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1

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

2

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

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

Radiation Detectors and Art  

NASA Astrophysics Data System (ADS)

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

Denker, Andrea

5

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

6

Photovoltaic radiation detector element  

DOEpatents

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

Agouridis, D.C.

1980-12-17

7

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

8

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

9

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

10

Gaseous Radiation Detectors  

NASA Astrophysics Data System (ADS)

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

Sauli, Fabio

2014-06-01

11

Broadband optical radiation detector  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

12

Radiation energy detector and analyzer  

SciTech Connect

A radiation detector array and a method for measuring the spectral content of radiation. The radiation sensor or detector is an array or stack of thin solid-electrolyte batteries. The batteries, arranged in a stack, may be composed of independent battery cells or may be arranged so that adjacent cells share a common terminal surface. This common surface is possible since the polarity of the batteries with respect to an adjacent battery is unrestricted, allowing a reduction in component parts of the assembly and reducing the overall stack length. Additionally, a test jig or chamber for allowing rapid measurement of the voltage across each battery is disclosed. A multichannel recorder and display may be used to indicate the voltage gradient change across the cells, or a small computer may be used for rapidly converting these voltage readings to a graph of radiation intensity versus wavelength or energy. The behavior of the batteries when used as a radiation detector and analyzer are such that the voltage measurements can be made at leisure after the detector array has been exposed to the radiation, and it is not necessary to make rapid measurements as is now done.

Roberts, T.G.

1981-09-15

13

Cadmium telluride photovoltaic radiation detector  

DOEpatents

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

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

1981-01-01

14

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

15

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

16

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

17

Radiation detectors as surveillance monitors  

SciTech Connect

The International Atomic Energy Agency (IAEA) proposes to use personnel dosimetry radiation detectors as surveillance monitors for safeguards purposes. It plans to place these YES/NO monitors at barrier penetration points declared closed under IAEA safeguards to detect the passage of plutonium-bearing nuclear material, usually spent fuel. For this application, commercially available dosimeters were surveyed as well as other radiation detectors that appeared suitable and likely to be marketed in the near future. No primary advantage was found in a particular detector type because in this application backgrounds vary during long counting intervals. Secondary considerations specify that the monitor be inexpensive and easy to tamper-proof, interrogate, and maintain. On this basis radiophotoluminescent, thermoluminescent, and electronic dosimeters were selected as possible routine monitors; the latter two may prove useful for data-base acquisition.

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

1981-01-01

18

Plasma Panel Based Radiation Detectors  

SciTech Connect

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

Friedman, Dr. Peter S. [Integrated Sensors, LLC; Varner Jr, Robert L [ORNL; Ball, Robert [University of Michigan; Beene, James R [ORNL; Ben Moshe, M. [Tel Aviv University; Benhammou, Yan [Tel Aviv University; Chapman, J. Wehrley [University of Michigan; Etzion, E [Tel Aviv University; Ferretti, Claudio [University of Michigan; Bentefour, E [Ion Beam Applications; Levin, Daniel S. [University of Michigan; Moshe, M. [Tel Aviv University; Silver, Yiftah [Tel Aviv University; Weaverdyck, Curtis [University of Michigan; Zhou, Bing [University of Michigan

2013-01-01

19

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

20

Solid State Detectors for High Radiation Environments  

NASA Astrophysics Data System (ADS)

This document is part of Part 2 'Principles and Methods' of Subvolume B 'Detectors for Particles and Radiation' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the Section '7.2 Solid State Detectors for High Radiation Environments' of Chapter '7 Applications of Detectors in Technology; Medicine and Other Fields' with the content:

Kramberger, G.

21

Device for calibrating a radiation detector system  

SciTech Connect

The present invention relates to a device for calibrating a radiation detector system that is used for measuring the radionuclide intake of those exposed to radioactive materials. In particular, the present invention relates to a device that simulates a human chest and lungs with a modicum of internal radiation for use in calibrating radiation detectors.

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

1993-09-23

22

49 CFR 173.310 - Exceptions for radiation detectors.  

Code of Federal Regulations, 2012 CFR

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

2012-10-01

23

49 CFR 173.310 - Exceptions for radiation detectors.  

Code of Federal Regulations, 2013 CFR

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

2013-10-01

24

49 CFR 173.310 - Exceptions for radiation detectors.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

25

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

26

Infrared receiver having a cooled radiation detector  

Microsoft Academic Search

An infrared receiver having an infrared radiation detector cooled by means of a cold-gas engine, the thermal contact between a cooling surface of the cold-gas engine and the radiation detector being obtained by an elastic thermally conducting bridge. The cylindrical bridge is comprised of a plurality of turns of a metal strip. Due to the presence of the bridge, a

Van Antwerpen

1985-01-01

27

Development of a plasma panel radiation detector  

E-print Network

This article reports on an investigation of a radiation detector based on plasma display panel technology. The plasma panel sensor (PPS) is a variant of micropattern gas radiation detectors. PPS components are non-reactive and intrinsically radiation-hard materials, such as glass substrates, metal electrodes and inert gas mixtures. Plasma display panels used as detectors were tested with cosmic ray muons, beta rays and gamma rays, protons, and thermal neutrons. The results demonstrated risetimes and time resolution of a few nanoseconds, as well as spatial resolution compatible with the pixel pitch.

Ball, R; Ben-Moshe, M; Benhammou, Y; Bensimon, R; Chapman, J W; Etzion, E; Ferretti, C; Friedman, P S; Levin, D S; Silver, Y; Varner, R L; Weaverdyck, C; Wetzel, R; Zhou, B; Anderson, T; McKinny, K; Bentefour, E H

2014-01-01

28

Electron gas grid semiconductor radiation detectors  

DOEpatents

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

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

2002-01-01

29

The pyroelectric detector of infrared radiation  

Microsoft Academic Search

The pyroelectric detector is a thermal sensor of infra-red radiation requiring no bias. While in principle a pure capacitor (hence theoretically noiseless), the detector has a varying noise contribution as a function of frequency due to a load resistor, series loss resistance, and amplifier. The actual sensor is a pyroelectric crystal exhibiting spontaneous polarization. The spontaneous polarization and dielectric constant

H. P. Beerman

1969-01-01

30

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

31

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

32

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

33

Glass fibers as radiation detectors  

NASA Astrophysics Data System (ADS)

The applicability of fiber-optic systems as dosimeters for ionizing radiation is discussed. The radiation sensitivities of different types of fibers show that lead-glass fibers should be used, if a small-sized dosimeter based on attenuation is required. On the other hand, Ge-doped fibers may be applied if a great length of fiber is needed. A distributed radiation sensor based on the OTDR (optical time-domain reflectometry) method is proposed for the radiation surveillance of nuclear facilities. For applications in radiotherapy, a small-sized lead-glass .dosimeter was developed.

Hille, R.; Bueker, H.; Haesing, F. W.

1990-12-01

34

Method of fabricating a self-powered radiation detector  

Microsoft Academic Search

A method is disclosed of fabricating a self-powered nuclear radiation detector assembly, comprising detector portion of accurately predetermined dimensions and a cable portion connected to the detector portion to carry the signal current which is generated in a radiation flux field to remote monitor means. The detector portion consists of a radiation responsive elongated central emitter electrode which is insulated

K. C. Playfoot; R. F. Bauer; Y. Sekella

1983-01-01

35

Low-Power Multi-Aspect Space Radiation Detector System  

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 all of these detector technologies will result in an improved detector system in comparison to existing state-of-the-art (SOA) instruments for the detection and monitoring of the deep space radiation field.

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

2012-01-01

36

Imaging radiation detector with gain  

DOEpatents

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

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

1982-07-21

37

Imaging radiation detector with gain  

DOEpatents

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

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

1984-01-01

38

Radiation damage in barium fluoride detector materials  

SciTech Connect

To develop radiation hard detectors, particularly for high energy physics studies, radiation damage is being studied in BaF/sub 2/, both undoped and doped with La, Ce, Nd, Eu, Gd and Tm. Some dopants reduce radiation damage. In La doped BaF/sub 2/ they reduce the unwanted long lifetime luminescence which interferes with the short-lived fluorescence used to detect particles. Radiation induced coloring is being studied with facilities for making optical measurements before, during and after irradiation with /sup 60/C0 gamma rays. Doses of 10/sup 6/ rad, or less, create only ionization induced charge transfer effects since lattice atom displacement damage is negligible at these doses. All crystals studied exhibit color center formation, between approximately 200 and 800 nm, during irradiation and color center decay after irradiation. Thus only measurements made during irradiation show the total absorption present in a radiation field. Both undoped and La doped BaF/sub 2/ develop damage at minimum detectable levels in the UV---which is important for particle detectors. For particle detector applications these studies must be extended to high dose irradiations with particles energetic enough to cause lattice atom displacement damage. In principle, the reduction in damage provided by dopants could apply to other applications requiring radiation damage resistant materials.

Levey, P.W.; Kierstead, J.A.; Woody, C.L.

1988-01-01

39

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

40

Improvement in the pyroelectric infrared radiation detector  

Microsoft Academic Search

Pyroelectric infrared radiation detectors of triglycline sulfate (TGS), triglycine fluoberyllate (TGFB), lithium sulfate, strontium barium niobate (SBN), and polycrystalline TGS are compared for responsivity, noise, and detectivity as a function of temperature. TGS, which currently exhibits the highest responsivity and detectivity at ambient temperature from 0.01 Hz to at least 10 KHz, is still one order of magnitude away in

Henry P. Beerman

1971-01-01

41

Radiation detectors: needs and prospects  

SciTech Connect

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

Armantrout, G.A.

1981-01-01

42

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

43

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

44

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

45

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

46

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

47

Development of a plasma panel radiation detector  

SciTech Connect

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

Ball, Robert [University of Michigan; Beene, James R [ORNL; Ben Moshe, M. [Tel Aviv University; Benhammou, Yan [Tel Aviv University; Bensimon, B [Tel Aviv University; Chapman, J. Wehrley [University of Michigan; Etzion, E [Tel Aviv University; Ferretti, Claudio [University of Michigan; Friedman, Dr. Peter S. [Integrated Sensors, LLC; Levin, Daniel S. [University of Michigan; Silver, Yiftah [Tel Aviv University; Weaverdyck, Curtis [University of Michigan; Wetzel, R. [University of Michigan; Zhou, Bing [University of Michigan; Anderson, T [GE Measurement and Control Solutions; McKinny, K [GE Measurement and Control Solutions; Bentefour, E [Ion Beam Applications

2014-01-01

48

Development of a plasma panel radiation detector  

NASA Astrophysics Data System (ADS)

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

Ball, R.; Beene, J. R.; Ben-Moshe, M.; Benhammou, Y.; Bensimon, B.; Chapman, J. W.; Etzion, E.; Ferretti, C.; Friedman, P. S.; Levin, D. S.; Silver, Y.; Varner, R. L.; Weaverdyck, C.; Wetzel, R.; Zhou, B.; Anderson, T.; McKinny, K.; Bentefour, E. H.

2014-11-01

49

Electromagnetic Radiation Hardness of Diamond Detectors  

E-print Network

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

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

2001-08-22

50

Electromagnetic Radiation Hardness of Diamond Detectors  

E-print Network

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

Behnke, T; Ghodbane, N; Imhof, A; Martínez, C; Zeuner, W

2002-01-01

51

Development of a plasma panel radiation detector  

E-print Network

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

R. Ball; J. R. Beene; M. Ben-Moshe; Y. Benhammou; R. Bensimon; J. W. Chapman; E. Etzion; C. Ferretti; P. S. Friedman; D. S. Levin; Y. Silver; R. L. Varner; C. Weaverdyck; R. Wetzel; B. Zhou; T. Anderson; K. McKinny; E. H. Bentefour

2014-03-13

52

Summary of the SWS Detector Radiation Effects  

NASA Astrophysics Data System (ADS)

We present a study of the space radiation effects on the ISO SWS detectors. Radiation effects were mainly recognised by the presence of glitches in the science data, although in some cases they were also associated with changes in detector responsivity, dark current levels and noise. The glitch rates observed in the science observation window were from 2 to 4 times higher than the value predicted by the CREME96 model for the cosmic ray flux in the period considered. A comparison of the glitch derived energy deposited distributions with the results of ray-tracing simulations (which model primary cosmic ray-induced glitches) showed a good agreement at high energies, but the peak of the observed distributions at the lower deposited energies was not reproduced. Furthermore we found a good correlation between the electron fluxes detected by the GOES-9 spacecraft and the glitch rates in the first measurements after perigee passage. These facts lead us to the conclusion that the contribution to the glitch rates from ?-rays and secondary particles produced by cosmic rays and electrons in the detectors and the shield were as important, at least, as the contribution from primary cosmic rays. The effects of the only intense solar proton event during the ISO mission, on 6 November 1997, on dark currents, dark current noise, responsivity and glitch rates were such that all observations in the revolution were declared failed. The space radiation environment affected the long term behaviour of band 3 Si:As detectors, causing their dark current levels, and in some cases their dark current noise, to increase during the mission. The other SWS detector bands were stable and did not show long-term trends.

Heras, A. M.; Wieprecht, E.; Nieminen, P.; Feuchtgruber, H.; Lahuis, F.; Leech, K.; Lorente, R.; Morris, P. W.; Salama, A.; Vandenbussche, B.

53

Modular radiation detector array and module  

SciTech Connect

A modular radiation detector array which allows improved spatial resolution and facilitates installation and replacement for repair. Each module includes two detachably assembled portions with one portion including a plurality of spaced plates for collimating radiation. The second portion includes a printed circuit board, a semiconductor diode array chip mounted on the printed circuit board, and a plurality of scintillator crystals mounted on the semiconductor chip with each crystal overlying a diode. Signals from the diodes are applied to signal processing means by a cable which is readily connected to and disconnected from the diode array.

Morehouse, C.C.; Shaw, R.H.

1982-07-06

54

GaN Radiation Detectors for Particle Physics and  

E-print Network

and neutrons led to a dramatic reduction in the CCE of the GaN detectors. For II #12;example, the CCE of oneGaN Radiation Detectors for Particle Physics and Synchrotron Applications James Paul Grant and monitoring applications. Gallium nitride (GaN) was investigated as a radiation hard particle detector

Glasgow, University of

55

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

56

Radiation hardness of Si strip detectors with integrated coupling capacitors  

Microsoft Academic Search

Si strip detectors with integrated coupling capacitors between diode and metallization and with separate bias resistors for each strip have been exposed to ionising radiation. Results from measurements of detector response before and after irradiation are presented.

H. Dijkstra; R. Horisberger; L. Hubbeling; G. Maehlum; A. Peisert; P. Weilhammer; T. Tuuva; L. Evensen

1989-01-01

57

A new transition radiation detector for cosmic ray nuclei  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

58

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

59

Physics with the ALICE Transition Radiation Detector  

E-print Network

The ALICE Transition Radiation Detector (TRD) significantly enlarges the scope of physics observables studied in ALICE, because it allows due to its electron identification capability to measure open heavy-flavour production and quarkonium states, which are essential probes to characterize the Quark-Gluon-Plasma created in nucleus-nucleus collisions at LHC. In addition the TRD enables to enhance rare probes due to its trigger contributions. We report on the first results of the electron identification capability of the ALICE Transition Radiation Detector (TRD) in pp collisions at $\\sqrt{s}$ = 7 TeV using a one-dimensional likelihood method on integrated charge measured in each TRD chamber. The analysis of heavy flavour production in pp collisions at $\\sqrt{s}$ = 7 TeV with this particle identification method, which extends the $p_{t}$ range of the existing measurement from $p_{t}$ = 4 GeV/c to 10 GeV/c and reduces the systematic uncertainty due to particle identification, is presented. The performance of the application of the TRD electron identification in the context of J/\\psi measurements in Pb-Pb collisions is also shown.

Yvonne Pachmayer for the ALICE Collaboration

2011-12-09

60

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

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)

2012-01-01

62

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

63

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

64

Radiation detectors for IR radiometers in unmanned interplanetary space stations  

NASA Astrophysics Data System (ADS)

The characteristics of thin-film bolometers and pyroelectric radiation detectors, used in IR equipment, are described. A transformerless low-noise circuit has been developed to match the low-resistance nickel bolometer to the measuring circuit. The construction of pyroelectric radiation detectors, based on triglycine sulfate, doped with L-alpha-alanine, and lithium niobate, is described.

Kremenchugskii, L. S.; Ksanfomaliti, L. V.; Samoilov, V. B.; Skliarenko, S. K.

1980-02-01

65

Effects of Gamma Irradiation on Silicon Carbide Semiconductor Radiation Detectors  

Microsoft Academic Search

Silicon carbide (SiC) semiconductor radiation detectors are being developed for alpha-particle, X- and gamma-ray, and fast-neutron energy spectrometry. SiC detectors have been operated at temperatures up to 306degC and have also been found to be highly resistant to the radiation effects of fast-neutron and charged-particle bombardments. In the present work, the alpha-particle response of a SiC detector based on a

Frank H. Ruddy; John G. Siedel

2006-01-01

66

Wire chamber radiation detector with discharge control  

DOEpatents

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

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

1984-01-01

67

Radiation damage studies for the DØ silicon detector  

NASA Astrophysics Data System (ADS)

We report on irradiation studies performed on spare production silicon detector modules for the current D Ø silicon detector. The lifetime expectations due to radiation damage effects of the existing silicon detector are reviewed. A new upgrade project was started with the goal of a complete replacement of the existing silicon detector. In that context, several investigations on the radiation hardness of new prototype silicon microstrip detectors were carried out. The irradiation on different detector types was performed with 10 MeV protons up to fluences of 10 14 p/ cm2 at the J.R. Mcdonald Laboratory at Kansas State University. The flux calibration was carefully checked using different normalisation techniques. As a result, we observe roughly 40-50% less radiation damage in silicon for 10 MeV p exposure than it is expected by the predicted NIEL scaling.

Lehner, Frank; DØ Collaboration

2004-09-01

68

Radiation damage studies for the D0 silicon detector  

SciTech Connect

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

Lehner, F.; /Zurich U.; ,

2004-01-01

69

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

70

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

71

A Xylophone Detector of Gravitational Radiation  

NASA Technical Reports Server (NTRS)

We discuss spacecraft Doppler tracking searches for gravitational waves in which Doppler data recorded on the ground are linearly combined with Doppler measurements made on board a spacecraft. By using the four-link radio system first proposed by Vessot and Levine, we describe a new method for removing from the combined data the frequency fluctuations due to the Earth troposphere, ionosphere, and mechanical vibrations of the antenna on the ground. This technique provides also a way for reducing by several orders of magnitude, at selected Fourier components, the frequency fluctuations due to other noise sources, such as the clock on board the spacecraft or the antenna and buffeting of the probe by nongravitational forces. In this respect spacecraft Doppler tracking can be regarded as a xylophone detector of gravitational radiation. In the assumption of calibrating the frequency fluctuations induced by the interplanetary plasma, a strain sensitivity equal to 4.7 x 10(exp -18) at 10(exp -3) Hz is estimated. This experimental technique could be extended to other tests of the theory of relativity, and to radio science experiments that rely on high-precision Doppler measurements.

Tinto, Massimo

1997-01-01

72

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

73

Radiation damage measurements in room temperature semiconductor radiation detectors  

SciTech Connect

The literature of radiation damage measurements on cadmium zinc telluride (CZT), cadmium telluride (CT), and mercuric iodide (HgI{sub 2}) is reviewed and in the case of CZT supplemented by new alpha particle data. CZT strip detectors exposed to intermediate energy (1.3 MeV) proton fluences exhibit increased interstrip leakage after 10{sup 10} p/cm{sup 2} and significant bulk leakage after 10{sup 12} p/cm{sup 2}. CZT exposed to 200 MeV protons shows a two-fold loss in energy resolution after a fluence of 5 {times} 10{sup 9} p/cm{sup 2} in thick (3 mm) planar devices but little effect in 2 mm devices. No energy resolution effects were noted from moderated fission spectrum of neutrons after fluences up to 10{sup 10} n/cm{sup 2}, although activation was evident. Exposures of CZT to 5 MeV alpha particle at fluences up to 1.5 {times} 10{sup 10} {alpha}/cm{sup 2} produced a near linear decrease in peak position with fluence and increases in FWHM beginning at about 7.5 {times} 10{sup 9} {alpha}/cm{sup 2}. CT detectors show resolution losses after fluences of 3 {times} 10{sup 9} p/cm{sup 2} at 33 MeV for chlorine-doped detectors. Indium doped material may be more resistant. Neutron exposures (8 MeV) caused resolution losses after fluences of 2 {times} 10{sup 10} n/cm{sup 2}. Mercuric iodide has been studied with intermediate energy protons (10 to 33 MeV) at fluences up to 10{sup 12} p/cm{sup 2} and with 1.5 GeV protons at fluences up to 1.2 {times} 10{sup 8} p/cm{sup 2}. Neutron exposures at 8 MeV have been reported at fluences up to 10{sup 15} n/cm{sup 2}. No radiation damage was reported under these irradiation conditions.

Franks, L.A.; Olsen, R.W.; James, R.B. [Sandia National Labs., Livermore, CA (United States); Brunett, B.A. [Sandia National Labs., Livermore, CA (United States)]|[Carnegie Mellon Univ., Pittsburgh, PA (United States); Walsh, D.S.; Doyle, B.L. [Sandia National Labs., Albuquerque, NM (United States); Vizkelethy, G. [Sandia National Labs., Albuquerque, NM (United States)]|[Idaho State Univ., Pocatello, ID (United States); Trombka, J.I. [National Aeronautics and Space Administration, Greenbelt, MD (United States). Goddard Space Flight Center

1998-12-01

74

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

75

Thermal treatment of CdTe surfaces for radiation detectors  

Microsoft Academic Search

In order to decrease the leakage current of In\\/CdTe\\/Au radiation detectors, thermal treatment of the CdTe wafers was introduced into the detector fabrication process. Detectors were fabricated from Cl-doped THM-grown high-resistivity wafers. The thermal treatment was carried out in a vacuum evaporator at 200–300°C before deposition of the In electrode. An Au electrode was formed by electroless plating. The thermal

T. Ozaki; Y. Iwase; H. Takamura; M. Ohmori

1996-01-01

76

Effects of ionizing radiation on cryogenic infrared detectors  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

77

Fast neutron detection with silicon carbide semiconductor radiation detectors  

Microsoft Academic Search

Silicon carbide (SiC) radiation detectors are being developed for high-temperature applications in harsh radiation environments. Among these applications are characterization of nuclear reactor fuel and detection of concealed fissionable materials, which both require the optimization of SiC fast neutron detectors for detection and quantification of fission neutrons. In order to enhance fast-neutron sensitivity, proton recoil techniques are being used. Fission

Robert W. Flammang; John G. Seidel; Frank H. Ruddy

2007-01-01

78

Studies of exotic nuclei with advanced radiation detectors  

NASA Astrophysics Data System (ADS)

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

Podolyák, Zsolt

2014-02-01

79

Polarization Phenomena in CdTe Nuclear Radiation Detectors  

Microsoft Academic Search

Nuclear radiation detectors made from high resistivity chlorine doped cadmium telluride grown by the travelling heater method were evaluated. Short term performance for ¿, ??, and ¿ radiations was good but the long term performance (>1 min) was degraded by a decrease in the full energy pulse height and ¿-ray efficiency with time after the bias voltage was applied. A

H. L. Malm; M. Martini

1974-01-01

80

Organic Semiconducting Crystals as Room Temperature Radiation Detectors  

NASA Astrophysics Data System (ADS)

We report on the use of organic semiconducting single crystals (OSSCs) as direct ionizing radiation detectors that directly convert the X-ray photons into an electrical signal, thanks to their stability, good transport properties and large interaction volume. X-ray detectors, based on low-cost solution-grown OSSCs are here shown to operate at room temperature, providing a stable linear response with increasing dose rate in atmosphere and in radiation-hard environment. The intrinsic conversion of ionizing radiation within the crystals allowed one to fabricate all-organic optically transparent devices, indicating OSSCs as very promising candidates for a novel generation of low-cost, room temperature radiation detectors.

Fraboni, Beatrice; Fraleoni-Morgera, Alessandro

2014-06-01

81

A Fiber Detector Radiation Hardness Test  

E-print Network

An intense 146 MeV/c pion beam was stopped inside a scintillating fiber detector made out of 12 planes with 16 pixels each, where every pixel consists out of 8 times 8 scintillating fibers of 500 mkm diameter dense packed. The detector was irradiated for 52 hours to more than 1 Mrad at its center. Before and directly after the irradiation the detector has been exposed to a particle beam to compare the corresponding light output. This study was continued during the following three months using cosmic rays. No damage was found taking into account the measurement errors of 5-10 %. In contrast a 9 cm deep lucite degrader became irreversibly non-transparent in the irradiation region.

J. Baehr; R. Nahnhauer; S. Nerreter; R. Shanidze

1999-07-13

82

Initial performance of the VENUS transition radiation detector  

Microsoft Academic Search

The VENUS-TRD is a cylindrical transition radiation detector, extending from 127 cm to 157.7 cm radially and 296 cm axially. It is designed to improve the e\\/pi separation capability of the VENUS detector by a factor of 10 in order to complement the lead glass calorimeter. It covers an angular region of cos theta < 0.68 and contains four layers

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

1992-01-01

83

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

84

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

85

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

86

Organic semiconductors as real-time radiation detectors  

NASA Astrophysics Data System (ADS)

In this study, the possibility of using ?-conjugated organic semiconducting polymers as real-time radiation detectors was explored. Polyaniline (PAni) was used to fabricate radiation sensors because of its relative long-term stability in air. Each fabricated sensor was then subjected to irradiation by ?- and ?-particles, and the real-time response was measured. The multichannel analyzer (MCA) data of the response signal for each irradiation was acquired and the detection efficiency, relative to the electrode bias voltage of the detector, was extracted.

Suzuki, T.; Miyata, H.; Katsumata, M.; Nakano, S.; Matsuda, K.; Tamura, M.

2014-11-01

87

(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

88

Transition Radiation Detector with Uniform pi\\/e Rejection Ability  

Microsoft Academic Search

We have developed a planar transition radiation detector to be used for electron tagging in the experiment of heavy quark decay. It consists of a radiator of multilayer polypropylene foils and a Xe gas multiwire proportional chamber for X-ray detection. The performance was tested in the mixed pi\\/e beam of several GeV\\/c range. With four modules of this type, the

Tadao Fujii; Hiroshi Fukushima; Mitsuhiro Kuwano; Norihiko Matsushita; Kouichi Nagai; Youko Umetani; Chiaki Yokoyama; Kazuyuki Fujiwara; Yoshiki Takahashi; Yasuhiro Homma

1989-01-01

89

Performance of the E715 transition radiation detector  

SciTech Connect

The transition radiation detector (TRD) consisted of 12 identical modules, each containing a radiator and a multiwire proportional counter (MWPC). A TRD is found to be an effective device for the identification of electrons in a large hadron background at Tevatron energies. The TRD proved to be a stable and reliable device with performance parameters in close agreement with theoretical predictions. The combination of a TRD with a lead glass calorimeter proved to be a very powerful method of electron identification. (LEW)

Denisov, A.; Grachev, V.; Kulikov, A.; Schegelsky, V.; Seliverstov, D.; Smirnov, N.; Terentyev, N.; Tkatch, I.; Vorobyov, A.; Hsueh, S.Y.

1984-01-01

90

Recent progress in the transition radiation detector techniques  

NASA Technical Reports Server (NTRS)

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

Yuan, L. C. L.

1973-01-01

91

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

92

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

93

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

94

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

95

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

Mihalczo, John T. (Oak Ridge, TN)

1994-01-01

96

Radiation physical chemistry effects on organic detectors  

Microsoft Academic Search

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 1.8Gy\\/s. The transmittance and the chemical degradation of those solutes were evaluated as a function of dose. The PPO transmittance at 360nm decayed

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

2003-01-01

97

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

98

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

99

Bismuth tri-iodide radiation detector development  

NASA Astrophysics Data System (ADS)

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

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

2009-08-01

100

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

Microsoft Academic Search

A laboratory test facility for solar radiation detectors has been built and is in operation at the Aerological Station of the Swiss Meterological Institute (SAP\\/SMI) This installation is conceived as a universal test bed for solar radiation exposed meterological instruments, and consists of a commercially available solar simulator, a laser alignment system, a translation mechanism with instrument mounts, and an

R. Philipona; A. Heimo; B. Hoegger

1993-01-01

101

Experiences with radiation portal detectors for international rail transport  

NASA Astrophysics Data System (ADS)

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

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

2006-08-01

102

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

103

Elements of a portable radiation detector calibration program.  

