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1

RADIATION DETECTORS  

Microsoft Academic Search

Three new and important lines of development in nuclear radiation ; detection and measurement are presented. Two of these developments, spark ; chambers and image-intensifier\\/ luminescent-chamber systems, enable pictures or ; other records of nuclear particle tracks to be obtained with a much higher degree ; of time resolution than is possible with existing techniques, e g., with cloud ;

W. Abson

1962-01-01

2

Adaptors for radiation detectors  

DOEpatents

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

Livesay, Ronald Jason

2014-04-22

3

Mossbauer spectrometer radiation detector  

NASA Technical Reports Server (NTRS)

A Mossbauer spectrometer with high efficiencies in both transmission and backscattering techniques is described. The device contains a sodium iodide crystal for detecting radiation caused by the Mossbauer effect, and two photomultipliers to collect the radiation detected by the crystal. When used in the transmission technique, the sample or scatterer is placed between the incident radiation source and the detector. When used in a backscattering technique, the detector is placed between the incident radiation source and the sample of scatterer such that the incident radiation will pass through a hole in the crystal and strike the sample. Diagrams of the instrument are provided.

Singh, J. J. (inventor)

1973-01-01

4

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

5

Amorphous silicon radiation detectors  

DOEpatents

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

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

1992-01-01

6

Amorphous silicon radiation detectors  

DOEpatents

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

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

1992-11-17

7

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

8

Semiconductor radiation detector  

DOEpatents

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

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

2002-01-01

9

Precision synchrotron radiation detectors  

SciTech Connect

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

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

1989-03-01

10

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

11

Radiation Hazard Detector  

NASA Technical Reports Server (NTRS)

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

1978-01-01

12

Radiation detectors as surveillance monitors  

Microsoft Academic Search

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

P. E. Fehlau; E. J. Dowdy

1981-01-01

13

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

14

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

15

Advanced Space Radiation Detector Technology Development  

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

16

Advanced Space Radiation Detector Technology Development  

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

17

Advanced Space Radiation Detector Technology Development  

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

18

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

19

Radiation detector spectrum simulator  

DOEpatents

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

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

1987-01-01

20

Advanced Radiation Detector Development  

SciTech Connect

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

The University of Michigan

1998-07-01

21

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

22

Gamma radiation detectors for safeguards applications  

Microsoft Academic Search

The IAEA uses extensively a variety of gamma radiation detectors to verify nuclear material. These detectors are part of standardized spectrometry systems: germanium detectors for High-Resolution Gamma Spectrometry (HRGS); Cadmium Zinc Telluride (CZT) detectors for Room Temperature Gamma Spectrometry (RTGS); and NaI(Tl) detectors for Low Resolution Gamma Spectrometry (LRGS). HRGS with high-purity Germanium (HpGe) detectors cooled by liquid nitrogen is

R. Carchon; M. Moeslinger; L. Bourva; C. Bass; M. Zendel

2007-01-01

23

InI nuclear radiation detectors  

Microsoft Academic Search

Semiconductor radiation detectors were fabricated on single crystal wafers on indium iodide and tested both as direct radiation detectors and as optical detectors coupled to a scintillator crystal. Indium iodide is shown to be a promising material for fabricating room-temperature photodetectors for use in scintillation spectroscopy due to its high resistivity, good charge transport properties, and high quantum efficiency in

M. R. Squillante; C. Zhou; J. Zhang; L. P. Moy; K. S. Shah

1992-01-01

24

Electromechanically cooled germanium radiation detector system  

Microsoft Academic Search

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

A. D. Lavietes; G. Joseph Mauger; E. H. Anderson

1999-01-01

25

49 CFR 173.310 - Exceptions for radiation detectors.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Exceptions for radiation detectors. 173.310 Section 173.310 ...Preparation and Packaging § 173.310 Exceptions for radiation detectors. Radiation detectors, radiation sensors, electron tube...

2013-10-01

26

49 CFR 173.310 - Exceptions for radiation detectors.  

Code of Federal Regulations, 2014 CFR

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

2014-10-01

27

49 CFR 173.310 - Exceptions for radiation detectors.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Exceptions for radiation detectors. 173.310 Section 173.310 ...Preparation and Packaging § 173.310 Exceptions for radiation detectors. Radiation detectors, radiation sensors, electron tube...

2012-10-01

28

49 CFR 173.310 - Exceptions for radiation detectors.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Exceptions for radiation detectors. 173.310 Section 173.310 ...Preparation and Packaging § 173.310 Exceptions for radiation detectors. Radiation detectors, radiation sensors, electron tube...

2011-10-01

29

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

30

Silicon radiation detectors - materials and applications  

Microsoft Academic Search

Silicon nuclear radiation detectors are available today in a large variety of sizes and types. This profusion has been made possible by the ever increasing quality and diameter silicon single crystals, new processing technologies and techniques, and innovative detector design. The salient characteristics of the four basic detector groups, diffused junction, ion implanted, surface barrier, and lithium drift are reviewed

J. T. Walton; E. E. Haller

1983-01-01

31

Silicon radiation detectors: Materials and applications  

Microsoft Academic Search

Silicon nuclear radiation detectors are available today in a large variety of sizes and types. This profusion was made possible by the ever increasing quality and diameter silicon single crystals, new processing technologies and techniques, and innovative detector design. The salient characteristics of the four basic detector groups, diffused junction, ion implanted, surface barrier, and lithium drift are reviewed along

J. T. Walton; E. E. Haller

1982-01-01

32

Testing of radiation detectors by IBIC imaging  

Microsoft Academic Search

The nuclear microprobe technique IBIC (Ion Beam Induced Charge) was used for tests of different radiation detectors. By using a 2–6 MeV proton microbeam with a current of less than 1000 protons per second, images and profiles of charge collection efficiency in radiation detectors can be produced. This application of the IBIC technique provides results that can be used to

M. JaksiC; I. Bogdanovi?; M. Bogovac; S. Fazini?; S. Galassini; K. Kova?evi?; C. Manfredotti; E. Vittone

1996-01-01

33

Metamaterials for Cherenkov Radiation Based Particle Detectors  

SciTech Connect

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

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

2009-01-22

34

Enhanced radiation detectors using luminescent materials  

DOEpatents

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

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

2001-01-01

35

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

36

Processing circuitry for single channel radiation detector  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

37

Gamma radiation detectors for safeguards applications  

NASA Astrophysics Data System (ADS)

The IAEA uses extensively a variety of gamma radiation detectors to verify nuclear material. These detectors are part of standardized spectrometry systems: germanium detectors for High-Resolution Gamma Spectrometry (HRGS); Cadmium Zinc Telluride (CZT) detectors for Room Temperature Gamma Spectrometry (RTGS); and NaI(Tl) detectors for Low Resolution Gamma Spectrometry (LRGS). HRGS with high-purity Germanium (HpGe) detectors cooled by liquid nitrogen is widely used in nuclear safeguards to verify the isotopic composition of plutonium or uranium in non-irradiated material. Alternative cooling systems have been evaluated and electrically cooled HpGe detectors show a potential added value, especially for unattended measurements. The spectrometric performance of CZT detectors, their robustness and simplicity are key to the successful verification of irradiated materials. Further development, such as limiting the charge trapping effects in CZT to provide improved sensitivity and energy resolution are discussed. NaI(Tl) detectors have many applications—specifically in hand-held radioisotope identification devices (RID) which are used to detect the presence of radioactive material where a lower resolution is sufficient, as they benefit from a generally higher sensitivity. The Agency is also continuously involved in the review and evaluation of new and emerging technologies in the field of radiation detection such as: Peltier-cooled CdTe detectors; semiconductor detectors operating at room temperature such as HgI 2 and GaAs; and, scintillator detectors using glass fibres or LaBr 3. A final conclusion, proposing recommendations for future action, is made.

Carchon, R.; Moeslinger, M.; Bourva, L.; Bass, C.; Zendel, M.

2007-08-01

38

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

39

Device for calibrating a radiation detector system  

DOEpatents

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

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

1994-12-27

40

Smart detectors for Monte Carlo radiative transfer  

E-print Network

Many optimization techniques have been invented to reduce the noise that is inherent in Monte Carlo radiative transfer simulations. As the typical detectors used in Monte Carlo simulations do not take into account all the information contained in the impacting photon packages, there is still room to optimize this detection process and the corresponding estimate of the surface brightness distributions. We want to investigate how all the information contained in the distribution of impacting photon packages can be optimally used to decrease the noise in the surface brightness distributions and hence to increase the efficiency of Monte Carlo radiative transfer simulations. We demonstrate that the estimate of the surface brightness distribution in a Monte Carlo radiative transfer simulation is similar to the estimate of the density distribution in an SPH simulation. Based on this similarity, a recipe is constructed for smart detectors that take full advantage of the exact location of the impact of the photon packages. Several types of smart detectors, each corresponding to a different smoothing kernel, are presented. We show that smart detectors, while preserving the same effective resolution, reduce the noise in the surface brightness distributions compared to the classical detectors. The most efficient smart detector realizes a noise reduction of about 10%, which corresponds to a reduction of the required number of photon packages (i.e. a reduction of the simulation run time) of 20%. As the practical implementation of the smart detectors is straightforward and the additional computational cost is completely negligible, we recommend the use of smart detectors in Monte Carlo radiative transfer simulations.

Maarten Baes

2008-09-11

41

Smart detectors for Monte Carlo radiative transfer  

NASA Astrophysics Data System (ADS)

Many optimization techniques have been invented to reduce the noise that is inherent in Monte Carlo radiative transfer simulations. As the typical detectors used in Monte Carlo simulations do not take into account all the information contained in the impacting photon packages, there is still room to optimize this detection process and the corresponding estimate of the surface brightness distributions. We want to investigate how all the information contained in the distribution of impacting photon packages can be optimally used to decrease the noise in the surface brightness distributions and hence to increase the efficiency of Monte Carlo radiative transfer simulations. We demonstrate that the estimate of the surface brightness distribution in a Monte Carlo radiative transfer simulation is similar to the estimate of the density distribution in a smoothed particle hydrodynamics simulation. Based on this similarity, a recipe is constructed for smart detectors that take full advantage of the exact location of the impact of the photon packages. Several types of smart detectors, each corresponding to a different smoothing kernel, are presented. We show that smart detectors, while preserving the same effective resolution, reduce the noise in the surface brightness distributions compared to the classical detectors. The most efficient smart detector realizes a noise reduction of about 10 per cent, which corresponds to a reduction of the required number of photon packages (i.e. a reduction of the simulation run time) of 20 per cent. As the practical implementation of the smart detectors is straightforward and the additional computational cost is completely negligible, we recommend the use of smart detectors in Monte Carlo radiative transfer simulations.

Baes, Maarten

2008-12-01

42

Thallium Bromide Nuclear Radiation Detector Development  

Microsoft Academic Search

Thallium bromide (TlBr) is a dense, high-Z, wide bandgap semiconductor that has potential as an efficient, compact, room temperature nuclear radiation detector. In this paper we report on our recent progress in TlBr nuclear detector development. In particular, improvements in material purification have led to an order of magnitude increase in the mobility-lifetime product of electrons, (mutau)e, to as high

Alexei V. Churilov; Guido Ciampi; Hadong Kim; Leonard J. Cirignano; William M. Higgins; Fred Olschner; Kanai S. Shah

2009-01-01

43

Thallium bromide nuclear radiation detector development  

Microsoft Academic Search

Thallium bromide (TlBr) is a dense, high-Z, wide band gap semiconductor that has potential as an efficient, compact, room temperature nuclear radiation detector. In this paper we report on our recent progress in TlBr nuclear detector development. In particular, improvements in material purification have led to an order of magnitude increase in the mobility-lifetime product of electrons, (??)e, to as

Alexei V. Churilov; Guido Ciampi; Hadong Kim; Leonard J. Cirignano; William M. Higgins; Fred Olschner; Kanai S. Shah

2008-01-01

44

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

45

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

46

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

47

Analytical model of the ferroelectric radiation detector  

Microsoft Academic Search

As part of the Defense Nuclear Agency project Jl1 AAXPX231 to study the ; behavior of the ferroelectric radiation detector, an analytical model of the ; energy balance within a ferroelectric crystal has been developed. This model ; relates ionic spacing and charges to macroscopic quantities such as the ; pyroelectric and piezoelectric coefficients. Although a highly simplified model, ;

J. T. Klopcic; D. L. Swanson

1973-01-01

48

Nuclear Radiation Induced Noise in Infrared Detectors  

Microsoft Academic Search

A model for calculating the rate and amplitude of gamma ionization events in infrared detectors is presented. Several simplifying approximations to the actual, complex physical situation are applied in the model, thereby allowing an exact analytical formulation of the problem. Experimental measurements of nuclear-radiation induced noise pulse-height distributions and event rates are compared to predictions made using the model. Comparisons

J. C. Pickel; M. D. Petroff

1975-01-01

49

Nuclear radiation induced noise in infrared detectors  

Microsoft Academic Search

A model for calculating the rate and amplitude of gamma ionization events in infrared detectors is presented. Several simplifying approximations to the actual, complex physical situation are applied in the model, thereby allowing an exact analytical formulation of the problem. Experimental measurements of nuclear-radiation induced noise pulse-height distributions and event rates are compared to predictions made using the model. Comparisons

J. C. Pickel; M. D. Petroff

1975-01-01

50

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

51

Workshop on detectors for synchrotron radiation  

SciTech Connect

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

Robinson, Arthur L.

2000-11-22

52

Compton scatter transition radiation detectors for ACCESS  

NASA Astrophysics Data System (ADS)

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

Case, Gary L.; Cherry, Michael L.

2004-01-01

53

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

54

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

55

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

56

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

57

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

58

A Silicon Transition Radiation Detector for space and accelerator applications  

Microsoft Academic Search

We have developed an unconventional Transition Radiation Detector (SiTRD) based on silicon strip detectors (SSDs) operating inside a magnetic field. In this way, the path of the radiating particle is deflected with respect to the transition radiation X-rays that convert in a detector region far away from the charged particle track. In this paper we will show the results of

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

2006-01-01

59

Position sensitivity in gallium arsenide radiation detectors  

SciTech Connect

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

Harper, R.; Hilko, R.A.

1994-12-31

60

Principles and new developments of semiconductor radiation detectors  

Microsoft Academic Search

The physics aspects of semiconductor radiation detectors are briefly reviewed. A comparison with other radiation detectors, in particular with wire chambers, shows the unique features of the advanced semiconductor detectors of high density, high ionisation density and the possibility of drift field shaping using space charges. Novel applications and device arrangements are discussed.

A. H. Walenta

1987-01-01

61

SILICON SURFACE-BARRIER RADIATION DETECTORS SOME DESIGNS AND APPLICATIONS  

Microsoft Academic Search

A wide range of semiconductor surface-barrier radiation detectors now ; being developed is described. The performance and electronic requirements of the ; detectors are discussed together with a general description of the techniques ; used in the preparation of the crystals and their subsequent encapsulation. The ; areas of the detectors range from a few mm² to a multiple detector

P. G. Salmon; F. L. Allsworth

1963-01-01

62

Resonant tuning fork detector for THz radiation.  

PubMed

THz-sensing is an emerging technology that would be advantageous for a variety of applications in industry, biology, biochemistry and security, if small and convenient to use sources and detectors would be readily available. However, most of them are bulky, complicate to operate, and need cryogenic cooling. Here we present a new detection scheme that is versatile enough to detect electro-magnetic radiation within the whole spectrum, can be easily applied to the THz-range, and operates at room temperature. The mechanism is based on the resonant excitation of a quartz tuning fork. PMID:19654815

Willer, Ulrike; Pohlkötter, Andreas; Schade, Wolfgang; Xu, Jihua; Losco, Tonia; Green, Richard P; Tredicucci, Alessandro; Beere, Harvey E; Ritchie, David A

2009-08-01

63

Monte Carlo methods for design and analysis of radiation detectors  

Microsoft Academic Search

An overview of Monte Carlo as a practical method for designing and analyzing radiation detectors is provided. The emphasis is on detectors for radiation that is either directly or indirectly ionizing. This overview paper reviews some of the fundamental aspects of Monte Carlo, briefly addresses simulation of radiation transport by the Monte Carlo method, discusses the differences between direct and

William L. Dunn; J. Kenneth Shultis

2009-01-01

64

Investigation of basic characteristics of synthetic diamond radiation detectors  

Microsoft Academic Search

Diamonds have attractive properties for use as radiation detectors. Recent advances in diamond fabrication techniques have made it possible to produce almost perfect single crystal materials that have electrical properties suitable for radiation detectors. We therefore developed detectors made of high-purity synthetic IIa diamonds grown by a high-pressure, high-temperature method and investigated their basic properties. These detectors have Schottky and

Toshisuke Kashiwagi; Kinya Hibino; Hisashi Kitamura; Kunishiro Mori; Shoji Okuno; Takeshi Takashima; Yukio Uchihori; Kaori Yajima; Mamoru Yokota; Kenji Yoshida

2006-01-01

65

NUCLEAR RADIATION DETECTORS. Review Report No. 5  

Microsoft Academic Search

The book discusses several types of detectors, including ionization ; detectors, scintillation counters, Cherenkov counters, semiconductor devices, and ; crystalline detectors. Other types of detectors which are not discussed because ; of limited application include Wilson and bubble chambers. photographic ; emulsions, and chemical dosimeters. The principles of operation and proper use ; of the detectors are presented. The latest

Kazimierski

1962-01-01

66

The HERMES dual-radiator RICH detector  

NASA Astrophysics Data System (ADS)

The HERMES experiment emphasizes measurements of semi-inclusive deep-inelastic scattering. Most of the hadrons produced lie between 2 and 10 GeV, a region in which it had not previously been feasible to separate pions, kaons, and protons with standard particle identification (PID) techniques. The recent development of new clear, large, homogeneous and hydrophobic silica aerogel material with a low index of refraction offered the means to apply RICH PID techniques to this difficult momentum region. The HERMES instrument uses two radiators, C 4F 10, a heavy fluorocarbon gas, and a wall of silica aerogel tiles. A lightweight spherical mirror constructed using a newly perfected technique to make resin-coated carbon-fiber surfaces of optical quality provides optical focusing on a photon detector consisting of 1934 photomultiplier tubes (PMT) for each detector half. The PMT array is held in a soft steel matrix to provide shielding against the residual field of the main spectrometer magnet. Ring reconstruction is accomplished with pattern recognition techniques based on a combination of inverse and direct ray tracing.

