loss in this composite and a similar composite made with Tyranno{trademark} fiber was related to shrinkage and a predicted mass loss in the Nicalon CG or Tyranno fibers. In Table 1, measured relative density and length changes ({Delta}p/p{sub o} and {Delta}L/L{sub o}, respectively) for coated and uncoated fibers irradiated at high doses and temperatures (43 dpa-SiC at 1000 C and 80 dpa-SiC at 800 C) are given. Also given are the relative mass loss changes {Delta}m/m{sub o}, calculated from {Delta}p/p{sub o} and {Delta}L/L{sub o} by the expression {Delta}m/m{sub o} = 3 {Delta}L/L{sub o} + {Delta}p/p{sub o}.

  17. Radiation detector device for rejecting and excluding incomplete charge collection events

    DOEpatents

    Bolotnikov, Aleksey E.; De Geronimo, Gianluigi; Vernon, Emerson; Yang, Ge; Camarda, Giuseppe; Cui, Yonggang; Hossain, Anwar; Kim, Ki Hyun; James, Ralph B.

    2016-05-10

    A radiation detector device is provided that is capable of distinguishing between full charge collection (FCC) events and incomplete charge collection (ICC) events based upon a correlation value comparison algorithm that compares correlation values calculated for individually sensed radiation detection events with a calibrated FCC event correlation function. The calibrated FCC event correlation function serves as a reference curve utilized by a correlation value comparison algorithm to determine whether a sensed radiation detection event fits the profile of the FCC event correlation function within the noise tolerances of the radiation detector device. If the radiation detection event is determined to be an ICC event, then the spectrum for the ICC event is rejected and excluded from inclusion in the radiation detector device spectral analyses. The radiation detector device also can calculate a performance factor to determine the efficacy of distinguishing between FCC and ICC events.

  18. All-fiber photoacoustic gas sensor with graphene nano-mechanical resonator as the acoustic detector

    NASA Astrophysics Data System (ADS)

    Yanzhen, Tan; Fan, Yang; Jun, Ma; Hoi Lut, Ho; Wei, Jin

    2015-09-01

    We demonstrate an all-optical-fiber photoacoustic (PA) spectrometric gas sensor with a graphene nano-mechanical resonator as the acoustic detector. The acoustic detection is performed by a miniature ferrule-top nano-mechanical resonator with a ˜100-nm-thick, 2.5-mm-diameter multilayer graphene diaphragm. Experimental investigation showed that the performance of the PA gas sensor can be significantly enhanced by operating at the resonance of the grapheme diaphragm where a lower detection limit of 153 parts-per-billion (ppb) acetylene is achieved. The all-fiber PA sensor which is immune to electromagnetic interference and safe in explosive environments is ideally suited for real-world remote, space-limited applications and for multipoint detection in a multiplexed fiber optic sensor network.

  19. A tunable fiber-coupled optical cavity for agile enhancement of detector absorption

    NASA Astrophysics Data System (ADS)

    Heath, Robert M.; Tanner, Michael G.; Kirkwood, Robert A.; Miki, Shigehito; Warburton, Richard J.; Hadfield, Robert H.

    2016-09-01

    Maximizing photon absorption into thin active structures can be the limiting factor for photodetector efficiency. In this work, a fiber-coupled tunable cavity is demonstrated, designed to achieve close to unity absorption of photons into a thin film superconducting nanowire single photon detector (SNSPD). A technique for defining a stable cavity between the end of a telecommunications optical fiber and a reflective substrate is described and realized. Cavity resonances are demonstrated both through the tuning of input wavelength and cavity length. The resulting optical cavity can tune the resonant absorption in situ over a wavelength range of 100 nm. This technique is used to maximize the single photon absorption into both a back-side-coupled Au mirror SNSPD and a front-side-coupled distributed Bragg reflector cavity SNSPD. The system detection efficiency (SDE) is limited by imperfections in the thin films, but in both cases we demonstrate an improvement of the SDE by 40% over bare fiber illumination.

  20. 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.

  1. Radiation Transport Properties of Polyethylene-Fiber Composites

    NASA Technical Reports Server (NTRS)

    Kaul, Raj K.; Barghouty, A. F.; Dahche, H. M.

    2003-01-01

    Composite materials that can both serve as effective shielding materials against cosmic-ray and energetic solar particles in deep space as well as structural materials for habitat and spacecraft remain a critical and mission enabling piece in mission planning and exploration. Polyethylene is known to have excellent shielding properties due to its low density coupled with high hydrogen content. Polyethylene fiber reinforced composites promise to combine this shielding effectiveness with the required mechanical properties of structural materials. Samples of Polyethylene-fiber reinforced epoxy matrix composite 1-5 cm thick were prepared at NASA's Marshall Space Flight Center and tested against 500 MeV/nucleon Fe beam at the HIMAC facility of NIRS in Chiba, Japan. This paper presents measured and calculated results for the radiation transport properties of these samples.

  2. Wavelength-Shifting-Fiber Scintillation Detectors for Thermal Neutron Imaging at SNS

    SciTech Connect

    Clonts, Lloyd G; Cooper, Ronald G; Crow, Lowell; Diawara, Yacouba; Ellis, E Darren; Funk, Loren L; Hannan, Bruce W; Hodges, Jason P; Richards, John D; Riedel, Richard A; Wang, Cai-Lin

    2012-01-01

    We have developed wavelength-Shifting-fiber Scintillator Detector (SSD) with 0.3 m2 area per module. Each module has 154 x 7 pixels and a 5 mm x 50 mm pixel size. Our goal is to design a large area neutron detector offering higher detection efficiency and higher count-rate capability for Time-Of-Flight (TOF) neutron diffraction in Spallation Neutron Source (SNS). A ZnS/6LiF scintillator combined with a novel fiber encoding scheme was used to record the neutron events. A channel read-out-card (CROC) based digital-signal processing electronics and position-determination algorithm was applied for neutron imaging. Neutron-gamma discrimination was carried out using pulse-shape discrimination (PSD). A sandwich flat-scintillator detector can have detection efficiency close to He-3 tubes (about 10 atm). A single layer flat-scintillator detector has count rate capability of 6,500 cps/cm2, which is acceptable for powder diffractometers at SNS.

  3. Performance improvements of wavelength-shifting-fiber neutron detectors using high-resolution positioning algorithms

    DOE PAGESBeta

    Wang, C. L.

    2016-05-17

    On the basis of FluoroBancroft linear-algebraic method [S.B. Andersson, Opt. Exp. 16, 18714 (2008)] three highly-resolved positioning methodswere proposed for wavelength-shifting fiber (WLSF) neutron detectors. Using a Gaussian or exponential-decay light-response function (LRF), the non-linear relation of photon-number profiles vs. x-pixels was linearized and neutron positions were determined. The proposed algorithms give an average 0.03-0.08 pixel position error, much smaller than that (0.29 pixel) from a traditional maximum photon algorithm (MPA). The new algorithms result in better detector uniformity, less position misassignment (ghosting), better spatial resolution, and an equivalent or better instrument resolution in powder diffraction than the MPA. Moreover,more » these characters will facilitate broader applications of WLSF detectors at time-of-flight neutron powder diffraction beamlines, including single-crystal diffraction and texture analysis.« less

  4. 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 α radiation. By measuring the charge collection efficiency (CCE) for variations in bias voltage, CCE values up to 100% have been measured.

  5. 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.

  6. Gamma radiation resistant Fabry-Perot fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Liu, Hanying; Miller, Don W.; Talnagi, Joseph

    2002-08-01

    The Nuclear Regulatory Commission (NRC) in 1998 completed a study of emerging technologies that could be applicable to measurement systems in nuclear power plants [H. M. Hashemian [et al.], "Advanced Instrumentation and Maintenance Technologies for Nuclear Power Plants," NUREG/CR-5501 (1998)]. This study concluded that advanced fiber optic sensing technology is an emerging technology that should be investigated. It also indicated that there had been very little research related to performance evaluation of fiber optic sensors in nuclear plant harsh environments, although substantial research has been performed on nuclear radiation effects on optical fibers in the last two decades. A type of Fabry-Perot fiber optic temperature sensor, which is manufactured by Fiso Technologies in Canada, is qualified to be a candidate for potential applications in nuclear radiation environment due to its unique signal processing technique and its resistance to power loss. The gamma irradiation effects on this type of sensors are investigated in this article. Two sensors were irradiated in a gamma irradiation field and one of them was irradiated up to a total gamma dose of 133 Mrad. The sensor on-line performance was monitored during each gamma irradiation test. Furthermore, the sensor static and dynamic performance before and after each irradiation test were evaluated according to the Standard ISA-dS67.06.01 ("Performance Monitoring for Nuclear Safety-Related Instrument Channels in Nuclear Power Plants", Standard ISA-dS67.06.01, Draft 7, Instrument Society of America, 1999). Although several abnormal phenomena were observed, analysis shows that gamma irradiation is not accredited to the abnormal behavior, which implies that this type of sensor is suitable to a gamma irradiation environment with a high gamma dose.

  7. Radiation heat transfer within an optical fiber draw tower furnace

    SciTech Connect

    Issa, J.; Jaluria, Y.; Polymeropoulos, C.E.; Yin, Z.

    1995-12-31

    Study of the thermal transport and material flow processes associated with the drawing of optical fiber in a graphite draw furnace requires modeling of the heat transfer from the furnace wall. Previous work has shown that accurate knowledge of the furnace heater element axial temperature distribution is essential for proper modeling of the radiative transfer process. The present work is aimed at providing this information, as well as generating a set of data for the study of radiation exchange in the furnace cavity. The experimental procedure involved measuring the centerline temperature distribution in graphite and fused silica rods inserted into an optical fiber draw tower furnace. The temperature measurements were then used along with a model for radiative-convective heat transfer in the furnace in order to obtain the furnace temperature profile. This is an inverse problem since the centerline temperature in the rod is known whereas the furnace thermal conditions are not. The results obtained showed that the furnace temperature distribution was independent of rod material and size. The shape of the computed temperature distributions suggest that they can be well represented by a Gaussian function.

  8. Effect of a metal electrode on the radiation tolerance of a SiC neutron detector

    NASA Astrophysics Data System (ADS)

    Park, Junesic; Shin, Hee-Sung; Kim, Ho-Dong; Kim, Han Soo; Park, Se Hwan; Lee, Cheol Ho; Kim, Yong Kyun

    2012-08-01

    The Korea Atomic Energy Research Institute (KAERI) has developed a silicon carbide (SiC) diode as a neutron detector that can be used in harsh environments such as nuclear reactor cores and spent fuel. The radiation tolerance of the SiC detector was studied in the present work. Especially, the effect of a metal electrode on the radiation tolerance of the SiC detector was studied. Four different types of SiC detectors were fabricated, and the operation properties of the detectors were measured and compared before and after neutron irradiations of 2.16 × 1015 n/cm2 and 5.40 × 1017 n/cm2. From the comparison, the detector with a Ti/Au electrode structure showed the highest radiation tolerance among detectors. A detector assembly was fabricated using two types of SiC p-i-n diode detectors: one containing 6LiF and the other without it. Signals from the detectors were measured in the current mode to minimize the noise of the detector. Signal currents from detectors were measured for neutron fluxes ranging from 5.54 × 106 n/cm2 s to 2.86 × 108 n/cm2 s and gamma doses up to 100 Gy/h.

  9. 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.

  10. Performance of a lead-scintillation-fiber calorimeter designed as an active beam shield for the VENUS detector

    NASA Astrophysics Data System (ADS)

    Takasaki, Fumihiko; Utsumi, M.; Fukui, T.; Narita, Y.; Hosoda, N.; Hirose, T.; Chiba, M.

    1992-11-01

    We made a cylindrical calorimeter which consisted of plastic scintillating fibers and lead. This calorimeter was designed to serve as an active beam shield for the VENUS detector [1] at the TRISTAN electron-positron collider [2]. This device has been successfully used as a beam background shield and as a luminosity monitor of the VENUS detector.

  11. Radiation effects on epoxy/carbon-fiber composite

    NASA Astrophysics Data System (ADS)

    Hoffman, E. N.; Skidmore, T. E.

    2009-07-01

    Carbon fiber-reinforced bisphenol-A epoxy matrix composite was evaluated for gamma radiation resistance. The composite was exposed to total gamma doses of 0.5, 1.0, and 2.0 MGy. Irradiated and baseline samples were tested for tensile strength, hardness and evaluated using Fourier transform infra-red spectroscopy and differential scanning calorimetry for structural changes. Scanning electron microscopy was used to evaluate microstructural behavior. Mechanical testing of the composite bars revealed no apparent change in modulus, strain to failure, or fracture strength after exposures. However, testing of only the epoxy matrix revealed changes in hardness, thermal properties, and spectroscopy results with increasing gamma irradiation. The results quantify the changes in the epoxy within the composite as a result of exposure to gamma radiation at doses relevant to service.

  12. 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 μm 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.

  13. 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.

  14. 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)

  15. Directional neutron detectors for use with 14 MeV neutrons :fiber scintillation methods for directional neutron detection.

    SciTech Connect

    Sunnarborg, Duane A.; Peel, Justin D.; Mascarenhas, Nicholas; Mengesha, Wondwosen

    2005-10-01

    Current Joint Test Assembly (JTA) neutron monitors rely on knock-on proton type detectors that are susceptible to X-rays and low energy gamma rays. We investigated two novel plastic scintillating fiber directional neutron detector prototypes. One prototype used a fiber selected such that the fiber width was less than 2.1mm which is the range of a proton in plastic. The difference in the distribution of recoil proton energy deposited in the fiber was used to determine the incident neutron direction. The second prototype measured both the recoil proton energy and direction. The neutron direction was determined from the kinematics of single neutron-proton scatters. This report describes the development and performance of these detectors.

  16. Design and development of a low-cost fiber-optic hydrogen detector

    SciTech Connect

    Benson, D.K.; Tracy, C.E.; Bechinger, C.

    1996-10-01

    A cost-effective detector for hydrogen gas leaks will be needed in many hydrogen-fueled technologies of the future. The hydrogen-fueled automobile may require hydrogen leak sensors in several locations and their cost could be prohibitive if conventional sensor technology is used. This project is directed at the development of low-cost fiber-optic (FO) hydrogen gas detectors that could provide adequate sensitivity, response speeds and reliability in an automobile application. A new, faster sensor design was invented that relies upon the resonant absorption of light at a beveled facet on the end of the optical fiber. The resonance occurs when the incident light strikes the metal coated facet at an angle just above the critical angle for total internal reflection. The evanescent wave stimulates resonant absorption by free electrons in the metal to produce a so-called surface-plasmon (SP). An overcoat of thin tungsten oxide on top of the metal film is designed to provide an optical wave-guide for light at the surface plasmon resonance. The two layer coating produces a coupled resonance at the SP wavelength that is very sensitive to the optical constants of the tungsten oxide. When hydrogen reacts with the tungsten oxide the resonance frequency shifts and this shift is detected in the spectrum of the reflected light beam. The facets are angled at 45 degrees to the fiber axis so as to reflect the light back along the fiber with a doubling of the SP absorption from the double reflection. A facet perpendicular to the fiber axis produces a reflected signal that is not affected by hydrogen that is used to produce an internal reference signal for comparison to the resonance, hydrogen-sensitive signal. The ratio of these two signals cancels out noise due to variation in the transmittance of the optical fiber. A patent application has been filed for this new design and a small business partner has formed a CRADA with NREL to develop a commercial detector based upon it.

  17. RADIATION EFFECTS ON EPOXY/CARBON FIBER COMPOSITE

    SciTech Connect

    Hoffman, E; Eric Skidmore, E

    2008-12-12

    The Department of Energy Savannah River Site vitrifies nuclear waste incident to defense programs through its Defense Waste Processing Facility (DWPF). The piping in the DWPF seal pot jumper configuration must withstand the stresses during an unlikely but potential deflagration event, and maintain its safety function for a 20-year service life. Carbon fiber-reinforced epoxy composites (CFR) were proposed for protection and reinforcement of piping during such an event. The proposed CFR materials have been ASME-approved (Section XI, Code Case N-589-1) for post-construction maintenance and is DOT-compliant per 49CFR 192 and 195. The proposed carbon fiber/epoxy composite reinforcement system was originally developed for pipeline rehabilitation and post-construction maintenance in petrochemical, refineries, DOT applications and other industries. The effects of ionizing radiation on polymers and organic materials have been studied for many years. The majority of available data are based on traditional exposures to gamma irradiation at high dose rates ({approx}10,000 Gy/hr) allowing high total dose within reasonable test periods and general comparison of different materials exposed at such conditions. However, studies in recent years have shown that degradation of many polymers are sensitive to dose rate, with more severe degradation often observed at similar or even lower total doses when exposed to lower dose rates. This behavior has been primarily attributed to diffusion-limited oxidation which is minimized during very high dose rate exposures. Most test standards for accelerated aging and nuclear qualification of components acknowledge these limitations. The results of testing to determine the radiation resistance and microstructural effects of gamma irradiation exposure on a bisphenol-A based epoxy matrix composite reinforced with carbon fibers are presented. This work provides a foundation for a more extensive evaluation of dose rate effects on advanced epoxy

  18. A scintillating-fiber 14-MeV neutron detector on TFTR during DT operation

    SciTech Connect

    Wurden, G.A.; Chrien, R.E.; Barnes, C.W.; Sailor, W.C.; Roquemore, A.L.; Lavelle, M.J.; O`Gara, P.M.; Jordan, R.J.

    1994-07-01

    A compact 14-MeV neutron detector using an array of scintillating fibers has been tested on the TFTR tokamak under conditions of a high gamma background. This detector uses a fiber-matrix geometry, a magnetic field-insensitive phototube with an active HV base and pulse-height discrimination to reject low-level pulses from 2.5 MeV neutron and intense gammas. Laboratory calibrations have been performed at EG&G Las Vegas using a pulsed DT neutron generator and a 30 kCi {sup 60}Co source as background, at PPPL using DT neutron sources, and at LANL using an energetic deuterium beam and target at a tandem Van de Graaff accelerator. During the first high power DT shots on TFTR in December 1993, the detector was 15.5 meters from the torus in a large collimator. For a rate of 1 {times} 10{sup 18} n/sec from the tokamak, it operated in an equivalent background of 1 {times} 10{sup 10} gammas/cm{sup 2}/sec ({approximately}4 mA current drain) at a DT count rate of 200 kHz.

  19. CONCORD: comparison of cosmic radiation detectors in the radiation field at aviation altitudes

    NASA Astrophysics Data System (ADS)

    Meier, Matthias M.; Trompier, François; Ambrozova, Iva; Kubancak, Jan; Matthiä, Daniel; Ploc, Ondrej; Santen, Nicole; Wirtz, Michael

    2016-05-01

    Space weather can strongly affect the complex radiation field at aviation altitudes. The assessment of the corresponding radiation exposure of aircrew and passengers has been a challenging task as well as a legal obligation in the European Union for many years. The response of several radiation measuring instruments operated by different European research groups during joint measuring flights was investigated in the framework of the CONCORD (COmparisoN of COsmic Radiation Detectors) campaign in the radiation field at aviation altitudes. This cooperation offered the opportunity to measure under the same space weather conditions and contributed to an independent quality control among the participating groups. The CONCORD flight campaign was performed with the twin-jet research aircraft Dassault Falcon 20E operated by the flight facility Oberpfaffenhofen of the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, DLR). Dose rates were measured at four positions in the atmosphere in European airspace for about one hour at each position in order to obtain acceptable counting statistics. The analysis of the space weather situation during the measuring flights demonstrates that short-term solar activity did not affect the results which show a very good agreement between the readings of the instruments of the different institutes.

  20. The effects of ionizing radiation on fiber optic systems and components for use in mobile platforms

    NASA Astrophysics Data System (ADS)

    Reddy, Mahesh; Krinsky, Jeff

    1991-02-01

    Many applications for fiber optic components and systems exist in mobile platforms. Some of the mobile platforms will be expected to operate through or survive exposure to ionizing radiation. Construction of systems that can survive the required radiation environments requires special design considerations. This paper describes the effects of ionizing radiation on some fiber optic components and systems for use in mobile platforms, and an example of transient radiation test data on a prototype analog two wavelength referenced system is presented.

  1. 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.

  2. Experimental investigation of the radiation shielding of a MCP detector in the radiation environment near Europa

    NASA Astrophysics Data System (ADS)

    Tulej, Marek; Wurz, Peter; Meyer, Stefan; Lasi, Davide; Lüthi, Matthias; Galli, André; Piazza, Daniele; Desorgher, Laurent; Hajdas, Wojciech; Reggiani, Davide; Karlsson, Stefan; Kalla, Leif

    2016-04-01

    The Neutral Ion Mass spectrometer (NIM) is one of the six instruments in the Particle Environmental Package (PEP) designed for the JUICE mission of ESA to the Jupiter system. NIM will conduct detailed measurements of chemical composition of Jovian moon exospheres and is equipped with a sensitive MCP ion detector. To maintain high sensitivity of the NIM instrument, background signals arising from the presence of a large background of penetrating radiation (mostly high-energy electrons and protons) in Jupiter's magnetosphere have to be minimised. We investigate the performance of a layered-Z radiation shield, an Al-Ta-Al sandwich, as a potential shielding against high-energy electrons. The experimental investigations were performed at the PiM1 beam line of the High Intensity Proton Accelerator Facilities located at the Paul Scherrer Institute (PSI), Villigen, Switzerland. The facility delivers a particle beam containing e,  and  with an adjustable momentum ranging from 17.5 to 345 MeV/c. The measurements of the induced radiation background generated during the interaction of primary particles with Al-Ta-Al sandwich were conducted by beam diagnostic methods and a MCP detector. Diagnostic methods provided for the characterisation of the beam parameters (beam geometry, flux and intensity) and identification of individual particles in the primary beam and in the flux of secondary particles. The MCP detector measurements provided information on the effects of radiation and the results of these measurements define the performance of the shielding material in reducing the background arising from penetrating radiation. In parallel, we performed modelling studies using GEANT 4 and GRASS methods to identify products of the interaction and predict their fluxes and particle rates at the MCP detector. Combination of the experiment and modelling studies yields detailed characterisation of the radiation effects produced by the interaction of the incident e- in the

  3. Characterization of a gated fiber-optic-coupled detector for application in clinical electron beam dosimetry

    SciTech Connect

    Tanyi, James A.; Nitzling, Kevin D.; Lodwick, Camille J.; Huston, Alan L.; Justus, Brian L.