PubMed

The Department of Environmental Health & Safety at San Diego State University (SDSU) calibrates portable radiation detectors as a service to the university's research community. SDSU's calibration program was developed and implemented based on selected recommendations provided by the American National Standards Institute and the National Council on Radiation Protection and Measurements. This paper outlines the elements of the calibration program including, technical references and the rationale for program development. Covered under the provisions of this paper include those instruments used to evaluate the dose rates from radioactive materials and those instruments used to determine radioactive contamination or uptake. Those detectors specifically not addressed are liquid scintillation counters, semi-conductors, neutron dose rate instruments, and instruments intended for quantifying dose rates due to beta emission. PMID:10770159

Lanahan, M D

2000-05-01

104

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

105

Radiation characterization of a monolithic nuclear event detector  

SciTech Connect

A monolithic dose-rate nuclear event detector (NED) has been evaluated as a function of radiation pulse width. The dose-rate trip level of the NED was evaluated in ``near`` minimum and maximum sensitivity configurations for pulse widths from 20 to 250 ns and at dose rates from 10{sup 6} to 10{sup 9} rad(Si)/s. The trip level varied up to a factor of {approximately}16 with pulse width. At each pulse width the trip level can be varied intentionally by adding external resistors. Neutron n-regions caused an increase in the trip level, while electron irradiations, up to a total-dose of 50 krad(Si), had no measurable effect. This adjustable dose-rate-level detector should prove valuable to designers of radiation-hardened systems.

Hash, G.L.; Schwank, J.R.; Shaneyfelt, M.R. [Sandia National Labs., Albuquerque, NM (United States); Hughes, K.L.; Connors, M.P. [L and M Technologies, Inc., Albuquerque, NM (United States); Swonger, J.W.; van Vonno, N.W. [Harris Corp., Melbourne, FL (United States). Semiconductor Sector; Martin, R.L. [Naval Surface Warfare Center, Silver Spring, MD (United States)

1992-09-01

106

Radiation characterization of a monolithic nuclear event detector  

SciTech Connect

A monolithic dose-rate nuclear event detector (NED) has been evaluated as a function of radiation pulse width. The dose-rate trip level of the NED was evaluated in near'' minimum and maximum sensitivity configurations for pulse widths from 20 to 250 ns and at dose rates from 10{sup 6} to 10{sup 9} rad(Si)/s. The trip level varied up to a factor of {approximately}16 with pulse width. At each pulse width the trip level can be varied intentionally by adding external resistors. Neutron n-regions caused an increase in the trip level, while electron irradiations, up to a total-dose of 50 krad(Si), had no measurable effect. This adjustable dose-rate-level detector should prove valuable to designers of radiation-hardened systems.

Hash, G.L.; Schwank, J.R.; Shaneyfelt, M.R. (Sandia National Labs., Albuquerque, NM (United States)); Hughes, K.L.; Connors, M.P. (L and M Technologies, Inc., Albuquerque, NM (United States)); Swonger, J.W.; van Vonno, N.W. (Harris Corp., Melbourne, FL (United States). Semiconductor Sector); Martin, R.L. (Naval Surface Warfare Center, Silver Spring, MD (United States))

1992-01-01

107

VeriTainer radiation detector for intermodal shipping containers  

NASA Astrophysics Data System (ADS)

The VeriSpreader TM radiation detection system will monitor every container passing through a shipping terminal without impeding the flow of commerce by making the radiation measurements during normal container handling. This is accomplished by integrating neutron and spectroscopic ?-ray detectors into a container crane spreader bar, the part of the crane that directly engages the intermodal shipping containers while moving from ship to shore and vice versa. The use of a spectroscopic ?-detector reduces the rate of nuisance alarms due to naturally occurring radioactive material (NORM). The combination of ? and neutron detection reduces the effectiveness of shielding and countermeasures. The challenges in this spreader bar-based approach arise from the harsh environment, particularly the mechanical shock and the vibration of the moving spreader bar, since the measurement is taken while the container is moving. The electrical interfaces in the port environment, from the crane to a central monitoring office, present further challenges. It is the packaging, electronic interfaces, and data processing software that distinguish this system, which is based on conventional radiation sensors. The core of the system is Amptek's GAMMA-RAD, which integrates a ruggedized scintillator/PMT, digital pulse shaping electronics, electronics for the neutron detector, power supplies, and an Ethernet interface. The design of the VeriTainer system and results from both the laboratory and a proof-of-concept test at the Port of Oakland, California will be presented.

Redus, R. H.; Alioto, M.; Sperry, D.; Pantazis, T.

2007-08-01

108

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

DOEpatents

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

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

1994-09-13

109

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

110

SENTIRAD—An innovative personal radiation detector based on a scintillation detector and a silicon photomultiplier  

NASA Astrophysics Data System (ADS)

The alarming personal radiation detector (PRD) is a device intended for Homeland Security (HLS) applications. This portable device is designed to be worn or carried by security personnel to detect photon-emitting radioactive materials for the purpose of crime prevention. PRD is required to meet the scope of specifications defined by various HLS standards for radiation detection. It is mandatory that the device be sensitive and simultaneously small, pocket-sized, of robust mechanical design and carriable on the user's body. To serve these specialized purposes and requirements, we developed the SENTIRAD, a new radiation detector designed to meet the performance criteria established for counterterrorist applications. SENTIRAD is the first commercially available PRD based on a CsI(Tl) scintillation crystal that is optically coupled with a silicon photomultiplier (SiPM) serving as a light sensor. The rapidly developing technology of SiPM, a multipixel semiconductor photodiode that operates in Geiger mode, has been thoroughly investigated in previous studies. This paper presents the design considerations, constraints and radiological performance relating to the SENTIRAD radiation sensor.

Osovizky, A.; Ginzburg, D.; Manor, A.; Seif, R.; Ghelman, M.; Cohen-Zada, I.; Ellenbogen, M.; Bronfenmakher, V.; Pushkarsky, V.; Gonen, E.; Mazor, T.; Cohen, Y.

2011-10-01

111

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

112

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

113

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

114

PERDaix -Proton Electron Radiation Detector Aix-la-Chapelle  

NASA Astrophysics Data System (ADS)

For the purpose of understanding recent cosmic ray measurements in the energy region below 10 GeV it is important to obtain good knowledge of the charge-sign dependent modulation caused by interplanetary magnetic fields. Existing three-dimensional time-dependent models of the heliosphere can be constrained further using series of measurements of the low-energy cosmic ray fluxes over the course of a solar cycle. Following the measurements of the positron fraction from AESOP in 2006 and 2009, we present a new light-weighted spectrometer which is under construction in Aachen for measuring helium, proton, positron and electron fluxes. The detector is designed to measure in the energy range between 0.5 GeV and 5 GeV and identify helium, protons, electrons and positrons. The detector consists of a spectrometer made up of a permanent magnet and a scintillating fiber tracking detector, a transition radiation detector and a time of flight system with a total weight of approximately 30kg. We applied successfully for a flight on a stratosphere balloon in late 2010 as part of the German-Swedish Balloon-Borne Experiments for University Students (BEXUS) Program.

Schug, David; Schael, Stefan; Yearwood Roper, Gregorio; Bachlechner, Andreas; Beischer, Bastian; Deckenhoff, Mirco; Greim, Roman; Jenniches, Laura; Kucirek, Philipp; Lewke, Ronja; Mai, Carsten; Schug, David; Shchutska, Lesya; Tholen, Heiner; Ulrich, Jascha; Wienkenhoever, Jens; Zimmermann, Nikolas

115

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

116

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

SciTech Connect

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

Kueck, Stefan; Brandt, Friedhelm; Taddeo, Mario

2005-04-20

117

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

118

Technology demonstrator of radiation resistant photon counting detector  

NASA Astrophysics Data System (ADS)

The design, construction and performance test results of photon counting detector technology demonstrator based on silicon avalanche photodiodes is reported. This photon counting device have been designed and optimized for extremely high stability of their detection delay with applications in fundamental metrology and optical time transfer in space. The sensor is operated in an active quenching and gating mode. The single shot timing resolution is better than 25 ps rms over entire active area. Its detection delay is stable within 1 ps over several days of operation. All components in demonstrator have radiation resistant equivalents.

Prochazka, Ivan; Blazej, Josef; Kodet, Jan

2014-10-01

119

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

120

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

121

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

122

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

123

Micro-inhomogeneity effects and radiation damage in semi-insulating GaAs radiation detectors  

SciTech Connect

Thermally-stimulated current (TSC) measurements and a detailed analysis of current-voltage (I-V) characteristics have been made on semi-insulating GaAs (SI-GaAs) Schottky diode particle detectors, fabricated on substrates from several supplies, before and after irradiation with 24 GeV protons and 300 MeV pions. The analysis of I-V characteristics allows the determination of the barrier height and bulk resistance in detectors. Changes observed in I-V characteristics and TSC spectra after irradiation are described and a dislocation-net model of radiation-damaged devices is proposed.

Bates, R.; O`Shea, V.; Raine, C.; Smith, K.M. [Univ. of Glasgow (United Kingdom). Dept. of Physics and Astronomy] [Univ. of Glasgow (United Kingdom). Dept. of Physics and Astronomy; Didziulis, R.; Kazukauskas, V.; Rinkevicius, V.; Storasta, J. [Vilnius Univ. (Lithuania)] [Vilnius Univ. (Lithuania); Vaitkus, J. [Univ. of Glasgow (United Kingdom). Dept. of Physics and Astronomy] [Univ. of Glasgow (United Kingdom). Dept. of Physics and Astronomy; [Vilnius Univ. (Lithuania)

1998-06-01

124

Radiation Hard Hybrid Pixel Detectors, and a bbbar Cross Section Measurement at the CMS Experiment  

E-print Network

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...

Sibille, Jennifer Ann

2013-05-31

125

Charged Particle Measurements with the Radiation Assessment Detector on Board the Mars Science Laboratory  

NASA Astrophysics Data System (ADS)

The Radiation Assessment Detector (RAD) on board the MSL Curiosity rover is conducting the first-ever radiation measurements on the martian surface. Here, we present measurement results of charged particle fluxes and their temporal evolution.

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

2014-07-01

126

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

127

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

2007-07-09

128

Improved gas mixtures for gas-filled radiation detectors  

DOEpatents

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

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

1980-03-28

129

Gas mixtures for gas-filled radiation detectors  

DOEpatents

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

Christophorou, Loucas G. (Oak Ridge, TN); McCorkle, Dennis L. (Knoxville, TN); Maxey, David V. (Knoxville, TN); Carter, James G. (Knoxville, TN)

1982-01-05

130

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

131

Charge-trap correction and radiation damage in orthogonal-strip planar germanium detectors  

NASA Astrophysics Data System (ADS)

A charge-carrier trap correction technique was developed for orthogonal strip planar germanium gamma-ray detectors. The trap corrector significantly improves the gamma-ray energy resolution of detectors with charge-carrier trapping from crystal-growth defects and radiation damage. Two orthogonal-strip planar germanium detectors were radiation damaged with 2-MeV neutron fluences of ~8×109 n/cm2. The radiation-damaged detectors were studied in the 60-80 K temperature range.

Hull, E. L.; Jackson, E. G.; Lister, C. J.; Pehl, R. H.

2014-10-01

132

Grad-Level Radiation Damage of SIO2 Detectors  

SciTech Connect

Radiation effects and levels to detectors. SiO{sub 2} quartz fibers of the LHC ATLAS Zero-degree Calorimeter (ZDC) anticipated to experience integrated doses of a few Grad at their closest position were exposed to 200 MeV protons and neutrons at the Brookhaven National Laboratory (BNL) Linac. Specifically, 1 mm- and 2mm-diameter quartz (GE 124) rods were exposed to direct 200 MeV protons during the first phase of exposure leading to peak integrated dose of {approx}28 Grad. Exposure to a primarily neutron flux of 1mm-diameter SiO{sub 2} fibers was also achieved with a special neutron source arrangement. In a post-irradiation analysis the quartz fiber transmittance was evaluated as a function of the absorbed dose. Dramatic degradation of the transmittance property was observed with increased radiation damage. In addition, detailed evaluation of the fibers under the microscope revealed interesting micro-structural damage features and irradiation-induced defects.

Simos, N.; Atoian, G.; Ludewig, H; White, S; O'Conor, J; Mokhov, N.V.

2009-05-04

133

Particle Identification with the ALICE Transition Radiation Detector  

E-print Network

The Transition Radiation Detector (TRD) provides particle identification in the ALICE central barrel. In particular, it allows electron identification via the measurement of transition radiation for $\\rm p >$ 1 GeV/$c$, where pions can no longer be rejected sufficiently via specific energy loss in the ALICE Time Projection Chamber. The ALICE TRD is uniquely designed to record the time evolution of the signal, which allows even better electron/pion separation. In addition, the electron identification capability of the TRD can be used on-line to trigger at level 1. The particle identification and its performance in pp, p-Pb and Pb-Pb collisions employing various methods, such as truncated mean signal, one- and two-dimensional likelihood on integrated charge and neural network, will be presented. The measurement of J/$\\psi$ mesons in Pb-Pb collisions is given as a case study to show how well the TRD contributes to physics analyses due to its excellent pion suppression.

Yvonne Pachmayer for the ALICE Collaboration

2014-02-14

134

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

135

SEMICONDUCTOR NUCLEAR-RADIATION DETECTORS. SILICON JUNCTION DETECTORS OF GOOD RESOLUTION, LONG-TERM STABILITY AND FAST RISE TIME SUITABLE FOR NUCLEAR RESEARCH  

Microsoft Academic Search

Characteristics of the silicon junction detector and some examples of ; its applications to radiation detection are described. The range of effective ; detection was improved and its application to BETA and gamma measurements was ; expanded. Work was carried out toward the development of a series of radiation ; detectors including a lithium-ion drifted silicon (germanium) detector. (auth);

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

1963-01-01

136

Search for New Physics with AMS-02 Transition Radiation Detector  

NASA Astrophysics Data System (ADS)

Today the universe consists of 4.6% of ordinary matter, 23.3% of dark matter and 72.1% of dark energy. The dark matter is generally assumed be stable, non-relativistic and only weakly interacting. But we do not know what the dark matter is made of and how it is distributed within our Galaxy. In general, the cosmic antiparticles are expected as secondary products of interactions of the primary cosmic-rays (CRs) with the interstellar medium during propagation. While the measurements of CR positrons have become more precise, the results still do not match with the pure secondary origins. AMS-02 is a large acceptance precision particle spectrometer approved for installation on the International Space Station (ISS). A key feature of AMS-02 is precise particle identification for measurements of primary cosmic ray anti-particle spectra with negligible background up to a momentum of 500 GeV/c to allow indirect searches for dark matter. To efficiently separate positrons/electrons from protons/anti-protons, AMS-02 will be equipped with a Transition Radiation Detector (TRD) with 5248 straw tube proportional counters filled with a Xe/CO2 (80/20) mixture. The AMS-02 TRD was fully assembled and integrated into AMS-02 in 2007. In 2008 AMS-02 had recorded cosmic ray particles on ground to demonstrate full functionality of the device. For the AMS-02 TRD it will be shown that the detector response is as expected and the gas tightness will allow operation in space for 20 years with a gas supply of 25 kg.

Chung, Chanhoon

137

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

138

10th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors  

NASA Astrophysics Data System (ADS)

The primary goal of the Conference is to review the present status of the Semiconductor Detector apparatuses in the field of High Energy or Astroparticle Physics. In both cases the requests on the detector systems are very demanding: very large instrumented surface, radiation hardness and high reliability. During the conference a large part of the talks will be devoted to describe the pixel and microstrip silicon-based detectors operated in the LHC experiments (Alice, Atlas, CMS, LHCb). The operational experience and the detector performance with the p-p runs 2010-2011 will be discussed. A fraction of the talks will describe possible LHC luminosity upgrade (HL-LHC) and recent developments on detector radiation hardness. The astroparticle detectors activity will also be reviewed. Topics related to the development and applications of detector electronics will be presented too. Finally semiconductor applications in different fields, like medical Dosimetry and Photomultipliers will be rapidly touched.

139

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

140

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

141

Accelerated Detector - Quantum Field Correlations: From Vacuum Fluctuations to Radiation Flux  

E-print Network

In this paper we analyze the interaction of a uniformly accelerated detector with a quantum field in (3+1)D spacetime, aiming at the issue of how kinematics can render vacuum fluctuations the appearance of thermal radiance in the detector (Unruh effect) and how they engender flux of radiation for observers afar. Two basic questions are addressed in this study: a) How are vacuum fluctuations related to the emitted radiation? b) Is there emitted radiation with energy flux in the Unruh effect? We adopt a method which places the detector and the field on an equal footing and derive the two-point correlation functions of the detector and of the field separately with full account of their interplay. From the exact solutions, we are able to study the complete process from the initial transient to the final steady state, keeping track of all activities they engage in and the physical effects manifested. We derive a quantum radiation formula for a Minkowski observer. We find that there does exist a positive radiated power of quantum nature emitted by the detector, with a hint of certain features of the Unruh effect. We further verify that the total energy of the dressed detector and a part of the radiated energy from the detector is conserved. However, this part of the radiation ceases in steady state. So the hint of the Unruh effect in radiated power is actually not directly from the energy flux that the detector experiences in Unruh effect. Since all the relevant quantum and statistical information about the detector (atom) and the field can be obtained from the results presented here, they are expected to be useful, when appropriately generalized, for addressing issues of quantum information processing in atomic and optical systems, such as quantum decoherence, entanglement and teleportation.

Shih-Yuin Lin; B. L. Hu

2005-07-13

142

Accelerated detector-quantum field correlations: From vacuum fluctuations to radiation flux  

SciTech Connect

In this paper we analyze the interaction of a uniformly accelerated detector with a quantum field in (3+1)D spacetime, aiming at the issue of how kinematics can render vacuum fluctuations the appearance of thermal radiance in the detector (Unruh effect) and how they engender flux of radiation for observers afar. Two basic questions are addressed in this study: (a) How are vacuum fluctuations related to the emitted radiation? (b) Is there emitted radiation with energy flux in the Unruh effect? We adopt a method which places the detector and the field on an equal footing and derive the two-point correlation functions of the detector and of the field separately with full account of their interplay. From the exact solutions, we are able to study the complete process from the initial transient to the final steady state, keeping track of all activities they engage in and the physical effects manifested. We derive a quantum radiation formula for a Minkowski observer. We find that there does exist a positive radiated power of quantum nature emitted by the detector, with a hint of certain features of the Unruh effect. We further verify that the total energy of the dressed detector and a part of the radiated energy from the detector is conserved. However, this part of the radiation ceases in steady state. So the hint of the Unruh effect in radiated power is actually not directly from the energy flux that the detector experiences in Unruh effect. Since all the relevant quantum and statistical information about the detector (atom) and the field can be obtained from the results presented here, they are expected to be useful, when appropriately generalized, for addressing issues of quantum information processing in atomic and optical systems, such as quantum decoherence, entanglement, and teleportation.

Lin, S.-Y.; Hu, B.L. [Center for Quantum and Gravitational Physics, Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan (China) and Department of Physics, University of Maryland, College Park, Maryland 20742-4111 (United States)

2006-06-15

143

Ion Beam Induced Charge Collection (IBICC) Studies of Cadmium Zinc Telluride (CZT) Radiation Detectors  

SciTech Connect

Cadmium Zinc Telluride 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 and Time Resolved IBICC (TRIBICC) were used to image electronic properties of various CZT detectors. Two-dimensional areal maps of charge collection efficiency were deduced from the measurements. In order to determine radiation damage to the detectors, we measured the deterioration of the IBICC signal as the function of dose. A model to explain quantitatively the pattern observed in the charge collection efficiency maps of the damaged detectors has been developed and will be discussed in the paper.

Doyle, B.L.; Vizkelethy, G.; Walsh, D.S.

1999-07-22

144

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

145

Status of radiation damage measurements in room temperature semiconductor radiation detectors  

SciTech Connect

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

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

1998-04-01

146

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

147

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

148

Design, processing and operation of a large area pin diode radiation detector  

Microsoft Academic Search

Silicon pin diode is designed for operation as a radiation detector. The detector can operate in photovoltaic as well as photoconductive mode with AC or DC coupling. The structure is equipped with a special spiral junction termination structure to prevent surface leakage currents entering active device region and improve breakdown properties of the device. Optimized low temperature processing steps have

D. Krizaj; D. Resnik; D. Vrtancnik; U. Uljancic; S. Amon; V. Cindro

1998-01-01

149

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

SciTech Connect

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

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

2010-06-01

150

X-ray silicon detectors for measuring hard x-ray radiation damage effects  

Microsoft Academic Search

For high sensitivity hard x-ray detector applications there is a solid-state alternative using high purity silicon as starting material. The paper presents some original results concerning a radiation hardened technology to be used for obtaining x-ray silicon detectors and the behavior of the special designed devices in a specific radiation environment. Original processing sequences were experimentally tested and results concerning

Delia Wagner; Eugenia T. Halmagean; Dido Y. Loukas; K. Misiakos; Elisabeth Tsoi; A. Veron; M. Ohanisian

1997-01-01

151

Advances in gas avalanche radiation detectors for biomedical applications  

E-print Network

diagnostics, gaseous detectors are currently employed in digital X-ray radiography [6] and angiography [7]. In X-ray radiography, large-volume xenon-"lled detectors, with wires oriented towards a narrow fanned charged particles, X-ray photons and thermal neutrons with sub- millimeter accuracies, over detection

152

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

SciTech Connect

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

Philipona, R.; Heimo, A.; Hoegger, B. (Aerological Station of the Wiss Meterological Institute, Payerne (Switzerland))

1993-08-01

153

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

154

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

155

Gamma-ray detectors for intelligent, hand-held radiation monitors  

SciTech Connect

Small radiation detectors based on HgI/sub 2/, bismuth germanate (BGO), plastic, or NaI(Tl) detector materials were evaluated for use in small, lighweight radiation monitors. The two denser materials, HgI/sub 2/ and BGO, had poor resolution at low-energy and thus performed less well than NaI(Tl) in detecting low-energy gamma rays from bare, enriched uranium. The plastic scintillator, a Compton recoil detector, also performed less well at low gamma-ray energy. Two small NaI(Tl) detectors were suitable for detecting bare uranium and sheilded plutonium. One became part of a new lightweight hand-held monitor and the other found uses as a pole-mounted detector for monitoring hard-to-reach locations.

Fehlau, P.E.

1983-01-01

156

Recent Advances in the Development of Radiation Tolerant Silicon Detectors for the Super-Lhc  

NASA Astrophysics Data System (ADS)

For the luminosity upgrade of the LHC, the sLHC, the tracking systems of the experiments need to be replaced. A main concern is the extreme radiation hardness requirements of up to a 1 MeV neutron equivalent fluence of about 1016cm-2. In this paper recent results on radiation hardening technologies developed within the RD50 Collaboration are described. Silicon detectors have been designed and produced on n- and p-type wafers made by Float Zone, epitaxy and Czochralski technology. Their charge collection efficiency after proton, neutron and mixed irradiation has been studied. Novel detector concepts, as 3D detectors, have been designed, produced and studied as well. Radiation induced microscopic defects have been investigated and could be partly linked to the performance degradation of irradiated detectors.

Moll, Michael

2010-04-01

157

Extended Defects in CdZnTe Radiation Detectors  

Microsoft Academic Search

Large-volume CdZnTe (CZT) single crystals with electron lifetime exceeding 10 mus have recently become commercially available. This opened the opportunity for making room temperature CZT gamma-ray detectors with extended thicknesses and larger effective areas. However, the extended defects that are present even in the highest-quality material remain a major drawback which affects the availability and cost of large CZT detectors.

Aleksey E. Bolotnikov; Stephen O. Babalola; Giuseppe S. Camarda; Henry Chen; S. Awadalla; Yonggang Cui; Stephrn U. Egarievwe; Petro M. Fochuk; Rastgo Hawrami; Anwar Hossain; Jesse R. James; I. J. Nakonechnyj; J. MacKenzie; Ge Yang; Chao Xu; Ralph B. James

2009-01-01

158

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

159

Trap influence on the performance of gallium arsenide radiation detectors  

SciTech Connect

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

Castaldini, A.; Cavallini, A.; Polenta, L. [Univ. of Bologna (Italy); Canali, C.; Nava, F. [Univ. of Modena (Italy); Papa, C. del [Univ. of Udine (Italy). Dept. of Physics

1996-12-31

160

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

161

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

162

Over-response of synthetic microDiamond detectors in small radiation fields.  

PubMed

The recently commercialized PTW microDiamond detector (T60019) has been designed for use in small radiation fields. Here we report on the measurement of relative output ratios for small fields using five microDiamond detectors. All of the microDiamond detectors over-responded in fields smaller than 20?mm, by up to 9.3% for a 4?mm field. The over-response was independent of accelerator type and choice of collimation. The over-response was slightly larger than that observed in silicon diodes. Since all five microDiamond detectors showed the same over-response the corrections presented here should be transferable to other examples of the microDiamond detector, provided that the detector meets the manufacturing specifications and the beam characteristics are comparable. PMID:25211368

Ralston, Anna; Tyler, Madelaine; Liu, Paul; McKenzie, David; Suchowerska, Natalka

2014-10-01

163

Over-response of synthetic microDiamond detectors in small radiation fields  

NASA Astrophysics Data System (ADS)

The recently commercialized PTW microDiamond detector (T60019) has been designed for use in small radiation fields. Here we report on the measurement of relative output ratios for small fields using five microDiamond detectors. All of the microDiamond detectors over-responded in fields smaller than 20?mm, by up to 9.3% for a 4?mm field. The over-response was independent of accelerator type and choice of collimation. The over-response was slightly larger than that observed in silicon diodes. Since all five microDiamond detectors showed the same over-response the corrections presented here should be transferable to other examples of the microDiamond detector, provided that the detector meets the manufacturing specifications and the beam characteristics are comparable.

Ralston, Anna; Tyler, Madelaine; Liu, Paul; McKenzie, David; Suchowerska, Natalka

2014-10-01

164

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

Rafkin, Scot

165

Electromagnetic and nuclear radiation detector using micromechanical sensors  

DOEpatents

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

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

2000-01-01

166

Radiation Hard AlGaN Detectors and Imager  

SciTech Connect

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

None

2012-05-01

167

Radiation-hard semiconductor detectors for SuperLHC  

Microsoft Academic Search

An option of increasing the luminosity of the Large Hadron Collider (LHC) at CERN to 1035cm?2s?1 has been envisaged to extend the physics reach of the machine. An efficient tracking down to a few centimetres from the interaction point will be required to exploit the physics potential of the upgraded LHC. As a consequence, the semiconductor detectors close to the

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

2005-01-01

168

Radiation Tests for a Single-GEM Loaded Gaseous Detector  

E-print Network

We report on the systematic study of a single-gas-electron-multiplication (GEM) loaded gaseous detector developed for precision measurements of high-energy particle beams and dose-verification measurements. In the present study, a 256-channel prototype detector with an active area of 16$\\times$16 cm$^{2}$, operated in a continuous current-integration-mode signal-processing method, was manufactured and tested with x rays emitted from a 70-kV x-ray generator and 43-MeV protons provided by the MC50 proton cyclotron at the Korea Institute of Radiological and Medical Science (KIRAMS). The amplified detector response was measured for the x rays with an intensity of about 5$\\times$10$^{6}$ Hz cm$^{-2}$. The linearity of the detector response to the particle flux was examined and validated by using 43-MeV proton beams. The non-uniform development of the amplification for the gas electrons in space was corrected by applying proper calibration to the channel responses of the measured beam-profile data. We concluded fro...