Jackson, H. E.

2003-04-01

67

A hybrid radiation detector based on a plasma display panel  

Microsoft Academic Search

Recently, large-area image detectors have been investigated for X-ray imaging in medical diagnostic and other applications. In this paper, a new type of radiation detector is described, based on the integration of a photoconductor into a plasma display panel (PDP). This device, called a hybrid PDP detector, should be quite inexpensive, because it can directly leverage off the fabrication and

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

2009-01-01

68

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

69

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

70

Transition radiation detectors for underground and space laboratories  

Microsoft Academic Search

The performances of transition radiation detectors are reviewed. We discuss the applications of these devices to measure the energy of cosmic rays muons in underground laboratories and present the first results from prototypes operating in the TeV energy region. Another interesting application of transition radiation detectors is the discrimination of positron from protons in the outer space to search for

R. Bellotti; F. Cafagna; M. Calicchio; G. de Cataldo; C. de Marzo; O. Erriquez; C. Favuzzi; P. Fusco; N. Giglietto; B. Marangelli; E. Nappi; A. Rainó; P. Spinelli

1991-01-01

71

Progress in the Development of Plasma Panel Radiation Detectors  

E-print Network

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

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

2010-12-30

72

Radiation tolerance of the CMS forward pixel detector  

NASA Astrophysics Data System (ADS)

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

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

2009-03-01

73

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

74

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

75

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

76

Radiation environment and shielding for a high luminosity collider detector  

SciTech Connect

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

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

1995-12-01

77

Large dynamic range radiation detector and methods thereof  

DOEpatents

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

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

2012-02-14

78

Silicon radiation detector fabricated in a standard IC process  

Microsoft Academic Search

The authors present a silicon radiation detector for nuclear radiation, fabricated in a standard IC process, in which the generated charge carriers are collected by means of diffusion. A model is derived and experiments with optical and nuclear radiation are presented. Ionizing particles can be detected with a reasonable internal efficiency (65%) and response time (<10 ?s), and the spatial

S. E. Wouters; T. Otaredian; E. M. Schooneveld

1991-01-01

79

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

80

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

81

Implementation of a conditioning circuit for radiation detectors  

Microsoft Academic Search

In this paper are presented the results achieved in the implementation of a measurement and conditioning circuit for solid-state radiation detectors used in measurement\\/monitoring of neutrons\\/gamma radiation fluxes generated by nuclear plants or other radioactive sources. In comparison with other implementations, the proposed detector has the advantage of a compact realization and an improved sensitivity. Also, the circuit is designed

Ioan Lita; Daniel Alexandru Visan

2011-01-01

82

Development of a high-sensitivity radiation detector for chromatography  

Microsoft Academic Search

Radionuclide techniques will be increasingly important for the development of biofuels, since they can both uniquely characterize metabolic pathways and image large model systems. We are investigating the application of nuclear medical imaging tools and techniques to biofuel development, using high-sensitivity chromatographic radiation detectors and compounds radiolabeled with short-lived, cyclotron-produced, positron-emitting isotopes (e.g., 11C). The application of high-sensitivity radiation detectors

J. S. Huber; S. M. Hanrahan; W. W. Moses; S. E. Derenzo; B. W. Reutter; J. P. O'Neil; G. T. Gullberg

2009-01-01

83

Determining the Martian Radiation Environment — The Radiation Assessment Detector (RAD) on Mars Science Laboratory (MSL)  

NASA Astrophysics Data System (ADS)

The Radiation Assessment Detector (RAD) onboard the Mars Science Laboratory (MSL) is performing radiation measurements en route to Mars. On Mars it will measure the broad particle spectrum and determine the dose and dose rate on the martian surface.

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

2012-03-01

84

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

85

Proton-induced radiation damage in germanium detectors  

SciTech Connect

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

Bruckner, J.; Korfer, M.; Wanke, H. (Max-Planck-Institut fuer Chemie (Otto-Hahn-Institut), Mainz (Germany)); Schroeder, A.N.F. (Univ. zu Koln, D-5000 Koln 41 (DE)); Figes, D.; Dragovitsch, P. (Inst. fur Kernphysik, KFA Julich, D-5170 Julich (DE)); Englert, P.A.J. (San Jose State Univ., CA (United States)); Starr, R.; Trombka, J.I. (National Aeronautics and Space Administration, Greenbelt, MD (United States). Goddard Space Flight Center); Taylor, I. (Princeton Gamma-Tech, Princeton, NJ (US)); Drake, D.M.; Shunk, E.R. (Los Alamos National Lab., NM (United States))

1991-04-01

86

Proton-induced radiation damage in germanium detectors  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

87

Using cumulants and spectra to model nuclear radiation detectors  

Microsoft Academic Search

A general mathematical methodology is presented to model a nuclear radiation detector. This is accomplished by using a proposed generalization of Campbell's theorem, which employs nth-order cumulants and spectra analysis and a vector of random parameters to describe the current pulses. This allows a more elaborate, higher order statistical characterization of the radiation detection process, as compared to the usual

Eduardo Winston Pontes; Ademar Ferreira

2006-01-01

88

Advances in gas avalanche radiation detectors for biomedical applications  

Microsoft Academic Search

Gas avalanche detectors are instruments of choice for radiation detection and localization in numerous fields of basic and applied research. Recent advances in detection techniques, involving multiplication and detection of single or a few charges deposited in gas media, or emitted from solid converters into gas, are described. The properties of radiation converters and associated advanced gas multipliers are discussed,

A. Breskin

2000-01-01

89

Nuclear radiation-warning detector that measures impedance  

DOEpatents

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

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

2013-06-04

90

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

Microsoft Academic Search

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

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

2011-01-01

91

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

Microsoft Academic Search

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

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

2004-01-01

92

Cryogenic Si detectors for ultra radiation hardness in SLHC environment  

NASA Astrophysics Data System (ADS)

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

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

2007-09-01

93

Proton-induced radiation damage in germanium detectors  

Microsoft Academic Search

High-purity germanium (HPGe) detectors will be used in future space missions for gamma-ray measurements and will be subject to interactions with energetic particles. To simulate this process, several large-volume n-type HPGe detectors were incrementally exposed to a particle fluence of up to 108 protons cm-2 (proton energy: 1.5 GeV) at different operating temperatures (90 to 120 K) to induce radiation

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

1991-01-01

94

Three-axis asymmetric radiation detector system  

DOEpatents

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

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

2000-01-01

95

Radiation detectors as surveillance monitors for IAEA safeguards  

SciTech Connect

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

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

1980-10-01

96

Radiation detector for use in nuclear reactors  

SciTech Connect

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

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

1981-09-08

97

Effect of temperature on silicon PIN photodiode radiation detectors  

NASA Astrophysics Data System (ADS)

One of the noise sources of a semiconductor radiation detector is thermal noise, which degrades the performance, such as the energy resolution and unexpected random pulse signals. In this study, PIN photodiode radiation detectors, with different active areas were designed and fabricated for an experimental comparison of the energy resolutions for different temperatures and capacitances by using a Ba-133 calibration gamma-ray source. The experimental temperature was approximately in the range from -7 to 24 °C and was controlled by using a peltier device. The design considerations and the electrical characteristics, such as the I-V and the C-V characteristics, are also addressed.

Kim, Han Soo; Jeong, Manhee; Kim, Young Soo; Ha, Jang Ho; Cho, Seong Yeon

2014-03-01

98

(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

99

Radiation damage effects in CZT drift strip detectors  

NASA Astrophysics Data System (ADS)

At DSRI, in collaboration with the cyclotron facility at Copenhagen University Hospital, we have performed a study of radiation effects exposing a 2.7 mm thick CZT drift strip detector to 30 MeV protons. The detector characteristics were evaluated after exposure to a number of dose loads in the range from 2*108 to 60*108 p+/cm2. Even for the highest dose loads, which had a dramatic effect on the spectroscopic performance, we were able to recover the detectors after an appropriate annealing procedure. The radiation damage was studied as function of depth inside the detector material. A numerical model that emulates the physical processes of the charge transport in the CZT detector was used to derive the charge trapping parameter , ??e (the product of charge mobility and trapping time) as function of dose. The analysis showed that the electron trapping increased proportional with the proton dose. The radiation contribution to the electron trapping was found to obey the following relation: (??e)-1rad =(2.5±0.2)*10-7*? (V/cm2) with the proton fluence, ? in p+/cm2. The trapping depth dependence, however, did not agree well the damage profile calculated using the standard Monte Carlo simulations, TRIM for the proton induced radiation effects. The present results suggest that proton induced nuclear reactions contribute significantly to the radiation damage. Further work will elaborate on these effects. The detector energy resolution was investigated as function of proton dose. It was found that the observed degradation is well explained by the decrease of ??e when the fluctuations of the electron path length are taken into account. The proton irradiation produced In meta stable isotopes in the CZT material. Their decay and production yield as function of depth were analyzed.

Kuvvetli, Irfan; Budtz-Joergensen, Carl; Korsbech, Uffe; Jensen, H. J.

2003-03-01

100

Applications of a-Si:H radiation detectors  

SciTech Connect

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

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

1989-07-01

101

Synthetic diamonds as in vivo radiation detectors  

Microsoft Academic Search

Synthetic diamonds with controlled amounts of impurity atoms can be manufactured so that, as thermoluminescent dosimeters, they can be made to have sensitivities at least as good as presently available commercial thermoluminescent dosimeters. They also exhibit, for radiations normally found in therapy situations, a linearity of response that extends from less than 0.01 Gy (1 rad) to over 10 Gy

Tom L. Nam; R. J. Keddy; R. C. Burns

1987-01-01

102

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

103

Development of a High-Sensitivity Radiation Detector for Chromatography  

Microsoft Academic Search

We describe a radiotracer imaging system for mea- suring the biochemical production rates of organic compounds from animals or plants. It uses a high performance liquid chro- matography (HPLC) column to separate the compounds and a parallel-plane radiation detector to measure the disintegrations from each compound over a period of time. Because the mea- surement time is much longer than

Jennifer S. Huber; Stephen M. Hanrahan; William W. Moses; Steve E. Derenzo; Bryan W. Reutter; James P. O'Neil; Grant T. Gullberg

2011-01-01

104

Fabrication techniques for reverse electrode coaxial germanium nuclear radiation detectors  

Microsoft Academic Search

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

W. L. Hansen; E. E. Haller

1980-01-01

105

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

106

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

107

A radiation detector design mitigating problems related to sawed edges  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

108

Three-dimensional architecture for solid state radiation detectors  

DOEpatents

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

Parker, Sherwood (Berkeley, CA)

1999-01-01

109

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

110

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

111

Background radiation studies for future, above ground antineutrino detectors  

NASA Astrophysics Data System (ADS)

We will describe an assembly of radiation detectors that quantifies the gamma, muon, and fast and thermal neutron fluxes present at potential above ground antineutrino detector sites. Antineutrino detectors show great promise for reactor safeguards applications, due to their ability to monitor thermal power and/or fissile content. One of the major technical challenges that this safeguard application faces is the ability to distinguish signals from antineutrinos originating in a reactor core from noise due to background created by terrestrial and cosmogenic radiation. To date, antineutrino experiments have increased the signal to noise in their detectors by surrounding the experiments with significant shielding and placing them underground. For the safeguards agency, this is less than optimal, as it increases the overall size of the device and limits the range of possible deployment locations. Placing reactor monitoring antineutrino detectors at, or near, the surface would greatly increase the range of possible deployment locations. In order to investigate designs that would allow this, we must understand the backgrounds found above ground that can mimic the antineutrino signal so that these can be easily identified, separated, and subtracted rather than shielded. The design, construction, calibration, and results from the deployment of this background measurement system at a variety of sites will be presented.

Sadler, L. E.; Bernstein, A.; Bowden, N. S.; Dazeley, S.; Lund, J.; Mrowka, S.; Reyna, D.

2008-11-01

112

Design of a wire imaging synchrotron radiation detector  

SciTech Connect

This paper documents the design of a detector invented to measure the positions of synchrotron radiation beams for the precision energy spectrometers of the Stanford Linear Collider (SLC). The energy measurements involve the determination, on a pulse-by-pulse basis, of the separation of pairs of intense beams of synchrotron photons in the MeV energy range. The detector intercepts the beams with arrays of fine wires. The ejection of Compton recoil electrons results in charges being developed in the wires, thus enabling a determination of beam positions. 10 refs., 4 figs.

Kent, J.; Gomez-Cadenas, J.J.; Hogan, A.; King, M.; Rowe, W.; Watson, S.; Von Zanthier, C. (California Univ., Santa Cruz, CA (USA)); Briggs, D.D. (Stanford Linear Accelerator Center, Menlo Park, CA (USA)); Levi, M. (Lawrence Berkeley Lab., CA (USA))

1990-01-01

113

Optimization of efficiency and response time of diffusion-based nuclear radiation detectors  

Microsoft Academic Search

The charge collection process in a diffusion-based silicon nuclear radiation detector was investigated by illuminating the detector at the backside with optical radiation. The results are compared to calculations and show good agreement. The collection mechanism is characterized, and the detector response to nuclear radiation and its optimum with respect to efficiency and response time are calculated. Efficiency and response

S. E. Wouters; T. Otaredian; E. M. Schooneveld

1991-01-01

114

Plastic scintillator-based radiation detector for mobile radiation detection system against nuclear/radiological terrorism  

NASA Astrophysics Data System (ADS)

Illicit trafficking of nuclear or radioactive materials has become a serious world wide problem. Due to operational constraints of radiation detection system for such nuclear security application, a radiation detector with large effective area is needed to maximize its sensitivity. This paper suggests a new method of using plastic scintillation detector as a cost-effective mobile radiation detection system. Monte Carlo simulation code, MCNPX, has been used to analyze spectral distribution available from the plastic detector and to derive algorithmic process with a view to discriminating targeted sources from ambient background radiation. Theoretical results in present work showed that the targeted sources which might be used for nuclear/radiological terrorism could be discriminated from Nationally Occurring Radioactive Material (NORM) or background.

Kwak, Sung-Woo; Yoo, Ho-Sik; Jang, Sung Soon; Kim, Jung Soo; Yoon, Wan-Ki; Jun, In Sub; Kim, Kwang Hyun

2009-06-01

115

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

SciTech Connect

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

Rykovanov, S. G.; Chen, M.; Geddes, C. G. R.; Schroeder, C. B.; Esarey, E.; Leemans, W. P. [Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley CA 94720 (United States)

2012-12-21

116

Radiation tests of the silicon drift detectors for LOFT  

NASA Astrophysics Data System (ADS)

During the three years long assessment phase of the LOFT mission, candidate to the M3 launch opportunity of the ESA Cosmic Vision programme, we estimated and measured the radiation damage of the silicon drift detectors (SDDs) of the satellite instrumentation. In particular, we irradiated the detectors with protons (of 0.8 and 11 MeV energy) to study the increment of leakage current and the variation of the charge collection efficiency produced by the displacement damage, and we "bombarded" the detectors with hypervelocity dust grains to measure the effect of the debris impacts. In this paper we describe the measurements and discuss the results in the context of the LOFT mission.

Del Monte, E.; Azzarello, P.; Bozzo, E.; Bugiel, S.; Diebold, S.; Evangelista, Y.; Kendziorra, E.; Muleri, F.; Perinati, E.; Rachevski, A.; Zampa, G.; Zampa, N.; Feroci, M.; Pohl, M.; Santangelo, A.; Vacchi, A.

2014-07-01

117

Modeling radiation loads to detectors in a SNAP mission  

SciTech Connect

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

Nikolai V. Mokhov et al.

2004-05-12

118

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

119

Synthetic diamonds as active detectors of ionising radiation  

Microsoft Academic Search

Synthetic diamond crystals produced by the HPHT (high pressure high temperature) method at the Institute of Mineralogy and Petrography, Novosibirsk, Russia were tested as active detectors of ionising radiation (in current mode). A synthetic diamond crystal was selected, fitted with electrical contacts, mounted in a holder built of A-150 conducting plastic and tested in external fields of 320 kV X-rays

B. Marczewska; T. Nowak; P. Olko; W. Gajewski; Yu. Pal'yanov; I. Kupriyanov; M. P. R. Waligórski

2004-01-01

120

Modeling and characterization of polycrystalline mercuric iodide radiation detectors  

Microsoft Academic Search

The ability of Mercuric Iodide (HgI2) to function as a highly efficient radiation detector at room temperature has generated great interest and has triggered further studies on this difficult material. This property is expected to enable significant enhancements to a far-ranging variety of applications and systems. HgI2 devices have shown superior performance at room temperature compared to elemental Si or

Unmesh Khadilkar

2003-01-01

121

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

122

Radiation tests for a single-GEM-loaded gaseous detector  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

123

Distinguishing Neutrons and Gammas with MSL's Radiation Assessment Detector (RAD)  

NASA Astrophysics Data System (ADS)

The radiation environment on the Martian surface is a complex mixture of charged primary and secondary radiation and of neutral secondary radiation. This neutral component amounts to a significant fraction of the surface radiation field and consists of neutrons and gamma rays. The neutron component is especially important from a radiation protection point of view, but is experimentally difficult to distinguish from the gamma rays. The Radiation Assessment Detector (RAD) on Mars Science Laboratory's (MSL's) rover Curiosity measures both neutrons and gammas. It consists of a compact arrangement of a dense, more gamma-sensitive CsI sctintillator, and a high-proton-content plastic scintillator, which in turn is more sensitive to neutrons. Using sophisticated inversion techniques, the RAD measurements can be inverted to provide reliable estimates for the neutron and gamma spectra on Mars. In this work we will discuss the status of the inversion techniques and calibration data, and relate them with predictions for the neutral component of the Martian surface radiation field.