    2011-02-15

    Purpose: Assessment of the fundamental dosimetric characteristics of a novel gated fiber-optic-coupled dosimetry system for clinical electron beam irradiation. Methods: The response of fiber-optic-coupled dosimetry system to clinical electron beam, with nominal energy range of 6-20 MeV, was evaluated for reproducibility, linearity, and output dependence on dose rate, dose per pulse, energy, and field size. The validity of the detector system's response was assessed in correspondence with a reference ionization chamber. Results: The fiber-optic-coupled dosimetry system showed little dependence to dose rate variations (coefficient of variation {+-}0.37%) and dose per pulse changes (with 0.54% of reference chamber measurements). The reproducibility of the system was {+-}0.55% for dose fractions of {approx}100 cGy. Energy dependence was within {+-}1.67% relative to the reference ionization chamber for the 6-20 MeV nominal electron beam energy range. The system exhibited excellent linear response (R{sup 2}=1.000) compared to reference ionization chamber in the dose range of 1-1000 cGy. The output factors were within {+-}0.54% of the corresponding reference ionization chamber measurements. Conclusions: The dosimetric properties of the gated fiber-optic-coupled dosimetry system compare favorably to the corresponding reference ionization chamber measurements and show considerable potential for applications in clinical electron beam radiotherapy.

  4. A Fiber-Optic Neutron Detector for a Drive-By Scenario

    SciTech Connect

    Miley, H.S.

    1999-03-30

    The measurement scenario of a neutron source driving by a detector has been evaluated. It is possible to use PNNL lithium-loaded fiber optics to measure the source, even at reasonably high speeds. A detector sufficient to detect the neutrons from the source at a high confidence level can be produced in a compact and robust configuration for a reasonable cost. In addition, the PNNL solution measures gamma-ray signals and will effectively add the function of a proximity sensor, lower the false-alarm rate, and allow discrimination between certain neutron source scenarios. Finally, the need for definition of confidence levels (both the method of computation and the required false alarm probability), emplacement form-factor, and electronic interface is required of a potential user to revise or customize the design outlined in this paper.

  5. Fiber optic inclination detector system having a weighted sphere with reference points

    DOEpatents

    Cwalinski, Jeffrey P.

    1995-01-01

    A fiber optic inclination detector system for determining the angular displacement of an object from a reference surface includes a simple mechanical transducer which requires a minimum number of parts and no electrical components. The system employs a single light beam which is split into two light beams and provided to the transducer. Each light beam is amplitude modulated upon reflecting off the transducer to detect inclination. The power values associated with each of the reflected light beams are converted by a pair of photodetectors into voltage signals, and a microprocessor manipulates the voltage signals to provide a measure of the angular displacement between the object and the reference surface.

  6. Line-scanning fiber bundle endomicroscopy with a virtual detector slit.

    PubMed

    Hughes, Michael; Yang, Guang-Zhong

    2016-06-01

    Coherent fiber bundles can be used to relay the image plane from the distal tip of an endomicroscope to an external confocal microscopy system. The frame rate is therefore determined by the speed of the microscope's laser scanning system which, at 10-20 Hz, may be undesirably low for in vivo clinical applications. Line-scanning allows an increase in the frame rate by an order of magnitude in exchange for some loss of optical sectioning, but the width of the detector slit cannot easily be adapted to suit different imaging conditions. The rolling shutter of a CMOS camera can be used as a virtual detector slit for a bench-top line-scanning confocal microscope, and here we extend this idea to endomicroscopy. By synchronizing the camera rolling shutter with a scanning laser line we achieve confocal imaging with an electronically variable detector slit. This architecture allows us to acquire every other frame with the detector slit offset by a known distance, and we show that subtracting this second image leads to improved optical sectioning. PMID:27375942

  7. Line-scanning fiber bundle endomicroscopy with a virtual detector slit

    PubMed Central

    Hughes, Michael; Yang, Guang-Zhong

    2016-01-01

    Coherent fiber bundles can be used to relay the image plane from the distal tip of an endomicroscope to an external confocal microscopy system. The frame rate is therefore determined by the speed of the microscope’s laser scanning system which, at 10-20 Hz, may be undesirably low for in vivo clinical applications. Line-scanning allows an increase in the frame rate by an order of magnitude in exchange for some loss of optical sectioning, but the width of the detector slit cannot easily be adapted to suit different imaging conditions. The rolling shutter of a CMOS camera can be used as a virtual detector slit for a bench-top line-scanning confocal microscope, and here we extend this idea to endomicroscopy. By synchronizing the camera rolling shutter with a scanning laser line we achieve confocal imaging with an electronically variable detector slit. This architecture allows us to acquire every other frame with the detector slit offset by a known distance, and we show that subtracting this second image leads to improved optical sectioning. PMID:27375942

  8. 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.

  9. Asymmetric devices based on carbon nanotubes as detectors of sub-THz radiation

    NASA Astrophysics Data System (ADS)

    Gayduchenko, I. A.; Fedorov, G. E.; Stepanova, T. S.; Titova, N.; Voronov, B. M.; But, D.; Coquillat, D.; Diakonova, N.; Knap, W.; Goltsman, G. N.

    2016-08-01

    Demand for efficient terahertz (THz) radiation detectors resulted in intensive study of the asymmetric carbon nanostructures as a possible solution for that problem. In this work, we systematically investigate the response of asymmetric carbon nanodevices to sub-terahertz radiation using different sensing elements: from dense carbon nanotube (CNT) network to individual CNT. We conclude that the detectors based on individual CNTs both semiconducting and quasi-metallic demonstrate much stronger response in sub-THz region than detectors based on disordered CNT networks at room temperature. We also demonstrate the possibility of using asymmetric detectors based on CNT for imaging in the THz range at room temperature. Further optimization of the device configuration may result in appearance of novel terahertz radiation detectors.

  10. Space Radiation Dosimetry with the The Radiation Assessment Detector (RAD) on the Mars Science Laboratory (MSL)

    NASA Astrophysics Data System (ADS)

    Hassler, Donald M.; Zeitlin, Cary; Wimmer-Schweingruber, Robert F.; Boehm, Eckhardt; Boettcher, Stephan; Burmeister, Soenke; Cucinotta, Francis A.; Kortmann, Onno; Martin, Cesar; Posner, Arik; Rafkin, Scot; Reitz, Guenther

    The Radiation Assessment Detector (RAD) is a compact, lightweight energetic particle an-alyzer that will fly on the NASA 2011 Mars Science Laboratory (MSL) Mission. RAD will detect and analyze energetic particle species (p, n, He, 2¡Z¡26) relevant for dosimetry on the Martian surface. The Galactic Cosmic Rays and Solar Energetic Particles produce both pri-mary and secondary radiation, with secondaries being created in both the atmosphere and the Martian regolith. Fully characterizing and understanding the surface radiation environment is fundamental to quantitatively assessing the habitability of Mars, and is an essential precursor measurement for future manned Mars missions. An extensive database to be used for calibration has been obtained for a wide range of energetic charged particle beams at the NASA Space Radiation Laboratory (NSRL) and the Heavy Ion Medical Accelerator in Chiba (HIMAC). Neutron calibration data at 5, 15, and 19 MeV were obtained at the Physikalisch-Technische Bundesanstalt. This talk will discuss the highlights of the RAD calibration campaigns and talk about what we have learned from these campaigns with respect to operating RAD on the Martian surface. We will also discuss other mission applications for RAD where dosimetry in mixed fields of energetic charged and neutral particles is needed.

  11. Monitoring of reinforced composites processed by microwave radiation using fiber-Bragg gratings

    NASA Astrophysics Data System (ADS)

    Barrera, David; Roig, Inma; Sales, Salvador; Emmerich, Rudolf

    2014-05-01

    The use of microwave radiation for curing carbon-fiber reinforced polymer materials (CFRP) can solve the nonhomogeneous heating problems when using conventional techniques based on the use of catalysts and can reduce the processing times. Optical fiber sensors have well-known advantages for Fiber Reinforced Composites (FRC) monitoring. In this paper fiber Bragg gratings (FBGs) are used for online monitoring of the residual stress and distortions produced during the microwave curing process. The CFRP samples are composed by layers of unidirectional carbon fibers and epoxy resin. The results show a very different behavior between the direction of carbon fibers and the perpendicular direction. Results are compared with the conventional processing technique.

  12. Status of radiation damage measurements in room temperature semiconductor radiation detectors

    SciTech Connect

    Franks, L.A.; James, R.B.

    1998-04-01

    The literature of radiation damage measurements on cadmium zinc telluride (CZT), cadmium telluride (CT), and mercuric iodide (HgI{sub 2}) is reviewed for the purpose of determining their applicability to space applications. CZT strip detectors exposed to intermediate energy (1.3 MeV) proton fluences exhibit increased interstrip leakage after 10{sup 10} p/cm{sup 2} and significant bulk leakage after 10{sup 12} p/cm{sup 2}. CZT exposed to 200 MeV protons shows a two-fold loss in energy resolution after a fluence of 5 {times} 10{sup 9} p/cm{sup 2} in thick (3 mm) planar devices but little effect in 2 mm devices. No energy resolution effects were noted from moderated fission spectrum neutrons after fluences up to 10{sup 10} n/cm{sup 2}, although activation was evident. CT detectors show resolution losses after fluences of 3 {times} 10{sup 9} p/cm{sup 2} at 33 MeV for chlorine-doped detectors. Indium doped material may be more resistant. Neutron exposures (8 MeV) caused resolution losses after fluences of 2 {times} 10{sup 10} n/cm{sup 2}. Mercuric iodide has been studied with intermediate energy protons (10 to 33 MeV) at fluences up to 10{sup 12} p/cm{sup 2} and with 1.5 GeV protons at fluences up to 1.2 {times} 10{sup 8} p/cm{sup 2}. Neutron exposures at 8 MeV have been reported at fluences up to 10{sup 15} n/cm{sup 2}. No radiation damage was found under these irradiation conditions.

  13. 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.

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

    DOEpatents

    Whited, Richard C.

    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.

  15. Investigation of possibility of creation of radiation resistance sensors for physical information based on fiber materials

    NASA Astrophysics Data System (ADS)

    Baskov, P. B.; Chebyshov, S. B.; Kadilin, V. V.; Sakharov, V. V.; Mosyagina, I. V.

    2016-02-01

    The results of physical and material science and technological development of new materials of radiation photonics - nano- and microstructure of radiation-sensitive and radiation- resistant optical glass and fibers based on quartz are presented in the report. The possibility of their application in neutron diagnostics devices of nuclear power objects are considered. Component and construction options for the radiation-sensitive fiber and glass materials (with isotopes 10B, 6Li, Gd, ions of Nd3+, Ce3+ etc.), in which radiation resistance is achieved through the organization of areas of "drain" and annihilation of radiation-induced defects are considered.

  16. Fiber coupled single photon receivers based on superconducting detectors for quantum communications and quantum cryptography

    NASA Astrophysics Data System (ADS)

    Smirnov, K. V.; Vachtomin, Yu. B.; Ozhegov, R. V.; Pentin, I. V.; Slivinskaya, E. V.; Korneev, A. A.; Goltsman, G. N.

    2008-11-01

    At present superconducting detectors become increasingly attractive for various practical applications. In this paper we present results on the depelopment of fiber coupled receiver systems for the registration of IR single photons, optimized for telecommunication and quantum-cryptography. These receiver systems were developed on the basis of superconducting single photon detectors (SSPD) of VIS and IR wavelength ranges. The core of the SSPD is a narrow (~100 nm) and long (~0,5 mm) strip in the form of a meander which is patterned from a 4-nm-thick NbN film (TC=10-11 K, jC=~5-7•106 A/cm2); the sensitive area dimensions are 10×10 μm2. The main problem to be solved while the receiver system development was optical coupling of a single-mode fiber (9 microns in diameter) with the SSPD sensitive area. Characteristics of the developed system at the optical input are as follows: quantum efficiency >10 % (at 1.3 μm), >4 % (at 1.55 μm) dark counts rate <=1 s-1; duration of voltage pulse <=5 ns; jitter <=40 ps. The receiver systems have either one or two identical channels (for the case of carrying out correlation measurements) and are made as an insert in a helium storage Dewar.

  17. Photon Identification with Segmented Germanium Detectors in Low Radiation Environments

    SciTech Connect

    Abt, I.; Caldwell, A.; Kroeninger, K.; Liu, J.; Liu, X.; Majorovits, B.; Stelzer, F.

    2007-03-28

    Effective identification of photon-induced events is essential for a new generation of double beta-decay experiments. One such experiment is the GERmanium Detector Array, GERDA, located at the INFN Gran Sasso National Laboratory (LNGS) in Italy. It uses germanium, enriched in 76Ge, as source and detector, and aims at a background level of less than 10-3 counts/(kg {center_dot} keV {center_dot} y) in the region of the Q{beta}{beta}-value. Highly segmented detectors are being developed for this experiment. A detailed GEANT4 Monte Carlo study about the possibilities to identify photon--induced background was published previously. An 18-fold segmented prototype detector was tested and its performance compared with Monte Carlo predictions. The detector performed well and the agreement with the Monte Carlo is excellent.

  18. Delivery of Erbium:YAG laser radiation through side-firing germanium oxide optical fibers

    NASA Astrophysics Data System (ADS)

    Ngo, Anthony K.; Fried, Nathaniel M.

    2006-02-01

    The Erbium:YAG laser is currently being tested experimentally for endoscopic applications in urology, including more efficient laser lithotripsy and more precise incision of urethral strictures than the Holmium:YAG laser. While side-firing silica fibers are available for use with the Ho:YAG laser in urology, no such fibers exist for use with the Er:YAG laser. These applications may benefit from the availability of a side-firing, mid-infrared optical fiber capable of delivering the laser radiation at a 90-degree angle to the tissue. The objective of this study is to describe the simple construction and characterization of a side-firing germanium oxide fiber for potential use in endoscopic laser surgery. Side-firing fibers were constructed from 450-micron-core germanium oxide fibers of 1.45-m-length by polishing the distal tip at a 45-degree angle and placing a 1-cm-long protective quartz cap over the fiber tip. Er:YAG laser radiation with a wavelength of 2.94 microns, pulse duration of 300 microseconds, pulse repetition rate of 3 Hz, and pulse energies of from 5 to 550 mJ was coupled into the fibers. The fiber transmission rate and damage threshold measured 48 +/- 4 % and 149 +/- 37 mJ, respectively (n = 6 fibers). By comparison, fiber transmission through normal germanium oxide trunk fibers measured 66 +/- 3 %, with no observed damage (n = 5 fibers). Sufficient pulse energies were transmitted through the side-firing fibers for contact tissue ablation. Although these initial tests are promising, further studies will need to be conducted, focusing on assembly of more flexible, smaller diameter fibers, fiber bending transmission tests, long-term fiber reliability tests, and improvement of the fiber output spatial beam profile.

  19. Organic liquid scintillation detector shape and volume impact on radiation portal monitors

    NASA Astrophysics Data System (ADS)

    Paff, Marc G.; Clarke, Shaun D.; Pozzi, Sara A.

    2016-07-01

    We have developed and tested a radiation portal monitor using organic liquid scintillation detectors. In order to optimize our system designs, neutron measurements were carried out with three organic liquid scintillation detectors of different shapes and sizes, along with a 3He radiation portal monitor (RPM) as a reference. The three liquids tested were a 7.62 cm diameter by 7.62 cm length cylindrical active volume organic liquid scintillation detector, a 12.7 cm diameter by 12.7 cm length cylindrical active volume organic liquid scintillation detector, and a 25 cm by 25 cm by 10 cm "paddle" shaped organic liquid scintillation detector. Background and Cf-252 neutron measurements were recorded to allow for a comparison of neutron intrinsic efficiencies as well as receiver operating characteristics (ROC) curves between detectors. The 12.7 cm diameter cylindrical active volume organic liquid scintillation detector exhibited the highest intrinsic neutron efficiency (54%) of all three liquid scintillators. An ROC curve analysis for a heavily moderated Cf-252 measurement showed that using the 12.7 cm diameter by 12.7 cm length cylindrical active volume Eljen EJ309 organic liquid scintillation detector would result in the fewest needed detector units in order to achieve a near 100% positive neutron alarm rate while maintaining a better than 1 in 10,000 false alarm rate on natural neutron background. A small number of organic liquid scintillation detectors could therefore be a valid alternative to 3He in some RPM applications.

  20. Improved performance of GaAs radiation detectors

    SciTech Connect

    Nava, F.; Vanni, P.; Bertuccio, G.

    1996-12-31

    Gallium arsenide (GaAs) offers an attractive choice for room temperature X- and {gamma}-ray detectors. However performance of SI LEC bulk GaAs detectors is at present limited by the short carrier lifetime and by the diode breakdown occurring as soon as the electric field reaches the back ohmic contact. We have shown that ohmic contacts based on ion implantation allowed us to go far beyond the bias voltage necessary to achieve a fully active detector. However the conventional thermal treatments (850 {degrees}C, 30 s) required to anneal the damage induced by ion implantation strongly reduces the electron lifetime in the detector. Alenia has developed two improved processes (RA and RB) which avoid high temperature annealing and the consequent electron lifetime reduction. With the new detectors, in pixel (200x200 {mu}m{sup 2}) configuration, a charge collection efficiency (cce) of 90 % for 59.5 keV X-rays and a FWHM of 3.35 keV has been achieved at room temperature. These features, thickness, applied voltage, cce and FWRM are suitable for application of GaAs pixel detectors in medical imaging. Results obtained with of particles and X-rays at different temperatures and in a wide range of applied bias in detectors made with standard, implantated and improved processes are presented, compared and discussed.

  1. A plastic scintillating fiber position detector in vacuum for the test beam facility at BEPC II -LINAC

    NASA Astrophysics Data System (ADS)

    Ke, Zun-Jian; Li, Jia-Cai; Zhang, Shao-Ping; An, Guang-Peng; Tang, Xing-Hua; Yang, Tao

    2012-01-01

    Two plastic scintillating fiber position detectors for charged particles have been designed, built and installed inside the vacuum tube near two sides of the DM2 deflection magnet on the E3 beam line of the test beam facility at the BEPC-LINAC. A one-dimensional position resolution of ~1 mm with a sensitive area of 60 mm×60 mm has been obtained for this detector.

  2. 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.

  3. 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

  4. 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.

  5. Method for mapping charge pulses in semiconductor radiation detectors

    SciTech Connect

    Prettyman, T.H.

    1998-12-01

    An efficient method for determining the distribution of charge pulses produced by semiconductor detectors is presented. The method is based on a quasi-steady-state model for semiconductor detector operation. A complete description of the model and underlying assumptions is given. Mapping of charge pulses is accomplished by solving an adjoint carrier continuity equation. The solution of the adjoint equation yields Green`s function, a time- and position-dependent map that contains all possible charge pulses that can be produced by the detector for charge generated at discrete locations (e.g., by gamma-ray interactions). Because the map is generated by solving a single, time-dependent problem, the potential for reduction in computational effort over direct mapping methods is significant, particularly for detectors with complex electrode structures. In this paper, the adjoint equation is derived and the mapping method is illustrated for a simple case.

  6. Measurement of gamma and neutron radiations inside spent fuel assemblies with passive detectors

    NASA Astrophysics Data System (ADS)

    Viererbl, L.; Lahodová, Z.; Voljanskij, A.; Klupák, V.; Koleška, M.; Cabalka, M.; Turek, K.

    2011-10-01

    During operation of a fission nuclear reactor, many radionuclides are generated in fuel by fission and activation of 235U, 238U and other nuclides present in the assembly. After removal of a fuel assembly from the core, these radionuclides are sources of different types of radiation. Gamma and neutron radiation emitted from an assembly can be non-destructively detected with different types of detectors. In this paper, a new method of measurement of radiation from a spent fuel assembly is presented. It is based on usage of passive detectors, such as alanine dosimeters for gamma radiation and track detectors for neutron radiation. Measurements are made on the IRT-2M spent fuel assemblies used in the LVR-15 research reactor. During irradiation of detectors, the fuel assembly is located in a water storage pool at a depth of 6 m. Detectors are inserted into central hole of the assembly, irradiated for a defined time interval, and after the detectors removed from the assembly, gamma dose or neutron fluence are evaluated. Measured profiles of gamma dose rate and neutron fluence rate inside of the spent fuel assembly are presented. This measurement can be used to evaluate relative fuel burn-up.

  7. Trap influence on the performance of gallium arsenide radiation detectors

    SciTech Connect

    Castaldini, A.; Cavallini, A.; Polenta, L.; Canali, C.; Nava, F.; Papa, C. del

    1996-12-31

    Ohmic contacts play an important role in the performance of LEC gallium arsenide particle detectors since they possibly control the injection of charge carriers. Contact characteristics have been compared and related to electrically active defects induced during contact preparation and to the detector efficiency. The electric field distribution has also been analyzed. Spectroscopic investigations have put into evidence that the contact fabrication process significantly influences the trap density whilst it does not change their signatures.