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

2014-01-01

169

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

170

Purification and preparation of TlBr crystals for room temperature radiation detector applications  

Microsoft Academic Search

Thallium bromide (TlBr) is a semiconductor compound with a high atomic number and a wide bandgap, being a very promising material to be used as room temperature radiation detectors. In this work, commercial TlBr powder was used for growing crystals for detector applications. To reduce impurities, this material was purified by the zone refining technique. Trace impurities at ppb\\/ppm level

Icimone B. Oliveira; Fábio E. Costa; José F. D. Chubaci; Margarida M. Hamada

2004-01-01

171

Development of new silica aerogel for the RICH radiator of the Super Belle detector  

Microsoft Academic Search

Currently, we are working on the program of the Belle detector upgrade, and the Cherenkov ring imaging counter with silica aerogel radiator (aerogel-RICH) is the most promising candidate for the particle identification device (PID) at the endcap section of the BELLE detector, where a threshold-type aerogel Cherenkov counter is occupied at present, in order to further expand pi-K separation capabilities

Adachi; S. Fratina; T. Fukushima; A. Gorisek; T. Iijima; H. Kawai; H. Kishimoto; M. Konishi; S. Korpar; Y. Kozakai; P. Krizan; T. Matsumoto; S. Nishida; S. Ogawa; R. Pestotnik; S. Saitoh; T. Seki; T. Sumiyoshi; Y. Uchida; Y. Unno; S. Yamamoto; H. Yokogawa

2004-01-01

172

Radiation hard silicon detectors—developments by the RD48 (ROSE) collaboration  

Microsoft Academic Search

The RD48 (ROSE) collaboration has succeeded to develop radiation hard silicon detectors, capable to withstand the harsh hadron fluences in the tracking areas of LHC experiments. In order to reach this objective, a defect engineering technique was employed resulting in the development of Oxygen enriched FZ silicon (DOFZ), ensuring the necessary O-enrichment of about 2×1017 O\\/cm3 in the normal detector

G. Lindström; M. Ahmed; S. Albergo; P. Allport; D. Anderson; L. Andricek; M. M. Angarano; V. Augelli; N. Bacchetta; P. Bartalini; R. Bates; U. Biggeri; G. M. Bilei; D. Bisello; D. Boemi; E. Borchi; T. Botila; T. J. Brodbeck; M. Bruzzi; T. Budzynski; P. Burger; F. Campabadal; G. Casse; E. Catacchini; A. Chilingarov; P. Ciampolini; V. Cindro; M. J. Costa; D. Creanza; P. Clauws; C Da Via; G. Davies; W De Boer; R Dell’Orso; M De Palma; B. Dezillie; V. Eremin; O. Evrard; G. Fallica; G. Fanourakis; H. Feick; E. Fretwurst; L. Fonseca; J. Fuster; K. Gabathuler; M. Glaser; P. Grabiec; E. Grigoriev; G. Hall; M. Hanlon; F. Hauler; S. Heising; A. Holmes-Siedle; R. Horisberger; G. Hughes; M. Huhtinen; I. Ilyashenko; A. Ivanov; B. K Jones; L. Jungermann; A. Kaminsky; Z. Kohout; G. Kramberger; M. Kuhnke; S. Kwan; F. Lemeilleur; C. Leroy; M. Letheren; Z. Li; T. Ligonzo; V. Linhart; P. Litovchenko; D. Loukas; M. Lozano; Z. Luczynski; G. Lutz; B. MacEvoy; S. Manolopoulos; A. Markou; C. Martinez; A. Messineo; M. Mikuz; M. Moll; E. Nossarzewska; G. Ottaviani; V. Oshea; G. Parrini; D. Passeri; D. Petre; A. Pickford; I. Pintilie; L. Pintilie; S. Pospisil; R. Potenza; C. Raine; J. M Rafi; P. N Ratoff; R. H Richter; P. Riedler; S. Roe; P. Roy; A. Ruzin; A. I. Ryazanov; A. Santocchia; L. Schiavulli; P. Sicho; I. Siotis; T. Sloan; W. Slysz; K. Smith; M. Solanky; B. Sopko; K. Stolze; B Sundby Avset; B. Svensson; C. Tivarus; G. Tonelli; A. Tricomi; S. Tzamarias; G. Valvo; A. Vasilescu; A. Vayaki; E. Verbitskaya; P. Verdini; V. Vrba; S. Watts; E. R Weber; M. Wegrzecki; I. Wegrzecka; P. Weilhammer; R. Wheadon; C. Wilburn; I. Wilhelm; R. Wunstorf; J. Wüstenfeld; J. Wyss; K. Zankel; P. Zabierowski; D Žontar

2001-01-01

173

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

Microsoft Academic Search

The proposed luminosity upgrade of the Large Hadron Collider (S-LHC) at CERN will demand the innermost layers of the vertex detectors to sustain fluences of about 1016 hadrons\\/cm2. Due to the high multiplicity of tracks, the required spatial resolution and the extremely harsh radiation field new detector concepts and semiconductor materials have to be explored for a possible solution of

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

2005-01-01

174

Review on the characteristics of radiation detectors for dosimetry and imaging  

NASA Astrophysics Data System (ADS)

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

Seco, Joao; Clasie, Ben; Partridge, Mike

2014-10-01

175

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

PubMed

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

Seco, Joao; Clasie, Ben; Partridge, Mike

2014-10-21

176

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

SciTech Connect

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

O`Brien, E.; Lissauer, D.; McCorkle, S.; Polychronakos, V.; Takai, H. [Brookhaven National Lab., Upton, NY (United States); Chi, C.Y.; Nagamiya, S.; Sippach, W.; Toy, M.; Wang, D.; Wang, Y.F.; Wiggins, C.; Willis, W. [Columbia Univ., New York, NY (United States); Cherniatin, V.; Dolgoshein, B. [Moscow Institute of Physics and Engineering, (Russian Federation); Bennett, M.; Chikanian, A.; Kumar, S.; Mitchell, J.T.; Pope, K. [Yale Univ., New Haven, CT (United States)

1991-12-31

177

The influence of inhomogeneities in materials properties in silicon radiation detectors  

NASA Astrophysics Data System (ADS)

When fast ions are incident on a silicon nuclear radiation detector, the current pulses observed with high bandwidth electronics can show marked features which depend on materials inhomogeneities in the silicon from which the detector is made. This paper describes how an attempt to develop an atomic number pulse shape discrimination technique for fission fragments led instead to an investigation of the materials effects in the surface barrier detectors which were being used. Results obtained with alpha particles and accelerator-produced heavy ions scanned across a detector face are correlated with each other and with laser photoresponse studies which were also made. The effects in such measurements which spatial resistivity and thickness changes can produce are analysed in particular detail. For the two main detectors studied the evidence all indicates that in their cases resistivity inhomogeneities were responsible for the results observed.

Henari, F. Z.; Finch, E. C.; Delaney, C. F. G.

1990-03-01

178

Radiation damage due to NIEL in GaAs particle detectors  

NASA Astrophysics Data System (ADS)

The Non-Ionizing Energy Loss (NIEL) for fast neutrons, protons and pions in GaAs has been estimated from published calculations. The values are then used to search for a correlation between the observed reduction of charge collection efficiency (CCE) in GaAs particle detectors with the radiation dose from NIEL. A correlation is demonstrated to be present for detectors made from a wide range of material. The implications for the performance of GaAs detectors at the Large Hadron Collider (LHC) are discussed.

Chilingarov, A.; Meyer, J. S.; Sloan, T.

1997-08-01

179

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

180

Dosimetry of Ionizing Radiation: In Search of an Ideal Detector  

Microsoft Academic Search

\\u000a Proper dose measurement skills are of the utmost importance for all applications of ionizing radiation in medicine. For years,\\u000a since the discovery of ionizing radiation, the delivered dose to exposed people has been evaluated by means of subjective\\u000a methods. In radiotherapy, the unit “erythema dose” was widely used. The erythema dose was connected to the reaction of the\\u000a skin to

Pawel Kukolowicz

181

[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

182

Feasibility study of a plasma display-like radiation detector for X-ray imaging.  

PubMed

In this study we have investigated a 2-dimensional gas type detector based on plasma display technology as a candidate for the flat-panel radiation detector. By using the Garfield code, the dependence of X-ray absorption and multiplication on gas composition, cell gap and electric field were examined. Considering the simulation results, three prototype detectors were designed and fabricated. The performance of these detectors was evaluated by measuring the collected charge density, dark current density and sensitivity. The collected charge had the highest value at a condition when Xe 100% and 2.8 mm gap was 108.8 nC/cm² at 1000 V. The dark current of the same detector was varied from 0.0095 to 0.10 nA/cm² and about a fourth of the dark current density of a-Se based detector was at the bias range of 100-1000 V. The sensitivity of Xe 100% and 2.8 mm detector was 0.20 nC/mR·cm² at 0.36 V/um. It is about a tenth lower than that of a-Se based detector at 10 V/um. PMID:22948349

Eom, Sangheum; Shin, Hyoungsup; Kang, Jungwon; Lee, Hakjae; Lee, Kisung

2012-01-01

183

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

184

A pn-SiC diode as a radiation detector  

Microsoft Academic Search

We evaluated pn-SiC (silicon carbide) particle detectors exposed to 5.486 MeV alpha particles from a sealed radioactive source of 241Am and 3.26 eV (380 nm) pulsed Ultra-Violet (UV) light at 100 Hz from a Light Emitting Diode (LED). The pn junction SiC diode was made by the implantation of phosphorus (P) ions (140, 60, 90 keV) into p-type 6H-SiC epitaxial

A. Kinoshita; M. Iwami; I. Nakano; R. Tanaka; T. Kamiya; A. Ohi; T. Ohshima; Y. Fukushima

2003-01-01

185

A Cherenkov Radiation Detector with High Density Aerogels  

E-print Network

We have designed a threshold Cherenkov detector at the Rutherford-Appleton Laboratory to identify muons with momenta between 230 and 350 MeV/c. We investigated the properties of three aerogels for the design. The nominal indexes of refraction were n = 1.03, 1.07, 1.12, respectively. Two of the samples are of high density aerogel not commonly used for Cherenkov light detection. We present results of an examination of some optical properties of the aerogel samples and present basic test beam results.

Cremaldi, Lucien; Sonnek, Peter; Summers, Donald J; Reidy, Jim

2009-01-01

186

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

187

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

NASA Astrophysics Data System (ADS)

The product of the radiation dose and radiation quality indicates the biological consequences of radiation exposure. Therefore, quantifying both radiation dose and radiation quality is important to biological experiments as well as radiation protection. A small, specialized amplifier based on commercial ICs was developed to measure the radiation dose and quality in real-time using a microdosimetric detector, operated in the current mode, and the variance method. The random nature of radiation induces variance in the dose (in a small volume such as that of cell or DNA) for a specific radiation field that is proportional to the radiation quality. The charges from the microdosimetric detector, operated in the current mode, were repeatedly collected for a fixed period of time for 20 cycles of 100 integrations, and processed by the specialized amplifier to produce signals of pulse height between 0 and 10 volts. These signals with various amplitudes, which are proportional to the channel number, were then recorded by the MCA and stored in a computer. FORTRAN programs written in this study then calculated the average dose and the average dose variance from the stored data. Benchmarks of different brand's ICs were conducted to select a component with the best performance versus cost. The specialized amplifier showed the following characteristics: low input capacitance, low output impedance, adjustable integration time for controlling the amount of charge collected from the detector, linearity of system response to input currents, adjustable gain control, and low background noise. Standardized procedures of constructing a functional device (the specialized amplifier) were established, including arrangements of circuit diagram, processing of a printed circuit board, and construction of an aluminum-shielding box that served as a united ground point. In addition, procedures for determining the inner dimensions of the detector using radiography are also presented along with procedures for calibration and measurement. Measurements of the radiation dose and quality of x-ray, gamma and mixed neutron-gamma radiation fields with various geometries were taken. The dose rates ranged from 4 to 60 Gy/hr. Results showed the specialized amplifier is capable of distinguishing differences of radiation quality in various high dose rate radiation fields.

Hsu, Wen-Hsing

188

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

189

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

190

Process considerations in reducing leakage current of PIN radiation detectors  

Microsoft Academic Search

PIN diode structures for radiation detection were designed and fabricated on high resistivity silicon wafers by means of planar process. Technological process development of the device and resulting electrical characteristics are presented. Extrinsic gettering with polysilicon and n+ phosphorus doped back side layer was employed. Surface passivation with dry or wet thermal oxide in combination with silicon nitride was performed

D. Resnik; D. Krizaj; D. Vrtacnik; S. Amon

2000-01-01

191

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

SciTech Connect

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

Bertschinger, G.; Oosterbeek, J. W. [Institut fuer Energieforschung-Plasmaphysik, Forschungszentrum Juelich, Association EURATOM-FZJ, Trilateral Euregio Cluster, 52425 Juelich (Germany); Endres, C. P.; Lewen, F. [I. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Koeln (Germany)

2008-10-15

192

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

193

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

194

Operational Characteristics of SiC Diodes as Ionizing Radiation Detectors  

SciTech Connect

In order to explore the possibility of using SiC detectors in nuclear physics applications in extreme environments, the operational characteristics of 4H-SiC Schottky diodes with different dopant concentrations have been studied with {sup 12}C and {sup 16}O ions at various incident energies. The detector response has been investigated in term of linearity, energy resolution, signal rise-time and Charge Collection Efficiency as a function of the applied reverse bias and of the dopant concentration. Moreover, since one of the most promising properties of SiC detectors is their radiation hardness, the radiation damage, produced by irradiating SiC diodes with {sup 16}O ions at 35.2 MeV, has been evaluated by measuring the degradation of both the signal pulse-height and the energy resolution as a function of the {sup 16}O fluence.

De Napoli, M.; Raciti, G.; Rapisarda, E.; Sfienti, C. [Dipartimento di Fisica e Astronomia, Universita degli Studi di Catania, Via S. Sofia 64, 95123 Catania-Italy (Italy); INFN-Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Giacoppo, F. [INFN-Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica, Universita degli Studi di Messina, Via Salita Sperone 31, I-98166 Messina (Italy)

2009-12-02

195

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

196

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

197

A new thermal radiation detector using optical heterodyne detection of absorbed energy  

NASA Technical Reports Server (NTRS)

The operating principles of a new kind of room-temperature thermal radiation detector are described. In this device modulated light heats a gas, either directly or by conduction from a thin absorbing membrane, and the resultant change in density of the gas is detected by optical heterodyning. The performance of a membrane device of this kind agrees well with the predictions of theory.

Davis, C. C.; Petuchowski, S. J.

1983-01-01

198

Investigation of efficient termination structure for improved breakdown properties of semiconductor radiation detectors  

Microsoft Academic Search

Efficiency of a new junction termination structure for improvement of breakdown properties of semiconductor radiation detectors is investigated. The structure consists of a diffused resistor winding around the active junction in a spiral fashion. The current flow through the spiral enables controlled potential distribution along the spiral turns and thus controlled depletion spreading from the main junction, efficiently preventing premature

D. Krizaj; D. Resnik; D. Vrtacnik; S. Amon; V. Cindro

1998-01-01

199

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

SciTech Connect

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

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

1999-01-01

200

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

201

Exploring RF Transmissions From Discharge-Based Micromachined Radiation Detectors  

Microsoft Academic Search

This paper describes micromachined gas-based radiation sensors that are capable of radio frequency wireless signaling, and their possible utility in networks. The devices include a gas-filled region with a high electric field, in which incident beta-particles initiate avalanche breakdown. Under the proper circumstances, the resulting current pulses can inherently produce wireless transmissions. Two types of lithographically-manufactured devices are presented: (1)

Christine K. Eun; Y. B. Gianchandani

2008-01-01

202

Field-deployable gamma-radiation detectors for DHS use  

Microsoft Academic Search

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

Sanjoy Mukhopadhyay

2007-01-01

203

A new type of sensitive semiconductor detectors of terahertz radiation  

NASA Astrophysics Data System (ADS)

Doping of the lead telluride and related alloys with the group III impurities results in appearance of the unique physical features of a material, such as persistent photoresponse, enhanced responsive quantum efficiency (up to 100 photoelectrons/incident photon), radiation hardness and many others. We present the physical principles of operation of the photodetecting devices based on the group III-doped IV-VI including the possibilities of a fast quenching of the persistent photoresponse, construction of the focal-plane array, new readout technique, and others. The advantages of infrared photodetecting systems based on the group III-doped IV-VI in comparison with the modern photodetectors are summarized. The spectra of the persistent photoresponse have not been measured so far because of the difficulties with screening the background radiation. We report on the observation of strong persistent photoconductivity in Pb0.75Sn0.25Te(In) under the action of monochromatic submillimeter radiation at wavelengths of 176 and 241 microns. The sample temperature was 4.2 K, the background radiation was completely screened out. The sample was initially in the semiinsulating state providing dark resistance of more than 100 GOhm. The responsivity of the photodetector is by several orders of magnitude higher than in the state of the art Ge(Ga). The red cut-off wavelength exceeds the upper limit of 220 microns observed so far for the quantum photodetectors in the uniaxially stressed Ge(Ga). It is possible that the photoconductivity spectrum of Pb1-xSnxTe(In)covers all the submillimeter wavelength range.

Dolzhenko, D. E.; Nicorici, A. V.; Ryabova, L. I.; Khokhlov, D. R.

2012-06-01

204

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

205

A single-photon counting “edge-on” silicon detector for synchrotron radiation mammography  

NASA Astrophysics Data System (ADS)

The Phase Imaging for Clinical Application with Silicon detector and Synchrotron radiatiOn (PICASSO) project is developing an "edge-on" silicon microstrip detector for mammography with synchrotron radiation. The sensor is equipped with a fast single-photon counting electronics based on the Mythen-II application-specific integrated circuit. A first prototype has been assembled and tested at the SYnchrotron Radiation for MEdical Physics (SYRMEP) beamline at Elettra in Trieste, Italy. The first results are presented in this study including evidence of high-rate single-photon counting with negligible losses up to 1.2×10 6 incident photons per pixel per second; spatial resolution consistent with the pixel aperture (0.3 mm×0.05 mm); high-quality imaging of test-objects, obtained with a dose comparable to the one delivered in modern full-field digital mammographic systems.

Rigon, L.; Arfelli, F.; Astolfo, A.; Bergamaschi, A.; Dreossi, D.; Longo, R.; Menk, R.-H.; Schmitt, B.; Vallazza, E.; Castelli, E.

2009-09-01

206

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

NASA Astrophysics Data System (ADS)

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 Gd2SiO5 (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.

Yamamoto, Seiichi; Hatazawa, Jun

2011-11-01

207

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

SciTech Connect

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

Yamamoto, Seiichi [Kobe City College of Technology, 8-3, Gakuen-Higashi-machi, Nishi-ku, Kobe, 651-2194 (Japan); Hatazawa, Jun [Osaka University of Graduate School of Medicine, 2-2, Yamadaoka, Suita-shi, Osaka, 565-0871 (Japan)

2011-11-15

208

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

209

The ISO-SWS detectors: Performance trends and space radiation effects  

NASA Astrophysics Data System (ADS)

We present a trend analysis of the ISO-SWS detector performance and a study of the space radiation effects on the SWS detectors. In particular, dark currents, dark current noise and detector responses have been checked as a function of time through the mission and as a function of time in a revolution. The results show that these parameters were stable during the mission in all bands but for band 3 (Si:As). Dark currents and responses were found to be higher in the first hours following the start of the science window, especially in band 2 (Si:Ga). We have studied the impacts of cosmic rays and radiation belt particles on the SWS detectors, as well as of the only large solar proton event on November 6, 1997, that occurred during the ISO mission (operated during solar minimum). The observed glitch rates in all SWS bands are found to be between 2 and 4 times higher than the value predicted by the CREME96 model for the cosmic ray flux in the period considered. The bands that registered the highest glitch rates showed also a correlation with the electron fluxes measured on the GOES 9 spacecraft. From the distribution of glitch heights (voltage jumps in the detector signal), we have derived the deposited energy distributions of the particles hits. Our results lead to the conclusion that secondary particles produced in the shield and the detectors contributed at least as much as cosmic rays to the observed glitch rate. The effects on the detectors of the November 6, 1997 event, which caused that all observations in a revolution were declared failed, are described in detail.

Heras, A. M.; Wieprecht, E.; Feuchtgruber, H.; Lahuis, F.; Leech, K.; Lorente, R.; Morris, P.; Salama, A.; Vandenbussche, B.

2000-08-01

210

Gamma spectroscopic measurements using the PID350 pixelated CdTe radiation detector  

E-print Network

Spectroscopic measurements are presented using the PID350 pixelated gamma radiation detectors. A high-speed data acquisition system has been developed in order to reduce the data loss during the data reading in case of a high flux of photons. A data analysis framework has been developed in order to improve the resolution of the acquired energy spectra, using specific calibration parameters for each PID350's pixel. Three PID350 detectors have been used to construct a stacked prototype system and spectroscopic measurements have been performed in order to test the ability of the prototype to localize radioactive sources.

K. Karafasoulis; K. Zachariadou; S. Seferlis; I. Papadakis; D. Loukas; C. Lambropoulos; C. Potiriadis

2010-11-15

211

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

NASA Technical Reports Server (NTRS)

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

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

1975-01-01

212

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

213

Advanced data readout technique for Multianode Position Sensitive Photomultiplier Tube applicable in radiation imaging detectors  

SciTech Connect

Most of the best performing PSPMT tubes from Hamamatsu and Burle are designed with a pad-matrix anode layout. However, for obtaining a high resolution, a small-sized anode photomultiplier tubes are preferable; these tubes may have 64, 256 or 1024 anodes per tube. If the tubes are used in array to get a larger area detector, the number of analog channels may range from hundreds to thousands. Multichannel analog readout requires special electronics ICs, ASICs etc., which are attached to multichannel DAQ system. As a result, the data file and data processing time will be increased. Therefore, this readout could not be performed in a small project. Usually, most of radiation imaging applications allow the use of analog data processing in front-end electronics, significantly reducing the number of the detector's output lines to data acquisition without reducing the image quality. The idea of pad-matrix decoupling circuit with gain correction was invented and intensively tested in JLab. Several versions of PSPMT readout electronics were produced and studied. All developments were done and optimized specifically for radiation imaging projects. They covered high resolution SPECT, high speed PET, fast neutron imaging, and single tube and multi tube array systems. This paper presents and discusses the summary of the observed results in readout electronics evaluation with different PSPMTs and radiation imaging systems, as well as the advantages and limitations of the developed approach to radiation imaging detectors readout.

V. Popov

2011-01-01

214

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

SciTech Connect

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

Hennig, Wolfgang

2012-06-22

215

Single-detector searches for a stochastic background of gravitational radiation  

E-print Network

We propose a data processing technique that allows searches for a stochastic background of gravitational radiation with data from a single detector. Our technique exploits the difference between the coherence time of the gravitational wave (GW) signal and that of the instrumental noise affecting the measurements. By estimating the auto-correlation function of the data at an off-set time that is longer than the coherence time of the noise {\\underbar {but}} shorter than the coherence time of the GW signal, we can effectively enhance the power signal-to-noise ratio (SNR) by the square-root of the integration time. The resulting SNR is comparable in magnitude to that achievable by cross-correlating the data from two co-located and co-aligned detectors whose noises are uncorrelated. Our method is general and it can be applied to data from ground- and space-based detectors, as well as from pulsar timing experiments.

Tinto, Massimo

2012-01-01

216

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

217

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

NASA Astrophysics Data System (ADS)

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

Acconcia, T. V.; Agócs, A. G.; Barile, F.; Barnaföldi, G. G.; Bellwied, R.; Bencédi, G.; Bencze, G.; Berényi, D.; Boldizsár, L.; Chattopadhyay, S.; Chinellato, D. D.; Cindolo, F.; Cossyleon, K.; Das, D.; Das, K.; Das-Bose, L.; Dash, A. K.; D'Ambrosio, S.; De Cataldo, G.; De Pasquale, S.; Di Bari, D.; Di Mauro, A.; Futó, E.; Garcia-Solis, E.; Hamar, G.; Harton, A.; Iannone, G.; Jimenez, R. T.; Kim, D. W.; Kim, J. S.; Knospe, A.; Kovács, L.; Lévai, P.; Markert, C.; Martinengo, P.; Molnár, L.; Nappi, E.; Oláh, L.; Pai?, G.; Pastore, C.; Patimo, G.; Patino, M. E.; Peskov, V.; Pinsky, L.; Piuz, F.; Pochybová, S.; Sgura, I.; Sinha, T.; Song, J.; Takahashi, J.; Timmins, A.; Van Beelen, J. B.; Varga, D.; Volpe, G.; Weber, M.; Xaplanteris, L.; Yi, J.; Yoo, I.-K.

2014-12-01

218

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

SciTech Connect

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

Rebisz-Pomorska, M.; Tromson, D.; Bergonzo, P. [CEA, LIST, Diamond Sensors Laboratory, F-91191 Gif-sur-Yvette (France); Isambert, A. [Institut Gustave Roussy (IGR), 94805 Villejuif (France); Marczewska, B. [Institute of Nuclear Physics, Polish Academy of Sciences (IFJ PAN), 31-342 Krakow (Poland)

2009-10-15

219

Signal and noise of diamond pixel detectors at high radiation fluences  

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

220

Temperature dependence of the radiation induced change of depletion voltage in silicon PIN detectors  

SciTech Connect

The silicon microstrip detectors that will be used in the SDC experiment at the Superconducting Super Collider (SSC) will be exposed to very large fluences of charged particles, neutrons, and gammas. The authors present a study of how temperature affects the change in the depletion voltage of silicon PIN detectors damaged by radiation. They study the initial radiation damage and the short-term and long-term annealing of that damage as a function of temperature in the range from {minus}10{degrees}C to +50{degrees}C, and as a function of 800 MeV proton fluence up to 1.5 {times} 10{sup 14} p/cm{sup 2}. They express the pronounced temperature dependencies in a simple model in terms of two annealing time constants which depend exponentially on the temperature.

Ziock, H.J.; Holzscheiter, K.; Morgan, A.; Palounek, A.P.T. [Los Alamos National Lab., NM (United States); Ellison, J.; Heinson, A.P.; Mason, M.; Wimpenny, S.J. [Univ. of California, Riverside, CA (United States); Barberis, E.; Cartiglia, N.; Grillo, A.; O`Shaughnessy, K.; Rahn, J.; Rinaldi, P.; Rowe, W.A.; Sadrozinski, H.F.W.; Seiden, A.; Spencer, E.; Webster, A.; Wichmann, R.; Wilder, M. [Univ. of California, Santa Cruz, CA (United States). Santa Cruz Inst. for Particle Physics; Frautschi, M.A.; Matthews, J.A.J.; McDonald, D.; Skinner, D. [Univ. of New Mexico, Albuquerque, NM (United States); Coupal, D.; Pal, T. [Superconducting Super Collider Lab., Dallas, TX (United States)

1993-11-01

221

Investigation of efficient termination structure for improved breakdown properties of semiconductor radiation detectors  

SciTech Connect

Efficiency of a new junction termination structure for improvement of breakdown properties of semiconductor radiation detectors is investigated. The structure consists of a diffused resistor winding around the active junction in a spiral fashion. The current flow through the spiral enables controlled potential distribution along the spiral turns and thus controlled depletion spreading from the main junction, efficiently preventing premature avalanche breakdown. Both multiple guard-ring structures and spiral junction termination structures have shown good breakdown properties typically three to five times higher than breakdown voltages of diodes without junction termination. The breakdown voltages of spiral junction termination structures are only weakly influenced by changes in substrate doping concentration caused by neutron irradiation. They can thus be considered for termination of future semiconductor radiation detectors.