Guo, J.; Hassler, D.; Wimmer-Schweingruber, R. F.; Zeitlin, C.; Boettcher, S.; Martin, C.; Brinza, D.; Koehler, J.; Böhm, E.; Kharytonov, A.; Ehresmann, B.

2012-12-01

124

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

125

Calculating the Responses of Self-Powered Radiation Detectors.  

NASA Astrophysics Data System (ADS)

Available from UMI in association with The British Library. The aim of this research is to review and develop the theoretical understanding of the responses of Self -Powered Radiation Detectors (SPDs) in Pressurized Water Reactors (PWRs). Two very different models are considered. A simple analytic model of the responses of SPDs to neutrons and gamma radiation is presented. It is a development of the work of several previous authors and has been incorporated into a computer program (called GENSPD), the predictions of which have been compared with experimental and theoretical results reported in the literature. Generally, the comparisons show reasonable consistency; where there is poor agreement explanations have been sought and presented. Two major limitations of analytic models have been identified; neglect of current generation in insulators and over-simplified electron transport treatments. Both of these are developed in the current work. A second model based on the Explicit Representation of Radiation Sources and Transport (ERRST) is presented and evaluated for several SPDs in a PWR at beginning of life. The model incorporates simulation of the production and subsequent transport of neutrons, gamma rays and electrons, both internal and external to the detector. Neutron fluxes and fuel power ratings have been evaluated with core physics calculations. Neutron interaction rates in assembly and detector materials have been evaluated in lattice calculations employing deterministic transport and diffusion methods. The transport of the reactor gamma radiation has been calculated with Monte Carlo, adjusted diffusion and point-kernel methods. The electron flux associated with the reactor gamma field as well as the internal charge deposition effects of the transport of photons and electrons have been calculated with coupled Monte Carlo calculations of photon and electron transport. The predicted response of a SPD is evaluated as the sum of contributions from individual response mechanisms.

Thornton, D. A.

126

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

127

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

128

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

129

Intrinsic Radiation in Lutetium Based PET Detector: Advantages and Disadvantages  

E-print Network

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

Wei, Qingyang

2015-01-01

130

Epitaxial gallium arsenide for nuclear radiation detector applications  

NASA Astrophysics Data System (ADS)

Radiation detectors consisting of MBE-, LPE-, and MOCVD-grown gallium arsenide layers were fabricated by employing standard photolithography techniques. The active region of the devices varied between 5 and 60 ?m thickness. Hall and CV measurements confirm the high quality of the material with unintended residual doping densities of the order 10 14/ cm3 and mobilities typical for GaAs. Dark current densities as low as j D = 0.2..2.0 ?A/ cm 2 were achieved for all devices. The energy resolution (FWHM) at room temperature for 60 keV ?-photons was 1.8 keV, while for 5.8 MeV?-particles ( 244Cm ) an energy resolution of 18.3 keV (FWHM) has been determined. The detectors exhibit a charge collection efficiency of approximately 100% within the experimental error.

Lauter, J.; Bauser, E.; Förster, A.; Hardtdegen, H.; Hollfelder, M.; Lüth, H.; Protic, D.; Zehender, S.

1995-11-01

131

The use of nuclear track detectors as an environmental solar ultraviolet radiation dosimeter  

Microsoft Academic Search

Investigation of using CR-39 nuclear track detectors as solar ultraviolet radiation (SUVR) dosimeter was studied. The nuclear track detectors were irradiated with Cf-252 (alpha and fission fragments) before exposure to sun light. The exposure of nuclear track detectors to SUVR were carried out under two different conditions (i) the detector was mounted on a solar tracker mechanism which always rotate

F. Abu-Jarad; M. El Hadidy; M. I. Al-Jarallah

1997-01-01

132

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

133

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

PubMed

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 approximately 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. PMID:15861830

Kück, Stefan; Brandt, Friedhelm; Taddeo, Mario

2005-04-20

134

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

135

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

136

Response of personal radiation detectors to simulated criticality accident pulses  

SciTech Connect

Personal radiation detection instruments (PRDIs) are often used to augment the protection provided by the installed criticality accident alarm system (CAAS). ANSI/ANS-8.3-1997 provides examples of situations when PRDIs could be used, including {hor{underscore}ellipsis}alarm system maintenance or testing, evacuation drills, activities in areas not normally occupied by personnel, or other special operations. These instruments were designed for use in radiological control applications. Consequently, documented performance capabilities under conditions typical of the initial pulse from a criticality accident are not readily available. This paper describes testing performed to demonstrate the capability of the PRDIs to respond to radiation pulses similar to that which would be expected to occur in the event of a criticality accident. Detector responses for low-power, oscillating, or slow excursions were either available from manufacturing data or bounded by the initial pulse.

Beard, K.S.; Smith, J.A.; Worley, C.A.

1999-07-01

137

Silicon diode radiation hardening for high energy physics detectors  

NASA Astrophysics Data System (ADS)

We summarize in a general review all the studies performed by our group in the last years in the field of radiation hardening of silicon detectors for High Energy Physics experiments. Test structures (silicon p-i-n diodes) were irradiated by 16 MeV, 27 MeV, 34 MeV and 24 GeV protons, and by fast neutrons from a nuclear reactor and from the 9Be(d,n) 10B nuclear reaction. We will show that after proton irradiation the substrate oxygenation mitigates the depletion voltage increase rate ?, which nevertheless presents a wide range of values if standard and oxygenated devices processed by different manufacturers are considered, pointing out that besides oxygenation, processing affects the diode radiation hardness in the case of proton irradiation. After neutron irradiation though the oxygen mitigating effect is strongly suppressed, nonetheless the ? dependence on the particular process can be important.

Rando, R.; Candelori, A.; Bisello, D.; Kaminski, A.; Litovchenko, A.; Pantano, D.; Stavitski, I.; Wyss, J.

2003-11-01

138

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

139

Nuclear Track Detectors for Environmental Studies and Radiation Monitoring  

E-print Network

Several improvements were made for Nuclear Track Detectors (NTDs) used for environmental studies and for particle searches. A new method was used to determine the bulk etch rate of CR39 and Makrofol NTDs. It is based on the simultaneous measurement of the diameter and of the height of etch-pit cones caused by relativistic heavy ions (158 A GeV Pb(82+) and In(49+) ions) and their fragments. The use of alcohol in the etching solution improves the surface quality of NTDs and it raises their thresholds. The detectors were used for the determination of nuclear fragmentation cross sections of Iron and Silicon ions of 1.0 and 0.41 GeV/nucleon. These measurements are important for the determination of doses in hadron therapy and for doses received by astronauts. The detectors were also used in the search of massive particles in the cosmic radiation, for the determination of the mass spectrum of cosmic rays and for the evaluation of Po(210) alpha decay and of natural radon concentrations.

Manzoor, S; Cozzi, M; Errico, M; Giacomelli, G; Giorgini, M; Kumar, A; Margiotta, A; Medinaceli, E; Patrizii, L; Popa, V; Qureshi, I E; Togo, V

2007-01-01

140

Coupled Deterministic\\/Monte Carlo Simulation of Radiation Transport and Detector Response  

Microsoft Academic Search

The analysis of radiation sensor systems used to detect and identify nuclear and radiological weapons materials requires detailed radiation transport calculations. Two basic steps are required to solve radiation detection scenario analysis (RDSA) problems. First, the radiation field produced by the source must be calculated. Second, the response that the radiation field produces in a detector must be determined. RDSA

Christopher J. Gesh; George H. Meriwether; Richard T. Pagh; Leon E. Smith

2005-01-01

141

Methodology for Assessing Radiation Detectors Used by Emergency Responders  

SciTech Connect

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

Piotr Wasiolek; April Simpson

2008-03-01

142

A method of providing directionality for ionising radiation detectors — RadICAL  

NASA Astrophysics Data System (ADS)

A novel method for providing directionality for radiation detection is presented. The idea is based upon the fact that detector response depends upon two properties of the active component in the detector: the radiation pathlength and the area presented to a particle flux. Thus a rotating slab of detector gives a characteristic temporal response that can be used to identify the direction of the photon flux. A model of the detector system is used to design and build a detector which is then evaluated. It is shown that a rotating detector of this nature can produce a characteristic curve which can be used to determine the location of a single stationary point source.

Randall, G. L.; Iglesis, E.; Wong, H. F.; Speller, R. S.

2014-10-01

143

Glow discharge detector for terahertz and millimeter wave radiation detection and imaging  

NASA Astrophysics Data System (ADS)

Glow discharge plasma, deriving from direct current gas breakdown, was investigated in order to realize an inexpensive THz room temperature detector. Preliminary results for THz radiation show that glow discharge indicator lamps as room temperature detectors yield good responsivity and NEP. Development of a Focal Plane Array (FPA) using such devices as detectors is advantageous since the costs of glow discharge detector is around 0.2-0.5 per lamp, and the FPA images will be diffraction limited. The detection mechanism of the glow discharge detector was found to be enhanced diffusion current which causes decrease of glow discharge detector bias current when exposed to THz radiation.

Abromovich, A.; Kopeika, N. S.; Rozban, D.

2007-10-01

144

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

NASA Astrophysics Data System (ADS)

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

Yagi, Naoto; Yamamoto, Masaki; Uesugi, Kentaro; Inoue, Katsuaki

2004-05-01

145

Materials for thermoluminescent dose detectors and photon radiation energy detectors intended for intercomparison procedures of radiation therapy units.  

PubMed

Composite thermoluminescent (TL) materials characterized by different TL sensitivity to energy of photon radiation, namely, double-component mixtures of finely dispersed ingredients: thermoluminescent phosphor (LiF or CaSO4:Dy) and nonluminescent material (salts with various Zeff values) have been described. The TL sensitivity of such TL composites was demonstrated to depend upon Zeff values inherent to separate components and upon their concentration ratio in the mixture. Within the range of x-ray energy values from 10 to 120 keV, the LiF-based materials containing Li2CO3 as nonluminescent material were dosimetrically equivalent to soft tissues. The availability of powder-like TLD materials containing 65% LiF + 35% Li2CO3 can definitely serve the basis for extending the application area for the well-known procedure adopted by IAEA/WHO for comparative testing of x-ray therapy units with HVL < 0.5 mm Cu and for starting the intercomparison of units intended for superficial x-ray therapy. The use of the dose detectors based on TLD of 35% LiF + 65% Li2CO3 composition in orthovoltage x-ray therapy units excludes the necessity for introducing corrections for the dependence of detector's readings on energy levels. LiF- and CaSO4:Dy-based TL materials containing PbSO4 as a nonluminescent material are, by a factor of 10, more sensitive to energy variations than other known thermoluminescent phosphors. With the application of TLD based on above materials into two-detector systems intended for determining Eeff values of x-ray radiation, the ambiguity of readings in low-energy region has been eliminated, whereas the range of measurement appeared to be significantly expanded. PMID:7891631

Kalmykov, L Z

1994-11-01

146

Detection of neutral particle radiation with the Mars Science Laboratory (MSL) Radiation Assessment Detector (RAD)  

NASA Astrophysics Data System (ADS)

RAD, the Radiation Assessment Detector on NASA's Mars Science Laboratory (MSL) rover mission is designed to detect a wide range of different particle species at energies up to 100 MeV/nuc. We present the beam testing results for the flight units of the RAD Sensor Head unit (RSH). Neutral particle response, anti-coincidence efficiency as well as behaviour for relativistic high-Z (up to iron) particles will be shown. Additionally, we present the response of our RSH GEANT4 model for the expected (simulated) Mars surface radiation environment.

Kortmann, O.; Martin, C.; Boehm, E.; Boettcher, S.; Wimmer-Schweingruber, R. F.; Burmeister, S.; Ehresmann, B.; Hassler, D. M.; Zeitlin, C.; Posner, A.; Rafkin, S.; Weigle, E.; Neal, K.; Reitz, G.

2008-12-01

147

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

148

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

149

BOBCAT Personal Radiation Detector Field Test and Evaluation Campaign  

SciTech Connect

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

Chris Hodge

2008-03-01

150

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

DOEpatents

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

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

2002-01-01

151

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

152

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

153

Combined performance tests before installation of the ATLAS Semiconductor and Transition Radiation Tracking Detectors  

Microsoft Academic Search

The ATLAS (A Toroidal LHC ApparatuS) Inner Detector provides charged particle tracking in the centre of the ATLAS experiment at the Large Hadron Collider (LHC). The Inner Detector consists of three subdetectors: the Pixel Detector, the Semiconductor Tracker (SCT), and the Transition Radiation Tracker (TRT). This paper summarizes the tests that were carried out at the final stage of SCT+TRT

E Abat; A Abdesselam; T N Addy; T P A Åkesson; P P Allport; L Andricek; F Anghinolfi; R Apsimon; E Arik; M Arik; N Austin; O K Baker; E Banas; A Bangert; G Barbier; S Baron; A J Barr; S Basiladze; L E Batchelor; R L Bates; J R Batley; M Battistin; G A Beck; A Beddall; P J Bell; W H Bell; A Belymam; D P Benjamin; J Bernabeu; H Bertelsen; S Bethke; A Bingul; A Bitadze; J P Bizzell; J Blocki; A Bocci; M Bochenek; J Bohm; V G Bondarenko; P Bonneau; C N Booth; O Brandt; F M Brochu; Z Broklova; J Broz; P A Bruckman de Renstrom; S Burdin; C M Buttar; M Capeáns Garrido; L Cardiel Sas; C Carpentieri; A A Carter; J R Carter; A Catinaccio; S A Cetin; M Chamizo llatas; D G Charlton; A Cheplakov; S Chouridou; M L Chu; V Cindro; A Ciocio; J V Civera; A Clark; A P Colijn; T Cornelissen; M J Costa; D Costanzo; J Cox; P Cwetanski; W Dabrowski; J Dalmau; M Dam; K M Danielsen; H Danielsson; S DAuria; I Dawson; P de Jong; M D Dehchar; B Demirkoz; P Dervan; B Di Girolamo; S Diez Cornell; F Dittus; S D Dixon; E Dobson; O B Dogan; Z Dolezal; B A Dolgoshein; M Donega; M DOnofrio; T Donszelmann; O Dorholt; J D Dowell; Z Drasal; N Dressnandt; C Driouchi; R Duxfield; M Dwuznik; W L Ebenstein; S Eckert; P Eerola; U Egede; K Egorov; L M Eklund; M Elsing; R Ely; V Eremin; C Escobar; H Evans; P Farthouat; D Fasching; O L Fedin; L Feld; D Ferguson; P Ferrari; D Ferrere; L Fiorini; J Fopma; A J Fowler; H Fox; R S French; D Froidevaux; J A Frost; J Fuster; S Gadomski; P Gagnon; B J Gallop; F C Gannaway; C Garcia; J E Garcia Navarro; I L Gavrilenko; C Gay; N Ghodbane; M D Gibson; S M Gibson; K G Gnanvo; J Godlewski; T Göttfert; S Gonzalez; S Gonzalez-Sevilla; M J Goodrick; A Gorišek; E Gornicki; M Goulette; Y Grishkevich; J Grognuz; J Grosse-Knetter; C Haber; R Härtel; Z Hajduk; M Hance; F H Hansen; J B Hansen; J D Hansen; P H Hansen; K Hara; A Harvey Jr; M Hauschild; C Hauviller; B M Hawes; R J Hawkings; H S Hayward; S J Haywood; F E W Heinemann; N P Hessey; J C Hill; M C Hodgkinson; P Hodgson; T I Hollins; A Holmes; R Holt; S Hou; D F Howell; W Hulsbergen; T Huse; Y Ikegami; Y Ilyushenka; C Issever; J N Jackson; V Jain; K Jakobs; R C Jared; G Jarlskog; P Jarron; L G Johansen; P Johansson; M Jones; T J Jones; D Joos; J Joseph; P Jovanovic; V A Kantserov; J Kaplon; M Karagoz Unel; F Kayumov; P T Keener; G D Kekelidze; N Kerschen; C Ketterer; S H Kim; D Kisielewska; B Kisielewski; T Kittelmann; E B Klinkby; P Kluit; S Kluth; B R Ko; P Kodys; T Koffas; E Koffeman; T Kohriki; T Kondo; N V Kondratieva; S P Konovalov; S Koperny; H Korsmo; S Kovalenko; T Z Kowalski; K Krüger; V Kramarenko; G Kramberger; M Kruse; P Kubik; L G Kudin; N Kundu; C Lacasta; V R Lacuesta; W Lau; A-C Le Bihan; S-C Lee; R P Lefevre; B C LeGeyt; K J C Leney; C G Lester; Z Liang; P Lichard; W Liebig; M Limper; A Lindahl; S W Lindsay; A Lipniacka; G Llosa Llacer; S Lloyd; A Loginov; C W Loh; M Lozano Fantoba; S Lucas; A Lucotte; I Ludwig; J Ludwig; F Luehring; L Luisa; J Lynn; M Maaßen; D Macina; R Mackeprang; A Macpherson; C A Magrath; P Majewski; P Malecki; V P Maleev; I Mandi?; M Mandl; M Mangin-Brinet; S Marti i Garcia; A J Martin; F F Martin; T Maruyama; R Mashinistov; A Mayne; K W McFarlane; S J McMahon; T J McMahon; J Meinhardt; B R Mellado Garcia; C Menot; I Messmer; B Mikulec; M Mikuž; S Mima; M Minano; B Mindur; V A Mitsou; P Modesto; S Moed; B Mohn; R M Moles Valls; J Morin; M-C Morone; S V Morozov; J Morris; H G Moser; A Moszczynski; S V Mouraviev; A Munar; W J Murray; K Nagai; Y Nagai; D Naito; K Nakamura; I Nakano; S Y Nesterov; F M Newcomer; R Nicholson; R B Nickerson; T Niinikoski; N Nikitin; R Nisius; H Ogren; S H Oh; M Olcese; J Olszowska; M Orphanides; V OShea; W Ostrowicz; B Ottewell; O Oye; E Paganis; M J Palmer; M A Parker; U Parzefall; M S Passmore; S Pataraia; G Pellegrini; H Pernegger; E Perrin; V D Peshekhonov; T C Petersen; R Petti; A W Phillips; P W Phillips; A Placci; K Poltorak; A Poppleton; M J Price; K Prokofiev; O Røhne; C Rembser; P Reznicek; R H Richter; A Robichaud-Veronneau; D Robinson; S Roe; O Rohne; A Romaniouk; L P Rossi; D Rousseau; G Ruggiero; K Runge; Y F Ryabov; A Salzburger; J Sanchez; H Sandaker; J Santander; V A Schegelsky; D Scheirich; J Schieck; M P Schmidt; C Schmitt; E Sedykh; D M Seliverstov; A Sfyrla; T Shin; A Shmeleva; S Sivoklokov; S Yu Smirnov; L Smirnova; O Smirnova; M Söderberg; A O Solberg; V V Sosnovtsev; L Sospedra Suay; H Spieler; G Sprachmann; E Stanecka; S Stapnes; J Stastny; M Stodulski; A Stradling; B Stugu; S Subramania; S I Suchkov; V V Sulin; R R Szczygiel; R Takashima; R Tanaka; G Tartarelli; P K Teng; S Terada; V O Tikhomirov; P Tipton; M Titov; K Toms; A Tonoyan; D R Tovey; A Tricoli; M Turala; M Tyndel; F Ukegawa; M Ullan Comes; Y Unno; V Vacek; S Valkar; J A Valls Ferrer; E van der Kraaij; R VanBerg; V I Vassilakopoulos; L Vassilieva; T Vickey; G H A Viehhauser; E G Villani; J H Vossebeld; T Vu Anh; R Wall; R S Wallny

