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1

Radiation detector  

DOEpatents

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.

Fultz, B.T.

1980-12-05

2

Radiation detector  

DOEpatents

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.

Fultz, Brent T. (Berkeley, CA)

1983-01-01

3

Tin Can Radiation Detector.  

ERIC Educational Resources Information Center

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)

Crull, John L.

1986-01-01

4

Underwater radiation detector  

DOEpatents

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.

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

1986-01-01

5

Superlattice electroabsorption radiation detector  

SciTech Connect

This paper provides a preliminary investigation of a new class of superlattice electroabsorption radiation detectors that employ direct optical modulation for high-speed, two-dimensional (2-D), high-resolution imaging. Applications for the detector include nuclear radiation measurements, tactical guidance and detection (laser radar), inertial fusion plasma studies, and satellite-based sensors. Initial calculations discussed in this paper indicate that a 1.5-{mu}m (GaAlAs) multi-quantum-well (MQW) Fabry-Perot detector can respond directly to radiation of energies 1 eV to 10 KeV, and indirectly (with scattering targets) up through gamma, with 2-D sample rates on the order of 20 ps.

Cooke, B.J.

1993-06-01

6

Superlattice electroabsorption radiation detector  

SciTech Connect

This paper provides a preliminary investigation of a new class of superlattice electroabsorption radiation detectors that employ direct optical modulation for high-speed, two-dimensional (2-D), high-resolution imaging. Applications for the detector include nuclear radiation measurements, tactical guidance and detection (laser radar), inertial fusion plasma studies, and satellite-based sensors. Initial calculations discussed in this paper indicate that a 1.5-[mu]m (GaAlAs) multi-quantum-well (MQW) Fabry-Perot detector can respond directly to radiation of energies 1 eV to 10 KeV, and indirectly (with scattering targets) up through gamma, with 2-D sample rates on the order of 20 ps.

Cooke, B.J.

1993-06-01

7

Ionizing radiation detector  

DOEpatents

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.

Thacker, Louis H. (Knoxville, TN)

1990-01-01

8

Amorphous silicon radiation detectors  

DOEpatents

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.

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

1992-01-01

9

Amorphous silicon radiation detectors  

DOEpatents

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.

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

1992-11-17

10

Semiconductor radiation detector  

DOEpatents

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.

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

2002-01-01

11

Precision synchrotron radiation detectors  

SciTech Connect

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.

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

12

Semiconductor radiation detector  

DOEpatents

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

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

2010-03-30

13

Radiation Hazard Detector  

NASA Technical Reports Server (NTRS)

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.

1978-01-01

14

Diamond radiation detectors II. CVD diamond development for radiation detectors  

SciTech Connect

Interest in radiation detectors has supplied some of the impetus for improving the electronic properties of CVD diamond. In the present discussion, we will restrict our attention to polycrystalhne CVD material. We will focus on the evolution of these materials over the past decade and the correlation of detector performance with other properties of the material.

Kania, D.R.

1997-05-16

15

Simple dynamic electromagnetic radiation detector  

NASA Technical Reports Server (NTRS)

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.

Been, J. F.

1972-01-01

16

Portable Radiation Detectors  

NASA Technical Reports Server (NTRS)

Through a Small Business Innovation Research (SBIR) contract from Kennedy Space Center, General Pneumatics Corporation's Western Research Center satisfied a NASA need for a non-clogging Joule-Thomson cryostat to provide very low temperature cooling for various sensors. This NASA-supported cryostat development played a key part in the development of more portable high-purity geranium gamma-ray detectors. Such are necessary to discern between the radionuclides in medical, fuel, weapon, and waste materials. The outcome of the SBIR project is a cryostat that can cool gamma-ray detectors, without vibration, using compressed gas that can be stored compactly and indefinitely in a standby mode. General Pneumatics also produces custom J-T cryostats for other government, commercial and medical applications.

1997-01-01

17

SEMICONDUCTOR NUCLEAR RADIATION DETECTORS  

Microsoft Academic Search

Silicon p-n junction detectors were fabricated by diffusing phosphorus ; to 2 mu depth into high resistivity p-type silicon. Various base material ; resistivities were employed, ranging from 1000 OMEGA -cm to 9600 OMEGA -cm. ; The devices produced have an encapsulated construction which preserves a good ; protection of the junction edge. Devices of 2-mm, 5-mm, and 12.5-mm sensitive

J. Terada; J. Yoshida; Y. Ebara; T. Kobayashi

1963-01-01

18

Advanced Space Radiation Detector Technology Development  

NASA Technical Reports Server (NTRS)

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.

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

2013-01-01

19

Advanced Space Radiation Detector Technology Development  

NASA Technical Reports Server (NTRS)

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.

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

2013-01-01

20

Advanced Space Radiation Detector Technology Development  

NASA Technical Reports Server (NTRS)

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.

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

2013-01-01

21

Flexible composite radiation detector  

DOEpatents

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.

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

2006-12-05

22

Ionizing Radiation Detector  

DOEpatents

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.

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

2003-11-18

23

Radiation detector spectrum simulator  

DOEpatents

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.

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

1985-04-09

24

Direct detector for terahertz radiation  

DOEpatents

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.

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

2008-09-02

25

Electromechanically-cooled germanium radiation detector system.  

National Technical Information Service (NTIS)

We have successfully developed and fielded an electromechanically cooled germanium radiation detector (EMC-HPGe) at Lawrence Livermore National Laboratory (LLNL). This detector system was designed to provide optimum energy resolution, long lifetime, and e...

A. Lavietes

1998-01-01

26

Hybrid anode for semiconductor radiation detectors  

DOEpatents

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).

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

2013-11-19

27

Radiation experience with the CDF silicon detectors  

SciTech Connect

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.

Husemann, Ulrich; /Rochester U.

2005-11-01

28

Radiation Experience witht eh CDF Silicon Detectors.  

National Technical Information Service (NTIS)

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 descr...

U. Husemann

2006-01-01

29

Resonant-mass detectors of gravitational radiation.  

PubMed

A network of second-generation low-temperature gravitational radiation detectors is nearing completion. These detectors, sensitive to mechanical strains of order 10(-18), are possible because of a variety of technical innovations hat have been made in cryogenics, low-noise superconducting instrumentation, and vibration isolation techniques. Another five orders of magnitude improvement in energy sensitivity of resonant-mass detectors is possible before the linear amplifier quantum limit is encountered. PMID:17830923

Michelson, P F; Price, J C; Taber, R C

1987-07-10

30

Active microphonic noise cancellation in radiation detectors  

NASA Astrophysics Data System (ADS)

A new adaptive filtering technique to reduce microphonic noise in radiation detectors is presented. The technique is based on system identification that actively cancels the microphonic noise. A sensor is used to measures mechanical disturbances that cause vibration on the detector assembly, and the digital adaptive filtering estimates the impact of these disturbances on the microphonic noise. The noise then can be subtracted from the actual detector measurement. In this paper the technique is presented and simulations are used to support this approach.

Zimmermann, Sergio

2013-11-01

31

Automated detector of radiation-acoustic signals  

SciTech Connect

This detector of radiation-acoustic signals is built around an IBM compatible computer to the CAMAC standard and is used to study phase states, thermoelastic, and other thermal properties of solids under a beam of ionizing particles. The detector includes a set of transducers, ADC unit, analog switches, and relay and synchronization units.

Kresnin, Yu.A.; Popov, G.F.; Rudychev, D.V.; Stervoedov, N.G. [Khar`kov State Univ. (Ukraine)

1995-03-01

32

Radiation damage in silicon microstrip detectors  

Microsoft Academic Search

A radiation damage effect on silicon strip detectors of pn-junction type is investigated using a high energy proton beam. In order to clarify the cause of leakage current increase, several variations of strip detectors with different surface structures were made and tested. No appreciable differences in leakage current increase are observed among these samples. A strong temperature dependence on leakage

T. Ohsugi; A. Taketani; M. Noda; Y. Chiba; M. Asai; T. Kondo; T. Sato; M. Takasaki; K. H. Tanaka; K. Kondo; H. Hirayama; K. Yamamoto; H. Tanaka

1988-01-01

33

Metamaterials for Cherenkov Radiation Based Particle Detectors  

SciTech Connect

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.

Tyukhtin, A. V. [Physical Dep. of St.-Petersburg State University, St.-Petersburg (Russian Federation); Schoessow, P.; Kanareykin, A. [Euclid Techlabs, 1375 Piccard Dr, Rockville, MD 20850 (United States); Antipov, S. [Argonne National Laboratory, 9700 S Cass Ave, Argonne, IL 60439 (United States)

2009-01-22

34

Semiconductor Nuclear Radiation Detector Studies.  

National Technical Information Service (NTIS)

In response to a problem that arose with regard to the availability of germanium for lithium-drifted germanium detectors (Ge(Li) detectors), a comprehensive program was undertaken aimed toward the development of a method for the rapid specification of ger...

A. H. Sher

1974-01-01

35

Enhanced radiation detectors using luminescent materials  

DOEpatents

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.

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

2001-01-01

36

Processing circuitry for single channel radiation detector  

NASA Technical Reports Server (NTRS)

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.

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

2009-01-01

37

Wafer-fused semiconductor radiation detector  

DOEpatents

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.

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

2002-01-01

38

Synchrotron light sources and radiation detector metrology  

NASA Astrophysics Data System (ADS)

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

Owens, Alan

2012-12-01

39

Device for calibrating a radiation detector system  

DOEpatents

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.

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

1994-12-27

40

Device for calibrating a radiation detector system  

DOEpatents

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.

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

1994-01-01

41

Metallisation of single crystal diamond radiation detectors  

NASA Astrophysics Data System (ADS)

Properties such as a large band gap, high thermal conductivity and resistance to radiation damage make diamond an extremely attractive candidate for detectors in next generation particle physics experiments. This paper presents our technique for metallisation of a single crystal diamond grown by chemical vapour deposition (CVD) for use as a radiation detector, suitable for operation in places such as the Large Hadron Collider. The front and back side of the diamond are metalised with aluminium and gold on top of titanium respectively, after which the diamond is mounted and read out via a charge sensitive preamplifier. The device is found to collect charge at an efficiency of 97%.

Ong, Lucas; Ganesan, Kumaravelu; Alves, Andrew; Barberio, Elisabetta

2012-10-01

42

Integrator Circuitry for Single Channel Radiation Detector  

NASA Technical Reports Server (NTRS)

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.

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

2008-01-01

43

Compton scatter transition radiation detectors for ACCESS  

NASA Astrophysics Data System (ADS)

The detection of transition radiation x-rays can provide a direct, non-destructive measurement of a particle's Lorentz factor. Standard transition radiation detectors (TRDs) typically incorporate thin plastic foil radiators and gas-filled x-ray detectors, and are sensitive up to ? ~ 104. To reach higher Lorentz factors (up to ? ~ 105), thicker, denser radiators can be used, which consequently produce x-rays of harder energies (? 100 keV). At these energies, scintillator detectors are more efficient in detecting the hard x-rays, and Compton scattering of the x-rays out of the path of the particle becomes an important effect. The Compton scattering can be utilized to separate the transition radiation from the ionization background spatially. We have designed and built a Compton Scatter TRD optimized for high Lorentz factors and exposed it to the electron beam at the CERN SPS. In this paper, we discuss the design principles for a high energy TRD; present preliminary results of the accelerator tests, demonstrating the effectiveness of the Compton Scatter TRD approach; and finally, discuss the application of this technique to the ACCESS cosmic-ray mission.

Case, Gary L.; Cherry, Michael L.

2004-01-01

44

High resolution amorphous silicon radiation detectors  

DOEpatents

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.

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

1992-05-26

45

High resolution amorphous silicon radiation detectors  

DOEpatents

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.

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

1992-01-01

46

Radiation detectors for occupational safety measurements  

NASA Astrophysics Data System (ADS)

The effective radiant exposures for artificial and natural UV-sources are determined by temporal integration over an 8 h working day. Therefore the spectrally weighted integration of the spectral irradiance from the radiation source in the plane of the exposure is to measure. Such measaurements are made with two different detector systems: measurements of UV radiation according to the integral method should be possible according to a quasi partial filtering method using different individually filtered photodiodes. A spectroradiometer for UV radiation analysis was tested due to its application in field measurements for meteorology, medicin, and occupational safety. The optical part of this compact instrument consists of a cosentrance optic, a monochromator and detector system. A comparison with commercial instruments is described.

Kaase, Heinrich; Chen, Mai; Grothmann, Knut

1995-09-01

47

Amorphous silicon based radiation detectors  

SciTech Connect

We describe the characteristics of thin(1 {mu}m) and thick (>30{mu}m) hydrogenated amorphous silicon p-i-n diodes which are optimized for detecting and recording the spatial distribution of charged particles, x-rays and {gamma} rays. For x-ray, {gamma} ray, and charged particle detection we can use thin p-i-n photosensitive diode arrays coupled to evaporated layers of suitable scintillators. For direct detection of charged particles with high resistance to radiation damage, we use the thick p-i-n diode arrays. 13 refs., 7 figs.

Perez-Mendez, V.; Cho, G.; Drewery, J.; Jing, T.; Kaplan, S.N.; Qureshi, S.; Wildermuth, D. (Lawrence Berkeley Lab., CA (United States)); Fujieda, I.; Street, R.A. (Xerox Palo Alto Research Center, CA (United States))

1991-07-01

48

Application of solid state nuclear track detectors in radiation protection.  

National Technical Information Service (NTIS)

This article reviews the current status of the application of nuclear track detectors with emphasis on recent developments in the field of radiation protection. Track etch detectors have been used for the measurements of low level radiation in the environ...

T. V. Ramachandran M. C. Subba Ramu U. C. Mishra

1989-01-01

49

The Radiation Assessment Detector (RAD) Investigation  

NASA Astrophysics Data System (ADS)

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.

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

50

Electromechanically-cooled germanium radiation detector system  

SciTech Connect

We have successfully developed and fielded an electromechanically cooled germanium radiation detector (EMC-HPGe) at Lawrence Livermore National Laboratory (LLNL). This detector system was designed to provide optimum energy resolution, long lifetime, and extremely reliable operation for unattended and portable applications. For most analytical applications, high-purity germanium (HPGe) detectors are the standard detectors of choice, providing an unsurpassed combination of high energy resolution performance and exceptional detection efficiency. Logistical difficulties associated with providing the required liquid nitrogen (LN) for cooling is the primary reason that these systems are found mainly in laboratories. The EMC-HPGe detector system described in this paper successfully provides HPGe detector performance in a portable instrument that allows for isotopic analysis in the field. It incorporates a unique active vibration control system that allows the use of a Sunpower Stirling cycle cryocooler unit without significant spectral degradation from microphonics. All standard isotopic analysis codes, including MGA and MGA++[1], GAMANL[2], GRPANL[3] and MGAU[4], typically used with HPGe detectors can be used with this system with excellent results. Several national and international Safeguards organizations including the International Atomic Energy Agency (IAEA) and U.S. Department of Energy (DOE) have expressed interest in this system. The detector was combined with custom software and demonstrated as a rapid Field Radiometric Identification System (FRIS) for the U.S. Customs Service[5]. The European Communities' Safeguards Directorate (EURATOM) is field-testing the first Safeguards prototype in their applications. The EMC-HPGe detector system design, recent applications, and results will be highlighted.

Lavietes, A. D., LLNL.

1998-05-01

51

Electromechanically cooled germanium radiation detector system  

NASA Astrophysics Data System (ADS)

We have successfully developed and fielded an electromechanically cooled germanium radiation detector (EMC-HPGe) at Lawrence Livermore National Laboratory (LLNL). This detector system was designed to provide optimum energy resolution, long lifetime, and extremely reliable operation for unattended and portable applications. For most analytical applications, high purity germanium (HPGe) detectors are the standard detectors of choice, providing an unsurpassed combination of high energy resolution performance and exceptional detection efficiency. Logistical difficulties associated with providing the required liquid nitrogen (LN) for cooling is the primary reason that these systems are found mainly in laboratories. The EMC-HPGe detector system described in this paper successfully provides HPGe detector performance in a portable instrument that allows for isotopic analysis in the field. It incorporates a unique active vibration control system that allows the use of a Sunpower Stirling cycle cryocooler unit without significant spectral degradation from microphonics. All standard isotopic analysis codes, including MGA and MGA++ [1], GAMANL [2], GRPANL [3]and MGAU [4], typically used with HPGe detectors can be used with this system with excellent results. Several national and international Safeguards organisations including the International Atomic Energy Agency (IAEA) and U.S. Department of Energy (DOE) have expressed interest in this system. The detector was combined with custom software and demonstrated as a rapid Field Radiometric Identification System (FRIS) for the U.S. Customs Service [5]. The European Communities' Safeguards Directorate (EURATOM) is field-testing the first Safeguards prototype in their applications. The EMC-HPGe detector system design, recent applications, and results will be highlighted.

Lavietes, Anthony D.; Joseph Mauger, G.; Anderson, Eric H.

1999-02-01

52

Alpha-beta radiation detector  

DOEpatents

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.

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

1998-08-18

53

Alpha-beta radiation detector  

DOEpatents

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.

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

1998-01-01

54

Miniature detector measures deep space radiation  

NASA Astrophysics Data System (ADS)

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)

Schultz, Colin

2011-08-01

55

Dose response of various radiation detectors to synchrotron radiation  

NASA Astrophysics Data System (ADS)

Accurate dosimetry is particularly difficult for low- to medium-energy x-rays as various interaction processes with different dependences on material properties determine the dose distribution in tissue and radiation detectors. Monoenergetic x-rays from synchrotron radiation offer the unique opportunity to study the dose response variation with photon energy of radiation detectors without the compounding effect of the spectral distribution of x-rays from conventional sources. The variation of dose response with photon energies between 10 and 99.6 keV was studied for two TLD materials (LiF:Mg, Ti and LiF:Mg, Cu, P), MOSFET semiconductors, radiographic and radiochromic film. The dose response at synchrotron radiation energies was compared with the one for several superficial/orthovoltage radiation qualities (HVL 1.4 mm Al to 4 mm Cu) and megavoltage photons from a medical linear accelerator. A calibrated parallel plate ionization chamber was taken as the reference dosimeter. The variation of response with x-ray energy was modelled using a two-component model that allows determination of the energy for maximum response as well as its magnitude. MOSFET detectors and the radiographic film were found to overrespond to low-energy x-rays by up to a factor of 7 and 12 respectively, while the radiochromic film underestimated the dose by approximately a factor of 2 at 24 keV. The TLDs showed a slight overresponse with LiF:Mg, Cu, P demonstrating better tissue equivalence than LiF:Mg, Ti (maximum deviation from water less than 25%). The results of the present study demonstrate the usefulness of monoenergetic photons for the study of the energy response of radiation detectors. The variations in energy response observed for the MOSFET detectors and GAF chromic film emphasize the need for a correction for individual dosimeters if accurate dosimetry of low- to medium-energy x-rays is attempted.

Kron, Tomas; Duggan, Lisa; Smith, Tony; Rosenfeld, Anatoly; Butson, Martin; Kaplan, Greg; Howlett, Steve; Hyodo, Kazuyuki

1998-11-01

56

Radiation response issues for infrared detectors  

NASA Technical Reports Server (NTRS)

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.

Kalma, Arne H.

1990-01-01

57

Radiation environment and shielding for a high luminosity collider detector  

Microsoft Academic Search

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

M. V. Diwan; Yu Fisyak; N. V. Mokhov; D M Lee; G H Sanders; L Waters; W B Wilson; B Moore; M D Marx; C R Wuest; John P Rutherfoord; C Zeitnitz; Yu V Efremenko; V L Morgunov; A Smirnov

1995-01-01

58

GaN as a radiation hard particle detector  

Microsoft Academic Search

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

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

2007-01-01

59

Beamline transition radiation detector for MW  

SciTech Connect

Recent developments of transition radiation detectors (TRD's) indicate that an efficient and practical system can be deployed for beam line particle tagging for momenta greater than 200 GeV/c. This note describes the design of a prototype system to be tested at Fermilab in Fall, 1983. Pre-prototype testing was done at BNL in March, 1983 and has been followed up by bench testing of gasses and electronics at Fermilab. The design goal is a modular system which puts few contraints on beam line configuration and hence can be adapted to any high energy secondary beam.

Haggerty, H.

1983-06-06

60

Radiation detector having a multiplicity of individual detecting elements  

DOEpatents

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.

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

1985-01-01

61

Space Radiation Detector with Spherical Geometry  

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

62

Response of converter semiconductor detectors on neutron radiation  

Microsoft Academic Search

Active detectors based on Si semiconductors are being developed for individual radiation protection purposes in mixed neutron and photon fields. These devices are constructed as combined converter semiconductor detectors. Incident neutrons interact with the converter or detector nuclei and produce charged particles that can deposit energy in the semiconductor and cause a signal. The aim of this work is the

G. Fehrenbacher; J. Biersack; E. Cordes; W. Wahl

1997-01-01

63

Afterglow effects in cadmium telluride radiation detectors  

NASA Astrophysics Data System (ADS)

Cadmium Telluride (CdTe) has been investigated for many years as detector operating in the current mode, when illuminated by X- or gamma-ray beams. Indeed, applications in Non Destructive Testing (NDT) and the nuclear medicine field would be quite of interest, due to the relatively lower dose of radiation needed for a similar investigation. In these earlier investigations, three limitations, three limitations appeared drastically: photomemory effect (afterglow), high dark current and instability of this dark current. In a systematic investigation, we have measured by Photo-Induced Current Transient Spectroscopy (PICTS) the afterglow effect of a large number of detectors using various starting materials, with different kinds of compensation or chemical dopants as well as different surface and contact treatments. The main results of this study will be presented, correlated with the microscopic analysis of the material by both PICTS and Thermally Stimulated Current (TSC), in order to reach a clearer picture of the contribution from bulk and surface handlings to the afterglow effect.

Wurm, Patrick; Hage-Ali, Makram; Koebel, Jean M.; Ritt, Christiane; Siffert, Paul

1994-09-01

64

Pyroelectric detector development for the Radiation Measurement system  

NASA Technical Reports Server (NTRS)

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.

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

65

Real-time self-networking radiation detector apparatus  

DOEpatents

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.

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

2007-06-12

66

Radiation tolerance of the CMS forward pixel detector  

Microsoft Academic Search

In this paper we present some results on the radiation tolerance of the CMS forward pixel detector. They were obtained from a beam test at Fermilab of a pixel-detector module, which was previously irradiated up to a maximum dose of 45Mrad of protons at 200MeV. It is shown that CMS forward pixel detector can tolerate this radiation dose without any

G. B. Cerati; M. E. Dinardo; A. Florez; S. Kwan; A. Lopez; S. Magni; S. Malvezzi; D. Menasce; L. Moroni; C. R. Newsom; D. Pedrini; M. Rovere; S. Sala; P. Tan; S. Taroni; M. Turqueti; L. Uplegger

2009-01-01

67

SEMICONDUCTOR DETECTORS IN RADIATION MEDICINE: RADIOTHERAPY AND RELATED APPLICATIONS  

Microsoft Academic Search

Semiconductor radiation detectors play an important role in radiation instrumentation. They have many advantages due to their\\u000a small size, outstanding energy resolution in nuclear spectroscopy, easy pixilation for high spatial resolution and ability\\u000a of integration with readout electronics. Advancement in microelectronic industry made silicon one of the most popular material\\u000a for radiation detectors in medicine with applications in diagnostic and

ANATOLY B. ROSENFELD; Wollongong NSW

68

Radiation field mapping using a mechanical-electronic detector  

NASA Astrophysics Data System (ADS)

A method of radiation field mapping of a scanned electron beam using a Faraday-type detector and an electromechanical linear translator is presented. Utilizing this arrangement, fluence and fluence rate measurements can be made at different locations within the radiation field. The Faraday-type detector used in these experiments differs from most as it consists of a hollow stainless steel sphere. Results are presented in two- and three-dimensional views of the radiation field.

Czayka, M.; Fisch, M.

2010-04-01

69

Radiation damage resistance in mercuric iodide X-ray detectors  

NASA Astrophysics Data System (ADS)

Mercuric iodide (HgI 2) radiation detectors show great potential as ambient-temperature solid-state detectors for X-rays, gamma rays and visible light, with parameters that are competitive with existing technologies. In a previous experiment, HgI 2 detectors irradiated with 10 MeV protons, at doses up to 10 12 protons/cm 2 exhibited no damage. The 10 MeV protons represent only the low range of the spectrum of energies that are important. An experiment has been conducted at the Saturne accelerator facility at Saclay, France, to determine the susceptibility of these detectors to radiation damage by high-energy (1.5 GeV) protons. The detectors were irradiated to a fluence of 10 8 protons/cm 2. This fluence is equivalent to the cosmic radiation expected in a one-year period in space. The resolution of the detectors was measured as a function of the integral dose. No degradation in the response of any of the detectors or spectrometers was seen. It is clear from this data that HgI 2 has extremely high radiation-damage resistance, exceeding that of most other semiconductor materials used for radiation detectors. Based on the results shown to date, HgI 2 detectors are suitable for applications in which they may be exposed to high integral dose levels.

Patt, B. E.; Dolin, R. C.; Devore, T. M.; Markakis, J. M.; Iwanczyk, J. S.; Dorri, N.; Trombka, J.

1990-12-01

70

The silicon transition radiation detector: Performance and perspectives  

NASA Astrophysics Data System (ADS)

The Silicon Transition Radiation Detector (SiTRD) consists of multiple modules each composed by a radiator and a silicon strip detector operating inside a magnetic field region. This design allows to well separate inside the detector volume the charged particle with respect to the transition radiation X-rays eventually produced in the radiator. In this paper we will show the results of a beam test performed at low momenta, up to 5 GeV/c, with a reduced scale detector prototype. We have also implemented a full Monte Carlo simulation to design a SiTRD for an accelerator a cosmic ray experiment at higher momenta, up to 100 GeV/c. We have simulated two different detector configurations and we have studied their performance.

Brigida, M.; Favuzzi, C.; Fusco, P.; Gargano, F.; Giglietto, N.; Giordano, F.; Loparco, F.; Marangelli, B.; Mazziotta, M. N.; Mirizzi, N.; Rainò, S.; Spinelli, P.

2007-03-01

71

Radiation Effect On Gas Electron Multiplier Detector Performance  

SciTech Connect

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

Park, Kwang June [Korean Atomic Energy Research Institute, Daejeon, 305-600 (Korea, Republic of); Baldeloma, Edwin; Park, Seongtae; White, Andrew P.; Yu, Jaehoon [Department of Physics, University of Texas at Arlington, Arlington TX 76019 (United States)

2011-06-01

72

Large dynamic range radiation detector and methods thereof  

DOEpatents

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.

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

2012-02-14

73

Radiation environment and shielding for a high luminosity collider detector  

SciTech Connect

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.

Diwan, M.V.; Fisyak, Y.; Mokhov, N.V. [Superconducting Super Collider Lab., Dallas, TX (United States)] [and others

1995-12-01

74

Flame detector operable in presence of proton radiation  

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

75

Heat Transfer Issues in Thin-Film Thermal Radiation Detectors  

NASA Technical Reports Server (NTRS)

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.

Barry, Mamadou Y.

1999-01-01

76

Water equivalent plastic scintillation detectors in radiation therapy.  

PubMed

A review of the dosimetric characteristics and properties of plastic scintillation detectors for use in radiation therapy is presented. The detectors show many desirable qualities when exposed to megavoltage photon and electron beams, including water equivalence, energy independence, reproducibility, dose linearity, resistance to radiation damage and near temperature independence. These detectors do not require the usual conversion and/or correction factors used to convert the readings from common dosemeters to absorbed dose. Due to their small detecting volume, plastic scintillation detectors exhibit excellent spatial resolution. Detector performance, in certain specific cases, can be affected by radiation-induced light arising in the optical fibres that carry the scintillator signal to a photodetector. While this effect is negligible for photon beams, it may not be ignored for electron beams and needs to be accounted for. PMID:16882685

Beddar, A S

2006-01-01

77

Particle radiation effects on and calibration of space infrared detectors  

NASA Astrophysics Data System (ADS)

The far-infrared detectors of ESA's ISO satellite are sensitive enough to allow measurements at the limits imposed by the natural sky background. However, high-energy protons and electrons of the earth's radiation belts induce spikes, higher dark current and detector noise as well as an increased level of responsivity. These effects cause signal drifting for hours after the belt passage, resulting in a temporary loss of the detector's photometric calibration. The passage of the ISOPHOT detectors through the radiation belts has therefore been simulated in the laboratory and effective curing methods searched for to restore the detectors' photometric calibration. With a combination of bright IR-flashes of the ISOPHOT onboard calibration source and a bias boost the detectors can now be reset to within a few percent of the pre-irradiation characteristics.

Roth, G.; Wolf, J.; Lemke, D.

78

Abstracts of research reports on ''radiation detectors and their applications''.  

National Technical Information Service (NTIS)

This was an abstract collection of research reports held by Yayoi Research Group on February, 1997. In this report collection, the following items are contained: Imaging plate, fading phenomenone of fluophor, radiation monitoring system, GSD detector, pho...

1997-01-01

79

Technique of Absolute Efficiency Determination for gamma Radiation Semiconductor Detectors.  

National Technical Information Service (NTIS)

Simple technique is suggested to determine the absolute efficiency (E) of semiconductor detectors (SCD) which employs low-intensity neutron sources wide spread in scientific laboratories. The technique is based on using radioactive nuclide gamma radiation...

Vo Dak Bang Chan Dyk Tkhiep Chan Daj Ngiep Fan Tkhu Khyong, S. Gehrbish

1983-01-01

80

Planar antennas for THz radiation detector based on a MOSFET  

Microsoft Academic Search

This paper presents a design of planar antennas integrated with MOSFETs to form a THz radiation detector. The antennas have been developed on thin substrates in order to increase the detector responsivity through eliminating substrate modes responsible for electromagnetic power losses.

P. Kopyt; J. Marczewski; K. Kucharski; J. Lusakowski; W. K. Gwarek

2011-01-01

81

Silicon radiation detector analysis using back electron beam induced current  

Microsoft Academic Search

A new technique for the observation and analysis of detects in silicon radiation detectors is described. This method uses an electron beam from a scanning electron microscope (SEM) impinging on the rear side of the p+n junction of the silicon detector, which itself is active and detects the electron beam induced current (EBIC). It is shown that this current is

R. Guye; P. Jarron

1987-01-01

82

Initial performance of the Wire Imaging Synchrotron Radiation Detector  

SciTech Connect

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.

Von Zanthier, C.; Gomez Cadenas, J.J.; Kent, J.; King, M.; Watson, S. (California Univ., Santa Cruz, CA (USA)); Briggs, D.D.; Rouse, F.; Tinsman, J. (Stanford Linear Accelerator Center, Menlo Park, CA (USA))

1990-01-01

83

Proton-induced radiation damage in germanium detectors  

NASA Technical Reports Server (NTRS)

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 to the 8th protons/sq cm (proton energy: 1.5 GeV) at different operating temperatures (90 to 120 K) to induce radiation damage. Basic scientific and 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 below 110 C, while kept in their specially designed cryostats. This study shows that n-type HPGe detectors can be used in charged-particle 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.