  8. Evidence of Dopant Type-Inversion and Other Radiation Damage Effects of the CDF Silicon Detectors

    SciTech Connect

    Martinez-Ballarin, Roberto

    2010-06-01

    The aim of this document is to study the effect of radiation damage on the silicon sensors. The reflection of the effect of radiation can be observed in two fundamental parameters of the detector: the bias current and the bias voltage. The leakage current directly affects the noise, while the bias voltage is required to collect the maximum signal deposited by the charged particle.

  9. 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.

  10. Calculable blackbody radiation as a source for the determination of the spectral responsivity of THz detectors

    NASA Astrophysics Data System (ADS)

    Gutschwager, B.; Monte, C.; Delsim-Hashemi, H.; Grimm, O.; Hollandt, J.

    2009-08-01

    The spectral responsivity of the detector is important for the layout and quantitative interpretation of spectroscopic experiments. In the terahertz (THz) spectral range the knowledge of the total (integral) responsivity of a detector, as well as its spectral distribution, is often insufficient. PTB determined the spectral irradiance responsivity of two THz detectors, a pyroelectric DLATGS detector working at room temperature and a silicon-composite bolometer working at 4 K, in the wavelength range from 62 µm (4.82 THz) to 1340 µm (0.22 THz) with temperature radiation from blackbody radiators. Our approach is to use two THz cavity radiators in combination with THz bandpass filters to provide calculable spectral irradiances, according to Planck's law of radiation, at several wavelength bands in the THz spectral range. One cavity radiator is working at an adjustable fixed temperature in the range from 15 °C to 90 °C while the other cavity radiator operates at LN2 temperature. The radiation of the two cavity radiators is alternately imaged on the detector via a gold-coated chopper wheel. Hereby the background radiation is cancelled and also the necessary modulation for the lock-in detection is provided. The cavity of the high temperature radiator is coated with a dedicated paint providing high wall emissivity in the FIR and THz spectral range to ensure true blackbody behaviour of the radiator. The bottom of the low temperature radiator consists of THz absorber foam providing hereby also nearly blackbody behaviour. All individual filters and, additionally, the employed filter combinations are characterized for their transmittance in the entire wavelength range from 0.8 µm to 1700 µm to obtain a precise knowledge of the transmitted blackbody spectrum. The very reproducible results indicate that this setup allows a fast, simple and reliable determination of the spectral responsivity of THz detectors. In a next step, the uncertainty of this technique will be further

  11. 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.

  12. High performance fiber-coupled NbTiN superconducting nanowire single photon detectors with Gifford-McMahon cryocooler.

    PubMed

    Miki, Shigehito; Yamashita, Taro; Terai, Hirotaka; Wang, Zhen

    2013-04-22

    We present high performance fiber-coupled niobium titanium nitride superconducting nanowire single photon detectors fabricated on thermally oxidized silicon substrates. The best device showed a system detection efficiency (DE) of 74%, dark count rate of 100 c/s, and full width at half maximum timing jitter of 68 ps under a bias current of 18.0 μA with a practical Gifford-McMahon cryocooler system. We also introduced six detectors into the cryocooler and confirmed that the system DE of all detectors was higher than 67% at the dark count rate of 100 c/s.

  13. Fiber-optic thermometry using thermal radiation from Tm end doped SiO{sub 2} fiber sensor

    SciTech Connect

    Morita, Kentaro; Katsumata, Toru; Komuro, Shuji; Aizawa, Hiroaki

    2014-04-15

    Fiber-optic thermometry based on temperature dependence of thermal radiation from Tm{sup 3+} ions was studied using Tm end doped SiO{sub 2} fiber sensor. Visible light radiation peaks due to f-f transition of Tm{sup 3+} ion were clearly observed at λ = 690 and 790 nm from Tm end doped SiO{sub 2} fibers sensor at the temperature above 600 °C. Thermal radiation peaks are assigned with f-f transition of Tm{sup 3+} ion, {sup 1}D{sub 2}-{sup 3}H{sub 6}, and {sup 1}G{sub 4}-{sup 3}H{sub 6}. Peak intensity of thermal radiation from Tm{sup 3+} ion increases with temperature. Intensity ratio of thermal radiation peaks at λ = 690 nm against that at λ = 790 nm, I{sub 790/690}, is suitable for the temperature measurement above 750 °C. Two-dimensional temperature distribution in a flame is successfully evaluated by Tm end doped SiO{sub 2} fiber sensor.

  14. Radiation tolerance of the FOXFET biasing scheme for AC-coupled Si microstrip detectors

    SciTech Connect

    Bacchetta, N.; Gotra, Yu. ); Bisello, D.; Da Ros, R.; Giraldo, A. Univ. di Padova . Dipt. di Fisica); Canali, C. Univ. di Modena . Facolta di Ingegneria); Fuochi, P.G. ); Fusaro, G. . Dept. di Elettronica e Informatica); Paccagnella, A. Univ. di Cagliari . Instituto di Elettrotecnica); Verzellesi, G. Univ. di Padova . Dept. di Elettronica e Informatica)

    1993-12-01

    The radiation response of FOXFETs has been studied for proton, gamma and neutron exposures. The punch-through behavior, which represents the normal FET operating conditions in Si microstrip detectors, has been found to be much less sensitive to radiation damage than threshold voltage. The device performance has been elucidated by means of two-dimensional simulations. The main radiation effects have been also taken into account in the numerical analysis and separately examined.

  15. Electromagnetic and nuclear radiation detector using micromechanical sensors

    DOEpatents

    Thundat, Thomas G.; Warmack, Robert J.; Wachter, Eric A.

    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.

  16. 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.

  17. 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.

  18. Monte Carlo code G3sim for simulation of plastic scintillator detectors with wavelength shifter fiber readout

    NASA Astrophysics Data System (ADS)

    Mohanty, P. K.; Dugad, S. R.; Gupta, S. K.

    2012-04-01

    A detailed description of a compact Monte Carlo simulation code "G3sim" for studying the performance of a plastic scintillator detector with wavelength shifter (WLS) fiber readout is presented. G3sim was developed for optimizing the design of new scintillator detectors used in the GRAPES-3 extensive air shower experiment. Propagation of the blue photons produced by the passage of relativistic charged particles in the scintillator is treated by incorporating the absorption, total internal, and diffuse reflections. Capture of blue photons by the WLS fibers and subsequent re-emission of longer wavelength green photons is appropriately treated. The trapping and propagation of green photons inside the WLS fiber is treated using the laws of optics for meridional and skew rays. Propagation time of each photon is taken into account for the generation of the electrical signal at the photomultiplier. A comparison of the results from G3sim with the performance of a prototype scintillator detector showed an excellent agreement between the simulated and measured properties. The simulation results can be parametrized in terms of exponential functions providing a deeper insight into the functioning of these versatile detectors. G3sim can be used to aid the design and optimize the performance of scintillator detectors prior to actual fabrication that may result in a considerable saving of time, labor, and money spent.

  19. Coherent radiation of relativistic electrons in dielectric fibers in the millimeter wavelength range

    NASA Astrophysics Data System (ADS)

    Naumenko, G. A.; Potylitsyn, A. P.; Bleko, V. V.; Soboleva, V. V.

    2015-02-01

    The generation of visible light by a relativistic electron beam in dielectric fibers was considered in X. Artru and C. Ray, Nucl. Inst. Meth. B 309, 4 (2013), where the characteristics of radiation induced in a fiber by the electromagnetic field of a relativistic charged particle were studied and it was emphasized that they differ from those in the traditional mechanisms of radiation such as transition and diffraction. We have experimentally studied the characteristics of such a radiation in the millimeter wavelength range. It has been shown that radiation can be generated through different mechanisms depending on the geometry of the position of a fiber with respect to the trajectory of the charged particle. Fibers have been shown to be promising for nondestructive diagnostics of accelerator beams.

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

    DOEpatents

    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.

  1. 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.

  2. Fabrication process development for high-purity germanium radiation detectors with amorphous semiconductor contacts

    NASA Astrophysics Data System (ADS)

    Looker, Quinn

    High-purity germanium (HPGe) radiation detectors are well established as a valuable tool in nuclear science, astrophysics, and nuclear security applications. HPGe detectors excel in gamma-ray spectroscopy, offering excellent energy resolution with large detector sizes for high radiation detection efficiency. Although a robust fabrication process has been developed, improvement is needed, especially in developing electrical contact and surface passivation technology for position-sensitive detectors. A systematic study is needed to understand how the detector fabrication process impacts detector performance and reliability. In order to provide position sensitivity, the electrical contacts are segmented to form multiple electrodes. This segmentation creates new challenges in the fabrication process and warrants consideration of additional detector effects related to the segmentation. A key area of development is the creation of the electrical contacts in a way that enables reliable operation, provides low electronic noise, and allows fine segmentation of electrodes, giving position sensitivity for radiation interactions in the detector. Amorphous semiconductor contacts have great potential to facilitate new HPGe detector designs by providing a thin, high-resistivity surface coating that is the basis for electrical contacts that block both electrons and holes and can easily be finely segmented. Additionally, amorphous semiconductor coatings form a suitable passivation layer to protect the HPGe crystal surface from contamination. This versatility allows a simple fabrication process for fully passivated, finely segmented detectors. However, the fabrication process for detectors with amorphous semiconductors is not as highly developed as for conventional technologies. The amorphous semiconductor layer properties can vary widely based on how they are created and these can translate into varying performance of HPGe detectors with these contacts. Some key challenges include

  3. Gamma radiation influence on silica optical fibers measured by optical backscatter reflectometry and Brillouin sensing technique

    NASA Astrophysics Data System (ADS)

    Wosniok, A.; Sporea, D.; Neguţ, D.; Krebber, K.

    2016-05-01

    We have studied the influence of gamma rays on physical properties of different commercially available silica optical fibers stepwise irradiated up to a total dose of 100 kGy. The detection of radiation-induced changes in silica glass offers the possibility of using selected optical fibers as distributed radiation sensors. The measurements performed by us were based on optical backscatter reflectometry and Brillouin distributed sensing. The measurement methods enable an analysis of radiation-induced modification of the group refractive index and density of the optical fibers. The most distinct physical effect observed by us concerns the increase of the optical attenuation with rising total radiation doses. Quantitative measurement results indicate a crucial impact of fiber dopants on radiation-induced physical and sensory characteristics of silica optical fibers affected by differences in fiber fabrication techniques. Based on the obtained results, the suitability of distributed Brillouin sensing for dosimetry applications seems to be improved by modifying the refractive index profile of the fiber core.

  4. Cerenkov light spectrum in an optical fiber exposed to a photon or electron radiation therapy beam

    SciTech Connect

    Lambert, Jamil; Yin Yongbai; McKenzie, David R.; Law, Sue; Suchowerska, Natalka

    2009-06-20

    A Cerenkov signal is generated when energetic charged particles enter the core of an optical fiber. The Cerenkov intensity can be large enough to interfere with signals transmitted through the fiber. We determine the spectrum of the Cerenkov background signal generated in a poly(methyl methacrylate) optical fiber exposed to photon and electron therapeutic beams from a linear accelerator. This spectral measurement is relevant to discrimination of the signal from the background, as in scintillation dosimetry using optical fiber readouts. We find that the spectrum is approximated by the theoretical curve after correction for the wavelength dependent attenuation of the fiber. The spectrum does not depend significantly on the angle between the radiation beam and the axis of the fiber optic but is dependent on the depth in water at which the fiber is exposed to the beam.

  5. Improvement of terahertz field effect transistor detectors by substrate thinning and radiation losses reduction.

    PubMed

    Coquillat, Dominique; Marczewski, Jacek; Kopyt, Pawel; Dyakonova, Nina; Giffard, Benoit; Knap, Wojciech

    2016-01-11

    Phenomena of the radiation coupling to the field effect transistors based terahertz (THz) detectors are studied. We show that in the case of planar metal antennas a significant portion of incoming radiation, instead of being coupled to the transistors, is coupled to an antenna substrate leading to responsivity losses and/or cross-talk effects in the field effect based THz detector arrays. Experimental and theoretical investigations of the responsivity versus substrate thickness are performed. They clearly show how to minimize the losses by the detector/ array substrate thinning. In conclusion simple quantitative rules of losses minimization by choosing a proper substrate thickness of field effect transistor THz detectors are presented for common materials (Si, GaAs, InP, GaN) used in semiconductor technologies. PMID:26832258

  6. Effects of high energy radiation on the mechanical properties of epoxy-graphite fiber reinforced composites

    NASA Technical Reports Server (NTRS)

    Fornes, R. E.; Gilbert, R. D.; Memory, J. D.

    1985-01-01

    In an effort to elucidate the changes in molecular structural and mechanical properties of epoxy/graphite fiber composites upon exposure to ionizing radiation in a simulated space environment, spectroscopic and surface properties of tetraglycidyl-4,4'-diamino diphenyl methane (TGDDM) red with diamino diphenyl sulfone (DDS) and T-300 graphite fiber were investigated following exposure to ionizing radiation. Cobalt-60 gamma radiation and 1/2 MeV electrons were used as radiation sources. The system was studied using electron spin resonance (ESR) spectroscopy, infrared absorption spectroscopy, contact angle measurements, and electron spectroscopy for chemical analysis.

  7. The impacts of ageing effects due to radiation burden on optical fiber couplers

    NASA Astrophysics Data System (ADS)

    Perecar, F.; Marcinka, O.; Bednarek, L.; Lucki, M.; Liner, A.; Hajek, L.; Papes, M.; Jaros, J.; Vasinek, V.

    2015-08-01

    The paper discuss about accelerated ageing of optical fiber elements in their burdened with gamma radiation. In addition to the destruction of coating materials, gamma radiation has its effect on the internal structure of the optical fiber. It is necessary to specify the changes in the optical coupler and find out why these changes occur. This article contains experimental measurement of the impact of gamma radiation Cobalt-60 on the optical couplers of various split performance ratio. The couplers were exposed to gradually increasing doses of 60Co. Measurements are focused on the overall distribution of the energy in the core and cladding various branches of SM optical fiber couplers. This article focuses on applied research and experimental development of resources for safety operation of optical networks since monitoring of ageing substantially contributes to its security. It addresses issues of accelerated ageing of optical fiber elements in their burdened with gamma radiation. How does radiation energy of gamma radiation influence optical network elements? This effect is explored just very little bit and is yet another unanswered question. In addition to the destruction of coating materials, gamma radiation has its effect on the internal structure of the optical fiber. It is necessary to specify the changes in the optical coupler and find out why these changes occur. This article contains experimental measurement of the impact of gamma radiation Cobalt-60 on the optical couplers of various split performance ratio. Optical passive components, couplers, were exposed to gradually increasing doses of 60Co. Measurements are focused on the overall distribution of the energy of LP01 mode in the core and cladding various branches of SM optical fiber couplers. Graphical and mathematical detect changes in the dissemination of energy coupler after single doses of gamma radiation are useful to understand the phenomenon of accelerated ageing elements of optical networks in

  8. 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

  9. PTOSL response of commercial Al2O3:C detectors to ultraviolet radiation.

    PubMed

    Gronchi, Claudia C; Caldas, Linda V E

    2013-04-01

    The photo-transferred optically stimulated luminescence (PTOSL) technique using Al2O3:C detectors has been suggested as a good option for ultraviolet (UV) radiation dosimetry. The objective of this work was to study the PTOSL response of Al2O3:C InLight detectors and the OSL microStar reader of Landauer. The parameters such as radiation pre-dose, optical treatment time and UV illumination time were determined. The detectors presented a satisfactory stimulus of PTOSL signals when they were subjected to a preconditioning procedure with gamma radiation (1 Gy pre-dose), 30 min of optical treatment (to empty the shallow traps) and 30 min of UV illumination from an artificial source. PMID:22887115

  10. SiC detectors for radiation sources characterization and fast plasma diagnostic

    NASA Astrophysics Data System (ADS)

    Cannavò, A.; Torrisi, L.

    2016-09-01

    Semiconductor detectors based on SiC have been investigated to characterize the radiations (photons and particles) emitted from different sources, such as radioactive sources, electron guns, X-ray tubes and laser-generated plasmas. Detectors show high response velocity, low leakage current, high energy gap and high radiation hardness. Their high detection efficiency permits to use the detectors in spectroscopic mode and in time-of-flight (TOF) approach, generally employed to monitor low and high radiation fluxes, respectively. Using the laser start signal, they permit to study the properties of the generated plasma in vacuum by measuring accurately the particle velocity and energy using pulsed lasers at low and high intensities. Possible applications will be reported and discussed.

  11. 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.

  12. High-resolution detectors for medical applications and synchrotron radiation research

    NASA Astrophysics Data System (ADS)

    Babichev, E. A.; Baru, S. E.; Grigoriev, D. N.; Groshev, V. R.; Leonov, V. V.; Papushev, P. A.; Porosev, V. V.; Savinov, G. A.; Shayakhmetov, V. R.; Shekhtman, L. I.; Tikhonov, Yu. A.; Ukraintsev, Yu. G.; Yurchenko, Yu. B.

    2011-02-01

    In the present report, we summarize our experience in the development of high-resolution position sensitive gas detectors for medicine and synchrotron radiation experiments at Budker Institute of Nuclear Physics for the last years. We have designed several versions of Multistrip Ionisation Chambers with a channel pitch varying from 0.4 down to 0.1 mm. The high quantum efficiency (>65%) of these detectors allow its application in high quality diagnostic imaging. The detector with 0.1 mm strip pitch and 20 atm pressure of Xe demonstrates the best possible DQE and spatial resolution for gaseous detectors in a wide range of X-ray energies. Additionally, the initial results of feasibility study of the detector for beam position monitoring for Heavy Ion Therapy System are presented too.

  13. Internal Electric Field Behavior of Cadmium Zinc Telluride Radiation Detectors Under High Carrier Injection

    SciTech Connect

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

    2010-10-26

    The behavior of the internal electric-field of nuclear-radiation detectors substantially affects the detector's performance. We investigated the distribution of the internal field in cadmium zinc telluride (CZT) detectors under high carrier injection. We noted the build-up of a space charge region near the cathode that produces a built-in field opposing the applied field. Its presence entails the collapse of the electric field in the rest of detector, other than the portion near the cathode. Such a space-charge region originates from serious hole-trapping in CZT. The device's operating temperature greatly affects the width of the space-charge region. With increasing temperature from 5 C to 35 C, its width expanded from about 1/6 to 1/2 of the total depth of the detector.

  14. On the use of a single-fiber multipoint plastic scintillation detector for 192Ir high-dose-rate brachytherapy

    PubMed Central

    Therriault-Proulx, François; Beddar, Sam; Beaulieu, Luc

    2013-01-01

    Purpose: The goal of this study was to prove the feasibility of using a single-fiber multipoint plastic scintillation detector (mPSD) as an in vivo verification tool during 192Ir high-dose-rate brachytherapy treatments. Methods: A three-point detector was built and inserted inside a catheter-positioning template placed in a water phantom. A hyperspectral approach was implemented to discriminate the different optical signals composing the light output at the exit of the single collection optical fiber. The mPSD was tested with different source-to-detector positions, ranging from 1 to 5 cm radially and over 10.5 cm along the longitudinal axis of the detector, and with various integration times. Several strategies for improving the accuracy of the detector were investigated. The device's accuracy in detecting source position was also tested. Results: Good agreement with the expected doses was obtained for all of the scintillating elements, with average relative differences from the expected values of 3.4 ± 2.1%, 3.0 ± 0.7%, and 4.5 ± 1.0% for scintillating elements from the distal to the proximal. A dose threshold of 3 cGy improved the general accuracy of the detector. An integration time of 3 s offered a good trade-off between precision and temporal resolution. Finally, the mPSD measured the radioactive source positioning uncertainty to be no more than 0.32 ± 0.06 mm. The accuracy and precision of the detector were improved by a dose-weighted function combining the three measurement points and known details about the geometry of the detector construction. Conclusions: The use of a mPSD for high-dose-rate brachytherapy dosimetry is feasible. This detector shows great promise for development of in vivo applications for real-time verification of treatment delivery. PMID:23718599

  15. Fast response amplitude scintillation detector for X-ray synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Dementyev, E. N.; Sheromov, M. A.; Sokolov, A. S.

    1986-05-01

    The present paper describes a scintillation detector for X-ray synchrotron radiation. This detector has been created on the basis of a scintillator and a photoelectron multiplier (FEU-130) and its construction allows one to use the specific features of the time characteristics of synchrotron radiation from the electron storage ring. In a given range of amplitudes, the detector electronics makes a 64-channel amplitude analysis of the FEU-130 signal strobed by the revolution frequency of an electron bunch in the storage ring ( f0 = 818 kHz). There is the possibility of operating the detector at high intensities of the monochromatic radiation incident on the scintillator. Such a possibility is directly provided by the time structure of SR and is not realizable with the use of other X-ray sources. The detector will find wide application in studies on X-ray structural analysis, transmission and fluorescent EXAFS- and XANES-spectroscopy, transmission scanning microscopy and microtomography, calibration of X-ray detectors and as a monitor on SR beams from the storage ring VEPP-4.

  16. Fiber Bragg gratings in the radiation environment: Change under the influence of radiolytic hydrogen

    SciTech Connect

    Butov, Oleg V. Golant, Konstantin M.; Shevtsov, Igor' A.; Fedorov, Artem N.

    2015-08-21

    The change of the transmission spectra of fiber Bragg gratings written in the optical fibers, whose silica cores are doped with either germanium or nitrogen, is studied experimentally under the influence of gamma-radiation. The transmission spectra in the neighborhood of the resonance (Bragg) wavelengths were regularly recorded “in-situ” in the course of irradiation during 24 days. For this purpose, uncoated gratings were placed in a pool near the spent fuel rods of a nuclear reactor. The fibers with the gratings written in them were in immediate contact with water. The estimated total absorbed radiation dose of the fibers is approximately 5 MGy. Molecular hydrogen, which is produced by radiolysis of water and penetrates into the core of silica fiber, is found to interact with the defects of Ge-doped silica induced by gamma-radiation, thereby causing a strong impact on the parameters of the spectrum of the Bragg gratings. On the contrary, in the case of gratings inscribed in N-doped silica fibers, the hydrogen molecules interact with defects induced in the course of laser UV exposure during the grating writing only. The possible subsequent formation of additional defects in N-doped silica under the influence of gamma-radiation has no substantial impact on the transmission spectra of Bragg gratings, which remained stable. The obtained results suggest that a small amount of molecular hydrogen resided in the fiber core is the main source of radiation instability of Ge-doped fiber Bragg grating sensors in radiation environments. These hydrogen molecules can remain in the Bragg gratings, in particular, after the inscription process in the hydrogen-loaded fibers.