2008-01-01

154

Glow discharge detector for terahertz and millimeter wave radiation detection and imaging  

Microsoft Academic Search

Glow discharge plasma, deriving from direct current gas breakdown, was investigated in order to realize an inexpensive THz room temperature detector. Preliminary results for THz radiation show that glow discharge indicator lamps as room temperature detectors yield good responsivity and NEP. Development of a Focal Plane Array (FPA) using such devices as detectors is advantageous since the costs of glow

A. Abromovich; N. S. Kopeika; D. Rozban

2007-01-01

155

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

Microsoft Academic Search

We consider a far infrared (terahertz), room-temperature detector based on a microcantilever sensor of the radiation pressure. This system has a significantly higher sensitivity than existing uncooled detectors in the far infrared (terahertz) spectral region. The significant enhancement of sensitivity is due the combination non-absorption detection method and high quality optical microcavity. Our theoretical analysis of the detector sensitivity and

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

2007-01-01

156

Study of multi-electrodes structure in CdTe nuclear radiation detectors  

Microsoft Academic Search

We studied CdTe nuclear radiation detectors with multi-electrodes structure. The detector consists of a common cathode, while the anode has been separated into three electrodes: the central collecting anode, a guard ring electrode, and a guiding electrode. The detector was biased in such a way that the central anode collects electrons while the guiding electrode repel electrons and guide them

Madan Niraula; Yasunori Agata; Kazuhito Yasuda

2004-01-01

157

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

158

Development of CdTe nuclear radiation detectors for spectroscopy and imaging applications  

Microsoft Academic Search

CdTe nuclear radiation detectors were developed for spectroscopy and imaging applications. Detectors were fabricated in two different techniques in order to alleviate the poor hole charge transport property in CdTe semiconductor. The first type comprises an M-?-n diode type detector fabricated by growing an n-type CdTe epitaxial layer on the p-like high resistivity CdTe crystal wafer. This detector is operated

M. Niraula; K. Yasuda; Y. Agata; A. Nakamura; T. Aoki; Y. Hatanaka

2003-01-01

159

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

160

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

161

Radiation detector based on liquid crystal light valve for large-area imaging applications  

Microsoft Academic Search

Currently most large-area radiation detectors rely on the use of a phosphor screen and an optical sensor. In such conversion process, there will be signal loss due to inefficiencies in coupling between phosphor screen and later light-detection components. This paper presents a radiation detector based on X-ray induced light transmittance of liquid crystal (LC) as a function of radiation. Our

Sangsik Kang; Byungyoul Cha; Sungho Cho; Jungwook Shin; Kunhwan Lee; Sanghee Nam

2007-01-01

162

Radiation damage effects by 25 MeV protons and thermal annealing effects on thallium bromide nuclear radiation detectors  

Microsoft Academic Search

In this study, TlBr detectors were irradiated with 25 MeV protons accelerated by an AVF cyclotron. Isothermal annealing was performed to restore the performance of the detectors. In order to characterize the radiation damage and thermal annealing effects on the TlBr detectors, we measured current-voltage (I-V) characteristics, mobility-lifetime (??) products and spectrometric responses. The I-V and ?? measurements suggest that

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

1999-01-01

163

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

164

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

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

165

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

NASA Astrophysics Data System (ADS)

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

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

166

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

167

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

Microsoft Academic Search

We consider a far infrared (terahertz), room-temperature detector based on a\\u000amicrocantilever sensor of the radiation pressure. This system has a\\u000asignificantly higher sensitivity than existing uncooled detectors in the far\\u000ainfrared (terahertz) spectral region. The significant enhancement of\\u000asensitivity is due the combination non-absorption detection method and high\\u000aquality optical microcavity. Our theoretical analysis of the detector\\u000asensitivity and

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

2007-01-01

168

Evaluation of a GEM and CAT-based detector for radiation therapy beam monitoring  

Microsoft Academic Search

We are developing a radiation therapy beam monitor for the Karolinska Institute. This monitor will consist of two consecutive detectors confined in one gas chamber: a “keV-photon detector”, which will allow diagnostic quality visualization of the patient, and a “MeV-photon detector”, that will measure the absolute intensity of the therapy beam and its position with respect to the patient. Both

A. Brahme; M. Danielsson; C. Iacobaeus; J. Ostling; V. Peskov; M. Wallmark

2000-01-01

169

The design and application of lithium drift silicon diodes as nuclear radiation detectors  

Microsoft Academic Search

A range of lithium-drifted silicon radiation detectors is described. Areas up to 8 cm2 and thicknesses up to 0.6 cm have been achieved. At - 20°C, a resolution of 8 kev full width half maximum was obtained on 661 kev beta particles using a 1 cm2 detector 0.1 cm thick. The performance of the detectors is discussed in relation to

P. E. Gibbons; N. G. Blamires

1965-01-01

170

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

171

Design of a Silicon Transition Radiation Detector (sitrd) for Accelerators and Space Applications  

Microsoft Academic Search

We are developing an unconventional Transition Radiation Detector (SiTRD), based on silicon strip detectors (SSDs) operating in a magnetic field region. The SiTRD combines the particle identification performance of a TRD with the high precision tracking capability of SSDs and can be suitable for both accelerator and cosmic ray experiments, where particle identification and momentum reconstruction are required. The main

M. Brigida; G. A. Caliandro; C. Favuzzi; P. Fusco; F. Gargano; N. Giglietto; F. Giordano; F. Loparco; B. Marangelli; M. N. Mazziotta; N. Mirizzi; S. Rainò; P. Spinelli; G. Barbarino; D. Campana; G. Osteria; S. Russo; V. Palladino; G. Barbiellini; F. Longo; A. de Angelis; B. de Lotto

2006-01-01

172

Very low-power consumption analog pulse processing ASIC for semiconductor radiation detectors  

Microsoft Academic Search

We describe a very-low power consumption circuit for processing the pulses from a semiconductor radiation detector. The circuit was designed for use with a cadmium zinc telluride (CZT) detector for unattended monitoring of stored nuclear materials. The device is intended to be battery powered and operate at low duty-cycles over a long period of time. This system will provide adequate

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

1998-01-01

173

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

Microsoft Academic Search

We describe a very-low power consumption circuit for processing the pulses from a semiconductor radiation detector. The circuit was designed for use with a cadmium zinc telluride (CZT) detector for unattended monitoring of stored nuclear materials. The device is intended to be battery powered and operate at low duty-cycles over a long period of time. This system will provide adequate

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

1999-01-01

174

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

DOEpatents

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

Whited, Richard C. (Santa Barbara, CA)

1981-01-01

175

Analyzing the Efficiency of the Forward Radiation Shielding for the CMS Detector at the LHC  

Microsoft Academic Search

The forward radiation shielding of the CMS detector is developed for the LHC by the Institute for High-Energy Physics. The efficiency of this shielding is analyzed on the basis of the results of numerical simulation. The computed particle-flux densities are compared to those of the ideal model of the shielding. The secondary-radiation field near the detector is investigated with different

I. L. Azhgirei; V. V. Talanov

2002-01-01

176

Comparison of radiation detector materials for imaging applications in nuclear medicine  

Microsoft Academic Search

Forty-two materials representing four classes of radiation detectors, including 15 scintillators, 13 Cerenkov radiators, 5 semiconductors and 9 wire chambers, are compared as detectors of 140 and 500 keV photons. For each material we list the 140 and 500 keV photon attenuation coefficients and half value thickness, the signal timing and amplitude characteristics, density and approximate cost per cubic centimetre.

I. Lavoie

1973-01-01

177

Growth and properties of semi-insulating CdZnTe for radiation detector applications  

Microsoft Academic Search

The growth and properties of semi-insulating CdZnTe for nuclear radiation detector applications are reviewed. The current state of the high-pressure Bridgman growth and the potentials of the conventional vertical and horizontal Bridgman techniques to grow radiation detector material are discussed. The characteristic macroscopic and microscopic defects of high-pressure Bridgman grown CdZnTe ingots, such as cracks, pipes, inclusions, precipitates, grain boundaries

Csaba Szeles; Michael C. Driver

1998-01-01

178

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

E-print Network

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

Berman, G P; Chernobrod, B M; Gorshkov, V N; Berman, Gennady P.; Bishop, Alan R.; Chernobrod, Boris M.; Gorshkov, Vyacheslav N.

2007-01-01

179

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

E-print Network

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

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

2007-03-05

180

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

181

GaN Radiation Detectors for Particle Physics and  

E-print Network

and as an UV light detector while the properties of single crystal diamond as a soft x-ray beam position irradiated wide band gap semiconductors, SiC and diamond. The maximum CCE of the thin epitaxial GaN detector

Glasgow, University of

182

Radiation detectors based on microchannel plates for free-electron lasers  

NASA Astrophysics Data System (ADS)

Detectors based on microchannel plates are used to detect the radiation of free-electron lasers operating in short-wavelength ranges. We present descriptions of radiation detectors for the FLASH free-electron laser (DESY, Hamburg) that operates in vacuum ultraviolet and soft X-ray wavelength ranges (4-100 nm) and detectors for the European X-ray free electron laser that is being constructed in Hamburg and is designed to operate in the X-ray wavelength range from 0.05 to 4.3 nm.

Syresin, E.; Brovko, O.; Grebentsov, A.; Zamjatin, N.; Shabunov, A.; Yurkov, M.; Gruenert, J.; Freund, W.; Novikov, D.; Basta, R.; Fiala, T.; Hedbavny, P.

2014-11-01

183

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

184

Methods for radiation detection and characterization using a multiple detector probe  

DOEpatents

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

Akers, Douglas William; Roybal, Lyle Gene

2014-11-04

185

Uncooled infrared and terahertz detectors based on micromechanical mirror as a radiation pressure sensor  

Microsoft Academic Search

We consider midinfrared (5 - 25 mum) and terahertz (100 - 1000 mum), room-temperature detectors based on a microcantilever\\/micromirror sensor of the radiation pressure. The significant enhancement of sensitivity is due the combination of non-absorption detection and a high quality optical microcavity. Applications for spectrometry and imaging are analyzed. It is shown that the radiation pressure sensor potentially has sensitivity

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

2009-01-01

186

Low radioactivity material for use in mounting radiation detectors  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

187

Method for mapping charge pulses in semiconductor radiation detectors  

SciTech Connect

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

Prettyman, T.H.

1998-12-01

188

Recent developments in radiation measurements using nuclear track detectors  

Microsoft Academic Search

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

G. M. Hassib

1994-01-01

189

A program in detector development for the US synchrotron radiation community  

SciTech Connect

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

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

2001-07-14

190

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

191

Coupled Deterministic/Monte Carlo Simulation of Radiation Transport and Detector Response  

SciTech Connect

The analysis of radiation sensor systems used to detect and identify nuclear and radiological weapons materials requires detailed radiation transport calculations. Two basic steps are required to solve radiation detection scenario analysis (RDSA) problems. First, the radiation field produced by the source must be calculated. Second, the response that the radiation field produces in a detector must be determined. RDSA problems are characterized by complex geometries, the presence of shielding materials, and large amounts of scattering (or absorption/re-emission). In this paper, we will discuss the use of the Attila code [2] for RDSA.

Gesh, Christopher J.; Meriwether, George H.; Pagh, Richard T.; Smith, Leon E.

2005-09-01

192

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

193

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

194

Study of the charge collection efficiency of CdZnTe radiation detectors  

NASA Astrophysics Data System (ADS)

The charge collection efficiency of CdZnTe radiation detectors with two different configurations: a Schottky diode detector and a resistive detector are compared. The average charge collection efficiencies for three different directions of irradiation (negative electrode, positive electrode and perpendicular to the electric field) are calculated. The mobility-lifetime product of the CdZnTe substrates is evaluated from the dependence of the measured spectra upon detector bias voltage. The measurement of the average charge collection efficiency is based on monitoring the shift of the peak channel with bias voltage in an experimental setup which is well calibrated. Two types of radiation are used: gamma photons from several radioactive sources and alpha particles from an241Am source. The models for the evaluation of mobility-lifetime product from the measured data for the two types of detector configurations as well as for the two types of radiation sources, are compared and discussed. The CdZnTe (Zn = 10%) substrates under study are obtained commercially and are grown by the high pressure Bridgeman method. The mobility-lifetime products and specific resistivity of the two types of detectors are evaluated and compared. A lower resistivity material has a narrower depletion region and behaves like a thinner detector thus exhibiting better collection efficiencies. Therefore, medium resistivity material which is completely inadequate for resistive detectors can still yield high performance Schottky detectors. The preferred direction of irradiation, i.e. from the negative electrode, is possible only in the case of n-type material which is reverse biased by negative voltages applied to the Schottky gate. The mobility-lifetime products that are derived on both the resistive detector (with specific resistivity of ?1.1010 ?.cm) and the Schottky diode (with specific resistivity of ?1.106 ?.cm) are ?n?n ?-4.10-4 cm2V-1 and ?p?p? 8.10-5 cm2V-1.

Nemirovsky, Y.; Ruzin, A.; Asa, G.; Gorelik, J.

1996-08-01

195

Study of edgeless radiation detector with 3D spatial mapping technique  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

196

Active noise canceling system for mechanically cooled germanium radiation detectors  

DOEpatents

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

Nelson, Karl Einar; Burks, Morgan T

2014-04-22

197

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

198

Preparation and Characteristics of Natural Diamond Nuclear Radiation Detectors  

Microsoft Academic Search

It is shown that natural diamond can be used as a homogeneous conduction counter with near complete charge collection, even over a long period of time. Indeed, polarization effects have been suppressed by making the back contact of the detector injecting under the influence of the applied field in order to compensate for trapped charge carriers. The electric and detection

S. F. Kozlov; R. Stuck; M. Hage-Ali; P. Siffert

1975-01-01

199

Properties of melt-grown ZnSe solid-state radiation detectors  

Microsoft Academic Search

Zinc Selenide (ZnSe) crystals grown using the High Pressure Bridgman (HPB) technique were used to fabricate solid-state radiation detectors measuring 10×10×2 mm3 Sputtered platinum and gold contacts were applied to polished detector blanks. Voltage versus current characteristics were determined for the devices at 25°C. Pulse height spectra were obtained using 241Am and 109Cd at both 25°C and 150°C with applied

E. E. Eissler; K. G. Lynn

1995-01-01

200

Integrated readout electronics: enabling advanced applications of position-sensitive solid-state radiation detectors  

Microsoft Academic Search

As applications of advanced solid-state radiation detector arrays proliferate across disciplines ranging from X-ray astronomy and medical imaging to security and industrial inspection, the relative scarcity of low-noise, multi-channel integrated circuits (ICs) needed to read out these arrays has become increasingly apparent. In fact, readout ICs are now regarded to be an integral part of position-sensitive semiconductor detectors for X-ray

Victoria B. Cajipe; Robert F. Calderwood; Martin Clajus; Satoshi Hayakawa; Tümay O. Tümer; Shi Yin

2004-01-01

201

High-Energy Proton Radiation Damage of High-Purity Germanium Detectors  

Microsoft Academic Search

Motivated by their applicability to gamma-ray spectroscopy experiments in space, quantitative studies of radiation damage effects in high-purity germanium detectors due to high-energy charged particles have been initiated with the irradiation by 6 GeV\\/c protons of two 1.0 cm thick planar detectors maintained at 88°K. The threshold for resolution degradation and the annealing characteristics differ markedly from those previously observed

Richard H. Pehl; Larry S. Varnell; Albert E. Metzger

1978-01-01

202

Development of Various Catheter Semiconductor Radiation Detectors and Their Application to Clinical Medicine  

Microsoft Academic Search

A catheter semiconductor radiation detector (CASRAD) probe which can be placed safely inside a human body for the measurement of beta-ray activity was developed. To fulfill specific requirements arising from medical purposes, the detector element of the CASRAD probe is made by a silicon p-n junction diode of single-ended coaxial structure, 2.3 mm in diameter and 1-4 mm long. Difficulties

S. Takayanagi; T. Kobayashi; T. Sugita; M. Iio; Y. Sasaki

1972-01-01

203

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

Microsoft Academic Search

Thallium bromide (TlBr) is a compound semiconductor with a high atomic number and wide band gap, being a very promising material to be used as room temperature radiation detectors. In this work, the 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

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

2003-01-01

204

Design of Low-Noise Vacuum-Tube Pulse Amplifiers for Semiconductor Radiation-Detector Spectroscopy  

Microsoft Academic Search

The pulse-height resolution of semiconductor nuclear-radiation detectors for particle energies below 200 kev is primarily limited by detector and amplifier noise. Amplifier noise may be large compared to that contributed by cooled, deep-depletionlayer diodes, and minimum noise is achieved by optimizing amplifier design for specific diode parameters. Vacuum-tube performance is realistically evaluated by measuring equivalent noise resistances of both plate-current

J. L. Blankenship

1964-01-01

205

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

206

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

207

Measuring Neutrons and Gamma Rays on Mars — The Mars Science Laboratory Radiation Assessment Detector MSL/RAD  

NASA Astrophysics Data System (ADS)

The Mars Science Laboratory (MSL) Radiation Assessment Detector (RAD) will measure the radiation environment including the neutral component on the martian surface. We present initial studies on the inversion of neutron calibration results.