Krizaj, D.; Resnik, D.; Vrtacnik, D.; Amon, S. [Univ. of Ljubljana (Slovenia). Faculty of Electrical Engineering] [Univ. of Ljubljana (Slovenia). Faculty of Electrical Engineering; Cindro, V. [Jozef Stefan Inst., Ljubljana (Slovenia)] [Jozef Stefan Inst., Ljubljana (Slovenia)

1998-06-01

222

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

223

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

PubMed

Cosmic radiation bombards us at high altitude by ionizing particles. The radiation environment is a complex mixture of charged particles of solar and galactic origin, as well as of secondary particles produced in interaction of the galactic cosmic particles with the nuclei of atmosphere of the Earth. The radiation field at aircraft altitude consists of different types of particles, mainly photons, electrons, positrons and neutrons, with a large energy range. The non-neutron component of cosmic radiation dose aboard ATR 42 and A 320 aircrafts (flight level of 8 and 11 km, respectively) was measured with TLD-100 (LiF:Mg,Ti) detectors and the Mini 6100 semiconductor dosimeter. The estimated occupational effective dose for the aircraft crew (A 320) working 500 h per year was 1.64 mSv. Other experiments, or dose rate measurements with the neutron dosimeter, consisting of LR-115 track detector and boron foil BN-1 or 10B converter, were performed on five intercontinental flights. Comparison of the dose rates of the non-neutron component (low LET) and the neutron one (high LET) of the radiation field at the aircraft flight level showed that the neutron component carried about 50% of the total dose. The dose rate measurements on the flights from the Middle Europe to the South and Middle America, then to Korea and Japan, showed that the flights over or near the equator region carried less dose rate; this was in accordance with the known geomagnetic latitude effect. PMID:17600597

Vukovi?, B; Radoli?, V; Miklavci?, I; Poje, M; Varga, M; Planini?, J

2007-01-01

224

Miniaturized black body radiator for IR-detector calibration — Design and development  

Microsoft Academic Search

Nowadays very often IR-thermography is used to analyze the temperature on electronic device surfaces. To measure the absolute surface temperature correctly, the IR-camera detector has to be calibrated with an corresponding evaluation software using a black body calibration device. Commercially available black radiators are heavyweight and a calibration of macro-lenses is not possible due to mismatch of the macro lens

R. Schacht; C. Gerner; T. Nowak; D. May; B. Wunderle; B. Michel

2010-01-01

225

Proximity focusing RICH with flat panel PMT as photon detector and aerogel as radiator  

Microsoft Academic Search

Using aerogel as radiator and 64-channel flat panel multi-anode PMTs (Hamamatsu H8500) for photon detection, a proximity focusing Cherenkov ring imaging detector has been constructed and tested in the KEK ?2 beam. The single photon resolution obtained in the tests (typically around 14mrad) is well approximated by estimates of contributions from pixel size and emission point uncertainty. The number of

P. Krizan; I. Adachi; S. Fratina; S. Fukushima; A. Gorisek; T. Iijima; H. Kawai; H. Konishi; S. Korpar; Y. Kozakai; T. Matsumoto; Y. Mazuka; S. Nishida; S. Ogawa; S. Ohtake; R. Pestotnik; S. Saitoh; T. Seki; T. Sumiyoshi; Y. Uchida; Y. Unno; S. Yamamoto

2005-01-01

226

Study of the radiation hardness of CsI(Tl) crystals for the BELLE detector  

Microsoft Academic Search

The radiation hardness of prototype CsI(Tl) crystals has been tested for the barrel electromagnetic calorimeter for the BELLE detector of the KEK B factory. Although samples made by one of the producers were found to be soft under irradiation, the problem was quickly improved when this information was fed back. All the tested crystals were found to meet our requirement.The

K. Kazui; A. Watanabe; S. Osone; B. G Cheon; M. Fukushima; H. Hayashii; X. Q Hu; S. Ichizawa; S. Igarashi; H. Ikeda; K. Kaneyuki; M. H Lee; K. Miyabayashi; S. Noguchi; H. Sagawa; A. Satpathy; R. Suzuki; K. Tamai; T. Tsukamoto; Y. Watanabe; X. C Zhong

1997-01-01

227

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

Microsoft Academic Search

We describe the design considerations and construction techniques of a large cylindrical transition radiation detector (TRD), 296 cm long and 311.4 cm in diameter, for the VENUS experiment at the e+e+ storage ring, TRISTAN. The design is based on measurements by using test chambers with e\\/pi beams and X-ray sources. The test results will be fully described. The TRD contains

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

1992-01-01

228

Semi-insulating LEC GaAs as a material for radiation detectors: materials science issues  

Microsoft Academic Search

Semi-insulating (SI) GaAs is now being reconsidered as a promising material for radiation detectors, mostly due to greatly improved quality of the material. In this paper we shall describe the properties of the state-of-the-art SI GaAs crystals grown by LEC method as relevant for such applications. Specifically, we shall concentrate on the assessment of the spectra and density of residual

A. V. Markov; M. V. Mezhennyi; A. Y. Polyakov; N. B. Smirnov; A. V. Govorkov; V. K. Eremin; E. M. Verbitskaya; V. N. Gavrin; Y. P. Kozlova; Y. P. Veretenkin; T. J. Bowles

2001-01-01

229

Radiation hardness test of FSSR, a multichannel, mixed signal chip for microstrip detector readout  

Microsoft Academic Search

The Fermilab Silicon Strip Readout (FSSR) chip is a 128-channel, mixed signal circuit, which was designed for processing the signals from the microstrip detectors of the BTeV experiment at the Tevatron collider. The design was carried out in a 0.25 mum CMOS technology, whose intrinsic radiation hardness is supposed to satisfy the application requirements. Such features were further improved by

Lodovico Ratti; Massimo Manghisoni; V. Re; G. Traversi; A. Candelori

2005-01-01

230

Monte Carlo Study of a Mosfet Detector Response Applied to X-Ray Microbeam Radiation Therapy  

NASA Astrophysics Data System (ADS)

EGS4 Monte Carlo calculations of the dose deposited by array of microbeams, used for the Microbeam Radiation Therapy technique, are presented. The sensitivity of the results to the experimental parameters (incident beam energy, beam array dimensions and spacing) has been assessed. The effects of the photon beam polarization and energy cut-off have also been investigated. The response of a Silicon MOSFET detector of micrometric dimensions, placed inside a phantom made of two homogeneous media (water and PMMA), has been simulated.

de Felici, M.; Felici, R.; Sanchez Del Rio, M.; Dilmanian, A.; Ferreo, C.

2004-07-01

231

Development of radiation tolerant semiconductor detectors for the Super-LHC  

Microsoft Academic Search

The envisaged upgrade of the Large Hadron Collider (LHC) at CERN towards the Super-LHC (SLHC) with a 10 times increased luminosity of 1035cm?2s?1 will present severe challenges for the tracking detectors of the SLHC experiments. Unprecedented high radiation levels and track densities and a reduced bunch crossing time in the order of 10ns as well as the need for cost

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

2005-01-01

232

Unipolar charge sensing using Frisch grid technique for amorphous selenium radiation detectors  

Microsoft Academic Search

We investigate amorphous Selenium Frisch-grid detector design to improve the spectral performance, reliability of single photon detection, and image lag for radiation imaging and detection. Incomplete charge collection due to the low electron mobility in amorphous Selenium results in depth-dependent signal variations. The slow signal rise-time for the portion of the induced charge due to electron-movement towards the anode and

A. H. Goldan; K. S. Karim

2008-01-01

233

Variable filtered photographic film as a radiation detector for environmental radiation monitoring  

NASA Astrophysics Data System (ADS)

Environmental radiation is an ionising radiation that present in the natural environment which mostly originates from cosmic rays and radionuclide agents in the environment. This may lead the population to be exposed to the radiation. Therefore, the environmental radiation needs to be observed cautiously to minimize the impact of radiation. However, there is no specific or proper monitoring device that provides an outdoor environmental radiation monitoring. Hence, a new outdoor environmental radiation monitoring device was developed. A photographic film has been chosen as a dosimeter. The purpose of this study was to prove the covered photographic film attached with variable filter can be used to develop environmental radiation monitoring device to detect the ionising radiation. The filter used was variable thickness of plastic, aluminium (Al) and lead (Pb). The result from the study showed that the mean optical density (OD) values for medium speed film are in the range 0.41 to 0.73, and for fast speed film the OD values are in the range 0.51 to 1.35. The OD values decreased when the filter was attached. This has proven that the photographic film can be used to detect radiation and fast speed film was more sensitive compared to medium speed film.

Majid, Zafri Azran Abdul; Junet, Laila Kalidah; Hazali, Norazlanshah; Abdullah, Abdul Adam; Hanafiah, Megat Ahmad Kamal Megat

2013-05-01

234

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

235

Study of resistive micromegas detectors in a mixed neutron and photon radiation environment  

NASA Astrophysics Data System (ADS)

The Muon ATLAS Micromegas Activity (MAMMA) focuses on the development and testing of large-area muon detectors based on the bulk-Micromegas technology. These detectors are candidates for the upgrade of the ATLAS Muon System in view of the luminosity upgrade of Large Hadron Collider at CERN (sLHC). They will combine trigger and precision measurement capability in a single device. A novel protection scheme using resistive strips above the readout electrode has been developed. The response and sparking properties of resistive Micromegas detectors were successfully tested in a mixed (neutron and gamma) high radiation environment supplied by the Tandem accelerator at the N.C.S.R. Demokritos in Athens. Monte-Carlo studies have been employed to study the effect of 5.5 MeV neutrons impinging on Micromegas detectors. The response of the Micromegas detectors on the photons originating from the inevitable neutron inelastic scattering on the surrounding materials of the experimental facility was also studied.

Alexopoulos, T.; Iakovidis, G.; Tsipolitis, G.

2012-05-01

236

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

237

Particle Detectors  

NASA Astrophysics Data System (ADS)

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

Grupen, Claus; Shwartz, Boris

2008-03-01

238

Particle Detectors  

NASA Astrophysics Data System (ADS)

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

Grupen, Claus; Shwartz, Boris

2011-09-01

239

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

240

Radiation Hardness of Silicon Detectors Manufactured on Epitaxial Material and FZ Bulk Enriched with Oxygen, Carbon, Tin and Platinum  

NASA Astrophysics Data System (ADS)

Recent results on the radiation hardness of silicon detectors fabricated on epitaxial and float zone bulk silicon enriched by various impurities, such as carbon, oxygen, tin and platinum are reported. A new methodology of measurements of electrical properties of the devices has been utilized in the experiment. It has been shown that in the case of irradiation by protons, oxygen enriched silicon has better radiation hardness than standard float zone silicon. The carbon enriched silicon detectors, on the other hand, exhibited significantly inferior radiation hardness compared to standard detectors. This study shows for the first time, a violation of the widely used narmalization technique of the various particle irradiations by NIEL coefficients. The study has been carried out in the framework of the RD48 (ROSE) collaboration, which studies the radiation hardening of silicon detectors.

Ruzin, A.; Casse, G.; Glaser, M.; Lemeilleur, F.; Talamonti, R.; Watts, S.; Zanet, A.; ROSE Collaboration-RD48

1999-08-01

241

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

NASA Astrophysics Data System (ADS)

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

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

242

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

SciTech Connect

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

Han, Hetong [Northwest Institute of Nuclear Technology, NINT, Xi'an 710024, Shaanxi (China) [Northwest Institute of Nuclear Technology, NINT, Xi'an 710024, Shaanxi (China); School of Nuclear Science and Technology, Xi'an Jiaotong University, XJTU, Xi'an 710049, Shaanxi (China); Zhang, Zichuan; Weng, Xiufeng; Liu, Junhong; Zhang, Kan; Li, Gang [Northwest Institute of Nuclear Technology, NINT, Xi'an 710024, Shaanxi (China)] [Northwest Institute of Nuclear Technology, NINT, Xi'an 710024, Shaanxi (China); Guan, Xingyin [School of Nuclear Science and Technology, Xi'an Jiaotong University, XJTU, Xi'an 710049, Shaanxi (China)] [School of Nuclear Science and Technology, Xi'an Jiaotong University, XJTU, Xi'an 710049, Shaanxi (China)

2013-07-15

243

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

244

The iQID camera: An ionizing-radiation quantum imaging detector  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

245

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

246

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>0.5 GeV. 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 0.8×1034 cm-2 s-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

247

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

248

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

249

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

DOEpatents

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

Hermes, Robert E. (White Rock, NM)

2002-01-01

250

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

SciTech Connect

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

Li, Z. [Brookhaven National Lab., Upton, NY (United States); Eremin, V.; Ilyashenko, I.; Ivanov, A.; Verbitskaya, E. [Russian Academy of Sciences, St. Petersburg (Russian Federation). Ioffe Physico-Technical Inst.; CERN RD-48 ROSE Collaboration

1997-12-01

251

Radiation effects on the silicon semiconductor detectors for the ASTRO-H mission  

NASA Astrophysics Data System (ADS)

Hard X-ray Imager (HXI) and Soft Gamma-ray Detector (SGD) onboard the 6th Japanese X-ray satellite, ASTRO-H, utilize double-sided silicon strip detectors (DSSD) and pixel array-type silicon sensors (Si-pad), respectively. The DSSD with a 3.4 cm×3.4 cm area has an imaging capability in the lower energy band for the HXI covering 5-80 keV. The Si-pad consists of 16×16 pixels with a 5.4 cm×5.4 cm area and measures a photon direction with the Compton kinematics in 10-600 keV. Since the ASTRO-H will be operated in a low earth orbit, these detectors will be damaged by irradiation of cosmic-ray protons mainly in the South Atlantic Anomaly. In order to evaluate damage effects of the sensors, we have carried out irradiation tests with 150 MeV proton beams and 60Co gamma-rays with a total dose of 10-20 years irradiation level. In both experiments, the leakage current has increased by ˜0.2--1.1 nA/cm2 under an expected operation temperature at -15 °C, which resulted in the noise level within a tolerance of 20 years. In this report, we present a summary of the basic performance of silicon detectors, and radiation effects on them by the irradiation tests.

Hayashi, Katsuhiro; Park, InChun; Dotsu, Kyohei; Ueno, Issei; Nishino, Sho; Matsuoka, Masayuki; Yasuda, Hajimu; Fukazawa, Yasushi; Ohsugi, Takashi; Mizuno, Tsunefumi; Takahashi, Hiromitsu; Ohno, Masanori; Endo, Satoru; Tanaka, Takaaki; Tajima, Hiroyasu; Kokubun, Motohide; Watanabe, Shin; Takahashi, Tadayuki; Nakazawa, Kazuhiro; Uchihori, Yukio; Kitamura, Hisashi

2013-01-01

252

New detector technology to detect and determine the angle of arrival of collimated radiation  

NASA Astrophysics Data System (ADS)

Miniaturized digital High Angular Resolution Laser Irradiation Detector (HARLIDTM) modules have been developed by the Defence Research Establishment Valcartier in collaboration with EG&G Optoelectronics Canada. These modules are designed to locate a collimated beam of radiation, such as a laser, within +/- 1 degree(s) over a 90 degree(s) field of view either in azimuth or elevation. There are presently two versions of HARLID: the 1-band HARLID which is based on Si detectors and is functional within the range of 0.45 to 1.1 micrometers ; and the 2-band HARLID based on Si/InGaAs detectors and is functional within the range of 0.45 to 1.70 micrometers . The principle of operation of this new patented module is based on the use of a Gray code mask to encode the angle of arrival of a laser beam. Military and civilian applications fields include defensive aid suites (Laser Warning Receivers) and platform guidance, alignment and positioning aids, where high angular precision is required. There are other laser detectors on the market, but HARLID has emerged, through laboratory testing and comparative field trials, to be one of the best performers, selling at the lower cost and having the lowest integration encumbrance.

Cantin, Andre; Dubois, Jacques

1998-09-01

253

GaSe and GaTe anisotropic layered semiconductors for radiation detectors  

NASA Astrophysics Data System (ADS)

High quality detector grade GaSe and GaTe single crystals have been grown by a modified vertical Bridgman technique using high purity Ga (7N) and in-house zone refined (ZR) precursor materials (Se and Te). A state-of-the-art computer model, MASTRAPP, is used to model heat and mass transfer in the Bridgman growth system and to predict the stress distribution in the as-grown crystals. The model accounts for heat transfer in the multiphase system, convection in the melt, and interface dynamics. The crystals harvested from ingots of 8-10 cm length and 2.5 cm diameter, have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, low temperature photoluminescence (PL), atomic force microscopy (AFM), and optical absorption/transmission measurements. Single element devices up to 1 cm2 in area have been fabricated from the crystals and tested as radiation detectors by measuring current-voltage (I-V) characteristics and pulse height spectra using 241Am source. The crystals have shown high promise as nuclear detectors with their high dark resistivity (>=10 9 ? .cm), good charge transport properties (?? e ~ 1.4x10 -5 cm2/V and ?? h ~ 1.5x10 -5 cm2/V), and relatively good energy resolution (~4% energy resolution at 60 keV). Details of numerical modeling and simulation, detector fabrication, and testing using a 241Am energy source (60 keV) is presented in this paper.

Mandal, Krishna C.; Choi, Michael; Kang, Sung Hoon; Rauh, R. David; Wei, Jiuan; Zhang, Hui; Zheng, Lili; Cui, Y.; Groza, M.; Burger, A.

2007-09-01

254

Performance of semi-insulating GaAs-based radiation detectors: Role of key physical parameters of base materials  

NASA Astrophysics Data System (ADS)

In this work, the requirements of detector-grade semiconductor materials for radiation detectors, applicable in X-ray digital radiology, are identified. The study includes 12 various bulk semi-insulating (SI) GaAs single crystals grown by LEC and VGF methods, undoped and Cr-doped, obtained from 8 different suppliers. Conductivity, Hall, glow discharge mass spectrometry (GDMS), etch pit density (EPD), scanning electron beam induced current (S-EBIC), X-ray and laser scattering tomography (LST) techniques are used for the bulk SI GaAs material evaluation. The radiation detectors fabricated on these SI GaAs single crystals have been characterized by capacitance methods and their performances have been evaluated from detected pulse height spectra of 57Co. The correlation between the physical characteristics of the base materials and the performance of the detectors is demonstrated and discussed. Key detector-grade SI GaAs parameters, useful for material evaluation, are identified.

Dubecký, František; Ferrari, Claudio; Korytár, Dušan; Gombia, Enos; Ne?as, Vladimír

2007-06-01

255

Charged-particle induced radiation damage of a HPGe gamma-ray detector during spaceflight  

NASA Astrophysics Data System (ADS)

The Mars Observer spacecraft was launched on September 26, 1992 with a planned arrival at Mars after an 11-month cruise. Among the scientific instruments carried on the spacecraft was a Gamma-Ray Spectrometer (GRS) experiment to measure the composition of Mars. The GRS used a passively cooled high-purity germanium detector for measurements in the 0.2-10MeV region. The sensor was a closed-end co-axial detector, 5.5cm diameter by 5.5cm long, and had an efficiency along its axis of 28% at 1332keV relative to a standard NaI(Tl) detector. The sensor was surrounded by a thin (0.5cm) plastic charged-particle shield. This was the first planetary mission to use a cooled Ge detector. It was expected that the long duration in space of three years would cause an increase in the energy resolution of the detector due to radiation damage and could affect the expected science return of the GRS. Shortly before arrival, on August 21, 1993, contact was lost with the spacecraft following the pressurization of the propellent tank for the orbital-insertion rocket motor. During much of the cruise to Mars, the GRS was actively collecting background data. The instrument provided over 1200h of data collection during periods of both quiescent sun and solar flares. From the charged particle interactions in the shield, the total number of cosmic ray hits on the detector could be determined. The average cosmic ray flux at the MO GRS was about 2.5cm-2s-1. The estimated fluence of charged particles during cruise was about 108 particles cm-2 with 31% of these occurring during a single solar proton event of approximately 10 days duration. During cruise, the detector energy resolution determined from a background gamma-ray at 1312keV degraded from 2.4keV full-width at half-maximum shortly after launch to 6.4keV 11 months later. This result agrees well with measurements from ground-based accelerator irradiations (at 1.5GeV) on a similar size detector.

Evans, L. G.; Starr, R.; Brückner, J.; Boynton, W. V.; Bailey, S. H.; Trombka, J. I.

1999-02-01

256

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

NASA Technical Reports Server (NTRS)

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

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

2014-01-01

257

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

PubMed

We propose to study the radiation environment on board different flight vehicles: cosmos-type satellites, orbital stations, Space Shuttles and civil (sonic and supersonic) aircraft. These investigations will be carried out with single type of passive detector, namely, nuclear photoemulsions (NPE) with adjustable threshold of particle detection within broad range of linear energy transfer (LET) that is done by means of the technique of selective development of NPE exposed in space. These investigations will allow, one to determine: integral spectra of LET of charged particles of cosmic ray (CR) over a wide range from 2.0 to 5 x 10(4) MeV/cm in biological tissue; differential energy spectra of fast neutrons (1-20 MeV); estimation of absorbed and equivalent doses from charged and neutral component CR; charge and energy spectra of low energy nuclei (E < or = 100 MeV) with Z > or = 2 having in view the extreme hazard radiation to biological objects and microelectronic schemes taken on board inside and outside of these different flight vehicles with exposures from several days to several months. The investigation of radiation environment on board the airplanes depending on the flight parameters will be conducted using emulsions of different sensitivity without any controlling of threshold sensitivity (Akopova et al., 1996). The proposed detector can be used in the joint experiments on the new International Cosmic Station "Alpha". PMID:11542906

Akopova, A B

1998-01-01

258

Development of High Energy Particle Detector for the Study of Space Radiation Storm  

NASA Astrophysics Data System (ADS)

Next Generation Small Satellite-1 (NEXTSat-1) is scheduled to launch in 2017 and Instruments for the Study of Space Storm (ISSS) is planned to be onboard the NEXTSat-1. High Energy Particle Detector (HEPD) is one of the equipment comprising ISSS and the main objective of HEPD is to measure the high energy particles streaming into the Earth radiation belt during the event of a space storm, especially, electrons and protons, to obtain the flux information of those particles. For the design of HEPD, the Geometrical Factor was calculated to be 0.05 to be consistent with the targets of measurement and the structure of telescope with field of view of 33.4°? was designed using this factor. In order to decide the thickness of the detector sensor and the classification of the detection channels, a simulation was performed using GEANT4. Based on the simulation results, two silicon detectors with 1 mm thickness were selected and the aluminum foil of 0.05 mm is placed right in front of the silicon detectors to shield low energy particles. The detection channels are divided into an electron channel and two proton channels based on the measured LET of the particle. If the measured LET is less than 0.8 MeV, the particle belongs to the electron channel, otherwise it belongs to proton channels. HEPD is installed in the direction of 0°?,45°?,90°? against the along-track of a satellite to enable the efficient measurement of high energy particles. HEPD detects electrons with the energy of 0.1 MeV to several MeV and protons with the energy of more than a few MeV. Thus, the study on the dynamic mechanism of these particles in the Earth radiation belt will be performed.

Jo, Gyeong-Bok; Sohn, Jongdae; Choi, Cheong Rim; Yi, Yu; Min, Kyoung-Wook; Kang, Suk-Bin; Na, Go Woon; Shin, Goo-Hwan

2014-09-01

259

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

260

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

261

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

PubMed

A CdZnTe electro-optic radiation detector was used to calibrate nuclear reactor pulses. The standard configuration of the Pockels cell has collimated light passing through an optically transparent CdZnTe crystal located between crossed polarizers. The transmitted light was focused onto an IR sensitive photodiode. Calibrations of reactor pulses were performed using the CdZnTe Pockels cell by measuring the change in the photodiode current, repeated 10 times for each set of reactor pulses, set between 1.00 and 2.50 dollars in 0.50 increments of reactivity. PMID:22236603

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

2012-07-01

262

Radiation effect on pn-SiC diode as a detector  

Microsoft Academic Search

We studied radiation tolerance of pn junction 6H-SiC (silicon carbide) diodes on electrical properties and detector performance for alpha particles. Three pn-SiC diodes were irradiated with gamma-rays at doses (60Co source) up to 2.5MGy and two diodes were irradiated with beta-rays (2MeV) at fluences up to 1×1015 electrons\\/cm2. The ideality factors ?, which are estimated from current–voltage (I–V) characteristics of

Akimasa Kinoshita; Motohiro Iwami; Ken-Ichi Kobayashi; Itsuo Nakano; Reisaburo Tanaka; Tomihiro Kamiya; Akihiko Ohi; Takeshi Ohshima; Yasutaka Fukushima

2005-01-01

263

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

264

Detectors & Other Instrumentation for Research in Environmental Chemistry & Heterogeneous Catalysis at the Stanford Synchrotron Radiation Laboratory  

SciTech Connect

OAK 270 The Stanford Synchrotron Radiation Laboratory (SSRL) is a national user facility used by an international body of scientists to perform x-ray spectroscopy and x-ray scattering research using our high-intensity x-ray beam lines. The primary objectives for DOE grant DE FG03 96ER14650 was to leverage these facilities by providing advanced detectors and instrumentation for use by visiting scientists at the new beam line 11-2, which is dedicated to environmental sciences, and at other SSRL beam lines used for environmental sciences research. All items are now available for use at various SSRL beam lines.

Brown, Gordon

2003-01-21

265

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

266

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

SciTech Connect

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.

James, Ralph (BNL Nonproliferation and National Security Department) [BNL Nonproliferation and National Security Department

2010-08-18

267

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

PubMed

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

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

2014-10-01

268

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

269

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

270

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

271

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

NASA Technical Reports Server (NTRS)

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

Baily, N. A.

1973-01-01

272

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

273

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

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

274

Applications of pixellated GaAs X-ray detectors in a synchrotron radiation beam  

NASA Astrophysics Data System (ADS)

Hybrid semiconductor pixel detectors are being investigated as imaging devices for radiography and synchrotron radiation beam applications. Based on previous work in the CERN RD19 and the UK IMPACT collaborations, a photon counting GaAs pixel detector (PCD) has been used in an X-ray powder diffraction experiment. The device consists of a 200 ?m thick SI-LEC GaAs detector patterned in a 64×64 array of 170 ?m pitch square pixels, bump-bonded to readout electronics operating in single photon counting mode. Intensity peaks in the powder diffraction pattern of KNbO 3 have been resolved and compared with results using the standard scintillator, and a PCD predecessor (the ?3). The PCD shows improved speed, dynamic range, 2-D information and comparable spatial resolution to the standard scintillator based systems. It also overcomes the severe dead time limitations of the ?3 by using a shutter based acquisition mode. A brief demonstration of the possibilities of the system for dental radiography and image processing are given, showing a marked reduction in patient dose and dead time compared with film.

Watt, J.; Bates, R.; Campbell, M.; Mathieson, K.; Mikulec, B.; O'Shea, V.; Passmore, M.-S.; Schwarz, C.; Smith, K. M.; Whitehill, C.; XIMAGE Project

2001-03-01

275

Parameter estimation and optimal design of thermal radiation detectors using engineering prototypes and numerical models  

NASA Astrophysics Data System (ADS)

Scientists at NASA's Langley Research Center, in collaboration with researchers at Virginia Tech, are developing the next generation of thermal radiation detectors composed of new space-age materials, including carbon-doped Larc-Si and aerogels. In order to accurately model and design these detectors, it is necessary to determine the in situ thermoelectric properties of these new materials, including thin-film effects and contact resistance. The authors present an approach to determine these properties through the use of simultaneous parameter estimation methods in which experimental results obtained from detector prototypes are compared with results predicted from analytical models. Parametric values are varied using an optimization method to minimize the least-squares error between the experimental and model results. A numerical study is presented to validate the use of this approach. Simulated experimental results were produced using a model based on nominal parameter values. These results were then introduced into a parameter estimation algorithm that was able to recover the parameter values without the benefit of a priori knowledge about the material properties. Genetic algorithms, stochastic hill climbers, and a hybrid of the two methods were investigated for use in parameter estimation.

Sorensen, Ira J.; Mahan, J. Robert; Barry, Mamadou Y.; Kist, Edward H., Jr.

1999-12-01

276

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

277

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

278

Optimizing the SNR from a radiation detector with delay-line position-sensing electrodes  

NASA Astrophysics Data System (ADS)

In order to image the radiation field, instruments measure the position of interaction of the incident quanta, a task typically accomplished by partitioning the detector or its readout. We previously performed a fundamental investigation of the electrode design and pulse shape analysis routines required to optimize the detector's position resolution, when limited by both temporal and carrier uncertainties. If the transmission-line electrode structure is balanced at the frequencies of interest, then the time difference between the pulses at the readout end of a serpentine delay-line electrode structure can be used to measure the position at which the charge was collected. In this paper, we describe the fabrication techniques used to overcome the two greatest limitations of the early detectors, namely, high leakage currents and high propagation losses. In the following, we describe, through both models and measurements, the means by which: (a) one can achieve impedance matching by conversion of the electrode into a 50 ? asymmetric strip line and (b) one can minimize the propagation losses by the use of thick high-conductivity electrodes and the use of low-loss dielectrics (BaSrTiO 3 and BaTiO 3), as a part of an asymmetric strip line design. In order to accomplish low leakage designs, we describe the fabrication of delay-line PIN devices with metal field plates (MFPs) and multiple floating guard rings.

Jeong, Manhee; Hammig, Mark D.; Ramadoss, Subhashree

2011-10-01

279

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

280

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

281

Radiation tolerance of prototype BTeV pixel detector readout chips  

SciTech Connect

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

Gabriele Chiodini et al.

2002-07-12

282

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

283

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

284

X-ray radiation detectors of ``scintillator-photoreceiving device type'' for industrial digital radiography with improved spatial resolution  

Microsoft Academic Search

Main types of photoreceivers used in X-ray digital radiography systems are luminescent screens that transfer the optical image onto charge collection instruments, which require cooling, and semiconductor silicon detectors, which limit the contrast sensitivity. We have developed and produced X-ray radiation detectors of ``scintillator-photoreceiving device'' (S-PRD) type, which are integrally located on the inverse side of the photodiode (PD). The

V. D. Ryzhykov; O. K. Lysetska; O. D. Opolonin; D. N. Kozin

2003-01-01

285

X-ray radiation detectors of “scintillator-photoreceiving device type” for industrial digital radiography with improved spatial resolution  

Microsoft Academic Search

Main types of photoreceivers used in X-ray digital radiography systems are luminescent screens that transfer the optical image onto charge collection instruments, which require cooling, and semiconductor silicon detectors, which limit the contrast sensitivity. We have developed and produced X-ray radiation detectors of “scintillator-photoreceiving device” (S-PRD) type, which are integrally located on the inverse side of the photodiode (PD). The

V. D. Ryzhykov; O. K. Lysetska; O. D. Opolonin; D. N. Kozin

2003-01-01

286

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

287

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

288

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

SciTech Connect

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

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

1998-11-07

289

Radiation damage due to pions and protons in SI-GaAs and their influence on the detector performance  

NASA Astrophysics Data System (ADS)

The bulk damage (namely the introduction rate of the arsenic antisite As Ga and its ionization ratio) was determined as a function of the non-ionizing energy loss (NIEL) of hadrons in semi-insulating GaAs. The study was performed using near-infrared absorption on 23 GeV proton and 192 MeV pion irradiated, Liquid Encapsulated Czochralski (LEC) grown GaAs. Together with the detector performance as a function of the radiation level, the results are used to explain the radiation damage in GaAs particle detectors.