  17. Fiber Bragg gratings in the radiation environment: Change under the influence of radiolytic hydrogen

    NASA Astrophysics Data System (ADS)

    Butov, Oleg V.; Golant, Konstantin M.; Shevtsov, Igor'A.; Fedorov, Artem N.

    2015-08-01

    The change of the transmission spectra of fiber Bragg gratings written in the optical fibers, whose silica cores are doped with either germanium or nitrogen, is studied experimentally under the influence of gamma-radiation. The transmission spectra in the neighborhood of the resonance (Bragg) wavelengths were regularly recorded "in-situ" in the course of irradiation during 24 days. For this purpose, uncoated gratings were placed in a pool near the spent fuel rods of a nuclear reactor. The fibers with the gratings written in them were in immediate contact with water. The estimated total absorbed radiation dose of the fibers is approximately 5 MGy. Molecular hydrogen, which is produced by radiolysis of water and penetrates into the core of silica fiber, is found to interact with the defects of Ge-doped silica induced by gamma-radiation, thereby causing a strong impact on the parameters of the spectrum of the Bragg gratings. On the contrary, in the case of gratings inscribed in N-doped silica fibers, the hydrogen molecules interact with defects induced in the course of laser UV exposure during the grating writing only. The possible subsequent formation of additional defects in N-doped silica under the influence of gamma-radiation has no substantial impact on the transmission spectra of Bragg gratings, which remained stable. The obtained results suggest that a small amount of molecular hydrogen resided in the fiber core is the main source of radiation instability of Ge-doped fiber Bragg grating sensors in radiation environments. These hydrogen molecules can remain in the Bragg gratings, in particular, after the inscription process in the hydrogen-loaded fibers.

  18. 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

  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. Single photon counting pixel detectors for synchrotron radiation experiments

    NASA Astrophysics Data System (ADS)

    Toyokawa, H.; Broennimann, Ch.; Eikenberry, E. F.; Henrich, B.; Kawase, M.; Kobas, M.; Kraft, P.; Sato, M.; Schmitt, B.; Suzuki, M.; Tanida, H.; Uruga, T.

    2010-11-01

    At the Paul Scherrer Institute PSI an X-ray single photon counting pixel detector (PILATUS) based on the hybrid-pixel detector technology was developed in collaboration with SPring-8. The detection element is a 320 or 450 μm thick silicon sensor forming pixelated pn-diodes with a pitch of 172 μm×172 μm. An array of 2×8 custom CMOS readout chips are indium bump-bonded to the sensor, which leads to 33.5 mm×83.8 mm detective area. Each pixel contains a charge-sensitive amplifier, a single level discriminator and a 20 bit counter. This design realizes a high dynamic range, short readout time of less than 3 ms, a high framing rate of over 200 images per second and an excellent point-spread function. The maximum counting rate achieves more than 2×10 6 X-rays/s/pixel.

  1. 11th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors

    NASA Astrophysics Data System (ADS)

    The primary goal of the Conference is to review the present status of the Semiconductor Detector apparatuses in the field of High Energy or Astroparticle Physics. In both cases the requests on the detector systems are very demanding: very large instrumented surface, radiation hardness and high reliability. Part of the talks will be devoted to describe the pixel and microstrip silicon-based detectors presently operated at the LHC experiments. The operational experience and the detector performance with the p-p runs 2009-2012 will be discussed. Another fraction of the talks will be devoted to plans for upgrading the LHC tracker detectors for the next runs of the LHC and on strategies for future high luminosity upgrades of the LHC. Studies on radiation hardness of silicon materials, diamond-based detectors, innovative solutions for optical links and power device components will be reported. The astroparticle detectors activity will also be reviewed. Semiconductor applications in different fields, like medical imaging, radioactive monitoring and one quantum-physics experiment will be rapidly touched.

  2. Detectors

    DOEpatents

    Orr, Christopher Henry; Luff, Craig Janson; Dockray, Thomas; Macarthur, Duncan Whittemore; Bounds, John Alan; Allander, Krag

    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.

  3. Fiber-optic thermometer application of thermal radiation from rare-earth end-doped SiO{sub 2} fiber

    SciTech Connect

    Katsumata, Toru Morita, Kentaro; Komuro, Shuji; Aizawa, Hiroaki

    2014-08-15

    Visible light thermal radiation from SiO{sub 2} glass doped with Y, La, Ce, Pr, Nd, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu were studied for the fiber-optic thermometer application based on the temperature dependence of thermal radiation. Thermal radiations according to Planck's law of radiation are observed from the SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu at the temperature above 1100 K. Thermal radiations due to f-f transitions of rare-earth ions are observed from the SiO{sub 2} fibers doped with Nd, Dy, Ho, Er, Tm, and Yb at the temperature above 900 K. Peak intensities of thermal radiations from rare-earth doped SiO{sub 2} fibers increase sensitively with temperature. Thermal activation energies of thermal radiations by f-f transitions seen in Nd, Dy, Ho, Er, Tm, and Yb doped SiO{sub 2} fibers are smaller than those from SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu. Thermal radiation due to highly efficient f-f transitions in Nd, Dy, Ho, Er, Tm, and Yb ions emits more easily than usual thermal radiation process. Thermal radiations from rare-earth doped SiO{sub 2} are potentially applicable for the fiber-optic thermometry above 900 K.

  4. [Effects of ionizing radiation on scintillators and other particle detectors]. Conference summary

    SciTech Connect

    Proudfoot, J.

    1992-09-01

    It is my task to summarise the great variety of topics (covering a refreshing mix of physics, chemistry and technology) presented at this conference, which has focused on the effects of ionising radiation on scintillators and other particle detectors. One of the reasons and the central interest of many of the participants was the use of such detectors in experiments at two future large hadron colliders: the Superconducting Super Collider to be operating outside of Dallas in the United States by the turn of the decade and its European counterpart the Large Hadron Collider to be operating outside of Geneva in Switzerland on a similar time scale. These accelerators are the ``apple of the high energy physicist`s eye.`` Their goal is to uncover the elusive Higgs particle and thereby set the cornerstone in our current knowledge of elementary particle interactions. This is the Quest, and from this lofty height the presentations rapidly moved on to the specific questions of experimental science: how such an experiment is carried out; why radiation damage is an issue; how radiation damage affects detectors; which factors affect radiation damage characteristics; which factors are not affected by radiation damage; and how better detectors may be constructed. These were the substance of this conference.

  5. Correction-less dosimetry of nonstandard photon fields: a new criterion to determine the usability of radiation detectors.

    PubMed

    Kamio, Y; Bouchard, H

    2014-09-01

    In the IAEA-AAPM dosimetry formalism, detector measurements in general nonstandard conditions are corrected using the factor k(f(clin),f(msr))(Q(clin),Q(msr)). This factor needs to be evaluated on a case-by-case basis which is difficult to accomplish in practice. The present paper aims to provide a method that allows neglecting correction factors for small and composite IMRT fields by first determining a radiation detector's usability in these fields. Detailed models of nine radiation detectors are built: four ionization chambers (NE2571, A12, A1SL, A14), three small field detectors (PTW31018 microLion, PTW60003 natural diamond, PTW60012 unshielded diode) and two near water-equivalent detectors (alanine, W1 scintillating fiber). Using the egs_chamber Monte Carlo code, dose response functions at 6 MV and 25 MV are sampled for each detector and their corresponding volume of water. These functions are then used with a newly derived criterion to evaluate an upper bound ξ(f(ns),f(msr))(Q(ns),Q(msr)) on the variable ε(f(ns),f(msr))(Q(ns),Q(msr)) if no field collimation/modulation occurs over a given perturbation zone. The variable ε(f(ns),f(msr))(Q(ns),Q(msr)) is defined as the absolute value of the relative deviation from unity of a nonstandard field quality correction factor k(f(ns),f(msr))(Q(ns),Q(msr)). Using the same criterion, perturbation zones are evaluated by finding the smallest field size allowed for correction-less dosimetry with a given tolerance ξ(f(ns),f(msr))(Q(ns),Q(msr)). For composite fields, the sensitivity of detectors to the non-uniformity of virtual symmetric collapsed beams over regions of interest specified by the criterion is studied to estimate an upper bound ξ ̃(f(ns),f(ref))(Q(ns),Q) on ε(f(ns),f(ref))(Q(ns),Q) for a given beam flatness. Finally, a newly defined perturbation function is used to minimize the perturbations of the microLion chamber through density compensation. The theoretical criterion shows good agreement with full

  6. Information-Based Development of New Radiation Detectors

    SciTech Connect

    Ferris, Kim F.; Webb-Robertson, Bobbie-Jo M.; Jones, Dumont M.

    2006-12-31

    With our present concern for a secure environment, the development of new radiation detection materials has focused on the capability of identifying potential radiation sources at increased sensitivity levels. As the initial framework for a materials-informatics approach to radiation detection materials, we have explored the use of both supervised (Support Vector Machines – SVM and Linear Discriminant Analysis – LDA) and unsupervised (Principal Component Analysis – PCA) learning methods for the development of structural signature models. Application of these methods yields complementary results, both of which are necessary to reduce parameter space and variable degeneracy. Using a crystal structure classification test, the use of the nonlinear SVM significantly increases predictive performance, suggesting trade-offs between smaller descriptor spaces and simpler linear models.

  7. 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.

  8. 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 γ-rays, electrons, protons and α-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.

  9. Active radiation hardening of Tm-doped silica fiber based on pump bleaching.

    PubMed

    Xing, Ying-bin; Zhao, Nan; Liao, Lei; Wang, Yi-bo; Li, Hai-qing; Peng, Jing-gang; Yang, Lv-yun; Dai, Neng-li; Li, Jin-yan

    2015-09-21

    Tm-doped fiber laser or amplifier can be applied in varied adverse environments. In this work, we demonstrate the pump bleaching of Tm-doped silica fiber with 793nm pump source under gamma-ray irradiation in the range 50Gy-675Gy. The recovery time, the fiber slope efficiency and the fiber cladding absorption spectra after irradiation and bleaching have been measured. It is found that the recovery time and radiation induce absorption are positively associated with doses, however, the fiber slope efficiency of irradiated TDF and bleached TDF are both negatively correlated with doses. Based on the simulation of the fiber core temperature, the probable mechanism of pump bleaching is also discussed.

  10. Optimized digital filtering techniques for radiation detection with HPGe detectors

    NASA Astrophysics Data System (ADS)

    Salathe, Marco; Kihm, Thomas

    2016-02-01

    This paper describes state-of-the-art digital filtering techniques that are part of GEANA, an automatic data analysis software used for the GERDA experiment. The discussed filters include a novel, nonlinear correction method for ballistic deficits, which is combined with one of three shaping filters: a pseudo-Gaussian, a modified trapezoidal, or a modified cusp filter. The performance of the filters is demonstrated with a 762 g Broad Energy Germanium (BEGe) detector, produced by Canberra, that measures γ-ray lines from radioactive sources in an energy range between 59.5 and 2614.5 keV. At 1332.5 keV, together with the ballistic deficit correction method, all filters produce a comparable energy resolution of ~1.61 keV FWHM. This value is superior to those measured by the manufacturer and those found in publications with detectors of a similar design and mass. At 59.5 keV, the modified cusp filter without a ballistic deficit correction produced the best result, with an energy resolution of 0.46 keV. It is observed that the loss in resolution by using a constant shaping time over the entire energy range is small when using the ballistic deficit correction method.

  11. Transient radiation-induced effects on solid core microstructured optical fibers.

    PubMed

    Girard, S; Ouerdane, Y; Bouazaoui, M; Marcandella, C; Boukenter, A; Bigot, L; Kudlinski, A

    2011-10-24

    We report transient radiation-induced effects on solid core microstructured optical fibers (MOFs). The kinetics and levels of radiation-induced attenuation (RIA) in the visible and near-infrared part of the spectrum (600 nm-2000 nm) were characterized. It is found that the two tested MOFs, fabricated by the stack-and-draw technique, present a good radiation tolerance. Both have similar geometry but one has been made with pure-silica tubes and the other one with Fluorine-doped silica tubes. We compared their pulsed X-ray radiation sensitivities to those of different classes of conventional optical fibers with pure-silica-cores or cores doped with Phosphorus or Germanium. The pulsed radiation sensitivity of MOFs seems to be mainly governed by the glass composition whereas their particular structure does not contribute significantly. Similarly for doped silica fibers, the measured spectral dependence of RIA for the MOFs cannot be correctly reproduced with the various absorption bands associated with the Si-related defects identified in the literature. However, our analysis confirms the preponderant role of self-trapped holes with their visible and infrared absorption bands in the transient behaviors of pure-silica of F-doped fibers. The results of this study showed that pure-silica or fluorine-doped MOFs, which offers specific advantages compared to conventional fibers, are promising for use in harsh environments due to their radiation tolerance.

  12. Detectors and electronics for real time measurement of radiation dose and quality using the variance method

    NASA Astrophysics Data System (ADS)

    Hsu, Wen-Hsing

    The product of the radiation dose and radiation quality indicates the biological consequences of radiation exposure. Therefore, quantifying both radiation dose and radiation quality is important to biological experiments as well as radiation protection. A small, specialized amplifier based on commercial ICs was developed to measure the radiation dose and quality in real-time using a microdosimetric detector, operated in the current mode, and the variance method. The random nature of radiation induces variance in the dose (in a small volume such as that of cell or DNA) for a specific radiation field that is proportional to the radiation quality. The charges from the microdosimetric detector, operated in the current mode, were repeatedly collected for a fixed period of time for 20 cycles of 100 integrations, and processed by the specialized amplifier to produce signals of pulse height between 0 and 10 volts. These signals with various amplitudes, which are proportional to the channel number, were then recorded by the MCA and stored in a computer. FORTRAN programs written in this study then calculated the average dose and the average dose variance from the stored data. Benchmarks of different brand's ICs were conducted to select a component with the best performance versus cost. The specialized amplifier showed the following characteristics: low input capacitance, low output impedance, adjustable integration time for controlling the amount of charge collected from the detector, linearity of system response to input currents, adjustable gain control, and low background noise. Standardized procedures of constructing a functional device (the specialized amplifier) were established, including arrangements of circuit diagram, processing of a printed circuit board, and construction of an aluminum-shielding box that served as a united ground point. In addition, procedures for determining the inner dimensions of the detector using radiography are also presented along with

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

    DOEpatents

    Chiles, Marion M.; Mihalczo, John T.; Blakeman, Edward D.

    1989-02-07

    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.

  14. 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.

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

    DOEpatents

    Chiles, Marion M.; Mihalczo, John T.; Blakeman, Edward D.

    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.

  16. Intercomparison of luminescence detectors for space radiation dosimetry within Proton-ICCHIBAN experiments

    NASA Astrophysics Data System (ADS)

    Uchihori, Yukio; Ploc, Ondrej; Yasuda, Nakahiro; Berger, Thomas; Hajek, Michael; Kodaira, Satoshi; Benton, Eric; Ambrozova, Iva; Kitamura, Hisashi

    2012-07-01

    Luminescence detectors for space radiation dosimetry are frequently used to estimate personal and environmental doses in the International Space Station and other space vehicles. Detector responses for cosmic rays and their secondaries were investigated for a long time and it is well-known that luminescence detectors have dependencies of response on LET (Linear Energy Transfer). Some of luminescence detectors show over-response to gamma rays (used for routine calibration) and others have similar responses to gamma rays. But, because of lack of sufficient and reliable calibration data in the low LET region (about 1 keV/μm), it is the responses of these detectors at LET is poorly known. Protons make up the dominant portion of the fluence from space radiation, so the LET region corresponding to energetic protons must be characterized very well. For that purpose, calibration and intercomparison experiments were performed using relatively low energy (30 to 80 MeV) proton beams at the National Institute of Radiological Sciences, Chiba, Japan. In this paper, the results of these intercomparison experiments, including high energy protons and light ions, are reported and illustrate the response of luminescence detectors in the low LET region. This research will help improve our understanding of space dosimeters and reliable dose measurement for astronauts and cosmonauts in low earth orbit.

  17. 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.

  18. 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.

    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

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

    PubMed

    Kubančák, Ján; Ambrožová, Iva; Brabcová, Kateřina Pachnerová; Jakůbek, Jan; Kyselová, Dagmar; Ploc, Ondřej; Bemš, Július; Štěpán, 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.

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

    PubMed

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

    2008-10-01

    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.

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

    PubMed

    Kubančák, Ján; Ambrožová, Iva; Brabcová, Kateřina Pachnerová; Jakůbek, Jan; Kyselová, Dagmar; Ploc, Ondřej; Bemš, Július; Štěpán, 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

  2. 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.

  3. 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…

  4. 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.

  5. [The use of a detector of the extremely weak radiation as a variometer of gravitation field].

    PubMed

    Gorshkov, E S; Bondarenko, E G; Shapovalov, S N; Sokolovskiĭ, V V; Troshichev, O A

    2001-01-01

    It was shown that the detector of extremely weak radiation with selectively increased sensitivity to the nonelectromagnetic, including the gravitational component of the spectrum of active physical fields can be used as the basis for constructing a variometer of gravitational field of a new type.

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

    NASA Astrophysics Data System (ADS)

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

    2004-05-01

    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.

  7. Characteristics of fabricated si PIN-type radiation detectors on cooling temperature

    NASA Astrophysics Data System (ADS)

    Kim, Han Soo; Jeong, Manhee; Kim, Young Soo; Lee, Dong Hun; Cho, Seung Yeon; Ha, Jang Ho

    2015-06-01

    Si PIN photodiode radiation detectors with three different active areas (3×3 mm2, 5×5 mm2, and 10×10 mm2) were designed and fabricated at the Korea Atomic Energy Research Institute (KAERI) for low energy X- and gamma-ray detection. In Si-based semiconductor radiation detectors, one of the noise sources is thermal noise, which degrades their energy resolution performance. In this study, the temperature effects on the energy resolution were investigated using a 3×3 mm2 active area PIN photodiode radiation detector using a Thermoelectric Module (TEM) from room temperature to -23 °C. Energy resolutions from 25 keV auger electrons to 81 keV gamma-ray from a Ba-133 calibration source were measured and compared at every 10 °C interval. At -23 °C, energy resolutions were improved by 15.6% at 25 keV, 4.0% at 31 keV, and 1.2% at 81 keV in comparison with resolutions at room temperature. CsI(Tl)/PIN photodiode radiation detectors were also fabricated for relatively high energy gamma-ray detection. Energy resolutions for Cs-137, Co-60, and Na-22 sources were measured and compared with the spectral responsivity.

  8. Weakly superconducting, thin-film structures as radiation detectors.

    NASA Technical Reports Server (NTRS)

    Kirschman, R. K.

    1972-01-01

    Measurements were taken with weakly superconducting quantum structures of the Notarys-Mercereau type, representing a thin superconductor film with a short region that is weakened in the sense that its transition temperature is lower than in the remaining portion of the film. The structure acts as a superconducting relaxation oscillator in which the supercurrent increases with time until the critical current of the weakened section is attained, at which moment the supercurrent decays and the cycle repeats. Under applied radiation, a series of constant-voltage steps appears in the current-voltage curve, and the size of the steps varies periodically with the amplitude of applied radiation. Measurements of the response characteristics were made in the frequency range of 10 to 450 MHz.

  9. 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.

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

    PubMed

    Kyselová, D; Ambrožová, I; Krist, P; Kubančák, 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

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

    PubMed

    Kyselová, D; Ambrožová, I; Krist, P; Kubančák, 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.

  12. Improved mid infrared detector for high spectral or spatial resolution and synchrotron radiation use

    NASA Astrophysics Data System (ADS)

    Faye, Mbaye; Bordessoule, Michel; Kanouté, Brahim; Brubach, Jean-Blaise; Roy, Pascale; Manceron, Laurent

    2016-06-01

    When using bright, small effective size sources, such as synchrotron radiation light beam, for broadband spectroscopy at spectral or spatial high resolution for mid-IR FTIR measurements, a marked detectivity improvement can be achieved by setting up a device matching the detector optical étendue to that of the source. Further improvement can be achieved by reducing the background unmodulated flux and other intrinsic noise sources using a lower temperature cryogen, such as liquid helium. By the combined use of cooled apertures, cold reimaging optics, filters and adapted detector polarization, and preamplification electronics, the sensitivity of a HgCdTe photoconductive IR detector can be improved by a significant factor with respect to standard commercial devices (more than one order of magnitude on average over 6-20 μm region) and the usable spectral range extended to longer wavelengths. The performances of such an optimized detector developed on the AILES Beamline at SOLEIL are presented here.

  13. Improved mid infrared detector for high spectral or spatial resolution and synchrotron radiation use.

    PubMed

    Faye, Mbaye; Bordessoule, Michel; Kanouté, Brahim; Brubach, Jean-Blaise; Roy, Pascale; Manceron, Laurent

    2016-06-01

    When using bright, small effective size sources, such as synchrotron radiation light beam, for broadband spectroscopy at spectral or spatial high resolution for mid-IR FTIR measurements, a marked detectivity improvement can be achieved by setting up a device matching the detector optical étendue to that of the source. Further improvement can be achieved by reducing the background unmodulated flux and other intrinsic noise sources using a lower temperature cryogen, such as liquid helium. By the combined use of cooled apertures, cold reimaging optics, filters and adapted detector polarization, and preamplification electronics, the sensitivity of a HgCdTe photoconductive IR detector can be improved by a significant factor with respect to standard commercial devices (more than one order of magnitude on average over 6-20 μm region) and the usable spectral range extended to longer wavelengths. The performances of such an optimized detector developed on the AILES Beamline at SOLEIL are presented here. PMID:27370438

  14. 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.