Wimmer-Schweingruber, R. F.; Martin, C.; Kortmann, O.; Boehm, E.; Boettcher, S.; Kharytonov, A.; Ehresmann, B.; Hassler, D. M.; Zeitlin, C.

2010-03-01

208

Development of passive radiation detectors of improved sensitivity  

NASA Astrophysics Data System (ADS)

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

Chakrabarty, M. R.

1986-11-01

209

Development of passive radiation detectors of improved sensitivity  

NASA Technical Reports Server (NTRS)

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

Chakrabarty, M. R.

1986-01-01

210

Growth and properties of semi-insulating CdZnTe for radiation detector applications  

NASA Astrophysics Data System (ADS)

The growth and properties of semi-insulating CdZnTe for nuclear radiation detector applications are reviewed. The current state of the high-pressure Bridgman growth and the potentials of the conventional vertical and horizontal Bridgman techniques to grow radiation detector material are discussed. The characteristic macroscopic and microscopic defects of high-pressure Bridgman grown CdZnTe ingots, such as cracks, pipes, inclusions, precipitates, grain boundaries and their effect on the electrical and charge trapping properties of the material are reviewed.

Szeles, Csaba; Driver, Michael C.

1998-07-01

211

An advanced SiC nuclear radiation detector  

Microsoft Academic Search

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

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

1997-01-01

212

Radiation Detectors for HEP Applications Using Standard CMOS Technology  

Microsoft Academic Search

The suitability of standard CMOS technology featuring no epitaxial layer for particle detection has been investigated through extensive experimental characterization. Different pixel layout and read-out schemes have been devised and implemented, as well as different test strategies. In this work test results are reported concerning the response of the detector to IR laser, beta-particles and X-rays stimuli, thus confirming the

D. Passeri; A. Marras; P. Placidi; P. Delfanti; D. Biagetti; L. Servoli; G. M. Bilei; P. Ciampolini

2006-01-01

213

[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

214

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

SciTech Connect

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

Ciancaglioni, I.; Marinelli, Marco; Milani, E.; Prestopino, G.; Verona, C.; Verona-Rinati, G.; Consorti, R.; Petrucci, A.; De Notaristefani, F. [INFN-Dipartimento di Ingegneria Industriale, Universita di Roma 'Tor Vergata',Via del Politecnico 1, I-00133 Roma (Italy); U.O. Fisica Sanitaria, Ospedale San Filippo Neri, Via G. Martinotti 20, 00135 Roma (Italy); INFN-Dipartimento di Fisica, Universita Roma 3, Via della Vasca Navale 84, 00146 Roma (Italy)

2012-07-15

215

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

216

Characteristic of a PDP-based radiation detector in Xe-He mixture gas  

NASA Astrophysics Data System (ADS)

In this study, we have investigated a 2-dimensional gas detector based on plasma display technology as a candidate for the flat-panel radiation detector. Using the Geant4 and Garfield codes, that simulate the passage of particles through matter, we examined the dependence of X-ray absorption and multiplication factors on the Xe-He gas mixture. Prototype detectors, with four different gas mixtures, were designed and fabricated based on the results from the simulations. The performance of four detectors was evaluated by measuring the collected charge density, dark current density and sensitivity. The maximum collected charge occurred when the Xe 80%-He 20% gas mixture was 1.216 ?C/cm2 at -1800 V. The dark current of this detector varied between 0.124 and 0.321 nA/cm2 in the bias range of -300 to -1800 V, which is approximately one-third of the dark current density of an a-Se based detector, in this range. The sensitivity of Xe 80%-He 20% detector was 0.246 nC/mRcm2 at 0.61 V/?m. It is about a tenth lower than that of an a-Se based detector at 10 V/?m.

Eom, S.; Kang, J.; Lee, H.; Lee, K.

2013-04-01

217

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

SciTech Connect

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

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

2011-10-15

218

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

DOEpatents

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

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

1989-01-01

219

Novel Technique for Radiation Measurements: Fluorescent Nuclear Track Detectors  

Microsoft Academic Search

A new optical, non-destructive method of detecting and imaging single heavy charged particles using a fluorescent crystal is described. The new tool is intended for radiobiology, space radiation dosimetry and for personnel monitoring of neutron doses. The technique combines a new luminescent aluminum oxide single crystal with confocal fluorescent detection. 3D imaging of individual tracks allows for measuring ion range

M. S. Akselrod; R. C. Yoder; G. M. Akselrod; E. R. Benton; N. Yasuda

2005-01-01

220

Radiation detector and method of opaquing the mica window  

Microsoft Academic Search

An improved particle detection tube is disclosed including a method for applying a radiation transparent electrically non-conductive, opaque to ultraviolet light coating to the mica window of the tube. The coating reduces erroneous counts by preventing arcing between the tube anode and window. A purified mineral bituminous hydrocarbon based wax coating is applied to the mica window by cleaning the

H. Morris; C. Christianson

1983-01-01

221

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

222

Radiation detectors and sources enhanced with micro/nanotechnology  

NASA Astrophysics Data System (ADS)

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

Whitney, Chad Michael

223

Measurement of thermal radiation using regular glass optics and short-wave infrared detectors.  

PubMed

The measurement of thermal radiation from ambient-temperature objects using short-wave infrared detectors and regular glass optics is described. The detectors are chosen to operate in the 2.0 microm to 2.5 microm atmospheric window. Selection of detectors with high shunt resistance along with the 4-stage thermo-electric cooling of the detectors to -85 degrees C results in detectivity, D*, of 4 x 10(13) cm Hz(1/2)/W which is near the background limited performance at 295 K. Furthermore, the use of regular-glass commercial optics to collect the thermal radiation results in diffraction-limited imaging. The use of a radiation thermometer constructed with these elements for the measurement of a blackbody from 20 degrees C to 50 degrees C results in noise-equivalent temperature difference (NETD) of < 3 mK at 50 degrees C. The operation at shorter wavelengths than traditional thermal sensors also leads to lower sensitivity to the emissivity of the object in determining the temperature of the object. These elements are used to construct a calibrator for an infrared collimator, and such a system demonstrates noise-equivalent irradiances of < 5 fW/cm(2). These results indicate that radiometers using short-wave infrared sensors could be constructed utilizing commercial glass optics with possible better performance and lower NETD than existing radiometers using cryogenically-cooled mid-infrared or thermal infrared detectors. PMID:18542168

Yoon, H W; Eppeldauer, G P

2008-01-21

224

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

225

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

226

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

SciTech Connect

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

Sorokin, A.A. [Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin (Germany); Ioffe Physico-Technical Institute RAS, Polytekhnicheskay 26, 194021 St.Petersburg (Russian Federation); Bobashev, S.V.; Shmaenok, L.A. [Ioffe Physico-Technical Institute RAS, Polytekhnicheskay 26, 194021 St.Petersburg (Russian Federation); Feldhaus, J.; Gerth, Ch.; Hahn, U.; Steeg, B.; Tiedtke, K.; Treusch, R. [Deutsches Elektronen-Synchrotron, DESY, Notkestr. 85, 22603 Hamburg (Germany); Gottwald, A.; Kroth, U.; Richter, M. [Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin (Germany)

2004-05-12

227

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

228

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

229

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

ERIC Educational Resources Information Center

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

Consumer Dynamics Inc., Rockville, MD.

230

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

Microsoft Academic Search

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

L. Abbene; G. Gerardi

2011-01-01

231

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

E-print Network

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

Roma "La Sapienza", Università di

232

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

233

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

PubMed

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. PMID:19044527

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

2008-10-01

234

Radiation effects in polymers for plastic scintillation detectors  

SciTech Connect

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

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

1994-04-20

235

Digital configurable instrument for emulation of signals from radiation detectors  

SciTech Connect

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

Abba, A.; Caponio, F.; Geraci, A. [Politecnico di Milano, Department of Electronics, Information and Bioengineering-DEIB, Milan 20133 (Italy)] [Politecnico di Milano, Department of Electronics, Information and Bioengineering-DEIB, Milan 20133 (Italy)

2014-01-15

236

Development of a Fast Transition Radiation and Tracking Detector for Cbm at Fair  

NASA Astrophysics Data System (ADS)

A transition radiation and tracking detector is being developed for the CBM heavy-ion experiment at the future facility FAIR (GSI, Darmstadt). An approach of such a detector based on pad-readout multi-wire proportional chambers is being studied, in particular with respect to the gain stability of these devices under particle rates of up to 105 Hz/cm2. Results of a first test beam campaign and of first measurements with an X-ray tube show that, for thin prototype detectors, such rates produce a moderate decrease (typically 5%) in pulse-height due to space-charge build-up, and also a slight degradation (5%) of the spatial resolution. Future activities aimed at improving and better quantifying the performance of this detector will be discussed.

Garabatos, Chilo

2006-04-01

237

Radiation detectors fabricated on high-purity GaAs epitaxial materials  

NASA Astrophysics Data System (ADS)

Epitaxial GaAs material shows a great potential in X-ray spectroscopy and radiography applications due to its high absorption efficiency and low defect density. Fabrication of pixel radiation detectors from high-purtity epitaxial GaAs has been developed further. The process is based on mesa etching for pixellisation and sputtering for metallization. The leakage currents of processed pad detectors are below 10 nA/cm2 at a reverse bias of 100 V and decrease exponentially with the temperature. Measurement with transient current technique (TCT) shows that electrons have a trapping time of 8 ns. Good spectroscopic result were obtained from both a pad detector and a hybridized Medipix GaAs detector.

Wu, X.; Kostamo, P.; Gädda, A.; Nenonen, S.; Riekkinen, T.; Härkönen, J.; Salonen, J.; Andersson, H.; Zhilyaev, Y.; Fedorov, L.; Eränen, S.; Mattila, M.; Lipsanen, H.; Prunnila, M.; Kalliopuska, J.; Oja, A.

2014-12-01

238

Calibrating the Photon Detector for an Experiment Measuring Radiative Decay of the Neutron  

NASA Astrophysics Data System (ADS)

Data acquisition has been completed on an experiment to measure the radiative decay mode of the neutron by registering the correlated proton, electron, and photon decay products. This experiment anticipates measuring the branching ratio and the photon energy spectrum to an uncertainty of 1%. To achieve this precision, the photon detector solid angle coverage was increased by a factor of 12. The detector consists of 12 bismuth germanate scintillating crystals coupled to avalanche photodiodes, and it operates in the cryogenic, high magnetic field environment of a superconducting solenoid. In the initial experiment, the dominant systematic uncertainty was photon detector resolution and gain drift, and to reduce this uncertainty a detailed calibration program was implemented. The background gamma ray spectrum was periodically measured to monitor for possible gain shifts during the run. Radioisotope calibrations were also performed to quantify the detector gain, efficiency, spatial dependence, and resolution. We present the details of these calibrations and describe the simulations used to interpret these data.

Cooper, Robert

2011-04-01

239

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

240

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

SciTech Connect

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

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

2011-11-15

241

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

NASA Astrophysics Data System (ADS)

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 the most performant technology suited for this specific application are presented. Specially designed gettering steps were applied by backside ion implantation and annealing for enhancing the minority carriers lifetime in the substrate material and for reducing leakage currents at orders less than 10 nA. After a complete presentation of the specific characteristics of the as obtained detectors, they were exposed and completely characterized in x-ray ambient up to dose levels of 10(superscript 8) rad (E greater than 50 keV). Solutions for increasing the detector sensitivity and stability in radiation environments are proposed.

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

1997-07-01

242

A Study of an Acrylic Cerenkov Radiation Detector.  

NASA Astrophysics Data System (ADS)

A simple threshold Cerenkov counter consisting of a thin UVT acrylic bar at an angle to a beam of particles is presented. The Cerenkov light emitted by the beam is trapped in the bar by total internal reflection and is detected by a phototube at the end of the acrylic bar. The intensity of the light vs the angle between the beam and the bar depends on the cerenkov angle and therefore measures the velocity of the beam. The beam consists of 2.5 MeV electrons from a Ruthinium radioactive source which are focused using a permanent magnet beam line. The experimental setup makes a very good junior/senior laboratory experiment to investigate Cerenkov radiation.

Porter, Brian; Bodek, Arie; Debarbaro, Pawel; Budd, Howard

1996-05-01

243

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

244

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

245

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

246

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

E-print Network

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

Fiore, S

2015-01-01

247

Electrodrift purification of materials for room temperature radiation detectors  

DOEpatents

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

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

1997-06-24

248

Electrodrift purification of materials for room temperature radiation detectors  

DOEpatents

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

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

1997-06-24

249

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

SciTech Connect

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

Boubanga-Tombet, S., E-mail: stephanealbon@hotmail.com; Tanimoto, Y.; Satou, A.; Suemitsu, T.; Otsuji, T. [Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-Ku, Sendai 980-8577 (Japan); Wang, Y.; Minamide, H.; Ito, H. [RIKEN Sendai, 519-1399 Aramaki Aoba, Aoba-ku, Sendai 980-0845 (Japan); Fateev, D. V.; Popov, V. V. [Kotelnikov Institute of Radio Engineering and Electronics (Saratov Branch), 410019 Saratov (Russian Federation); Saratov State University, 410012 Saratov (Russian Federation)

2014-06-30

250

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

251

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

252

Radiation detectors based on laser sintered Bi 4Ge 3O 12 ceramics  

NASA Astrophysics Data System (ADS)

Laser sintered bismuth germanate (Bi 4Ge 3O 12) ceramics were investigated from the point of view of its potential use in radiation detector devices. The light output, density of trap centers and radiation damage were comparatively discussed for laser sintered ceramic, conventional ceramic and single crystal. The scintillator efficiency of the laser sintered ceramics was 13% higher than that observed for furnace sintered ceramics and the radiation damage levels were the same for both samples up to a dose of 3200 Gy of ? radiation. The thermoluminescence results of the samples irradiated with UV and ?-rays provided strong indicatives that the inter-grain defects have the same nature of the bulk defects and do not contribute with new traps in the temperature range studied. Furthermore, the density of trapping centers in the laser sintered material was 50% lower than in the conventionally sintered ceramics.

Macedo, Zélia Soares; da Silva, Ronaldo Santos; Valerio, Mário Ernesto Giroldo; Hernandes, Antonio Carlos

2004-06-01

253

Modeling the response of thermoluminescence detectors exposed to low- and high-LET radiation fields.  

PubMed

Lithium fluoride thermoluminescence (TL) detectors, with different Li composition (Li-6 and Li-7) and various activators (LiF:Mg,Ti, LiF:Mg,Cu,P), are widely used for dosimetry in space. The primary radiation field in space is composed of fast electrons, protons and heavy charged particles (HCP). By its interaction with the structures of the spacecraft, this field may be modified inside the crew cabin. Therefore, calibration of TL detectors against a dose of gamma-rays is not sufficient for relating the TL readout to absorbed dose or to quantities relevant in radiation protection, without suitable correction. We introduce and calculate the detection efficiency, eta, relative to gamma-ray dose, of lithium fluoride detectors after proton and heavy charged particle (HCP) irradiation. We calculate eta for MCP-N (LiF:Mg,Cu,P) and for MTS-N (LiF:Mg,Ti) using microdosimetric models. The microdosimetric distributions used in these models (for HCP of charges between Z=1 to Z=8 and in the energy range between 0.3 MeV/amu and 20 MeV/amu) are calculated using an analytical model, based on the results of Monte Carlo simulated charged particle tracks using the MOCA-14 code. The ratio etaMCP-N/etaMTS-N for protons of stopping power (in water) below 10 keV/microm lies in the range between 0.65 and 1.0 and for HCP with Z>1--between 0.3 and 0.6. The stopping power of the particle is found not to be a unique parameter to scale the response of TL detectors. The combination of response of LiF:Mg,Cu,P and LiF:Mg,Cu,P detectors can be more suitable for a dose correction in space radiation fields. PMID:12793731

Olko, Pawel; Bilski, Pawel; Budzanowski, Maciej; Waligórski, Michael Patrick Russell; Reitz, Guenther

2002-12-01

254

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

NASA Technical Reports Server (NTRS)

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

Taherzadeh, M.

1976-01-01

255

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

256

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

SciTech Connect

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

Myers, D. R.

2010-01-01

257

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

258

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

259

A microfabricated steel and glass radiation detector with inherent wireless signaling  

NASA Astrophysics Data System (ADS)

This paper describes an investigation of the performance compromises imposed by a manufacturing approach that utilizes lithographic micromachining processes to fabricate a wireless beta/gamma radiation detector. The device uses in-package assembly of stainless steel electrodes and glass spacers. These elements are micromachined using photochemical etching and powder blasting, respectively. The detector utilizes a commercial, TO-5 package that is hermetically sealed at 760 Torr with an Ar fill-gas. Gas microdischarges between the electrodes, which are initiated by the radiation, transmit wideband wireless signals. The detector diameter and height are 9 and 9.6 mm, respectively, and it weighs 0.97 g. The device performance has been characterized using various sealed, radioisotope sources, e.g., 30-99 µCi from 137Cs (which is a beta and gamma emitter) and 0.1 µCi from 90Sr (which is a pure beta emitter). It has a measured output of >15.5 counts s-1 when in close proximity to 99 µCi from 137Cs. The wireless signaling spans 1.25 GHz at receiving antenna-to-detector distances >89 cm, when in close proximity to a 0.1 µCi 90Sr source. The estimated intrinsic detection efficiency (i.e. with the background rate subtracted) is 3.34% as measured with the biasing arrangement described in the paper.