Brueckner, J.; Koerfer, M.; Waenke, H.; Schroeder, A. N. F.; Filges, D.; Dragovitsch, P.; Englert, P. A. J.; Starr, R.; Trombka, J. I.

1991-01-01

84

A hybrid radiation detector for simultaneous spatial and temporal dosimetry.  

PubMed

In this feasibility study an organic plastic scintillator is calibrated against ionisation chamber measurements and then embedded in a polymer gel dosimeter to obtain a quasi-4D radiation detector. This hybrid dosimeter was irradiated with megavoltage x-rays from a linear accelerator, with temporal measurements of the dose rate being acquired by the scintillator and spatial measurements acquired with the gel dosimeter. The detectors employed in this study are radiologically equivalent; and we show that neither detector perturbs the intensity of the radiation field of the other. By employing these detectors in concert, spatial and temporal variations in the radiation intensity can now be detected and gel dosimeters can be calibrated for absolute dose from a single irradiation. PMID:21678102

Poole, C; Trapp, J V; Kenny, J; Kairn, T; Williams, K; Taylor, M; Franich, R; Langton, C M

2011-09-01

85

Study of high temperature semiconductor radiation detector  

NASA Astrophysics Data System (ADS)

We describe the results of our study of response/performance of CdTe Schottky diode and CZT diode detectors in the energy region 10-1330 keV and Si--PIN detector in the energy range 5--60 keV using different radioactive sources like Fe--55 , Am--241 , Cd--109 and CO--57. We have also studied performance and linearity of the charge sensitive pre-amplifiers, main amplifiers of respective detector system and multichannel analyser (MCA 8000A) from the electronics part of the system. Effort has been made to study any change/degradation in the performance of these detectors over last two years and we have not detected any degradation.

Bhandare, R. S.; Phani Kumar, P.; Shah, P.; Yadav, J. S.

86

High sensitivity radiation detector for capillary electrophoresis  

SciTech Connect

Capillary electrophoresis is an important new instrumental technique capable of high resolution separation and analysis of small quantities of nucleotides, amino acids, peptides, and proteins with very high efficiency and throughput. The unprecedented sensitivity of this technique will be useful for such new applications as in vivo labeling and identification of trace substances and single cell work. The principle limitation of this technique for radiolabeled molecules has been identified as the sensitivity of the detector, primarily due to the small sample volume (< 1 nl) and the short residence time of the sample in the detector (< 3 sec). The authors have developed a novel high-sensitivity CdTe solid-state detector used for detection of [sup 32]P-labeled biomolecules with unprecedented sensitivity. This detector can be easily retrofitted into existing CE apparatus.

Gordon, J.S.; Vasile, S.; Hazlett, T.; Squillante, M. (Radiation Monitoring Devices, Inc., Watertown, MA (United States))

1993-08-01

87

Nuclear radiation-warning detector that measures impedance  

DOEpatents

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.

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

2013-06-04

88

Radiation hardness of high resistivity magnetic Czochralski silicon detectors after gamma, neutron, and proton radiations  

Microsoft Academic Search

High resistivity magnetic Czochralski Si detectors were irradiated with 60Co gamma rays, neutrons, and protons to various doses\\/fluences, along with control float zone Si detectors. 1) It has been found that for gamma radiation, magnetic Czochralski Si detectors behave similarly to the high-temperature, long-time (HTLT) oxygenated float zone Si detectors. There is no space charge sign inversion and there is

Zheng Li; Jaakko Harkonen; Wei Chen; J. Kierstead; Panja Luukka; Eija Tuominen; Etuovine Tuovinen; Elea Verbitskaya; Vladimir Eremin

2004-01-01

89

UTILIZATION OF PHOSWICH DETECTORS FOR SIMULTANEOUS, MULTIPLE RADIATION DETECTION  

SciTech Connect

A phoswich radiation detector is comprised of a phosphor sandwich in which several different phosphors are viewed by a common photomultiplier. By selecting the appropriate phosphors, this system can be used to simultaneously measure multiple radiation types (alpha, beta, gamma and/or neutron) with a single detector. Differentiation between the signals from the different phosphors is accomplished using digital pulse shape discrimination techniques. This method has been shown to result in accurate discrimination with highly reliable and versatile digital systems. This system also requires minimal component count (i.e. only the detector and a computer for signal processing). A variety of detectors of this type have been built and tested including: (1) a triple phoswich system for alpha/beta/gamma swipe counting, (2) two well-type detectors for measuring low levels of low energy photons in the presence of a high energy background, (3) a large area detector for measuring beta contamination in the presence of a photon background, (4) another large area detector for measuring low energy photons from radioactive elements such as uranium in the presence of a photon background. An annular geometry, triple phoswich system optimized for measuring alpha/beta/gamma radiation in liquid waste processing streams is currently being designed.

William H. Miller; Manuel Diaz de Leon

2003-04-15

90

Cryogenic Si detectors for ultra radiation hardness in SLHC environment  

NASA Astrophysics Data System (ADS)

Radiation hardness up to 10 16 neq/cm 2 is required in the future HEP experiments for most inner detectors. However, 10 16 neq/cm 2 fluence is well beyond the radiation tolerance of even the most advanced semiconductor detectors fabricated by commonly adopted technologies: the carrier trapping will limit the charge collection depth to an effective range of 20-30 ?m regardless of depletion depth. Significant improvement of the radiation hardness of silicon sensors has been taken place within RD39. Fortunately the cryogenic tool we have been using provides us a convenient way to solve the detector charge collection efficiency (CCE) problem at SLHC radiation level (10 16 neq/cm 2). There are two key approaches in our efforts: (1) use of the charge/current injection to manipulate the detector internal electric field in such a way that it can be depleted at a modest bias voltage at cryogenic temperature range (?230 K); and (2) freezing out of the trapping centers that affects the CCE at cryogenic temperatures lower than that of the LN 2 temperature. In our first approach, we have developed the advanced radiation hard detectors using charge or current injection, the current injected diodes (CID). In a CID, the electric field is controlled by injected current, which is limited by the space charge, yielding a nearly uniform electric field in the detector, independent of the radiation fluence. In our second approach, we have developed models of radiation-induced trapping levels and the physics of their freezing out at cryogenic temperatures. In this approach, we intend to study the trapping effect at temperatures below LN 2 temperature. A freeze-out of trapping can certainly help in the development of ultra-radiation hard Si detectors for SLHC. A detector CCE measurement system using ultra-fast picosecond laser with a He cryostat has been built at CERN. This system can be used to find out the practical cryogenic temperature range that can be used to freeze out the radiation-induced trapping levels, and it is ready for measurements on extremely heavily irradiated silicon detectors. Initial data from this system will be presented.

Li, Zheng; Abreu, M.; Anbinderis, P.; Anbinderis, T.; Ambrosio, N. D.'.; de Boer, W.; Borchi, E.; Borer, K.; Bruzzi, M.; Buontempo, S.; Chen, W.; Cindro, V.; Dierlamm, A.; Eremin, V.; Gaubas, E.; Gorbatenko, V.; Grigoriev, E.; Hauler, F.; Heijne, E.; Heising, S.; Hempel, O.; Herzog, R.; Härkönen, J.; Ilyashenko, I.; Janos, S.; Jungermann, L.; Kalesinskas, V.; Kapturauskas, J.; Laiho, R.; Luukka, P.; Mandic, I.; De Masi, Rita; Menichelli, D.; Mikuz, M.; Militaru, O.; Niinikosky, T. O.; Shea, V. O.'.; Pagano, S.; Paul, S.; Piotrzkowski, K.; Pretzl, K.; Rato Mendes, P.; Rouby, X.; Ruggiero, G.; Smith, K.; Sonderegger, P.; Sousa, P.; Tuominen, E.; Tuovinen, E.; Verbitskaya, E.; Vaitkus, J.; Wobst, E.; Zavrtanik, M.

2007-09-01

91

Experimental studies of radiation damage of silicon detectors. Internal report  

SciTech Connect

New particle physics experiments are correlated with high luminosity and/or high energy. The new generation of colliding beam machines which will be constructed will make an extrapolation of a factor of 100 in the center of mass energy and of 1000 in luminosity beyond present accelerators. The scientific community hopes that very exciting physics results could be achieved this way, from the solution to the problem of electroweak symmetry breaking to the possible discovery of new, unpredicted phenomena. The particles which compose the radiation field are: electrons, pions, neutrons, protons and photons. It has become evident that the problem of the radiation resistance of detectors in this severe environment is a crucial one. This situation is complicated more by the fact that detectors must work all the run time of the machine, and better all the time of the experiment, without replacement (part or whole). So, studies related to the investigation of the radiation hardness of all detector parts, are developing. The studies are in part material and device characterization after irradiation, and in part technological developments, made in order to find harder, cheaper technologies, for larger surfaces. Semiconductor detectors have proven to be a good choice for vertex and calorimeter. Both fixed target machines and colliders had utilized in the past silicon junction detectors as the whole or part of the detection system. Precision beam hodoscopes and sophisticated trigger devices with silicon are equally used. The associated electronics in located near the detectors, and is subjected to the same radiation fields. Studies of material and device radiation hardness are developing in parallel. Here the authors present results on the radiation hardness of silicon, both as a bulk material and as detectors, to neutron irradiation at high fluences.

Angelescu, T.; Ghete, V.M.; Ghiordanescu, N.; Lazanu, I.; Mihul, A. [Univ. of Bucharest (Romania); Golutvin, I.; Lazanu, S.; Savin, I.; Vasilescu, A. [JINR, Dubna (Russian Federation); Biggeri, U.; Borchi, E.; Bruzzi, M. [Univ. of Florence (Italy)]|[INFN, Florence (Italy); Li, Z.; Kraner, H.W. [Brookhaven National Lab., Upton, NY (United States)

1994-02-01

92

Surface Wave Chemical Detector Using Optical Radiation.  

National Technical Information Service (NTIS)

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 le...

R. J. Warmack T. G. Thundat

2005-01-01

93

Proton-induced radiation damage in germanium detectors  

Microsoft Academic Search

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 108 protons cm-2 (proton energy: 1.5 GeV) at different operating temperatures (90 to 120 K) to induce radiation

J. Brueckner; M. Koerfer; H. Waenke; A. N. F. Schroeder; D. Filges; P. Dragovitsch; P. A. J. Englert; R. Starr; J. I. Trombka; I. Taylor; D. M. Drake; E. R. Shunk

1991-01-01

94

Recovery of radiation damage in CdTe detectors  

Microsoft Academic Search

The exposure of CdTe:Cl detectors to increasing doses\\/fluences of ionizing radiation seriously affects their spectroscopic performance and operation. We have investigated the recovery process of irradiated detectors by means of photon spectroscopy (241Am and 57 Co) and photoinduced current transient spectroscopy (PICTS) analyses, by studying the evolution with time of their spectroscopic performance and correlating it with the presence of

B. Fraboni; A. Cavallini; N. Auricchio; W. Dusi; M. Zanarini; P. Siffert

2005-01-01

95

Operation of silicon microstrip detectors in a high radiation environment  

SciTech Connect

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.

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. (Los Alamos National Lab., NM (USA)); Brooks, B.M.; Isenhower, L.D.; Sadler, M.E. (Abilene Christian Univ., TX (USA)); Lederman, L.M.; Schub, M.H. (Chicago Univ., IL (USA)); Brown, C.N.; Cooper, W.E.; Gounder, K.; Hsiung, Y.B.; Mishra, C.S. (Fermi National

1990-01-01

96

Radiation damage measurements on CZT drift strip detectors  

Microsoft Academic Search

At DSRI, in collaboration with the cyclotron facility at Copenhagen University Hospital, we have performed a study of radiation effects exposing a 2.7mm thick CZT drift strip detector to 30MeV protons. The detector characteristics were evaluated after exposure to a number of fluences in the range from 2×108 to 60×108p+\\/cm2. Even for the highest fluences, which had a dramatic effect

I. Kuvvetli; C. Budtz-Jørgensen; U. Korsbech; H. J. Jensen

2003-01-01

97

Silicon carbide detector for laser-generated plasma radiation  

NASA Astrophysics Data System (ADS)

We present the performance of a Silicon Carbide (SiC) detector in the acquisition of the radiation emitted by laser generated plasmas. The detector has been employed in time of flight (TOF) configuration within an experiment performed at the Prague Asterix Laser System (PALS). The detector is a 5 mm2 area 100 nm thick circular Nisbnd SiC Schottky junction on a high purity 4Hsbnd SiC epitaxial layer 115 ?m thick. Current signals from the detector with amplitudes up to 1.6 A have been measured, achieving voltage signals over 80 V on a 50 ? load resistance with excellent signal to noise ratios. Resolution of few nanoseconds has been experimentally demonstrated in TOF measurements. The detector has operated at 250 V DC bias under extreme operating conditions with no observable performance degradation.

Bertuccio, Giuseppe; Puglisi, Donatella; Torrisi, Lorenzo; Lanzieri, Claudio

2013-05-01

98

Three-axis asymmetric radiation detector system  

SciTech Connect

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.

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

2000-01-01

99

3D-RID - Micromaching for Radiation Imaging Detectors  

NASA Astrophysics Data System (ADS)

Recent advances in the technology of micro-machining have enabled novel topologies for radiation detector design to be proposed. This paper will describe some of the work that is being carried out to develope detector structures with enhanced detection efficiency for x-rays, reduced cross-talk and edgeless operation. All of these are essential characteristics of detectors that are needed to make large area arrays (20×40 cm) for x-ray imaging with better performance than the flat panels currently available. Other configurations such as scintillator filled structures and structures filled with other materials will also be described.

O'Shea, V.

2004-07-01

100

The Dielectric Bolometer, A New Type of Thermal Radiation Detector  

NASA Technical Reports Server (NTRS)

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.

Hanel, R. A.

1960-01-01

101

R&D for Better Nuclear Security: Radiation Detector Materials  

SciTech Connect

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.

Kammeraad, J E

2009-04-02

102

Current injected detectors (CID) - a new approach for detector operation in very high radiation environment  

Microsoft Academic Search

For the upcoming Super LHC (SLHC) experiments on the LHC upgrade, Si detectors will still be considered as the main detectors for inner tracker. However, the radiation level in SLHC will be up to 10 times more than that in LHC due to the increase of luminosity from 1034 cm-2s-1 to 1035 cm-2s-1. In this study a new approach for

V. Eremin; I. Ilyashenko; E. Verbitskaya; N. Egorov; S. Golubkov; K. Konkov; A. Sidorov; Z. Li; K. M. Smith; T. Niinikoski; J. Haerkonen

2004-01-01

103

Detector and dosimeter for neutrons and other radiation  

SciTech Connect

A radiation detector and dosimeter is based on the fact that a sufficiently finely-dispersed liquid suspended in a host liquid of high viscosity or gel is stable at temperatures above its normal boiling point for long periods of time provided it is protected from contact with walls, or other types of initiators which can cause volatilization or vaporization of the droplets. Radiation, and particularly neutron radiation of sufficient energy and intensity on coming in contact with such droplets can trigger volatilization. The volume of vapor evolved can then serve as a measure of radiation intensity and dosage.

Apfel, R.E.

1982-09-21

104

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

SciTech Connect

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.

Proudfoot, J.

1992-01-01

105

Semiconductor radiation detector with internal gain  

DOEpatents

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.

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

2003-04-01

106

Radiation Damage and Long-Term Aging in Gas Detectors  

Microsoft Academic Search

Aging phenomena constitute one of the most complex and serious potential problems which could limit, or severely impair, the use of gaseous detectors in unprecedented harsh radiation environments. Long-term operation in high-intensity experiments of the LHC-era not only demands extraordinary radiation hardness of construction materials and gas mixtures but also very specific and appropriate assembly procedures and quality checks during

Maxim Titov

2004-01-01

107

Applications of a-Si:H radiation detectors  

SciTech Connect

Device structures and operation principles are described for detecting various kinds of radiation with hydrogenated amorphous silicon (a-Si:H) layers. With some new configurations such as the buried p-i-n structure and the use of interdigitated electrodes, the a-Si:H radiation detectors will find their applications in many fields of science. Some applications in high energy physics, medical imaging, materials sciences and life sciences are discussed in this paper. 41 refs., 7 figs., 1 tab.

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

1989-07-01

108

Applications of aSi:H radiation detectors  

Microsoft Academic Search

Device structures and operation principles are described for detecting various kinds of radiation with hydrogenated amorphous silicon (a-Si:H) layers. With some new configurations such as the buried p-i-n structure and the use of interdigitated electrodes, the a-Si:H radiation detectors will find their applications in many fields of science. Some applications in high energy physics, medical imaging, materials sciences and life

I. Fujieda; G. Cho; M. Conti; J. Drewery; S. N. Kaplan; V. Perez-Mendez; S. Qureshi

1989-01-01

109

EFFECTS OF P / N IN HOMOGENEITY ON CDZNTE RADIATION DETECTORS.  

SciTech Connect

Spectrometer grade, room-temperature radiation detectors have been produced on Cd{sub 0.90}Zn{sub 0.10}Te grown by the low-pressure Bridgman technique. Small amount of indium has been used to compensate the uncompensated Cd vacancies for the crystals to be semi-insulating. The properties of the detectors are critically dependent on the amount of excess Te introduced into the growth melts of the Cd{sub 0.90}Zn{sub 0.10}Te crystals and the best detectors are fabricated from crystals grown with 1.5% excess Te. Detector resolution of {sup 57}Co and {sup 241}Am radiation peaks are observed on all detectors except the ones produced on Cd{sub 0.90}Zn{sub 0.10}Te grown from the melt in the stoichiometric condition. The lack of resolution of these stoichiometric grown detectors is explained by a p/n conduction-type inhomogeneity model.

CHU,M.; TERTERIAN,S.; TING,D.; JAMES,R.B.; SZAWLOWSKI,M.; VISSER,G.J.

2002-07-08

110

Effects of the film microstructures on CVD diamond radiation detectors  

NASA Astrophysics Data System (ADS)

The polycrystalline nature of the films has limited the improvement of CVD diamond radiation detectors. In this work, three CVD diamond films with different microstructures were grown by a hot-filament chemical vapor deposition (HFCVD) technique and were fabricated as CVD diamond radiation detectors. The photocurrents and the pulse height distributions (PHDs) obtained by the detectors were measured by using 5.9 keV 55Fe X-rays. The dark-current of 16.0 nA and the photocurrent of 15.9 nA are achieved at a bias voltage of 100 V. The PHD peak is well separated from the noise and a better energy resolution of 21.2% is obtained due to the high ratio of grain size to the film thickness. The time-dependent photocurrent initially increases rapidly and then levels off due to the 'polarization' effect.

Zhang, Minglong; Xia, Yiben; Wang, Linjun; Gu, Beibei

2005-04-01

111

Radiation Response of Emerging High Gain, Low Noise Detectors  

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

112

49 CFR 173.310 - Exceptions for radiation detectors.  

Code of Federal Regulations, 2013 CFR

...relief device. (c) Radiation detectors must be shipped in a strong outer packaging capable of withstanding a drop test of at...part of other equipment, the equipment must be packaged in strong outer packaging or the equipment itself must provide an...

2013-10-01

113

Semiconductor detectors produced by lithium diffusion simulated by thermal radiation  

Microsoft Academic Search

A method for preparation of semiconductors (SD) with thin (10-20 micrometer) dead layers is described. Unlike the traditional technology, lithium diffusion by means of pulses of thermal radiation in the presence of a temperature gradient in the specimen is used to reduce the depth of the pn junction. The proposed method provides semiconductor detectors with parameters that bring the energy

M. G. Gornov; Yu. B. Gurov; Z. T. Kim; C. Y. Kim; B. P. Osipenko; J. Jurkowski

1988-01-01

114

Radiations from nuclear weapons - signal detectors - NASA program information  

Microsoft Academic Search

This letter is for the purpose of supplying the information that you requested at the meeting of the sub-committee on Project Vela. It is divided into three parts: (1) Radiations from nuclear weapons; (2) Backgrounds for Vela Signal Detectors; (3) Discussion of the NASA program.

1960-01-01

115

Research on radiation detectors, boiling transients, and organic lubricants  

NASA Technical Reports Server (NTRS)

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.

1974-01-01

116

Synchrotron radiation applications of charge coupled device detectors (invited)  

SciTech Connect

Scientific charge coupled devices (CCDs) offer many opportunities for high brightness synchrotron radiation applications where good spatial resolution and fast data acquisition are important. We describe the use of virtual-phase CCD pixel arrays as two-dimensional area detectors illustrating the techniques with results from recent x-ray scattering, imaging, and absorption spectroscopy studies at NSLS, CHESS, SRC, and LURE DCI. The virtual phase architecture allows direct frontside illumination of the CCD detector chips giving advantages in the speed and sensitivity of the detector. Combining developments in x-ray optics (dispersive geometry), position sensitive area detectors (CCDs), and fast data acquisition, we have been able to perform time-resolved measurements at the microsecond level. Current developments include faster data transfer rates so that the single bunch timing structure of third generation synchrotron sources can be exploited.

Clarke, R. (University of Michigan, Department of Physics, Ann Arbor, Michigan 48109-1120 (United States)); Lowe, W.P.; MacHarrie, R.A. (AT T Bell Laboratories, Murray Hill, New Jersey 07974-2070 (United States)); Brizard, C.; Rodricks, B.G. (Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States))

1992-01-01

117

Simulation and test of 3D silicon radiation detectors  

NASA Astrophysics Data System (ADS)

The work presented here is the result of the collaborative effort between the University of Glasgow, ITC-IRST (Trento) and IMB-CNM (Barcelona) in the framework of the CERN-RD50 Collaboration to produce 3D silicon radiation detectors and study their performance. This paper reports on two sets of 3D devices. IRST and CNM have fabricated a set of single-type column 3D detectors, which have columnar electrodes of the same doping type and an ohmic contact located at the backplane. Simulations of the device behaviour and electrical test results are presented. In particular, current-voltage, capacitance-voltage and charge collection efficiency measurements are reported. Other types of structures called double-sided 3D detectors are currently being fabricated at CNM. In these detectors the sets of n and p columns are made on opposite sides of the device. Electrical and technological simulations and first processing results are presented.

Fleta, C.; Pennicard, D.; Bates, R.; Parkes, C.; Pellegrini, G.; Lozano, M.; Wright, V.; Boscardin, M.; Dalla Betta, G.-F.; Piemonte, C.; Pozza, A.; Ronchin, S.; Zorzi, N.

2007-09-01

118

Two-dimensional position sensitive radiation detectors  

DOEpatents

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.

Mihalczo, J.T.

1994-02-22

119

Three-dimensional architecture for solid state radiation detectors  

DOEpatents

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.

Parker, Sherwood (Berkeley, CA)

1999-01-01

120

Three-dimensional architecture for solid state radiation detectors  

DOEpatents

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.

Parker, S.

1999-03-30

121

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

SciTech Connect

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.

Mueller, G.M.

1983-12-01

122

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

SciTech Connect

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.

Mueller, G.M.

1984-01-01

123

Radiation physical chemistry effects on organic detectors  

NASA Astrophysics Data System (ADS)

The radiation damage effect on a liquid scintillating system was evaluated in the PPO and POPOP solutes. Samples containing PPO (1%w/v) and POPOP (0.2%w/v) diluted in toluene were irradiated at different doses, using a 60Co irradiator at 1.8 Gy/s. The transmittance and the chemical degradation of those solutes were evaluated as a function of dose. The PPO transmittance at 360 nm decayed exponentially with the dose, while the POPOP transmittance at 420 nm decayed linearly. The chemical degradation on the PPO and POPOP was fitted to a bi-exponential mathematical model as a function of dose. The first exponential (fast slope) was interpreted as damage produced by toluene radiolytics whereas the second exponential (slow slope) was interpreted as the damage caused by primary interaction of the ?-radiation with targets, i.e., ? photons that hit PPO and POPOP directly. The w (eV/damage molecule) and G (damaged molecules/100 eV) parameters were estimated in this paper.

Mesquita, C. H.; Duarte, C. L.; Hamada, M. M.

2003-06-01

124

Test of radiation detectors used in homeland security applications.  

PubMed

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. PMID:15824588

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

2005-05-01

125

Examination results of the Three Mile Island radiation detector HP-R-213  

SciTech Connect

Area radiation detector HP-R-213 was removed from the Three Mile island containment building on May 28, 1981. The detector apparently failed at the time of the hydrogen burn, and afterwards indicated radiation levels of less than 0.1 mR/h. 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.

Mueller, J.M.

1982-11-01

126

Studies of high temperature superconductors as radiation detectors  

NASA Astrophysics Data System (ADS)

Both DyBaCuO (DBCO) and YBaCuO (YBCO) films deposited on a variety of substrates have been investigated for their applicability as detectors of high frequency radiation. Both 10 GHz and infrared radiation (IR) were used as the high frequency radiation source. The measurements consisted of monitoring the temperature dependent resistance of superconducting films both in the presence and absence of radiation. This investigation shows that because the superconducting transition temperature is sensitive to the magnitude of the current in the film, the temperature dependence of the bolometric response is slightly tunable. In addition, effects of radiation on the current voltage characteristics below T superconducting were studied. This study found that films in this regime could also serve as radiation detectors. The substrates used included MgO, SiO, LaAlO(subscript 3), and SrTiO(subscript 3). The results obtained were independent of the substrate except for the width of the resistive transition. Disorder in the films as characterized by the resistive transition, affected the microwave more than the IR response.

Qiu, A.; Bhattarai, A. R.; Dahlberg, E. D.; Khan, M. Asif; Moloni, K.; van Hove, James M.

1992-12-01

127

Multipurpose High Sensitivity Radiation Detector: Terradex  

NASA Astrophysics Data System (ADS)

Terradex project aims to realise an accurate and programmable multiparametric tool which will measure relevant physical quantities such as observation time, energy and type of all decay products of three naturally occurring decay chains of uranium and thorium series present in nature as well as the decay products of man-made radioactivity. The measurements described in this work are based on the performance tests of the first version of an instrument that is designed to provide high counting accuracy, by introducing self-triggering, delayed time-coincidence technique, of products of a given decay chain. In order to qualify the technique and to calibrate the Terradex, a 222Rn source is used. The continuous and accurate monitoring of radon concentration in air is realised by observing the alpha and beta particles produced by the decay of 222Rn and its daughters and tag each of them with a precise occurrence time. The validity of delayed coincident technique by using the state of the art electronics with application of novel data sampling and analysis methods are discussed. The flexibility of sampling protocols and the advantages of online calibration capability to achieve the highest level of precision in natural and man-made radiation measurements are also described.

Alpat, Behcet; Aisa, Damiano; Bizzarri, Marco; Blasko, Sandor; Esposito, Gennaro; Farnesini, Lucio; Fiori, Emmanuel; Papi, Andrea; Postolache, Vasile; Renzi, Francesca; Ionica, Romeo; Manolescu, Florentina; Ozkorucuklu, Suat; Denizli, Haluk; Tapan, Ilhan; Pilicer, Ercan; Egidi, Felice; Moretti, Cesare; Dicola, Luca

2007-05-01

128

Super-thin single crystal diamond membrane radiation detectors  

NASA Astrophysics Data System (ADS)

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

Pomorski, Michal; Caylar, Benoit; Bergonzo, Philippe

2013-09-01

129

Super-thin single crystal diamond membrane radiation detectors  

SciTech Connect

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

Pomorski, Michal; Caylar, Benoit; Bergonzo, Philippe [CEA-LIST, Diamond Sensors Laboratory, Gif-sur-Yvette F-91191 (France)] [CEA-LIST, Diamond Sensors Laboratory, Gif-sur-Yvette F-91191 (France)

2013-09-09

130

Experiences with radiation portal detectors for international rail transport  

SciTech Connect

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.

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

2006-08-30

131

HgS: a rugged, stable semiconductor radiation detector material  

NASA Astrophysics Data System (ADS)

Many materials used in radiation detectors are environmentally unstable and/or fragile. These properties are frustrating to researchers and add significantly to the time and cost of developing new detectors as well as to the cost of manufacturing products. The work presented here investigates the properties of HgS. This material was selected for study based partly on its inherent stability and ruggedness, high density, high atomic number, and bandgap. HgS is found in nature as the mineral cinnabar. A discussion of the physical properties of HgS, experimental characterization of natural cinnabar, and initial radiation detection results are presented along with a discussion of potential crystal growth techniques for producing crystals of HgS in the laboratory.

Squillante, Michael R.; Higgins, William M.; Kim, Hadong; Cirignano, Leonard; Ciampi, Guido; Churilov, Alexei; Shah, Kanai

2009-08-01

132

A precision synchrotron radiation detector using phosphorescent screens  

SciTech Connect

A precision detector to measure synchrotron radiation beam positions has 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. 3 refs., 5 figs., 1 tab.

Jung, C.K.; Lateur, M.; Nash, J.; Tinsman, J. (Stanford Linear Accelerator Center, Menlo Park, CA (USA)); Butler, J. (Fermi National Accelerator Lab., Batavia, IL (USA)); Wormser, G. (Paris-11 Univ., 91 - Orsay (France). Lab. de l'Accelerateur Lineaire); Levi, M.; Rouse, F. (Lawrence Berkeley Lab., CA (USA))

1990-01-01

133

Progress in ultra-low-noise ASICs for radiation detectors  

Microsoft Academic Search

The progress of a research aimed to design CMOS front-end with noise level down to few electrons r.m.s. is presented. The interest in ultra-low-noise Application-Specific Integrated Circuits (ASICs) has been stimulated by silicon carbide pixel radiation detectors with negligible electronic noise at room temperature due to leakage currents in the femtoampere range. An experimental study on the 1\\/f noise of

Giuseppe Bertuccio; Stefano Caccia

2007-01-01

134

3D silicon detectors and radiation hardness issues  

Microsoft Academic Search

3D silicon technology is a new way to make silicon detectors using Micro-Electro-Mechanical-Systems (MEMS) processing. In this innovative design the electrodes penetrate throughout the silicon bulk perpendicular to the surface. Radiation hardness of 3D and planar devices is compared. A formalism describing the dependence of charge collection efficiency on fluence is derived and compared with data. It is shown to

C. DaVia; G. Anelli; J. Hasi; P. Jarron; C. Kenney; A. Kok; S. Parker; S. J. Watts

2005-01-01

135

Fabrication techniques for reverse electrode coaxial germanium nuclear radiation detectors  

SciTech Connect

Germanium detectors with reverse polarity coaxial electrodes have been shown to exhibit improved resistance to radiation damage as compared with conventional electrode devices. However, the production of reverse electrode devices involves the development of new handling and fabrication techniques which has limited their wider application. We have developed novel techniques which lead to a device which is simple to fabricate, environmentally passivated and surface state adjusted.

Hansen, W.L.; Haller, E.E.

1980-11-01

136

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

Microsoft Academic Search

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

Wen-Hsing Hsu

2002-01-01

137

Field Testing of a Portable Radiation Detector and Mapping System  

SciTech Connect

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.

Hofstetter, K.J. [Westinghouse Savannah River Company, AIKEN, SC (United States); Hayes, D.W.; Eakle, R.F.