  15. An electronically-collimated portable gamma-ray detector for locating environmental radiation sources

    NASA Astrophysics Data System (ADS)

    Matthews, Kenneth L., II; Smith, Blair M.; Lackie, Adam W.; Hill, William H., Jr.; Wang, Wei-Hsung; Cherry, Michael L.

    2006-08-01

    We are developing a detector system for locating environmental radiation sources. The design emphasizes compact size (ideally hand-held), wide field of view and high detection efficiency, and uses cadmium-zinc-telluride (CZT) detectors and electronic collimation via Compton-scatter detection. The detector design is a 6-sided box with a primary scatter detector on one end. GEANT4 simulations, allowing variations of detector parameters and source energies/locations, provided performance estimates. A partial prototype, using 16x16-pixel 38x38x5-mm 3 CZT detectors, was developed and tested. Two methods to calculate source direction in real-time from the Compton scatter data were evaluated: (1) filtered backprojection of cones onto a sphere; (2) intersection with the sphere of bounding boxes circumscribed around the cones. Simulation results of the 6-sided box with the current CZT modules indicated 1-5% of incident gamma rays produce valid direction angles, with an angular resolution of ~15°. The directional algorithms allowed a FOV (directional error <10°) of approximately +/-60°. The direction algorithms converge on a source direction estimate in as few as 100 detected events. With improvements in detector energy and spatial resolution, reasonable performance seems achievable for a range of radioisotopes, e.g., from Am-241 through Co-60.

  16. Investigation of GEM-Micromegas detector on X-ray beam of synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Zhang, Yu-Lian; Qi, Hui-Rong; Hu, Bi-Tao; Fan, Sheng-Nan; Wang, Bo; Liu, Mei; Zhang, Jian; Liu, Rong-Guang; Chang, Guang-Cai; Liu, Peng; Ouyang, Qun; Chen, Yuan-Bo; Yi, Fu-Ting

    2014-04-01

    To reduce the discharge of the standard bulk Micromegas and GEM detectors, a GEM-Micromegas detector was developed at the 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 significantly reduce the effect of the discharge. At the same gain, the spark probability of the GEM-Micromegas detector can be reduced to a factor 0.01 compared to the standard Micromegas detector, and an even higher gain could be obtained. This paper describes the performance of the X-ray beam detector that 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. This indicates that the GEM-Micromegas detector has an energy response capability in an energy range from 6 keV to 20 keV and it could work better than the standard bulk-Micromegas.

  17. Optimizing ZnS/6LiF scintillators for wavelength-shifting-fiber neutron detectors

    SciTech Connect

    Crow, Lowell; Funk, Loren L; Hannan, Bruce W; Hodges, Jason P; Riedel, Richard A; Wang, Cai-Lin

    2016-01-01

    In this paper we compare the performance of grooved and flat ZnS/6LiF scintillators in a wavelength shifting-fiber (WLSF) detector. Flat ZnS/6LiF scintillators with the thickness L=0.2-0.8 mm were characterized using photon counting and pulse-height analysis and compared to a grooved scintillator of approximately 0.8 mm thick. While a grooved scintillator considerably increases the apparent thickness of the scintillator to neutrons for a given coating thickness, we find that the flat scintillators perform better than the grooved scintillators in terms of both light yield and neutron detection efficiency. The flat 0.8-mm-thick scintillator has the highest light output, and it is 52% higher compared with a grooved scintillator of same thickness. The lower light output of the grooved scintillator as compared to the flat scintillator is consistent with the greater scintillator-WLSF separation and the much larger average emission angle of the grooved scintillator. We also find that the average light cone width, or photon travel-length as measured using time-of-flight powder diffraction of diamond and vanadium, decreases with increasing L in the range of L=0.6-0.8 mm. This result contrasts with the traditional Swank diffusion model for micro-composite scintillators, and could be explained by a decrease in photon diffusion-coefficient or an increase in micro-particle content in the flat scintillator matrix for the thicker scintillators.

  18. Effect of radiation-induced color centers absorption in optical fibers on fiber optic gyroscope for space application

    NASA Astrophysics Data System (ADS)

    Jin, Jing; Li, Ya; Zhang, Zu-Chen; Wu, Chun-Xiao; Song, Ning-Fang

    2016-08-01

    The effects of color centers’ absorption on fibers and interferometric fiber optical gyroscopes (IFOGs) are studied in the paper. The irradiation induced attenuation (RIA) spectra of three types of polarization-maintaining fibers (PMFs), i.e., P-doped, Ge-doped, and pure silica, irradiated at 100 Gy and 1000 Gy are measured in a wavelength range from 1100 nm to 1600 nm and decomposed according to the Gaussian model. The relationship of the color centers absorption intensity with radiation dose is investigated based on a power model. Furthermore, the effects of all color centers’ absorption on RIA and mean wavelength shifts (MWS) at 1300 nm and 1550 nm are discussed respectively. Finally, the random walk coefficient (RWC) degradation induced from RIA and the scale factor error induced by MWS of the IFOG are simulated and tested at a wavelength of 1300 nm. This research will contribute to the applications of the fibers in radiation environments. Project supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry, China.

  19. Integrated four-channel all-fiber up-conversion single-photon-detector with adjustable efficiency and dark count

    NASA Astrophysics Data System (ADS)

    Zheng, Ming-Yang; Shentu, Guo-Liang; Ma, Fei; Zhou, Fei; Zhang, Hai-Ting; Dai, Yun-Qi; Xie, Xiuping; Zhang, Qiang; Pan, Jian-Wei

    2016-09-01

    Up-conversion single photon detector (UCSPD) has been widely used in many research fields including quantum key distribution, lidar, optical time domain reflectrometry, and deep space communication. For the first time in laboratory, we have developed an integrated four-channel all-fiber UCSPD which can work in both free-running and gate modes. This compact module can satisfy different experimental demands with adjustable detection efficiency and dark count. We have characterized the key parameters of the UCSPD system.

  20. 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.

  1. Radiation-resistant erbium-doped-nanoparticles optical fiber for space applications.

    PubMed

    Thomas, Jérémie; Myara, Mikhaël; Troussellier, Laurent; Burov, Ekaterina; Pastouret, Alain; Boivin, David; Mélin, Gilles; Gilard, Olivier; Sotom, Michel; Signoret, Philippe

    2012-01-30

    We demonstrate for the first time a radiation-resistant Erbium-Doped Fiber exhibiting performances that can fill the requirements of Erbium-Doped Fiber Amplifiers for space applications. This is based on an Aluminum co-doping atom reduction enabled by Nanoparticules Doping-Process. For this purpose, we developed several fibers containing very different erbium and aluminum concentrations, and tested them in the same optical amplifier configuration. This work allows to bring to the fore a highly radiation resistant Erbium-doped pure silica optical fiber exhibiting a low quenching level. This result is an important step as the EDFA is increasingly recognized as an enabling technology for the extensive use of photonic sub-systems in future satellites.

  2. 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

  3. 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.

  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. Development of an alpha/beta/gamma detector for radiation monitoring

    SciTech Connect

    Yamamoto, Seiichi; Hatazawa, Jun

    2011-11-15

    For radiation monitoring at the site of nuclear power plant accidents such as Fukushima Daiichi, radiation detectors not only for gamma photons but also for alpha and beta particles are needed because some nuclear fission products emit beta particles and gamma photons and some nuclear fuels contain plutonium that emits alpha particles. We developed a radiation detector that can simultaneously monitor alpha and beta particles and gamma photons for radiation monitoring. The detector consists of three-layered scintillators optically coupled to each other and coupled to a photomultiplier tube. The first layer, which is made of a thin plastic scintillator (decay time: 2.4 ns), detects alpha particles. The second layer, which is made of a thin Gd{sub 2}SiO{sub 5} (GSO) scintillator with 1.5 mol.% Ce (decay time: 35 ns), detects beta particles. The third layer made of a thin GSO scintillator with 0.4 mol.% Ce (decay time: 70 ns) detects gamma photons. By using pulse shape discrimination, the count rates of these layers can be separated. With individual irradiation of alpha and beta particles and gamma photons, the count rate of the first layer represented the alpha particles, the second layer represented the beta particles, and the third layer represented the gamma photons. Even with simultaneous irradiation of the alpha and beta particles and the gamma photons, these three types of radiation can be individually monitored using correction for the gamma detection efficiency of the second and third layers. Our developed alpha, beta, and gamma detector is simple and will be useful for radiation monitoring, especially at nuclear power plant accident sites or other applications where the simultaneous measurements of alpha and beta particles and gamma photons are required.

  6. 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.

  7. Study the radiation damage effects in Si microstrip detectors for future HEP experiments

    NASA Astrophysics Data System (ADS)

    Lalwani, Kavita; Jain, Geetika; Dalal, Ranjeet; Ranjan, Kirti; Bhardwaj, Ashutosh

    2016-07-01

    Silicon (Si) detectors are playing a key role in High Energy Physics (HEP) experiments due to their superior tracking capabilities. In future HEP experiments, like upgrade of the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC), CERN, the silicon tracking detectors will be operated in a very intense radiation environment. This leads to both surface and bulk damage in Si detectors, which in turn will affect the operating performance of Si detectors. It is important to complement the measurements of the irradiated Si strip detectors with device simulation, which helps in understanding of both the device behavior and optimizing the design parameters needed for the future Si tracking system. An important ingredient of the device simulation is to develop a radiation damage model incorporating both bulk and surface damage. In this work, a simplified two-trap model is incorporated in device simulation to describe the type-inversion. Further, an extensive simulation of effective doping density as well as electric field profile is carried out at different temperatures for various fluences.

  8. Effect of Te Inclusions on the Performance of Cdznte Radiation Detectors

    SciTech Connect

    Bolotnikov, A.; Abdul-Jabbar, N; Babalola, O; Camarda, G; Cui, Y; Hossain, A; Jackson, E; Jackson, H; James, J; et. al.

    2009-01-01

    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.

  9. 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.

  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

  11. Backreflected radiation due to a propagating fiber fuse.

    PubMed

    Abedin, Kazi S; Nakazawa, Masataka; Miyazaki, Tetsuya

    2009-04-13

    The properties of backreflected light due to voids in a fiber fuse were studied using optical coherence-domain reflectometry of a damaged fiber and real-time monitoring of the electrical (RF) and optical frequency spectrum. Light reflected backward at the interface of a propagating fiber fuse acquired low-frequency broadband amplitude modulation, which can be detected remotely at the source end, using an RF spectrum analyzer. For the light backreflected during propagation of a fuse, we derived an analytical expression that well explained the spectral features observed experimentally in the RF spectrum. Finally, a novel method that allowed us to rapidly terminate the fuse propagation (in a few milliseconds) is also shown.

  12. Fiber Optic Cable Assemblies for Space Flight 2: Thermal and Radiation Effects

    NASA Technical Reports Server (NTRS)

    Ott, Melanie N.

    1998-01-01

    Goddard Space Flight Center is conducting a search for space flight worthy fiber optic cable assemblies that will benefit all projects at all of the NASA centers. This paper is number two in a series of papers being issued as a result of this task to define and qualify space grade fiber optic cable assemblies. Though to qualify and use a fiber optic cable in space requires treatment of the cable assembly as a system, it is very important to understand the design and behavior of its parts. This paper addresses that need, providing information on cable components shrinkage testing and radiation testing results from recent experiments at Goddard Space Flight Center.

  13. 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 π 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 γ conversion factor of the detectors-how many γ 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 π non-destructive apparatus.

  14. Dietary sugar beet fiber ameliorates diarrhea as an acute gamma-radiation injury in rats.

    PubMed

    Ishizuka, S; Ito, S; Kasai, T; Hara, H

    2000-09-01

    Gamma radiation induces diarrhea as an acute injury. We have studied whether ingestion of sugar beet fiber influences radiation-induced diarrhea. Abdominal irradiation with gamma rays induced diarrhea in male Wistar/ST rats from 2 to 7 days after a single sublethal dose. The body weight of the irradiated rats was decreased temporarily at 4 days after irradiation regardless of the ingestion of sugar beet fiber. At day 8, it returned to almost the same level as that of unirradiated rats. A change in daily food intake resulted in a pattern similar to that for body weight. Dietary sugar beet fiber had little significant effect on the changes in body weight and daily food intake, and its ingestion significantly decreased gamma-ray-induced diarrhea. Changes in biochemical and histological parameters in intestinal mucosa (small intestine, cecum and colon) were not greatly influenced by the ingestion of sugar beet fiber through the periods of diarrhea. It was concluded that dietary sugar beet fiber ameliorated the diarrhea induced by abdominal irradiation. We suggest that the inhibitory effect of the ingestion of sugar beet fiber is due to its effects on the luminal environment, such as support for bacterial function in the luminal contents in the colon of animals that ingest sugar beet fiber.

  15. 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.

  16. 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.

  17. Modeling of radiation damage recovery in particle detectors based on GaN

    NASA Astrophysics Data System (ADS)

    Gaubas, E.; Ceponis, T.; Pavlov, J.

    2015-12-01

    The pulsed characteristics of the capacitor-type and PIN diode type detectors based on GaN have been simulated using the dynamic and drift-diffusion models. The drift-diffusion current simulations have been implemented by employing the commercial software package Synopsys TCAD Sentaurus. The bipolar drift regime has been analyzed. The possible internal gain in charge collection through carrier multiplication processes determined by impact ionization has been considered in order to compensate carrier lifetime reduction due to radiation defects introduced into GaN material of detector.

  18. GEMGrid: a wafer post-processed GEM-like radiation detector

    NASA Astrophysics Data System (ADS)

    Blanco Carballo, V. M.; Bilevych, Y.; Chefdeville, M.; Fransen, M.; van der Graaf, H.; Salm, C.; Schmitz, J.; Timmermans, J.

    2009-09-01

    This paper presents a new wafer post-processed micropatterned gaseous radiation detector called GEMGrid. The device consists of a GEM-like structure fabricated with SU-8 photoresist directly on top of a Timepix chip with zero gap distance. The detector characteristics have been studied in several gas mixtures. The device is capable of tracking minimum ionizing particles and exhibits good energy resolution on 55Fe decays. We further show a strongly improved mechanical robustness of these GEM-like structures as compared to a pillar-supported integrated Micromegas.

  19. Evaluation of radiation interference in the Voyager Sun Sensor's cadmium sulfide detector

    NASA Technical Reports Server (NTRS)

    Clarke, T. C.; Divita, E. L.

    1978-01-01

    The simulation of radiation interference effects and the results of a radiation interference test on two Voyager Sun Sensor prototype detector assemblies are reported. The derivation of test levels and requirements are discussed and show that cobalt 60 gamma radiation is an effective and practical simulator of the ionization dose rate effects induced by high-energy electron flux incident on the spacecraft at a rate of 3.7 x 10 to the 8th e/sq cm-sec (10 rad(Si)/s) during closest approach to Jupiter. The test results provide information that is used to confirm an analytic correlation, and to predict satisfactory performance of a spacecraft sun sensing device having stringent angular resolution requirements. The measured detector response shows that at dose rates incident on the detector elements of 2 rad(Si)/sec, which is four times that expected during Jupiter encounter, the radiation-induced angle error is almost an order of magnitude less than that allowed by the acceptance criteria.

  20. Common characteristics of synchrotron radiation and light leaking from a bent optical fiber

    NASA Astrophysics Data System (ADS)

    Artru, X.; Ray, C.

    2016-07-01

    Light leaking from a bent optical fiber shares many properties with synchrotron radiation : in ray optics, both lights are emitted tangentially to a light cylinder; in wave optics, the emission mechanism involves a tunnel effect. The angular distributions of these two radiations are studied in parallel and found to be similar. The same is done for the impact parameter distributions. The latter show interference fringes of the Airy function type. The far field escaped from the fiber is calculated with the Volume Current Method. An optical system observing the impact parameter profile is proposed.

  1. Electrodrift purification of materials for room temperature radiation detectors

    DOEpatents

    James, Ralph B.; Van Scyoc, III, John M.; Schlesinger, Tuviah 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. 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.

  2. 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.

  3. Infrared imaging of cotton fibers using a focal-plane array detector

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vibrational spectroscopy studies can be used to examine the quality and structure of cotton fibers. An emerging area of research relates to the imaging of cotton fibers. Herein, we report the use of a Fourier-transform infrared (FTIR) microscope to image developing cotton fibers. Studies were perfor...

  4. Radiation tests of ATLAS full-sized n-in-n prototype detectors

    NASA Astrophysics Data System (ADS)

    Allport, P. P.; Apsimon, R. J.; Becker, C.; Bizzell, J.; Bonino, R.; Booth, P. S. L.; Boulter, B.; Carter, A. A.; Carter, J. R.; Clark, A. G.; Couyoumtzelis, C.; Goodrick, M. J.; Green, C.; Greenall, A.; Hanlon, M.; Hill, J. C.; Jackson, J. N.; Jones, T. J.; Kowalewski, R.; Macina, D.; García, S. Martí i.; Munday, D. J.; Newman-Coburn, D.; Orme, E.; O'Shea, V.; Perrin, E.; Richardson, J. D.; Riedler, P.; Robinson, D.; Roe, S.; Smith, N. A.; Thüne, R.; Turner, P. R.; Tyndel, M.; Vuaridel, B.; Wormald, M. P.; Wunstorf, R.; Wüstenfeld, J.; Wyllie, K. H.

    1998-11-01

    ATLAS Technical Proposal, CERN/LHCC/94-43 has adopted n-side read out single-sided detectors as the baseline technology for the silicon microstrips due to the anticipated radiation tolerance of such a design ATLAS Inner Detector Technical Design Report, CERN/LHCC/97-17. This results from the reasonable efficiencies anticipated for charge collection, even when the detectors are run well below the final depletion voltage. Full-sized prototypes 64×63.6 mm 2 detectors have been produced with a range of manufacturers to a common specification and shown to work well in test-beam with ATLAS electronics. A selection of detectors was also scanned in the CERN PS beam for runs of two weeks giving an integrated dose over the full surface of 2×10 14 p/cm 2. This dose corresponds to the highest charged hadron fluence expected in 10 yr of operation in ATLAS. Results are presented on these detectors both from parametric measurements and from studies using analogue LHC speed electronics. The detectors are shown to remain fully operational after these doses and to yield high signal/noise for read-out of 12 cm strip length. The performance partially depleted is also shown to match expectations and operation at down to half the final depletion voltage gives adequate efficiencies. Uncertainties in the anticipated dose and damage effects argue strongly for this additional robustness in detectors which must operate with very limited access in the hostile environment of the LHC for 10 yr.

  5. Gamma-radiation-induced degradation of actively pumped single-mode ytterbium-doped optical fibers

    NASA Astrophysics Data System (ADS)

    Singleton, B.; Petrosky, J.; Pochet, M.; Usechak, N. G.; Francis, S. A.

    2014-03-01

    The integration of optical components into the digital processing units of satellite subsystems has the potential to remove interconnect bottlenecks inherent to the volume, mass, complexity, reliability and crosstalk issues of copper-based interconnects. Assuming on-board high-bandwidth communications will utilize passive optical fibers as a communication channel, this work investigates the impact of gamma irradiation from a Co-60 source on both passive optical fibers and ytterbium-doped single-mode fibers operated as amplifiers for a 1060-nm light source. Standard optical patch cables were evaluated along with active Yb-doped double-clad fibers. Varied exposure times and signal transmission wavelengths were used to investigate the degradation of the fibers exposed to total doses above 100 krad (Si). The effect on the amplified signal gain was studied for the Yb-doped fibers. The increased attenuation in the fibers across a broad wavelength range in response to multiple levels of gamma radiation exposure along with the effect that the increased attenuation has on the actively pumped Yb-doped fiber amplifier performance, is discussed.

  6. Experimental investigation of the radiation shielding efficiency of a MCP detector in the radiation environment near Jupiter's moon Europa

    NASA Astrophysics Data System (ADS)

    Tulej, M.; Meyer, S.; Lüthi, M.; Lasi, D.; Galli, A.; Piazza, D.; Desorgher, L.; Reggiani, D.; Hajdas, W.; Karlsson, S.; Kalla, L.; Wurz, P.

    2016-09-01

    Neutral Ion Mass spectrometer (NIM) is one of the instruments in the Particle Environmental Package (PEP) designed for the JUICE mission of ESA to the Jupiter system. NIM, equipped with a sensitive MCP ion detector, will conduct detailed measurements of the chemical composition of Jovian icy moons exospheres. To achieve high sensitivity of the instrument, radiation effects due to the high radiation background (high-energy electrons and protons) around Jupiter have to be minimised. We investigate the performance of an Al-Ta-Al composite stack as a potential shielding against high-energy electrons. Experiments were performed at the PiM1 beam line of the High Intensity Proton Accelerator Facilities located at the Paul Scherrer Institute, Villigen, Switzerland. The facility delivers a particle beam containing e-, μ- and π- with momentum from 17.5 to 345 MeV/c (Hajdas et al., 2014). The measurements of the radiation environment generated during the interaction of primary particles with the Al-Ta-Al material were conducted with dedicated beam diagnostic methods and with the NIM MCP detector. In parallel, modelling studies using GEANT4 and GRAS suites were performed to identify products of the interaction and predict ultimate fluxes and particle rates at the MCP detector. Combination of experiment and modelling studies yields detailed characterisation of the radiation fields produced by the interaction of the incident e- with the shielding material in the range of the beam momentum from 17.5 to 345 MeV/c. We derived the effective MCP detection efficiency to primary and secondary radiation and effective shielding transmission coefficients to incident high-energy electron beam in the range of applied beam momenta. This study shows that the applied shielding attenuates efficiently high-energy electrons. Nevertheless, owing to nearly linear increase of the bremsstrahlung production rate with incident beam energy, above 130 MeV their detection rates measured by the MCP

  7. 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

  8. Diffuser for intravessels radiation based on plastic fiber

    NASA Astrophysics Data System (ADS)

    Pich, Justyna; Grobelny, Andrzej; Beres-Pawlik, Elzbieta

    2006-03-01

    Laser radiation is used in such contemporary medicine as: sport medicine, gynecology etc. Because of many radiations inside the system, there is a need of an element, which allows to supply the place of illness with energy. The dimensions of this element are often small and the one that meets these conditions is diffuser.