Rogalla, M.; Battke, M.; Duda, N.; Geppert, R.; Göppert, R.; Ludwig, J.; Irsigler, R.; Schmid, Th.; Runge, K.; Söldner-Rembold, A.

1998-02-01

290

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

SciTech Connect

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

Guo, Qinghua; /Pennsylvania U.

2005-09-14

291

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

292

The C shell, an active detector of UH nuclei. [in cosmic radiation  

NASA Technical Reports Server (NTRS)

This paper gives a brief description of the current status of the present program to develop a modular array of large electronic particle detectors. These modules were designed to study the UH nuclei in the cosmic radiation with eventual deployment on the Space Station or at a lunar base. This array would determine the abundances of elements from iron to the actinides and directly measure the energies of the lower energy nuclei. If the array was deployed on the Space Station, it would use the geomagnetic threshold to place limits on the higher energy nuclei, thus studying the energy spectrum up to about 10 GeV/n. Deployed at a lunar base, it would detect nuclei with energies down to the instrumental limit. Smaller versions could be flown on balloons to test and refine the modules.

Waddington, C. J.; Clinton, Robert R.

1990-01-01

293

A high-efficiency Transition Radiation Detector for high-counting-rate environments  

NASA Astrophysics Data System (ADS)

A prototype Transition Radiation Detector (TRD) with a new configuration was built and tested. The prototype consists of two individual multiwire proportional chambers (MWPC) that share a thin common central pad readout electrode. Measurements with a 55Fe source and e, ? and p of 1.5 GeV/ c showed a very good energy, position resolution and a better e/? discrimination compared to the standard structure with a single MWPC. No significant deterioration of the resolutions is observed up to counting rates of 2×105 particles cm-2 s-1. These results open the possibility of constructing TRDs with a high e/? discrimination and granularity even for high-counting rate experiments with a reasonable number of layers.

Petrovici, M.; Petri?, M.; Berceanu, I.; Simion, V.; Barto?, D.; C?t?nescu, V.; Herghelegiu, A.; M?gureanu, C.; Mois?, D.; Radu, A.; Klein-Bösing, M.; Wessels, J. P.; Wilk, A.; Andronic, A.; Garabatos, C.; Simon, R.; Uhlig, F.

2007-09-01

294

Toward 3D dosimetry of intensity modulated radiation therapy treatments with plastic scintillation detectors  

NASA Astrophysics Data System (ADS)

In this work, we present a novel two Dimensional Plastic Scintillation Detector (2D-PSD) array designed to measure dose distributions generated by high energy photon beams from medical linear accelerators. This study aim to demonstrate that the dose distribution in the irradiated volume is not modified by the presence of several hundred plastic scintillation detectors (PSDs). The 2D-PSD consists of 781 PSDs inserted in a plastic water slab. The dose distributions measured with the 2D-PSD were compared to calculations from a treatment planning system (Pinnacle3, Philips Medical Systems) and with measurements taken with an ionization chambers array (MatriXX Evolution, IBA Dosimetry). Furthermore, a clinical head and neck IMRT plan was delivered on the 2D-PSD. A good agreement is obtained between the measured and planned dose distributions. The results show that the 2D arrangement presented in this work is water equivalent and transparent to x-ray radiation. As a consequence, our design could be extended to multiple detection planes, opening the possibility for 3D dosimetry with PSDs.

Guillot, M.; Gingras, L.; Archambault, L.; Beddar, S.; Beaulieu, L.

2010-11-01

295

Conduction Effect of Thermal Radiation in a Metal Shield Pipe in a Cryostat for a Cryogenic Interferometric Gravitational Wave Detector  

NASA Astrophysics Data System (ADS)

A large heat load caused by thermal radiation through a metal shield pipe was observed in a cooling test of a cryostat for a prototype of a cryogenic interferometric gravitational wave detector. The heat load was approximately 1000 times larger than the value calculated by the Stefan-Boltzmann law. We studied this phenomenon by simulation and experiment and found that it was caused by the conduction of thermal radiation in a metal shield pipe.

Tomaru, Takayuki; Tokunari, Masao; Kuroda, Kazuaki; Uchiyama, Takashi; Okutomi, Akira; Ohashi, Masatake; Kirihara, Hiroyuki; Kimura, Nobuhiro; Saito, Yoshio; Sato, Nobuaki; Shintomi, Takakazu; Suzuki, Toshikazu; Haruyama, Tomiyoshi; Miyoki, Shinji; Yamamoto, Kazuhiro; Yamamoto, Akira

2008-03-01

296

X-ray radiation detectors of ``scintillator-photoreceiving device type'' for industrial digital radiography with improved spatial resolution  

NASA Astrophysics Data System (ADS)

Main types of photoreceivers used in X-ray digital radiography systems are luminescent screens that transfer the optical image onto charge collection instruments, which require cooling, and semiconductor silicon detectors, which limit the contrast sensitivity. We have developed and produced X-ray radiation detectors of "scintillator-photoreceiving device" (S-PRD) type, which are integrally located on the inverse side of the photodiode (PD). The receiving-converting circuit (RCC) is designed for data conversion into digital form and their input into PC. Software is provided for RCC control and image visualization. Main advantages of these detectors are high industrial resolution (3-5 line pairs per mm), detecting activity up to 20 ?m, controlled sensitivity, low weight and small size, imaging low (0.1-0.3 mrad) object dose in real time. In this work, main characteristics of 32-, 64- and 1024-channel detectors of S-PRD type were studied and compared for X-ray sensitivity with S-PD detectors. Images of the tested objects have been obtained. Recommendations are given on the use of different scintillation materials, depending upon the purpose of a digital radiographic system. The detectors operate in a broad energy range of ionizing radiation, hence the size of the controlled object is not limited. The system is sufficiently powerful to ensure frontal (through two walls) observation of pipelines with wall thickness up to 10 cm.

Ryzhykov, V. D.; Lysetska, O. K.; Opolonin, O. D.; Kozin, D. N.

2003-06-01

297

Radiation hard detectors from silicon enriched with both oxygen and thermal donors: improvements in donor removal and long-term stability with regard to neutron irradiation  

Microsoft Academic Search

Detectors made on the silicon wafers with high concentration of thermal donors (TD), which were introduced during the high temperature long time (HTLT) oxygenation procedure, have been investigated in the study of radiation hardness with regard to neutron irradiation and donor removal problems in irradiated high resistivity Si detectors. Two facts have been established as the evidence of radiation hardness

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

2002-01-01

298

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

299

Electrical-modelling, design and simulation of cumulative radiation effects in semiconductor pixels detectors: prospects and limits  

E-print Network

Silicon detectors have gained in popularity since silicon became a widely used micro/nanoelectronic semiconductor material. Silicon detectors are used in particle physics as well as imaging for pixel based detecting systems. Over the past twenty years a lot of experimental efforts have been focused on the effects of ionizing and non-ionizing radiation on silicon pixels. Some of this research was done in the framework of high luminosity particle physics experiments, along with radiation hardness studies of basic semiconductors devices. In its simplest form the semiconductor pixel detectors reduce to a PIN or PN structure partially or totally depleted, or in some MOS and APD (Avalanche PhotoDiode) structures. Bulk or surface defects affect considerably transport of free carriers. We propose guidelines for pixel design, which will be tested through a few pixel structures. This design method includes into the design the properties of defects. The electrical properties reduce to parameters, which can be introduced...

Fourches, Nicolas T; Chipaux, Rémi

2014-01-01

300

Development of a fast read-out system of a single photon counting detector for mammography with synchrotron radiation  

NASA Astrophysics Data System (ADS)

A single-photon counting detector read-out system for mammography with synchrotron radiation has been developed with the aim to meet the needs of the mammographic imaging station of the SYRMEP beamline at ELETTRA. The system called PICASSO (Phase Imaging for Clinical Application with Silicon detector and Synchrotron radiatiOn) is a modular detector that implements a read-out system with MYTHEN II ASICs, an embedded Linux-based controller board and a Scientific Linux acquisition workstation. The system architecture and characteristics are herein presented. The system was tested at the SYRMEP beamline and achieved a frame rate of 33 Hz for 8448 channels at 24-bit dynamic range, and it is capable of continuously acquiring up to 2000 frames. Standard mammographic phantoms were imaged and good quality images were obtained at doses comparable with what is delivered in conventional full field mammographic systems.

Lopez, F. C.; Rigon, L.; Longo, R.; Arfelli, F.; Bergamaschi, A.; Chen, R. C.; Dreossi, D.; Schmitt, B.; Vallazza, E.; Castelli, E.

2011-12-01

301

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

302

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

303

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

304

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

305

Comparison of radiation damage parameter values for the widely used semiconductor gamma detector materials in wide energy range  

NASA Astrophysics Data System (ADS)

Number of displaced atoms (NDA) values for 3 different semiconductor detector materials (Ge, Si, and GaAs) was reviewed at 26 different primary energies emitted from 9 radiation sources (241Am, 133Ba, 109Cd, 57Co, 60Co, 137Cs, 152Eu, 55Fe and 153Gd) widely used in the literature. FLUKA Monte Carlo code was used to simulate interactions between X-gamma rays and semiconductor detector materials. Germanium has the highest average NDA value in the studied three semiconductors.

Korkut, Turgay; Korkut, Hatun

2014-04-01

306

Simulation of Signals in Ultra Radiation-Hard Silicon Pixel Detectors  

Microsoft Academic Search

A detailed simulation of silicon pixel detectors irradiated to the very high fluences, in the range (1015divide1016neqcm-2) foreseen for vertex detectors after the Large Hadron Collider luminosity upgrade, is presented. The charge collection properties and the detector response were computed for different silicon materials (Standard Float Zone, Diffusion Oxygenated Float Zone, Czochralski, epitaxial silicon), operating conditions (bias voltage, temperature) and

T. Lari; C. Troncon

2006-01-01

307

A program in detector development for the US synchrotron radiation community  

Microsoft Academic Search

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

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

2001-01-01

308

Photoluminescence of Pb1-XCdXJ2 alloys --new radiation detector materials  

NASA Astrophysics Data System (ADS)

It is well known that lead iodide (PbJ2) crystals are promising materials for radiation detectors operating at room temperature. In this paper we are reporting the first study of photoluminescence (PL) spectra of 2H-Pb1-XCdxJ2 (X=0.02 -- 0.40) alloys. It was shown that for 2H-PbJ2 PL line of free excitons corresponds to E=2.497 eV. Other exciton line at E=2.492 eV is assigned to bound excitons. The most intensive PL wide structural band is near energies 2.38-243 eV which corresponds to the recombination of donor-acceptor pairs. For Pb1-XCdxJ2 crystals the exciton lines are shifted to the short-wavelength region ( for X=0.10 and X=0.30 the position of bound exciton line corresponds to 2.567 eV and 2.654 eV, respectively. It indicates about the formation semiconductor alloys. Analysis of form and energy position of PL lines shown that for X<=0.20 these alloys are homogeneous. At larger value X the formation of CdJ2 clusters in PbJ2 crystals take place. For X>=0.40 the crystals are strongly inhomogeneous.

Gnatenko, Yuriy; Beynik, Igor; Skubenko, Pavlo

2007-03-01

309

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

310

CdTexSe1-x: a potential candidate for room-temperature radiation detector applications  

NASA Astrophysics Data System (ADS)

CdTexSe1-x, with its several advantages over the conventional CdZnTe (CZT) material, offers potential as a roomtemperature radiation detector. Its main advantage is the near-unity segregation coefficient of Se in the CdTe matrix that results in higher compositional homogeneity of the grown ingot. In this paper, we discussed the growth of CdTeSe crystals by various techniques, such as the Traveling Heater method and the Vertical Bridgman technique. We analyzed the different defects in the grown ingots, including Te inclusions/precipitations, sub-grain boundaries and dislocation networks, and studied their effects on the materials' charge-transport characteristics. Our experimental findings demonstrated several advantages of CdTeSe over CZT, in addition to the near-unity segregation coefficient of Se, including lower concentrations of Te-inclusions/precipitations and sub-grain boundaries and a higher degree of uniformity. Our findings on its charge-transport characteristics also are very encouraging.

Roy, U. N.; Bolotnikov, A. E.; Camarda, G. S.; Cui, Y.; Hossain, A.; Yang, G.; Tappero, R.; James, R. B.

2014-09-01

311

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

312

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 8×1014n/cm2. The film performances were studied before and after the 14 MeV neutron irradiation by using 5.5 MeV ? from Am241 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

313

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

314

High quantum efficiency megavoltage imaging with thick scintillator detectors for image guided radiation therapy  

NASA Astrophysics Data System (ADS)

In image guided radiation therapy (IGRT), imaging devices serve as guidance systems to aid patient set-up and tumor volume localization. Traditionally, 2-D megavoltage x-ray imagers, referred to as electronic portal imaging devices (EPIDs), have been used for planar target localization, and have recently been extended to perform 3-D volumetric reconstruction via cone-beam computed tomography (CBCT). However, current EPIDs utilize thin and inefficient phosphor screen detectors and are subsequently limited by poor soft tissue visualization, which limits their use for CBCT. Therefore, the use of thick scintillation media as megavoltage x-ray detectors for greater x-ray sensitivity and enhanced image quality has recently been of significant interest. In this research, two candidates for thick scintillators: CsI(Tl) and terbium doped scintillation glass were investigated in separate imaging configurations. In the first configuration, a thick scintillation crystal (TSC) consisting of a thick, monolithic slab of CsI(Tl) was coupled to a mirror-lens-camera system. The second configuration is based on a fiber-optic scintillation glass array (FOSGA), wherein the scintillation glass is drawn into long fiber-optic conduits, inserted into a grid-type housing constructed out of polymer-tungsten alloy, and coupled to an array of photodiodes for digital read-out. The imaging prototypes were characterized using theoretical studies and imaging measurements to obtain fundamental metrics of imaging performance. Spatial resolution was measured based on a modulation transfer function (MTF), noise was evaluated in terms of a noise power spectrum (NPS), and overall contrast was characterized in the form of detective quantum efficiency (DQE). The imaging studies were used to optimize the TSC and FOSGA imagers and propose prototype configurations for order-of-magnitude improvements in overall image quality. In addition, a fast and simple technique was developed to measure the MTF, NPS, and DQE metrics for clinical EPID and CBCT systems based on a novel adaptation of a traditional line-pair resolution bar-pattern. This research provides two significant benefits to radiotherapy: the characterization of a new generation of thick scintillator based megavoltage x-ray imagers for CBCT based IGRT, and the novel adaptation of fundamental imaging metrics from imaging research to routine clinical performance monitoring.

Gopal, Arun

315

3D sensitive voxel detector of ionizing radiation based on Timepix device  

NASA Astrophysics Data System (ADS)

Position sensitive detectors are evolving towards higher segmentation geometries from 0D (single pad) over 1D (strip) to 2D (pixel) detectors. Each step has brought up substantial expansion in the field of applications. The next logical step in this evolution is to design a 3D, i.e. voxel detector. The voxel detector can be constructed from 2D volume element detectors arranged in layers forming a 3D matrix of sensitive elements — voxels. Such detectors can effectively record tracks of energetic particles. By proper analysis of these tracks it is possible to determine the type, direction and energy of the primary particle. One of the prominent applications of such device is in the localization and identification of gamma and neutron sources in the environment. It can be also used for emission and transmission radiography in many fields where standard imagers are currently utilized. The qualitative properties of current imagers such as: spatial resolution, efficiency, directional sensitivity, energy sensitivity and selectivity (background suppression) can be improved. The first prototype of a voxel detector was built using a number of Timepix devices. Timepix is hybrid semiconductor detector consisting of a segmented semiconductor sensor bump-bonded to a readout chip. Each sensor contains 256x256 square pixels of 55 ?m size. The voxel detector prototype was successfully tested to prove the concept functionality. The detector has a modular architecture with a daisy chain connection of the individual detector layers. This permits easy rearrangement due to its modularity, while keeping a single readout system for a variable number of detector layers. A limitation of this approach is the relatively large inter-layer distance (4 mm) compared to the pixel thickness (0.3 mm). Therefore the next step in the design is to decrease the space between the 2D detectors.

Soukup, P.; Jakubek, J.; Vykydal, Z.

2011-01-01

316

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

317

Using synchrotron radiation angiography with a highly sensitive detector to identify impaired peripheral perfusion in rat pulmonary emphysema  

PubMed Central

Owing to limitations in spatial resolution and sensitivity, it is difficult for conventional angiography to detect minute changes of perfusion in diffuse lung diseases, including pulmonary emphysema (PE). However, a high-gain avalanche rushing amorphous photoconductor (HARP) detector can give high sensitivity to synchrotron radiation (SR) angiography. SR angiography with a HARP detector provides high spatial resolution and sensitivity in addition to time resolution owing to its angiographic nature. The purpose of this study was to investigate whether this SR angiography with a HARP detector could evaluate altered microcirculation in PE. Two groups of rats were used: group PE and group C (control). Transvenous SR angiography with a HARP detector was performed and histopathological findings were compared. Peak density of contrast material in peripheral lung was lower in group PE than group C (p < 0.01). The slope of the linear regression line in scattering diagrams was also lower in group PE than C (p < 0.05). The correlation between the slope and extent of PE in histopathology showed significant negative correlation (p < 0.05, r = 0.61). SR angiography with a HARP detector made it possible to identify impaired microcirculation in PE by means of its high spatial resolution and sensitivity. PMID:23412496

Ito, Hiromichi; Matsushita, Shonosuke; Hyodo, Kazuyuki; Sato, Yukio; Sakakibara, Yuzuru

2013-01-01

318

Investigation of low leakage current radiation detectors on n-type 4H-SiC epitaxial layers  

NASA Astrophysics Data System (ADS)

The surface leakage current of high-resolution 4H-SiC epitaxial layer Schottky barrier detectors has been improved significantly after surface passivations of 4H-SiC epitaxial layers. Thin (nanometer range) layers of silicon dioxide (SiO2) and silicon nitride (Si3N4) were deposited on 4H-SiC epitaxial layers using plasma enhanced chemical vapor deposition (PECVD) on 20 ?m thick n-type 4H-SiC epitaxial layers followed by the fabrication of large area (~12 mm2) Schottky barrier radiation detectors. The fabricated detectors have been characterized through current-voltage (I-V), capacitance-voltage (C-V), and alpha pulse height spectroscopy measurements; the results were compared with that of detectors fabricated without surface passivations. Improved energy resolution of ~ 0.4% for 5486 keV alpha particles was observed after passivation, and it was found that the performance of these detectors were limited by the presence of macroscopic and microscopic crystal defects affecting the charge transport properties adversely. Capacitance mode deep level transient studies (DLTS) revealed the presence of a titanium impurity related shallow level defects (Ec-0.19 eV), and two deep level defects identified as Z1/2 and Ci1 located at Ec-0.62 and ~ Ec-1.40 eV respectively.

Nguyen, Khai V.; Chaudhuri, Sandeep K.; Mandal, Krishna C.

2014-09-01

319

Spectroscopic response of Cd(Zn)Te radiation detectors with a Schottky diode  

NASA Astrophysics Data System (ADS)

We investigated the spectroscopic properties of several Cd(Zn)Te detectors with a Schottky contact and simulated them via a computer code. The responses were determined of 0.5-mm-thick surface-barrier Ni/Cd(Zn)Te/Ni detectors to gamma-rays from reference sources of 241Am, 133Ba, 152Eu, 137Cs and 60Co. The best measured energy-resolution at 661.67 keV (137Cs) of these detectors under 800 V of displacement voltage was better than 1.5%. The detectors' response functions, simulated with Geant4 toolkit, agreed satisfactorily with our experimental data.

Zakharchenko, Alexandr A.; Davydov, Leonid N.; Skrypnyk, Anna I.; Rybka, Alexandr V.; Kutny, Vladimir E.; Khazhmuradov, Manap A.; Fochuk, Petro M.; Sklyarchuk, Valery M.; Bolotnikov, Aleksey E.; James, Ralph B.

2014-09-01

320

Performance of epitaxial GaAs radiation detectors grown by vapour-based chemical reaction  

NASA Astrophysics Data System (ADS)

We have characterised the radiation response of thick epitaxial GaAs layers that have been grown by water vapour-based chemical reaction, a new growth technique that has the potential to fabricate high quality thick epitaxial GaAs at low cost and with fast rates. The uniformity of these thick epitaxial layers has been assessed using room temperature photoluminescence mapping. The material shows very low EL2 concentrations and excellent whole-wafer uniformity, in contrast to conventional semi-insulating LEC or VGF grown bulk GaAs. Test detectors have been fabricated from the material and their response has been measured to alpha particle and low-energy gamma ray irradiation as a function of temperature. Pulse shape analysis of the signals produced by alpha particles show a fast and slow component, corresponding to charge transport in the depleted and under-depleted regions of the device. This indicates a shallow depletion layer due to non-intentional doping of the material from residual impurities. However, even outside the depletion region, good charge transport is observed in the material, which is consistent with long carrier lifetimes and a low EL2 concentration. CV measurements have been carried out in the temperature range +20°C to -55°C, which indicate a doping level of ND˜1×10 14 cm -3. The thickness of the depletion region was measured using CV with an applied bias of 20 V, and was found to be approximately 10 ?m at room temperature, increasing to >30 ?m at -55°C.

Sellin, P. J.; El-Abbassi, H.; Rath, S.; Bourgoin, J. C.; Sun, G. C.

2003-10-01

321

Project W-151 flexible receiver radiation detector system acceptance test plan. Revision 1  

SciTech Connect

The attached document is the Acceptance Test Plan for the portion of Project W-151 dealing with acceptance of gamma-ray detectors and associated electronics manufactured at the Idaho National Engineering Laboratory (INEL). The document provides a written basis for testing the detector system, which will take place in the 305 building (300 Area).

Troyer, G.L.

1994-12-06

322

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

NASA Astrophysics Data System (ADS)

In the IAEA-AAPM dosimetry formalism, detector measurements in general nonstandard conditions are corrected using the factor k_{{{Q}_{\\text{clin}}},{{Q}_{\\text{msr}}}}^{{{f}_{\\text{clin}}},{{f}_{\\text{msr}}}} . This factor needs to be evaluated on a case-by-case basis which is difficult to accomplish in practice. The present paper aims to provide a method that allows neglecting correction factors for small and composite IMRT fields by first determining a radiation detector’s usability in these fields. Detailed models of nine radiation detectors are built: four ionization chambers (NE2571, A12, A1SL, A14), three small field detectors (PTW31018 microLion, PTW60003 natural diamond, PTW60012 unshielded diode) and two near water-equivalent detectors (alanine, W1 scintillating fiber). Using the egs_chamber Monte Carlo code, dose response functions at 6 MV and 25 MV are sampled for each detector and their corresponding volume of water. These functions are then used with a newly derived criterion to evaluate an upper bound \\xi _{{{Q}_{\\text{ns}}},{{Q}_{\\text{msr}}}}^{{{f}_{\\text{ns}}},{{f}_{\\text{msr}}}} on the variable \\epsilon _{{{Q}_{\\text{ns}}},{{Q}_{\\text{msr}}}}^{{{f}_{\\text{ns}}},{{f}_{\\text{msr}}}} if no field collimation/modulation occurs over a given perturbation zone. The variable \\epsilon _{{{Q}_{\\text{ns}}},{{Q}_{\\text{msr}}}}^{{{f}_{\\text{ns}}},{{f}_{\\text{msr}}}} is defined as the absolute value of the relative deviation from unity of a nonstandard field quality correction factor k_{{{Q}_{\\text{ns}}},{{Q}_{\\text{msr}}}}^{{{f}_{\\text{ns}}},{{f}_{\\text{msr}}}} . Using the same criterion, perturbation zones are evaluated by finding the smallest field size allowed for correction-less dosimetry with a given tolerance \\xi _{{{Q}_{\\text{ns}}},{{Q}_{\\text{msr}}}}^{{{f}_{\\text{ns}}},{{f}_{\\text{msr}}}} . For composite fields, the sensitivity of detectors to the non-uniformity of virtual symmetric collapsed beams over regions of interest specified by the criterion is studied to estimate an upper bound \\tilde{\\xi}_{{{Q}_{\\text{ns}}},Q}^{{{f}_{\\text{ns}}},{{f}_{\\text{ref}}}} on \\epsilon _{{{Q}_{\\text{ns}}},Q}^{{{f}_{\\text{ns}}},{{f}_{\\text{ref}}}} for a given beam flatness. Finally, a newly defined perturbation function is used to minimize the perturbations of the microLion chamber through density compensation. The theoretical criterion shows good agreement with full Monte Carlo simulations of \\epsilon _{{{Q}_{\\text{ns}}},{{Q}_{\\text{msr}}}}^{{{f}_{\\text{ns}}},{{f}_{\\text{msr}}}} . Perturbation zones are shown to be sensitive to both the energy of the beam and the orientation of the detector. The density-compensated microLion shows significantly improved response in both axial and radial orientations in small and composite IMRT fields. Finally, the new Exradin W1 scintillator is shown to have \\xi _{{{Q}_{\\text{ns}}},{{Q}_{\\text{msr}}}}^{{{f}_{\\text{ns}}},{{f}_{\\text{msr}}}} values under 1% in small fields. The methods presented in this work theoretically show that correction-less dosimetry of nonstandard field can be accomplished by knowing the limit of usability of radiation detectors in these conditions. Potential applications include small field output factor measurements and absolute absorbed dose to water verification in the QA of clinical IMRT fields.

Kamio, Y.; Bouchard, H.

2014-09-01

323

Calibration of solid state nuclear track detectors at high energy ion beams for cosmic radiation measurements: HAMLET results  

NASA Astrophysics Data System (ADS)

The MATROSHKA experiments and the related HAMLET project funded by the European Commission aimed to study the dose burden of the crew working on the International Space Station (ISS). During these experiments a human phantom equipped with several thousands of radiation detectors was exposed to cosmic rays inside and outside the ISS. Besides the measurements realized in Earth orbit, the HAMLET project included also a ground-based program of calibration and intercomparison of the different detectors applied by the participating groups using high-energy ion beams. The Space Dosimetry Group of the Centre for Energy Research (formerly Atomic Energy Research Institute) participated in these experiments with passive solid state nuclear track detectors (SSNTDs). The paper presents the results of the calibration experiments performed in the years 2008-2011 at the Heavy Ion Medical Accelerator (HIMAC) of the National Institute of Radiological Sciences (NIRS), Chiba, Japan. The data obtained serve as update and improvement for the previous calibration curves which are necessary for the evaluation of the SSNTDs exposed in unknown space radiation fields.

Szabó, J.; Pálfalvi, J. K.

2012-12-01

324

Assessment of 4H-SiC epitaxial layers and high resistivity bulk crystals for radiation detectors  

NASA Astrophysics Data System (ADS)

We present results of structural, electrical, and defect characterization of 4H-SiC epitaxial layers and bulk crystals and show performance of the radiation detectors fabricated from these materials. The crystal quality was evaluated by x-ray diffraction (XRD) rocking curve measurements, electron beam induced current (EBIC) imaging, and defect delineating etching in conjunction with optical microscopy and scanning electron microscopy (SEM). Studies of the electrically active intrinsic defects and impurities were conducted using thermally stimulated current (TSC) measurements in a wide temperature range of 94 - 750K. The results are correlated with the capability of bulk crystals and epitaxial layers for the detection of ?-particles, low to high energy x-rays and gamma rays. High barrier rectifying Schottky diodes have been fabricated and tested. The epitaxial 4H-SiC radiation detectors exhibited low leakage current (< 1 nA) at ~ 200 V operating voltage up to 200 C. The soft x-ray responsivity measurements performed at the National Synchrotron Light Source (NSLS) at Brookhaven National Lab (BNL) showed significantly improved characteristics compared to commercially-available SiC UV photodiode detectors.