1998-03-01

138

An Intelligent Radiation Detector System For Remote Monitoring  

NASA Astrophysics Data System (ADS)

A unique real-time gamma radiation detector and spectroscopic analyzer, specifically designed for a ``Homeland Security Radiological Network'', has been developed by the Environmental Measurements Laboratory (EML). The Intelligent Radiation Detector's (IRD) sensitivity and rapid sampling cycle assure up-to-the minute radiological data, which will indicate fast changes in atmospheric radioactivity. In addition, an immediate alert will occur within seconds to signal rapid changes in activity or levels elevated beyond a preset. This feature is particularly valuable to detect radioactivity from moving vehicles. The IRD also supplies spectral data, which allows the associated network computer to identify the specific radionuclides detected and to distinguish between natural and manmade radioactivity. To minimize cost and maximize rapid availability, the IRD uses readily available ``off the shelf'' components combined with an inexpensive, unique detector housing made of PVC plastic pipe. Reliability with no required maintenance is inherent in the IRD, which operates automatically and unattended on a ``24/7'' basis. A prototype unit installed on EML's roof has been in continuous operation since November 27, 2001.

Latner, Norman; Chiu, Norman; Sanderson, Colin G.

2002-10-01

139

Applications of Noble Gas Radiation Detectors to Counter-terrorism  

NASA Astrophysics Data System (ADS)

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

Vanier, Peter E.; Forman, Leon

2002-10-01

140

Miniature scintillating detector for small field radiation therapy.  

PubMed

In planning stereotactic radiosurgery treatments, depth dose curves, profiles, and dose rate of treatment beams are difficult to obtain with conventional detectors because of loss of lateral electronic equilibrium and volume averaging. A scintillating detector with high spatial resolution and good reliability has been developed to overcome this problem. The miniature dosimeter consists of two identical radiation-resistant 10 m long silica optical fibers, each connected to an independent silicon photodiode. A small cylindrical polystyrene scintillator (3.9 mm3) is optically glued to the detection fiber. The light seen by the photodiode connected to this fiber arises from fluorescence of the scintillator and from the Cerenkov effect produced in silica. The reference signal produced by the fiber without scintillator is used to subtract the Cerenkov light contribution from the raw detector response. The sensitive volume of the scintillating detector is nearly water-equivalent and thus minimizes dose distribution perturbation in water. The miniature dosimeter has a spatial resolution comparable to the film-densitometer system. Profiles of 1 cm diam, 6 MV photon beam measured with both systems show very similar shapes. Furthermore, the use of photodiodes instead of photomultiplier tubes gives a better stability response and offers the possibility to perform absolute dosimetry. PMID:10619239

Létourneau, D; Pouliot, J; Roy, R

1999-12-01

141

Radiation detector resolution over a continuous energy range  

SciTech Connect

Urgent need for new radiation detector materials with excellent energy resolution at room temperature has prompted research efforts on both accelerated materials discovery and efficient techniques that can investigate candidate materials to identify material properties relevant to detector performance. In this work, an ion-beam approach is demonstrated to obtain energy resolution in both semiconductor detectors and scintillators over a continuous energy range. For semiconductors, the energy resolution of a silicon detector was measured as a function of He+ ion energy, and the values from an extrapolation to high energies are in good agreement with the literature data from alpha measurements. For the scintillators, benchmark crystals of BGO, YAP(Ce) and CsI(Tl) subject to He+ irradiation were investigated, and the corresponding energy resolution is compared with gamma-ray tests on the same crystals. The agreement of energy resolution between the ion and gamma measurements indicates that the ion approach can be used to predict energy resolution of candidate materials in thin film form (a few tens ?m thick) or a small crystals (a few mm3), when large crystals necessary for gamma-ray testing are unavailable.

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

2007-08-27

142

Phonon-mediated detectors of radiation: state of the art  

NASA Astrophysics Data System (ADS)

Basic operation principles of phonon-mediated low-temperature detectors of radiation are briefly reviewed. Physical properties required for the energy absorbers and for the phonon sensors of the detectors are introduced and discussed. Semiconductor thermistors, superconductive tunnel junctions and transition edge films as phonon sensors are presented and critically compared. State-of-art of single quantum detection with these devices is reported. Particular emphasis is given to the detection of X-rays and Gamma-rays. In this field, low temperature devices can provide higher efficiency and energy resolution than conventional technology. The main point is that phonon-mediated low temperature detectors are characterized by a large flexibility in the choice of the material for the active part of the device. High Z materials with the proper thermal properties can therefore be selected, providing at the same time high efficiency and high signal-to-noise ratio. The unique features of low temperature detectors allow their use in many fields, ranging from fundamental physics (neutrino properties, dark matter search, astronomy) to industrial applications (X-ray fluorescence analysis).

Giuliani, Andrea

2001-12-01

143

Experimental comparison of discrete and CMOS charge sensitive preamplifiers for CZT radiation detectors  

Microsoft Academic Search

During recent years, many readout integrated circuits for CZT radiation detectors have been studied particularly for use on pixilated detectors in imaging applications. The main challenge is to keep noise performance similar to discrete preamplifiers, even with lower power. This paper presents the design and the experimental evaluation of CMOS integrated charge sensitive preamplifiers intended for CZT radiation detectors. A

Guillaume Montémont; Jean-Pierre Rostaing; Loïck Verger

2002-01-01

144

Radiation Damage Measurements on Double-Sided Si Strip Detectors (Abstract Only).  

National Technical Information Service (NTIS)

Results from radiation tests on new double sided microstrip detectors are presented. The radiation effects on the detectors were studied using a Co-60 gamma source. The test results suggest a modification in the detector layout design, which would lead to...

I. Hietanen M. Laakso T. Schulman T. Tuuva

1991-01-01

145

Experimental comparison of discrete and CMOS charge sensitive preamplifiers for CZT radiation detectors  

Microsoft Academic Search

During recent years, many readout integrated circuits for CdZnTe (CZT) radiation detectors have been studied particularly for use on pixellated detectors in imaging applications. The fundamental challenge is to keep noise performance similar to discrete preamplifiers, even with lower power. This paper presents an experimental evaluation of CMOS integrated charge sensitive preamplifiers intended for CZT radiation detectors using a comparison

Guillaume Montémont; Jean-Pierre Rostaing; Loïck Verger

2003-01-01

146

X-ray machine, solid state radiation detector and method for reading radiation detection information  

US Patent & Trademark Office Database

A solid state radiation detector having an improved method of reading data from individual sensors and an x-ray machine configured with such a solid state radiation detector. At least one sensor of the solid state radiation detector is designated as a reference sensor. The output of the reference sensor is read until it reaches a predetermined threshold. Once the threshold has been reached, a timer determines when the predetermined x-ray exposure time is completed. Upon completion, the sensors of the solid state radiation sensor are read. Thus, all sensors may be read at the proper time to achieve maximum output in spite of an unknown and variable warm-up period for the x-ray tube following activation and possibly an unknown exposure time. Alternatively, once the output of the reference has reached the predetermined threshold, the output of that reference continues to be monitored to determine when the output of the reference sensor falls below a second predetermined threshold. At approximately that time, all sensors of the solid state radiation detector are read.

1995-08-22

147

3D — A proposed new architecture for solid-state radiation detectors  

Microsoft Academic Search

A proposed new architecture for solid-state radiation detectors using a three-dimensional array of electrodes that penetrate into the detector bulk is described. Proposed fabrication steps are listed. Collection distances and calculated collection times are about one order of magnitude less than those of planar technology strip and pixel detectors with electrodes confined to the detector surface, and depletion voltages are

S. I. Parker; C. J. Kenney; J. Segal

1997-01-01

148

Two-dimensional position sensitive transition radiation detector  

NASA Astrophysics Data System (ADS)

A new transition radiation detector (TRD) prototype foreseen to fulfill the requirements of the TRD subdetector of the CBM experiment at FAIR has been designed, constructed and tested with electrons and pions of a few GeV/c. The detector prototype was build with the original TRD architecture which preserves the high conversion efficiency of transition radiation in a single TRD layer. This TRD architecture is based on two multiwire proportional chambers readout by a common double-sided pad read-out electrode. The triangular shape of the readout pads gives access to the position information in both coordinates which defines the readout electrode plane. Pion efficiency as a function of number of TRD layers and position resolution were studied using electron and pion beams delivered by PS at CERN. Dedicated front-end electronics, designed for high counting rate environment was used. An extrapolated pion efficiency of 0.5% for a six layer TRD configuration at 90% electron efficiency using a regular foil radiator was obtained. The position resolution across the pads is of the order of 320 ?m and along the pads of 5.5 mm.

Petri?, M.; Petrovici, M.; C?t?nescu, V.; Simion, V.; Barto?, D.; Berceanu, I.; Bercuci, A.; Caragheorgheopol, G.; Constantin, F.; Târzil?, M.; Bergmann, C.; Emschermann, D.; Linev, S.; Müller, W. F. J.; Wessels, J. P.

2013-06-01

149

IceCube: A Cubic Kilometer Radiation Detector  

SciTech Connect

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.

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

2008-06-01

150

Device for Growing and Thermal Treatment of Silver Chloride Sheets as Detectors of Ionizing Radiation.  

National Technical Information Service (NTIS)

A short review on technology of preparing AgCl crystals as detectors of ionizing radiation is given. The device, constructed for growing and thermal treatment of these crystals is described. Since sensitivity of crystals as detectors is strongly influence...

F. Bradna V. Bradnova F. Yukl

1983-01-01

151

Measurement of the radiation field surrounding the Collider Detector at Fermilab  

SciTech Connect

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.

K. Kordas et al.

2004-01-28

152

Radiation hardness of punch-through and FET biased silicon microstrip detectors  

Microsoft Academic Search

Silicon microstrip detectors can be biased with polysilicon resistors or Field Effect Transistor (FET) biasing structures. Polysilicon resistors are radiation hard, but using the FET biasing principle reduces processing costs and can give better noise performance. A set of microstrip detectors has been manufactured with a standard radiation sensor process in order to assess the radiation hardness of punch-through and

Trond I. Westgaard; Berit S. Avset; Niaz N. Ahmed; Lars Evensen

1996-01-01

153

Measuring the radiation field and radiation hard detectors at JET: Recent developments  

NASA Astrophysics Data System (ADS)

Since in ITER the radiation field will be much more demanding than that of present day devices, research programmes at JET are aimed at developing radiation hard diagnostics and related components. Initially, significant efforts are devoted to determining the radiation field of both the plasma and in the immediate environment with better accuracy. New developments in MCNP calculations and dedicated measurements provide useful information about the radiation field in the Torus Hall, even during non-operational periods. The effect of using Beryllium in the near future for JET first wall, is being assessed. New materials for activation samples are under consideration and will be tested to improve the calibration accuracy of JET neutron diagnostics. The long-term goal of this work is to obtain spectrometric information from an appropriate combination of different materials. Several studies are under way to modify the radiation field at the detectors by using LiH or pure water as neutron filters, to alleviate the problem of the background in ?-ray measurements. A suite of radiation hard detectors for neutrons, magnetic field and charged particles are being developed. Super-heated fluid neutron detectors, used for yield and imaging, are being upgraded, in order to provide a broad-band spectrometric capability. Chemical vapour deposited diamond diodes are being qualified as counters and as spectrometers. Prototypes of Hall probes made of InSb have been installed on the machine and have provided some preliminary results. Si-on-insulator detectors are under development for use in neutral particle analysers and are currently being bench-tested. Some attention is being devoted to optical components, fibres and mirrors, and to investigating radiation hard electronics using reconfigurable Field Programmable Gate Arrays.

Murari, A.; Edlington, T.; Angelone, M.; Bertalot, L.; Bolshakova, I.; Bonheure, G.; Brzozowski, J.; Coccorese, V.; Holyaka, R.; Kiptily, V.; Lengar, I.; Morgan, P.; Pillon, M.; Popovichev, S.; Prior, P.; Prokopowicz, R.; Quercia, A.; Rubel, M.; Santala, M.; Shevelev, A.; Syme, B.; Vagliasindi, G.; Villari, R.; Zoita, V. L.; JET-EFDA Contributors

154

Performance of the AMS-02 transition radiation detector  

NASA Astrophysics Data System (ADS)

For cosmic particle spectroscopy on the International Space Station the AMS experiment will be equipped with a Transition Radiation Detector (TRD) to improve particle identification. The TRD has 20 layers of fleece radiator with Xe/CO2 proportional-mode straw-tube chambers. They are supported in a conically shaped octagon structure made of CFC-Al-honeycomb. For low power consumption VA analog multiplexers are used as front-end readout. A 20 layer prototype built from final design components has achieved proton rejections from 100 to 2000 at 90% electron efficiency for proton beam energies up to 250 GeV with cluster counting, likelihood and neural net selection algorithms.

Doetinchem, Ph. V.; Fopp, S.; Karpinski, W.; Kirn, Th.; Lübelsmeyer, K.; Orboeck, J.; Schael, S.; Schultz von Dratzig, A.; Schwering, G.; Siedenburg, Th.; Siedling, R.; Wallraff, W.; Becker, U.; Burger, J.; Henning, R.; Kounine, A.; Koutsenko, V.; Wyatt, J.

2006-03-01

155

Low Energy Electron Detector for Space Radiation Measurements  

NASA Astrophysics Data System (ADS)

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

Hajdas, Wojtek

156

High field CdS detector for infrared radiation  

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

157

Development of Radiation Hard Silicon Detectors:. the Smart Project  

NASA Astrophysics Data System (ADS)

The research actitvity of the SMART project, a collaboration of Italian research institutes funded by the I.N.F.N., has been focused on the development of radiation hard silicon position sensitive detectors for the CERN Large Hadron Collider luminosity upgrade. Electrical characterization of pad and micro-strip devices as well as study of microscopic defects on the bulk material have been carried out on silicon 4" wafers of n- and p-type, grown with Standard Float Zone (SFz), high resistivity Magnetic Czochralski (MCz) and epitaxial (EPI) techniques. Manufactured devices have been irradiated with 24 GeV/c and 26 MeV protons up to ~ 3·1015 cm-2 1 MeV neutrons eq. (neq/cm2) and with reactor neutrons up to ~8·1015 neq/cm2. Preliminary results of measurements before and after irradiations as well as material radiation hardness are shown and discussed.

Messineo, A.; Borrello, L.; Segneri, G.; Sentenac, D.; Creanza, D.; Depalma, M.; Manna, N.; Radicci, V.; Borchi, E.; Bruzzi, M.; Focardi, E.; Macchiolo, A.; Menichelli, D.; Scaringella, M.; Tosi, C.; Bisello, D.; Candelori, A.; Khomenkov, V.; Petasecca, M.; Pignatel, G. U.; Boscardin, M.; Dalla Betta, G.-F.; Piemonte, C.; Ronchin, S.; Zorzi, N.

2006-04-01

158

Ambient temperature cadmium zinc telluride radiation detector and amplifier circuit  

DOEpatents

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.

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

1998-05-26

159

Ambient temperature cadmium zinc telluride radiation detector and amplifier circuit  

DOEpatents

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.

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

1998-05-29

160

Experiences in flip chip production of radiation detectors  

NASA Astrophysics Data System (ADS)

Modern imaging devices often require heterogeneous integration of different materials and technologies. Because of yield considerations, material availability, and various technological limitations, an extremely fine pitch is necessary to realize high-resolution images. Thus, there is a need for a hybridization technology that is able to join together readout amplifiers and pixel detectors at a very fine pitch. This paper describes radiation detector flip chip production at VTT. Our flip chip technology utilizes 25-?m diameter tin-lead solder bumps at a 50-?m pitch and is based on flux-free bonding. When preprocessed wafers are used, as is the case here, the total yield is defined only partly by the flip chip process. Wafer preprocessing done by a third-party silicon foundry and the flip chip process create different process defects. Wafer-level yield maps (based on probing) provided by the customer are used to select good readout chips for assembly. Wafer probing is often done outside of a real clean room environment, resulting in particle contamination and/or scratches on the wafers. Factors affecting the total yield of flip chip bonded detectors are discussed, and some yield numbers of the process are given. Ways to improve yield are considered, and finally guidelines for process planning and device design with respect to yield optimization are given.

Savolainen-Pulli, Satu; Salonen, Jaakko; Salmi, Jorma; Vähänen, Sami

2006-09-01

161

Degradation of silicon AC-coupled microstrip detectors induced by radiation  

Microsoft Academic Search

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. The long-term postirradiation behavior

N. Bacchetta; D. Bisello; C. Canali; P. G. Fuochi; Y. Gotra; A. Paccagnella; G. Verzellesi

1993-01-01

162

Degradation of silicon AC-coupled microstrip detectors induced by radiation damage  

Microsoft Academic Search

Results are presented showing the radiation response of FOXFET (field-oxide field effect transistor) biased AC-coupled microstrip detectors and related test patterns to be used in the CDF microvertex detector. The 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. The long-term post-irradiation behavior of

N. Bacchetta; D. Bisello; Y. Gotra; A. Paccagnella; G. Verzellesi; C. Canali; P. G. Fuochi

1992-01-01

163

Miniature CdZnTe Detectors for application in high intensity radiation fields  

Microsoft Academic Search

Presently room-temperature CdZnTe (CZT) nuclear radiation detectors of various designs and sizes are widely used for spectrometric measurements of X and gamma-radiations. In most cases the spectrometric detectors with highest efficiency are required1. But there are tasks where good spectrometric detectors with a low efficiency should be applied. Those are tasks connected with spectrometric measurements in strong radiation fields where

V. Ivanov; L. Aleksejeva; P. Dorogov; A. Loutchanski

2008-01-01

164

Methodology for Assessing Radiation Detectors Used by Emergency Responders  

SciTech Connect

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.

Piotr Wasiolek; April Simpson

2008-03-01

165

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

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.

Knoll, G.F.

1995-11-01

166

Field-deployable gamma-radiation detectors for DHS use  

NASA Astrophysics Data System (ADS)

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 identiFINDERTM, 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 RadReachBackTM 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 software-triggers the digital camera to take a snapshot. The spectral data including in situ analysis and the imagery data will be packaged in a suitable format and sent to a command post using an imbedded cell phone.

Mukhopadhyay, Sanjoy

2007-09-01

167

Field Deployable Gamma Radiation Detectors for DHS Use  

SciTech Connect

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

Sanjoy Mukhopadhyay

2007-08-31

168

Field Deployable Gamma Radiation Detectors for DHS Use  

SciTech Connect

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

Sanjoy Mukhopadhyay

2007-08-01

169

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

National Technical Information Service (NTIS)

Hydrogenated amorphous silicon and related materials have been applied to radiation detectors, utilizing their good radiation resistance and the feasibility of making deposits over a large area at low cost. Effects of deposition parameters on various mate...

W. S. Hong

1995-01-01

170

Improved detector for the measurement of gamma radiation  

NASA Astrophysics Data System (ADS)

The present invention lies in the field of gamma ray spectrometry of geologic deposits and other materials, such as building materials (cement, asphalt, etc.) More specifically, the invention is an improved device for the gamma ray spetcrometery of gelogical deposits as a tool for petroleum exploration, geologic research and monitoring of radio-active materials such as in uranium mill tailings and the like. Improvement consists in enlarging the area of the receptor face and without any necessarily substantial increase in the volume of the receptor crystal over the current cylindrical shapes. The invention also provides, as a corollary of the increase in area receptor crystal face, a reduction in the weight of the amount of material necessary to provide effective shielding of the crystal from atmospheric radiation and radiation from deposits not under examination. The area of the receptor crystal face is increased by forming the crystal as a truncated cone with the shielding shaped as a hollow frustrum of a cone. A photomultiplier device is secured to the smaller face of the crystal. The improved detector shape can also be used in scintillometers which measure total gamma radiation.

Zelt, F. B.

1985-07-01

171

Investigation of design parameters for radiation hard silicon microstrip detectors  

NASA Astrophysics Data System (ADS)

In the context of the development of radiation hard silicon microstrip detectors for the CMS Tracker, we have investigated the dependence of interstrip and backplane capacitance as well as depletion and breakdown voltage on the design parameters and substrate characteristics of the devices. Measurements have been made for strip pitches between 60 and 240 ?m and various strip implants and metal widths, using multi-geometry devices, fabricated on wafers of either <1 1 1> or <1 0 0> crystal orientation, of resistivities between 1 and 6 k? cm and of thicknesses between 300 and 410 ?m. The effect of irradiation on properties of devices has been studied with 24 GeV/c protons up to a fluence of 4.3×10 14 cm-2.

Braibant, S.; Demaria, N.; Feld, L.; Frey, A.; Fürtjes, A.; Glessing, W.; Hammarström, R.; Honma, A.; Mannelli, M.; Mariotti, C.; Mättig, P.; Migliore, E.; Piperov, S.; Runolfsson, O.; Schmitt, B.; Söldner-Rembold, A.; Surrow, B.

2002-06-01

172

BOBCAT Personal Radiation Detector Field Test and Evaluation Campaign  

SciTech Connect

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.

Chris Hodge

2008-03-01

173

Field profile tailoring in a-Si:H radiation detectors  

SciTech Connect

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.

Fujieda, I.; Cho, G.; Conti, M.; Drewery, J.; Kaplan, S.N.; Perez-Mendez, V.; Quershi, S.; Wildermuth, D. (Lawrence Berkeley Lab., CA (USA)); Street, R.A. (Xerox Palo Alto Research Center, CA (USA))

1990-03-01

174

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

DOEpatents

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.

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

2002-01-01

175

Ion beam induced charge collection (IBICC) studies of cadmium zinc telluride (CZT) radiation detectors  

Microsoft Academic Search

Cadmium zinc telluride (CZT) is an emerging material for room temperature radiation detectors. In order to optimize the performance of these detectors, it is important to determine how the electronic properties of CZT are related to the presence of impurities and defects that are introduced during the crystal growth and detector fabrication. At the Sandia microbeam facility IBICC (ion beam

B. L Doyle; G V??zkelethy; D. S Walsh

2000-01-01

176

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

DOEpatents

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.

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

1996-10-22

177

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

DOEpatents

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.

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

1996-01-01

178

Space radiation dosimetry: An optically stimulated luminescence radiation detector for low-Earth orbit  

Microsoft Academic Search

Scope and method of study. The purpose of this study was to investigate Al2O3:C as a potential optically stimulated luminescence (OSL) radiation detector for Low-Earth Orbit. The OSL response of Al2O3:C was characterized in terms of its luminescence efficiency for a variety of heavy charged particles (HCPs) with features similar to those found in space. The HCP irradiations were performed

Ramona Gaza

2004-01-01

179

Radiation damage of silicon strip detectors in the NA50 experiment  

NASA Astrophysics Data System (ADS)

During operation of the multiplicity detector in the NA50 experiment the single sided AC-coupled p-on-n silicon strip detectors were exposed to charged particle fluences up to 10 14 eq n/cm 2 and ionising doses up to 20 Mrad, with a very non-uniform radiation spatial distribution. Radiation effects in the detectors observed during the '96 lead ion run as well as results of the post-run measurements are presented in this paper.

Alessandro, B.; Beolé, S.; Bonazzola, G.; Crescio, E.; Dabrowski, W.; Giubellino, P.; Grybos, P.; Idzik, M.; Martinetto, M.; Marzari-Chiesa, A.; Masera, M.; Prino, F.; Ramello, L.; Mendes, P. R.; Riccati, L.; Sitta, M.

1998-12-01

180

Wire-chamber radiation detector with discharge control  

DOEpatents

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.

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

1982-03-29

181

Performance of CdZnTe pixellated radiation detectors assembled by a new attachment method  

NASA Astrophysics Data System (ADS)

This paper presented a new carrier board attachment method for pixellated CdZnTe (CZT) radiation detectors by using a special type of anisotropic conductive film (ACF) based on micro-wires. This ACF has very small pitch, high vertical electrical conductivity, and strong mechanical strength. It was found to be suitable for pixellated CZT detector assembly by optimizing detector fabrication processes and attachment conditions. ACF attached detector modules showed excellent spectra responses. Long-term stability and reliability tests on these detectors showed promising results. This ACF attachment technology had been successfully used for pixellated CZT detectors with various physical dimensions and anode pixel patterns.

Lu, Pinghe; Chen, Henry; Awadalla, Salah; Iniewski, Kris; Bindley, Glenn

2010-08-01

182

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

NASA Astrophysics Data System (ADS)

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.

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

2012-08-01

183

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

NASA Astrophysics Data System (ADS)

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

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

184

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

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

185

The effects of large signals on charge collection in radiation detectors: Application to amorphous selenium detectors  

NASA Astrophysics Data System (ADS)

Analytical and numerical models for studying the effects of large signals on charge collection efficiency in radiation detectors are described by considering bimolecular recombination between drifting charge carriers, carrier trapping, and space charge effects. First, an analytical solution is obtained by assuming that the field remains relatively uniform. Then the continuity equations for both holes and electrons, and Poisson's equation across the photoconductor for a short pulse irradiation are simultaneously solved by the finite difference method, without any assumptions. There is a very good agreement between the approximate analytical and numerical solutions for the charge collection efficiency. The numerical results are also compared with Monte Carlo simulations of carrier transport. The charge collection efficiency model is applied to amorphous selenium x-ray image detectors. The bimolecular-recombination-limited charge collection efficiency depends on the total photogenerated carrier density rather than on its spatial distribution. It is found that the recombination plays practically no role up to the total instantaneous carrier generation Q0 of 109 EHPs/cm2 at the applied electric field of 10 V/?m. The effect of recombination on charge collection increases with decreasing applied electric field strength. For high carrier generation (e.g., Q0 of 1012 EHPs/cm2 for an applied field of 10 V/?m), the electric field distributions vary widely across the photoconductor thickness during the travel of charge carriers towards the electrodes. However, the effect of bimolecular recombination on charge collection efficiency is almost independent of bias polarity and the field distribution. The numerical results are also compared with recent experimental data available in the literature.

Kabir, M. Zahangir; Emelianova, E. V.; Arkhipov, V. I.; Yunus, M.; Kasap, S. O.; Adriaenssens, G.

2006-06-01

186

Ion Microbeam Studies of Cadmium Zinc Telluride Radiation Detectors by IBICC  

SciTech Connect

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

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

1998-10-26

187

Radiation induced polarization in CdTe detectors  

Microsoft Academic Search

Polarization induced by irradiation with intense gamma ray sources has been studied in chlorine-compensated CdTe detectors. The influence of several parameters, such as applied field strength, temperature and incident photon flux, on the polarization effect have been investigated. A relationship was found between the degree of polarization, detector efficiency and detector leakage current.

D. Vartsky; M. Goldberg; Y. Eisen; Y. Shamai; R. Dukhan; P. Siffert; J. M. Koebel; R. Regal; J. Gerber

1988-01-01

188

Plasma sprayed alumina coatings for radiation detector development  

NASA Astrophysics Data System (ADS)

Conventional design of radiation detectors uses sintered ceramic insulating modules. The major drawback of these ceramic components is their inherent brittleness. Ion chambers, in which these ceramic spacers are replaced by metallic components with plasma spray coated alumina, have been developed in our Research Centre. These components act as thin spacers that have good mechanical strength as well as high electrical insulation and replace alumina insulators with the same dimensions. As a result, the design of the beam loss monitor ion chamber for CAT could be simplified by coating the outer surface of the HT electrode with alumina. One of the chambers developed for isotope calibrator for brachytherapy gamma sources has its outer aluminium electrode (60 mm dia x 220 mm long) coated with 250 m thick alumina (97%) +titania (3%). In view of potential applications in neutron-sensitive ion chambers used in reactor control instrumentation, studies were carried out on alumina 100m to 500m thick coatings on copper, aluminium and SS components. The electrical insulation varied from 1012 ohms to 108 ohms for coating thicknesses above 200m. The porosity in the coating resulted in some fall in electrical insulation due to moisture absorption. An improvement could be achieved by providing the ceramic surface with moisture-repellent silicone oil coating. Irradiation at Apsara reactor core location showed that the coating on aluminium was found to be unaffected after exposure to 1017 nvt fluence.

Alex, Mary; Balagi, V.; Prasad, K. R.; Sreekumar, K. P.; Ananthapadmanabhan, P. V.

2000-11-01

189

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

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

190

X-Ray Detector: An x-ray radiation detector design code.  

National Technical Information Service (NTIS)

X-Ray Detector (XRD) is an x-ray detector design code. It is intended to aid in the rapid design of x-ray detector packages. The design capabilities of XRD include filters, x-ray mirrors, x-ray diodes, silicon PIN diodes, GaAs PIN diodes, photoconducting ...

R. B. Spielman

1990-01-01

191

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

NASA Technical Reports Server (NTRS)

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.

Weckmann, Stephanie

1997-01-01

192

Thallium bromide optical and radiation detectors for X-ray and gamma-ray spectroscopy  

Microsoft Academic Search

A compound semiconductor, thallium bromide (TlBr), has been investigated as an optical and radiation detector material for use in X- and ?-ray spectroscopy. Single crystals of TlBr have been grown by the traveling molten zone method using zone-purified materials. X- and ?-ray detectors have been fabricated from the TlBr crystals. The TlBr detectors have exhibited good spectrometric performances at room

Keitaro Hitomi; Manabu Matsumoto; Osamu Muroi; Tadayoshi Shoji; Yukio Hiratate

2002-01-01

193

Transport Imaging: Developing an Optical Technique to Characterize Bulk Semiconductor Materials for Next Generation Radiation Detectors.  

National Technical Information Service (NTIS)

Characterization of the mobility-lifetime product is critical to the development of new materials for semiconductor radiation detectors. An optical technique has been developed that allows for the direct determination of the minority carrier diffusion len...

S. L. Catalano

2009-01-01

194

High-energy radiation effects on the ISOPHOT far-infrared detectors  

NASA Astrophysics Data System (ADS)

The performance degradation of far-infrared detectors subjected to gamma-radiation was measured for various operating conditions. Responsivity drifts incompatible with precise photometry were observed. Curing procedures are required for flight operations.

Blum, J.; Hajduk, Ch.; Lemke, D.; Salama, A.; Wolf, J.

195

Liquid radiation detectors based on nanosilver surface plasmon resonance phenomena.  

PubMed

The rapid development of micro- and nanostructures containing silver nanoparticles is based on their unique physical properties. Despite the new applications of silver nanoparticles in nanomedicine are under heavy discussions, silver nanoparticles could be used in liquid radiation detectors thanks to the irradiation-induced surface plasmon resonance (SPR) phenomena observed in the colloidal solutions. Silver nitrate (1 mM AgNO(3)) and sodium citrate (1 wt% and 5 wt% C(6)H(5)O(7)Na(3)) were used as precursors for the fabrication of colloidal solutions. Prepared solutions were exposed to gamma-rays from a (60)Co gamma therapy unit 'Rokus-M' to varying absorbed doses, from 2 to 250 Gy. A UV/VIS/NIR spectrometer (Avantes-2048) was used for the measurement of the optical properties (absorbance) of the silver solutions. It was found that an initial absorbed dose of 2 Gy induced the formation of spherical silver nanoparticles as it was indicated in the absorbance spectrum of the solution, which had a well-pronounced absorption maximum at the wavelength of 410 nm. There is a potential to measure absorbed doses down to around 20 mGy. The SPR peaks at the wavelengths of 500-700 nm were found at the highest investigated doses >100 Gy, indicating the presence of silver nanorods. The colour of colloidal solutions ranged from pale yellow to green and was dependent on the absorbed dose. The investigation has shown that density, size and shape of synthesised silver nanoparticles are dependent on the absorbed dose and that shape transformations of the particles due to irradiation are possible. Application of colloidal solutions containing silver nanoparticles for dosimetric purposes is discussed on the basis of the obtained results. PMID:20159913

Puiso, Judita; Laurikaitiene, Jurgita; Adliene, Diana; Prosycevas, Igoris

2010-01-01

196

Planar antennas for integration with FET-based THz radiation detectors  

Microsoft Academic Search

This paper presents a design of planar antennas integrated with MOSFETs to form a THz radiation detector. The antennas have been developed on thin substrates in order to increase the detector responsivity through eliminating substrate modes responsible for electromagnetic power losses.