  9. 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.

  10. Improved charge collection of the buried p-i-n a-Si:H radiation detectors

    SciTech Connect

    Fujieda, I.; Cho, G.; Conti, M.; Drewery, J.; Kaplan, S.N.; Perez-Mendez, V.; Qureshi, S.; Street, R.A.; Xerox Palo Alto Research Center, CA )

    1989-09-01

    Charge collection in hydrogenated amorphous silicon (a-Si:H) radiation detectors is improved for high LET particle detection by adding thin intrinsic layers to the usual p-i-n structure. This buried p-i-n structure enables us to apply higher bias and the electric field is enhanced. When irradiated by 5.8 MeV {alpha} particles, the 5.7 {mu}m thick buried p-i-n detector with bias 300V gives a signal size of 60,000 electrons, compared to about 20,000 electrons with the simple p-i-n detectors. The improved charge collection in the new structure is discussed. The capability of tailoring the field profile by doping a-Si:H opens a way to some interesting device structures. 17 refs., 7 figs.

  11. Coherent sychrotron radiation detector for a non-invasive subpicosecond bunch length monitor

    SciTech Connect

    Krafft, G.A.; Wang, D.; Price, E.; Feldl, E.; Porterfield, D.; Wood, P.; Crowe, T.

    1995-12-31

    This CSR detector was developed to monitor nondestructively the length of a subpicosecond bunch with high sensitivity. The monitor uses a state of the art GaAs Schottky whisker diode which is operated at room temperature at a wavelength of a few hundred microns. The detector is capable of detecting radiation power as low as 10 nW, depending on wavelength. This paper describes design specifications, parameter ranges, and monitor features and also reports its performance and comparison between measurement and calculation. The measurement results are cross-compared with an independent bunch length measurement using phase modulation. It was found that the output power varies with bunch length and that detectors at shorter wavelengths are preferred.

  12. Optimal source to detector separation for extracting sub-dermal chromophores in fiber optic diffuse reflectance spectroscopy: a simulation study

    NASA Astrophysics Data System (ADS)

    Sujatha, N.; Nivetha, K. Bala; Singhal, Akshay

    2014-05-01

    Localization and determination of blood region parameters in skin tissue can serve as a valuable supplement to standard non invasive techniques, especially in accessing the degree of depth of burns on skin and for the classification of vascular malformations. Quantitative optical examination of skin local blood region requires the use of depth sensitive techniques and preferential probing for assessment of data from specific layers of skin tissue. This work incorporates the depth sensitivity of diffuse reflectance spectroscopy and optimal source to detector fiber separation for maximum reflectance collection efficiency from local blood region in skin. Monte Carlo simulation for diffuse reflectance was performed on a multi layered skin tissue model consisting of epidermis, perfused dermis and localized blood region. It was found that the slope of the spatially resolved reflectance curve plotted with respect to the source to detector separation distance in semi log scale varies with the depth of the local blood region at specific wavelengths corresponding to the absorption wavelengths of hemoglobin. From the depth information obtained from the spatially resolved reflectance data, the optimum source to detector separation (SDS) is determined for maximum collection efficiency from the chromophore layer. The results obtained from simulation suggest the design of a linearly variable source to detector separation probe for preferential analysis of the depth of a specific tissue layer and subsequent determination of optimal source to detector separation for extracting the layer information.

  13. Test and Evaluation of Fiber Optic Sensors for High-Radiation Space Nuclear Power Applications

    SciTech Connect

    Klemer, Daniel; Fielder, Robert S.; Stinson-Bagby, Kelly L.

    2004-07-01

    Fiber optic sensors can be used to measure a number of parameters, including temperature, strain, pressure and flow, for instrumentation and control of space nuclear power systems. In the past, this technology has often been rejected for use in such a high-radiation environment based on early experiments that revealed a number of degradation phenomena, including radiation-induced fiber attenuation, or 'graying', and Fiber Bragg Grating (FBG) fading and wavelength shift. However, this paper reports the results of recent experimental testing that demonstrates readability of fiber optic sensors to extremely high levels of neutron and gamma radiation. Both distributed Fiber Bragg Grating (FBG) sensors and single-point Extrinsic Fabry Perot Interferometer (EFPI) sensors were continuously monitored over a 2-month period, during which they were exposed to combined neutron and gamma radiation in both in-core and ex-core positions within a nuclear reactor. Total exposure reached approximately 2 x 10{sup 19} cm{sup -2} fast neutron (E > 1 MeV) fluence and 8.7 x 10{sup 8} Gy gamma for in-core sensors. FBG sensors were interrogated using a standard Luna Innovations FBG measurement system, which is based on optical frequency-domain reflectometer (OFDR) technology. Approximately 74% of the 19 FBG sensors located at the core centerline in the in-core position exhibited sufficient signal-to-noise ratio (SNR) to remain readable even after receiving the maximum dose. EFPI sensors were spectrally interrogated using a broadband probe source operating in the 830 nm wavelength region. While these single-point sensors failed early in the test, important additional fiber spectral transmission data was collected, which indicates that interrogation of EFPI sensors in alternate wavelength regions may allow significant improvement in sensor longevity for operation in high-radiation environments. This work was funded through a Small Business Innovative Research (SBIR) contract with the Nasa

  14. Glass-fiber-based neutron detectors for high- and low-flux environments

    NASA Astrophysics Data System (ADS)

    Bliss, Mary; Brodzinski, Ronald L.; Craig, Richard A.; Geelhood, Bruce D.; Knopf, Michael A.; Miley, Harry S.; Perkins, Richard W.; Reeder, Paul L.; Sunberg, Debra S.; Warner, Ray A.; Wogman, Ned A.

    1995-09-01

    Pacific Northwest Laboratory (PNL) has fabricated cerium-activated lithium silicate scintillating fibers via a hot-downdraw process. These fibers typically have a operational transmission length (e(superscript -1) length) of greater than 2 meters. This permits the fabrication of devices which were not possible to consider. Scintillating fibers permit conformable devices, large-area devices, and extremely small devices; in addition, as the thermal-neutron sensitive elements in a fast neutron detection system, scintillating fibers can be dispersed within moderator, improving neutron economy, over that possible with commercially available (superscript 3)He or BF(subscript 3) proportional counters. These fibers can be used for national-security applications, in medical applications, in the nuclear-power industry, and for personnel protection at experimental facilities. Data are presented for devices based on single fibers and devices made up of ribbons containing many fibers under high-and low-flux conditions.

  15. 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 λe/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.

  16. A 2D DNA lattice as an ultrasensitive detector for beta radiations.

    PubMed

    Dugasani, Sreekantha Reddy; Kim, Jang Ah; Kim, Byeonghoon; Joshirao, Pranav; Gnapareddy, Bramaramba; Vyas, Chirag; Kim, Taesung; Park, Sung Ha; Manchanda, Vijay

    2014-02-26

    There is growing demand for the development of efficient ultrasensitive radiation detectors to monitor the doses administered to individuals during therapeutic nuclear medicine which is often based on radiopharmaceuticals, especially those involving beta emitters. Recently biological materials are used in sensors in the nanobio disciplines due to their abilities to detect specific target materials or sites. Artificially designed two-dimensional (2D) DNA lattices grown on a substrate were analyzed after exposure to pure beta emitters, (90)Sr-(90)Y. We studied the Raman spectra and reflected intensities of DNA lattices at various distances from the source with different exposure times. Although beta particles have very low linear energy transfer values, the significant physical and chemical changes observed throughout the extremely thin, ∼0.6 nm, DNA lattices suggested the feasibility of using them to develop ultrasensitive detectors of beta radiations.

  17. The SNAP 27 gamma radiation spectrum obtained with a Ge/Li/ detector

    NASA Technical Reports Server (NTRS)

    Taherzadeh, M.

    1976-01-01

    The pulse height distribution, obtained experimentally using a Ge(Li) detector, was employed to determine the photon emission rate characteristic of a PuO2 fuel source known as the SNAP 27 heat source. The selfshielding parameters of the photon emitter, the efficiency of the detector and the geometry of the experiment were utilized to determine the unscattered photon emission rate of the source and the unscattered flux spectrum at a certain specified distance from the source. For the scattered part of the flux spectrum a Monte Carlo technique was employed so that the total flux spectrum could be determined at any point in the radiation field. As a result of this work, a technique was developed to obtain the unfolded radiation spectrum of the SNAP 27 heat source.

  18. 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 γ-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.

  19. 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.

  20. Fiber

    MedlinePlus

    ... it can help with weight control. Fiber aids digestion and helps prevent constipation . It is sometimes used ... fiber attracts water and turns to gel during digestion. This slows digestion. Soluble fiber is found in ...

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

    DOE PAGESBeta

    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.; et al

    2013-01-12

    We subjected device-grade TlBr 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.

  2. 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.

  3. Radiation hardness of optoelectronic components for the optical readout of the ATLAS inner detector

    NASA Astrophysics Data System (ADS)

    Hou, S.; Ishii, K.; Itoh, M.; Sakemi, Y.; Su, D. S.; Su, T. T.; Teng, P. K.; Yoshida, H. P.

    2011-04-01

    Optical links are used for data transmission of the ATLAS inner detector in a radiation hazard environment at the Large Hadron Collider (LHC). The radiation tolerance is studied for the opto-electronics of GaAs VCSEL and epitaxial Si PIN with 30 and 70 MeV protons at CYRIC. High speed Si and GaAs PIN photo-diodes are also investigated for upgrade to super-LHC. The annealing of GaAs VCSEL by charge injection is characterized. The GaAs devices show approximately linear degradations to fluence. The dependence on proton energy is compared to the Non-Ionizing Energy Loss calculations.

  4. Effects of high energy radiation on the mechanical properties of epoxy graphite fiber reinforced composites

    NASA Technical Reports Server (NTRS)

    Gilbert, R. D.; Fornes, R. E.; Memory, J. D.

    1983-01-01

    The effects of high energy radiation on mechanical properties and on the molecular and structural properties of graphite fiber reinforced composites are assessed so that durability in space applications can be predicted. A listing of composite systems irradiated along with the maximum radiation dose applied and type of mechanical tests performed is shown. These samples were exposed to 1/2 MeV electrons.

  5. Cosmic radiation dose in aircraft--a neutron track etch detector.

    PubMed

    Vuković, B; Radolić, V; Miklavcić, I; Poje, M; Varga, M; Planinić, J

    2007-01-01

    Cosmic radiation bombards us at high altitude by ionizing particles. The radiation environment is a complex mixture of charged particles of solar and galactic origin, as well as of secondary particles produced in interaction of the galactic cosmic particles with the nuclei of atmosphere of the Earth. The radiation field at aircraft altitude consists of different types of particles, mainly photons, electrons, positrons and neutrons, with a large energy range. The non-neutron component of cosmic radiation dose aboard ATR 42 and A 320 aircrafts (flight level of 8 and 11 km, respectively) was measured with TLD-100 (LiF:Mg,Ti) detectors and the Mini 6100 semiconductor dosimeter. The estimated occupational effective dose for the aircraft crew (A 320) working 500 h per year was 1.64 mSv. Other experiments, or dose rate measurements with the neutron dosimeter, consisting of LR-115 track detector and boron foil BN-1 or 10B converter, were performed on five intercontinental flights. Comparison of the dose rates of the non-neutron component (low LET) and the neutron one (high LET) of the radiation field at the aircraft flight level showed that the neutron component carried about 50% of the total dose. The dose rate measurements on the flights from the Middle Europe to the South and Middle America, then to Korea and Japan, showed that the flights over or near the equator region carried less dose rate; this was in accordance with the known geomagnetic latitude effect.

  6. 3D Finite Element Model for Writing Long-Period Fiber Gratings by CO2 Laser Radiation

    PubMed Central

    Coelho, João M. P.; Nespereira, Marta; Abreu, Manuel; Rebordão, José

    2013-01-01

    In the last years, mid-infrared radiation emitted by CO2 lasers has become increasing popular as a tool in the development of long-period fiber gratings. However, although the development and characterization of the resulting sensing devices have progressed quickly, further research is still necessary to consolidate functional models, especially regarding the interaction between laser radiation and the fiber's material. In this paper, a 3D finite element model is presented to simulate the interaction between laser radiation and an optical fiber and to determine the resulting refractive index change. Dependence with temperature of the main parameters of the optical fiber materials (with special focus on the absorption of incident laser radiation) is considered, as well as convection and radiation losses. Thermal and residual stress analyses are made for a standard single mode fiber, and experimental results are presented. PMID:23941908

  7. 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.

  8. Performance characteristics and radiation damage results from the Fermilab E706 silicon microstrip detector system

    NASA Astrophysics Data System (ADS)

    Engels, E.; Mani, S.; Orris, D.; Shepard, P. F.; Weerasundara, P. D.; Choudhary, B. C.; Joshi, U.; Kapoor, V.; Shivpuri, R.; Baker, W.; Berg, D.; Carey, D.; Johnstone, C.; Nelson, C.; Bromberg, C.; Brown, D.; Huston, J.; Miller, R.; Nguyen, A.; Benson, R.; Lukens, P.; Ruddick, K.; Alverson, G.; Faissler, W.; Garelick, D.; Glaubman, M.; Kourbanis, I.; Lirakis, C.; Pothier, E.; Sinanidis, A.; Wu, G.-H.; Yasuda, T.; Yosef, C.; Easo, S.; Hartman, K.; Oh, B. Y.; Toothacker, W.; Whitmore, J.; Ballocchi, G.; Debarbaro, L.; Desoi, W.; Fanourakis, G.; Ferbel, T.; Ginther, G.; Gutierrez, P.; Lanaro, A.; Lobkowicz, F.; Mansour, J.; Pedeville, G.; Prebys, E.; Skow, D.; Slattery, P.; Varelas, N.; Zielinski, M.

    1989-07-01

    A charged particle spectrometer containing a 7120-channel silicon microstrip detector system, one component of Fermilab experiment E706 to study direct photon production in hadron-hadron collisions, was utilized in a run in which 6 million events were recorded. We describe the silicon system, provide early results of track and vertex reconstruction, and present data on the radiation damage to the silicon wafers resulting from the narrow high intensity beam.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    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 241Am-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.

  10. Measurement of Cerenkov radiation induced by the gamma-rays of Co-60 therapy units using wavelength shifting fiber.

    PubMed

    Jang, Kyoung Won; Shin, Sang Hun; Kim, Seon Geun; Kim, Jae Seok; Yoo, Wook Jae; Ji, Young Hoon; Lee, Bongsoo

    2014-04-21

    In this study, a wavelength shifting fiber that shifts ultra-violet and blue light to green light was employed as a sensor probe of a fiber-optic Cerenkov radiation sensor. In order to characterize Cerenkov radiation generated in the developed wavelength shifting fiber and a plastic optical fiber, spectra and intensities of Cerenkov radiation were measured with a spectrometer. The spectral peaks of light outputs from the wavelength shifting fiber and the plastic optical fiber were measured at wavelengths of 500 and 510 nm, respectively, and the intensity of transmitted light output of the wavelength shifting fiber was 22.2 times higher than that of the plastic optical fiber. Also, electron fluxes and total energy depositions of gamma-ray beams generated from a Co-60 therapy unit were calculated according to water depths using the Monte Carlo N-particle transport code. The relationship between the fluxes of electrons over the Cerenkov threshold energy and the energy depositions of gamma-ray beams from the Co-60 unit is a near-identity function. Finally, percentage depth doses for the gamma-ray beams were obtained using the fiber-optic Cerenkov radiation sensor, and the results were compared with those obtained by an ionization chamber. The average dose difference between the results of the fiber-optic Cerenkov radiation sensor and those of the ionization chamber was about 2.09%.

  11. Measurement of Cerenkov Radiation Induced by the Gamma-Rays of Co-60 Therapy Units Using Wavelength Shifting Fiber

    PubMed Central

    Jang, Kyoung Won; Shin, Sang Hun; Kim, Seon Geun; Kim, Jae Seok; Yoo, Wook Jae; Ji, Young Hoon; Lee, Bongsoo

    2014-01-01

    In this study, a wavelength shifting fiber that shifts ultra-violet and blue light to green light was employed as a sensor probe of a fiber-optic Cerenkov radiation sensor. In order to characterize Cerenkov radiation generated in the developed wavelength shifting fiber and a plastic optical fiber, spectra and intensities of Cerenkov radiation were measured with a spectrometer. The spectral peaks of light outputs from the wavelength shifting fiber and the plastic optical fiber were measured at wavelengths of 500 and 510 nm, respectively, and the intensity of transmitted light output of the wavelength shifting fiber was 22.2 times higher than that of the plastic optical fiber. Also, electron fluxes and total energy depositions of gamma-ray beams generated from a Co-60 therapy unit were calculated according to water depths using the Monte Carlo N-particle transport code. The relationship between the fluxes of electrons over the Cerenkov threshold energy and the energy depositions of gamma-ray beams from the Co-60 unit is a near-identity function. Finally, percentage depth doses for the gamma-ray beams were obtained using the fiber-optic Cerenkov radiation sensor, and the results were compared with those obtained by an ionization chamber. The average dose difference between the results of the fiber-optic Cerenkov radiation sensor and those of the ionization chamber was about 2.09%. PMID:24755521

  12. 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.

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

    SciTech Connect

    Franc, J.; Dědič, 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.

  14. 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.

  15. RADIATION-RESISTANT FIBER OPTIC STRAIN SENSORS FOR SNS TARGET INSTRUMENTATION

    SciTech Connect

    Blokland, Willem; Bryan, Jeff; Riemer, Bernie; Sangrey, Robert L; Wendel, Mark W; Liu, Yun

    2016-01-01

    Measurement of stresses and strains in the mercury tar-get vessel of the Spallation Neutron Source (SNS) is important to understand the structural dynamics of the target. This work reports the development of radiation-resistant fiber optic strain sensors for the SNS target in-strumentation.

  16. Electron beam diagnostics tool based on Cherenkov radiation in optical fibers

    NASA Astrophysics Data System (ADS)

    Vukolov, A. V.; Novokshonov, A. I.; Potylitsyn, A. P.; Uglov, S. R.

    2016-07-01

    The results of experimental investigations of Cherenkov radiation in optical fibers with 0.6 mm thickness which were used to scan an electron beam of 5.7 MeV energy are presented. Using such a technique for beam profile measurements it is possible to create a compact and reliable device compared to existing systems based on ionization chambers.

  17. Effects of high energy radiation on the mechanical properties of epoxy/graphite fiber reinforced composites

    NASA Technical Reports Server (NTRS)

    Fornes, R. E.; Gilbert, R. D.; Memory, J. D.

    1987-01-01

    Publications and theses generated on composite research are listed. Surface energy changes of an epoxy based on tetraglycidyl diaminodiphenyl methane (TGDDM)/diaminodiphenyl sulfone (DDS), T-300 graphite fiber and T-300/5208 (graphite fiber/epoxy) composites were investigated after irradiation with 0.5 MeV electrons. Electron spin resonance (ESR) investigations of line shapes and the radical decay behavior were made of an epoxy based on tetraglycidyl diaminodiphenyl methane (TGDDM)/diaminodiphenyl sulfone (DDS), T-300 graphite fiber, and T-300/5208 (graphite fiber/epoxy) composites after irradiation with Co(60) gamma-radiation or 0.5 MeV electrons. The results of the experiments are discussed.

  18. Radiation-resistant erbium-doped optical fiber for space applications

    NASA Astrophysics Data System (ADS)

    Thomas, Jérémie; Myara, Mikha"l.; Signoret, Philippe; Pastouret, Alain; Burov, Ekaterina; Boivin, David; Cavani, Olivier; Sotom, Michel; Maignan, Michel; Gilard, Olivier

    2012-01-01

    In the last decade, there has been increased interest in photonic technology for new satellite applications. One critical issue is the high sensitivity to radiative environments of the Erbium Doped Fiber (EDF). It leads to a radiation-induced absorption (RIA) that is not due to erbium content but mainly to the aluminium that ensures the erbium inclusion in glass. As the radiation induced losses grow as an exponential function of fiber length, the principal way so far to reduce EDFA degradation has consisted in increasing erbium concentration using conventional doping techniques. However, this is limited by the quenching effect, which impacts the fiber length needed to reach high gain, but also by the Aluminium-induced RIA. It has been recently proposed an original nanoparticle (NP) doping approach, which allows codopant content decrease with reduced quenching impact, while keeping EDF amplifying performances. A radiation-resistant amplifier can thus be designed as a "quenching-free", heavily-erbium-doped amplifier with low RIA. We demonstrate for the first time an aluminium-free EDF, exhibiting low quenching and low RIA. Despite the lack of aluminium, using silica NPs allows an erbium concentration close to the one of standard EDFs (200 ppm). This fiber is compared to a 1400 ppm Erbium-doped optical fiber with a strong aluminium concentration. Whereas the two fibers exhibit similar initial optical gain (15 dB under saturation conditions), the NP doped Al-free EDF shows only 2 dB gain reduction after a 600 Gy gamma deposit, while the Al/Er EDF incurs more than 10 dB gain degradation.