Mandal, Krishna C.; Muzykov, Peter G.; Chaudhuri, Sandeep K.; Terry, J. R.

2012-10-01

325

The Mars Science Laboratory (MSL) Radiation Assessment Detector (RAD) and Implications for IRAS on ExoMars  

NASA Astrophysics Data System (ADS)

The Radiation Assessment Detector (RAD) on NASA's Mars Science Laboratory mission is being built to characterize the broad-spectrum of the surface radiation environment, including galactic cosmic radiation, solar proton events, and secondary neutrons. This overarching mission goal is met by RADs science objectives 1-5: 1.)Characterize the energetic particle spectrum incident at the surface of Mars, including direct and indirect radiation created in the atmosphere and regolith. 2.)Validate Mars atmospheric transmission models and radiation transport codes. 3.)Determine the radiation Dose rate and Equivalent Dose rate for humans on the Martian surface. 4.)Determine the radiation hazard and mutagenic influences to life, past and present, at and beneath the Martian surface. 5.)Determine the chemical and isotopic effects of energetic particle radiation on the Martian surface and atmosphere. To achieve these objectives, RAD will operate autonomously to provide measurements of protons from 10 to 100 MeV and heavy ions from 30 to 200 MeV/nuc, and discriminate between the various nuclei. RAD will also provide LET measurements and time series of SEP events and discriminate between neutrons and gamma rays. A pathfinder model with flight-like properties, and, by the time of the conference, a flight and flight spare model, have been tested at BNL, PTB, iThemba, CERN/CERF, and using various radioactive sources to demonstrate the measurement capabilities required by its science objectives. We will present first calibration results and compare them with GEANT4 simulations. The neutron-gamma discrimination can be achieved in a statistical manner using a combination of different scintillators1 and will also presented. Finally, we will discuss implications for the Ionizing RAdiation Sensor (IRAS) for ESA's ExoMars mission.

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

326

Novel Surface Preparation and Contacts for CdZnTe Nuclear Radiation Detectors Using Patterned Films of Semiconductors and Insulators  

NASA Astrophysics Data System (ADS)

The semiconductor Cadmium Zinc Telluride (CZT) has emerged as the material of choice for room temperature detection of X-rays and gamma-rays. The detectors will cover the energy range from 30 keV to several MeV, and will achieve excellent 662 keV energy resolution. The development of high resolution gamma ray detectors based on CZT is dependent on low electronic noise levels. One common source of noise is the surface leakage current, which limits the performance of advanced readout schemes such as the coplanar grid and pixelated architectures with steering grids. Excessive bulk leakage current can result from one of several surface effects: leaky native oxides, unsatisfied bonds, and surface damage. We propose to fabricate and test oriented [111] CZT crystals with thicknesses up to 1.5 cm with an innovative detection technique based on co-planar or other electron only transport designs using plasma processing, thin film sputtering, chemical passivation and wet etching techniques. Compared to conventional pixel detectors, the proposed contact configuration needs lower power consumption and a lower cost. The detector design can be used for building very low-cost handheld radiation detection devices.

Burger, Arnold; Groza, Michael; Conway, Adam; Payne, Steve

2013-04-01

327

Ultrafast two-dimensional electron gas detector and mixer for terahertz radiation  

NASA Astrophysics Data System (ADS)

A hot-electron bolometric detector and mixer (heterodyne detector), which uses the nonlinearities of the heated two-dimensional electron gas medium, is proposed and analyzed. The cooling process of the detector is through diffusion of the electrons into the contacts; a time constant of 1 ps and responsivity of 3000 V/W are calculated for a device which is 0.8 ?m long. The predicted double-sideband receiver noise temperature for the mixer version is in the range 1000-2000 K at 1 THz, with a 100 GHz intermediate frequency bandwidth. The operating temperature would be 77 K and the local oscillator power 1 ?W.

Yngvesson, K. S.

2000-02-01

328

Characterisation of a radiation hard front-end chip for the vertex detector of the LHCb experiment at CERN  

NASA Astrophysics Data System (ADS)

The Beetle is a 128 channel analog pipelined readout chip which is intended for use in the silicon vertex locator (VELO) of the LHCb experiment at CERN. The Beetle chip is specially designed to withstand high radiation doses. Two Beetle1.1 chips bonded to a silicon strip detector have been tested with minimum ionizing particles. The main goal was to measure the signal-to-noise (S/N) ratio of the Beetle1.1 connected to a prototype VELO detector. Furthermore we investigated the general behaviour of the Beetle1.1. In this note we present the chip architecture, the measured (S/N) numbers as well as some characteristics (e.g. risetime, spillover) of the Beetle1.1 chip. Results from a total ionizing dose irradiation test are reported.

van Bakel, N.; Baumeister, D.; van Beuzekom, M.; Bulten, H. J.; Feuerstack-Raible, M.; Jans, E.; Ketel, T.; Klous, S.; Löchner, S.; Sexauer, E.; Smale, N.; Snoek, H.; Trunk, U.; Verkooijen, H.

2003-08-01

329

Investigation of Charge Transport Properties of CdZnTe Detectors with Synchrotron X-ray Radiation  

SciTech Connect

Various internal defects, such as Te inclusions, twin boundaries, dislocation, etc., are prevalent in as-grown CdZnTe (CZT) crystals, which affect the charge transport properties of CZT crystals and, therefore, worsen the performance of CZT detectors. In order to develop high quality CZT detectors, it is imperative to clarify the effects of internal defects on the charge transport properties of CZT. Simple flood illumination with nuclear radiation source cannot reveal the nature of highly localized defects in CZT. Therefore, at Brookhaven's National Synchrotron Light Source (NSLS), we have developed a unique testing system for micro-scale defect investigation of CZT, which employs an X-ray beam collimated with the spatial resolution as small as 3 x 3 {micro}m{sup 2}, a microscopic size comparable to the scale of common defects in CZT. This powerful tool enables us to investigate the effect of internal defects on charge transport properties of CZT in detail.

Yang,G.; Bolotnikov, A.E.; Camarda, G.S.; Cui, Y.; Hossain, A.; James, R.B.

2008-10-19

330

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

PubMed

In the IAEA-AAPM dosimetry formalism, detector measurements in general nonstandard conditions are corrected using the factor k(f(clin),f(msr))(Q(clin),Q(msr)). This factor needs to be evaluated on a case-by-case basis which is difficult to accomplish in practice. The present paper aims to provide a method that allows neglecting correction factors for small and composite IMRT fields by first determining a radiation detector's usability in these fields. Detailed models of nine radiation detectors are built: four ionization chambers (NE2571, A12, A1SL, A14), three small field detectors (PTW31018 microLion, PTW60003 natural diamond, PTW60012 unshielded diode) and two near water-equivalent detectors (alanine, W1 scintillating fiber). Using the egs_chamber Monte Carlo code, dose response functions at 6 MV and 25 MV are sampled for each detector and their corresponding volume of water. These functions are then used with a newly derived criterion to evaluate an upper bound ?(f(ns),f(msr))(Q(ns),Q(msr)) on the variable ?(f(ns),f(msr))(Q(ns),Q(msr)) if no field collimation/modulation occurs over a given perturbation zone. The variable ?(f(ns),f(msr))(Q(ns),Q(msr)) is defined as the absolute value of the relative deviation from unity of a nonstandard field quality correction factor k(f(ns),f(msr))(Q(ns),Q(msr)). Using the same criterion, perturbation zones are evaluated by finding the smallest field size allowed for correction-less dosimetry with a given tolerance ?(f(ns),f(msr))(Q(ns),Q(msr)). For composite fields, the sensitivity of detectors to the non-uniformity of virtual symmetric collapsed beams over regions of interest specified by the criterion is studied to estimate an upper bound ? ?(f(ns),f(ref))(Q(ns),Q) on ?(f(ns),f(ref))(Q(ns),Q) for a given beam flatness. Finally, a newly defined perturbation function is used to minimize the perturbations of the microLion chamber through density compensation. The theoretical criterion shows good agreement with full Monte Carlo simulations of ?(f(ns),f(msr))(Q(ns) Q(msr)). Perturbation zones are shown to be sensitive to both the energy of the beam and the orientation of the detector. The density-compensated microLion shows significantly improved response in both axial and radial orientations in small and composite IMRT fields. Finally, the new Exradin W1 scintillator is shown to have ?(f(ns),f(msr))(Q(ns),Q(msr)) values under 1% in small fields. The methods presented in this work theoretically show that correction-less dosimetry of nonstandard field can be accomplished by knowing the limit of usability of radiation detectors in these conditions. Potential applications include small field output factor measurements and absolute absorbed dose to water verification in the QA of clinical IMRT fields. PMID:25118890

Kamio, Y; Bouchard, H

2014-09-01

331

Cross-calibration of the Transition Radiation Detector of AMS-02 for an Energy Measurement of Cosmic-Ray Ions  

E-print Network

Since May 2011 the AMS-02 experiment is installed on the International Space Station and is observing cosmic radiation. It consists of several state-of-the-art sub-detectors, which redundantly measure charge and energy of traversing particles. Due to the long exposure time of AMS-02 of many years the measurement of momentum for protons and ions is limited systematically by the spatial resolution and magnetic field strength of the silicon tracker. The maximum detectable rigidity for protons is about 1.8~TV, for helium about 3.6~TV. We investigate the possibility to extend the range of the energy measurement for heavy nuclei ($Z\\geq2$) with the transition radiation detector (TRD). The response function of the TRD shows a steep increase in signal from the level of ionization at a Lorentz factor $\\gamma$ of about 500 to $\\gamma\\approx20000$, where the transition radiation signal saturates. For heavy ions the signal fluctuations in the TRD are sufficiently small to allow an energy measurement with the TRD beyond t...

Obermeier, Andreas

2014-01-01

332

Gamma radiation induced background determination for (n,?) measurements with 4? detectors.  

SciTech Connect

The main focus of this report is to investigate possibilities to disentangle the target originating ?- background from background caused by scattered neutrons at the sample assuming a DANCE like detector to measure detect the capture events.

Reifarth, R.; Browne, J. C.; Esch, E. I.; Haight, R. C.; O'Donnell, J. M.; Kronenberg, A.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M.

2003-07-29

333

Application of MSM InP detectors to the measurement of pulsed X-ray radiation  

Microsoft Academic Search

Metal-semiconductor-metal (MSM) InP detectors were fabricated from base materials obtained from various manufacturers. The detectors are of interest for measurement of short X-ray pulses from laser plasma and other X-ray pulsed sources. It is because they can be made to operate up to the picosecond range and can be used for measurement of considerably hard (up to 100 keV) X-rays

L. Ryc; L. Dobrzanski; F. Dubecký; J. Kaczmarczyk; M. Pfeifer; F. Riesz; W. Slysz; B. Surma

2008-01-01

334

Correlation between quality of CZT crystals and spectrometric performance of hemispherical radiation detectors  

Microsoft Academic Search

The work presents analysis of the correlation existing between the spectrometric performance of commercially produced hemispherical detectors of volume 500 mm3 and the quality of starting CdZnTe material. More then 100 detectors made from CdZnTe crystals grown by eV Products, Saint-Gobain and Vinnel Tech. were studied. For the incoming inspection of the material an infrared (IR) transmission microscope was used.

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

2004-01-01

335

Characterisation of vertical gradient freeze semi-insulating InP for use as a nuclear radiation detector  

NASA Astrophysics Data System (ADS)

The performance of a nuclear radiation detector fabricated from Vertical Gradient Freeze (VGF) semi-insulating Fe-doped InP was investigated. Pulse height spectra were acquired when the detector was irradiated with alpha particles from 241Am, as a function of temperature and detector bias voltage. The spectroscopic performance of the detector was limited at room temperature due to the presence of a high leakage current. At a bias of -150 V, a room temperature leakage current density of 2.4×10 -6 A/mm 2 was observed which reduced to 7.1×10 -8 A/mm 2 at a temperature of -21°C. By biasing the irradiated detector contact at either a negative or positive potential, the charge collection efficiency (CCE) was measured separately for pulses produced predominantly by electron transport and for pulses produced predominantly by hole transport, respectively. At -21°C a maximum CCE of 72% was obtained for the electron signal and 44% for the hole signal. As a function of bias the CCE of the electrons remained constant in the temperature range -21°C to +19°C, whilst that of the holes exhibited a significant variation. By comparison with the Hecht relationship estimates of the carrier mobility-lifetime ( ??) products are deduced, which are similar for both holes and electrons and in the range 5×10 -7-8×10 -7 cm 2/V. A reduction in ?? is observed at lower temperature for holes, whereas the value for electrons remains constant over the temperature range studied.

El-Abbassi, H.; Rath, S.; Sellin, P. J.

2001-06-01

336

The ICARE-NG detectors' family: a new set of data for Earth's radiation belt characterization  

NASA Astrophysics Data System (ADS)

10 years ago, CNES and ONERA have developed a new low mass and low power solid state detector named ICARE-NG. This monitor is currently flying in the frame of CARMEN-1 & 2 missions respectively on SAC-D and JASON-2 satellites. The next mission, CARMEN-3, corresponds to the same instrument planned to be mounted onboard the upcoming JASON-3 satellite. Different papers have already highlighted the quality of the measurements obtained thanks to the high energy resolution of the instrument, for both electrons and protons. This talk aims at reviewing the benefits of such a detector (much simpler than a scientific one) providing multi-spacecraft measurements in Low Earth Orbit (LEO). In particular, these monitors are a rare opportunity to observe both long term variations in LEO and gradients between orbits. Finally, we will present data comparison and highlights from these detectors during recent magnetic storms.

Boscher, Daniel; Lazaro, Didier; Maget, Vincent; Rolland, Guy; Lorfevre, Eric; Ecoffet, Robert

337

Laser-processed three dimensional graphitic electrodes for diamond radiation detectors  

NASA Astrophysics Data System (ADS)

We have used an original approach for diamond detectors where three dimensional buried graphitic electrodes are processed in the bulk of a diamond substrate via laser-induced graphitization. Prototype made of polycrystalline chemical vapor deposition diamond was fabricated using a nanosecond UV laser. Its charge collection efficiency was evaluated using ?-particles emitted by a 241-Americium source. An improved charge collection efficiency was measured proving that laser micro-machining of diamond is a valid option for the future fabrication of three dimensional diamond detectors.

Caylar, Benoît; Pomorski, Michal; Bergonzo, Philippe

2013-07-01

338

A new detector for sub-millisecond EXAFS spectroscopy at the European Synchrotron Radiation Facility.  

PubMed

A new FReLoN (Fast-Readout Low-Noise) high-frame-rate detector adopted for the fast continuous collection of X-ray absorption spectra is presented. The detector is installed on the energy-dispersive X-ray absorption beamline ID24 at the ESRF and is capable of full time-resolved EXAFS spectra collection with over 4?kHz repetition rate and 0.2?ms exposure time. An example of the in situ kinetic study of the high-temperature oxidation of metallic iron is presented. PMID:25343790

Kantor, Innokenty; Labiche, Jean Claude; Collet, Emmanuel; Siron, Laurent; Thevenin, Jean Jacques; Ponchut, Cyril; Borrel, Jacques; Mairs, Trevor; Marini, Carlo; Strohm, Cornelius; Mathon, Olivier; Pascarelli, Sakura

2014-11-01

339

Nanostructured LaF{sub 3}:Ce Quantum Dot Nuclear Radiation Detector  

SciTech Connect

Many radioactive isotopes have low energy X-rays and high energy gamma rays of interest for detection. The goal of the work presented was to demonstrate the possibility of measuring both low-energy X-rays and relatively high-energy gamma rays simultaneously using the nano-structured lanthanum bromide, lanthanum fluoride, or cerium bromide. The key accomplishments of the project was the building and acquisition of the LaF3:Ce nanocomposite detectors. Nanocomposite detectors are sensitive to {gamma}’s as well as n’s and X-rays.

Guss, P., Guise, R., Reed, M., Mukhopadhyay, S., Yuan, D.

2010-11-01

340

Effect of electron transport properties on unipolar CdZnTe radiation detectors: LUND, SpectrumPlus, and Coplanar Grid  

SciTech Connect

Device simulations of (1) the laterally-contacted-unipolar-nuclear detector (LUND), (2) the SpectrumPlus, (3) and the coplanar grid made of Cd{sub 0.9}Zn{sub 0.1}Te (CZT) were performed for {sup 137}Cs irradiation by 662.15 keV gamma-rays. Realistic and controlled simulations of the gamma-ray interactions with the CZT material were done using the MCNP4B2 Monte Carlo program, and the detector responses were simulated using the Sandia three-dimensional multielectrode simulation program (SandTMSP). The simulations were done for the best and the worst expected carrier nobilities and lifetimes of currently commercially available CZT materials for radiation detector applications. For the simulated unipolar devices, the active device volumes were relatively large and the energy resolutions were fairly good, but these performance characteristics were found to be very sensitive to the materials properties. The internal electric fields, the weighting potentials, and the charge induced efficiency maps were calculated to give insights into the operation of these devices.

Ralph B. James

2000-01-07

341

Design and optimization of large area thin-film CdTe detector for radiation therapy imaging applications  

SciTech Connect

Purpose: The authors investigate performance of thin-film cadmium telluride (CdTe) in detecting high-energy (6 MV) x rays. The utilization of this material has become technologically feasible only in recent years due to significant development in large area photovoltaic applications. Methods: The CdTe film is combined with a metal plate, facilitating conversion of incoming photons into secondary electrons. The system modeling is based on the Monte Carlo simulations performed to determine the optimized CdTe layer thickness in combination with various converter materials. Results: The authors establish a range of optimal parameters producing the highest DQE due to energy absorption, as well as signal and noise spatial spreading. The authors also analyze the influence of the patient scatter on image formation for a set of detector configurations. The results of absorbed energy simulation are used in device operation modeling to predict the detector output signal. Finally, the authors verify modeling results experimentally for the lowest considered device thickness. Conclusions: The proposed CdTe-based large area thin-film detector has a potential of becoming an efficient low-cost electronic portal imaging device for radiation therapy applications.

Parsai, E. Ishmael; Shvydka, Diana; Kang, Jun [Department of Radiation Oncology, University of Toledo Health Sciences Campus, 3000 Arlington Avenue, Toledo, Ohio 43614 (United States); Department of Radiation Oncology, John Hopkins University, 401 N Broadway, Suite 1440, Baltimore, Maryland 21231 (United States)

2010-08-15

342

Resonant nuclear scattering of synchrotron radiation: Detector development and specular scattering from a thin layer of {sup 57}Fe  

SciTech Connect

This thesis explores resonant nudear scattering of synchrotron radiation. An introductory chapter describes some useful concepts, such as speedup and coherent enhancement, in the context of some basic physical principles. Methods of producing highly monochromatic synchrotron beams usmg either electronic or nuclear scattering are also discussed. The body of the thesis concentrates on detector development and specular scattering from iynthetic layered materials. A detector employing n-dcrochannel plate electron multipliers is shown to have good ({approximately}50%) effidency for detecting 14.4 key x-rays incident at small ({approximately}0.5 degree) grazing angles onto Au or CsI photocathodes. However, being complicated to use, it was replaced with a large area (>=lan2) avalanche photodiode (APD) detector. The APD`s are simpler to use and have comparable (30--70%) efficiencies at 14.4 key, subnanosecond time resolution, large dynan-dc range (usable at rates up to {approximately}10{sup 8} photons/second) and low (<{approximately}0.01 cts/sec) background rates. Maxwell`s equations are used to derive the specular x-ray reflectivity of layered materials with resonant transitions and complex polarization dependencies. The effects of interfadal roughness are treated with some care, and the distorted wave Born approximation (DWBA) used to describe electronic scattering is generalized to the nuclear case. The implications of the theory are discussed in the context of grazing incidence measurements with emphasis on the kinematic and dynamical aspects of the scattering.

Baron, A.Q.R.

1995-04-01

343

Structural and Electronic Properties of Gold Contacts on CdZnTe with Different Surface Finishes for Radiation Detector Applications  

NASA Astrophysics Data System (ADS)

State-of-the-art room-temperature, high-resolution x-ray and gamma-ray semiconductor detectors can be fabricated from CdZnTe (CZT) crystals. The structural and electronic properties of the CZT surface, especially the contact interfaces, can have a substantial effect on radiation detector performance, for example leakage current, signal-to-noise ratio, and energy resolution, especially for soft x-rays and large pixilated arrays. Atomically smooth and defect-free surfaces are desirable for high-performance CZT-based detectors; chemo-mechanical polishing (CMP) is typically performed to produce such surfaces. The electrical behavior of the metal/CZT interface varies substantially with surface preparation before contact deposition, and with choice of metal and deposition technique. We report a systematic study of the structural and electronic properties of gold (Au) contacts on CZT prepared with different surface finishes. We observed subsurface damage under Au contacts on CMP-finished CZT and abrupt interfaces for Au on chemically-polished (CP) CZT. Schottky barrier formation was observed for Au contacts, irrespective of surface finish, and less charge trapping and low surface resistance were observed for CP-finished surfaces. Pre-deposition surface treatment produced interfaces free from oxide layers.

Tari, S.; Aqariden, F.; Chang, Y.; Ciani, A.; Grein, C.; Li, Jin; Kioussis, N.

2014-08-01

344

Assessment of radiation exposure outside the radiotherapeutic room during medical accelerator beam emission with the use of TL detectors (radiation exposure outside a LINAC room).  

PubMed

Photon and neutron soft tissue absorbed doses near the entrance door to the medical LINAC treatment room were measured with the use of thermoluminescent detectors LiF:Mg,Cu,P in the anthropomorphic phantom. Two different therapeutic beams (6 and 15 MV) and four treatment techniques were involved in the present study. This allowed one to investigate the contribution of scattered X rays, secondary neutrons and gamma rays to the radiation field. Photon absorbed dose rates 50 cm away from the LINAC room door during emission of 15-MV X rays varied between 4.1×10(-4) and 5.6×10(-4) Gy h(-1), depending on the gantry position and the irradiation field size, whereas in the case of 6-MV therapeutic irradiation these doses are ?1.5 times lower. In the case of 15-MV beam emission, a mixed radiation field near the bunker door is observed with the photon radiation as the main component, which includes a 33.1 % contribution of the induced gamma radioactivity and ?2.1 % contribution of the neutron radiation. PMID:23554424

Polaczek-Grelik, Kinga; Koz?owska, Beata; Dybek, Marcin; Obryk, Barbara; Ciba, Aleksander

2013-09-01

345

Preliminary studies and tests of semiconductors for their use as nuclear radiation detectors  

E-print Network

circuits that may be used to make preliminary tests on the use of' junction semiconductor de- vices as primary instruments for detecting nuclear radiation. A junction semiconductor device is used to control the flow of electrons in an electronic circuit.... This thesis is limited to the study of the pulses formed in a semiconductor junction~ under reverse bias conditions, due to incident nuclear radiation and background thermal radiations A semiconductor junction is the area or vicinity of contact between...

Willis, Giles Whitehurst

2012-06-07

346

This work centers around a state of the art gamma and neutron radiation detector, which is able to display radiation information about its surrounding at every second. Information about the count  

E-print Network

ABSTRACT This work centers around a state of the art gamma and neutron radiation detector, which the count level is displayed along with the energy range of the detected radiation. Currently, similar, allowing workers to stay at a safe distance. The sensor has been characterized using exempt Cs-137 and Co

Abidi, Mongi A.

347

Transactions ACA: Volume 34 (1999) 11-25. SYNCHROTRON RADIATION AND DETECTORS: SYNERGISTS IN A DANCE  

E-print Network

IN A DANCE Sol M. Gruner Physics Department and CHESS Cornell University Ithaca, NY 14853-2501 Growth UNIVERSITY CCD detectors have their genesis in techniques of image intensification and the TV-type detection on photographic film. Although the resulting pictures appear crude by modern standards, George was encouraged

Gruner, Sol M.

348

Voltage-tunable detectors for Terahertz radiation operating above 100k with ns rise times  

Microsoft Academic Search

Collective vibrations of proteins, rotations of small molecules, excitations of high-temperature superconductors, and electronic transitions in semiconductor nanostructures occur with characteristic frequencies between 1 and 10 THz [1]. Applications to medicine, communications, security and other fields are emerging. However, mapping the coldest parts of the universe has been the largest driver for developing THz detectors [2]. The result is a

G. B. Serapiglia

2005-01-01

349

Performance of a silicon microstrip detector in a high radiation environment  

SciTech Connect

The performance of a silicon microstrip detector has been studied in a high rate environment using electron, pion, and proton beams. The pulse height, time response, and leakage current have been studied as a function of particle fluence up to a total integrated flux of about 4 {times} 10{sup 14} protons/cm{sup 2}. 3 figs.

Mishra, C.S.; Brown, C.N. (Fermi National Accelerator Lab., Batavia, IL (USA)); Kapustinsky, J.; Leitch, M.J.; McGaughey, P.L.; Peng, J.C.; Sailor, W.; Holzscheiter, K. (Los Alamos National Lab., NM (USA)); Sadler, M. (Abilene Christian Univ., TX (USA))

1990-05-01

350

Radiation hardness studies of CdTe and HgI2 for the SIXS particle detector on-board the BepiColombo spacecraft  

NASA Astrophysics Data System (ADS)

We report of the radiation hardness measurements that were performed in the developing work of a particle detector on-board ESA's forthcoming BepiColombo spacecraft. Two different high- Z semiconductor compounds, cadmium telluride (CdTe) and mercuric iodide (HgI 2), were irradiated with 22 MeV protons in four steps to attain the estimated total dose of 1012 p/cm2 for the mission time. The performance of the detectors was studied before and after every irradiation with radioactive 55Fe source Mn K ? 5.9 keV emission line. We studied the impact of the proton beam exposure on detector leakage current, energy resolution and charge collection efficiency (CCE). Also the reconstructive effect of annealing on radiation induced damage was tested for CdTe detector.

Ahoranta, J.; Uunila, M.; Huovelin, J.; Andersson, H.; Vainio, R.; Virtanen, A.; Kettunen, H.

2009-07-01

351

A study for reduction of radiation pressure noise in gravitational wave detectors  

Microsoft Academic Search

We describe an experimental conceptual design for observation and reduction of radiation pressure noise. The radiation pressure noise is increased in a high finesse cavity with a small mass mirror. In our experiment a Fabry-Perot Michelson interferometer with a homodyne detection scheme will be built with Fabry-Perot cavities of finesse of 10000 containing suspended mirrors of 23 mg. To observe

S. Sakata; V. Leonhardt; S. Kawamura; K. Numata; O. Miyakawa; S. Sato; A. Nishizawa; T. Yamazaki; M. Fukushima; A. Furusawa; A. Sugamoto

2008-01-01

352

Characterisation of SiC photo-detectors for solar UV radiation monitoring  

NASA Astrophysics Data System (ADS)

Silicon carbide has a potential for solar UV radiation monitoring: extremely resistant to UV radiation damage, nearly-blind to visible and infrared radiation and less sensitive to temperature variations than standard radiometric systems. A radiometer composed by three SiC photodiodes has been designed, manufactured and tested under solar radiation. Two photodiodes are equipped with filters in the UVB (280-315 nm) and UVA (315-400 nm) ranges while a third is filtered to match the erythemal action spectrum. UVA, UVB components of the solar radiation as well as UV index (UVI) at the earth's surface have been determined in two site positions in Tuscany, Italy. Data as a function of day-light allowed us to evaluate total optical thickness for UVA and UVB: ?UVA=0.46 and ?UVB=1.8. UVI values measured during the year well compares with computed ones used for weather forecast procedures.

Borchi, E.; Macii, R.; Bruzzi, M.; Scaringella, M.

2011-12-01

353

Radiative thermal noise for transmissive optics in gravitational-wave detectors  

NASA Astrophysics Data System (ADS)

Radiative losses have traditionally been neglected in the calculation of thermal noise of transmissive optical elements because for the most commonly used geometries they are small compared to losses due to thermal conduction. We explore the use of such transmissive optical elements in extremely noise-sensitive environments such as the arm cavities of future gravitational-wave interferometers. This drives us to a geometry regime where radiative losses are no longer negligible. In this paper we derive the thermorefractive noise associated with such radiative losses and compare it to other known sources of thermal noise.

Dwyer, Sheila; Ballmer, Stefan W.

2014-08-01

354

Radiative Thermal Noise for Transmissive Optics in Gravitational-Wave Detectors  

E-print Network

Radiative losses have traditionally been neglected in the calculation of thermal noise of transmissive optical elements because for the most commonly used geometries they are small compared to losses due to thermal conduction. We explore the use of such transmissive optical elements in extremely noise-sensitive environments such as the arm cavities of future gravitational-wave interferometers. This drives us to a geometry regime where radiative losses are no longer negligible. In this paper we derive the thermo-refractive noise associated with such radiative losses and compare it to other known sources of thermal noise.