Pawel Kopyt

2012-01-01

197

Radiation-detector optical-imaging device is of simplified construction  

NASA Technical Reports Server (NTRS)

A simplified radiation detector was designed which employs an activated continuous front surface consisting of either the diffused or barrier type of semiconducting material with a grid structure on the nonactivated side of the detector. Its form may be either a rectangular coordinate or a polar coordinate system.

1965-01-01

198

Growth and characterization of CdTe single crystals for radiation detectors  

Microsoft Academic Search

To improve the productivity of CdTe radiation detectors, the crystal growth by traveling heater method (THM) as well as the quality of the fabricated detectors were investigated. In the THM growth, optimization of the solvent volume was found to be essential because it affects the shape of the growth interface. The use of the slightly tilted seed from ?111?B was

Minoru Funaki; Tsutomu Ozaki; Kazuyuki Satoh; Ryoichi Ohno

1999-01-01

199

Cadmium telluride gamma-radiation detectors with a high energy resolution  

Microsoft Academic Search

This paper considers the possibility of improving the energy resolution of cadmium telluride gamma-radiation detectors through the choice of the geometry and size of the sensitive region of the detector. The optimum ratio of the product of the mobility and lifetime for electrons to the same product for holes from the point of view of energy resolution is greater than

L. A. Alekseeva; P. G. Dorogov; V. I. Ivanov; A. K. Khusainov

1985-01-01

200

The response of a silicon diode designed for use as a detector for direct solar radiation  

Microsoft Academic Search

A low-cost direct solar radiation detector (DSRD) has been designed, characterized and calibrated. The detector was made of a simple silicon diode and then characterized with respect to spectral response, polar response and environmental stability. It was calibrated by using an Eppley normal incidence pyrheliometer (NIP) mounted on an Eppley power driven sun tracker (ST) whose axis is parallel to

M. A. Macome; J. S. P. Mlatho; M. McPherson

2007-01-01

201

Improved radiation hardness to low-energy protons for oxygenated Si detectors with thermal donors  

NASA Astrophysics Data System (ADS)

Silicon detectors have been made on oxygenated silicon with the incorporation of thermal donors during the oxidation process based on BNL's high-temperature long-time (thermal donor) (HTLT(TD)) technology. The initial doping concentration in HTLT(TD) silicon detectors is twice more than that of standard silicon detectors (same starting material, but no HTLT process), with TD being the dominant donor. Standard and HTLT(TD) silicon detectors have been irradiated by 10 MeV protons up to 2.5×10 14 p/ cm2. It has been found that the increase rate ( ?) of the space charge concentration ( Neff) after space charge sign inversion (SCSI) in HTLT(TD) silicon detectors is about half of that in standard silicon detectors. Further improvement in proton radiation hardness has been observed in terms of the SCSI fluence. The SCSI fluence for HTLT(TD) silicon detectors is more than four times higher than that of standard detectors, although the corresponding ratio of initial space charge concentrations between the two groups of detectors is about two. This result implies that the SCSI is greatly delayed in HTLT(TD) silicon detector compared with silicon detectors with similar initial space charge (all phosphorus) concentration (lower resistivity standard silicon detectors).

Houdayer, A.; Lebel, C.; Leroy, C.; Li, Z.; Verbitskaya, E.

2003-10-01

202

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

203

Dedicated x-ray scintillation detector for digital subtraction angiography using synchrotron radiation  

SciTech Connect

A one-coordinate x-ray detector for digital subtraction angiography using synchrotron radiation is described. It comprises two x-ray-sensitive lines, each having 128 independent channels of scintillation counters. The detector is designed to simultaneously measure the intensities of two linear monochromatic beams being 8--10 mm distant from each other. The spatial resolution of each line ranges from 0.2 to 2 mm. The maximum counting rate is 6 MHz for each channel, and the detection efficiency of the 33.2-keV quanta is close to 100%. Preliminary results of the testing of the detector channels on synchrotron radiation beam are given.

Dementiev, E. N.; Dolbnya, I. P.; Zagorodnikov, E. I.; Kolesnikov, K. A.; Kulipanov, G. N.; Kurylo, S. G.; Medvedko, A. S.; Mezentsev, N. A.; Pindyurin, V. F.; Cheskidov, V. G.; and others

1989-07-01

204

Development of CdZnTe radiation detectors  

NASA Astrophysics Data System (ADS)

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

Bolotnikov, Aleksey; Camarda, Giuseppe; Hossain, Anwar; Kim, Ki Hyun; Yang, Ge; Gul, Rubi; Cui, Yonggang; James, Ralph B.

2011-06-01

205

Cadmium telluride gamma-radiation detectors with a high energy resolution  

SciTech Connect

This paper considers the possibility of improving the energy resolution of cadmium telluride gamma-radiation detectors through the choice of the geometry and size of the sensitive region of the detector. The optimum ratio of the product of the mobility and lifetime for electrons to the same product for holes from the point of view of energy resolution is greater than or equal to 10/sup 2/ for a detector of spherical geometry and should be less than or equal to 10 for a cylindrical geometry and approximately 1 for a planar geometry. The optimum values of the major and minor radii of a spherical detector are calculated.

Alekseeva, L.A.; Dorogov, P.G.; Ivanov, V.I.; Khusainov, A.K.

1985-07-01

206

Recent developments in radiation measurements using nuclear track detectors  

NASA Astrophysics Data System (ADS)

Attempts have been made to use nuclear track detectors in the measurement of neutrons, ?-particles and heavy multi-charged particles. Currently, some of the most important applications include the use of solid-state track detectors in neutron dosimetry, in radon dosimetry in homes and in mines, and charged-particle measurements in space and of accelerator beams used for biomedical applications.In this paper, a review will be given of recent track-detector developments in the fields of neutron and radon measurements.

Hassib, G. M.

1994-07-01

207

Ultimate limits for the radiation hardness of silicon strip detectors for sLHC  

NASA Astrophysics Data System (ADS)

The new SuperLHC upgrade will impose severe restrictions on the radiation hardness of silicon detectors since a maximum fluence of 1016 particles/cm2 is foreseen in the innermost region. Microstrip detectors have been fabricated in p-type high resistivity float zone silicon at CNM facilities, been irradiated at the TRIGA reactor in Ljubljana to a fluence of 1016 neutrons/cm2 and characterized at IFIC laboratory. The total collected charge before and after irradiation in the detectors has been measured by Sr90 beta source and by infrared laser illumination. The results show that even after this extreme radiation fluence, p-type substrate detectors collect 3500 electrons when biased at 800 V, which is enough charge to induce a measurable signal with standard readout electronics. P-type strip detectors could be suitable for the middle and even inner regions of sLHC.

Lozano, M.; Campabadal, F.; García, C.; Gonzalez-Sevilla, S.; Lacasta, C.; Lacuesta, V.; Martí, S.; Miñano, M.; Pellegrini, G.; Ullán, M.; Rafí, J. M.

2007-10-01

208

The effect of oxygen impurities on radiation hardness of FZ silicon detectors for HEP after neutron, proton and gamma irradiation  

Microsoft Academic Search

The radiation hardness for fast neutrons, high energy protons and 60Co gamma rays of planar detectors processed from highly oxygenated silicon detectors obtained by using high temperature (1200°C), long time (> 200 hours) oxidation technology, are compared with standard silicon detectors. For fast neutron irradiation it is found that there is no advantage of using highly oxygenated silicon FZ detectors

B. Dezillie; Z. Li; V. Eremin; W. Chen; L. J. Zhao

2000-01-01

209

The effect of oxygen impurities on radiation hardness of FZ silicon detectors for HEP after neutron, proton and gamma irradiation  

Microsoft Academic Search

Radiation hardness for fast neutrons, high energy protons and 60Co gamma rays of planar detectors processed from highly oxygenated silicon detectors obtained by using the high temperature (1200°C), long time (>200 hours) oxidation technology, are compared with standard silicon detectors. For fast neutron irradiation it is found that there is no advantage of using highly oxygenated silicon FZ detectors as

B. Dezillie; Z. Li; V. Eremin; W. Chen; L. J. Zhao

1999-01-01

210

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

NASA Astrophysics Data System (ADS)

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.

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

2011-10-01

211

Method for mapping charge pulses in semiconductor radiation detectors  

SciTech Connect

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.

Prettyman, T.H.

1998-12-01

212

Low radioactivity material for use in mounting radiation detectors  

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

213

Electronics for a neutron detector and a Geiger-Mueller detector for the radiation protection around MEA and AmPS  

NASA Astrophysics Data System (ADS)

Electronic circuits were developed for the radiation protection set up around the accelerators AmPS (Amsterdam Pulse Stretcher) and MEA. This set up consists of a neutron detector and a Geiger-Mueller detector. The electronics fulfill the requirements of the security service. The amplifier of the neutron detector, the high voltage power supply for the detector, the discriminators, and the power supplies for the electronic circuits are described.

Schipper, J. D.

214

Synchrotron radiation response characterization of coplanar grid CZT detectors  

Microsoft Academic Search

Commercial 15×15×7.5 mm3 coplanar grid CdZnTe detectors were studied on the micron-scale using a collimated high-energy X-ray beam provided by Brookhaven's National Synchrotron Light Source. This powerful tool enables simultaneous studies of detector response uniformity, electronic properties of the material, and effects related to the device's contact pattern and electric field distribution. The availability of a front-end Application Specific Integrated

G. A. Carini; A. E. Bolotnikov; G. S. Camarda; G. W. Wright; G. De Geronimo; D. P. Siddons; R. B. James

2005-01-01

215

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

Microsoft Academic Search

Hydrogenated amorphous silicon and related materials have been applied to radiation detectors, utilizing their good radiation resistance and the feasibility of making deposits over a large area at low cost. Effects of deposition parameters on various material properties of a-Si:H have been studied to produce a material satisfying the requirements for specific detection application. Thick (approx. 50 micron), device quality

Wan-Shick Hong

1995-01-01

216

A program in detector development for the US synchrotron radiation community  

SciTech Connect

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.

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

2001-07-14

217

Multielement silicon detectors for registration of charged particles, x-rays and gamma-radiation  

NASA Astrophysics Data System (ADS)

A novel type multi-sectional detector consisting of separate sections has been developed. Signals from each section pass through a shaping amplifier channel and then are mixed in a special manner. This principle allows reduction of detector's and amplifier's electrical noise in many times, and due to this allows one to develop detectors and spectrometers for various types of radiation with characteristics unreachable at present using traditional methods. For example, it is supposed to obtain energy resolution for alpha-particles 30 keV with active area of the detector 40 cm2. It is possible to create semiconductor spectrometers and radiometers with high resolution and the area of detectors of hundreds of cm2. Possibilities and limitations of this principle had been examined and a series of multi-element detectors and an alpha-spectrometer based on them has been developed. .

Frolov, D. O.; Frolov, O. S.; Sadovnichiy, A. A.; Nimets, O. F.; Shevchenko, V. A.

2001-07-01

218

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

NASA Astrophysics Data System (ADS)

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 evaluated and investigations will be extended to other types of detectors (e.g. LiTaO3 detectors and Golay cells).

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

2009-08-01

219

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

SciTech Connect

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.

Vizkelethy, Gyorgy

2010-07-01

220

Space radiation dosimetry: An optically stimulated luminescence radiation detector for low-Earth orbit  

NASA Astrophysics Data System (ADS)

Scope and method of study. The purpose of this study was to investigate Al2O3:C as a potential optically stimulated luminescence (OSL) radiation detector for Low-Earth Orbit. The OSL response of Al2O3:C was characterized in terms of its luminescence efficiency for a variety of heavy charged particles (HCPs) with features similar to those found in space. The HCP irradiations were performed using the HIMAC accelerator at Chiba (Japan), the proton facility at Loma Linda (CA) and the NSRL facility at Brookhaven (NY). The OSL curves were further investigated to obtain information about the 'mean efficiency' and 'mean LET', parameters that needed to assess the absorbed dose and the dose equivalent. This analysis was applied for simulated mixed radiation fields (ICCHIBAN) and actual space radiation exposures (i.e., STS-105, BRADOS, and TRACER). In parallel, the thermoluminescence response of dosimetry materials LiF:Mg,Ti and CaF2:Tm was also studied. Findings and conclusions. The OSL efficiency of Al2O 3:C exposed to HCPs was found to decrease with increasing linear energy transfer (LET) for the investigated LET range (i.e., from 0.4 keV/mum to 459 keV/mum). For simulated mixed radiation fields with a strong low-LET component, the results indicated that the OSL calibration methods (i.e., tau-method and R-method) can be used with good accuracy to obtain information about the absorbed dose and the dose equivalent. Nevertheless, for mixed fields with a strong high-LET component these methods will give larger errors when estimating the absorbed dose and the dose equivalent. For actual space radiation exposures, the results indicated that different materials/calibration methods (i.e., the LiF:Mg,Ti/HTR-method and the CaF2:Tm/peak 5 + 6/peak 3-method) give different results in terms of 'mean efficiency' and 'mean LET'. This was explained by suggesting that none of the above calibration methods can give information about the true average LET of the incident radiation, but rather about the 'mean LET' weighted by the dosimeter efficiency.

Gaza, Ramona

221

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

PubMed

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

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

2004-01-01

222

Radiation effects on a Ge:Ga photoconductive detector  

NASA Astrophysics Data System (ADS)

Co-60 is the gamma-ray source employed in the present study of the effects of irradiation on a Ge:Ga photoconductive IR detector, at a low photon background level of 4 x 10 to the 8th ph/sq cm per sec which immediately induced NEP-degrading spike noises while gradually increasing responsivity. After cessation of the irradiation, the spikes disappeared but responsivity lingered over several hours. Responsivity change rate is smaller, both before and after the irradiation, for a higher bias voltage. A flashing procedure is used to establish the effectiveness of long term effect cure. The IR detector will be used by the German IR Laboratory.

Oda, N.; Lemke, D.; Wolf, J.

1984-11-01

223

Study of edgeless radiation detector with 3D spatial mapping technique  

NASA Astrophysics Data System (ADS)

Edgeless radiation detector has gained increased attention due to its superiority in the defect-free edge fabrication and the capability to minimize the insensitive area at the detector edge. The doped edge in the edgeless detector is at the same potential with the back plane and causes a local distortion of the electric field at the detector edge. The deformed electric field alters the charge collection of the edge pixel and leads to an inaccurate charge interpolation. To study the influence of active edges on the response of edge pixels, we used an advanced X-ray based 3D spatial mapping technique to visually show the charge collection volumes of pixels. Various edgeless detectors with diverse polarities, thicknesses and edge-to-pixel distances were investigated. For the n-on-p (n+/p?/p+) edgeless detector, the mapping shows that the p-spray isolation method has the advantage of achieving a greater sensitive edge region compared to the p-stop method. And the p-on-p (p+/p?/n+) edgeless detector, reported for the first time, functions for both spatial and energy signals. The n-type edgeless detectors were studied together with a standard Medipix detector with the guard ring design. The results show that the edgeless detector is capable of maximally utilizing the edge region of the detector as the charge sensitive volume, while the standard Medipix detector has still vast insensitive region at the edge. The X-ray spectroscopic measurements with 241Am and 55Fe sources performed on all detectors gives a similar conclusion and proves the 3D spatial mapping results.

Wu, X.; Kalliopuska, J.; Jak?bek, M.; Jak?bek, J.; Gädda, A.; Eränen, S.

2014-04-01

224

High field CdS detector for infrared radiation  

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

225

Radiation detectors and sources enhanced with micro\\/nanotechnology  

Microsoft Academic Search

The ongoing threat of nuclear terrorism presents major challenges to maintaining national security. Currently, only a small percentage of the cargo containers that enter America are searched for fissionable bomb making materials. This work reports on a multi-channel radiation detection platform enabled with nanoparticles that is capable of detecting and discriminating all types of radiation emitted from fissionable bomb making

Chad Michael Whitney

2009-01-01

226

Applications of group II\\/group VI compounds to the design of laser radiation detectors  

Microsoft Academic Search

The article reviews radiation detectors for higher wavelengths and the physics and technology of II\\/VI compounds (Zn, Cd, Hg with Se, Te). The properties of solid solutions (CdTe-HgTe), homogeneous materials, and epitaxial-layer and graded-composition structures are discussed. The advantages of Si photoelectric detectors for work in the near IR and visual spectra, and of CdTe in the X-ray range and

J. Piotrowski; T. Persak; W. Galus

1975-01-01

227

Recovery of radiation damage in CdTe and CdZnTe Detectors  

Microsoft Academic Search

The exposure of CdTe:Cl and Cd0.9Zn0.1Te detectors to increasing doses of ionizing radiation seriously affects their spectroscopic performance. We have investigated the recovery process of the detectors by means of photon (241Am and 57Co) spectroscopy and PICTS (photo-induced current transient spectroscopy) analyses, by studying the evolution with time of their spectroscopic performance and correlating it with the presence of defective

B. Fraboni; A. Cavallini; N. Auricchio; W. Dusi; M. Zanarini; P. Siffert

2004-01-01

228

Radiation pressure induced instabilities in laser interferometric detectors of gravitational waves  

Microsoft Academic Search

The large scale interferometric gravitational wave detectors consist of Fabry-Perot cavities operating at very high powers\\u000a ranging from tens of kW to MW for next generations. The high powers may result in several nonlinear effects which would affect\\u000a the performance of the detector. In this paper, we investigate the effects of radiation pressure, which tend to displace the\\u000a mirrors from

A. Pai; S. V. Dhurandhar; P. Hello; J.-Y. Vinet

2000-01-01

229

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

PubMed

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

Gronchi, Claudia C; Caldas, Linda V E

2013-04-01

230

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

SciTech Connect

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.

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

2010-10-26

231

Detectors  

DOEpatents

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.

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

2002-01-01

232

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

SciTech Connect

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

Wong, J. H. D.; Fuduli, I.; Carolan, M.; Petasecca, M.; Lerch, M. L. F.; Perevertaylo, V. L.; Metcalfe, P.; Rosenfeld, A. B. [Centre for Medical Radiation Physics, University of Wollongong, NSW 2522, Australia and Faculty of Medicine, University of Malaya, Kuala Lumpur 50603 (Malaysia); Centre for Medical Radiation Physics, University of Wollongong, NSW 2522 (Australia); Illawarra Cancer Care Centre, Wollongong Hospital, NSW 2500, Australia and Centre for Medical Radiation Physics, University of Wollongong, NSW 2522 (Australia); Centre for Medical Radiation Physics, University of Wollongong, NSW 2522 (Australia); SPA BIT, Kiev, Ukraine, 04136 (Ukraine); Centre for Medical Radiation Physics, University of Wollongong, NSW 2522 (Australia)

2012-05-15

233

An advanced SiC nuclear radiation detector  

Microsoft Academic Search

This paper reports low noise, high charge collection efficiency, resolution, room temperature, self-biased operation of 3-8 ?m thick, epitaxially grown, SiC Schottky and pn junction diode detectors fabricated on n+ 4H-SiC substrates. These devices are also shown, for the first time, to have a linear gamma ray response. The thin active region used not only eliminates the problems with material

S. Seshadri; A. R. Dulloo; F. H. Ruddy

1997-01-01

234

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

SciTech Connect

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.

Proudfoot, J.

1992-09-01

235

RADIATION HARDNESS / TOLERANCE OF SI SENSORS / DETECTORS FOR NUCLEAR AND HIGH ENERGY PHYSICS EXPERIMENTS.  

SciTech Connect

Silicon sensors, widely used in high energy and nuclear physics experiments, suffer severe radiation damage that leads to degradations in sensor performance. These degradations include significant increases in leakage current, bulk resistivity, and space charge concentration. The increase in space charge concentration is particularly damaging since it can significantly increase the sensor full depletion voltage, causing either breakdown if operated at high biases or charge collection loss if operated at lower biases than full depletion. Several strategies can be used to make Si detectors more radiation had tolerant to particle radiations. In this paper, the main radiation induced degradations in Si detectors will be reviewed. The details and specifics of the new engineering strategies: material/impurity/defect engineering (MIDE); device structure engineering (DSE); and device operational mode engineering (DOME) will be given.

LI,Z.

2002-09-09

236

Radiation induced thermoluminescence in CaF 2:Tm detectors  

NASA Astrophysics Data System (ADS)

The fact that in CaF 2:Tm, thermoluminescence (TL) glow peaks occuring at different temperatures have different sensitivities to low and high LET radiations, has been found useful for the simultaneous and separate determination of fast neutron and gamma ray absorbed doses from therapeutically used neutron beams. The gamma ray and fast neutron responses of the individual glow peaks are found to be additive for separate and successive irradiations. A glow peak at 150° C which has a relatively smaller sensitivity to densely ionizing radiations, exhibit reduced sensitivity to high doses of even low LET radiations ( 60Co gamma rays). On heat treatment, the relative TL responses of 110, 150 and 240°C glow peaks are found to reduce in different proportions. In view of the present study, the various explanations for the difference in LET dependences of the glow peaks have been analysed.

Pradhan, A. S.; Rassow, J.

1987-03-01

237

Development of Radiation Detectors Based on Hydrogenated Amorphous Silicon and its Alloys  

Microsoft Academic Search

Hydrogenated amorphous silicon and related materials have been applied to radiation detectors, utilizing their good radiation resistance and the feasibility of making deposits over a large area at low cost. Effects of deposition parameters on various material properties of a-Si:H have been studied to produce a material satisfying the requirements for specific detection application. Thick(~50 mu m), device quality a-Si:H

Wan-Schick Hong; Wan-Shick

1995-01-01

238

BRIEF COMMUNICATIONS: Recording of thermal radiation by a detector with double frequency conversion  

Microsoft Academic Search

A discussion is given of the recording of thermal radiation by means of two-stage frequency conversion in AgGaS2 and alpha-HIO3 crystals. It is shown that the sensitivity of a detector of this kind is limited by the thermal noise of the nonlinear crystal in the first stage and by the background radiation. At room temperature the contribution of the thermal

É. S. Voronin; A. A. Popesku; Vladimir S. Solomatin; Vladimir V. Shuvalov; S. A. Pleshanov

1978-01-01

239

HTLT oxygenated silicon detectors: radiation hardness and long-term stability  

NASA Astrophysics Data System (ADS)

Silicon detectors fabricated by BNLs high-temperature, long time (HTLT) oxidation technology have been characterized using various techniques for material/detector properties and radiation hardness with respect to gamma, proton and neutron irradiation. It has been found that a uniform oxygen distribution with a concentration of 4×10 17/cm 3 has been achieved in high-resistivity FZ silicon with our HTLT technology. With the standard HTLT technology, the original high resistivity of FZ silicon will be retained. However, the controlled introduction of thermal donors (TD) with a concentration higher than the original shallow doping impurity can be achieved with a process slightly altered from the standard HTLT technology (HTLT-TD). Detectors made by both technologies (HTLT and HTLT-TD) have been found to be advantageous in radiation hardness to gamma and proton irradiation, in terms of detector full depletion voltage degradation, as compared to the control samples. In fact, these detectors are insensitive to gamma irradiation up to 600 Mrad and more tolerant by at least a factor of two to proton irradiation and the following reverse annealing. However, there is little improvement in radiation hardness to neutron irradiation, which has been attributed to the nature of neutron-induced damage that is dominated by extended defects or defect clusters. Microscopic measurements (I-DLTS) have also been made on control and HTLT samples and will be compared and presented.

Li, Z.; Dezillie, B.; Bruzzi, M.; Chen, W.; Eremin, V.; Verbitskaya, E.; Weilhammer, P.

2001-04-01

240

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

DOEpatents

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.

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

1989-01-01

241

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

DOEpatents

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.

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

1987-02-27

242

Spectral and temperature correction of silicon photovoltaic solar radiation detectors  

Microsoft Academic Search

Silicon photovoltaic sensors are an inexpensive alternative to standard thermopile sensors for the measurement of solar radiation. However, their temperature and spectral response render them less accurate for global horizontal irradiance and unsuitable for direct beam and diffuse horizontal irradiance unless they can be reliably corrected. A correction procedure for the rotating shadowband radiometer, which measures all three components, based

J. J. Michalsky; R. Perez; L. Harrison; B. A. LeBaron

1991-01-01

243

Applications of a-Si:H Radiation Detectors.  

National Technical Information Service (NTIS)

Device structures and operation principles are described for detecting various kinds of radiation with hydrogenated amorphous silicon (a-Si:H) layers. With some new configurations such as the buried p-i-n structure and the use of interdigitated electrodes...

I. Fujieda G. Cho M. Conti J. Drewery S. N. Kaplan

1989-01-01

244

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

SciTech Connect

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

Ivanov, A. M., E-mail: Alexandr.Ivanov@mail.ioffe.ru; Sadokhin, A. V.; Strokan, N. B.; Lebedev, A. A. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation)

2011-10-15

245

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

NASA Astrophysics Data System (ADS)

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/?m), 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.

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

2012-07-01

246

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

SciTech Connect

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.

,

2012-10-01

247

Preliminary results from an investigation into nanostructured nuclear radiation detectors for non-proliferation applications  

NASA Astrophysics Data System (ADS)

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.

Guss, Paul; Guise, Ronald; Yuan, Ding; Mukhopadhyay, Sanjoy

2012-10-01

248

Detector-receiver of millimeter and submillimeter wave radiation constructed on the basis of a superconducting point contact  

Microsoft Academic Search

The paper describes the design of a broadband detector of millimeter and submillimeter wave radiation on the basis of a superconducting point contact. The device consists of a helium cryostat, a system for input of radiation with a modulator, a detector head with the superconducting point contact, and an electronic circuit ensuring control of the volt-ampere characteristics and recording of

Iu. Ia. Divin; A. I. Zhukov; F. Ia. Nad; K. A. Rulev; S. Iu. Turygin

1976-01-01

249

Background and radiation resistance tests of neutral particle analyzer detectors for ITER by using a fast neutron beam  

NASA Astrophysics Data System (ADS)

The radiation resistance and background sensitivity of scintillation (Hamamatsu H8500D photo-multiplier) and semiconductor (ORTEC BF-018-100-60 and BU-012-050-100) detectors to neutron and gamma radiation were investigated. Conclusions are drawn concerning the possibility of using such detectors in neutral particle analyzers that are being developed for ITER at the Ioffe Institute.

Afanasyev, V. I.; Kozlovskii, S. S.; Makar'in, D. V.; Mel'Nik, A. D.; Mironov, M. I.; Nesenevich, V. G.; Petrov, M. P.; Petrov, S. Ya.; Chernyshev, F. V.

2010-05-01

250

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

Microsoft Academic Search

Large-volume cadmium zinc telluride (CZT) radiation detectors would greatly improve radiation detection capabilities and, therefore, attract extensive scientific and commercial interests. CZT crystals with volumes as large as hundreds of centimeters can be achieved today due to improvements in the crystal growth technology. However, the poor performance of large-volume CZT detectors is still a challenging problem affecting the commercialization of

G. Yang; A. E. Bolotnikov; G. S. Camarda; Y. Cui; A. Hossain; H. W. Yao; K. Kim

2009-01-01

251

Radiation detectors and sources enhanced with micro/nanotechnology  

NASA Astrophysics Data System (ADS)

The ongoing threat of nuclear terrorism presents major challenges to maintaining national security. Currently, only a small percentage of the cargo containers that enter America are searched for fissionable bomb making materials. This work reports on a multi-channel radiation detection platform enabled with nanoparticles that is capable of detecting and discriminating all types of radiation emitted from fissionable bomb making materials. Typical Geiger counters are limited to detecting only beta and gamma radiation. The micro-Geiger counter reported here detects all species of radiation including beta particles, gamma/X-rays, alpha particles, and neutrons. The multi-species detecting micro-Geiger counter contains a hermetically sealed and electrically biased fill gas. Impinging radiation interacts with tailored nanoparticles to release secondary charged particles that ionize the fill gas. The ionized particles collect on respectively biased electrodes resulting in a characteristic electrical pulse. Pulse height spectroscopy and radiation energy binning techniques can then be used to analyze the pulses to determine the specific radiation isotope. The ideal voltage range of operation for energy discrimination was found to be in the proportional region at 1000VDC. In this region, specific pulse heights for different radiation species resulted. The amplification region strength which determines the device sensitivity to radiation energy can be tuned with the electrode separation distance. Considerable improvements in count rates were achieved by using the charge conversion nanoparticles with the highest cross sections for particular radiation species. The addition of tungsten nanoparticles to the microGeiger counter enabled the device to be four times more efficient at detecting low level beta particles with a dose rate of 3.2uR/hr (micro-Roentgen per hour) and just under three times more efficient than an off the shelf Geiger counter. The addition of lead nanoparticles enabled the gamma/X-ray microGeiger counter channel to be 28 times more efficient at detecting low level gamma rays with a dose rate of 10uR/hr when compared to a device without nanoparticles. The addition of 10B nanoparticles enabled the neutron microGeiger counter channel to be 17 times more efficient at detecting neutrons. The device achieved a neutron count rate of 9,866 counts per minute when compared to a BF3 tube which resulted in a count rate of 9,000 counts per minute. By using a novel micro-injection ceramic molding and low temperature (950°C) silver paste metallizing process, the batch fabrication of essentially disposable micro-devices can be achieved. This novel fabrication technique was then applied to a MEMS neutron gun and water spectroscopy device that also utilizes the high voltage/temperature insulating packaging.

Whitney, Chad Michael

252

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

DOEpatents

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

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

2003-03-04

253

Radiation detectors based on 4H semi-insulating silicon carbide  

NASA Astrophysics Data System (ADS)

In this work, radiation detectors were fabricated using 8 mm × 8 mm substrates, ~ 390 ?m in thickness, diced from commercial (0001) 4H-SiC semi-insulating wafer (> 109 Ohm-cm). Our characterization results, including x-ray diffraction (XRD), electron beam induced current (EBIC), chemical etching, cross-polarized imaging, thermally stimulated current (TSC) measurements, chemical etching and Raman spectroscopy, show the high quality of the semiinsulating SiC crystals, which are believed to meet the requirements of fabricating high performance radiation detectors. Current-voltage characteristics showed very low leakage current (~ 1.5 pA at -500 V) and the capability of detector's operation up to 200°C.

Mandal, Krishna C.; Krishna, Ramesh; Muzykov, Peter G.; Laney, Zegilor; Das, Sandip; Sudarshan, Tangali S.