Eun, Christine K.; Gianchandani, Yogesh B.

2011-01-01

260

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

261

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

SciTech Connect

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

Lelis Goncalez, Odair; Federico, Claudio Antonio; Mendes Prado, Adriane Cristina; Galhardo Vaz, Rafael; Tizziani Pazzianotto, Mauricio [Instituto de Estudos Avancados - IEAv/DCTA - Sao Jose dos Campos, SP (Brazil); Semmler, Renato [Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP - Sao Paulo, SP (Brazil)

2013-05-06

262

Optimizing the design of a silicon photomultiplier-based radiation detector  

Microsoft Academic Search

The silicon photomultiplier (SiPM) is a novel photo-sensor technology. This paper presents the design optimization process for implementing this technology in a scintillator-based radiation detector. The device provides the advantages of low current consumption, small dimensions, and high gain. These properties make SiPM of great interest for applications involving portable instrumentation. However, a novel approach to establish a set of

D. Ginzburg; N. Kopeika; J. Paran; I. Cohen-Zada; M. Ghelman; V. Pushkarsky; E. Marcus; A. Manor; T. Mazor; Y. Kadmon; Y. Cohen; A. Osovizky

2011-01-01

263

The Ways of Performance Imrovement of Radiation-Type Germanium Detectors  

Microsoft Academic Search

The results on the resolution of radiation detectors are analyzed. It is pointed out that resolution is limited by the ho le trapping on deep centers, that compensate initial conductivity. This trapping can be lowered by the elect ric fields exceeding the values 1.2 - 1.4 kV\\/cm, though the decrease of the background of impurities, that are present in Ge

N. B. Strokan; V. K. Yeryomin; V. P. Subashieva; N. I. Tisnek

1972-01-01

264

An investigation of single-crystal PbTe for nuclear radiation detector applications  

Microsoft Academic Search

Lead chalcogenide materials, with high atomic numbers for favorable detection efficiency and narrow band-gaps for fine energy resolution, hold promise as a medium for the detection of ionizing radiation. Their viability as a material basis for detectors is assessed by characterizing p-type lead telluride (PbTe) in single crystal form. Following mechanical polishing and chemical etching of the material, metallic electrodes

Geehyun Kim; Mark D. Hammig

2011-01-01

265

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

266

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

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

267

Nuclear Instruments and Methods in Physics Research A 419 (1998) 556--569 Radiation damage of silicon strip detectors in the NA50 experiment  

E-print Network

to 20 Mrad, with a very non-uniform radiation spatial distribution. Radiation effects in the detectors of the detector implies constant occupancy and therefore highly non-uni- form radiation levels. Estimated fluences Mrads of ionising radiation, respectively. As a result even the outermost strips, which obtained about

Ramello, Luciano

268

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

SciTech Connect

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

William H. Miller; Tushar Ghosh

2004-03-10

269

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

270

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

271

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

PubMed

Barium fluoride (BaF2) 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. BaF2 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 BaF2 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 BaF2 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. PMID:23902059

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

2013-07-01

272

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

NASA Astrophysics Data System (ADS)

Barium fluoride (BaF2) 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. BaF2 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 BaF2 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 BaF2 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; Zhang, Zichuan; Weng, Xiufeng; Liu, Junhong; Guan, Xingyin; Zhang, Kan; Li, Gang

2013-07-01

273

Radiation field of cosmic rays measured in low Earth orbit by CR-39 detectors  

NASA Astrophysics Data System (ADS)

In low Earth orbit astronauts are exposed to a radiation field composed of galactic cosmic rays, solar particles, particles in the Earth’s radiation belts and albedo neutrons and protons from the Earth’s atmosphere. Linear Energy Transfer (LET) spectra have been measured for the STS-108, STS-112 and ISS-7S missions. Measurement of the radiation fields is based on accurate measurements of recoils and fragments produced in CR-39 detectors by cosmic ray primary and secondary protons and heavier nuclei and by secondary neutrons. The measured LET spectra were used to determine the corresponding absorbed dose and dose equivalent. Total flux of Z ? 2 was estimated and a charge spectrum was measured for STS-108 and STS-112 missions. Comparisons are made with the predictions of cosmic ray transport models.

Zhou, D.; O'Sullivan, D.; Semones, E.; Heinrich, W.

274

Radiation Field of Cosmic Rays Measured in Low Earth Orbit by CR-39 Detectors  

NASA Astrophysics Data System (ADS)

In low earth orbit (LEO) astronauts are exposed to a radiation field composed of galactic cosmic rays, solar particles, particles in the Earth's radiation belts and albedo neutrons and protons from the Earth's atmosphere. LET spectra have been measured for the STS-108, STS-112 and ISS-7S missions. Measurement of the radiation fields is based on accurate measurements of recoils produced in CR-39 detectors by cosmic ray primary and secondary protons and heavier nuclei and by secondary neutrons. The measured LET spectra were used to determine the corresponding absorbed dose and dose equivalent. Total flux of Z?2 was estimated and a charge spectrum was measured for STS-108 and STS-112 missions. Comparisons are made with the predictions of cosmic ray transport models.

Zhou, D.; O'Sullivan, D.; Semones, E.; Heinrich, W.

275

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

276

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

277

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

278

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

279

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

280

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

281

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

282

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

SciTech Connect

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

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

2009-12-16

283

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

284

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

285

Bismuth germanate scintillators as detectors for high-energy gamma radiation  

NASA Astrophysics Data System (ADS)

The properties of bismuth germanate (BGO) relevant to the detection of high-energy gamma-rays are discussed on the basis of a comparison between a 76 mm diameter by 76 mm long BGO scintillator and a 152 mm diameter by 254 mm long NaI(Tl) crystal. The two detectors were exposed to monoenergetic gamma rays from the 12C(p, p'?) 12C reaction at the proton energy 17 MeV ( E? = 4.44, 12.71 and 15.11 MeV) and from the 1H(t, ?) 4He reaction at the triton energy 9 MeV( E? = MeV). The bismuth germanate detector has several properties which are important for the detection of high-energy gamma radiation.

Drake, Darrell M.; Nilsson, Leif R.; Faucett, John

286

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

287

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

288

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

289

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

290

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

291

Improved Growth Methods for LaBr3 Scintillation Radiation Detectors  

SciTech Connect

The objective is to develop advanced materials for deployment as high-resolution gamma ray detectors. Both LaBr3 and CeBr3 are advanced scintillation materials, and will be studied in this research. Prototype devices, in collaboration Sandia National Laboratories, will be demonstrated along with recommendations for mass production and deployment. It is anticipated that improved methods of crystal growth will yield larger single crystals of LaBr3 for deployable room-temperature operated gamma radiation spectrometers. The growth methods will be characterized. The LaBr3 and CeBr3 scintillation crystals will be characterized for light yield, spectral resolution, and for hardness.

Douglas S. McGregor

2011-05-01

292

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

293

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

294

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

295

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

SciTech Connect

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

Milincic, R.

2005-04-15

296

Hydrogenated amorphous silicon radiation detectors: Material parameters; radiation hardness; charge collection  

SciTech Connect

Properties of hydrogenated amorphous silicon p-i-n diodes relevant to radiation detection applications were studied. The interest in using this material for radiation detection applications in physics and medicine was motivated by its high radiation hardness and the fact that it can be deposited over large area at relatively low cost. Thick, fully depleted a-Si:H diodes are required for sufficient energy deposition by a charged particle and better signal to noise ratio. A sizeable electric field is essential for charge collection in a -Si:H diodes. The large density of ionized defects that exist in the i layer when the diode is under DC bias causes the electric field to be uniform. Material parameters, namely carrier mobility and lifetime and the ionized defect density in thick a-Si:H p-i-n diodes were studied by the transient photoconductivity method. The increase in diode leakage current with reverse bias over the operating bias was consistent with the Poole-Frenkel effect, involving excitation of carriers from neutral defects. The diode noise over the operating voltage range was completely explained in terms of the shot noise component for CR-(RC){sup 4} (pseudo-Gaussian) shaping at 3 {mu}s shaping time and the noise component at 0 V bias (delta and thermal noise) added in quadrature. Irradiation with 1 Mev neutrons produced no significant degradation in leakage current and noise at fluences exceeding 4 {times} 10{sup 14} cm{sup {minus}2}. Irradiation with 1.4 Mev proton fluence of 1 {times} 10{sup 14} cm{sup {minus}2} decreased carrier lifetime by a factor of {approximately}4. Degradation in leakage current and noise became significant at proton fluence of {approximately}10{sup 13} cm{sup {minus}2}.

Qureshi, S.

1991-01-01

297

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

SciTech Connect

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

Qureshi, S.

1991-01-01

298

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

299

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

300

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

301

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

NASA Astrophysics Data System (ADS)

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

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

2005-09-01

302

A fast time-to-digital converter for position-sensitive radiation detectors with delay line readouts  

Microsoft Academic Search

A fast time-to-digital converter (TDC) has been developed for use with position-sensitive radiation detectors having delay line readouts. The device is recommended for detector applications where high position resolution and low distortion are required at high rates. The device has 2 ns time resolution, less than 0.1% differential nonlinearity, and a recovery time of 70 ns. When used with a

Joseph A. Harder

1998-01-01

303

A fast time-to-digital converter for position-sensitive radiation detectors with delay line readouts  

Microsoft Academic Search

A fast time-to-digital converter (TDC) has been developed for use with position-sensitive radiation detectors having delay line readouts. The device is recommended for detector applications where high position resolution and low distortion are required at high rates. The device has 2 ns time resolution, less than 0.1% differential nonlinearity, and a recovery time of 70 ns. When used with a

Joseph A. Harder

1988-01-01

304

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

Microsoft Academic Search

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

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

2011-01-01

305

Development of nuclear radiation detectors with energy resolution capability based on CdTe-n+GaAs heterojunction diodes  

Microsoft Academic Search

CdTe-n+-GaAs heterojunction diodes for room-temperature nuclear radiation detectors have been developed and demonstrated. The heterojunction diode was fabricated by growing a thin n-type CdTe buffer layer followed by the undoped p-like CdTe layer of about a 100 ?m thickness on the n+-GaAs substrates using metal-organic vapor phase epitaxy. The diode detectors exhibited good rectification property and had the reverse leakage

Madan Niraula; K. Yasuda; K. Uchida; Y. Nakanishi; T. Mabuchi; Y. Agata; K. Suzuki

2005-01-01

306

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

Microsoft Academic Search

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

Frantisek Dubecký; Claudio Ferrari; Dusan Korytár; Enos Gombia; Vladimír Necas

2007-01-01

307

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

SciTech Connect

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

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

2012-02-08

308

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

NASA Astrophysics Data System (ADS)

Silicon detectors have gained in popularity since silicon became a widely used electronic semiconductor material. Silicon detectors are used in particle physics as well as imagers 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 based detectors including charged coupled devices (CCDs). Some of this research was performed in the framework of high luminosity particle physics experiments, along with radiation hardness studies of basic semiconductors devices. The building blocks of silicon pixel detectors including CCDs are simple PIN or PN structures partially or totally depleted, or even MOS and APD (Avalanche PhotoDiode) structures. Bulk or surface defects considerably affect the transport of free carriers. We propose here guidelines for pixel design. The method takes into account the properties of defects and will be tested through two pixel structures. The electrical properties of defects can be reduced to basic parameters, which can be introduced in a standard simulation code to make predictive simulations. We include an analytical model for defect build up derived from isochronal annealing experiments. Studying pixels detectors with different geometrical structures and fabricated with various semiconducting materials is made possible with this method. Its purpose is to provide an alternative to tedious and extensive radiation tests on fabricated detectors. Predicting the pixel behaviour w.r.t. defect properties is necessary for the long-term reliability of detectors and for making them radiation hard. A general method for pixel design is introduced and we will show how it can be used for the design of alternative (germanium) pixels.

Fourches, N. T.; Chipaux, R.

2015-01-01

309

Improvement of thick a-Si radiation detectors by field profile tailoring  

SciTech Connect

Application of thick ({approximately}50 {mu}m) a-Si p-i-n diodes as a direct radiation detector for minimum ionizing particles is hampered by the need to apply large bias voltages in order fully to deplete the detecting intrinsic layer, which typically contains 5 {minus} 10 {times} 10{sup 14} ionizable dangling bonds per CM{sup 3}. By insertion of thin p-type layers at intervals within the intrinsic layer, the required depletion voltage can be reduced by a factor of at least 1/(n+l) where n is the number of layers inserted. This principle is demonstrated for devices approximately 12{mu}m in thickness. It is shown that electron losses within the p type layer can be kept to minimum by choice of a low doping concentration for the introduced players.

Drewery, J.S.; Cho, G.; Jing, T.; Kaplan, S.N.; Mireshghi, A.; Perez-Mendez, V.; Wildermuth, D.

1992-04-01

310

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

E-print Network

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.

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

2007-11-06

311

Properties of melt-grown ZnSe solid-state radiation detectors  

SciTech Connect

Zinc Selenide (ZnSe) crystals grown using the High Pressure Bridgman (HPB) technique were used to fabricate solid-state radiation detectors measuring 10 x 10 x 2 mm{sup 3}. Sputtered platinum and gold contacts were applied to polished detector blanks. Voltage versus current characteristics were determined for the devices at 25 C. Pulse height spectra were obtained using {sup 241}Am and {sup 109}Cd at both 25 C and 150 C with applied bias of 9,000 V/cm. Current versus temperature was measured over the temperature range of 30 C to 150 C. Performance was measured at energies of 22.1 and 59.5 keV over a temperature range of {minus}70 C to 170 C. Current versus dose rate was measured with 662 keV gamma irradiation. A value of the Mobility-Lifetime product ({mu}{tau}) for electrons was estimated. Time and temperature dependence of photo-peak position using Pulse Height Analysis (PHA) was studied.

Eissler, E.E. [II-VI Inc., Saxonburg, PA (United States); Lynn, K.G. [Brookhaven National Lab., Upton, NY (United States). Dept. of Physics

1994-12-01

312

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

SciTech Connect

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

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

2011-05-15

313

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

314

Novel mm-wave and THz radiation active imaging system based on glow discharge detector (GDD) pixel  

Microsoft Academic Search

A novel imaging system for mm wavelength and THz radiation is presented in this paper. The imaging system is based upon an inexpensive neon indicator lamp or glow discharge detector (GDD) that serves as a pixel in a focal plane array (FPA). It was shown in previous investigations that inexpensive neon indicator lamp GDDs are quite sensitive to mm wavelength

N. S. Kopeika; A. Abramovich; D. Rozban

2008-01-01

315

Effects of the Resistivity and Crystal Orientation of the Silicon PIN Detector on the Dark Current and Radiation Response Characteristics  

Microsoft Academic Search

The effects of the resistivity and crystal orientation on the leakage current and radiation response characteristics have been studied. The detector with (111) oriented substrate shows higher leakage current than (100) orientation due to the higher interface trap density at the Si\\/SiO2 interface. And high resistive substrate shows larger leakage current than low resistive one because of its wider depletion

Kun-Sik Park; Jong-Moon Park; Yong-Sun Yoon; Jin-Gun Koo; Bo-Woo Kim; Chang-Joo Yoon; Kwang-Soo No

2006-01-01

316

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

317

The influence of preamorphization on the properties of shallow p+ n-junctions in silicon radiation detectors  

Microsoft Academic Search

Low resistivity p+-contacts of silicon radiation detectors can be prepared by boron implantation into a preamorphized surface layer, produced by a germanium implantation. Already at low annealing temperature T <= 600°C the solid phase epitaxy of the amorphous layer leads to high electrical boron activation and a low sheet resistivity Rs <= 300 Omega\\/□. It is shown that for the

J. von Borany; R. Kögler

1993-01-01

318

Instrumentation of a resonant gravitational radiation detector with a planar thin-film dc SQUID  

SciTech Connect

The instrumentation of a low-temperature three-mode gravitationa1 radiation antenna incorporating a low-noise dc SQUID provided by IBM is described. The feedback circuitry necessary to maintain the linearity and dynamic range of the SQUID was found to drive the resonant system due to high coupling between the input coil and the feedback coil of the SQUID. In order for this type of planar thin-film dc SQUID to be useful for gravitational radiation detectors and other applications requiring high Q input circuits, a solution to this feedback problem is needed. To this end, the nonlinear equations describing the dc SQUID with linear feedback are solved in terms of an isolated SQUID. The important feedback parameters for a high Q resonant system are found to be the slew rate of the electronics and the coupling constant ratio ..cap alpha../sup 2//sub i//sub f//..cap alpha../sup 2//sub f/, where ..cap alpha../sup 2//sub i//sub f/ is the energy coupling efficiency between the feedback coil and input coil and ..cap alpha../sup 2//sub f/ is the energy coupling efficiency between the feedback coil and the SQUID loop. Methods to reduce the effect of the feedback on the input circuit are also discussed.

Folkner, W.M.; Moody, M.V.; Richard, J.; Carroll, K.R.; Tesche, C.D.

1989-06-15

319

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

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

320

Response function measurement of layered type CVD single crystal diamond radiation detectors for 14 MeV neutrons  

SciTech Connect

Response function measurement of layered-type chemical vapor deposition single crystal diamond radiation detectors for 14 MeV neutrons was carried out. The detector had a layered structure that was composed of a boron-doped diamond layer of 0.5 {mu}m in thickness and a nondoped diamond layer of 20 {mu}m on an inexpensive high pressure and high temperature-type Ib diamond substrate. The detector had energy resolution of 2.6% for 5.5 MeV {alpha} particles. This experiment was mainly carried out in order to understand the present status of the detector as a 14 MeV neutron spectrometer and an extent of charge trapping. As result, a peak caused by the {sup 12}C(n,{alpha}{sub 0}){sup 9}Be reactions was clearly observed; the best energy resolution of 6% as for a synthetic diamond radiation detector was achieved. Detection efficiency was 3.2x10{sup -7} counts/unit neutron fluence. However, taking the energy resolution for {alpha} particles, etc., into account, the energy resolution for 14 MeV neutrons was not so high. Further improvement based on better crystal growth is indispensable.