Sheila Dwyer; Stefan W. Ballmer

2014-07-21

355

Transient and steady-state dark current mechanisms in amorphous selenium avalanche radiation detectors  

SciTech Connect

A theoretical model for describing bias-dependent transient and steady-state behaviors of dark current in amorphous selenium (a-Se) avalanche detector structures has been developed. The analytical model considers bulk thermal generation current from mid-gap sates, transient carrier depletion, and carrier injection from the electrodes incorporating avalanche multiplication. The proposed physics-based dark current model is compared with the published experimental results on three potential a-Se avalanche detector structures. The steady-state dark current is the minimum for the structures that have effective blocking layers for both holes and electrons. The transient decay time to reach a plateau decreases considerably with increasing electric field.

Kabir, M. Z.; Imam, Safayat-Al [Department of Electrical and Computer Engineering, Concordia University, 1455 Blvd. de Maisonneuve West, Montreal, Quebec H3G 1M8 (Canada)] [Department of Electrical and Computer Engineering, Concordia University, 1455 Blvd. de Maisonneuve West, Montreal, Quebec H3G 1M8 (Canada)

2013-04-15

356

Fast-neutron radiation resistance of silicon surface-barrier detectors  

Microsoft Academic Search

Jtectors were made from BKEF-200 n-type silicon with a specific resistance of 200 ~\\/em. The maximum neutron flux incident on the detectos was 4- 1013 neutrons\\/cm 3. Five detectors were irradiated with a flux density of 2.2 ?9 108 neutrons\\/cm ~ ?9 see, and ten with a flux density of 5.5 ?9 108 neutrons\\/cm 2 ?9 see, with five of

I. I. Lazutkin; B. I. Sinitsyn; O. P. Fedoseeva; S. G. Tsypin

1972-01-01

357

Charged-particle induced radiation damage of a HPGe gamma-ray detector during spaceflight  

Microsoft Academic Search

The Mars Observer spacecraft was launched on September 26, 1992 with a planned arrival at Mars after an 11-month cruise. Among the scientific instruments carried on the spacecraft was a Gamma-Ray Spectrometer (GRS) experiment to measure the composition of Mars. The GRS used a passively cooled high-purity germanium detector for measurements in the 0.2–10MeV region. The sensor was a closed-end

Larry G Evans; Richard Starr; Johannes Brückner; William V Boynton; S. H Bailey; J. I. Trombka

1999-01-01

358

Radiation-Hardened Gallium Nitride Detector and Arrays for Fusion Diagnostics  

SciTech Connect

This poster reports testing to confirm that GaN devices exhibit the extreme radiation hardness needed for use at the NIF, functioning properly after 1x10{sup 12} protons/cm{sup 2} proton irradiation in one year.

Sun, K. X., and MacNeil, L.

2011-09-08

359

Calibrating an optical scanner for quality assurance of large area radiation detectors  

NASA Astrophysics Data System (ADS)

A gas electron multiplier (GEM) is a particle detector used in high-energy physics. Its main component is a thin copper-polymer-copper sandwich that carries Ø =70? ± ?5?µm holes. Quality assurance (QA) is needed to guarantee both long operating life and reading fidelity of the GEM. Absence of layer defects and conformity of the holes to specifications is important. Both hole size and shape influence the detector’s gas multiplication factor and hence affect the collected data. For the scanner the required lateral measurement tolerance is ± 5?µm. We calibrated a high aspect ratio optical scanning system (OSS) to allow ensuring the quality of large GEM foils. For the calibration we microfabricated transfer standards, which were imaged with the OSS and which were compared to corresponding scanning electron microscopy (SEM) images. The calibration fulfilled the ISO/IEC 17025 and UKAS M3003 requirements: the calibration factor was 1.01? ± ?0.01, determined at 95% confidence level across a 950? × ?950?mm2 area. The proposed large-scale scanning technique can potentially be valuable in other microfabricated products too.

Karadzhinova, A.; Hildén, T.; Berdova, M.; Lauhakangas, R.; Heino, J.; Tuominen, E.; Franssila, S.; Hæggström, E.; Kassamakov, I.

2014-11-01

360

Radiation tolerance studies using fault injection on the Readout Control FPGA design of the ALICE TPC detector  

NASA Astrophysics Data System (ADS)

Single Event Upsets (SEUs) are a major concern for the TPC Readout Control Unit (RCU) of the ALICE experiment. A SEU is defined as a radiation related bit-flip in a memory cell, and a SEU in the onboard SRAM based FPGA of the RCU may lead to corrupted data or, even worse, a system malfunction. The latter situation will affect the operation of the ALICE detector since it causes a premature end of data taking. Active partial reconfiguration is utilized in a dedicated reconfiguration solution on the RCU, and this makes it possible to implement fault injection. Fault injection means inserting bit flips in the configuration memory of the FPGA in a controlled laboratory environment. This paper presents the results of the fault injection study and shows how this result can be combined with SEU measurements to estimate the functional failure rate as a function of luminosity.

Alme, J.; Fehlker, D.; Lippmann, C.; Mager, M.; Rehman, A. U.; Røed, K.; Röhrich, D.; Ullaland, K.

2013-01-01

361

X-RAY PHOTOEMISSION ANALYSIS OF PASSIVATED Cd(1-x)ZnxTe SURFACES FOR IMPROVED RADIATION DETECTORS  

SciTech Connect

Surface passivation of device-grade CdZnTe was investigated using x-ray photoelectron spectroscopy in combination with transport property measurements after Br-MeOH (2% Br) and KOH/NH{sub 4}F/H{sub 2}O{sub 2} solutions were used to etch and oxidize the surface. 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 radiation detector devices.

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

2008-05-12

362

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

NASA Astrophysics Data System (ADS)

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

Merlo, Jean-Pierre

2014-06-01

363

An investigation of the use of semiconductors as detectors of nuclear radiation  

E-print Network

IV. DESIRED CHARACTERISTICS OF A SEMICONDUCTOR DETECTOR. A. Dimensions of Depletion Region. . . B. Resistivity of the Material Used. . . C. Depth of Junction. D. Biasing E. Case of Construction F . Leakage Current G. Junction Area H. Summary..., capacitance = C = dv (3. 16) Therefore, using Equation (3. 16), the capacitance per unit area of the depletion region on the n-region side of the junction, C, is given by n' I/2 C = ? [2N KqV] tn N C, q (2N CqV ) d d tn Substituting Equation (3 . 12...

Ivy, Edward Weber

2012-06-07

364

Charge collection in semi-insulator radiation detectors in the presence of a linear decreasing electric field  

NASA Astrophysics Data System (ADS)

In 1932 Hecht obtained his famous equation concerning the charge induced on the plates of a planar radiation detector in the presence of a uniform electric field. It is well known that in many cases, due to non-ohmic contacts or, in any case, in the presence of spatial charge, the internal electric field is no longer constant, so this formula could lead to wrong conclusions. In this article the authors examine the common case of an electric field decreasing linearly along the detector thickness. This is a very interesting case because this shape of field is fairly widespread in the presence of diffused spatial charge and the functional dependence of the collected charge on varying the applied bias, in some cases, is similar to the Hecht equation. The authors believe that this model could be an important instrument for interpreting the data arising from pulsed photocurrent measures. Starting from Ramo-Shockley theorem and under the same Hecht's hypotheses (except for the uniform field), we calculate the new relation between the collected charge and the applied bias.

Zanichelli, M.; Santi, A.; Pavesi, M.; Zappettini, A.

2013-09-01

365

Development and Testing of Gallium Arsenide Photoconductive Detectors for Ultra Fast, High Dose Rate Pulsed Electron and Bremsstrahlung Radiation Measurements  

SciTech Connect

Real time radiation dose measurements are challenging in high dose rate environments such as those used for testing electronic devices or biological agents. Dosimetry needs in pulsed reactor fields and particle accelerator facilities require development of dosimeters with fast (10 s of picoseconds) response to pulsed radiation, linear response over a wide range of dose rates (up to 10{sup 11} Gy/s), high resistance to radiation damage, and successful operation in mixed gamma and neutron environments. Gallium arsenide photoconductive detectors (GaAs PCD) have been shown to exhibit many of these desirable characteristics, especially fast time response. Less than 50 ps time resolution has been demonstrated when previously irradiated by fission neutrons. We have conducted a study of the response-time dependence on neutron fluence, starting with fluences at {approx}10{sup 14} n/cm{sup 2}. A 23-MeV electron beam was used to produce photoneutrons in a tungsten target for irradiation of a GaAs wafer from which PCDs were made. The process was modeled using MCNPX computer code and the simulation results were compared to the experimental measurements. GaAs PCDs were fabricated from both neutron-irradiated and non-irradiated GaAs samples. The results of the preliminary tests of these devices in accelerator-produced pulses of electron and bremsstrahlung radiation of various energies (13 to 35 MeV) and pulse lengths (100 ps to 4 {mu}s) are presented together with an overview of the future plans of continuing GaAs PCD research at Idaho State University.

Kharashvili, George; Makarashvili, Vakhtang; Mitchell, Marc; Beezhold, Wendland; Spaulding, Randy; Wells, Douglas; Gesell, Thomas [Department of Physics, Idaho State University, Campus box 8106, Pocatello, Idaho 83209 (United States); Wingert, Wayne [Department of Physics, University of Utah, 201 Presidents Circle, Salt Lake City, Utah 84112 (United States)

2009-03-10

366

Radiation tolerance of a high quality synthetic single crystal chemical vapor deposition diamond detector irradiated by 14.8 MeV neutrons  

NASA Astrophysics Data System (ADS)

Diamond exhibits many properties such as an outstanding radiation hardness and fast response time both important to design detectors working in extremely radioactive environments. Among the many applications these devices can be used for, there is the development of a fast and radiation hard neutron detector for the next generation of fusion reactors, such as the International Thermonuclear Experimental Reactor project, under construction at Cadarache in France. A technology to routinely produce electronic grade synthetic single crystal diamond detectors was recently developed by our group. One of such detectors, with an energy resolution of 0.9% as measured using an A241m ? particle source, has been heavily irradiated with 14.8 MeV neutrons produced by the Frascati Neutron Generator. The modifications of its spectroscopic properties have been studied as a function of the neutron fluence up to 2.0×1014 n/cm2. In the early stage of the irradiation procedure an improvement in the spectroscopic performance of the detector was observed. Subsequently the detection performance remains stable for all the given neutron fluence up to the final one thus assessing a remarkable radiation hardness of the device. The neutron damage in materials has been calculated and compared with the experimental results. This comparison is discussed within the nonionizing energy loss (NIEL) hypothesis, which states that performance degradation is proportional to NIEL.

Pillon, M.; Angelone, M.; Aielli, G.; Almaviva, S.; Marinelli, Marco; Milani, E.; Prestopino, G.; Tucciarone, A.; Verona, C.; Verona-Rinati, G.

2008-09-01

367

Assessment of radiation doses from residential smoke detectors that contain americium-241  

SciTech Connect

External dose equivalents and internal dose commitments were estimated for individuals and populations from annual distribution, use, and disposal of 10 million ionization chamber smoke detectors that contain 110 kBq (3 ..mu..Ci) americium-241 each. Under exposure scenarios developed for normal distribution, use, and disposal using the best available information, annual external dose equivalents to average individuals were estimated to range from 4 fSv (0.4 prem) to 20 nSv (2 ..mu..rem) for total body and from 7 fSv to 40 nSv for bone. Internal dose commitments to individuals under post disposal scenarios were estimated to range from 0.006 to 80 ..mu..Sv (0.0006 to 8 mrem) to total body and from 0.06 to 800 ..mu..Sv to bone. The total collective dose (the sum of external dose equivalents and 50-year internal dose commitments) for all individuals involved with distribution, use, or disposal of 10 million smoke detectors was estimated to be about 0.38 person-Sv (38 person-rem) to total body and 00 ft/sup 2/).

O'Donnell, F.R.; Etnier, E.L.; Holton, G.A.; Travis, C.C.

1981-10-01

368

Assessment of radiation doses from residential smoke detectors that contain americium-241  

NASA Astrophysics Data System (ADS)

External dose equivalents and internal dose commitments were estimated for individuals and populations from annual distribution, use, and disposal of 10 million ionization chamber smoke detectors that contain 110 kBq americium-241 each. Under exposure scenarios developed for normal distribution, use, and disposal using the best available information, annual external dose equivalents to average individuals were estimated to range from 4 fSv to 20 nSv for total body and from 7 fSv to 40 nSv for bone. Internal dose commitments to individuals under post disposal scenarios were estimated to range from 0.006 to 80 micro-Sv (0.0006 to 8 mrem) to total body and from 0.06 to 800 micro-Sv to bone. The total collective dose (the sum of external dose equivalents and 50-year internal dose commitments) for all individuals involved with distribution, use, or disposal of 10 million smoke detectors was estimated to be about 0.38 person-Sv (38 person-rem) to total body and 00 ft squared.

Odonnell, F. R.; Etnier, E. L.; Holton, G. A.; Travis, C. C.

1981-10-01

369

Correction for scattered radiation in a ring detector positron camera by integral transformation of the projections  

Microsoft Academic Search

A deconvolution algorithm for the determination of the scatter contribution in positron emission tomography is described. The projected distributions of scattered radiation measured with a line source at different positions in water phantoms are described analytically. It is shown that an integral transformation of the observed projections with a slightly modified analytical function gives an adequate description of the scattered

M. Bergstroem; L. Eriksson; C. Bohm; G. Blomqvist; J. Litton

1983-01-01

370

Ultrasonic helium detectors applied in oxygen deficiency hazard monitor system in radiation environment  

Microsoft Academic Search

The prototype ultrasonic sound velocity measuring system was designed and built at Wroclaw University of Technology. The system aims to detect helium release into the air in a quantity that may cause oxygen deficiency hazard (ODH) and is also dedicated to work in radiation conditions. In order to qualify the measuring system to be used in accelerator tunnels, the stability

W. Gizicki; M. Chorowski

2007-01-01

371

Standoff Performance of HPGe Detectors in Identification of Gamma-Ray Radiation Sources  

Microsoft Academic Search

The detection and identification of radiation sources at distances in the range of 15 meters or more is becoming increasingly important for illicit materials interdiction and the location of lost or orphan sources. In most locations, there is a considerable gamma-ray flux from natural background (NORM) and cosmic- induced nuclides. This gamma-ray flux varies with time, weather conditions, location, and

Ronald M. Keyser; Timothy R. Twomey; Sam Hitch

372

Temporal and temperature evolution of electric field in CdTe:In radiation detectors  

NASA Astrophysics Data System (ADS)

We employed measurement of the Pockels electro-optic effect to study the electric field and space charge dynamics in semi-insulating CdTe doped with indium. We performed measurements of time and temperature dependence of the electric field. The polarization due to space charge build-up decreases with increasing temperature. Increase of temperature, therefore, leads to de-polarization in CdTe:In detectors which are opposite to the CdTe:Cl samples studied to date. We have shown that the thermally activated depolarization cannot be explained by the conventional model used for the description of space charge formation so far and an alternative model involving a recombination level was suggested and successfully used.

D?di?, V.; Zázvorka, J.; Rejhon, M.; Franc, J.; Grill, R.; Sellin, P. J.

2014-08-01

373

GaAs pixel radiation detector as an autoradiography tool for genetic studies  

NASA Astrophysics Data System (ADS)

We present an autoradiography tool to be used mainly for genetic studies. It performs a quantitative analysis of radioactivity and can follow a dynamic process. We designed several applications, in particular one aimed at detecting hybridization of radio-labeled DNA fragments with known DNA-probes deposited on a micro-array. The technique is based on GaAs pixel array detector and low threshold, large dynamic range and good sensitivity integrated electronics developed for medical applications, suitable to detect markers (gamma or beta) such as 14C, 35S, 33P, 32P, 125I, even at very low activities. A Monte Carlo simulation of ?- detection in GaAs is presented here in order to study the spatial resolution characteristics of such a system. For several biological applications, the electronics is required to perform at high temperatures (from 37° to 68°): we present here studies of noise and minimum threshold as a function of the temperature.

Bertolucci, E.; Conti, M.; Mettivier, G.; Russo, P.; Amendolia, S. R.; Bisogni, M. G.; Bottigli, U.; Ceccopieri, A.; Ciocci, M. A.; Delogu, P.; Fantacci, M. E.; Maestro, P.; Marzulli, V. M.; Pernigotti, E.; Romeo, N.; Rosso, V.; Stefanini, A.; Stumbo, S.

1999-02-01

374

Interfacial Chemistry and the Performance of Bromine-etched CdZnTe Radiation Detector Devices  

SciTech Connect

The interfacial chemistry and composition of Pt electrodes sputter deposited on bromine-etched CdZnTe surfaces was studied by XPS, SIMS, AES, NRA and RBS. The interfacial composition of a functioning and a non-functioning CdZnTe detector shows significant differences. The degree of cation out-diffusion into the Pt overlayer and the in-diffusion of Pt into the CdZnTe correlate with the degree of oxidation found at the metal-semiconductor interface. Practically all the oxide present at the interface was found to be TeO{sub 2}. The results suggest that the inter-diffusion of the atoms and associated charges contribute to stoichiometric variations at the metal-semiconductor interface and influence the electrical performance of the devices.

Rouse, Ambrosio A.; Szeles, Csaba; Ndap, Jean-Oliver; Soldner, Steve; Parnham, K B.; Gaspar, Dan J.; Engelhard, Mark H.; Lea, Alan S.; Shutthanandan, V; Thevuthasan, Suntharampillai; Baer, Donald R.

2002-08-01

375

Application of a-Si:H radiation detectors in medical imaging  

SciTech Connect

Monte Carlo simulations of a proposed a-Si:H-based current-integrating gamma camera were performed. The analysis showed that the intrinsic resolution of such a camera was 1 {approximately} 2.5 mm, which is somewhat better than that of a conventional gamma camera, and that the greater blurring, due to the detection of scattered {gamma}-rays, could be reduced considerably by image restoration techniques. This proposed gamma camera would be useful for imaging shallow organs such as the thyroid. Prototype charge-storage a-Si:H pixel detectors for such a camera were designed, constructed and tested. The detectors could store signal charge as long as 5 min at {minus}26C. The thermal generation current in reverse biased a-Si:H p-i-n photodetectors was investigated, and the Poole-Frenkel effect was found to be the most significant source of the thermal generation current. Based on the Poole-Frenkel effect, voltage- and time-dependent thermal generation current was modeled. Using the model, the operating conditions of the proposed a-Si:H gamma camera, such as the operating temperature, the operating bias and the {gamma}-scan period, could be predicted. The transient photoconductive gain mechanism in various a-Si:H devices was investigated for applications in digital radiography. Using the a-Si:H photoconductors in n-i-n configuration in pixel arrays, enhancement in signal collection (more than 200 times higher signal level) can be achieved in digital radiography, compared to the ordinary p-i-n type a-Si:H x-ray imaging arrays.

Lee, Hyoung-Koo

1995-06-01

376

Shielded Heavy-Ion Environment Linear Detector (SHIELD): an experiment for the Radiation and Technology Demonstration (RTD) Mission  

NASA Technical Reports Server (NTRS)

Radiological assessment of the many cosmic ion species of widely distributed energies requires the use of theoretical transport models to accurately describe diverse physical processes related to nuclear reactions in spacecraft structures, planetary atmospheres and surfaces, and tissues. Heavy-ion transport models that were designed to characterize shielded radiation fields have been validated through comparison with data from thick-target irradiation experiments at particle accelerators. With the RTD Mission comes a unique opportunity to validate existing radiation transport models and guide the development of tools for shield design. For the first time, transport properties will be measured in free-space to characterize the shielding effectiveness of materials that are likely to be aboard interplanetary space missions. Target materials composed of aluminum, advanced composite spacecraft structure and other shielding materials, helium (a propellant) and tissue equivalent matrices will be evaluated. Large solid state detectors will provide kinetic energy and charge identification for incident heavy-ions and for secondary ions created in the target material. Transport calculations using the HZETRN model suggest that 8 g cm -2 thick targets would be adequate to evaluate the shielding effectiveness during solar minimum activity conditions for a period of 30 days or more.

Shavers, M. R.; Cucinotta, F. A.; Miller, J.; Zeitlin, C.; Heilbronn, L.; Wilson, J. W.; Singleterry, R. C. Jr

2001-01-01

377

New CID detectors/cameras for use in ionizing radiation environments  

SciTech Connect

New high-resolution silicon-based charge injection device (CID) imagers and CID-based television (TV)-compatible video cameras were developed to operate in ionizing radiation environments. Excellent video images were obtained in the presence of exposure levels (in silicon) of 1 Mrad/h and 10 Mrads accumulated dose from a {sup 60}Co source. The cameras incorporate unique radiation-hardened CID solid-state imager technology and possess formats that are compatible with European (CCIR-768{sub H} X 575{sub v}) and American (RS170-755{sub H} X 484{sub v}) TV systems. These products provide an economical, reliable solid state alternative to tube-based cameras now used as monitoring and diagnostic tools in nuclear power generation, waste disposal, and scientific applications.

Carbone, J.; Czebiniak, S.; Zarnowski, J. [CID Technologies, Inc., Liverpool, NY (United States)

1995-12-31

378

Ultrasonic helium detectors applied in oxygen deficiency hazard monitor system in radiation environment  

NASA Astrophysics Data System (ADS)

The prototype ultrasonic sound velocity measuring system was designed and built at Wroclaw University of Technology. The system aims to detect helium release into the air in a quantity that may cause oxygen deficiency hazard (ODH) and is also dedicated to work in radiation conditions. In order to qualify the measuring system to be used in accelerator tunnels, the stability of the readouts and the durability of the ultrasonic transducers and electronics have been investigated in a radiation environment. Two tests were carried out: one at the European Organization for Nuclear Research CERN in Geneva, and another at the Institute of Atomic Energy (IEA) in Otwock-Swierk near Warsaw, Poland. The readouts were very stable and there was no danger of provoking false alarms of ODH. The accumulated doses absorbed by the system correspond to over 10 years of the large hadron collider (LHC) operation. The developed technology can be considered being used in installations where the oxygen deficiency hazard may be a result of helium release into the air, especially in particle accelerators where the measuring system is threatened by ionizing radiation.

Gizicki, W.; Chorowski, M.

2007-08-01

379

Radiation tests on service electronics for future multi TeV detectors  

NASA Astrophysics Data System (ADS)

Irradiation tests of a number of essential components for use in the service electronics of the Leading Proton Spectrometer (LPS) have been undertaken. The components are simple medium-scale integrated circuits such as Transistor Transistor Logic (TTL) buffers from the Advanced Low-power Schottky (ALS), Low-power Schottky (LS), and Fast (F) families, optocouplers, and balanced line drivers and receivers. More complex circuits, such as a Fuse Programmable Array Logic chip, programmed as a 6-bit counter, and a complete switched-mode power supply unit were also tested. Further, monolithic voltage regulators with an output potential of 5 V, and 10 MHz quartz oscillator hybrids were tested. The different radiation fields were X-rays (80 keV), (sup 60)Co gamma rays, electrons (2.5 MeV), and a high-energy proton accelerator environment. Depending on the device degradation, the maximum dose was up to 0.8 MGy. It is shown that the simple choice of circuit family can achieve a hardness level of nearly 1 MGy(Si), provided that one is prepared to make some sacrifices in power consumption, and in speed. It has been found that this radiation hardness can be reached with LS technology. The maximum level of about 1 MGy(Si) was obtained with 2.5 MeV electrons, which is equivalent to a 1 MeV neutron fluence of the order of 6x10(exp 13)/sq cm.

Larsen, H.; Schoenbacher, H.; Massam, T.; Wulf, F.

1993-10-01

380

Chemical vapor deposition diamond based multilayered radiation detector: Physical analysis of detection properties  

SciTech Connect

Recently, solid state photovoltaic Schottky diodes, able to detect ionizing radiation, in particular, x-ray and ultraviolet radiation, have been developed at the University of Rome 'Tor Vergata'. We report on a physical and electrical properties analysis of the device and a detailed study of its detection capabilities as determined by its electrical properties. The design of the device is based on a metal/nominally intrinsic/p-type diamond layered structure obtained by microwave plasma chemical vapor deposition of homoepitaxial single crystal diamond followed by thermal evaporation of a metallic contact. The device can operate in an unbiased mode by using the built-in potential arising from the electrode-diamond junction. We compare the expected response of the device to photons of various energies calculated through Monte Carlo simulation with experimental data collected in a well controlled experimental setup i.e., monochromatic high flux x-ray beams from 6 to 20 keV, available at the Diamond Light Source synchrotron in Harwell (U.K.).

Almaviva, S.; Marinelli, Marco; Milani, E.; Prestopino, G.; Tucciarone, A.; Verona, C.; Verona-Rinati, G. [Dip. di Ing. Meccanica, Universita di Roma 'Tor Vergata', Roma 00133 (Italy); Angelone, M.; Pillon, M. [Associazione EURATOM-ENEA sulla Fusione, Frascati, Roma 00044 (Italy); Dolbnya, I.; Sawhney, K.; Tartoni, N. [Diamond Light Source, Harwell Science and Innovation Campus, Chilton-Didcot, OX11 0DE Oxfordshire (United Kingdom)

2010-01-15

381

Thick amorphous silicon layers suitable for the realization of radiation detectors  

SciTech Connect

Thick silicon films with good electronic quality have been prepared by glow discharge of He-diluted SiH{sub 4} at a substrate temperature {approximately} 150{degree}C and subsequent annealing at 160{degree}C for about 100 hours. The stress in the films obtained this way decreased to {approximately} 100 MPa compared to the 350 MPa in conventional a-Si:H. The post-annealing helped to reduce the ionized dangling bond density from 2.5 {times} 10{sup 15} cm{sup {minus}3} to 7 {times} 10{sup 14} cm{sup {minus}3} without changing the internal stress. IR spectroscopy and hydrogen effusion measurements implied the existence of microvoids and tiny crystallites in the material showing satisfactory electronic properties. P-I-N diodes for radiation detection applications have been realized out of the new material.

Hong, Wan-Shick; Drewery, J.S.; Jing, Tao; Lee, Hyong-Koo; Perez-Mendez, V. [Lawrence Berkeley Lab., CA (United States); Petrova-Koch, V. [Technische Universitaet Munich, Garching (Germany)

1995-04-01

382

Production of top pair events with additional radiation using the ATLAS detector at the LHC  

E-print Network

The large centre-of-mass energy available at the proton-proton collider LHC allows for the copious production of top quark pairs in association with other final state particles at high transverse momentum. The ATLAS experiment has measured several final state observables that are sensitive to additional parton radiation in top anti-top quark final states. Examples are the multiplicity of jets for various transverse momentum thresholds or the probability to emit jets above a given threshold in a fixed rapidity region. These measurements are compared to modern Monte Carlo generators based on NLO QCD matrix element or LO multi-leg matrix elements. The data are able to constrain the uncertainty on the modelling of the top pair production mechanism. We also discuss top production in association with photons and Z bosons. In addition, we the discuss production of top quark pairs in association with heavy quarks (beauty and charm).

Saaavedra, A; The ATLAS collaboration

2014-01-01

383

Production of top pair events with additional radiation using the ATLAS detector at the LHC  

E-print Network

The large centre-of-mass energy available at the proton-proton collider LHC allows for the copious production of top quark pairs in association with other final state particles at high transverse momentum. The ATLAS experiment has measured several final state observables that are sensitive to additional parton radiation in top anti-top quark final states. Examples are the multiplicity of jets for various transverse momentum thresholds or the probability to emit jets above a given threshold in a fixed rapidity region. These measurements are compared to modern Monte Carlo generators based on NLO QCD matrix element or LO multi-leg matrix elements. The data are able to constrain the uncertainty on the modelling of the top pair production mechanism. We also discuss top production in association with photons and Z bosons. In addition, we discuss the production of top quark pairs in association with heavy quarks.

Bellagamba, L; The ATLAS collaboration

2014-01-01

384

Flame Detector  

NASA Technical Reports Server (NTRS)

Scientific Instruments, Inc. has now developed a second generation, commercially available instrument to detect flames in hazardous environments, typically refineries, chemical plants and offshore drilling platforms. The Model 74000 detector incorporates a sensing circuit that detects UV radiation in a 100 degree conical field of view extending as far as 250 feet from the instrument. It operates in a bandwidth that makes it virtually 'blind' to solar radiation while affording extremely high sensitivity to ultraviolet flame detection. A 'windowing' technique accurately discriminates between background UV radiation and ultraviolet emitted from an actual flame, hence the user is assured of no false alarms. Model 7410CP is a combination controller and annunciator panel designed to monitor and control as many as 24 flame detectors. *Model 74000 is no longer being manufactured.