2010-08-01

254

Computational Models for Crystal Growth of Radiation Detector Materials: Growth of CZT by the EDG Method  

SciTech Connect

Crystals are the central materials element of most gamma radiation detection systems, yet there remains surprisingly little fundamental understanding about how these crystals grow, how growth conditions affect crystal properties, and, ultimately, how detector performance is affected. Without this understanding, the prospect for significant materials improvement, i.e., growing larger crystals with superior quality and at a lower cost, remains a difficult and expensive exercise involving exhaustive trial-and-error experimentation in the laboratory. Thus, the overall goal of this research is to develop and apply computational modeling to better understand the processes used to grow bulk crystals employed in radiation detectors. Specifically, the work discussed here aims at understanding the growth of cadmium zinc telluride (CZT), a material of long interest to the detector community. We consider the growth of CZT via gradient freeze processes in electrodynamic multi-zone furnaces and show how crucible mounting and design are predicted to affect conditions for crystal growth. (authors)

Derby, Jeffrey J.; Gasperino, David [Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455-0132 (United States)

2008-07-01

255

Silicon field-effect transistors as radiation detectors for the Sub-THz range  

SciTech Connect

The nonresonance response of silicon metal-oxide-semiconductor field-effect transistors (Si-MOSFETs) with a long channel (1-20 {mu}m) to radiation in the frequency range 43-135 GHz is studied. The transistors are fabricated by the standard CMOS technology with 1-{mu}m design rules. The volt-watt sensitivity and the noise equivalent power (NEP) for such detectors are estimated with the calculated effective area of the detecting element taken into account. It is shown that such transistors can operate at room temperature as broadband direct detectors of sub-THz radiation. In the 4-5 mm range of wavelengths, the volt-watt sensitivity can be as high as tens of kV/W and the NEP can amount to 10{sup -11} - 10{sup -12}W/{radical}Hz . The parameters of detectors under study can be improved by the optimization of planar antennas.

But, D. B., E-mail: but.dmitry@gmail.com; Golenkov, O. G.; Sakhno, N. V.; Sizov, F. F.; Korinets, S. V.; Gumenjuk-Sichevska, J. V.; Reva, V. P.; Bunchuk, S. G. [National Academy of Sciences of Ukraine, Lashkaryov Institute of Semiconductor Physics (Ukraine)

2012-05-15

256

A nanocrystalline CVD diamond film as an x-ray radiation detector  

NASA Astrophysics Data System (ADS)

In this work, an x-ray radiation detector was developed from a nanocrystalline diamond (NCD) film. The NCD film, with a grain size of about 20 nm and a thickness of ~5 µm, was deposited on a silicon substrate using a hot-filament chemical vapour deposition (HFCVD) method. The response to radiation and the energy resolution at room temperature of the obtained metal-NCD/Si-metal detector were investigated using 5.9 keV x-rays from a 55Fe source. With an electric field 50 kV cm-1, this detector showed a dark-current of ~5.88 µA, and under x-ray illumination a net response current of ~576 nA and an energy resolution of ~22.7%. It was also shown that the energy resolution deteriorated when the diamond grain size was reduced.

Wang, Linjun; Liu, Jianmin; Xu, Run; Peng, Hongyan; Shi, Weimin; Xia, Yiben

2007-02-01

257

Tests of the radiation hardness of silicon strip detectors under neutron, proton, and gamma irradiation  

Microsoft Academic Search

Summary form only given, as follows. As part of a program to develop silicon central tracking systems for the next generation of high-energy, high-luminosity accelerators such as the Superconducting Super Collider and the Relativistic Heavy Ion Collider, the effects of radiation damage in silicon detectors are being studied in detail. Results on neutron and proton irradiations at Los Alamos National

H. J. Ziock; J. G. Boissevain; K. Holzscheiter; J. S. Kapustinsky; W. W. Kinnison; D. M. Lee; W. C. Sailor; W. F. Sommer; W. E. Sondheim; R. S. Wagner; N. Cartiglia; J. DeWitt; D. Dorfan; B. Hubbard; J. Leslie; K. F. O'Shaughnessy; D. Pitzl; W. A. Rowe; H. F.-W. Sadrozinski; A. Seiden; E. Spencer; J. A. Ellison; S. Jerger; D. Joyce; C. Lietzke; S. Wimpenny; P. Ferguson; J. A. J. Matthews; D. Skinner

1991-01-01

258

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

National Technical Information Service (NTIS)

Epitaxial grown thick layers (>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...

Z. Li V. Eremin I. Ilyashenko A. Ivanov E. Verbitskaya

1997-01-01

259

Role of Oxygen and Carbon Impurities in the Radiation Resistance of Silicon Detectors  

Microsoft Academic Search

The influence of oxygen and carbon impurities on the concentrations of defects in silicon for detector uses, in complex fields of radiation (proton cosmic field at low orbits around the Earth, at Large Hadron Collider and at the next generation of accelerators as Super-LHC) is investigated in the frame of the quantitative model developed previously by the authors. The generation

Sorina Lazanu; Ionel Lazanu

2003-01-01

260

Investigations on radiation hardness of DEPFET sensors for the Belle II detector  

NASA Astrophysics Data System (ADS)

In the upgrade of the Belle detector at KEK (Tsukuba, Japan) the two innermost layers of the vertex detector will be realized by a pixel detector (PXD) consisting of DEPFET (DEpleted P-channel Field Effect Transistor) matrices. As the position of the detector will be very close to the beam pipe, it will suffer from intense radiation levels. The main radiation background is the luminosity related 4-fermion final state radiation, which damages the silicon bulk material and the silicon dioxide from the gate contacts. With the dose expected at Belle II, the DEPFET suffers mainly from additional leakage current and increase in noise. In addition, defects in the silicon dioxide change transistor parameters, e.g. the threshold voltage. We will show results on the hardness factor of electrons after a 10 MeV electron irradiation which was performed in the dose and energy range relevant for the PXD. In addition, we present X-ray irradiations of DEPFET equivalent test structures and compare radiation hardness for different oxide parameters in the prototype production.

Ritter, Andreas; Andricek, Ladislav; Kleinohl, Tobias; Koffmane, Christian; Lütticke, Florian; Marinas, Carlos; Moser, Hans-Günther; Ninkovic, Jelena; Richter, Rainer; Schaller, Gerhard; Schnecke, Martina; Schopper, Florian

2013-12-01

261

Study of a New Process for Fabrication on Thin de/DX Nuclear Radiation Detectors.  

National Technical Information Service (NTIS)

Research on a new process for fabrication of thin nuclear radiation detectors with dE/dx energy loss, used specifically for the identification of charged particles is described. The new process for fabrication of these dE/dX diodes consists in dissolving,...

A. Tetefort

1977-01-01

262

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

ERIC Educational Resources Information Center

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…

Consumer Dynamics Inc., Rockville, MD.

263

Evaluation of Semiinsulating Annealed InP:Ta for Radiation Detectors  

Microsoft Academic Search

InP crystals were grown by the Czochralski technique. They were purified by inclusion of Ta into the growth melt and then converted to the semiinsulating state by annealing. Various annealing regimes were examined to find the optimum material for radiation detectors. Temperature dependent Hall measurements were carried over the range from 300 to 430 K and the activation energy of

Karel Zdansky; Vladyslav Gorodynskyy; Ladislav Pekarek; Halyna Kozak

2006-01-01

264

Performance enhancements of compound semiconductor radiation detectors using digital pulse processing techniques  

Microsoft Academic Search

The potential benefits of using compound semiconductors for X-ray and gamma ray spectroscopy are already well known. Radiation detectors based on high atomic number and wide band gap compound semiconductors show high detection efficiency and good spectroscopic performance even at room temperature. Despite these appealing properties, incomplete charge collection is a critical issue. Generally, incomplete charge collection, mainly due to

L. Abbene; G. Gerardi

2011-01-01

265

Model for Estimating Directional Flux and Detector Response for Space Radiation Experiments  

Microsoft Academic Search

We describe a model for estimating the count rate, geometric factor, and gathering power for a particle telescope in an anisotropic space particle radiation field. The model can be used to estimate the response of many detector designs, in particular their sensitivity to anisotropy in the ambient field. The model is implemented within a comprehensive tool for modeling space environment

Stuart L. Huston; David Cantwell; Paul Dorman; John Carsten

2007-01-01

266

A comparison study on three different radiation detectors used for liquid levelmetry.  

PubMed

In this paper, three different radiation detectors (BF3 counter, NE213 and BGO scintillators) and an (241)Am-Be isotopic neutron-gamma source have been used for a typical liquid levelmetry. The study shows that the use of the Am-Be source together with an NE213 scintillator has the best performance. PMID:23520202

Ghorbani, P; Bayat, E; Ghal-Eh, N

2013-01-01

267

Performance of the Transition Radiation Detector of the PAMELA space mission  

Microsoft Academic Search

The performance of the Transition Radiation Detector (TRD) of the PAMELA telescope has been studied using beam test data and simulation tools. PAMELA is a satellite—borne magnetic spectrometer designed to measure particles and antiparticles spectra in cosmic rays. The particle identification at high energy will be achieved by combining the measurements by the TRD and a silicon—tungsten imaging calorimeter. The

M. Ambriola

2002-01-01

268

From HEP to medical radiation dosimetry – The silicon strip detector dose magnifying glass  

Microsoft Academic Search

High energy physics (HEP) experiments and research gave rise to the development of high spatial resolution tracking vertex detectors and the accompanying data acquisition systems (DAQ) capable of high temporal resolution measurements. The technology translation from HEP to the day to day medical radiation dosimetry is gradual but certain. This paper discusses the design and development of a high spatial

J. H. D. Wong; D. Cutajar; M. L. F. Lerch; M. Petasecca; T. Knittel; M. Carolan; V. L. Perevertaylo; P. Metcalfe; A. B. Rosenfeld

269

EFFECT OF SURFACE PREPARATION TECHNIQUE ON THE RADIATION DETECTOR PERFORMANCEOF CDZNTE  

SciTech Connect

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.

Duff, M

2007-05-23

270

Radiation effects in polymers for plastic scintillation detectors  

SciTech Connect

Radiation damage studies were performed on polystyrene and poly(vinyltoluene) samples containing different concentrations of either an antioxidant (A O-2) or a plasticizer (PP-4). In addition, parallel studies were carried out utilizing samples of these polymers prepared in the presence of cross-linking agents such as NPG, HDA, and DVB. The samples were irradiated using a {sup 60} Co source to total doses of 1 and 10 Mrad, at a dose rate of approximately 1 Mrad/h. Transmittance measurements were recorded before and immediately after irradiation, and after oxygen annealing. These experiments showed that none of these agents improved the radiation resistance of polystyrene and poly(vinyltoluene) with regard to their optical properties.

Pla-Dalmau, A.; Bross, A.D. [Fermi National Accelerator Lab., Batavia, IL (United States); Hurlbut, C.R.; Moser, S.W. [Bicron Corp., Newbury, OH (United States)

1994-04-20

271

Digital configurable instrument for emulation of signals from radiation detectors  

NASA Astrophysics Data System (ADS)

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.

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

2014-01-01

272

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

NASA Astrophysics Data System (ADS)

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.

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

273

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

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.

Knoll, G.F.

1995-11-01

274

Intravascular radiation detectors for the detection of vulnerable atheroma.  

PubMed

An intravascular catheter was developed to identify inflammation in coronary atheroma. Inflammation in atheroma is associated with large numbers of macrophages. These cells have increased metabolism, increased expression of chemotactic receptors, and a high frequency of apoptosis-associated phosphatidylserine expression. Each of these parameters can be identified in vivo using specific radiolabeled agents: metabolism can be identified with 18F fluorodeoxyglucose (FDG), receptor expression with 99mTc monocyte chemotactic peptide-1, and apoptosis with 99mTc annexin V. The locally increased concentration of these tracers is readily demonstrable in experimental lesions by ex vivo autoradiography; however, the small lesion size makes it difficult to identify atheroma in the coronaries with conventional imaging equipment. In contrast, with a radiation-sensitive catheter, optimized to sense charged particle rather than gamma or x-radiation, specific lesions could be identified and localized. Charged particle radiation is emitted as a byproduct of nearly all radioactive decay but is typically most abundant in radionuclides that decay by beta emission (either positrons or negatrons). Prototype catheters, using a plastic scintillator mated to an optical fiber, have been tested in the laboratory with the positron-emitting radiopharmaceutical 18FDG. The catheter had sufficient sensitivity to detect lesions concentrating nanocurie concentrations of 18FDG. Ex vivo experiments in apo-e-/- mice confirmed the ability of the catheter to detect 18FDG in aortic lesions. These feasibility studies demonstrate the sensitivity of a beta-sensitive catheter system. Additional mechanical refinements are needed to optimize the system in anticipation of in vivo animal studies. PMID:16631517

Strauss, H William; Mari, Carina; Patt, Bradley E; Ghazarossian, Vartan

2006-04-18

275

Evaluation of high density DRAMs as a nuclear radiation detector.  

PubMed

The research is based on the nuclear radiation induced soft error phenomenon associated with dynamic random access memory devices (DRAMs). Samples of 256 kbit and 1 Mbit decapped DRAMs from several manufactures were exposed to standard alpha sources and showed a linear response with an intrinsic detection efficiency approaching 10%. Sensitivity studies were performed to evaluate the effects of DRAM operating voltage, refresh frequency and the data pattern stored prior to irradiation. The associated mechanism of soft error phenomenon is discussed. Samples were also exposed to gamma rays up to 10(5) rad to examine the total dose effect. The annealing phenomenon after gamma exposure is also presented. PMID:9463880

Chou, H P; Chou, T C; Hau, T H

1997-01-01

276

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

PubMed

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(2)SiO(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. PMID:22128972

Yamamoto, Seiichi; Hatazawa, Jun

2011-11-01

277

Spectral correction of silicon photodiode solar radiation detectors  

SciTech Connect

The multi-filter rotating shadowband radiometer (MFRSR) is a ground- based instrument that uses a silicon photodiode sensor to measure shortwave global and diffuse horizontal irradiance from which direct normal irradiance is calculated. Besides this multiplexing advantage, silicon sensors are rugged, stable and have a fast time response. On the other hand, silicon sensors are both thermally and spectrally sensitive. They, as do all pyranometric sensors, have an imperfect cosine response, especially at high solar-zenith angles. In the MFRSR two of these problems are solved. The MFRSR`s cosine response is measured and corrected. An automatic heater maintains the MFRSR detector at a constant temperature near 40 {degree}C. This paper describes a correction scheme, based on sky conditions, to account for the remaining spectral bias. The data base for these corrections was collected in Albany, New York, during 1993. The MFRSR and WMO firstclass thermopile instruments were sampled every 15 seconds and 5- minute averages were compared. The differences in time response between silicon and thermopile instruments contributes substantially to the remaining root-mean-square error reported.

Zhou, C.; Michalsky, J.

1994-12-31

278

Wide bandgap semiconductor detectors for harsh radiation environments  

NASA Astrophysics Data System (ADS)

In this work two wide bandgap materials, silicon carbide (SiC) and gallium nitride (GaN), were investigated for their performance in harsh radiation environments. Schottky devices were fabricated on vanadium doped SiC (V-SiC), Okmetic semi insulating (SI) non-vanadium doped SiC, SI GaN grown by MOCVD (metal organic chemical vapour deposition) and bulk GaN. Completed devices were electrically characterised and the CCE (charge collection efficiency) calculated from pulse height spectra of 241Am ? particles. SI GaN samples were irradiated with estimated neutron fluences of up to 1016 n/cm2 (Ljubljana), proton fluences of 1016 p/cm2 (CERN), and a dose of 600 Mrad of 10 keV X-rays (ICSTM, London). V-SiC samples were irradiated up to 5×1014 ?/cm2 using 300 MeV/c pions (PSI). Electrical characterisation and CCE calculations were repeated after irradiation to observe changes in properties caused by radiation induced damage.

Grant, J.; Cunningham, W.; Blue, A.; O'Shea, V.; Vaitkus, J.; Gaubas, E.; Rahman, M.

2005-07-01

279

Investigation of radiation damage in the SLD CCD vertex detector 2003 IEEE nuclear science symposium, medical imaging conference, and workshop of room-temperature semiconductor detectors  

Microsoft Academic Search

Early in the operation of the SLD CCD vertex detector (VXD3) at the SLC, radiation damage to the CCDs was observed. It is well known that low energy light particles (electrons and photons) are a few orders of magnitude less effective than heavy particles (neutrons or heavy charged particles) in the generation of radiation damage effects in silicon. The SLD

James E. Brau; Olga B. Igonkina; Chris T. Potter; Nikolai B. Sinev

2003-01-01

280

Effects of Te inclusions on the performance of CdZnTe radiation detectors  

SciTech Connect

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.

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

281

CdZnTe semiconductor parallel strip Frisch grid radiation detectors  

SciTech Connect

CdZnTe wide band gap compound semiconducting material offers promise as a room temperature operated gamma ray spectrometer. Position-dependent free charge carrier losses during transport can prevent efficient charge carrier extraction from semiconductor detectors and severely reduce energy resolution. Hole trapping losses in CdZnTe radiation detectors are far worse than electron trapping losses and resolution degradation in CdZnTe detectors results primarily from severe hole trapping during transport. Coplanar radiation detectors improved energy resolution by sensing the induced charge primarily from the motion of electrons. Demonstrated is an alternative approach to single free charge carrier sensing, in which a parallel strip Frisch grid is fabricated on either side of a parallelepiped block. The detectors are three terminal devices, but require only one preamplifier for the output signal. The prototype devices demonstrate a considerable increase in energy resolution when operated in the true Frisch grid mode rather than the planar mode, with a demonstrated room temperature energy resolution for 662 keV gamma rays of 5.91 % at FWHM for a 10 mm x 2 mm x 10 mm device. Presently, high surface leakage currents prevent large voltages from being applied to the devices, which ultimately reduces their maximum achievable energy resolution. Further improvements are expected with the realization of reduced surface leakage currents.

McGregor, D.S.; He, Z.; Seifert, H.A.; Wehe, D.K. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering and Radiological Sciences] [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering and Radiological Sciences; Rojeski, R.A. [Etec Systems, Inc., Hayward, CA (United States)] [Etec Systems, Inc., Hayward, CA (United States)

1998-06-01

282

Towards above-ground antineutrino detectors for cooperative monitoring : background radiation studies.  

SciTech Connect

We describe an assembly of detectors that quantifies the background radiation present at potential above ground antineutrino detector development and deployment sites. Antineutrino detectors show great promise for safeguard applications in directly detecting the total fission rate as well as the change in fissile content of nuclear power reactors. One major technical challenge that this safeguard application must overcome is the ability to distinguish signals from antineutrinos originating in the reactor core from noise due to background radiation created by terrestrial and cosmogenic sources. To date, existing detectors increase their ability to distinguish antineutrino signals by being surrounded with significant shielding and being placed underground. For the safeguard's agency, this is less than optimal, increasing the overall size and limiting the placement of this system. For antineutrino monitoring to be a widely deployable solution, we must understand the backgrounds found above ground at nuclear power plants that can mimic the antineutrino signal so that these backgrounds can be easily identified, separated, and subtracted rather than shielded. The design, construction, calibration, and results from the deployment of these background detectors at a variety of sites will be presented.

Sadler, Lorraine E.

2008-10-01

283

Simultaneous measurement of neutron and gamma-ray radiation levels from a TRIGA reactor core using silicon carbide semiconductor detectors  

Microsoft Academic Search

The ability of a silicon carbide radiation detector to measure neutron and gamma radiation levels in a TRIGA reactor's mixed neutron\\/gamma field was demonstrated. Linear responses to epicadmium neutron fluence rate (up to 3×107 cm-2 s-1) and to gamma dose rate (0.6-234 krad-Si h-1) were obtained with the detector. Axial profiles of the reactor core's neutron and gamma-ray radiation levels

A. R. Dulloo; F. H. Ruddy; J. G. Seidel; C. Davison; T. Flinchbaugh; T. Daubenspeck

1999-01-01

284

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

SciTech Connect

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

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

2011-08-07

285

Gated fiber-optic-coupled detector for in vivo real-time radiation dosimetry.  

PubMed

Gated detection of the output of a fiber-optic-coupled radiation dosimeter effectively eliminated the direct contribution of Cerenkov radiation to the signal. The radiation source was an external beam radiotherapy machine that provided pulses of 6-MeV x rays. Gated detection was used to discriminate the signal collected during the radiation pulses, including Cerenkov interference, from the signal collected between the radiation pulses due only to phosphorescence from the Cu(1+)-doped glass detector. Gated detection of the long-lived phosphorescence of the Cu(1+)-doped glass provided real-time dose measurements that were linear with the absorbed dose and that were accurate for all field sizes studied. PMID:15046169

Justus, Brian L; Falkenstein, Paul; Huston, Alan L; Plazas, Maria C; Ning, Holly; Miller, Robert W

2004-03-10

286

Spectral and temperature correction of silicon photovoltaic solar radiation detectors  

SciTech Connect

Silicon photovoltaic sensors are an inexpensive alternative to standard thermopile sensors for the measurement of solar radiation. However, their temperature and spectral response render them less accurate for global horizontal irradiance and unsuitable for direct beam and diffuse horizontal irradiance unless they can be reliably corrected. A correction procedure for the rotating shadowband radiometer, which measures all three components, based on a three-way parameterization of the solar position and sky conditions is proposed. After correction, root-mean-square errors for the global and diffuse horizontal irradiance and the direct normal irradiance are about 10, 12, and 13 W/m{sup 2} in comparison with coincident, 5-minute thermopile measurements. While the numerical results are specific to the rotating shadowband instrument, the correction algorithm should apply universally.

Michalsky, J.J.; Perez, R.; Harrison, L. (State Univ. of New York, Albany (United States)); LeBaron, B.A. (Pacific Northwest Lab., Richland, WA (United States))

1991-01-01

287

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

SciTech Connect

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.

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

288

Radiation Background Study for Beam Monitoring Detector of Hall C Beam Line at Jefferson Lab  

NASA Astrophysics Data System (ADS)

Beams of high energy electrons are used to conduct nuclear physics experiments at Thomas Jefferson National Accelerator Facility (TJNAF). Sufficient information about the beam profile and momentum distribution is necessary for most experiments. For on-line measurement of the beam profile and energy, a non-destructive beam profile monitor detector, based on residual gas ionization and utilizing microchannel plate technology, is being prototyped to be used in the Hall C beam line. A GEANT Monte Carlo simulation used to study the radiation background on the detector and the beam line will be discussed.

Beedoe, Shelton; Danagoulian, Samuel; Sawafta, Reyad; Carlini, Roger; Yan, Chen

1997-08-01

289

Application of different TL detectors for the photon dosimetry in mixed radiation fields used for BNCT.  

PubMed

Different approaches for the measurement of a relatively small gamma dose in strong fields of thermal and epithermal neutrons as used for Boron Neutron Capture Therapy (BNCT) have been studied with various thermoluminescence detectors (TLDs). CaF(2):Tm detectors are insensitive to thermal neutrons but not tissue-equivalent. A disadvantage of applying tissue-equivalent (7)LiF detectors is a strong neutron signal resulting from the unavoidable presence of (6)Li traces. To overcome this problem it is usual to apply pairs of LiF detectors with different (6)Li content. The experimental determination of the thermal neutron response ratio of such a pair at the Geesthacht Neutron Facility (GeNF) operated by PTB enables measurement of the photon dose. In the experimental mixed field of thermal neutrons and photons of the TRIGA reactor at Mainz the photon dose measured with different types of (7)LiF/(nat)LiF TLD pairs agree within a standard uncertainty of 6% whereas the CaF(2):Tm detectors exhibit a photon dose by more than a factor of 2 higher. It is proposed to determine suitable photon energy correction factors for CaF(2):Tm detectors with the help of the (7)LiF/(nat)LiF TLD pairs in the radiation field of interest. PMID:16644976

Burgkhardt, B; Bilski, P; Budzanowski, M; Böttger, R; Eberhardt, K; Hampel, G; Olko, P; Straubing, A

2006-01-01

290

Superconducting inductance-bridge transducer for resonant-mass gravitational-radiation detector  

NASA Astrophysics Data System (ADS)

The sensitivity of cryogenic gravitational-radiation detectors is presently limited by the performance of the transducers. A superconducting ac-pumped inductance bridge is proposed as a new transducer for resonant-mass gravitational-radiation detectors. The impedance matrix of the transducer is computed to determine the input, output, and transfer characteristics of the electromechanical system. It is shown that the dissipative forces exerted on the proof mass by the bridge circuit through the two sidebands cancel each other almost exactly so that the Brownian-motion level is nearly unaffected by the electric sensing circuit. This implies that an effective energy coupling coefficient near unity could be used without being limited by the electrical Nyquist noise. With the parametric up conversion of the signal, the inductance bridge can be coupled to a nearly quantum-limited dc superconducting quantum interference device (SQUID). The sensitivity of the gravitational-radiation detector employing the new superconducting transducer is computed as a function of transducer parameters. It is shown that the proposed transducer, with modest values for its parameters, is capable of matching a high-Q gravitational-radiation antenna, cooled to 50 mK, to a nearly quantum-limited dc SQUID.

Paik, Ho Jung

1986-01-01

291

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

NASA Technical Reports Server (NTRS)

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.

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

1978-01-01

292

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

NASA Astrophysics Data System (ADS)

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.

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

293

A radiation damage test for double-sided silicon strip detectors  

NASA Astrophysics Data System (ADS)

In order to investigate the p-side strip isolation, position sensitivity and charge collection of type-inverted double-sided silicon microstrip detectors, signal amplitude and charge sharing of adjacent strips were measured by using a laser test stand, following the irradiation with a flux of 3.8×10 13 /cm 2 of 12 GeV protons. The irradiated detectors indicated high bulk resistivity, which results in maintaining a position sensitivity of the ohmic contact side even below the full depletion voltage. This fact suggests a possibility of operation of a double-sided detector whose full depletion voltage becomes higher than its breakdown limit because of a radiation damage.

Iwata, Y.; Ohsugi, T.; Ikeda, M.; Kitabayashi, H.; Ohmoto, T.; Kondo, T.; Unno, Y.; Terada, S.; Kohriki, T.; Takashima, R.

2002-08-01

294

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

SciTech Connect

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.

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

1989-09-01

295

Chemical vapor deposited diamond radiation detectors for ultrahigh radiation dose-rate measurements: Response to subnanosecond, 16-MeV electron pulses  

SciTech Connect

Conductivity modulated devices, similar to photoconductors in operation, for use as radiation detectors were fabricated from polycrystalline chemical vapor deposited diamond films. These detectors were designed to operate under extremely high radiation fields with a large dynamic range in both response and speed. Two types of detectors were studied: a parallel-plate device and a surface device (SDT). The radiation used to excite these detectors was minimum ionizing electrons with an energy of 16 MeV and a nominal pulse width of less than 25 ps. The response time of all detectors was less than 45 ps. The sensitivity of the detectors was in the range 10{sup {minus}5}--10{sup {minus}6} A/W. Over the operating range of the detectors, signal saturation was not observed because to the signal size was small in comparison to the applied bias voltage. The detectors appeared to be linear with dose and dose rate over two orders of magnitude, and for dose rates up to 10{sup 13} rad/s. Long-lived signal decay tails contributed to much less than 1% of the signal. The response of a SDT detector appeared to be independent of the orientation of the detector to the incident beam direction when the excitation source is minimum ionizing. It appears that the dose-rate linearity may be extended to a range greater than 10{sup 13} rad/s. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Han, S.; Wagner, R.S.; Joseph, J. [Los Alamos National Laboratory, D429, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, D429, Los Alamos, New Mexico 87545 (United States); Plano, M.A.; Moyer, M.D. [Crystallume, Inc., 3506 Bassett Street, Santa Clara, California 95054 (United States)] [Crystallume, Inc., 3506 Bassett Street, Santa Clara, California 95054 (United States)

1995-12-01

296

Irradiation of thin diamond detectors and radiation hardness tests using MeV protons  

NASA Astrophysics Data System (ADS)

Although numerous studies have confirmed the superb radiation hardness of diamond for high-energy (above 100 MeV) protons, almost no data have been reported in the MeV energy range. Because the interaction mechanism that dominates the displacement damage cross section is different for these two energy regimes, it could be misleading to simply extrapolate the results of previous papers down to low energies. Therefore, the radiation tolerance of a 50 ?m thick single-crystal CVD diamond detector was tested by irradiating it with 4.5 MeV protons. The scanning microbeam allowed for the selective introduction of damage to a small area of the detector. The ion beam-induced current (IBIC) was used to monitor the charge collection efficiency (CCE) degradation due to the electrically active defects produced. The irradiation was stopped when a signal degradation of nearly 3% was observed. For comparison, the procedure was repeated on a 50 ?m thick silicon surface barrier detector (SSBD), for which a significantly higher proton fluence was required to reach the same signal decrease as in the diamond detector. This result can be explained by the different recombination rates of the vacancies and interstitials created in the two materials. The transport properties of electrons and holes in the damaged and virgin areas of the diamond detector were also investigated by 500 keV protons and 6 MeV carbon ions as short-range IBIC probes. The mobility-lifetime products calculated for both charge carriers after fitting the single-carrier Hecht equation indicated that there was more pronounced electron trapping by the radiation-induced defects. The frequently reported effect of polarization in diamond was successfully avoided for 500 keV protons but still remained for 6 MeV carbon ions because an order of magnitude higher ionization rate.

Grilj, V.; Skukan, N.; Jakši?, M.; Kada, W.; Kamiya, T.

2013-07-01

297

Comparison of direct normal irradiance derived from silicon and thermopile global hemispherical radiation detectors  

NASA Astrophysics Data System (ADS)

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.

Myers, Daryl R.

2010-08-01

298

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

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

299

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

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

300

Deconvolving the temporal response of photoelectric x-ray detectors for the diagnosis of pulsed radiations  

NASA Astrophysics Data System (ADS)

Based on the conjugate gradient method, a simple algorithm is presented for deconvolving the temporal response of photoelectric x-ray detectors (XRDs) to reconstruct the resolved time-dependent x-ray fluxes. With this algorithm, we have studied the impact of temporal response of XRD on the radiation diagnosis of hohlraum heated by a short intense laser pulse. It is found that the limiting temporal response of XRD not only postpones the rising edge and peak position of x-ray pulses but also smoothes the possible fluctuations of radiation fluxes. Without a proper consideration of the temporal response of XRD, the measured radiation flux can be largely misinterpreted for radiation pulses of a hohlraum heated by short or shaped laser pulses.

Zou, Shiyang; Song, Peng; Guo, Liang; Pei, Wenbing

2013-09-01

301

Deconvolving the temporal response of photoelectric x-ray detectors for the diagnosis of pulsed radiations  

SciTech Connect

Based on the conjugate gradient method, a simple algorithm is presented for deconvolving the temporal response of photoelectric x-ray detectors (XRDs) to reconstruct the resolved time-dependent x-ray fluxes. With this algorithm, we have studied the impact of temporal response of XRD on the radiation diagnosis of hohlraum heated by a short intense laser pulse. It is found that the limiting temporal response of XRD not only postpones the rising edge and peak position of x-ray pulses but also smoothes the possible fluctuations of radiation fluxes. Without a proper consideration of the temporal response of XRD, the measured radiation flux can be largely misinterpreted for radiation pulses of a hohlraum heated by short or shaped laser pulses.