Kaneko, J.H.; Teraji, T.; Hirai, Y.; Shiraishi, M.; Kawamura, S.; Yoshizaki, S.; Ito, T.; Ochiai, K.; Nishitani, T.; Sawamura, T. [Graduate School of Engineering, Hokkaido University, N13 W8, Kita-ku, Sapporo 060-8628 (Japan); Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Graduate School of Engineering, Hokkaido University, N13 W8, Kita-ku, Sapporo 060-8628 (Japan); Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Japan Atomic Energy Research Institute, Tokai-mura, Ibaraki 319-1195 (Japan); Graduate School of Engineering, Hokkaido University, N13 W8, Kita-ku, Sapporo 060-8628 (Japan)

2004-10-01

321

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

322

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

323

Ultra-thin laser-aided doped Li contacts on high-purity germanium nuclear radiation detectors  

NASA Astrophysics Data System (ADS)

A Q-switched ruby laser pulse ( ? = 0.6943 ?m, 25 ns fwhm) was used to melt vacuum-evaporated Li layers on high purity [ p = (1-6) × 10 10 cm -3] Ge for nuclear radiation detectors. The resulting higly doped contacts were extremely thin (?0.1 ?m), and stable at room temperature. Full width half maximum (fwhm) resolutions of 15.3 keV for 5.48 MeV 241Am ?-particles and 3.1 keV for 662 keV 137Cs ?-rays were obtained and show these contacts may be suitable for many detector applications.

Pearton, Stephen J.; Williams, Anthony A.

324

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

325

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

E-print Network

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

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

2005-01-01

326

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

327

LHCb: FPGA-based, radiation-tolerant on-detector electronics for the upgrade of the LHCb Outer Tracker Detector  

E-print Network

The LHCb experiment studies B-decays at the LHC. The Outer Tracker straw tubes detects charged decay particles. The on-detector electronics will be upgraded to be able to digitize and transmit drift-times at every LHC crossing without the need for a hardware trigger. FPGAs have been preferred to application-specific integrated circuits to implement dead-time free TDCs, able to transmit data volumes of up to 36 Gbits/s per readout unit, including the possibility of performing zero suppression. Extensive irradiation tests have been carried out to validate the usage of field-programmable devices in the hostile environment of the LHCb tracking system.

Vink, W

2013-01-01

328

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

PubMed Central

Schottky CdTe X-ray detectors exhibit excellent spectroscopic performance but suffer from instabilities. Hence it is of extreme relevance to investigate their electrical properties. A systematic study of the electric field distribution and the current flowing in such detectors under optical perturbations is presented here. The detector response is explored by varying experimental parameters, such as voltage, temperature, and radiation wavelength. The strongest perturbation is observed under 850 nm irradiation, bulk carrier recombination becoming effective there. Cathode and anode irradiations evidence the crucial role of the contacts, the cathode being Ohmic and the anode blocking. In particular, under irradiation of the cathode, charge injection occurs and peculiar kinks, typical of trap filling, are observed both in the current-voltage characteristic and during transients. The simultaneous access to the electric field and the current highlights the correlation between free and fixed charges, and unveils carrier transport/collection mechanisms otherwise hidden. PMID:23881140

Cola, Adriano; Farella, Isabella

2013-01-01

329

Electric field and current transport mechanisms in Schottky CdTe X-ray detectors under perturbing optical radiation.  

PubMed

Schottky CdTe X-ray detectors exhibit excellent spectroscopic performance but suffer from instabilities. Hence it is of extreme relevance to investigate their electrical properties. A systematic study of the electric field distribution and the current flowing in such detectors under optical perturbations is presented here. The detector response is explored by varying experimental parameters, such as voltage, temperature, and radiation wavelength. The strongest perturbation is observed under 850 nm irradiation, bulk carrier recombination becoming effective there. Cathode and anode irradiations evidence the crucial role of the contacts, the cathode being Ohmic and the anode blocking. In particular, under irradiation of the cathode, charge injection occurs and peculiar kinks, typical of trap filling, are observed both in the current-voltage characteristic and during transients. The simultaneous access to the electric field and the current highlights the correlation between free and fixed charges, and unveils carrier transport/collection mechanisms otherwise hidden. PMID:23881140

Cola, Adriano; Farella, Isabella

2013-01-01

330

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

331

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

SciTech Connect

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

Jack E. Malcom

1999-06-01

332

Measuring Neutrons and Gamma Rays on Mars - The Mars Science Laboratory Radiation Assessment Detector MSL/RAD  

NASA Astrophysics Data System (ADS)

The Mars Science Laboratory (MSL) missions Radiation Assessment Detector (RAD) will measure the radiation environment on the Martian surface. One of the difficult measurements is that of the neutral radiation component consisting of neutrons and gamma rays. Different from Earth, this neutral component contributes substantially to the total dose on the planetary surface, principally because the Martian atmosphere is so thin. We will present methods to invert neutral particle data acquired with MSL's RAD instrument and compare them with calibration data. While the agreement is good for neutrons from a calibration beam in a forward model, more work is required for omnidirectional neutrons with unknown spectral properties using other inversion techniques. We expect an asymmetry in fluxes from soil and sky for neutrons. Preliminary simulation results show a different behavior for gamma rays. Therefore, models of the IRF are likely to require additional inputs about the radiation environement.

Martin, Cesar; Kortmann, Onno; Boehm, Eckart; Boettcher, Stephan; Kharytonov, Alexander; Ehresmann, Bent; Wimmer-Schweingruber, Robert F.; Hassler, Donald M.; Zeitlin, Cary

2010-05-01

333

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

334

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

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

335

Effects of 1-MeV gamma radiation on a multi-anode microchannel array detector tube  

NASA Technical Reports Server (NTRS)

A multianode microchannel array (MAMA) detector tube without a photocathode was exposed to a total dose of 1,000,000 rads of 1-MeV gamma radiation from a Co-60 source. The high-voltage characteristic of the microchannel array plate, average dark count, gain, and resolution of pulse height distribution characteristics showed no degradation after this total dose. In fact, the degassing of the microchannels induced by the high radiation flux had the effect of cleaning up the array plate and improving its characteristics.

Timothy, J. G.; Bybee, R. L.

1979-01-01

336

A simulation study investigating a radiation detector utilizing the prompt gamma range verification technique for proton radiotherapy  

NASA Astrophysics Data System (ADS)

Proton therapy has shown to be a viable therapy for radiation oncology applications. The advantages of using protons as compared to photons in the treatments of diseases with radiation are numerous including the ability to deliver overall lower amounts of lethal radiation doses to the patient. This advantage is due to the fundamental interaction mechanism of the incident therapeutic protons with the patient, which produces a characteristic dose-distribution unique only to protons. Unlike photons, the entire proton beam is absorbed within the patent and the dose-distribution's maximum occurs near the end of the proton's path. Protons deliver less dose on the skin and intervening tissues, tighter dose conformality to the disease site, as well as no dose past the target volume, sparring healthy tissue distally in the patient. Current research in proton therapy is geared towards minimizing proton range uncertainty and monitoring in-vivo the location of the proton's path. Monitoring the beam's path serves also to verify which healthy structures/tissues were irradiated and whether the target volume has met the prescription dose. Among the many techniques used for in-vivo proton monitoring, the technique based on the emitted secondary particles, specifically the Prompt Gamma (PG) method, can be used for clinical implementation. This work focuses on developing a radiation detector system for using the PG method by investigating the characterizing the secondary particle field emitted from plastic and water phantoms as well as a radiation detector based on glass materials that exploits the Cherenkov phenomenon.

Lau, Andrew David

337

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

338

Modelling the effects of Te precipitates on the electron transport in CdZnTe radiation detectors  

Microsoft Academic Search

Large Te inclusions, >100?m, or aggregations of Te precipitates are known to degrade the performance of CdZnTe (CZT) nuclear-radiation detectors. At the same time, it is widely accepted that randomly distributed small Te precipitates are not harmful. Previous attempts to study Te precipitates, conducted with wide X-ray or alpha-particle beams, were unable to reveal their critical role because the 300–400

A. E. Bolotnikov; G. S. Camarda; G. A. Carini; Y. Cui; L. Li; R. B. James

2007-01-01

339

Modelling the effects of Te precipitates on the electron transport in CdZnTe radiation detectors  

Microsoft Academic Search

Large Te inclusions, >100 mum, or aggregations of Te precipitates are known to degrade the performance of CdZnTe (CZT) nuclear-radiation detectors. At the same time, it is widely accepted that randomly distributed small Te precipitates are not harmful. Previous attempts to study Te precipitates, conducted with wide X-ray or alpha-particle beams, were unable to reveal their critical role because the

A. E. Bolotnikov; G. S. Camarda; G. A. Carini; Y. Cui; L. Li; R. B. James

2007-01-01

340

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

Microsoft Academic Search

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

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

2011-01-01

341

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

Microsoft Academic Search

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

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

2007-01-01

342

In-situ minority carrier recombination lifetime measurements at radiation sources for rad-hard IR detector materials  

NASA Astrophysics Data System (ADS)

Minority carrier recombination lifetime (MCRL) is a key material parameter for space-based infrared (IR) detector performance affecting both dark current and responsivity. Displacement damage due to energetic massive particles in space environments, such as protons, can significantly degrade the recombination lifetime, thereby reducing detector performance. Therefore, characterizing the change in MCRL with proton dose is of general interest from a radiation-hardness perspective. So-called "bag tests," or measurements taken prior to and following room temperature proton irradiation of the device, are often of limited value to MCRL characterization since thermal annealing effects may be present. Here, progress toward a portable MCRL measurement system employing time resolved photoluminescence (TRPL) is presented. This system can be taken to remote radiation sources where irradiation can be performed on samples followed by TRPL measurements while maintaining temperature throughout. Ideally, this system permits measurement of a lifetime radiation damage factor constant, or the change in lifetime with step-wise changes in proton dose, which is a measure of the defect introduction rate. The pulsed-laser driven TRPL measurement system is able to interrogate IR materials of interest mounted in an optical cryostat held indefinitely at a desired temperature. A system description is given and results of verification measurements are discussed for several IR detector materials.

Jenkins, Geoffrey D.; Morath, Christian P.; Cowan, Vincent M.

2014-09-01

343

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

344

Frontal IBICC study of the induced proton radiation damage in CdTe detectors  

Microsoft Academic Search

Within a continuous international effort in developing the non-cryogenic semiconductor detectors for gamma ray spectroscopy, various wide gap materials were considered. With a best performance achieved, CdTe- and CdZnTe-based detectors become today widely accepted and commercially available. In addition to possible future use of such detectors for particle-induced gamma-ray emission (PIGE), nuclear microprobes are in recent years applied more as

Željko Pastuovi?; Milko Jakši?

2001-01-01

345

Influence of crystalline surface quality on TlBr radiation detector performance  

Microsoft Academic Search

In this study, TlBr detectors were fabricated from crystals purified by the multipass zone refining and grown by the Bridgman method. Detectors were prepared using TlBr 0.3-mm-thick wafers, with surface submitted to different mechanical and chemical treatments. Optical microscopy and scanning electron microscopy evaluated the TlBr wafers surface quality. To analyze the surface quality influence in the detector response, systematic

Icimone B. Oliveira; Fabio E. Costa; Pedro K. Kiyohara; Margarida M. Hamada

2005-01-01

346

Influence of crystalline surfaces on the TlBr radiation detector performance  

Microsoft Academic Search

Thallium bromide (TlBr) is an important material for room temperature detectors. Due to its high photoelectric absorption efficiency and large band gap, thallium bromide is a good candidate for X- and gamma-ray spectrometry. In this study, TlBr detectors were fabricated from the crystals purified by the multipass zone refining and grown by the Bridgman method. Detectors were prepared using TlBr

Icimone B. Oliveira; Fabio E. Costa; M. M. Hamada; P. K. Kiyohara

2004-01-01

347

Pion-to-proton ratio for unaccompanied high-energy cosmic-ray hadrons at mountain altitude using transition-radiation detector  

Microsoft Academic Search

A transition-radiation (TR) detector, consisting of 24 modules of styrofoam radiators and multiwire proportional chambers, and an ionization calorimeter have been used to measure the pion-to-proton ratio among the unaccompanied cosmic-ray hadrons at a mountain altitude of 730 g cm-2. Using the characteristics of the TR detector obtained from calibrations with particle beams at accelerators, the pip ratio has been

R. W. Ellsworth; A. S. Ito; J. R. MacFall; F. Siohan; R. E. Streitmatter; S. C. Tonwar; P. R. Viswanath; G. B. Yodh

1983-01-01

348

Development of nuclear radiation detectors with energy discrimination capabilities based on thick CdTe layers grown by metalorganic vapor phase epitaxy  

Microsoft Academic Search

We report on the development of nuclear radiation detectors based on epitaxially grown thick single crystalline CdTe layers. The optimization of the CdTe growth on the GaAs substrates in a metalorganic vapor phase epitaxy resulted high-structural quality and thick CdTe layers of thickness up to 200 mum. Radiation detectors were fabricated by growing a 2-5 mum thick iodine-doped n-CdTe buffer

K. Yasuda; M. Niraula; H. Kusama; Y. Yamamoto; M. Tominaga; K. Takagi; Y. Agata; K. Suzuki

2004-01-01

349

Development of nuclear radiation detectors with energy discrimination capabilities based on thick CdTe Layers grown by metalorganic vapor phase epitaxy  

Microsoft Academic Search

We report on the development of nuclear radiation detectors based on epitaxially grown thick single crystalline CdTe layers. The optimization of the CdTe growth on the GaAs substrates in a metalorganic vapor phase epitaxy resulted high-structural quality and thick CdTe layers of thickness up to 200 ?m. Radiation detectors were fabricated in p-CdTe\\/n-CdTe\\/n+-GaAs structure, where a 2-5 ?m thick iodine-doped

K. Yasuda; M. Niraula; H. Kusama; Y. Yamamoto; M. Tominaga; K. Takagi; Y. Agata; K. Suzuki

2005-01-01

350

Clinical radiation therapy measurements with a new commercial synthetic single crystal diamond detector.  

PubMed

A commercial version of a synthetic single crystal diamond detector (SCDD) in a Schottky diode configuration was recently released as the new type 60019 microDiamond detector (PTW-Freiburg, Germany). In this study we investigate the dosimetric properties of this detector to independently confirm that findings from the developing group of the SCDDs still hold true for the commercial version of the SCDDs. We further explore if the use of the microDiamond detector can be expanded to high-energy photon beams of up to 15 MV and to large field measure- ments. Measurements were performed with an Elekta Synergy linear accelerator delivering 6, 10, and 15 MV X-rays, as well as 6, 9, 12, 15, and 20 MeV electron beams. The dependence of the microdiamond detector response on absorbed dose after connecting the detector was investigated. Furthermore, the dark current of the diamond detector was observed after irradiation. Results are compared to similar results from measurements with a diamond detector type 60003. Energy dependency was investigated, as well. Photon depth-dose curves were measured for field sizes 3 × 3, 10 × 10, and 30 × 30 cm2. PDDs were measured with the Semiflex type 31010 detector, microLion type 31018 detector, P Diode type 60016, SRS Diode type 60018, and the microDiamond type 60019 detector (all PTW-Freiburg). Photon profiles were measured at a depth of 10 cm. Electron depth-dose curves normalized to the dose maximum were measured with the 14 × 14 cm2 electron cone. PDDs were measured with a Markus chamber type 23343, an E Diode type 60017 and the microDiamond type 60019 detector (all PTW-Freiburg). Profiles were measured with the E Diode and microDiamond at half of D90, D90, D70, and D50 depths and for electron cone sizes of 6 × 6 cm2, 14 × 14 cm2, and 20 × 20 cm2. Within a tol- erance of 0.5% detector response of the investigated detector was stable without any preirradiation. After preirradition with approximately 250 cGy the detector response was stable within 0.1%. A dark current after irradiation was not observed. The microDiamond detector shows no energy dependence in high energy photon or electron dosimetry. Electron PDD measurements with the E Diode and micro- Diamond are in good agreement. However, compared to E Diode measurements, dose values in the bremsstrahlungs region are about 0.5% lower when measured with the microDiamond detector. Markus detector measurements agree with E Diode measurements in the bremsstrahlungs region. For depths larger than dmax, depth-dose curves of photon beams measured with the microDiamond detector are in close agreement to those measured with the microLion detector for small fields and with those measured with a Semiflex 0.125 cc ionization chamber for large fields. Differences are in the range of 0.25% and less. For profile measurements, microDiamond detector measurements agree well with microLion and P Diode measurements in the high-dose region of the profile and the penumbra region. For areas outside the open field, P Diode measurements are about 0.5%-1.0% higher than microDiamond and microLion measurements. Thus it becomes evident that the investigated diamond detector (type 60019) is suitable for a wide range of applications in high-energy photon and electron dosimetry and is interesting for relative, as well as absolute, dosimetry.  PMID:25493512

Laub, Wolfram U; Crilly, Richard

2014-01-01

351

Properties of thin film radiation detectors and their application to dosimetry and quality assurance in x-ray imaging  

NASA Astrophysics Data System (ADS)

The characteristics of two different types of thin-film radiation detectors are experimentally investigated: organic photovoltaic cells (OPV) and a new self-powered detector that operates based on high-energy secondary electrons (HEC). Although their working principles are substantially different, they both can be used for radiation detection and image formation in medical applications. OPVs with different active layer material thicknesses and aluminum electrode areas were fabricated. The OPV cell consisted of P3HT: PCBM photoactive materials, composed of donor and acceptor semiconducting organic materials, sandwiched between an aluminum electrode as anode and an indium tin oxide (ITO) electrode as a cathode. The detectors were exposed to 60150 kVp x rays, which generated photocurrent in the active layer. The electric charge production in the OPV cells was measured. The net current as function of beam energy (kVp) was proportional to ~1/kVp0.45 when adjusted for x-ray beam output. The best combination of parameters for these cells was 270-nm active layer thicknesses for 0.7cm-2 electrode area. The measured current ranged from about 0.7 to 2.4 nA/cm2 for 60-150 kVp, corresponding to about 0.09 -- 0.06 nA/cm2/mGy, respectively, when adjusted for the output x-ray source flux. The HEC detection concept was recently proposed and experimentally demonstrated by a UML/HMS research group. HEC detection employs direct conversion of high-energy electron current to detector signal without external power and amplification. The potential of using HEC detectors for diagnostic imaging application was investigated by using a heterogeneous phantom consisting of a water cylinder with Al and wax rod inserts.