  19. 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

  20. Lessons learned from the Radiation measurements of the Mars Science Lab Radiation Assessment Detector (MSL-RAD)

    NASA Astrophysics Data System (ADS)

    Reitz, Guenther; Ottolenghi, Andrea

    2016-07-01

    The Radiation Assessment Detector (RAD) was designed to characterize the radiation environment on the Mars surface and to contribute to an improved assessment of radiation risk for a future human mission to Mars. The flight was chosen to cover a period of solar maximum activity to allow besides the measurement of the galactic cosmic rays an intense study of exposures by solar particle events. The Mars Science Laboratory spacecraft (MSL), containing the Curiosity rover, in which RAD was integrated, was launched to Mars on November 26, 2011. Although not part of the mission planning, RAD was operated already during the 253 day and 560 million km cruise to Mars and made the first time detailed measurements of a radiation environment comparable to that inside a future spacecraft carrying humans to Mars and in other deep space missions. Exactly 100 years after the discovery of cosmic rays on August 7, 1912 RAD makes the first observation of the radiation environment on the surface of another planet and is still gathering data until today. Meanwhile the maximum activity of the current solar cycle has been passed and the solar activity is decreasing. Unfortunately the present solar cycle was an unexpected weak cycle. As a matter of fact only very small solar particle events could be observed during the still ongoing RAD measurements. The paper highlights the achievements of RAD by presenting selected data measured during the cruise and on the Mars surface and describes its impact on predictive models for health risks of astronauts during space missions.

  1. Highly precise stabilization of intracavity prism-based Er:fiber frequency comb using optical-microwave phase detector.

    PubMed

    Zhang, Shuangyou; Wu, Jiutao; Leng, Jianxiao; Lai, Shunnan; Zhao, Jianye

    2014-11-15

    In this Letter, we demonstrate a fully stabilized Er:fiber frequency comb by using a fiber-based, high-precision optical-microwave phase detector. To achieve high-precision and long-term phase locking of the repetition rate to a microwave reference, frequency control techniques (tuning pump power and cavity length) are combined together as its feedback. Since the pump power has been used for stabilization of the repetition rate, we introduce a pair of intracavity prisms as a regulator for carrier-envelope offset frequency, thereby phase locking one mode of the comb to the rubidium saturated absorption transition line. The stabilized comb performs the same high stability as the reference for the repetition rate and provides a residual frequency instability of 3.6×10(-13) for each comb mode. The demonstrated stabilization scheme could provide a high-precision comb for optical communication, direct frequency comb spectroscopy.

  2. Effect of Solar Radiation on Fiber Optic Cables Used in Distributed Temperature Sensing (DTS) Applications

    NASA Astrophysics Data System (ADS)

    Neilson, B. T.; Hatch, C. E.; Bingham, Q. G.; Tyler, S. W.

    2008-12-01

    In recent years, distributed temperature sensing (DTS) has enjoyed steady increases in the number and diversity of applications. Because fiber optic cables used for DTS are typically sheathed in dark materials resistant to UV deterioration, the question arises of how shortwave solar radiation penetrating a water column influences the accuracy of absolute DTS-derived temperatures. Initial calculations of these affects considered: shortwave radiation as a function of time of day, water depth, and water clarity; fiber optic cable dimensions; and fluid velocity. These indicate that for clear waterbodies with low velocities and shallow depths, some heating on the cable is likely during peak daily solar radiation. Given higher water velocities, substantial increases in turbidity, and/or deeper water, there should be negligible solar heating on the cable. To confirm these calculations, a field study was conducted to test the effects of solar radiation by installing two types of fiber optic cable at multiple, uniform depths in a trapezoidal canal with constant flow determined by a controlled release from Porcupine Dam near Paradise, Utah. Cables were installed in water depths from 0.05 to 0.79 m in locations of faster (center of canal) and slower (sidewall) water velocities. Thermister strings were installed at the same depths, but shielded from solar radiation and designed to record absolute water temperatures. Calculations predict that at peak solar radiation, in combination with shallow depths and slow velocities, typical fiber-optic cable is likely to experience heating greater than the ambient water column. In this study, DTS data show differences of 0.1-0.2°C in temperatures as seen by cables separated vertically by 0.31 m on the sidewall and center of the channel. Corresponding thermister data showed smaller vertical differences (~0.03-0.1°C) suggesting thermal stratification was also present in the canal. However, the magnitude of the DTS differences could not be

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

    SciTech Connect

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

    2013-07-15

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

  4. W-band OFDM Radio-over-Fiber system with power detector for vector signal down-conversion.

    PubMed

    Lin, Chun-Ting; Wu, Meng-Fan; Ho, Chun-Hung; Li, Che-Hao; Lin, Chi-Hsiang; Huang, Hou-Tzu

    2015-06-01

    This Letter proposes a W-band OFDM RoF system at 103.5 GHz employing power detector to support vector signal down-conversion. Additional RF tone is generated and transmitted from central office to replace the local oscillator at a wireless receiver. With a proper frequency gap and power ratio between the RF tone and the OFDM-modulated signal, the impact from signal-to-signal beating interference can be minimized. The data rate can achieve a 40 Gbps 16 QAM OFDM signal over 25 km fiber and 2 m wireless transmission. PMID:26030536

  5. 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

  6. New BNL 3D-Trench electrode Si detectors for radiation hard detectors for sLHC and for X-ray applications

    NASA Astrophysics Data System (ADS)

    Li, Zheng

    2011-12-01

    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

  7. Hilbert Spectral Analysis of THz Radiation Sources by High-Tc Josephson Detectors

    NASA Astrophysics Data System (ADS)

    Divin, Yuriy; Lyatti, Matvey; Poppe, Ulrich

    A Hilbert spectrum analyzer was developed and characterized with monochromatic radiation sources at the frequency range from 30 GHz to 1 THz. The analyzer was based on a high-Tc frequency-selective Josephson detector and cooled to temperatures of 60-80K by a Stirling cryocooler. The instrumental function of the spectrum analyzer was shown to be of Lorentz type and within accuracy up to 0.1% without any harmonic and subharmonic contributions. Spectral characterization of THz sources, based on frequency multiplication of input microwave radiation by Schottky diodes, was demonstrated for input frequencies from 10 to 20 GHz with a total scanning time as low as 50 ms per scan. The developed Hilbert spectrum analyzer might be considered as a compact and high-speed substitute of conventional Fourier spectrometers, which are used for characterization of THz radiation sources in combination with liquid-helium-cooled silicon bolometers.

  8. Scattered radiation in flat-detector based cone-beam CT: analysis of voxelized patient simulations

    NASA Astrophysics Data System (ADS)

    Wiegert, Jens; Bertram, Matthias

    2006-03-01

    This paper presents a systematic assessment of scattered radiation in flat-detector based cone-beam CT. The analysis is based on simulated scatter projections of voxelized CT images of different body regions allowing to accurately quantify scattered radiation of realistic and clinically relevant patient geometries. Using analytically computed primary projection data of high spatial resolution in combination with Monte-Carlo simulated scattered radiation, practically noise-free reference data sets are computed with and without inclusion of scatter. The impact of scatter is studied both in the projection data and in the reconstructed volume for the head, thorax, and pelvis regions. Currently available anti-scatter grid geometries do not sufficiently compensate scatter induced cupping and streak artifacts, requiring additional software-based scatter correction. The required accuracy of scatter compensation approaches increases with increasing patient size.

  9. Nuclear reactor pulse tracing using a CdZnTe electro-optic radiation detector

    NASA Astrophysics Data System (ADS)

    Nelson, Kyle A.; Geuther, Jeffrey A.; Neihart, James L.; Riedel, Todd A.; Rojeski, Ronald A.; Ugorowski, Philip B.; McGregor, Douglas S.

    2012-07-01

    CdZnTe has previously been shown to operate as an electro-optic radiation detector by utilizing the Pockels effect to measure steady-state nuclear reactor power levels. In the present work, the detector response to reactor power excursion experiments was investigated. Peak power levels during an excursion were predicted to be between 965 MW and 1009 MW using the Fuchs-Nordheim and Fuchs-Hansen models and confirmed with experimental data from the Kansas State University TRIGA Mark II nuclear reactor. The experimental arrangement of the Pockels cell detector includes collimated laser light passing through a transparent birefringent crystal, located between crossed polarizers, and focused upon a photodiode. The birefringent crystal, CdZnTe in this case, is placed in a neutron beam emanating from a nuclear reactor beam port. After obtaining the voltage-dependent Pockels characteristic response curve with a photodiode, neutron measurements were conducted from reactor pulses with the Pockels cell set at the 1/4 and 3/4 wave bias voltages. The detector responses to nuclear reactor pulses were recorded in real-time using data logging electronics, each showing a sharp increase in photodiode current for the 1/4 wave bias, and a sharp decrease in photodiode current for the 3/4 wave bias. The polarizers were readjusted to equal angles in which the maximum light transmission occurred at 0 V bias, thereby, inverting the detector response to reactor pulses. A high sample rate oscilloscope was also used to more accurately measure the FWHM of the pulse from the electro-optic detector, 64 ms, and is compared to the experimentally obtained FWHM of 16.0 ms obtained with the 10B-lined counter.

  10. TU-F-BRE-01: A High Resolution Micro Fiber Scintillator Detector Optimized for SRS and SBRT in Vivo Real Time Treatment Verification

    SciTech Connect

    Izaguirre, E; Rangaraj, D; Price, S; Knewtson, T; Loyalka, S

    2014-06-15

    Purpose: We have built a high resolution real time scintillating fiber detector prototype to determine in real time the accuracy of stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT) treatments when only a fraction of the planned dose was delivered. The motivation of this work is to enhance dose delivery accuracy and to achieve error free radiosurgery. Methods: A high density array of scintillating fibers and a high speed photo detectors array were integrated to implement a high resolution real time dosimeter that can sample with high resolution pulsed SRS and SBRT beams cross sections. The high efficiency of the developed system allows to read each linac pulse in real time and to compute the accumulated dose and dose errors when only a fraction of the beam was delivered. The fibers are highly packed in a substrate that is directly coupled to two 128 pixel arrays with a pitch matching the fiber spacing to achieve accurate spatial localization. The small cross section of the fiber array allows stacking multiple fiber arrays to measure independent angular profiles that are digitally processed in parallel for real time dosimetry. Results: We implemented a high density array detector prototype with a pitch of 0.5 mm, readout speed of 1.2 msec, and a response time of 0.5 usec. The fast reading speed has the capability to determining the dose in flattening free filter beams. The detector can be installed in transmission mode at the output port of a micro-MLC. Treatment deviations smaller than 3% are detected when less than 1/100 of the planned dose was delivered. Conclusions: We built a prototype of a high resolution fiber scintillator array detector for SRS and SBRT in vivo dosimetry. Results show that the developed detector has the potential to assure error free SRS and SBRT treatments.

  11. The iQID Camera: An Ionizing-Radiation Quantum Imaging Detector

    DOE PAGESBeta

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

    2014-06-11

    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 andmore » 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. In conclusion, we present the latest results and discuss potential applications.« less

  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

    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. In conclusion, we present the latest results and discuss potential applications.

  13. 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.

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

    DOEpatents

    Hermes, Robert E.

    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.

  15. 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.

  16. 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.

  17. CMS Run-2 Instrumentation for beam radiation and luminosity measurement using novel detector technologies

    NASA Astrophysics Data System (ADS)

    Gomez Espinosa, Alejandro; CMS Collaboration Collaboration

    2016-03-01

    The higher energy and luminosity for Run 2 at the LHC initiated the development of dedicated technologies for beam radiation monitoring and luminosity measurement. A dedicated pixel luminosity detector measures coincidences in several three layer telescopes of silicon pixel detectors to arrive at a luminosity for each colliding LHC bunch pair. The full pixel data is also read out at a lower rate to reconstruct charged particle tracks for monitoring and beam spot determination. The upgraded fast beam conditions monitor measures the particle flux using 24 two pad single crystalline diamond sensors, equipped with a fast front-end ASIC, produced in 130 nm CMOS technology, for excellent time resolution. A new beam-halo monitor exploits Cerenkov light production in fused quartz crystals to provide direction sensitivity and excellent time resolution to separate incoming and outgoing particles. The back-end electronics of the beam monitoring systems include dedicated modules with high bandwidth digitizers developed in both VME and microTCA standards for per bunch beam measurements and gain monitoring. All sub-detectors have been taking data from the first day of LHC operation in April 2015. Detector performance results from the 2015 LHC Run II will be presented.

  18. Atmospheric measurements by Medipix-2 and Timepix Ionizing Radiation Imaging Detectors on BEXUS stratospheric balloon campaigns

    NASA Astrophysics Data System (ADS)

    Urbar, Jaroslav; Scheirich, Jan; Jakubek, Jan

    2010-05-01

    Results of the first two experiments using semiconductor pixel detectors of the Medipix family for cosmic ray imaging in the stratospheric environment are presented. The original detecting device was based on the hybrid pixel detectors of Medipix-2 and Timepix developed at CERN with USB interface developed at Institute of Experimental and Applied Physics of Czech Technical University in Prague. The detectors were used in tracking mode allowing them to operate as an "active nuclear emulsion". The actual flight time of BEXUS7 with Medipix-2 on 8th October 2008 was over 4 hours, with 2 hours at stable floating altitude of 26km. BEXUS9 measurements of similar duration by Timepix, Medipix-2 and ST-6 Geiger telescope instruments took place in arctic atmosphere below 24km altitude on 11th October 2009. This balloon platform is quite ideal for such in-situ measurements. Not only because of the high altitudes reached, but also due to its slow ascent velocity for statistically relevant sampling of the ambient environment for improving cosmic ray induced ionisation rate model inputs. The flight opportunity for BEXUS student projects was provided by Education department of the European Space Agency (ESA) and Eurolaunch - Collaboration of Swedish National Space Board (SNSB) and German Space Agency (DLR). The scientific goal was to check energetic particle type altitudinal dependencies, also testing proper detector calibration by detecting fluxes of ionizing radiation, while evaluating instrumentation endurance and performance.

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

    NASA Astrophysics Data System (ADS)

    Banaś, ElŻbieta; 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.

  20. Generation of broadband mid-infrared supercontinuum radiation in cascaded soft-glass fibers

    NASA Astrophysics Data System (ADS)

    Kneis, C.; Robin, T.; Cadier, B.; Brilland, Laurent; Caillaud, Celine; Troles, Johann; Manek-Hönninger, I.; Eichhorn, M.; Kieleck, C.

    2016-03-01

    The generation of mid-infrared (mid-IR) radiation, ranging from 2 - 5 μm, is getting much attention in recent years thanks to many applications it can be used for, e.g. in free space optical communication, range finding, counter measures and remote chemical sensing systems. It also plays an increasing role in medicine, for instance in optical tissue ablation or optical coherence tomography, owing to the high water absorption in that wavelength range. In this research study, a ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) fluoride fiber is pumped by a Q-switched mode-locked (QML) thulium (Tm3+)- doped double-clad silica fiber laser, emitting at around 2 μm, to generate mid-IR supercontinuum (SC). Further spectral broadening of this SC radiation is achieved by coupling it into a chalcogenide arsenide-selenide (AsSe) photonic crystal fiber (PCF). An output power of 24 W at 2 μm has been achieved in QML operation for the Tm3+-doped fiber laser. The SC output power from the ZBLAN fiber has been 7.8 W with a spectrum extending to approximately 4.1 μm. For further wavelength broadening experiments, a long-wave-pass filter with a 3 dB edge around 3.6 μm has been implemented between the ZBLAN and the AsSe fiber to cut out the residual pump light at 2 μm and the radiation between 2 μm and 3.5 μm. The pump power was approximately 120 mW with a spectrum from 3.5 μm to 3.9 μm. First proof of principal experiments has been performed with 20 mW of averaged output power and a spectrum extending to 4.9 μm. The coupling efficiency of the SC radiation from the ZBLAN fiber into the AsSe fiber has been around 30%.

  1. 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

  2. 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

  3. Improving spatial resolution of high stopping power X- and gamma-ray cameras:. fibers or slat-structured detectors?

    NASA Astrophysics Data System (ADS)

    Gerstenmayer, J.-L.

    2000-11-01

    spread on the resolution. Technologies such as scintillator arrays (bundles), photoconductor plate piling, multi-hole- and multi-slat-solid detectors into gas chamber are employed. The first experimental results obtained at CEA are encouraging for applications such as high-energy low-dose fast imaging, flash radiography, radiotherapy positioning, nuclear waste or fuel survey, and, may be, high angular resolution imaging in the field of high-energy astrophysics. The relevance of "future" solutions is then examined, exhibiting theoretical and experimental frontiers: the most efficient structure for a future high-performance 2D integrating imager shall be a piling of thin metal layers, able to boost the quantum efficiency, sandwiched between a few hundreds of micrometers sensitive detectors as low-dark-current photoconductor (micro-strips) or parallel high-performance scintillating fiber sheets.

  4. Fiber optic thermal/fast neutron and gamma ray scintillation detector

    DOEpatents

    Neal, John S.; Mihalczo, John T

    2007-10-30

    A system for detecting fissile and fissionable material originating external to the system includes: a .sup.6Li loaded glass fiber scintillator for detecting thermal neutrons, x-rays and gamma rays; a fast scintillator for detecting fast neutrons, x-rays and gamma rays, the fast scintillator conjoined with the glass fiber scintillator such that the fast scintillator moderates fast neutrons prior to their detection as thermal neutrons by the glass fiber scintillator; and a coincidence detection system for processing the time distributions of arriving signals from the scintillators.

  5. High-performance diamond radiation detectors produced by lift-off method

    NASA Astrophysics Data System (ADS)

    Shimaoka, Takehiro; Kaneko, Junichi H.; Tsubota, Masakatsu; Shimmyo, Hiroaki; Watanabe, Hideyuki; Chayahara, Akiyoshi; Umezawa, Hitoshi; Shikata, Shin-ichi

    2016-03-01

    For stable semiconductor detector operation under harsh environments, an ideal single-crystal diamond without a charge trapping centre is required. For this study, a self-standing single-crystal CVD diamond was fabricated using a lift-off method. The reduction of charge trapping factors such as structural defects, point defects, and nitrogen impurities, was attempted using 0.2% of low-methane concentration growth and using a full metal seal chamber. A high-quality self-standing diamond with strong free-exciton recombination emission was obtained. Charge collection efficiencies were 100.1% for holes and 99.8% for electrons, provided that \\varepsilon{diamond}= 13.1 \\text{eV} and \\varepsilon{Si}=3.62 \\text{eV} . Energy resolutions were 0.38% for both holes and electrons. We produced a high-performance diamond radiation detector using the productive lift-off method.

  6. Measurement of a high electrical quality factor in a niobium resonator for a gravitational radiation detector

    NASA Technical Reports Server (NTRS)

    Folkner, W. M.; Moody, M. V.; Richard, J.-P.

    1989-01-01

    The mechanical and electrical quality factors of a 10-g niobium resonator were measured at 4.4 K and were found to be 8.1 x 10 to the 6th, and 3.8 x 10 to the 6th, respectively. The value for the electrical quality factor is high enough for a system operating at 50 mK at a sensitivity level of one phonon. The resonator's low damping properties make it suitable for use as a transducer for a cryogenic three-mode gravitational radiation detector. A practical design is given for the mounting of the resonator on a 2400-kg aluminum-bar detector. Projections are made for the sensitivity of a 2400-kg bar instrumented as a three-mode system with this resonator inductively coupled to a SQUID.

  7. An HEMT-Based Cryogenic Charge Amplifier for Sub-kelvin Semiconductor Radiation Detectors

    NASA Astrophysics Data System (ADS)

    Phipps, A.; Sadoulet, B.; Juillard, A.; Jin, Y.

    2016-07-01

    We present the design and noise performance of a fully cryogenic (T=4 K) high-electron mobility transistor (HEMT)-based charge amplifier for readout of sub-kelvin semiconductor radiation detectors. The amplifier is being developed for use in direct detection dark matter searches such as the cryogenic dark matter search and will allow these experiments to probe weakly interacting massive particle masses below 10 GeV/c^2 while retaining background discrimination. The amplifier dissipates ≈ 1 mW of power and provides an open loop voltage gain of several hundreds. The measured noise performance is better than that of JFET-based charge amplifiers and is dominated by the noise of the input HEMT. An optimal filter calculation using the measured closed loop noise and typical detector characteristics predicts a charge resolution of σ _q=106 eV (35 electrons) for leakage currents below 4 × 10^{-15} A.

  8. 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.

  9. Influence of solvothermal synthesis conditions in BiSI nanostructures for application in ionizing radiation detectors

    NASA Astrophysics Data System (ADS)

    Aguiar, I.; Mombrú, M.; Pérez Barthaburu, M.; Bentos Pereira, H.; Fornaro, L.

    2016-02-01

    BiSI belongs to the A V B VI C VII chalcohalides group of compounds. These compounds show several interesting properties such as ferroelectricity, piezoelectricity along the c axis, and photoconductivity. Moreover, BiSI is a potential semiconductor material for room-temperature gamma and x-ray detection, given its band gap of 1.57 eV and its high density, 6.41 g cm-3. In this work we present BiSI nanostructures synthesized by the solvothermal method with the intention of using them for ionizing radiation detection. The solvent was varied to study its influence in morphology, particle size and size distribution. Three different conditions were tested, using either water, monoethylene glycol and a mixture of both solvents. Nanostructures were characterized by XRD to determine the phase obtained and reaction completeness; TEM was used to observe nanostructures morphology, size, size distribution and crystallinity; and finally FT-IR diffuse reflectance was used to study monoethylene glycol presence in the samples. Nanorods in the range of 100-200 nm width were obtained in all samples, but round nanoparticles of around 10 nm in diameter were also detected in samples synthesized only with monoethylene glycol. Samples synthesized in monoethylene glycol were used to fabricate pellets to construct detectors. The detectors responded to ionizing radiation and a resistivity in the order of 1013 Ω cm was estimated. This work proposes, to our knowledge, the first study of BiSI for its application in ionizing radiation detection.