Zou, Shiyang; Song, Peng; Pei, Wenbing [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China)] [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Guo, Liang [Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900 (China)] [Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900 (China)

2013-09-15

302

Radiation tolerance of epitaxial silicon carbide detectors for electrons, protons and gamma-rays  

NASA Astrophysics Data System (ADS)

Particle detectors were made using semiconductor epitaxial 4H-SiC as the detection medium. The investigated detectors are formed by Schottky contact (Au) on the epitaxial layer and an ohmic contact on the back side of 4H-SiC substrates with different micropipe densities from CREE. For radiation hardness studies, the detectors have been irradiated with protons ( 24 GeV/c ) at a fluence of about 10 14 cm-2 and with electrons (8.2 MeV) and gamma-rays ( 60Co source) at doses ranging from 0 to 40 Mrad. We present experimental data on the charge collection properties by using 5.48, 4.14 and 2.00 MeV ?-particles impinging on the Schottky contact. Hundred percent charge collection efficiency (CCE) is demonstrated for reverse voltages higher than the one needed to have a depletion region equal to the ?-particle projected range, even after the irradiation at the highest dose. By comparing measured CCE values with the outcomes of drift-diffusion simulations, values are inferred for the hole lifetime, ?p, within the neutral region of the charge carrier generation layer. ?p was found to decrease with increasing radiation levels, ranging from 300 ns in non-irradiated detectors to 3 ns in the most irradiated ones. The diffusion contribution of the minority charge carriers to CCE is pointed out.

Nava, F.; Vittone, E.; Vanni, P.; Verzellesi, G.; Fuochi, P. G.; Lanzieri, C.; Glaser, M.

2003-06-01

303

Radiation tolerance of epitaxial silicon carbide detectors for electrons and ?-rays  

NASA Astrophysics Data System (ADS)

Particles detectors were made using semiconductor epitaxial 4H-SiC as the detection medium. The investigated detectors are formed by Schottky contact (Au) on the epitaxial layer and an ohmic contact on the backside of 4H-SiC substrates with different micropipe densities from CREE. For radiation hardness studies, the detectors have been irradiated with electrons (8.2 MeV) and ?-rays ( 60Co source) at fluences and doses ranging from 0 to 9.48×10 14 e/cm 2 and 40 Mrad, respectively. We present experimental data on the charge collection properties by using 4.14 MeV ?-particles impinging on the Schottky contact. Hundred percent Charge Collection Efficiency, CCE, is demonstrated for reverse voltages higher than the one needed to have a depletion region equal to the ?-particle projected range, even after the irradiation at the highest dose. By comparing measured CCE values with the outcomes of drift-diffusion simulations, values are inferred for the hole lifetime, ?p, within the neutral region of the charge carrier generation layer. ?p was found to decrease with increasing radiation levels, ranging from 300 ns in non-irradiated detectors to 3 ns in the most irradiated ones. The diffusion contribution of the minority charge carriers to CCE is pointed out.

Nava, F.; Vittone, E.; Vanni, P.; Fuochi, P. G.; Lanzieri, C.

2003-11-01

304

Capture of carriers by impurity clouds in germanium nuclear-radiation detectors  

SciTech Connect

A correlation between the intensity of low-angle scattering of CO/sub 2/ laser radiation by impurity clouds of radius a = 6--9 ..mu.. and with an average charge loss factor lambda-bar was observed in nuclear-radiation detectors made of high-purity germanium. The nature of this effect was explained by considering the interaction of an impurity cloud with carriers drifting in the electric field of the detector in the case of neutral, partly ionized, and fully ionized clouds. It was found that an impurity cloud is a macroscopic carrier trap; the sign of carriers which are trapped and the capture cross section are determined by the nature of the centers inside the cloud and by the degree of their ionization. If allowance is made for the amplitude spectrum of the detector, the concentration in impurity clouds, and the sign of the charge of the trapped carriers, it is found that the most probable mechanism of the charge losses in a detector is the trapping of holes by neutral donor centers forming clouds (clusters).

Voronkov, V.V.; Voronkova, G.I.; Danengirsh, S.G.; Zubov, B.V.; Kalinushkin, V.P.; Murina, T.M.; Petrova, E.A.; Prokhorov, A.M.; Strokan, N.B.; Chikalova-Luzina, O.P.

1982-10-01

305

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

DOEpatents

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.

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

1993-12-07

306

Charged Particle Measurements on Mars and during Cruise with the Radiation Assessment Detector (MSL/RAD)  

NASA Astrophysics Data System (ADS)

The Radiation Assessment Detector (RAD), part of the Mars Science Laboratory (MSL), has been successfully measuring the energetic particle radiation on the Martian surface since the landing of the Curiosity rover in Gale crater. Furthermore, RAD was already operating for large parts of the ~250-day cruise to Mars, measuring the radiation environment inside the spacecraft. Detailed knowledge of particle-type-dependent energy spectra is important for several reasons. E.g., for one measured differential particle fluxes can be used to validate and evaluate transport models currently used to estimate the radiation exposure on the Martian surface. Another important point of knowing the energy spectra of individual ion species is their differing biological effectiveness in terms of assessing radiation exposure risks for future manned missions to Mars. Here, we will present differential fluxes for different ion species, both for the cruise and the surface phase. As the energy range of these spectra is limited by the maximum energy with that a particle can stop in one of RAD's detectors, we will show integral fluxes for energies above these upper limits where the total energy of the detected particle is not known.

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

2013-12-01

307

Transition Radiation Detector in the D0 colliding beam experiment at Fermilab  

SciTech Connect

The construction, operation and response of the Transition Radiation Detector (TRD) at DO colliding beam experiment at Fermilab are presented. The use of the TRD signal to enhance electron identification and hadronic rejection in the multiparticle background characteristic for the antiproton-proton interactions at the center-of-mass energy of 1.8 TeV is also described and results are discussed.

Piekarz, H.

1995-04-01

308

The geometrical dependence of radiation hardness in planar and 3D silicon detectors  

Microsoft Academic Search

The radiation hardness of planar and 3D silicon detectors fabricated on Float-Zone and epitaxial silicon substrates is compared after exposure to neutron equivalent fluences greater than 1015cm?2. Following irradiation, the Signal Efficiency (SE), expressed as the ratio of the maximum signal after irradiation divided to the maximum signal before irradiation, is shown to depend only on the geometrical distance, L,

C. Davia; S. J. Watts

2009-01-01

309

A detector for imaging of explosions on a synchrotron radiation beam  

Microsoft Academic Search

Synchrotron radiation (SR) offers a unique chance to study the structure of a substance in fast processes. Since SR is emitted\\u000a by electron bunches in a storage ring, the SR burst corresponding to a single bunch may be very short. Should a detector capable\\u000a of detecting SR from a single bunch without mixing signals from different bunches be available, it

V. M. Aulchenko; O. V. Evdokov; I. L. Zhogin; V. V. Zhulanov; E. R. Pruuel; B. P. Tolochko; K. A. Ten; L. I. Shekhtman

2010-01-01

310

Development of phoswich detectors for simultaneous counting of alpha particles and other radiations (emitted from Actinides)  

Microsoft Academic Search

In order to develop actinide monitors, simultaneous counting of ? particles and other radiations has been investigated by means of phoswich detectors. Typical phoswiches devised up to the present consist of the following: ZnS(Ag)\\/NE102A for ? and ?(?) counting, ZnS(Ag)\\/NaI (Tl) or YAP for ? and ?(?) counting, ZnS(Ag)\\/anthracene\\/6Li glass for ?, ?(?), thermal- and fast-neutron counting, etc. Optical filters

Shigekazu Usuda; Kenichiro Yasuda; Satoshi Sakurai

1998-01-01

311

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

NASA Astrophysics Data System (ADS)

Ion Beam Induced Charge (IBIC) is the basic mechanism of the operation of semiconductor detectors and it can lead to Single Event Effects (SEEs) in microelectronic devices. To be able to predict SEEs in ICs and detector responses one needs to be able to simulate the radiation-induced current as the function of time on the electrodes of the devices and detectors. There are analytical models, which work for very simple detector configurations, but fail for anything more complex. Technology Computer Aided Design (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. Here a simulation model based on the Gunn theorem was developed and used with the COMSOL Multiphysics framework, version 3.5. In the model, the induced current can be calculated both directly and in certain cases using the powerful adjoint method. A brief description of the model will be given in the paper with examples for detectors and microelectronic devices using both the direct and the adjoint method.

Vizkelethy, Gyorgy

2011-10-01

312

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

NASA Technical Reports Server (NTRS)

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.

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

1978-01-01

313

Hydrogenated Amorphous Silicon Radiation Detectors: Material Parameters; Radiation Hardness; Charge Collection  

Microsoft Academic Search

Properties of hydrogenated amorphous silicon p -i-n diodes relevant to radiation detection applications were studied. The interest in using this material for radiation detection applications in physics and medicine was motivated by its high radiation hardness and the fact that it can be deposited over large area at relatively low cost. Thick, fully depleted a-Si:H diodes are required for sufficient

Shafi Qureshi

1991-01-01

314

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

SciTech Connect

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

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

2009-04-13

315

Implementation of radiation image detector based on lutetium and gadolinium phosphors  

NASA Astrophysics Data System (ADS)

The clinical use of radiation image detectors is influenced by the degree to which patients are exposed to radiation. Phosphors are being used as the radiation receptor materials in a number of radiation imaging systems for the detection of radiation. Rare earth phosphors such as those of Gd, Y, Lu, and La are attracting attention in particular as they exhibit improved properties. However, there has not been any research on the conditions for the synthesis of these phosphors, including the optimal concentrations in which the sensitizer should be added to them. Therefore, in this study, the optimal conditions for the phosphor synthesis were determined by analyzing the characteristics of the phosphors fabricated using various sensitizer concentrations. The deposition method used to form films of the synthesized phosphors was screen printing. This technique is suitable for large-area deposition and allowed for imaging to be performed in conjunction with a complementary metal-oxide semiconductor (CMOS) image detector. The phosphors synthesized were Gd2O3:Eu and Lu2O3:Eu, and the sensitizer used was citric acid, which was added in varying concentrations (0.00-0.05 g) to the phosphors during synthesis. Films of the phosphors 5 × 5 cm in size, which was the size of the active area of the CMOS image sensor, and 100-250 ?m in thickness were formed. The structural characteristics of the phosphors were determined through X-ray diffraction analyses and scanning electron microscopy, and the optical characteristics through photoluminescence (PL) measurements. A CMOS-based X-ray detector was manufactured by attaching the phosphor films to the CMOS image sensor and evaluating the modulation transfer functions of the images obtained. The results showed that of all the phosphor samples synthesized, the Gd2O3:Eu and Lu2O3:Eu samples synthesized using 0.02 g of citric acid exhibited the best luminescence characteristics.

Lee, Y.; Shin, J.; Oh, K.; Noh, S.; Kim, D.; Kim, J.; Hong, J.; Park, S.; Kim, J.; Nam, S.

2013-03-01

316

Multi-Parameter High-Resolution Spatial Maps of a CdZnTe Radiation Detector Array.  

National Technical Information Service (NTIS)

Resistivity results from a 48x48 pixelated CdZnTe (CZT) radiation detector array are presented alongside X-ray topography and detector mapping with a collimated gamma-ray beam. By using a variety of measurements performed on the same sample and registerin...

1998-01-01

317

Simultaneous measurement of neutron and gamma-ray radiation levels from a TRIGA reactor core using silicon carbide semiconductor detectors  

Microsoft Academic Search

The ability of a SiC detector to measure neutron and gamma radiation levels in a TRIGA reactor's mixed neutron\\/gamma field was demonstrated. Linear responses to an epicadmium neutron fluence rate (up to 3×107 cm-2 s-1) and to a gamma dose rate (0.6-234 krad-Si h-1) were obtained with the detector. Axial profiles of the reactor core's neutron and gamma-ray radiation levels

A. R. Dulloo; F. H. Ruddy; J. G. Seidel; C. Davison; T. Flinchbaugh; T. Daubenspeck

1998-01-01

318

Radiation hardness of silicon detectors based on pre-irradiated silicon  

NASA Astrophysics Data System (ADS)

Radiation hardness of planar detectors processed from pre-irradiated and thermo-annealed n-type FZ silicon substrates, and standard FZ as a reference, was studied. The high purity n-Si wafers with carrier concentration 4.8×10 11 cm -3 were pre-irradiated in Kiev's nuclear research reactor by fast neutrons to fluence of about 10 16 neutrons/cm 2 and thermo-annealed at a temperature of about 850 °C. Silicon diodes were fabricated from standard and pre-irradiated silicon substrates by IRST (Italy). All diodes were subsequently irradiated by fast neutrons at Kiev and Ljubljana nuclear reactors. The dependence of the effective doping concentration as a function of fluence ( Neff=f( ?)) was measured for reference and pre-irradiated diodes. Pre-irradiation of silicon improves the radiation hardness by decreasing the acceptor introduction rate ( ?), thus mitigating the depletion voltage ( Vdep) increase. In particular, ? in reference samples is about 0.017 cm -1, and for pre-irradiated samples is about 0.008 cm -1. Therefore, the method of preliminary irradiation can be useful to increase the radiation hardness of silicon devices to be used as sensors or detectors in harsh radiation environments.

Litovchenko, P. G.; Groza, A. A.; Lastovetsky, V. F.; Barabash, L. I.; Starchik, M. I.; Dubovoy, V. K.; Bisello, D.; Giubilato, P.; Candelori, A.; Rando, R.; Litovchenko, A. P.; Khomenkov, V.; Wahl, W.; Boscardin, M.; Zorzi, N.; Dalla Betta, G.-F.; Cindro, V.; Mikelsen, M.; Monakhov, E. V.; Svensson, B. G.

2006-11-01

319

Radiation Hard Hybrid Pixel Detectors, and a bb¯ Cross-Section Measurement at the CMS Experiment  

NASA Astrophysics Data System (ADS)

Measurements of heavy flavor quark production at hadron colliders provide a good test of the perturbative quantum chromodynamics (pQCD) theory. It is also essential to have a good understanding of the heavy quark production in the search for new physics. Heavy quarks contribute to backgrounds and signals in measurements of higher mass objects, such as the Higgs boson. A key component to each of these measurements is good vertex resolution. In order to ensure reliable operation of the pixel detector, as well as confidence in the results of analyses utilizing it, it is important to study the effects of the radiation on the detector. In the first part of this dissertation, the design of the CMS silicon pixel detector is described. Emphasis is placed on the effects of the high radiation environment on the detector operation. Measurements of the charge collection efficiency, interpixel capacitance, and other properties of the pixel sensors as a function of the radiation damage are presented. In the second part, a measurement of the inclusive bb¯ production cross section using the b ? muD 0X, D0 ? Kpi decay chain with data from the CMS experiment at the LHC is presented. The data were recorded with the CMS experiment at the Large Hadron Collider (CERN) in 2010 using unprescaled single muon triggers corresponding to a total luminosity of 25 pb-1. The differential cross section is measured for pD0mT > 6 GeV/c and |eta| < 2.4 corresponding to a total cross section of 4.36+/-0.54(stat.) +0.28-0.25 (sys.)+/-0.17( B )+/-0.23( L ) mu b.

Sibille, Jennifer A.

320

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

NASA Astrophysics Data System (ADS)

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

Li, Zheng

2011-12-01

321

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

SciTech Connect

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

Li Z.

2011-05-11

322

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

NASA Astrophysics Data System (ADS)

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.

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

2012-07-01

323

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

SciTech Connect

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.

Cho, Gyuseong.

1992-03-01

324

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

325

ATLAS Transition Radiation Tracker (TRT): Straw tube gaseous detectors at high rates  

NASA Astrophysics Data System (ADS)

The ATLAS Transition Radiation Tracker (TRT) is the outermost of the three tracking subsystems of the ATLAS Inner Detector. The ATLAS detector is located at LHC/CERN. We report on how these gaseous detectors ("straw tubes") are performing during the ATLAS 2011 and 2012 runs where the TRT experiences higher rates than previously encountered. The TRT contains around 300 000 thin-walled proportional-mode drift tubes providing on average 30 two-dimensional space points with an intrinsic resolution of approximately 120?m for charged particle tracks with |?|<2 and pT>0.5GeV. Along with continuous tracking, the TRT provides electron identification capability through the detection of transition radiation X-ray photons. During the ATLAS 2012 proton-proton data runs, the TRT is operating successfully while being subjected to the highest rates of incident particles ever experienced by a large scale gaseous tracking system. In the second half of 2012, the TRT has collected data in an environment with instantaneous proton-proton luminosity around 0.8×1034cm-2s-1. While shadowing effects caused by up to 40 simultaneous proton-proton collisions per bunch crossing are noticeable, the TRT performs significantly better than design. It also contributes to the combined tracking system pT resolution and to electron identification. During LHC heavy ion running in 2011, the TRT contributed to measuring track pT even in events where overall occupancy exceeded 50%.

Vogel, Adrian

2013-12-01

326

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

SciTech Connect

Epitaxial grown thick layers (>100 {mu}m) 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{center_dot}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{center_dot}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, in epitaxial layers. The {open_quotes}sinking{close_quotes} 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{center_dot}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{center_dot}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.

Li, Z. [Brookhaven National Lab., Upton, NY (United States); Eremin, V.; Ilyashenko, I.; Ivanov, A. [Russian Academy of Sciences, St-Petersburg (Russian Federation). Ioffe Physico-Technical Institute] [and others

1997-11-01

327

A high rejection transition radiation detector prototype to distinguish positrons from protons in a cosmic ray space laboratory  

NASA Astrophysics Data System (ADS)

We have carefully implemented a transition radiation detector prototype in order to design a similar device having 75 × 150 cm2 active surface that will discriminate positrons from protons. This detector will be part of the spectrometer of the experiment WIZARD, planned to fly at 180 miles altitude on the NASA Space Station "FREEDOM" to search for primordial antimatter. Since the positron to proton ratio is expected to be of the order of 10-4, we have pushed the proton rejection factor of the spectrometer beyond this value using a compact transition radiation detector equipped with properly designed "cluster counting" electronics.

Barbarito, E.; Bellotti, R.; Cafagna, F.; Calicchio, M.; Castellano, M.; De Cataldo, G.; De Marzo, C.; Erriquez, O.; Favuzzi, C.; Fusco, P.; Giglietto, N.; Liuzzi, R.; Marangelli, B.; Mongelli, M.; Perchiazzi, M.; Rainò, A.; Sacchetti, A.; Spinelli, P.

1992-03-01

328

Concept of Double Peak electric field distribution in the development of radiation hard silicon detectors  

NASA Astrophysics Data System (ADS)

The concept of Double Peak (DP) electric field distribution is considered for the analysis of operational characteristics of irradiated silicon detectors. The key point of the model is trapping of equilibrium carriers to the midgap energy levels of radiation-induced defects, which leads to a non-uniform distribution of space charge concentration with positively and negatively charged regions adjacent to the p + and n + contacts, respectively. In our new development of the DP model we consider a non-depleted base region in between the space charge regions as a high resistivity bulk, which operates as a drift region with a non-negligible electric field. Electric field characteristics of detectors processed from n-type MCZ Si wafers using various technological procedures, and irradiated by 1 MeV neutrons and 24 GeV/ c protons, have been compared. Electric field profiles have been reconstructed from DP pulse response of heavily irradiated detectors and calculated by the simulation of DP electric field distribution caused by carrier trapping. It is shown that detectors from n-type MCZ Si irradiated by 24 GeV/ c protons do not show typical space charge sign inversion up to the irradiation fluence of about 2.2×10 15 p/cm 2 and the region with a positive charge dominates over a negatively charged region.

Verbitskaya, E.; Eremin, V.; Li, Z.; Härkönen, J.; Bruzzi, M.

2007-12-01

329

On the spectrometric performance limit of radiation detectors based on semi-insulating GaAs  

NASA Astrophysics Data System (ADS)

In this work, basic tasks related to the spectrometric performance of X- and ?-ray radiation-imaging detectors based on semi-insulating (SI) GaAs are studied. The state of the art in this field is reported. The importance of a low-noise front-end read-out electronic chain is demonstrated. Four different charge-sensitive preamplifiers are tested and compared. The investigation of SI GaAs detectors considered for imaging applications is focused on the study of different electrode technologies. A blocking electrode is obtained by a surface Schottky barrier or an MBE-grown P+ layer. An ohmic N+ contact is fabricated using alloyed AuGeNi metallization or an advanced, quasi-ohmic non-injecting system created by a non-stoichiometric buffer grown by low-temperature MBE at the metal-semiconductor interface. This latter approach is considered as an improvement of the “non-alloyed” ohmic contact. The pulse height spectra obtained with 241Am and 57Co sources and corresponding detector energy resolution are evaluated. The role of detector geometry and temperature on the spectrometric performance is studied.

Za?ko, B.; Dubecký, F.; Bohá?ek, P.; Gombia, E.; Frigeri, P.; Mosca, R.; Franchi, S.; Huran, J.; Ne?as, V.; Seká?ová, M.; Förster, A.; Kordoš, P.

2004-09-01

330

Performance of CdZnTe geometrically weighted semiconductor Frisch grid radiation detectors  

SciTech Connect

Semiconductor Frisch grid radiation detectors have been manufactured and tested with encouraging results. Resolution enhancement occurs as a result of combining the geometric weighting effect, the small pixel effect and the Frisch grid effect. The devices are operated at ambient temperature without any pulse shape correction, rejection and compensation techniques. The new devices are manufactured from CdZnTe and do not require any cooling for operation. The geometrically weighted detectors have only one signal output to a standard commercially available Ortec 142A preamplifier. The detectors operate with simple commercially available NIM electronics, hence the device design can be coupled to any typical NIM system without the need for special electronic instruments or circuits. Geometrically weighted detectors that are 1 cubic centimeter in volume were fabricated from counter grade material, yet have shown room temperature energy resolution of 7.5% FWHM (at 29 C) for {sup 57}Co 122 keV gamma rays and 2.68% FWHM (at 23 C) for {sup 137}Cs 662 keV gamma rays.

McGregor, D.S. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering and Radiological Sciences] [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering and Radiological Sciences; Rojeski, R.A. [Etec Systems, Inc., Hayward, CA (United States)] [Etec Systems, Inc., Hayward, CA (United States)

1999-06-01

331

Soft X-Ray Spectrometer Using 100-Pixel STJ Detectors for Synchrotron Radiation  

SciTech Connect

Fluorescent X-ray absorption fine structure (XAFS) is an important tool for material analysis, especially for the measurement of chemical states or local structures of elements. Semiconductor detectors are usually used for separating the fluorescent of elements in question from background fluorescence. However, the semiconductor detectors cannot always discriminate K-lines of light elements and L-lines of various elements as different X-ray peaks at an energy range below about 3 keV. Superconducting tunnel junction (STJ) detectors are promising device for the soft X-ray at synchrotron radiation beam lines because of excellent energy resolution, high detection efficiency, and high counting rate. We are constructing a fluorescent X-ray spectrometer having 100-pixel array of STJs with 200 {mu}m square. The array detector is mounted on a liquid cryogen-free {sup 3}He cryostat. The sensitive area is the largest among the superconducting X-ray spectrometers operating at synchrotron beam lines. Each pixel is connected to a room temperature readout circuit that consists of a charge sensitive amplifier and a pulse height analyzer. The spectrometer will achieve a total solid angle of {approx}0.01 sr and a maximum counting rate of more than 1 M count per second. The present status of developments of our fluorescent X-ray spectrometer was reported.

Shiki, Shigetomo; Zen, Nobuyuki; Ukibe, Masahiro; Ohkubo, Masataka [National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)

2009-12-16

332

Design, fabrication and performance optimization of bi-polar blocking planar HPGe radiation detector  

NASA Astrophysics Data System (ADS)

A prototype planar radiation detector is designed, fabricated and characterized using bi-polar contact deposited on high purity single crystal germanium (HPGe). Performances of planar and semi-planar detectors are carried out for their low background counting and high absolute efficiency for high-energy photons applications. For this study, 40mm ? 15mm (diameter to vertical height) p-type HPGe samples with dislocation density EPD 3000 cm-2 are taken from HPGe ingots grown by Czochralski method. After a successful mechanical preparation, and standard cleaning and polishing procedure, samples are chemically etched by using a mixture of highly concentrated acids HF:HNO3 (1:4) in order to remove the surface oxides. A bi-polar blocking layer of amorphous germanium (a-Ge) is deposited on both the samples using low temperature RF sputtering plasma in a pre-mix precursor of H2 (15%) and Ar. For this, an optimized dose of the plasma power and chamber pressure is used for a controlled low temperature. The process was completed with the evaporation of Ohmic contacts using electron beam evaporator. This is worth noticing that special care is introduced during the handling of these samples, especially for the bi-polar blocking and metal contact layers deposition. Finally, the fabricated detectors are characterized at 77K temperature. In this paper, we show the results from the first prototype detector made of home grown crystals at USD.

Khizar, Muhammad; Wang, Guojian; Mei, Dongming

2013-03-01

333

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

NASA Astrophysics Data System (ADS)

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.

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

2012-05-01

334

Very Low-Power Consumption Analog Pulse Processing ASIC for Semiconductor Radiation Detectors  

SciTech Connect

We describe a very-low power consumption circuit for processing the pulses from a semiconductor radiation detector. The circuit was designed for use with a cadmium zinc telluride (CZT) detector for unattended monitoring of stored nuclear materials. The device is intended to be battery powered and operate at low duty-cycles over a long period of time. This system will provide adequate performance for medium resolution gamma-ray pulse-height spectroscopy applications. The circuit incorporates the functions of a charge sensitive preamplifier, shaping amplifier, and peak sample and hold circuit. An application specific integrated circuit (ASIC) version of the design has been designed, built and tested. With the exception of the input field effect transistor (FET), the circuit is constructed using bipolar components. In this paper the design philosophy and measured performance characteristics of the circuit are described.

Wessendorf, K.O.; Lund, J.C.; Brunett, B.A.; Laguna, G.R.; Clements, J.W.

1999-08-23

335

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

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

336

Effect of surface preparation technique on the radiation detector performance of CdZnTe  

NASA Astrophysics Data System (ADS)

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.

Duff, M. C.; Hunter, D. B.; Burger, A.; Groza, M.; Buliga, V.; Black, D. R.

2008-02-01

337

Performance enhancements of compound semiconductor radiation detectors using digital pulse processing techniques  

NASA Astrophysics Data System (ADS)

The potential benefits of using compound semiconductors for X-ray and gamma ray spectroscopy are already well known. Radiation detectors based on high atomic number and wide band gap compound semiconductors show high detection efficiency and good spectroscopic performance even at room temperature. Despite these appealing properties, incomplete charge collection is a critical issue. Generally, incomplete charge collection, mainly due to the poor transport properties of the holes, produces energy resolution worsening and the well known hole tailing in the measured spectra. In this work, we present a digital pulse processing (DPP) system for high resolution spectroscopy with compound semiconductor radiation detectors. The DPP method, implemented on a PC platform, performs a height and shape analysis of the detector pulses (preamplifier output pulses), digitized by a 14-bit, 100 MHz ADC. Fast and slow shaping, automatic pole-zero adjustment, baseline restoration and pile-up rejection allow precise pulse height measurements both at low and high counting rate environments. Pulse shape analysis techniques (pulse shape discrimination, linear and nonlinear pulse shape corrections) to compensate for incomplete charge collection were also implemented. The results of spectroscopic measurements on a planar CdTe detector show the high potentialities of the system, obtaining low tailing in the measured spectra and energy resolution quite close to the theoretical limit. High-rate measurements (up to 820 kcps) exhibit the excellent performance of the pulse height analysis and the benefits of pulse shape techniques for peak pile-up reduction in the measured spectra. This work was carried out in the framework of the development of portable X-ray spectrometers for both laboratory research and medical applications.

Abbene, L.; Gerardi, G.

2011-10-01

338

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

NASA Astrophysics Data System (ADS)

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

Baptista, Brian

339

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

SciTech Connect

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.

Jing, T. [Univ. of California, Berkeley, CA (United States). Dept. of Engineering-Nuclear Engineering]|[Lawrence Berkeley Lab., CA (United States). Physics Div.

1995-05-01

340

An assessment of radiation damage in space-based germanium detectors due to solar proton events  

NASA Astrophysics Data System (ADS)

Radiation effects caused by solar proton events will be a common problem for many types of sensors on missions to the inner solar system because of the long cruise phases coupled with the inverse square scaling of solar particle events. As part of a study in support of the BepiColombo mission to Mercury we have undertaken a comprehensive series of tests to assess these effects on a wide range of sensors. In this paper, we report on the measurements on a large volume coaxial Ge detector which was exposed to simulated solar proton spectra of integrated fluences 8×10, 6×10 and 6×10protonscm. After each irradiation the detectors performance was accessed in terms of energy resolution, efficiency and activation. The detector was then annealed and the measurements repeated before the next irradiation. The minimum operational performance criteria were based on the resolution and efficiency requirements necessary to detect and separate specific radioisotope emission lines from a planetary regolith. Specifically that the energy resolution be restored to 5 keV FWHM at 1332 keV and the detection efficiency be degraded to no more than 10% of its pre-irradiation value. The key conclusion of this study is that even after a modest solar proton event the detector requires extensive annealing. After exposure to an event of integral fluence ˜8×10protonscm this amounts to ˜1 week duration at 100C, whereas for a fluence of ˜6×10protonscm, the detector requires 3.5 months of annealing to satisfy the minimum operational performance requirements and 4.5 months to return the energy resolution to <3keV FWHM at 1332 keV. As a consequence such an instrument will require constant, planned and active management throughout its operational lifetime. The impact on spacecraft operations including resource management therefore needs careful consideration.

Owens, Alan; Brandenburg, S.; Buis, E.-J.; Kiewiet, H.; Kraft, S.; Ostendorf, R. W.; Peacock, A.; Quarati, F.; Quirin, P.

2007-12-01

341

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

NASA Astrophysics Data System (ADS)

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.

Taylor, Edward W.

2006-09-01

342

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

SciTech Connect

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.

Danny Dotson; John Mammosser

2005-05-01

343

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

SciTech Connect

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.

Figueroa, Rodolfo; Belmar, Felipe [Laboratorio XRF, Departmento de Ciencias Fisicas Universidad de La Frontera, Temuco (Chile)

2009-01-29

344

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

SciTech Connect

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

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

1986-03-11

345

Synchrotron radiation coronary angiography with a dual-beam, dual-detector imaging system  

NASA Astrophysics Data System (ADS)

This is a study of the use of a dual-beam, dual-detector synchrotron radiation system for transvenous coronary angiography in a human subject. This system eliminates the need for rapid beam switching, increases X-ray fluence by a factor of about 2.5, and makes it possible to record high- and low-energy images simultaneously, thus excluding artifacts arising from time subtraction. Besides coronary angiography, it may be possible to image the vertebral-basilar arterial circulation with this system.

Rubenstein, E.; Giacomini, J. C.; Gordon, H. J.; Thompson, A. C.; Brown, G.; Hofstadter, R.; Thomlinson, W.; Zeman, H. D.

1990-05-01

346

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

SciTech Connect

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.