1990-01-01

385

Detectors for lightwave communication  

Microsoft Academic Search

Lightwave communication links need photodetectors and optical receivers to demodulate the optical signals and to convert them into electrical outputs. Photodetectors include simple thermal detectors, which respond to the energy of the incident radiation, and photon detectors, which respond to the arrival rate of the photons. The photon detectors which were found to be most suitable for lightwave communication at

Hans Melchior

1977-01-01

386

Chemical treatment of CdZnTe radiation detectors using hydrogen bromide and ammonium-based solutions  

NASA Astrophysics Data System (ADS)

Surface damages occur in Cadmium zinc telluride (CdZnTe) wafers for radiation detection devices during dicing and polishing. This often results in increased leakage current that limits the performance of the detector. An effective method of removing the surface damage and thus reducing the leakage current is through the use of chemical treatments. The effects discussed in this study include: chemical polishing with a mixture of hydrogen bromide solution followed by passivation with ammonium fluoride in a hydrogen peroxide solution. The effects on the current-voltage measurements and the spectral response were monitored over a 2-week period. X-ray photoelectron spectroscopy (XPS) was also obtained to observe the formation of chemical species on treated surfaces. The resistivity of the treated CdZnTe samples is on the order of 1010 ohm-cm. The current in the I-V measurements increased rapidly immediately following the chemical polishing and surface passivation, and decreased steadily afterwards. The spectral response showed that the 59.5-keV peak of Am-241 was stable in the same position over the test period.

Okwechime, Ifechukwude O.; Egarievwe, Stephen U.; Hossain, Anwar; Hales, Zaveon M.; Egarievwe, Alexander A.; James, Ralph B.

2014-09-01

387

Assessment of parameters of digital X-ray detectors using the method of exposure of the working area of the detector to uniform X-ray radiation  

Microsoft Academic Search

Until recently, only subjective methods of assessment of parameters of Xray detectors and image quality were used. According to normative documentation, Xray con? trast objects are placed in the input plane of Xray detec? tors during tests (1, 5). The resulting image of the test objects is evaluated by a group of experts. This evaluation has some disadvantages. Xray test

A. I. Mazurov

2007-01-01

388

Polonium–lead extractions to determine the best method for the quantification of clean lead used in low-background radiation detectors  

Microsoft Academic Search

Radiation detectors used to search for the existence of exceptionally rare phenomena, such as double-beta decay and dark matter\\u000a interactions, as well as tiny traces of environmental radioactivity, require the elimination of background signals. Modern\\u000a detection systems created from ultra pure materials and operated deep underground may be sensitive enough to “see” these rare\\u000a phenomena, but background activity in Pb

Sarah M. Miley; Rosara F. Payne; Shannon M. Schulte; Erin C. Finn

2009-01-01

389

Subcellular Biochemical Investigation of Purkinje Neurons Using Synchrotron Radiation Fourier Transform Infrared Spectroscopic Imaging with a Focal Plane Array Detector  

PubMed Central

Coupling Fourier transform infrared spectroscopy with focal plane array detectors at synchrotron radiation sources (SR-FTIR-FPA) has provided a rapid method to simultaneously image numerous biochemical markers in situ at diffraction limited resolution. Since cells and nuclei are well resolved at this spatial resolution, a direct comparison can be made between FTIR functional group images and the histology of the same section. To allow histological analysis of the same section analyzed with infrared imaging, unfixed air-dried tissue sections are typically fixed (after infrared spectroscopic analysis is completed) via immersion fixation. This post fixation process is essential to allow histological staining of the tissue section. Although immersion fixation is a common practice in this filed, the initial rehydration of the dehydrated unfixed tissue can result in distortion of subcellular morphology and confound correlation between infrared images and histology. In this study, vapor fixation, a common choice in other research fields where postfixation of unfixed tissue sections is required, was employed in place of immersion fixation post spectroscopic analysis. This method provided more accurate histology with reduced distortions as the dehydrated tissue section is fixed in vapor rather than during rehydration in an aqueous fixation medium. With this approach, accurate correlation between infrared images and histology of the same section revealed that Purkinje neurons in the cerebellum are rich in cytosolic proteins and not depleted as once thought. In addition, we provide the first direct evidence of intracellular lactate within Purkinje neurons. This highlights the significant potential for future applications of SR-FTIR-FPA imaging to investigate cellular lactate under conditions of altered metabolic demand such as increased brain activity and hypoxia or ischemia. PMID:23638613

2013-01-01

390

Superior CT coronary angiography image quality at lower radiation exposure with second generation 320-detector row CT in patients with elevated heart rate: a comparison with first generation 320-detector row CT  

PubMed Central

Background This study aims to compare the image quality of second generation versus first generation 320-computed tomography coronary angiography (CTCA) in patients with heart rate ?65 bpm as it has not been specifically reported. Methods Consecutive patients who underwent CTCA using second-generation-320-detector-row-CT were prospectively enrolled. A total of 50 patients with elevated (?65 bpm) heart rate and 50 patients with controlled (<65 bpm) heart rate were included. Age and gender matched patients who were scanned with the first-generation-320-detector-row-CT were retrospectively identified. Image quality in each coronary artery segment was assessed by two blinded CT angiographers using the five-point Likert scale. Results In the elevated heart rate cohorts, while there was no significant difference in heart rate during scan-acquisition (66 vs. 69 bpm, P=0.308), or body mass index (28.5 vs. 29.6, P=0.464), the second generation scanner was associated with better image quality (3.94±0.6 vs. 3.45±0.8, P=0.001), and with lower radiation (2.8 vs. 4.3 mSv, P=0.009). There was no difference in scan image quality for the controlled heart rate cohorts. Conclusions The second generation CT scanner provides better image quality at lower radiation dose in patients with elevated heart rate (?65 bpm) compared to first generation CT scanner. PMID:25276615

Soh, Siang Y.; Ko, Brian S. H.; Cameron, James D.; Crossett, Marcus; Nasis, Arthur; Troupis, John; Meredith, Ian T.; Seneviratne, Sujith K.

2014-01-01

391

Invited Review Article: Physics and Monte Carlo techniques as relevant to cryogenic, phonon, and ionization readout of Cryogenic Dark Matter Search radiation detectors  

SciTech Connect

This review discusses detector physics and Monte Carlo techniques for cryogenic, radiation detectors that utilize combined phonon and ionization readout. A general review of cryogenic phonon and charge transport is provided along with specific details of the Cryogenic Dark Matter Search detector instrumentation. In particular, this review covers quasidiffusive phonon transport, which includes phonon focusing, anharmonic decay, and isotope scattering. The interaction of phonons in the detector surface is discussed along with the downconversion of phonons in superconducting films. The charge transport physics include a mass tensor which results from the crystal band structure and is modeled with a Herring-Vogt transformation. Charge scattering processes involve the creation of Neganov-Luke phonons. Transition-edge-sensor (TES) simulations include a full electric circuit description and all thermal processes including Joule heating, cooling to the substrate, and thermal diffusion within the TES, the latter of which is necessary to model normal-superconducting phase separation. Relevant numerical constants are provided for these physical processes in germanium, silicon, aluminum, and tungsten. Random number sampling methods including inverse cumulative distribution function (CDF) and rejection techniques are reviewed. To improve the efficiency of charge transport modeling, an additional second order inverse CDF method is developed here along with an efficient barycentric coordinate sampling method of electric fields. Results are provided in a manner that is convenient for use in Monte Carlo and references are provided for validation of these models.

Leman, Steven W. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2012-09-15

392

Invited review article: physics and Monte Carlo techniques as relevant to cryogenic, phonon, and ionization readout of Cryogenic Dark Matter Search radiation detectors.  

PubMed

This review discusses detector physics and Monte Carlo techniques for cryogenic, radiation detectors that utilize combined phonon and ionization readout. A general review of cryogenic phonon and charge transport is provided along with specific details of the Cryogenic Dark Matter Search detector instrumentation. In particular, this review covers quasidiffusive phonon transport, which includes phonon focusing, anharmonic decay, and isotope scattering. The interaction of phonons in the detector surface is discussed along with the downconversion of phonons in superconducting films. The charge transport physics include a mass tensor which results from the crystal band structure and is modeled with a Herring-Vogt transformation. Charge scattering processes involve the creation of Neganov-Luke phonons. Transition-edge-sensor (TES) simulations include a full electric circuit description and all thermal processes including Joule heating, cooling to the substrate, and thermal diffusion within the TES, the latter of which is necessary to model normal-superconducting phase separation. Relevant numerical constants are provided for these physical processes in germanium, silicon, aluminum, and tungsten. Random number sampling methods including inverse cumulative distribution function (CDF) and rejection techniques are reviewed. To improve the efficiency of charge transport modeling, an additional second order inverse CDF method is developed here along with an efficient barycentric coordinate sampling method of electric fields. Results are provided in a manner that is convenient for use in Monte Carlo and references are provided for validation of these models. PMID:23020355

Leman, Steven W

2012-09-01

393

Non-reference condition correction factor kNR of typical radiation detectors applied for the dosimetry of high-energy photon fields in radiotherapy.  

PubMed

According to accepted dosimetry protocols, the "radiation quality correction factor"k(Q) accounts for the energy-dependent changes of detector responses under the conditions of clinical dosimetry for high-energy photon radiations. More precisely, a factor k(QR) is valid under reference conditions, i.e. at a point on the beam axis at depth 10 cm in a large water phantom, for 10×10 cm(2) field size, SSD 100 cm and the given radiation quality with quality index Q. Therefore, a further correction factor k(NR) has been introduced to correct for the influences of spectral quality changes when detectors are used under non-reference conditions such as other depths, field sizes and off-axis distances, while under reference conditions k(NR) is normalized to unity. In this paper, values of k(NR) are calculated for 6 and 15 MV photon beams, using published data of the energy-dependent responses of various radiation detectors to monoenergetic photon radiations, and weighting these responses with validated photon spectra of clinical high-energy photon beams from own Monte-Carlo-calculations for a wide variation of the non-reference conditions within a large water phantom. Our results confirm the observation by Scarboro et al. [26] that k(NR) can be represented by a unique function of the mean energy Em, weighted by the spectral photon fluence. Accordingly, the numerical variations of Em with depth, field size and off-axis distance have been provided. Throughout all considered conditions, the deviations of the k(NR) values from unity are at most 2% for a Farmer type ion chamber, and they remain below 15% for the thermoluminescent detectors LiF:Mg,Ti and LiF:Mg,Cu,P. For the shielded diode EDP-10, k(NR) varies from unity up to 20%, while the unshielded diode EDD-5 shows deviations up to 60% in the peripheral region. Thereby, the restricted application field of unshielded diodes has been clarified. For small field dosimetry purposes k(NR) can be converted into k(NCSF), the non-calibration condition correction factor normalized to unity for a 4×4 cm(2) calibration field. For the unshielded Si diodes needed in small-field dosimetry, the values of k(NCSF) are closer to unity than the associated k(NR) values. PMID:22658451

Chofor, Ndimofor; Harder, Dietrich; Poppe, Björn

2012-09-01

394

Radiation tolerance characterization of dual band InAs/GaSb type-II strain-layer superlattice pBp detectors using 63 MeV protons  

SciTech Connect

The radiation tolerance characterization of dual band InAs/GaSb type-II strain-layer superlattice pBp detectors of varying size using 63 MeV proton irradiation is presented. The detectors' mid-wave infrared performance degraded with increasing proton fluence {Phi}{sub P} up to 3.75 Multiplication-Sign 10{sup 12} cm{sup -2} or, equivalently, a total ionizing dose = 500 kRad (Si). At this {Phi}{sub P}, an {approx}31% drop in quantum efficiency {eta}, {approx}2 order increase in dark current density J{sub D}, and consequently, >1 order drop in calculated detectivity D* were observed. Proton damage factors were determined for {eta} and D*. Arrhenius-analysis of temperature-dependent J{sub D} measurements reflected significant changes in the activation energies following irradiation.

Cowan, V. M.; Morath, C. P.; Hubbs, J. E. [Air Force Research Laboratory, Space Vehicles Directorate, 3550 Aberdeen Ave. SE, Kirtland AFB, New Mexico 87117 (United States); Myers, S.; Plis, E.; Krishna, S. [Center for High Technology Materials, Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico 87106 (United States)

2012-12-17

395

Analysis of 3D silicon pixel vertex detector damage effects due to radiation levels present in the LHC at CERN  

E-print Network

In high energy physics experiments, very high precision tracking of charged particles is needed. Solid state detectors achieve the high precision necessary to provide track and vertex reconstruction of the particles that ...

Chapa, Matthew R

2012-01-01

396

Reducing the Radiation Dose During Excretory Urography: Flat-Panel Silicon X-Ray Detector Versus Computed Radiography  

Microsoft Academic Search

OBJECTIVE. The purpose of the study was to examine the possibilities for reducing radi- ation exposure in uroradiology using digital flat-panel silicon X-ray detector radiography. We compared the subjectively determined image quality of abdominal radiographs and urograms obtained on a digital flat-panel detector radiography system with those obtained on a com- puted radiography system. SUBJECTS AND METHODS. Fifty patients who

V. Hesselmann; O. Schulte; K. F. Kamm; W. Braun; G. Haupt; B. Krug; K. Lackner

397

Femtosecond Radiation Experiment Detector for X-Ray Free-Electron Laser (XFEL) Coherent X-Ray Imaging  

Microsoft Academic Search

A pixel array detector (PAD) module has been developed at Cornell University for the collection of diffuse diffraction data in anticipation of coherent X-ray imaging experiments that will be conducted at the Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Laboratory. The detector is designed to collect X-rays scattered from monochromatic femtosecond pulses produced by the LCLS X-ray

Hugh T. Philipp; Lucas J. Koerner; Marianne S. Hromalik; Mark W. Tate; Sol M. Gruner

2010-01-01

398

Radiation dosimeter  

DOEpatents

A radiation detector readout circuit is provided which produces a radiation dose-rate readout from a detector even though the detector output may be highly energy dependent. A linear charge amplifier including an output charge pump circuit amplifies the charge signal pulses from the detector and pumps the charge into a charge storage capacitor. The discharge rate of the capacitor through a resistor is controlled to provide a time-dependent voltage which when integrated provides an output proportional to the dose-rate of radiation detected by the detector. This output may be converted to digital form for readout on a digital display.

Fox, Richard J. (Oak Ridge, TN)

1983-01-01

399

Radiation dosimeter  

DOEpatents

A radiation detector readout circuit is provided which produces a radiation dose-rate readout from a detector even through the detector output may be highly energy dependent. A linear charge amplifier including an output charge pump circuit amplifies the charge signal pulses from the detector and pumps the charge into a charge storage capacitor. The discharge rate of the capacitor through a resistor is controlled to provide a time-dependent voltage which when integrated provides an output proportional to the dose-rate of radiation detected by the detector. This output may be converted to digital form for readout on a digital display.

Fox, R.J.

1981-09-01

400

Radiation dose reduction using a CdZnTe-based computed tomography system: Comparison to flat-panel detectors  

PubMed Central

Purpose: Although x-ray projection mammography has been very effective in early detection of breast cancer, its utility is reduced in the detection of small lesions that are occult or in dense breasts. One drawback is that the inherent superposition of parenchymal structures makes visualization of small lesions difficult. Breast computed tomography using flat-panel detectors has been developed to address this limitation by producing three-dimensional data while at the same time providing more comfort to the patients by eliminating breast compression. Flat panels are charge integrating detectors and therefore lack energy resolution capability. Recent advances in solid state semiconductor x-ray detector materials and associated electronics allow the investigation of x-ray imaging systems that use a photon counting and energy discriminating detector, which is the subject of this article. Methods: A small field-of-view computed tomography (CT) system that uses CdZnTe (CZT) photon counting detector was compared to one that uses a flat-panel detector for different imaging tasks in breast imaging. The benefits afforded by the CZT detector in the energy weighting modes were investigated. Two types of energy weighting methods were studied: Projection based and image based. Simulation and phantom studies were performed with a 2.5 cm polymethyl methacrylate (PMMA) cylinder filled with iodine and calcium contrast objects. Simulation was also performed on a 10 cm breast specimen. Results: The contrast-to-noise ratio improvements as compared to flat-panel detectors were 1.30 and 1.28 (projection based) and 1.35 and 1.25 (image based) for iodine over PMMA and hydroxylapatite over PMMA, respectively. Corresponding simulation values were 1.81 and 1.48 (projection based) and 1.85 and 1.48 (image based). Dose reductions using the CZT detector were 52.05% and 49.45% for iodine and hydroxyapatite imaging, respectively. Image-based weighting was also found to have the least beam hardening effect. Conclusions: The results showed that a CT system using an energy resolving detector reduces the dose to the patient while maintaining image quality for various breast imaging tasks. PMID:20384260

Le, Huy Q.; Ducote, Justin L.; Molloi, Sabee

2010-01-01

401

Peculiarities of applying the ?{/n k } criterion for the electron identification problem based on the transition radiation detector in the compressed baryonic matter experiment  

NASA Astrophysics Data System (ADS)

The problem of electron identification under conditions of a dominating pion background with the help of a multilayered transition radiation detector (TRD) in the Compressed Baryonic Matter (CBM) experiment is considered. With this aim, various mathematical methods, including methods based on the nonparametric goodness-of-fit ?{/n k } criterion, have been elaborated and investigated. The characteristic properties of distributions of energy losses by electrons and pions in the TRD radiators are considered, and specific features of applying traditional statistical methods, methods based on the ?{/n k } criterion, and artificial neural networks to the analyzed problem are discussed. The results of a comparative analysis of the power of these methods are presented, and recommendations for their usage are given.

Akishina, T. P.

2012-05-01

402

Optical proximity detector  

NASA Technical Reports Server (NTRS)

Sensitive, relatively inexpensive instrument uses phase-detection techniques to sense presence of objects. Phase-sensitive detectors, LED, photodiode with response matched to LED output, and filtering lens allow detector to operate over narrow radiation band, giving selectivity over stray light.

Hermann, W. A.; Johnston, A. R.

1977-01-01

403

Quantum Imaging X—ray CT Systems Based on GaAs Radiation Detectors Using Perspective Imaging Reconstruction Techniques  

NASA Astrophysics Data System (ADS)

The work presents two generations of developed portable quantum X—CT mini-systems which utilize monolithic semi-insulating GaAs detectors. This contribution describes the present status of the assembling of the new portable X—ray CT mini system. Developed modification of the X—ray image reconstruction based on perspective imaging techniques has been experimentally verified on testing phantoms and practically implemented for processing images of real test objects. Performed measurement of the performance of the SI GaAs detectors and the integral spectra of ASIC DX64 readout chips are also mentioned.

P?ibil, J.; Zat'ko, B.; Frollo, I.; Dubecký, F.; Š?epko, P.; Mudro?, J.

2009-01-01

404

Quantum dosimetry and online visualization of X-ray and charged particle radiation in commercial aircraft at operational flight altitudes with the pixel detector Timepix  

NASA Astrophysics Data System (ADS)

We investigate the application of the hybrid semiconductor pixel detector Timepix for precise characterization, quantum sensitivity dosimetry and visualization of the charged particle radiation and X-ray field inside commercial aircraft at operational flight altitudes. The quantum counting capability and granularity of Timepix provides the composition and spectral-characteristics of the X-ray and charged-particle field with high sensitivity, wide dynamic range, high spatial resolution and particle type resolving power. For energetic charged particles the direction of trajectory and linear energy transfer can be measured. The detector is operated by the integrated readout interface FITPix for power, control and data acquisition together with the software package Pixelman for online visualization and real-time data processing. The compact and portable radiation camera can be deployed remotely being controlled simply by a laptop computer. The device performs continuous monitoring and accurate time-dependent measurements in wide dynamic range of particle fluxes, deposited energy, absorbed dose and equivalent dose rates. Results are presented for in-flight measurements at altitudes up to 12 km in various flights selected in the period 2006-2013.

Granja, Carlos; Pospisil, Stanislav

2014-07-01

405

Characterisation of neutron-sensitive bubble detectors for application in the measurement of jet aircrew exposure to natural background radiation.  

PubMed

A survey of the natural background dose equivalent received by Canadian Forces aircrew was conducted using neutron-sensitive bubble detectors (BDs) as the primary detection tool. Since this study was a new application for these detectors, the BD response to neutron dose equivalent (RD) was extended from thermal to 500 MeV in neutron energy. Based upon the extended RD, it was shown that the manufacturer's calibration can be scaled by 1.5 +/- 0.5 to give a BD sensitivity that takes into account recently recommended fluence-to-neutron dose equivalent conversion functions and the cosmogenic neutron spectrum encountered at jet altitudes. An investigation of the effects of systematic bias caused by the cabin environment (i.e., temperature, pressure and relative humidity) on the in-flight measurements was also conducted. Both simulated and actual aircraft climate tests indicated that the detectors are insensitive to the pressure and relative humidity variations encountered during routine jet aircraft operations. Long term conditioning tests also confirmed that the BD-PND model of detector is sensitive to variations in temperature to within +/- 20%. As part of the testing process, the in-flight measurements also demonstrated that the neutron dose equivalent is distributed uniformly throughout a Boeing 707 jet aircraft, indicating that both pilots and flight attendants are exposed to the same neutron field intensity to within experimental uncertainty. PMID:11542590

Tume, P; Lewis, B J; Bennett, L G; Cousins, T

1998-01-01

406

Characterisation of neutron-sensitive bubble detectors for application in the measurement of jet aircrew exposure to natural background radiation  

NASA Astrophysics Data System (ADS)

A survey of the natural background dose equivalent received by Canadian Forces aircrew was conducted using neutron-sensitive bubble detectors (BDs) as the primary detection tool. Since this study was a new application for these detectors, the BD response to neutron dose equivalent (RD) was extended from thermal to 500 MeV in neutron energy. Based upon the extended RD, it was shown that the manufacturer's calibration can be scaled by 1.5±0.5 to give a BD sensitivity that takes into account recently recommended fluence-to-neutron dose equivalent conversion functions and the cosmogenic neutron spectrum encountered at jet altitudes. An investigation of the effects of systematic bias caused by the cabin environment (i.e., temperature, pressure and relative humidity) on the in-flight measurements was also conducted. Both simulated and actual aircraft climate tests indicated that the detectors are insensitive to the pressure and relative humidity variations encountered during routine jet aircraft operations. Long term conditioning tests also confirmed that the BD-PND model of detector is sensitive to variations in temperature to within ±20%. As part of the testing process, the in-flight measurements also demonstrated that the neutron dose equivalent is distributed uniformly throughout a Boeing 707 jet aircraft, indicating that both pilots and flight attendants are exposed to the same neutron field intensity to within experimental uncertainty.

Tume, P.; Lewis, B. J.; Bennett, L. G. I.; Cousins, T.

407

Determination of optimal boundary for algorithmic method of plastic scintillator-based radiation detector against nuclear terrorism  

Microsoft Academic Search

A plastic scintillator-based radiation portal monitoring system has played an important role in preventing and detecting illicit trafficking of nuclear and radioactive materials. The limited spectroscopic information of the plastic scintillator material makes it difficult to discriminate radioactive materials of concern from naturally occurring radioactive materials (NORM) or background radiation. This has an impact on operations and surveillance costs. Various

Sung-Woo Kwak; Sung Soon Jang; Ho-Sik Yoo

2010-01-01

408

The HOTWAXS detector  

NASA Astrophysics Data System (ADS)

The development and testing of the HOTWAXS position-sensitive X-ray detector for Synchrotron Radiation Sources is described. Funded from a facility development grant, the aim of the project was to produce a high counting rate, parallax-free photon counting detector to be used in the combined studies of X-ray absorption fine structure and X-ray diffraction (XAFS/XRD), and also in the technique of small angle and wide angle X-ray scattering (SAXS/WAXS). The detector system is described together with results of experiments carried out at the Daresbury Laboratory Synchrotron Radiation Source.

Bateman, J. E.; Derbyshire, G. E.; Diakun, G.; Duxbury, D. M.; Fairclough, J. P. A.; Harvey, I.; Helsby, W. I.; Lipp, J. D.; Marsh, A. S.; Salisbury, J.; Sankar, G.; Spill, E. J.; Stephenson, R.; Terrill, N. J.

2007-10-01

409

New electronically black neutron detectors  

SciTech Connect

Two neutron detectors are described that can function in a continuous radiation background. Both detectors identify neutrons by recording a proton recoil pulse followed by a characteristic capture pulse. This peculiar signature indicates that the neutron has lost all its energy in the scintillator. Resolutions and efficiencies have been measured for both detectors.

Drake, D.M.; Feldman, W.C.; Hurlbut, C.

1986-03-01

410

Detectors of gravitational waves  

NASA Astrophysics Data System (ADS)

Gravitational waves Motion of test bodies in a g.w. field Energy carried by gravitational waves Gravitational-wave sources Spinning star Double-star systems Fall into a Schwarzschild black hole Radiation from gravitational collapse Gravitational-wave detectors The nonresonant detectors The resonant detectors Electromechnical transducers Piezoelectric ceramic The capacitor The inductor Data analysis The Brownian noise The back-action The wide-band noise, data analysis and optimization The resonant transducer The Wiener-Kolmogoroff filter The cross-section and the effective temperature The antenna bandwidth The gravitational-wave experiments in the world The laser interferometers The resonant detectors

Pizzella, G.

411

Study of the characteristics of a piezoelectric lead zirconate titanate radiation detector using a pulsed xenon source  

SciTech Connect

The detector characteristics of piezoelectric lead zirconate titanate (PZT) were studied by directly irradiating a multilayered PZT detector with 400 MeV/n xenon ions. An extracted beam was processed with a rotating slit. Thus, passed through {approx}10{sup 3} xenon ions were available for 50 to 250 {mu}s. The effect of polarization on the output signal was discussed, and the optimal electrode configuration was determined. The output signal appeared as an isolated pulse whose amplitude was qualitatively understood by the Bethe-Bloch formula. However, the calculated and the observed values differed depending on the rotation speed of the slit. A process that can explain the differences is presented here. The output signal appearing beyond the range of 400 MeV/n xenon ion beam was discussed. The sensitivity was compared with that obtained with hypervelocity collision of dust.

Miyachi, Takashi [Research Institute of Science and Engineering, Waseda University, Tokyo 169-8555 (Japan); Planetary Exploration Research Center, Chiba Institute of Technology, Narashino, Chiba 275-0016 (Japan); Fujii, Masayuki; Hasebe, Nobuyuki; Okudaira, Osamu [Research Institute of Science and Engineering, Waseda University, Tokyo 169-8555 (Japan); Takechi, Seiji; Kurozumi, Atsuma; Morinaga, Shinya; Uno, Takefumi [Graduate School of Engineering, Osaka-City University, Osaka 558-8585 (Japan); Shibata, Hiromi [Graduate School of Engineering, Kyoto-University, Kyoto-606-8501 (Japan); Kobayashi, Masanori [Planetary Exploration Research Center, Chiba Institute of Technology, Narashino, Chiba 275-0016 (Japan); Murakami, Takeshi; Uchihori, Yukio [National Institute of Radiological Sciences, Chiba 263-8555 (Japan); Okada, Nagaya [Honda Electronics Co. Ltd., Toyohashi, Aichi 441-3193 (Japan)

2010-05-15

412

CdZnTe and CdTe materials for X-ray and gamma ray radiation detector applications  

Microsoft Academic Search

Good detection efficiency and high energy-resolution make Cadmium Zinc Telluride (CdZnTe) and Cadmium Telluride (CdTe) detectors attractive in many room temperature X-ray and gamma-ray detection applications such as medical and industrial imaging, industrial gauging and non-destructive testing, security and monitoring, nuclear safeguards and non-proliferation, and astrophysics. Advancement of the crystal growth and device fabrication technologies and the reduction of bulk,

Csaba Szeles

2004-01-01

413

Study of cadmium zinc telluride (CZT) radiation detector modules under moderate and long-term variations of temperature and humidity  

Microsoft Academic Search

A gamma camera, assembled from radiation imaging modules based on cadmium zinc telluride (CZT), has been studied under moderate and long-term variations of temperature (15degC to 40degC) and humidity (10% to 70%). Over one year we acquired energy spectra from radiation sources and we measured the photo-peak position and energy resolution. We observe that the camera remains within the desired

G. Mashlum; Knut I. Dietzel; Dirk Meier; Marek Szawlowski; Bjørn Sundal; Thor Vandehei; Douglas Wagenaar; Bradley E. Patt

2007-01-01