  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. SoftWare for Optimization of Radiation Detectors, SWORD Version 5.0.

    SciTech Connect

    STRICKMAN, MARK S.

    2013-10-23

    Version 05 SoftWare for Optimization of Radiation Detectors (SWORD) is a framework to allow easy simulation and evaluation of radiation detection systems. It is targeted at system designers, who want to evaluate and optimize system parameters without actually building hardware first, at sponsors who need to evaluate proposed or actual system designs independent of the supplier, without having access to actual hardware, and at operators who want to use simulation to evaluate observed phenomena. SWORD is vertically integrated and modular. It allows users to define their own radiation detection instruments by building them from basic geometric “objects” and assigning those objects materials, detection, and/or radioactive emission properties. This process is accomplished by a CAD-like graphical user interface, in which objects may be defined, translated, rotated, grouped, arrayed, and/or nested to produce compound objects. In addition to providing the ability to build a detection system model from scratch, SWORD provides a library of “standard” detector design objects that can be used “as is” or modified by the user.

  12. SoftWare for Optimization of Radiation Detectors, SWORD Version 5.0.

    2013-10-23

    Version 05 SoftWare for Optimization of Radiation Detectors (SWORD) is a framework to allow easy simulation and evaluation of radiation detection systems. It is targeted at system designers, who want to evaluate and optimize system parameters without actually building hardware first, at sponsors who need to evaluate proposed or actual system designs independent of the supplier, without having access to actual hardware, and at operators who want to use simulation to evaluate observed phenomena. SWORDmore » is vertically integrated and modular. It allows users to define their own radiation detection instruments by building them from basic geometric “objects” and assigning those objects materials, detection, and/or radioactive emission properties. This process is accomplished by a CAD-like graphical user interface, in which objects may be defined, translated, rotated, grouped, arrayed, and/or nested to produce compound objects. In addition to providing the ability to build a detection system model from scratch, SWORD provides a library of “standard” detector design objects that can be used “as is” or modified by the user.« less

  13. Controllable passive detectors for study of the radiation environment in space and the atmosphere.

    PubMed

    Akopova, A B

    1998-01-01

    We propose to study the radiation environment on board different flight vehicles: cosmos-type satellites, orbital stations, Space Shuttles and civil (sonic and supersonic) aircraft. These investigations will be carried out with single type of passive detector, namely, nuclear photoemulsions (NPE) with adjustable threshold of particle detection within broad range of linear energy transfer (LET) that is done by means of the technique of selective development of NPE exposed in space. These investigations will allow, one to determine: integral spectra of LET of charged particles of cosmic ray (CR) over a wide range from 2.0 to 5 x 10(4) MeV/cm in biological tissue; differential energy spectra of fast neutrons (1-20 MeV); estimation of absorbed and equivalent doses from charged and neutral component CR; charge and energy spectra of low energy nuclei (E < or = 100 MeV) with Z > or = 2 having in view the extreme hazard radiation to biological objects and microelectronic schemes taken on board inside and outside of these different flight vehicles with exposures from several days to several months. The investigation of radiation environment on board the airplanes depending on the flight parameters will be conducted using emulsions of different sensitivity without any controlling of threshold sensitivity (Akopova et al., 1996). The proposed detector can be used in the joint experiments on the new International Cosmic Station "Alpha".

  14. Radiation tolerant fiber Bragg gratings for high temperature monitoring at MGy dose levels.

    PubMed

    Morana, A; Girard, S; Marin, E; Marcandella, C; Paillet, P; Périsse, J; Macé, J-R; Boukenter, A; Cannas, M; Ouerdane, Y

    2014-09-15

    We report a method for fabricating fiber Bragg gratings (FBG) resistant to very severe environments mixing high radiation doses (up to 3 MGy) and high temperatures (up to 230°C). Such FBGs have been written in two types of radiation resistant optical fibers (pure-silica and fluorine-doped cores) by exposures to a 800 nm femtosecond IR laser at power exceeding 500 mW and then subjected to a thermal annealing treatment of 15 min at 750°C. Under radiation, our study reveals that the radiation induced Bragg wavelength shift (BWS) at a 3 MGy dose is strongly reduced compared to responses of FBGs written with nonoptimized conditions. The BWS remains lower than 10 pm for temperatures of irradiation ranging from 25°C to 230°C without noticeable decrease of the FBG peak amplitude. For an applicative point of view, this radiation induced BWS corresponds to an additional error on the temperature measurements lower than 1.5°C, opening the way to the development of radiation-tolerant multi-point temperature sensors for nuclear industry. PMID:26466259

  15. Single-fiber multi-color pyrometry

    DOEpatents

    Small, IV, Ward; Celliers, Peter

    2004-01-27

    This invention is a fiber-based multi-color pyrometry set-up for real-time non-contact temperature and emissivity measurement. The system includes a single optical fiber to collect radiation emitted by a target, a reflective rotating chopper to split the collected radiation into two or more paths while modulating the radiation for lock-in amplification (i.e., phase-sensitive detection), at least two detectors possibly of different spectral bandwidths with or without filters to limit the wavelength regions detected and optics to direct and focus the radiation onto the sensitive areas of the detectors. A computer algorithm is used to calculate the true temperature and emissivity of a target based on blackbody calibrations. The system components are enclosed in a light-tight housing, with provision for the fiber to extend outside to collect the radiation. Radiation emitted by the target is transmitted through the fiber to the reflective chopper, which either allows the radiation to pass straight through or reflects the radiation into one or more separate paths. Each path includes a detector with or without filters and corresponding optics to direct and focus the radiation onto the active area of the detector. The signals are recovered using lock-in amplification. Calibration formulas for the signals obtained using a blackbody of known temperature are used to compute the true temperature and emissivity of the target. The temperature range of the pyrometer system is determined by the spectral characteristics of the optical components.

  16. Single-fiber multi-color pyrometry

    DOEpatents

    Small, IV, Ward; Celliers, Peter

    2000-01-01

    This invention is a fiber-based multi-color pyrometry set-up for real-time non-contact temperature and emissivity measurement. The system includes a single optical fiber to collect radiation emitted by a target, a reflective rotating chopper to split the collected radiation into two or more paths while modulating the radiation for lock-in amplification (i.e., phase-sensitive detection), at least two detectors possibly of different spectral bandwidths with or without filters to limit the wavelength regions detected and optics to direct and focus the radiation onto the sensitive areas of the detectors. A computer algorithm is used to calculate the true temperature and emissivity of a target based on blackbody calibrations. The system components are enclosed in a light-tight housing, with provision for the fiber to extend outside to collect the radiation. Radiation emitted by the target is transmitted through the fiber to the reflective chopper, which either allows the radiation to pass straight through or reflects the radiation into one or more separate paths. Each path includes a detector with or without filters and corresponding optics to direct and focus the radiation onto the active area of the detector. The signals are recovered using lock-in amplification. Calibration formulas for the signals obtained using a blackbody of known temperature are used to compute the true temperature and emissivity of the target. The temperature range of the pyrometer system is determined by the spectral characteristics of the optical components.

  17. Single-fiber multi-color pyrometry

    SciTech Connect

    Small, W. IV; Celliers, P.

    2000-01-11

    This invention is a fiber-based multi-color pyrometry set-up for real-time non-contact temperature and emissivity measurement. The system includes a single optical fiber to collect radiation emitted by a target, a reflective rotating chopper to split the collected radiation into two or more paths while modulating the radiation for lock-in amplification (i.e., phase-sensitive detection), at least two detectors possibly of different spectral bandwidths with or without filters to limit the wavelength regions detected and optics to direct and focus the radiation onto the sensitive areas of the detectors. A computer algorithm is used to calculate the true temperature and emissivity of a target based on blackbody calibrations. The system components are enclosed in a light-tight housing, with provision for the fiber to extend outside to collect the radiation. Radiation emitted by the target is transmitted through the fiber to the reflective chopper, which either allows the radiation to pass straight through or reflects the radiation into one or more separate paths. Each path includes a detector with or without filters and corresponding optics to direct and focus the radiation onto the active area of the detector. The signals are recovered using lock-in amplification. Calibration formulas for the signals obtained using a blackbody of known temperature are used to compute the true temperature and emissivity of the target. The temperature range of the pyrometer system is determined by the spectral characteristics of the optical components.

  18. Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

    SciTech Connect

    Gregory L. Baker; Ruby N. Ghosh; D.J. Osborn; Po Zhang

    2006-06-30

    A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Our approach towards immobilizing the potassium salt of the molybdenum cluster, K{sub 2}Mo{sub 6}Cl{sub 14}, at the far end of an optical fiber is to embed the cluster in a thermally cured sol-gel matrix particle. This particle-in-binder approach affords fibers with greatly improved mechanical properties, as compared to previous approaches. The sensor was characterized in 2-21% gas phase oxygen at 40, 70 and 100 C. These are promising results for a high temperature fiber optical oxygen sensor based on molybdenum chloride clusters.

  19. 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

  20. 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.

  1. 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.

  2. Influence of photo-inscription conditions on the radiation-response of fiber Bragg gratings.

    PubMed

    Morana, Adriana; Girard, Sylvain; Marin, Emmanuel; Lancry, Matthieu; Marcandella, Claude; Paillet, Philippe; Lablonde, Laurent; Robin, Thierry; Williams, Robert J; Withford, Michael J; Boukenter, Aziz; Ouerdane, Youcef

    2015-04-01

    We compared the sensitivity to X-rays of several fiber Bragg gratings (FBGs) written in the standard telecommunication fiber Corning SMF28 with different techniques. Standard gratings were manufactured with phase-mask and UV lasers, continuum wave (cw) at 244 nm or pulsed in the nanosecond domain at 248 nm, in a pre-hydrogenated fiber. Others gratings were written by exposures to a femtosecond IR-laser (800 nm), with both phase-mask and point by point techniques. The response of these FBGs was studied under X-rays at room temperature and 100°C, by highlighting their similarities and differences. Independently of the inscription technique, the two types of fs-FBGs have showed no big difference up to 1 MGy(SiO(2)) dose. A discussion on the causes of the radiation-induced peak change is also reported. PMID:25968704

  3. The role of nanostructures and quantum dots in detectors and solar cells for radiation hardened space applications

    NASA Astrophysics Data System (ADS)

    Taylor, Edward W.

    2006-08-01

    Highly efficient IR detectors and photo-voltaic solar cells that incorporate nanotechnology composed of nanostructures and nanoparticles (including quantum dots) will play an important role in advanced photonic space applications. While the development of Si-based solar cells has successfully evolved into an efficient and economical technology these devices are predicted to soon reach their theoretical 29% limit efficiency. Alternative organic/polymer solar cells and IR detectors incorporating quantum dots and various nanoparticle or nanostructure materials are emerging which are expected to eventually outperform current state-of-the-art detectors and solar cell devices. By tailoring the QD design wavelength-optimized detectors and detector arrays operating over the UV-IR range can be realized. Specific examples for achieving near-IR photovoltaic and photoconductive detectors with high quantum efficiencies are presented along with brief examples of empirical data reported for assessing the radiation resistance of QD nanocrystalline devices for application in space environments.

  4. POLARIZATION STUDIES OF CdZnTe DETECTORS USING SYNCHROTRON X-RAY RADIATION.

    SciTech Connect

    CAMARDA,G.S.; BOLOTNIKOV, A.E.; CUI, Y.; HOSSAIN, A.; JAMES, R.B.

    2007-07-01

    New results on the effects of small-scale defects on the charge-carrier transport in single-crystal CdZnTe (CZT) material were produced. We conducted detailed studies of the role of Te inclusions in CZT by employing a highly collimated synchrotron x-ray radiation source available at Brookhaven's National Synchrotron Light Source (NSLS). We were able to induce polarization effects by irradiating specific areas with the detector. These measurements allowed the first quantitative comparison between areas that are free of Te inclusions and those with a relatively high concentration of inclusions. The results of these polaration studies will be reported.

  5. Nuclear reactor pulse calibration using a CdZnTe electro-optic radiation detector.

    PubMed

    Nelson, Kyle A; Geuther, Jeffrey A; Neihart, James L; Riedel, Todd A; Rojeski, Ronald A; Saddler, Jeffrey L; Schmidt, Aaron J; McGregor, Douglas S

    2012-07-01

    A CdZnTe electro-optic radiation detector was used to calibrate nuclear reactor pulses. The standard configuration of the Pockels cell has collimated light passing through an optically transparent CdZnTe crystal located between crossed polarizers. The transmitted light was focused onto an IR sensitive photodiode. Calibrations of reactor pulses were performed using the CdZnTe Pockels cell by measuring the change in the photodiode current, repeated 10 times for each set of reactor pulses, set between 1.00 and 2.50 dollars in 0.50 increments of reactivity.

  6. 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.

  7. Ultra-low-power radiation hard ADC for particle detector readout applications

    NASA Astrophysics Data System (ADS)

    Mikkola, E. O.; Swaminathan, V.; Sivakumar, B.; Barnaby, H. J.

    2013-04-01

    Radiation hard analog to digital converter (ADC) has been designed for future high energy physics experiments. The ADC has been designed in a commercial 130 nm CMOS process and it achieves 12-bit resolution, 25 MS/s sampling speed, 15 mW power consumption and hardness to at least 1.8 Megarad(Si) of total ionizing dose (TID). 16 ADC channels will be placed on one packaged silicon chip. The readout of the Liquid Argon Calorimeter of the ATLAS detector in the planned High-Luminosity Large Hadron Collider is one possible application for this ADC.

  8. 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.

  9. Development of a wavelength-separated type scintillator with optical fiber (SOF) dosimeter to compensate for the Cerenkov radiation effect.

    PubMed

    Ishikawa, Masayori; Nagase, Naomi; Matsuura, Taeko; Hiratsuka, Junichi; Suzuki, Ryusuke; Miyamoto, Naoki; Sutherland, Kenneth Lee; Fujita, Katsuhisa; Shirato, Hiroki

    2015-03-01

    The scintillator with optical fiber (SOF) dosimeter consists of a miniature scintillator mounted on the tip of an optical fiber. The scintillator of the current SOF dosimeter is a 1-mm diameter hemisphere. For a scintillation dosimeter coupled with an optical fiber, measurement accuracy is influenced by signals due to Cerenkov radiation in the optical fiber. We have implemented a spectral filtering technique for compensating for the Cerenkov radiation effect specifically for our plastic scintillator-based dosimeter, using a wavelength-separated counting method. A dichroic mirror was used for separating input light signals. Individual signal counting was performed for high- and low-wavelength light signals. To confirm the accuracy, measurements with various amounts of Cerenkov radiation were performed by changing the incident direction while keeping the Ir-192 source-to-dosimeter distance constant, resulting in a fluctuation of <5%. Optical fiber bending was also addressed; no bending effect was observed for our wavelength-separated SOF dosimeter.

  10. Development of a wavelength-separated type scintillator with optical fiber (SOF) dosimeter to compensate for the Cerenkov radiation effect

    PubMed Central

    Ishikawa, Masayori; Nagase, Naomi; Matsuura, Taeko; Hiratsuka, Junichi; Suzuki, Ryusuke; Miyamoto, Naoki; Sutherland, Kenneth Lee; Fujita, Katsuhisa; Shirato, Hiroki

    2015-01-01

    The scintillator with optical fiber (SOF) dosimeter consists of a miniature scintillator mounted on the tip of an optical fiber. The scintillator of the current SOF dosimeter is a 1-mm diameter hemisphere. For a scintillation dosimeter coupled with an optical fiber, measurement accuracy is influenced by signals due to Cerenkov radiation in the optical fiber. We have implemented a spectral filtering technique for compensating for the Cerenkov radiation effect specifically for our plastic scintillator-based dosimeter, using a wavelength-separated counting method. A dichroic mirror was used for separating input light signals. Individual signal counting was performed for high- and low-wavelength light signals. To confirm the accuracy, measurements with various amounts of Cerenkov radiation were performed by changing the incident direction while keeping the Ir-192 source-to-dosimeter distance constant, resulting in a fluctuation of <5%. Optical fiber bending was also addressed; no bending effect was observed for our wavelength-separated SOF dosimeter. PMID:25618136

  11. 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.

  12. 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.

  13. Radiation effects on optical frequency domain reflectometry fiber-based sensor.

    PubMed

    Rizzolo, S; Marin, E; Cannas, M; Boukenter, A; Ouerdane, Y; Périsse, J; Macé, J-R; Bauer, S; Marcandella, C; Paillet, P; Girard, S

    2015-10-15

    We investigate the radiation effects on germanosilicate optical fiber acting as the sensing element of optical frequency domain reflectometry devices. Thanks to a new setup permitting to control temperature during irradiation, we evaluate the changes induced by 10 keV x rays on their Rayleigh response up to 1 MGy in a temperature range from -40°C up to 75°C. Irradiation at fixed temperature points out that its measure is reliable during both irradiation and the recovery process. Mixed temperature and radiation measurements show that changing irradiation temperature leads to an error in distributed measurements that depends on the calibration procedure. These results demonstrate that Rayleigh-based optical fiber sensors are very promising for integration in harsh environments. PMID:26469566

  14. Effects of high energy radiation on the mechanical properties of epoxy/graphite fiber composites

    NASA Technical Reports Server (NTRS)

    Fornes, R. E.; Memory, J. D.

    1981-01-01

    Studies on the effects of high energy radiation on graphite fiber reinforced composites are summarized. Studies of T300/5208 and C6000/PMR15 composites, T300 fibers and the resin system MY720/DDS (tetraglycidyl-4,4'-diaminodiphenyl methane cured with diaminodiphenyl sulfone) are included. Radiation dose levels up to 8000 Mrads were obtained with no deleterious effects on the breaking stress or modulus. The effects on the structure and morphology were investigated using mechanical tests, electron spin resonance, X-ray diffraction, and electron spectroscopy for chemical analysis (ESCA or X-ray photoelectron spectroscopy). Details of the experiments and results are given. Studies of the fracture surfaces of irradiated samples were studied with scanning electron microscopy; current results indicate no differences in the morphology of irradiated and control samples.

  15. Design and construction of a large cylindrical transition radiation detector for the VENUS experiment

    NASA Astrophysics Data System (ADS)

    Sakuda, M.; Fukushima, Y.; Hayashi, K.; Kohriki, T.; Nakamura, S.; Ogawa, K.; Watase, Y.; Haba, J.; Kanda, N.; Suzuki, A.; Suzuki, Y.; Tsukamoto, A.; Yamamoto, H.; Chiba, Y.; Ohsugi, T.; Taketani, A.; Terunuma, N.; Nakano, I.

    1992-01-01

    We describe the design considerations and construction techniques of a large cylindrical transition radiation detector (TRD), 296 cm long and 311.4 cm in diameter, for the VENUS experiment at the e+e+ storage ring, TRISTAN. The design is based on measurements by using test chambers with e/π beams and X-ray sources. The test results will be fully described. The TRD contains four modules of radiators, each followed by an X-ray chamber with 8192 (2688) total (sense) wires. The gain calibration of all sense wires has been completed with an accuracy of 5%. The TRD is expected to provide a pion rejection ratio of 15+/-3 with an electron efficiency of 90% for isolated tracks with momenta above 1 GeV/c.

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

    DOEpatents

    Artuso, Joseph F.; Franks, Larry A.; Hull, Kenneth L.; Symko, Orest G.

    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).

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

    PubMed

    Golnik, N; Gryziński, 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.

  18. E-beam-Cure Fabrication of Polymer Fiber/Matrix Composites for Multifunctional Radiation Shielding

    NASA Technical Reports Server (NTRS)

    Wilson, John W.; Jensen, Brian J.; Thibeault, Sheila A.; Hou, Tan-Hung; Saether, Erik; Glaessgen, Edward H.; Humes, Donald H.; Chang, Chie K.; Badavi, Francis F.; Kiefer, Rrichard L.; Adams, Dan O.

    2004-01-01

    Aliphatic polymers were identified as optimum radiation polymeric shielding materials for building multifunctional structural elements. Conceptual damage-tolerant configurations of polyolefins have been proposed but many issues on the manufacture remain. In the present paper, we will investigate fabrication technologies with e-beam curing for inclusion of high-strength aliphatic polymer fibers into a highly cross-linked polyolefin matrix. A second stage of development is the fabrication methods for applying face sheets to aliphatic polymer closed-cell foams.

  19. SNM Movement Detection/Radiation Sensors and Advanced Materials Portfolio Review, CdMnTe (CMT) Gamma Ray Detectors

    SciTech Connect

    Bolotnikov,A.

    2009-06-02

    The project goals are: (1) Develop CMT radiation detectors - Demonstrate feasibility (Phase 1 is complete) and Improve material properties and device performance; (2) This project will lead to novel radiation detectors - high detection efficiency, high energy-resolution, ambient-temperature operation, and low production cost; and (3) Such detectors are needed in areas of nonproliferation and national security for detection of SNM. Research highlights are: (1) We achieved our Phase-I goal - Demonstration of CMT detector performance approaching that of CZT detectors; (2) Demonstrated that In-doped CMT is much closer to its anticipated performance as radiation detectors than other alternative materials, TlBr and HgI{sub 2} - Large crystal volumes, 10{sup 10}{Omega}{center_dot}cm, 3 x 10{sup -3}cm{sup 2}/V, and stable response; and (3) Conducted material and device characterization experiments - Detectors: I-V, {mu}{sub e}, ({mu}{tau}){sub e}, internal E fields, energy spectra, and high-resolution x-ray response mapping data and Materials - DLTS, TCT, PL, EPDs, XRD, PCD and IR transmission.

  20. 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