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

2007-07-01

347

Ausheilung von Strahlungsschaeden in extrinsischen Halbleiterdetektoren mit Bleichalkogeniddiodenlasern. Abschlussbericht. (Annealing of radiation damages in extrinsic semiconductor detectors with lead chalkogenide diode lasers. Final report).  

National Technical Information Service (NTIS)

Highly sensitive, extrinsic semiconductor detectors are used at cryogenic temperatures in infrared satellite telescopes for astronomical applications. Calibration and sensitivity of the detectors are changed by high-energy radiation in the earth orbit. Co...

U. P. Schiessl M. Tacke

1991-01-01

348

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

ScienceCinema

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.

349

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

SciTech Connect

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.

Bolotnikov,A.

2009-06-02

350

Radiation Hardness Tests of a Scintillation Detector with Wavelength Shifting Fiber Readout  

SciTech Connect

We have performed radiation tolerance tests on the BCF-99-29MC wavelength shifting fibers and the BC404 plastic scintillator from Bicron as well as on silicon rubber optical couplers. We used the 60Co gamma source at the Instituto de Ciencias Nucleares facility to irradiate 30-cm fiber samples with doses from 50 Krad to 1 Mrad. We also irradiated a 10x10 cm2 scintillator detector with the WLS fibers embedded on it with a 200 krad dose and the optical conectors between the scintillator and the PMT with doses from 100 to 300 krad. We measured the radiation damage on the materials by comparing the pre- and post-irradiation optical transparency as a function of time.

Alfaro, R.; Sandoval, A. [Instituto de Fisica - UNAM (Mexico); Cruz, E.; Martinez, M. I.; Paic, G. [Instituto de Ciencias Nucleares - UNAM (Mexico); Montano, L. M. [CINVESTAV (Mexico)

2006-09-25

351

MOS-transistor radiation detectors and X-ray dose-enhancement effects  

NASA Astrophysics Data System (ADS)

Sandia National Laboratory CMOS IC dose detectors and 3N161 MOS Transistors were evaluated as pulsed X-radiation dosimeters and used as monitors to measure dose-enhancement effects. Measurements were made in the photon environments from the HydraMITE II, SPR III, MBS and PITHON radiation sources. The dosimeter evaluation data suggest that the 3N161 MOS transistors are useful dosimeters for measuring flash X-ray-induced doses in the oxide layers of modern MOS integrated circuits. However, dose-enhancement calculations indicate that Monte Carlo codes, using 1-D geometries and calculated source spectra, consistently overpredict measured dose-enhancement ratios by factors as large as two.

Posey, L. D.; Wrobel, T. F.; Evans, D. C.; Beezhold, W.; Kelly, J. G.

1985-12-01

352

MOS-transistor radiation detectors and X-ray dose-enhancement effects  

NASA Astrophysics Data System (ADS)

Sandia National Laboratory (SNL) CMOS IC dose detectors and 3N161 MOS Transistors were evaluated as pulsed X-radiation dosimeters and used as monitors to measure dose-enhancement effects. Measurements were made in the photon environments from the HydraMITE II, SPR III, MBS and PITHON radiation sources. The dosimetric evaluation data suggest that the 3N161 MOS transistors are useful dosimeters for measuring flash X-ray-induced doses in the oxide layers of modern metal-oxide-semiconductor (MOS) integrated circuits. However, dose-enhancement calculations indicate that Monte Carlo codes, using 1-D geometries and calculated source spectra, consistently overpredict measured dose-enhancement ratios by factors as large as two.

Posey, L. D.; Wrobel, T. F.; Evans, D. C.; Beezhold, W.; Kelly, J. G.; MacCallum, C. J.; Coppage, F. N.; Luera, T. F.; Smith, A. J.

1985-08-01

353

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

SciTech Connect

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).

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

1993-01-01

354

Photoemission analysis of chemically modified TlBr surfaces for improved radiation detectors  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

355

Transient current analysis of a GaN radiation detector by TCAD  

NASA Astrophysics Data System (ADS)

A gallium nitride (GaN) Schottky diode radiation detector has been fabricated with a successfully demonstrated radiation response to alpha particles and neutrons when using Li as a convertor. In order to understand the charge collection process for further device modification, the Sentaurus TCAD software package is employed to quantitatively study the transient current produced by energetic charge particles. By comparing the simulation and experimental results, especially the capacitance-voltage relationship and charge collection efficiency, the device parameters and physics models used for the simulation are validated. The time behavior of the transient current is studied, and the carrier generation/loss by impact ionization, recombination, and trapping are discussed. The total collected charge contributed by various components, such as drift, funneling, and diffusion are also analyzed.

Wang, Jinghui; Mulligan, Padhraic L.; Cao, Lei R.

2014-10-01

356

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

DOEpatents

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

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

2013-02-12

357

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

358

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

SciTech Connect

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

Narayan, Raman D.; Miranda, Ryan; Rez, Peter [Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States)

2012-03-15

359

Study of electric field distribution and low frequency noise of CdZnTe radiation detectors  

NASA Astrophysics Data System (ADS)

Polarization phenomena in a metal-semiconductor-metal (M-S-M) structure of metallic Schottky contacts deposited on CdZnTe radiation detectors were studied. We evaluate the distribution of the electric field along the biased M-S-M structure by Pockels measurements. The results show that almost all the electric field is developed across the depletion layer of the reverse-biased contact. The noise measurements of the CdZnTe detectors studied show that the dominant noise is 1/fm noise. The 1/fm noise, with the parameter m close to one, is present at frequencies below 100 Hz and its bandwidth decreases in the course of the polarization process. At higher frequencies, we observed an increase of the m parameter to 2, which indicates a strengthened effect of the generation-recombination processes. In the frequency band of dominating 1/fm = 1 noise, the increase of magnitude of the noise spectral density was proportional to the power of 6, in relation to the current through the detector. This high value is explained as a result of a screening effect of the space charge buildup during the polarization.

Sik, O.; Grmela, L.; Elhadidy, H.; Dedic, V.; Sikula, J.; Grmela, P.; Franc, J.; Skarvada, P.; Holcman, V.

2013-06-01

360

The Medipix2-based network for measurement of spectral characteristics and composition of radiation in ATLAS detector  

NASA Astrophysics Data System (ADS)

The ATLAS detector is now installed at the CERN LHC and a precise evaluation of the radiation environment within and around the detector is required to understand the performance of the various detector systems, and to predict their useful lifetime. Furthermore, validation of earlier Monte Carlo predictions about the radiation field in ATLAS is necessary. In particular, it is important to perform these measurements in the early phases of the LHC operation. Many other radiation measuring devices lack sensitivity to low doses, and usually do not provide information on the composition of the radiation during this low intensity period. A network of 15 ATLAS-MPX devices has been installed at various positions in the ATLAS detector. These devices are capable of providing quantitative real-time information on the fluxes and flux distributions of the main radiation types in the experiment, including slow and fast neutrons. The technical description of the ATLAS-MPX detector network as well as the principles of the data analysis is presented.

Vykydal, Z.; Bouchami, J.; Campbell, M.; Dolezal, Z.; Fiederle, M.; Greiffenberg, D.; Gutierrez, A.; Heijne, E.; Holy, T.; Idarraga, J.; Jakubek, J.; Kral, V.; Kralik, M.; Lebel, C.; Leroy, C.; Llopart, X.; Maneuski, D.; Nessi, M.; O'Shea, V.; Platkevic, M.; Pospisil, S.; Suk, M.; Tlustos, L.; Vichoudis, P.; Visschers, J.; Wilhelm, I.; Zemlicka, J.

2009-08-01

361

Thermodynamics of post-growth annealing of cadmium zinc telluride nuclear radiation detectors  

NASA Astrophysics Data System (ADS)

Nuclear Radiation Detectors are used for detecting, tracking, and identifying radioactive materials which emit high-energy gamma and X-rays. The use of Cadmium Zinc Telluride (CdZnTe) detectors is particularly attractive because of the detector's ability to operate at room temperature and measure the energy spectra of gamma-ray sources with a high resolution, typically less than 1% at 662 keV. While CdZnTe detectors are acceptable imperfections in the crystals limit their full market potential. One of the major imperfections are Tellurium inclusions generated during the crystal growth process by the retrograde solubility of Tellurium and Tellurium-rich melt trapped at the growth interface. Tellurium inclusions trap charge carriers generated by gamma and X-ray photons and thus reduce the portion of generated charge carriers that reach the electrodes for collection and conversion into a readable signal which is representative of the ionizing radiation's energy and intensity. One approach in resolving this problem is post-growth annealing which has the potential of removing the Tellurium inclusions and associated impurities. The goal of this project is to use experimental techniques to study the thermodynamics of Tellurium inclusion migration in post-growth annealing of CdZnTe nuclear detectors with the temperature gradient zone migration (TGZM) technique. Systematic experiments will be carried out to provide adequate thermodynamic data that will inform the engineering community of the optimum annealing parameters. Additionally, multivariable correlations that involve the Tellurium diffusion coefficient, annealing parameters, and CdZnTe properties will be analyzed. The experimental approach will involve systematic annealing experiments (in Cd vapor overpressure) on different sizes of CdZnTe crystals at varying temperature gradients ranging from 0 to 60°C/mm (used to migrate the Tellurium inclusion to one side of the crystal), and at annealing temperatures ranging from 500 to 800°C. The characterization techniques that will be used to quantify the effects of the post-growth annealing experiments include: 1) 3D infrared transmission microscopy to measure the size, distribution, and concentration of Tellurium inclusions; 2) current-voltage measurements to determine the effect of post-growth annealing on the resistivity of CdZnTe crystals; and 3) X-ray diffraction topography, available at the National Synchrotron Light Source (NSLS) facilities at Brookhaven National Laboratory (BNL), to measure the correlation between device performance and annealing conditions

Adams, Aaron Lee

362

PASSIVATION OF SEMICONDUCTOR SURFACES FOR IMPROVED RADIATION DETECTORS: X-RAY PHOTOEMISSION ANALYSIS  

SciTech Connect

Surface passivation of device-grade radiation detector materials was investigated using x-ray photoelectron spectroscopy in combination with transport property measurements before and after various chemical treatments. Specifically Br-MeOH (2% Br), KOH with NH{sub 4}F/H{sub 2}O{sub 2} and NH{sub 4}OH solutions were used to etch, reduce and oxidize the surface of Cd{sub (1-x)}Zn{sub x}Te semiconductor crystals. Scanning electron microscopy was used to evaluate the resultant microscopic surface morphology. Angle-resolved high-resolution photoemission measurements on the valence band electronic structure and core lines were used to evaluate the surface chemistry of the chemically treated surfaces. Metal overlayers were then deposited on these chemically treated surfaces and the I-V characteristics measured. The measurements were correlated to understand the effect of interface chemistry on the electronic structure at these interfaces with the goal of optimizing the Schottky barrier height for improved radiation detector devices.

Nelson, A; Conway, A; Reinhardt, C; Ferreira, J; Nikolic, R; Payne, S

2007-12-10

363

Scintillation detectors based on poly-2,4-dimethylstyrene: Structure peculiarities and radiation damage  

SciTech Connect

Scintillation detectors based on poly-2,4-dimethyl styrene (P-2,4-DMS) are studied. Investigated is the influence of two methyl groups present in the benzene ring on the energy, spectral and structural characteristics of the polymer. The said factors are assumed to result in the detectors high light output and radiation resistance. It is shown that under radiolysis (77 K) the radiation yield of the paramagnetic centers of P-2,4-DMS exceeds that of polystyrene (PST) by {approximately} 1.5. Unlike PST film, the luminescence spectra of P-2,4-DMS are characterized by the presence of both excimer (320-340 nm) and monomer (292 nm) bands. Revealed are the distinction in the nature of the optical characteristics of macroradicals and the efficiency of energy transfer in gamma-irradiated PST and P-2,4-DMS scintillators. The relation between the super-molecular structure of the polymers and the interaction of their macroradicals with molecular O{sub 2} is stated.

Gunder, O.A.; Voronkina, N.I.; Kopina, I.V. [Institute for Single Crystals, Kharkov (Ukraine)] [Institute for Single Crystals, Kharkov (Ukraine)

1995-08-01

364

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

NASA Astrophysics Data System (ADS)

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

Luiz Silva, Cesar

2004-10-01

365

A Micro-Cantilever Based Photoacoustic Detector of Terahertz Radiation for Chemical Sensing  

NASA Astrophysics Data System (ADS)

In this paper we describe a novel photoacoustic detector that can detect radiation in the Terahertz/sub-millimeter (THz/smm) spectral range, is immune to the effect of standing waves, and potentially can have spectral response that is independent of the absorption path length, thus offering crucial advantages for acquisition of THz/smm molecular spectra. The photoacoustic effect occurs when the energy from electromagnetic waves is absorbed by molecules and collisionally transferred into translational energy, thus resulting in local heating induced by the radiation. If radiation produced by the source is modulated, an acoustic wave results which can be detected by a pressure sensitive device such as a microphone or a cantilever. This transduction of the THz signal into a photoacoustic wave is what makes this approach insensitive to the detrimental standing waves associated with traditional THz sensors and allows for a significant reduction in the size of the absorption cell. A Microelectromechanical system (MEMS) cantilever pressure sensor was designed, modeled, fabricated, and tested for sensing the photoacoustic response of gases to THz/smm radiation. Here we present our manufacturing, experimental set-up and most recent spectroscopic results, which demonstrate the capabilities of this spectroscopic technique.

Glauvitz, Nathan E.; Coutu, Ronald A. Coutu, Jr.; Kistler, Michael N.; Hamilton, Ryan F.; Petkie, Douglas T.; Medvedev, Ivan R.

2013-06-01

366

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

NASA Astrophysics Data System (ADS)

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

Hong, Wan-Shick

1995-04-01

367

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

SciTech Connect

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

Hong, Wan-Shick

1995-04-01

368

Superconducting nanostructured detectors capable of single photon counting of mid-infrared optical radiation  

NASA Astrophysics Data System (ADS)

We report on our progress in research and development of ultrafast superconducting single-photon detectors (SSPDs) based on ultrathin NbN nanostructures. Our SSPDs were made of the 4-nm-thick NbN films with Tc ~11 K, patterned as meander-shaped, 100-nm-wide strips, and covering an area of 10×10 ?m2. The detectors exploit a combined detection mechanism, where upon a single-photon absorption, a hotspot of excited electrons and redistribution of the biasing supercurrent, jointly produce a picosecond voltage transient signal across the superconducting nanostripe. The SSPDs are typically operated at 4.2 K, but their sensitivity in the infrared radiation range can be significantly improved by lowering the operating temperature from 4.2 K to 2 K. When operated at 2 K, the SSPD quantum efficiency (QE) for visible light photons reaches 30-40%, which is the saturation value limited by the optical absorption of our 4-nm-thick NbN film. With the wavelength increase of the incident photons,the QE of SSPDs decreases significantly, but even at the wavelength of 6 ?m, the detector is able to count single photons and exhibits QE of about 10-2 %. The dark (false) count rate at 2 K is as low as 2x10-4 s,-1 which makes our detector essentially a background-limited sensor. The very low dark-count rate results in a noise equivalent power (NEP) below 10-18 WHz-1/2 for the mid-infrared range (6 ?m). Further improvement of the SSPD performance in the mid-infrared range can be obtained by substituting NbN for another, lower-Tc materials with a narrow superconducting gap and low quasiparticles diffusivity. The use of such superconductors should shift the cutoff wavelength below 10 ?m.

Milostnaya, I.; Korneev, A.; Minaeva, O.; Rubtsova, I.; Slepneva, S.; Seleznev, V.; Chulkova, G.; Okunev, O.; Smirnov, K.; Voronov, B.; Gol'tsman, G.; Slysz, W.; Kitaygorsky, J.; Cross, A.; Pearlman, A.; Sobolewski, Roman

2005-09-01

369

Development of Radiation Detectors Based on Hydrogenated Amorphous Silicon and its Alloys.  

NASA Astrophysics Data System (ADS)

Hydrogenated amorphous silicon and related materials have been applied to radiation detectors, utilizing their good radiation resistance and the feasibility of making deposits over a large area at low cost. Effects of deposition parameters on various material properties of a-Si:H have been studied to produce a material satisfying the requirements for specific detection application. Thick(~50 mu m), device quality a-Si:H p-i-n diodes for direct detection of minimum ionizing particles have been prepared with low internal stress by a combination of low temperature growth, He-dilution of silane, and post annealing. The structure of the new film contained voids and tiny crystalline inclusions and was different from the one observed in conventional a-Si:H. Deposition on patterned substrates was attempted as an alternative to controlling deposition parameters to minimize substrate bending and delamination of thick a-Si:H films. Growth on an inversed-pyramid pattern reduced the substrate bending by a factor of 3 ~ 4 for the same thickness film. Thin (0.1-0.2 ?m) films of a-Si:H and a-Si:C:H have been applied to microstrip gas chambers to control gain instabilities due to charges on the substrate. Light sensitivity of the a-Si:H sheet resistance was minimized and the surface resistivity was successfully controlled in the range of 10^ {12}~ 10^{17} Omega/ square by carbon alloying and boron doping. Performance of the detectors with boron-doped a-Si:C:H layers was comparable to that of electronic-conducting glass. Hydrogen dilution of silane has been explored to improve electrical transport properties of a-Si:H material for high speed photo-detectors and TFT applications. Various electrical properties of the hydrogen-diluted a-Si:H showed factors of 3 ~ 10 improvements at the expense of increased residual stress. The optimal material characteristics for TFT application appeared at deposition conditions corresponding to the onset of crystalline formation, indicating that the enhancement of the electrical properties is due to the superior amorphous matrix not to the presence of crystalline phase. Material properties of the a-Si:H based materials can be easily adapted to the characteristics required for individual applications by modifying fabrication conditions and procedures. This asset, in addition to the advantages of large area capability and radiation hardness, makes a-Si:H an attractive candidate for radiation detection applications.

Hong, Wan-Schick

1995-01-01

370

Analysis of divacancy related traps induced by proton, neutron and gamma radiation in high resistivity silicon detectors1  

Microsoft Academic Search

Defects with deep levels induced in high-resistivity silicon detectors by low and high radiation fluence of protons and neutrons are studied using capacitance and current DLTS. Numerical simulation of I-DLTS and C-DLTS spectra based on the model of charge carrier emission and redistribution of electric field in the detector enabled one to perform the detailed investigation of DLTS spectra. It

V. Eremin; A. Ivanov; E. Verbitskaya; Z. Li; S. U. Pandey

1999-01-01

371

Effect of gamma and laser radiations on the thermal properties of Makrofol nuclear track detector  

NASA Astrophysics Data System (ADS)

A study of the modification possibility of the thermal properties of Makrofol polycarbonate solid-state nuclear track detector using gamma and laser radiations has been carried out. Samples from 300 ?m thickness Makrofol sheets were classified into two main groups. The first group was irradiated with gamma doses at levels between 50 and 400 kGy, whereas the second group was exposed to infrared laser radiation with energy fluences at levels between 0.5 and 15 J/cm2. Non-isothermal studies were carried out using thermo-gravimetric analysis (TGA) to obtain the thermal activation energy of decomposition for the Makrofol detector. The results of TGA indicate that the Makrofol samples decompose in one main weight loss stage. Also, the irradiation of Makrofol polymer with gamma doses in the range 135-300 kGy or the exposure to laser energy fluences at levels between 8.3 and 15 J/cm2 leads to further enhancement of the thermal stability of the polymer samples due to the cross-linking phenomenon. This suggests that gamma radiation could be a suitable technique for producing a plastic material with enhanced properties that can be a useful candidate for high-temperature applications. In addition, the variation of transition temperatures with the gamma or laser doses has been determined using differential thermal analysis DTA. The results indicate that the irradiation with gamma in the dose range 50-135 kGy or the exposure to laser energy fluences at levels between 8.3 and 15 J/cm2 decreases the melting temperature of the Makrofol samples, and this is most suitable for applications requiring the molding of this polymer at lower temperatures.

Nouh, S. A.; Naby, A. Abdel

372

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

SciTech Connect

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

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

2006-11-02

373

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

SciTech Connect

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

Reniers, B.; Landry, G.; Eichner, R.; Hallil, A.; Verhaegen, F. [Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6229 ET (Netherlands); Best Medical Canada, Ottawa K2K 0E4 (Canada); Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6229 ET (Netherlands) and Medical Physics Unit, McGill University, Montreal General Hospital, Montreal, Quebec H3G 1A4 (Canada)

2012-04-15

374

(Hg,Zn)Te photon detectors of 10.6 micron laser radiation with optical resonance cavity  

NASA Astrophysics Data System (ADS)

The electric-field distributions of the light wave, radiation intensity, external quantum yield, and carrier concentration are determined in a photosensitive element located in an optical resonance cavity. Based on the results obtained, the normalized detectivity of a (Hg,Zn)Te photon detector is evaluated. It is shown that the interference effects in a homogeneous with respect to the energy gap and doping photosensitive element can result in the improvement of the detection parameters. High normalized detectivity is observed through numerical calculations in cooled and uncooled photoresistors, photomagnetoelectric detectors, and Dember detectors.

Niedziela, Tadeusz

1990-10-01

375

Transition radiation detectors for electron identification beyond 1 GeV/ c  

NASA Astrophysics Data System (ADS)

Transition radiation detectors (TRDs) have been tested for the separation of electrons from pions in the momentum range between 1 and 6 GeV/ c. Foams as well as fibres and foils served as radiator materials while two types of chambers, a longitudinal drift chamber (DC) and a multiwire proportional chamber (MWPC), both of 16 mm depth and dominantly filled with xenon, were used for detecting the transition radiation photons with a setup of four chambers. Analyzing the data we compared the methods of mean, truncated mean and of maximum likelihood of the total charge measurements and several methods of cluster analysis. As a result of the total charge measurements performed at test beams at CERN and DESY we obtained about 1% pion contamination at 90% electron efficiency for the polypropylene materials in the configuration of four modules with a total length of 40 cm. An improvement by a factor of about two for the electron/pion discrimination can be obtained in the case of a detailed analysis of the clusters.

Appuhn, R. D.; Heinloth, K.; Lange, E.; Oedingen, R.; Schlösser, A.

1988-01-01

376

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

377

Characterization of amorphous selenium alloy detectors for x-rays and high energy nuclear radiation detection  

NASA Astrophysics Data System (ADS)

Synthesized amorphous selenium (a-Se) alloy materials have been characterized for room temperature high-energy nuclear radiation detector and x-ray detection applications. The alloy composition has been optimized to ensure good charge transport properties and detector performance. The synthesis of a-Se (As, Cl) alloys has been carried out by thoroughly mixing zone-refined (ZR) Se (~7N) with previously synthesized a-Se(As) and a-Se(Cl) master alloys (MS). The synthesized alloys have been characterized by x-ray diffraction (XRD), glow discharge mass spectroscopy (GDMS), differential scanning calorimetry (DSC), x-ray photoelectron spectroscopy (XPS), and current-voltage (I-V) characteristics measurements. Raman spectroscopy demonstrated that the a-Se(As) master alloy samples were in metastable monoclinic Se8 states, in which seven vibrational modes are located at 40(41), 59(60), 77, 110, 133, 227(228) and 251(252) cm-1. However, a-Se(Cl) master alloy samples are in stable form of trigonal structure of Se8 ring, in which two modes at 142 and 234 cm-1 were found. Both Raman and energy dispersive spectroscopy (EDS) exhibited that a small amount of tellurium (Te) existed in a-Se (As, Cl) master alloy samples. DSC measurements showed that a-Se (Cl) MS and a-Se (As) MS samples have one melting point, located at ~219.6°C, whereas a-Se-As (0.52%)-Cl and Se- As(10.2%)-Cl(60 ppm) both possess two melting points, located at 221 and 220.3°C respectively. The a-Se alloy plate detectors have been fabricated and tested and the results showed high dark resistivity (1012 - 1013 ?-cm) with good charge transport properties and cost-effective large-area scalability.

Mandal, Krishna C.; Mehta, Abhinav; Chaudhuri, Sandeep K.; Cui, Yunlong; Groza, Michael; Burger, Arnold

2013-09-01

378

Vertical Bridgman growth of Cd 1-x Zn xTe for room temperature radiation detectors  

NASA Astrophysics Data System (ADS)

Low pressure Electro-Dynamic Gradient freeze (EDG) method has been used to grow compensated, high resistivity Cd(1-x)ZnxTe for x and gamma ray detectors. All growths contained excess Tellurium which is added to the growth. Ampoule design and setup to limit vapor transport was determined to be important. Ingots grown in a Pyrolitic Coated Graphite crucible are shown to provide a good response to ionizing radiation at room temperature and can be used multiple times. The highest doping levels of Aluminum are shown to improve mobility lifetime products for electrons and average 8.7x10 -4 cm2/V at 0.5 ?second shaping fitting the Hecht relation.

Jones, Kelly A.; Ciampi, Guido; Skrip, Christie E.; Lynn, K. G.

2007-09-01

379

Space situational awareness satellites and ground based radiation counting and imaging detector technology  

NASA Astrophysics Data System (ADS)

We review the current status from the scientific and technological point of view of solar energetic particles, solar and galactic cosmic ray measurements as well as high energy UV-, X- and gamma-ray imaging of the Sun. These particles and electromagnetic data are an important tool for space situational awareness (SSA) aspects like space weather storm predictions to avoid failures in space, air and ground based technological systems. Real time data acquisition, position and energy sensitive imaging are demanded by the international space weather forecast services. We present how newly developed, highly miniaturized radiation detectors can find application in space in view of future SSA related satellites as a novel space application due to their counting and imaging capabilities.

Jansen, Frank; Behrens, Jörg; Pospisil, Stanislav; Kudela, Karel

2011-05-01

380

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

DOEpatents

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

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

2000-01-01

381

A low-noise, low stored energy preamplifier for high-voltage radiation detectors  

NASA Astrophysics Data System (ADS)

A low-noise preamplifier with very low stored energy has been developed for use with high-voltage radiation detectors. The input will withstand 3.5 kV, has a physical capacitance to ground of 200 pF, and an effective "small signal" capacitance of ˜30 nF. When connected to a high-voltage electrode, the low physical input capacitance to ground limits the stored energy and helps protect the detector system should an accidental discharge occur. The large effective input capacitance minimizes the voltage transient on the high-voltage electrode that occurs during charge collection, thus lowering the charge that is capacitively coupled to surrounding electrodes from this transient. If the surrounding electrodes are part of a position sensing readout, then this coupled charge is distributed uniformly among readout electrodes and is added to the signal charge induced by the motion of charge carriers containing position information. This introduces an error into the position centroid calculation. The preamplifier presented here greatly reduces this effect while keeping stored energy low. Equivalent input noise charge (ENC) is 256 electrons RMS when using a 250 ns unipolar shaping amplifier and no input capacitance. With input capacitances of 18 and 223 pF, the noise increases to 361 and 1766 electrons RMS, respectively.

Harder, Joseph; Radeka, Veljko; Smith, Graham; Yu, Bo

2007-06-01

382

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

SciTech Connect

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

Gazizov, I. M., E-mail: gazizov@isotop.dubna.ru [Institute for Physico-Technical Problems (Russian Federation); Zaletin, V. M. [Dubna University (Russian Federation); Kukushkin, V. M.; Khrunov, V. S. [Institute for Physico-Technical Problems (Russian Federation)

2011-05-15

383

A new miniature microchannel plate X-ray detector for synchrotron radiation  

NASA Astrophysics Data System (ADS)

A state-of-the-art microchannel plate detector has been developed which allows real time X-ray imagin of X-ray diffraction as well as a radiographic phenomenon. Advantages of the device include a 50 mm X-ray input, length less than 4?, and a weight of less than 1 lb. Since the use of synchrotron radiation is greatly facilitated by the capability of remote viewing of X-ray diffraction or radiographic images in real time, a prototype electro-optical system has been designed which couples the X-ray microchannel plate detector with a solid state television camera. Advantages of the miniature, lightweight, X-ray synchroton camera include a large 50 mm X-ray input window, an output signal that is available in both analog format for display on a television monitor and in digital format for computer processing, and a completely modular design which allows all the components to be exchanged for other components optimally suited for the desired applications.

Rosemeier, Ronald G.; Green, Robert E.

384

Intraoperative radioimmunodetection of colorectal tumor with a hand-held radiation detector  

SciTech Connect

A hand-held gamma detection probe was used intraoperatively to localize primary and recurrent colorectal tumors in 28 patients 48 to 72 hours after they received an intravenous injection of 2.2 mCi of iodine-131 labeled anticarcinoembryonic antigen polyclonal baboon antibody. Preoperative evaluation included determination of serum carcinoembryonic antigen, barium enema, colonoscopy, chest film, computerized axial tomography, liver, spleen, and bone scans, and endoscopy when indicated. Preoperative whole-body imaging correctly localized primary tumors in only 33 percent of the patients, whereas it correctly demonstrated tumor in 64 percent of those with recurrent disease. Intraoperative tumor-to-background ratios derived from the detector probe were elevated in all patients, averaging 3.97:1 in primary lesions and 4.18:1 in recurrent tumors. Postoperatively, carcinoembryonic antigen was localized in tissues with the avidin-biotin peroxidase staining technique to confirm intraoperative readings. Variations in stain uptake in a patient could be correlated with variations in radiation detector readings in the same patient. Results support our previous work in nude mice, demonstrating the improved sensitivity and specificity of the hand-held gamma detection device over whole-body imaging for intraoperative localization of immunoradiolabeled tumors.

Martin, D.T.; Hinkle, G.H.; Tuttle, S.; Olsen, J.; Nabi, H.; Houchens, D.; Thurston, M.; Martin, E.W. Jr.

1985-12-01

385

Measurement of secondary radiation during ion beam therapy with the pixel detector Timepix  

NASA Astrophysics Data System (ADS)

In ion beam therapy the finite range of the ion beams in tissue and the presence of the Bragg-peak are exploited. Unpredictable changes in the patient`s condition can alter the range of the ion beam in the body. Therefore it is desired to verify the actual ion range during the treatment, preferably in a non-invasive way. Positron emission tomography (PET) has been used successfully to monitor the applied dose distributions. This method however suffers from limited applicability and low detection efficiency. In order to increase the detection efficiency and to decrease the uncertainties, in this study we investigate the possibility to measure secondary charged particles emerging from the patient during irradiation. An initial experimental study to register the particle radiation coming out of a patient phantom during the therapy was performed at the Heidelberg Ion Beam Therapy Center (HIT) in Germany. A static narrowly-focused beam of carbon ions was directed into a head phantom. The emerging secondary radiation was measured with the position-sensitive Timepix detector outside of the phantom. The detector, developed by the Medipix Collaboration, consists of a silicon sensor bump bonded to a pixelated readout chip (256 × 256 pixels with 55 ?m pitch). Together with the USB-based readout interface, Timepix can operate as an active nuclear emulsion registering single particles online with 2D-track visualization. In this contribution we measured the signal behind the head phantom and investigated its dependence on the beam energy (corresponding to beam range in water 2-30 cm). Furthermore, the response was measured at four angles between 0 and 90 degrees. At all investigated energies some signal was registered. Its pattern corresponds to ions. Differences in the total amount of signal for different beam energies were observed. The time-structure of the signal is correlated with that of the incoming beam, showing that we register products of prompt processes. Such measurements are less likely to be influenced by biological washout processes than the signal registered by the PET technique, coming from decays of beam-induced radioactive nuclei. This work demonstrates that the Timepix detector is able to register ions emerging from the patient during the treatment by carbon ion beams. In future work it will be investigated which information about the incoming beam can be gained from the analysis of the measured data.

Martišíková, Mária; Jakubek, Jan; Granja, Carlos; Hartmann, Bernadette; Opálka, Lukáš; Pospíšil, Stanislav; Jäkel, Oliver

2011-11-01

386

Alpha Particle Time of Flight Measurements on a new class of CdZnTe Radiation Detectors.  

National Technical Information Service (NTIS)

A time of flight technique was used to study the carrier trapping time, t, and mobility, in various CdZnTe (CZT) radiation detectors. A new class of CZT crystals doped with various elements, grown by a modified Bridgman method at Yirmel Tech, were fabrica...

J. C. Erickson H. W. Yao R. B. James R. Olsen L. Li F. Lu

2000-01-01

387

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

SciTech Connect

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

Hutton, R.D.

1994-01-01

388

Structural properties of cadmium zinc telluride and their effects on nuclear radiation detector performance  

NASA Astrophysics Data System (ADS)

Structural properties of cadmium zinc telluride, Cdsb{1-x}Znsb{x}Te, used as room temperature nuclear radiation detectors are characterized in relation to various detector properties. Alloy (zinc) composition variation is determined by triple axis diffraction lattice parameter measurements and its effects on the material resistivity are examined. Structural defects including cracks, grain/twin boundaries, mosaic structure, small angle tilt boundaries, and dislocations are characterized and correlated to leakage current and electron charge collection efficiency (esp-CCE). The segregation coefficient of zinc in high pressure Bridgman grown Cdsb{1-x}Znsb{x}Te (x ˜\\ 0.1) was determined for the first time to be k = 1.15, compared to k = 1.3, a commonly accepted value for Cdsb{1-x}Znsb{x}Te (x\\ ˜\\ 0.04), indicating a more uniform distribution of zinc throughout the ingot. The systematic increase in the resistivity of the material with higher zinc content is not observed experimentally, clearly indicating that the resistivity is governed by extrinsic properties. From structural defect investigations, it is shown that cracks lead to unacceptably large leakage currents and grain boundaries are found to lower the esp-CCE by serving as charge recombination sites. Furthermore, the more subtle structural defects such as mosaic structure, small angle tilt boundaries, and dislocations that lower the crystalline perfection of single crystal Cdsb{1-x}Znsb{x}Te are also shown to lower the esp-CCE. Crystal regions exhibiting triple axis x-ray diffraction (TAD) omega-scan full width at half maximum (FWHM) values of > ˜40 arcsecs typically had etch pit density (EPD) of ˜10sp5 cmsp{-2}, while regions exhibiting FWHM of <10 arcsecs typically had EPD of ˜10sp4 cmsp{-2}. Double crystal x-ray topography images confirmed the TAD results and revealed the spatial locations of the tilt boundaries. Poor crystal quality regions are shown to always correlate with lower esp-CCE, but regions of high crystal quality are found to exhibit both high and low esp-CCE, suggesting that chemical imperfections can play a dominant role in the detector response. These findings provide a better understanding of the crystalline structure, defects, and the zinc composition variation in Cdsb{1-x}Znsb{x}Te, and their influence on various detector-related properties.

Yoon, Hojun

389

Correlation between radiation processes in silicon and long-time degradation of detectors for high-energy physics experiments  

NASA Astrophysics Data System (ADS)

In this contribution, the correlation between fundamental interaction processes induced by radiation in silicon and observable effects which limit the use of silicon detectors in high-energy physics experiments is investigated in the frame of a phenomenological model which includes: generation of primary defects at irradiation, starting from elementary interactions in silicon; kinetics of defects, effects at the p-n junction detector level. The effects due to irradiating particles (pions, protons, neutrons), to their flux, to the anisotropy of the threshold energy in silicon, to the impurity concentrations and resistivity of the starting material are investigated as time, fluence and temperature dependences of detector characteristics. The expected degradation of the electrical parameters of detectors in the complex hadron background fields at LHC & SLHC is predicted.

Lazanu, Sorina; Lazanu, Ionel

2007-09-01

390

Recent results of CERN RD39 collaboration on development of radiation hard Si detectors operated at low to cryogenic temperatures  

NASA Astrophysics Data System (ADS)

Recent results of CERN RD39 collaboration on the development of radiation hard Si detectors operated at low to cryogenic temperatures will be presented in this paper. It has been found, in comparisons of results of simulation and charge collection data of pad and strip detectors, the charge-injected-diode (CID) operation mode of Si detectors reduces the free carrier trapping, resulting in a much higher charge collection at the SLHC fluence than that in a standard Si detector. The reduction in free carrier trapping by almost a factor of 3 is due to the fact that the CID mode pre-fills the traps, making them neutral and not active in trapping of particle-induced free carriers (signal). It has been found that, electron traps can be pre-filled by injection of electrons from the n+ contact. The CID mode of detector operation can be achieved by a modestly low temperature of ?-40 °C and a operation bias of <600 V. Results of one CID detector application as LHC beam-loss-monitor (BLM) will be presented. Non-irradiated Si detectors has been shown, with tests by laser using our cryogenic transient-current-technique (TCT), to work quite well at LHe temperature (4 K), which are very stable with no polarization and good charge collection efficiency.

Li, Zheng; Chen, W.; Eremin, V.; Ha¨rko¨nen, J.; Luukka, P.; Tuominen, E.; Tuovinen, E.; Verbitskaya, E.

2013-08-01

391

Radiation hardness studies of CdTe thin films for clinical high-energy photon beam detectors  

NASA Astrophysics Data System (ADS)

In radiation oncology applications, the need for higher-quality images has been driven by recent advances in radiation delivery systems that require online imaging. The existing electronic imaging devices commonly used to acquire portal images implement amorphous silicon (a-Si) detector, which exhibits poor image quality. Efforts for improvement have mostly been in the areas of noise and scatter reduction through software. This has not been successful due to inherent shortcomings of a-Si material. Cadmium telluride (CdTe) semiconductor has long been recognized as highly suitable for use in X-ray detectors in both spectroscopic and imaging applications. Development of such systems has mostly concentrated on single crystal CdTe. Recent advances in thin-film deposition technology suggest replacement of crystalline material with its polycrystalline counterpart, offering ease of large-area device fabrication and achievement of higher resolution as well as a favorable cost difference. While bulk CdTe material was found to have superior radiation hardness, thin films have not been evaluated from that prospective, in particular under high-energy photon beam typical of radiation treatment applications. We assess the performance of thin-film CdTe devices utilizing 6 MeV photon beam and find no consistent trend for material degradation under doses far exceeding the typical radiation therapy detector lifetime dose.

Shvydka, Diana; Parsai, E. I.; Kang, J.

2008-02-01

392

R&D studies of a RICH detector using pressurized C4F8O radiator gas and a CsI-based gaseous photon detector  

NASA Astrophysics Data System (ADS)

We report on studies of layout and performance of a new Ring Imaging Cherenkov detector using for the first time pressurized C4F8O radiator gas and a photon detector consisting of a MWPC equipped with a CsI photocathode. In particular, we present here the results of beam tests of a MWPC having an adjustable anode-cathode gap, aiming at the optimization of single photoelectron detection and Cherenkov angle resolution. This system was proposed as a Very High Momentum Particle Identification (VHMPID) upgrade for the ALICE experiment at LHC to provide charged hadron track-by-track identification in the momentum range 5-25 GeV/c.

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

2013-12-01

393

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

SciTech Connect

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

Goma, Carles; Ruiz, Agustin; Jornet, Nuria; Latorre, Artur; Pallerol, Rosa M.; Carrasco, Pablo; Eudaldo, Teresa; Ribas, Montserrat [Servei de Radiofisica i Radioproteccio, Hospital de la Santa Creu i Sant Pau, Sant Antoni Maria Claret 167, 08025 Barcelona (Spain)

2011-03-15

394

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

NASA Astrophysics Data System (ADS)

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

Smith, Holland McTyeire

395

Implementation of a preamplifier-amplifier system for radiation detectors used in Mössbauer spectroscopy  

NASA Astrophysics Data System (ADS)

We report the assembly and testing of a preamplification and amplification system for pulses produced by gaseous radiation detectors commonly used in Mössbauer spectroscopy. The system is composed by a pair of commercial integrated circuits A203 and A206, which operate as charge sensitive preamplifier-shaping amplifier and linear amplifier-low level discriminator, respectively. The integrated circuits were interconnected in the unipolar output mode and placed inside a metallic shielding, which prevents noise amplification for a suitable signal-noise ratio. The system was tested by irradiating a proportional counter LND-45431 with characteristic X rays of 6.3 keV and gamma rays of 14.4 keV emitted by a Mössbauer radioactive source of 57Co (Rh). Unipolar pulses with Gaussian profile were obtained at the output of the linear amplifier, whose amplitudes were close to 0.4 V for 6.3 keV X rays and 1.4 V for 14.4 keV gamma rays. Pulse height spectra showed that the system allows a satisfactory identification of the X-rays and gamma rays emitted by the 57Co source, giving the possibility to make a good selection of the 14.4 keV peak for having a suitable signal-noise ratio in the Mössbauer spectra. Absorption percentages of 14 % were found by taking the Mössbauer spectra of a natural iron absorber. The assembly and tests of the system are presented through this paper.

Velásquez, A. A.; Arroyave, M.

2014-01-01

396

Some Digital Techniques for Real Time Processing of Pulses from Radiation Detectors.  

NASA Astrophysics Data System (ADS)

Digital methods for processing pulses from radiation detectors have been investigated. A processor with improved differential linearity, which implements a moving average technique has been designed. A threshold free approach for peak-detection has been developed. The circuit also provides a timing signal with uncertainty of one sampling period. Techniques have been developed for the synthesis of pulse shapes using fast digital schemes in place of the traditional analog methods of pulse shaping. Efficient recursive algorithms have been developed that allow real time implementation of a shaper that can produce either trapezoidal or triangular pulse shapes. Other recursive techniques are presented which allow a synthesis of finite cusp-like shapes. Experimental tests show potential advantages of using these techniques in high-resolution, high counting rate pulse-height spectroscopy. A digital method for pulse -shape analysis has been developed. Near-optimum weighting function is used for processing digital samples of the signal from a gated integrator. A figure of merit for neutron-gamma pulse-shape discrimination was found to be: 0.78 for 25 keV (electron equivalent) and 3.5 for 500 keV.

Jordanov, Valentin T.

1994-01-01

397

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

DOEpatents

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

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

2012-09-04

398

Gamma Radiation Detectors of the TA-55 Waste Line Monitoring System  

SciTech Connect

This report covers the gamma detectors, measurement instrumentation, and testing results of a system developed at Los Alamos National Laboratory. This system monitors the process liquid waste streams at the Plutonium Facility (TA-55) for the presence of radioactive contamination. The detectors are at various points on the acid, caustic, and industrial waste lines. Two of the detectors are on the sanitary sewer lines from the facility. A custom interface unit associated with these two detectors furnishes the facility operation center with a notification of the detection of material. All of the detectors furnish measurement information to a central computer system for storage and trending.

Jack E. Malcom

1999-06-01

399

Electric Field and Current Transport Mechanisms in Schottky CdTe X-ray Detectors under Perturbing Optical Radiation  

PubMed Central

Schottky CdTe X-ray detectors exhibit excellent spectroscopic performance but suffer from instabilities. Hence it is of extreme relevance to investigate their electrical properties. A systematic study of the electric field distribution and the current flowing in such detectors under optical perturbations is presented here. The detector response is explored by varying experimental parameters, such as voltage, temperature, and radiation wavelength. The strongest perturbation is observed under 850 nm irradiation, bulk carrier recombination becoming effective there. Cathode and anode irradiations evidence the crucial role of the contacts, the cathode being Ohmic and the anode blocking. In particular, under irradiation of the cathode, charge injection occurs and peculiar kinks, typical of trap filling, are observed both in the current-voltage characteristic and during transients. The simultaneous access to the electric field and the current highlights the correlation between free and fixed charges, and unveils carrier transport/collection mechanisms otherwise hidden.

Cola, Adriano; Farella, Isabella

2013-01-01

400

Performance, high voltage operation and radiation hardness of full-size ATLAS charge division silicon detectors with LHC electronics  

NASA Astrophysics Data System (ADS)

ATLAS silicon detectors designed for charge division read-out were produced during 1995 and have been extensively studied both in the laboratory and test beam at the CERN SPS. Data have been taken with the analogue read-out FELIX-128 chip and studies simulating other read-out architectures under consideration by ATLAS have been performed. To evaluate survival in the harsh environment of the LHC, detectors have been tested to high voltage, both before and after radiation damage by protons exceeding the expected charged hadron dose after 10 years of LHC operation. These tests have all employed analogue read-out to be sensitive to changes in noise and charge collection efficiency as a function of the detector damage.

Allport, P. P.; Booth, P. S. L.; Carter, J. R.; Goodrick, M. J.; Green, C.; Greenall, A.; Hanlon, M.; Hill, J. C.; Jackson, J. N.; Jones, T. J.; Martí i García, S.; Munday, D. J.; Murray, W.; Richardson, J. D.; Robinson, D.; Sheridan, A. E.; Smith, N. A.; Tyndel, M.; Wyllie, K.

1998-02-01

401

Performance, high voltage operation and radiation hardness of full-size ATLAS charge division silicon detectors with LHC electronics  

NASA Astrophysics Data System (ADS)

ATLAS silicon detectors designed for charge division read-out were produced during 1995 and have been extensively studied both in the laboratory and test beam at the CERN SPS. Data have been taken with the analogue read-out FELIX-128 chip and studies simulating other read-out architectures under consideration by ATLAS have been performed. To evaluate survival in the harsh environment of the LHC, detectors have been tested to high voltage, both before and after radiation damage by protons exceeding the expected charged hadron dose after 10 years of LHC operation. These tests have all employed analogue read-out to be sensitive to changes in noise and charge collection efficiency as a function of the detector damage.

Allport, P. P.; Booth, P. S. L.; Carter, J. R.; Goodrick, M. J.; Green, C.; Greenall, A.; Hanlon, M.; Hill, J. C.; Jackson, J. N.; Jones, T. J.; Martí I García, S.; Munday, D. J.; Murray, W.; Richardson, J. D.; Robinson, D.; Sheridan, A. E.; Smith, N. A.; Tyndel, M.; Wyllie, K.

1997-02-01

402

Radiation damage effects by electrons, protons, and neutrons in Si/Li/ detectors.  

NASA Technical Reports Server (NTRS)

The degradation in performance of lithium-compensated silicon nuclear particle detectors induced by irradiation at room temperature with 0.6-MeV and 1.5-MeV electrons, 1.9-MeV protons, and fast neutrons from a plutonium-beryllium source has been investigated. With increasing fluence, the irradiations produced an increase of detector leakage current, noise, capacitance, and a degradation in the performance of the detector as a charged-particle energy spectrometer. Following the irradiations, annealing effects were observed when the detectors were reverse-biased at their recommended operating voltages. Upon removal of bias, a continuous degradation of detector performance characteristics occurred. Detectors which had been damaged by electrons and protons exhibited a stabilization in their characteristics within two weeks after irradiation, whereas detectors damaged by neutrons had a continuous degradation of performance over a period of several months.

Liu, Y. M.; Coleman, J. A.

1972-01-01

403

Radiation hardness of a polycrystalline chemical-vapor-deposited diamond detector irradiated with 14 MeV neutrons  

NASA Astrophysics Data System (ADS)

Chemical-vapor-deposited (CVD) diamond films are considered as neutron detectors for nuclear fusion devices because of their radiation hardness. Data about the radiation hardness of polycrystalline CVD diamond films exposed to 14 MeV neutron are missing in literature so the actual capability of CVD diamond detectors to withstand fusion device conditions must be truly demonstrated. In this work a polycrystalline CVD diamond detector, 101 ?m thick, was irradiated for the first time with 14 MeV neutrons produced by the Fusion Neutron Source of the Japan Atomic Energy Research Institute with the goal to study its radiation hardness. The 14 MeV neutron fluence was 8×1014 n/cm2. The film performances were studied before and after the 14 MeV neutron irradiation by using 5.5 MeV ? from 241Am source, both in the pumped and the ``as-grown'' state. A comparison with previous measurements performed in more soft neutron spectra (mean neutron energy of 1-2 MeV) is reported pointing out the more damaging effects of the 14 MeV neutrons. It was found that annealing at 500 °C and redeposition of the gold contact followed by a proper pumping procedure will restore more than 70% the initial working conditions of the irradiated detector. An analysis of the neutron field expected in the neutron camera of the International Thermonuclear Reactor fusion tokamak was also performed, showing the capability of CVD diamond detector to withstand the 14 MeV neutron fluence expected in about one year of operation.

Angelone, M.; Pillon, M.; Balducci, A.; Marinelli, M.; Milani, E.; Morgada, M. E.; Pucella, G.; Tucciarone, A.; Verona-Rinati, G.; Ochiai, Kentaro; Nishitani, Takeo

2006-02-01

404

Radiation hardness of a polycrystalline chemical-vapor-deposited diamond detector irradiated with 14 MeV neutrons  

SciTech Connect

Chemical-vapor-deposited (CVD) diamond films are considered as neutron detectors for nuclear fusion devices because of their radiation hardness. Data about the radiation hardness of polycrystalline CVD diamond films exposed to 14 MeV neutron are missing in literature so the actual capability of CVD diamond detectors to withstand fusion device conditions must be truly demonstrated. In this work a polycrystalline CVD diamond detector, 101 {mu}m thick, was irradiated for the first time with 14 MeV neutrons produced by the Fusion Neutron Source of the Japan Atomic Energy Research Institute with the goal to study its radiation hardness. The 14 MeV neutron fluence was 8x10{sup 14} n/cm{sup 2}. The film performances were studied before and after the 14 MeV neutron irradiation by using 5.5 MeV {alpha} from {sup 241}Am source, both in the pumped and the 'as-grown' state. A comparison with previous measurements performed in more soft neutron spectra (mean neutron energy of 1-2 MeV) is reported pointing out the more damaging effects of the 14 MeV neutrons. It was found that annealing at 500 deg. C and redeposition of the gold contact followed by a proper pumping procedure will restore more than 70% the initial working conditions of the irradiated detector. An analysis of the neutron field expected in the neutron camera of the International Thermonuclear Reactor fusion tokamak was also performed, showing the capability of CVD diamond detector to withstand the 14 MeV neutron fluence expected in about one year of operation.

Angelone, M.; Pillon, M.; Balducci, A.; Marinelli, M.; Milani, E.; Morgada, M.E.; Pucella, G.; Tucciarone, A.; Verona-Rinati, G.; Ochiai, Kentaro; Nishitani, Takeo [Associazione EURATOM-ENEA sulla Fusione, Centro Ricerche Frascati, via E. Fermi 45, I-00044 Frascati, Roma (Italy); INFM-Dipartimento di Ingegneria Meccanica, Universita di Roma 'Tor Vergata', via del Politecnico 1, I-00133 Rome (Italy); Department of Fusion Engineering Research, Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 (Japan)

2006-02-15

405

High rate, high resolution, two-dimensional gas proportional detectors for x-ray synchrotron radiation experiments  

SciTech Connect

Two-dimensional, gas proportional detectors are being developed for use with X-ray synchrotron radiation. Two new types of interpolating cathode structures have been investigated, both of which can operate with a significantly smaller number of readout nodes along each sensing axis than previous cathodes. Lumped parameter delay lines are used as the position encoders. Timing signals from fast, low noise shaping electronics are fed to a new, dual TDC system developed for this purpose. Operating with a clock frequency of 500 MHz, the TDCs have an intrinsic differential non-linearity of 0.1%. The complete system can handle X-ray fluxes in excess of 10{sup 6} per sec without distortion of the position information. A resolution of approximately 100 {mu}m FWHM and differenfial non-linearity of {plus minus}4% have been achieved. Application of a detector with active area 10 cm {times} 10 cm using synchrotron radiation is described.

Smith, G.C.; Yu, B.; Fischer, J.; Radeka, V.; Harder, J.A.

1992-02-01

406

Thermoluminescent detectors applied in individual monitoring of radiation workers in Europe--a review based on the EURADOS questionnaire.  

PubMed

Among the activities of EURADOS Working Group 2 formed by experts from several European countries is the harmonisation of individual monitoring as part of radiation protection of occupationally exposed persons. Here, we provide information about thermoluminescent detectors (TLDs) applied by the European dosimetric services and the dosimetric characteristics of dosemeters in which these detectors are applied. Among 91 services from 29 countries which responded to the EURADOS questionnaire, 61 apply dosemeters with TLDs for the determination of personal dose equivalent H(p)(10) for photons and beta radiation, and 16 services use TLDs for neutron albedo dosemeters. Those most frequently used are standard lithium fluoride TLDs (mainly TLD-100, TLD-700, Polish MTS-N and MTS-7, Russian DTG-4), high-sensitive lithium fluoride (GR-200, MCP-N) and lithium borate TLDs. Some services use calcium sulphate and calcium fluoride detectors. For neutron dosimetry, most services apply pairs of LiF:Mg,Ti TLDs with (6)Li and (7)Li. The characteristics (energy response) of individual dosemeters are mainly related to the energy response of the detectors and filters applied. The construction of filters in dosemeters applied for measurements of H(p)(10) and their energy response are also reviewed. PMID:16581929

Olko, P; Currivan, L; van Dijk, J W E; Lopez, M A; Wernli, C

2006-01-01

407

Reduced leakage currents of CdZnTe radiation detectors with HgTe/HgCdTe superlattice contacts  

NASA Astrophysics Data System (ADS)

Room-temperature-operating CdZnTe radiation detectors have high energy resolution, linear energy response and are capable of operating in normal counting and spectroscopic modes, hence are highly desirable for medical diagnosis, nondestructive industrial evaluations, homeland security, counterterrorism inspections and nuclear proliferation detection to ensure national and international nuclear safety. HgTe/HgCdTe superlattices can be designed to selectively transport one carrier species while hindering transport of the other. Specifically, one designs a large carrier effective mass for undesired carriers in the electric field direction, which results in low carrier velocities, and yet a density of states for undesired carrier that is lower than that of a comparable bulk semiconductor, which results in low carrier concentrations, hence a low current density under an electric field. The opposite carrier species can be designed to have a large velocity and high density of states, hence producing a large current density. By employing HgTe/HgCdTe superlattices as contact layers intermediate between CdZnTe absorbers and metal contacts, leakage currents under high electric fields are reduced and improved x-ray and ?-ray detector performance is anticipated. Pixilated CdZnTe radiation detectors arrays were fabricated and characterized to evaluate the effectiveness of HgTe/HgCdTe superlattices in reducing leakage currents. Current-voltage characteristics show that HgTe/HgCdTe superlattice contact layers consistently result in significantly reduced leakage currents relative to detectors with only metal contacts.

Chang, Y.; Grein, C. H.; Becker, C. R.; Huang, J.; Ghosh, S.; Aqariden, F.; Sivananthan, S.

2012-10-01

408

Metal micro-detector TimePix imaging synchrotron radiation beams at the ESRF Bio-Medical Beamline ID17  

NASA Astrophysics Data System (ADS)

Characterization studies of the metal micro-detector TimePix measuring dose distribution at the Minibeam Radiation Therapy setup (Bio-Medical Beamline ID17, ESRF) were performed. The results obtained for high intensity synchrotron radiation minibeams illustrate an excellent performance of the TimePix providing in real time 2D image of the dose distribution over many beams in a 14×14 mm2 area. Peak-to-Valley-Dose-Ratios measured by TimePix and gafhromic films agree well.

Pugatch, V.; Campbell, M.; Chaus, A.; Kovalchuk, O.; Llopart, X.; Okhrimenko, O.; Pospisil, S.; Prezado, Y.; Renier, M.; Tlustos, L.

2012-08-01

409

Radiation hardness perspectives for the design of analog detector readout circuits in the 0.18-?m CMOS generation  

Microsoft Academic Search

This paper presents a study of the ionizing radiation tolerance of analog parameters of 0.18-?m CMOS transistors, in view of the application to the design of front-end integrated circuits for detectors in high-energy physics experiments. Static, signal, and noise performances of devices with various gate dimensions were monitored before and after irradiation up to a 300-kGy(Si) total dose of 60Co

Massimo Manghisoni; Lodovico Ratti; Valerio Re; Valeria Speziali

2002-01-01

410

Generation and detection of high-speed pulses of mid-infrared radiation with intersubband semiconductor lasers and detectors  

Microsoft Academic Search

Semiconductor lasers and detectors based on intersubband electron transitions are used to generate and measure high-speed pulses of mid-infrared radiation. In particular, we use a commercial comb generator to gain-switch a state-of-the-art 8-?m quantum cascade laser mounted in a high-speed package. The output pulses of this device are then detected with a small-area quantum-well infrared photodetector, also packaged for high-speed

Roberto Paiella; Federico Capasso; Claire Gmachl; Clyde G. Bethea; Deborah L. Sivco; James N. Baillargeon; Albert L. Hutchinson; Alfred Y. Cho; H. C. Liu

2000-01-01

411

Defect correlation studies on 4H-SiC crystals and epitaxial layers for radiation detector applications  

Microsoft Academic Search

Nuclear radiation detectors in the energy range of soft x-rays have been fabricated using bulk semi-insulating (SI) 4H-SiC crystals and SI and n-type 4H-SiC epitaxial layers grown by chemical vapor deposition (CVD) on highly doped (0001) 4H-SiC substrates. The devices have been characterized by optical microscopy, current-voltage (I-V) measurements, thermally stimulated current (TSC) spectroscopy (94K – 650 K), Hall effect,

Krishna C. Mandal; Peter G. Muzykov; Ramesh M. Krishna; Timothy C. Hayes

2011-01-01

412

Evaluation of the neutron radiation environment inside the International Space Station based on the Bonner Ball Neutron Detector experiment  

Microsoft Academic Search

The Bonner Ball Neutron Detector (BBND) experiment was conducted onboard the US Laboratory Module of the International Space Station (ISS) as part of the Human Research Facility project of NASA in order to evaluate the neutron radiation environment in the energy range from thermal up to 15MeV inside the ISS. The BBND experiment was carried out over an eight-month period

H. Koshiishi; H. Matsumoto; A. Chishiki; T. Goka; T. Omodaka

2007-01-01

413

Gamma radiation induced space charge sign inversion and re-inversion in p-type MCZ Si detectors and in proton-irradiated n-type MCZ Si detectors  

NASA Astrophysics Data System (ADS)

Positive space charge build-up was observed in proton—and neutron—irradiated high-resistivity magnetic Czochralski (MCZ) n-type Si detectors after gamma radiation. Space charge sign re-inversion (SCSRI) from negative to positive was achieved at the high dose of 454 Mrad in a low-fluence proton irradiated MCZ Si detector. No SCSRI has been observed yet for low-fluence neutron-irradiated MCZ Si detectors at the highest dose in this study (662 Mrad), but positive space charge is building up, and SCSRI is expected at higher doses. Up to the highest dose in this study, the double junction or double peak electric field distribution is still preserved even after SCSRI. No SCSRI was observed in control FZ Si detectors. Space charge sign inversion was also observed in high-resistivity as-processed MCZ p-type Si detectors after gamma radiation.

Li, Z.; Bruzzi, M.; Eremin, V.; Harkonen, J.; Kierstead, J.; Luukka, P.; Menichelli, D.; Tuominen; Tuovinen, E.; Verbitskaya, E.

2005-10-01

414

Fabrication and characterization of Cd0.9Zn0.1Te Schottky diodes for nuclear radiation detectors  

NASA Astrophysics Data System (ADS)

We have fabricated and characterized cadmium zinc telluride (CZT) Schottky diodes with low reverse leakage current for high resolution radiation detector applications. The diodes were made using Cd0.9Zn0.1Te detector grade crystals grown by the low temperature tellurium solvent method. The diodes were characterized using electron beam induced current (EBIC) technique to investigate crystallographic defects. The EBIC images were correlated with transmission infrared (TIR) images of CZT crystals and the EBIC contrast was attributed to the nonuniformities in spatial distribution of Te. Further characterization by the thermally stimulated current (TSC) spectroscopy revealed shallow and deep level centers with activation energies 0.25- 0.4 eV and 0.65 - 0.8 eV respectively, which we attribute to intrinsic defects associated with excess of Te. Pulse height spectra (PHS) measurements were carried out using a 241Am (59.6 keV) radiation source on the Frisch collar radiation detectors made from the suitable portions of the CZT ingot used for Schottky diode fabrication, and an energy resolution of ~4.2% FWHM was obtained.

Mandal, Krishna C.; Muzykov, Peter G.; Krishna, Ramesh M.; Hayes, Timothy C.

2011-09-01

415

A semi-analytic approximation of charge induction in monolithic pixelated CdZnTe radiation detectors  

NASA Astrophysics Data System (ADS)

A semi-analytic approximation to the weighting potential within monolithic pixelated CdZnTe radiation detectors is presented. The approximation is based on solving the multi-dimensional Laplace equation that results upon replacing rectangular pixels with equal-area circular pixels. Further, we utilize the simplicity of the resulting approximate weighting potential to extend the well-known Hecht equation, describing charge induction in a parallel plate detector, to that approximating the multi-dimensional charge induction within a pixelated detector. These newly found expressions for the weighting potential and charge induction in a pixelated detector are compared throughout to full 3D electrostatic and monte carlo simulations using eV DSIM ( eV Microelectronics Device SIMulator). The semi-analytic expressions derived in this paper can be evaluated quickly, and can therefore be used to efficiently reduce the size and dimensionality of the parameter space on which a detailed 3D numerical analysis is needed for pixelated detector design in a wide range of applications.

Bale, Derek S.

2010-03-01

416

Fine-scale spatial response of CdZnTe radiation detectors  

SciTech Connect

Several studies have suggested that the uniformity of Cadmium Zinc Telluride (CZT) detectors play an important role in their performance when operated as gamma-ray spectrometers. However the detailed gamma response of simple planar detectors as a function of position over the device area is largely unknown. To address this issue the authors have built a system capable of measuring the detector response with a resolution of {approximately}250 {micro}m. The system consists of a highly collimated ({approximately}200 {micro}m) photon source (<150 kev) scanned over the detector using a computer controlled two-axis translation stage. Fifteen samples configured as planar detectors were examined with the new apparatus. The material grade of the detectors examined varied from counter to select discriminator. Two classes of spatial response variation were observed and are presented here. Infrared (IR) transmission images were also acquired for each sample and correlation between features in the pulse height spectrum and crystalline defects were observed.

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

1998-11-07

417

The effect of background radiation on the characteristics of a Josephson detector  

NASA Astrophysics Data System (ADS)

Josephson point-contact detectors can be used to make radio-astronomical measurements of centimeter and millimeter waves. This paper presents an experimental study of the effect of background noise on the characteristics of such a detector. A reduction of the noise temperature from about 300 K to about 10 K significantly improves the sensitivity of the detector. The experimental results agree well with theoretical calculations.

Ilin, V. A.; Shurminova, T. M.; Etkin, V. S.

1981-08-01