Elshahat, Bassem

352

Monte Carlo simulation of beta radiation response function for semiconductor Si detector  

Microsoft Academic Search

This paper describes the modeling of the Passivated Implanted Planar Silicon (PIPS) detector for the beta particles response function simulations with the MCNP-5 code. The simulated and measured energy response functions were compared and a good agreement was found in the entire range of energies. The verified model of a PIPS detector was applied in a non-destructive method that determines

Selena Grujic; Miodrag Milosevic; Uranija Kozmidis-Luburic; Istvan Bikit

2011-01-01

353

POWER MONITORING IN SPACE NUCLEAR REACTORS USING SILICON CARBIDE RADIATION DETECTORS  

Microsoft Academic Search

Space reactor power monitors based on silicon carbide (Sic) semiconductor neutron detectors are proposed. Detection of fast leakage neutrons using Sic detectors in ex-core locations could be used to determine reactor powel: Neutron fluxes, gamma-ray dose rates and ambient temperatures have been calculated as a function of distance from the reactor core, and the feasibility of power monitoring with Sic

Frank H. Ruddy; Jagdish U. Pate; John G Williams

2005-01-01

354

Advances in silicon detectors for particle tracking in extreme radiation environments  

Microsoft Academic Search

The LHC (Large Hadron Collider) is currently under construction at CERN, the European Laboratory for Particle Physics based in Geneva. The experiments at this accelerator will use substantial numbers of silicon detectors. These are close to the interaction point and will be exposed to very high fluences ( up to 1015particlescm?2) during their operating life. Such detectors are crucial to

C. Da Via; G. Anelli; J. Hasi; P. Jarron; C. Kenney; A. Kok; Sherwood Parker; E. Perozziello; S. J. Watts

2003-01-01

355

Radiation detection and measurement  

Microsoft Academic Search

Introductory material covers radiation sources, radiation interactions, general properties of radiation detectors, and counting statistics and error prediction. This is followed by detailed sections on gas-filled detectors, scintillation counters, semiconductor detectors, neutron detectors and spectroscopy, detector electronics and pulse processing, and miscellaneous radiation detectors and applications.

Glenn F. Knoll

1979-01-01

356

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

357

Processing and characterization of edgeless radiation detectors for large area detection  

NASA Astrophysics Data System (ADS)

The edgeless or active edge silicon pixel detectors have been gaining a lot of interest due to improved silicon processing capabilities. At VTT, we have recently triggered a multi-project wafer process of edgeless silicon detectors. Totally 80 pieces of 150 mm wafers were processed to provide a given number of detector variations. Fabricated detector thicknesses were 100, 200, 300 and 500 ?m. The polarities of the fabricated detectors on the given thicknesses were n-in-n, p-in-n, n-in-p and p-in-p. On the n-in-n and n-in-p wafers the pixel isolation was made either with a common p-stop grid or with a shallow p-spray doping. The wafer materials were high resistivity Float Zone and Magnetic Czochralski silicon with crystal orientation of <100>. In this paper, the electric properties on various types of detectors are presented. The results from spectroscopic measurement show a good energy resolution of the edge pixels, indicating an excellent charge collection near the edge pixels of the edgeless detector.

Kalliopuska, J.; Wu, X.; Jakubek, J.; Eränen, S.; Virolainen, T.

2013-12-01

358

Photon noise limited radiation detection with lens-antenna coupled microwave kinetic inductance detectors  

SciTech Connect

Microwave kinetic inductance detectors (MKIDs) have shown great potential for sub-mm instrumentation because of the high scalability of the technology. Here, we demonstrate for the first time in the sub-mm band (0.1-2 mm) a photon noise limited performance of a small antenna coupled MKID detector array and we describe the relation between photon noise and MKID intrinsic generation-recombination noise. Additionally, we use the observed photon noise to measure the optical efficiency of detectors to be 0.8 {+-} 0.2.

Yates, S. J. C.; Baselmans, J. J. A.; Diener, P. [SRON, Sorbonnelaan 2, 3584 CA Utrecht (Netherlands); Endo, A.; Janssen, R. M. J. [Kavli Institute of NanoScience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (Netherlands); Ferrari, L. [SRON, Landleven 12, 9747 AD Groningen (Netherlands); Baryshev, A. M. [SRON, Landleven 12, 9747 AD Groningen (Netherlands); Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV Groningen (Netherlands)

2011-08-15

359

Effects of post-growth annealing on the performance of CdZnTe: In radiation detectors with different thickness  

NASA Astrophysics Data System (ADS)

An effective post-growth annealing method was used to improve the performance of CdZnTe:In (CZT:In) radiation detectors. The results indicated that Te inclusions in CZT:In crystals with different thickness were eliminated completely after annealing. Both the resistivity and IR transmittance of annealed CZT:In crystals with different thickness increased obviously, which suggested that the crystal quality was improved. For the detector fabricated by annealed CZT:In slices with 2 mm thickness, the energy resolution and (??)e value were enhanced about 63% and 115%, respectively. And for that fabricated by annealed CZT:In slices with 5 mm thickness, the energy resolution and (??)e value were enhanced about 300% and 88%, respectively.

Yu, Pengfei; Jie, Wanqi

2014-02-01

360

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

361

Progress in the development of two-dimensional multiwire detectors for X-ray synchrotron radiation experiments  

SciTech Connect

A report is presented of the developments in two-dimensional, multiwire detectors for X-ray synchrotron radiation experiments, using delay line position readout. Advances have been made in methods of cathode design and fabrication, a description is given of the trade-off between position resolution and count rate capability, and the importance of low dead-time TDCs is illustrated. A detector has been operating successfully for well over a year at the time resolved, scattering station of the National Synchrotron Light Source; results are presented from this which illustrate the very good resolution (100 {mu}m FWHM), differential non-linearity ({plus_minus}4%) and absolute position stability of these devices, and the importance of low differential non-linearity for these types of experiment.

Smith, G.C.; Yu, B.; Capel, M.

1993-06-01

362

Electromechanically cooled germanium radiation detector system 1 Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under Contract W-7405Eng48. 1  

Microsoft Academic Search

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

Anthony D Lavietes; G Joseph Mauger; Eric H Anderson

1999-01-01

363

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

364

Optimization of Radiation Dose in Cardiac and Vascular Multirow-Detector CT  

Microsoft Academic Search

The radiation dose is becoming a major issue for contrast-enhanced cardiac CT (coronary CT angiography), because the radiation\\u000a level associated with ECG-gated acquisition is generally higher than that with other CT acquisitions. However, multiphasic\\u000a acquisitions of other organs (for example liver) may also be associated with a comparable or even higher total radiation,\\u000a so this large radiation dose is not

Jean-François Paul; Hicham T. Abada

365

Experimental investigations of a loop antenna as electron plasma wave radiator and detector  

Microsoft Academic Search

The radiation and reception characteristics of a circular loop antenna for an electron plasma wave are investigated experimentally. As a result, it is shown that the measured directional radiation and reception patterns agree well with the theoretically predicted ones, and that the quantitatively measured amplitude of the radiated wave potentials are also found to agree fairly well with the theoretically

SHIGEO OHNUKI; SABURO ADACHI; TOSHIRO OHNUMA

1977-01-01

366

Power monitoring in space nuclear reactors using silicon carbide radiation detectors  

NASA Technical Reports Server (NTRS)

Space reactor power monitors based on silicon carbide (SiC) semiconductor neutron detectors are proposed. Detection of fast leakage neutrons using SiC detectors in ex-core locations could be used to determine reactor power: Neutron fluxes, gamma-ray dose rates and ambient temperatures have been calculated as a function of distance from the reactor core, and the feasibility of power monitoring with SiC detectors has been evaluated at several ex-core locations. Arrays of SiC diodes can be configured to provide the required count rates to monitor reactor power from startup to full power Due to their resistance to temperature and the effects of neutron and gamma-ray exposure, SiC detectors can be expected to provide power monitoring information for the fill mission of a space reactor.

Ruddy, Frank H.; Patel, Jagdish U.; Williams, John G.

2005-01-01

367

Charged particle spectra obtained with the Mars Science Laboratory Radiation Assessment Detector (MSL/RAD) on the surface of Mars  

NASA Astrophysics Data System (ADS)

The Radiation Assessment Detector (RAD)—situated inside the Mars Science Laboratory's Curiosity rover—is the first ever instrument to measure the energetic particle radiation environment on the surface of Mars. To fully understand the influence of this surface radiation field in terms of potential hazard to life, a detailed knowledge of its composition is necessary. Charged particles are a major component of this environment, both galactic cosmic rays propagating to the Martian surface and secondary particles created by interactions of these cosmic rays with the atoms of the Martian atmosphere and soil. Here we present particle fluxes for a wide range of ion species, providing detailed energy spectra in the low-energy range (up to several hundred MeV/nucleon particle energy), and integral fluxes for higher energies. In addition to being crucial for the understanding of the hazards of this radiation to possible future manned missions to Mars, the data reported here provide valuable input for evaluating and validating particle transport models currently used to estimate the radiation environment on Mars and elsewhere in space. It is now possible for the first time to compare model results for expected surface particle fluxes with actual ground-based measurements.

Ehresmann, Bent; Zeitlin, Cary; Hassler, Donald M.; Wimmer-Schweingruber, Robert F.; Böhm, Eckart; Böttcher, Stephan; Brinza, David E.; Burmeister, Sönke; Guo, Jingnan; Köhler, Jan; Martin, Cesar; Posner, Arik; Rafkin, Scot; Reitz, Günther

2014-03-01

368

Field calibration of PADC track etch detectors for local neutron dosimetry in man using different radiation qualities  

NASA Astrophysics Data System (ADS)

In order to quantify the dose from neutrons to a patient for contemporary radiation treatment techniques, measurements inside phantoms, representing the patient, are necessary. Published reports on neutron dose measurements cover measurements performed free in air or on the surface of phantoms and the doses are expressed in terms of personal dose equivalent or ambient dose equivalent. This study focuses on measurements of local neutron doses inside a radiotherapy phantom and presents a field calibration procedure for PADC track etch detectors. An initial absolute calibration factor in terms of Hp(10) for personal dosimetry is converted into neutron dose equivalent and additional calibration factors are derived to account for the spectral changes in the neutron fluence for different radiation therapy beam qualities and depths in the phantom. The neutron spectra used for the calculation of the calibration factors are determined in different depths by Monte Carlo simulations for the investigated radiation qualities. These spectra are used together with the energy dependent response function of the PADC detectors to account for the spectral changes in the neutron fluence. The resulting total calibration factors are 0.76 for a photon beam (in- and out-of-field), 1.00 (in-field) and 0.84 (out-of-field) for an active proton beam and 1.05 (in-field) and 0.91 (out-of-field) for a passive proton beam, respectively. The uncertainty for neutron dose measurements using this field calibration method is less than 40%. The extended calibration procedure presented in this work showed that it is possible to use PADC track etch detectors for measurements of local neutron dose equivalent inside anthropomorphic phantoms by accounting for spectral changes in the neutron fluence.

Hälg, Roger A.; Besserer, Jürgen; Boschung, Markus; Mayer, Sabine; Clasie, Benjamin; Kry, Stephen F.; Schneider, Uwe

2012-12-01

369

Radiation dose evaluation in 3D rotation angiography and cone-beam computed tomography with a flat panel detector.  

PubMed

The aim of this study was to evaluate radiation dose in patients undergoing three-dimensional rotation angiography (3DRA) and cone-beam computed tomography (CBCT) using a flat panel detector (FPD). Radiation doses were measured for angiography equipment using small silicon-photodiode dosimeters that were implanted in various positions in tissues and organs within an anthropomorphic phantom of a standard Japanese adult male. Output signals from the dosimeters were read out on a computer, from which organ and effective doses were calculated according to guidelines published in International Commission on Radiological Protection Publication 103. Lens doses and effective doses obtained in this study were 1.6 mGy and 0.13 mSv for 3DRA, 20 mGy and 1.7 mSv for CBCT (normal mode). 3DRA provided substantial lens doses and effective dose reduction, which were 8% of the doses in CBCT (normal mode). PMID:25055944

Seguchi, Shigenobu; Saijou, Takaya; Ishikawa, Yoshinobu; Koyama, Shuji

2014-07-01

370

Investigation of the Charge Collection Efficiency of CdMnTe Radiation Detectors  

SciTech Connect

This paper presents the growth, fabrication and characterization of indium-doped cadmium manganese telluride (CdMnTe) crystals grown by the vertical Bridgman technique. The 10 x 10 x 1.9 mm{sup 3} samples have been fabricated, and the charge collection properties of the CdMnTe detectors have been measured. Alpha-particle spectroscopy measurements have yielded an average charge collection efficiency approaching 100%. Ion beam induced charge (IBIC) measurements have been performed by raster scanning focused 5.5 MeV {sup 4}He beams onto the detectors. Spatially resolved charge collection efficiency maps have been produced for a range of detector bias voltages. Inhomogeneities in the charge transport of the CdMnTe crystals have been associated with chains of Te inclusions within the detector bulk, and the reduction in charge collection efficiency in their locality has been quantified. It has been shown that the role of Te inclusions in degrading charge collection is reduced with increasing values of bias voltage. IBIC measurements for a range of low biases have highlighted the evolution of the charge collection uniformity across the detectors.

Bolotnikov A.; Rafiei, R.; Boardman, D.; Sarbutt, A.; Prokopovich, A.; Kim, K.; Reinhard, M.I.; James, R.B.

2012-06-01

371

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

372

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

373

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

374

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

375

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

376

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

E-print Network

Scope Using the circuit of Figure 5 as a model~ two circuits for a practical amplifier detector unit are advanced by the author. One type of amplifier detector unit is shown in Figure 7 ~ Resistor Rs sets the proper bias on the test diode and Rg... adjusts the proper bias on the transistor. A large degeneration of signal is inherent in this type of circuit since some of the current from the equivalent pulse generator in the diode is shunted through Rs and the battery, Eb. PNP Figure 7 Amplif...

Willis, Giles Whitehurst

2012-06-07

377

Measuring Neutrons and Gamma Rays on Mars - The Mars Science Laboratory Radiation Assessment Detector MSL/RAD  

NASA Astrophysics Data System (ADS)

The Mars Science Laboratory (MSL) missions Radiation Assessment Detector (RAD) will measure the radiation environment on the Martian surface. One of the difficult measurements is that of the neutral radiation component consisting of neutrons and gamma rays. Different from Earth, this neutral component contributes substantially to the total dose on the planetary surface, principally because the Martian atmosphere is so thin. The RAD instrument is capable of measuring neutral particles through a combination of sensitive anti-coincidence and organic and inorganic scintillator materials. In this work, we will explain how RAD will measure the neutral particle radiation on Mars and compare with calibration results. The problem of inverting measured neutron and gamma data is a non-trivial task. For all inversions, one generally assumes that the measurement process can be described by a system of linear equations, A ?c{f} = ?c{z}, where the matrix A describes the instrument response function (IRF), ?c{f} the underlying, but unknown, ``real'' physical parameters, and ?c{z} the measured data. The inversion of this deceptively simple-looking set of equations is in fact a key example of an ill-posed or inverse problem. Such problems are notoriously difficult to solve.

Wimmer-Schweingruber, R. F.; Martin, C.; Kortmann, O.; Boehm, E.; Kharytonov, A.; Ehresmann, B.; Hassler, D. M.; Zeitlin, C.; Rad Team

2010-12-01

378

Novel mm-wave and THz radiation active imaging system based on glow discharge detector (GDD) pixel  

NASA Astrophysics Data System (ADS)

A novel imaging system for mm wavelength and THz radiation is presented in this paper. The imaging system is based upon an inexpensive neon indicator lamp or glow discharge detector (GDD) that serves as a pixel in a focal plane array (FPA). It was shown in previous investigations that inexpensive neon indicator lamp GDDs are quite sensitive to mm wavelength and THz radiation. The diameter of the GDD lamp is 6 mm and thus the FPA can be diffraction limited. Using such neon lamps we realize a 4X4 FPA. We used a Polyethylene lens to focus the radiation on the FPA. First imaging results of the novel mm-wave and THz imaging system are presented here. They images are of decent quality. Increasing the resolution of the FPA to 8X8 or 16X16 will improve significantly the quality of the photos in the mm-wave and THz radiation. Our goal is to construct a 128X128 imaging system using the GDD technology.

Kopeika, N. S.; Abramovich, A.; Rozban, D.

2008-10-01

379

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

380

Recent results from the CERN RD39 Collaboration on super-radiation hard cryogenic silicon detectors for LHC and LHC upgrade  

NASA Astrophysics Data System (ADS)

The CERN RD39 Collaboration is developing super-radiation hard cryogenic Si detectors for applications in experiments of the LHC and the future LHC Upgrade. Radiation hardness up to the fluence of 10 16 n eq/cm 2 is required in the future experiments. Significant improvement in the radiation hardness of silicon sensors has taken place during the past years. However, 10 16 n eq/cm 2 is well beyond the radiation tolerance of even the most advanced semiconductor detectors made by commonly adopted technologies. Furthermore, at this radiation load the carrier trapping will limit the charge collection depth to the range of 20-30 ?m regardless of the depletion depth. The key of our approach is freezing the trapping that affects Charge Collection Efficiency (CCE).

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

2004-12-01

381

Scintillation of liquid xenon and its application to nuclear radiation detectors  

Microsoft Academic Search

To understand the superiority of liquid xenon as detector medium, at first, the scintillation mechanism of liquid rare gases is explained and the absolute scintillation yield in liquid xenon is estimated and then the decay shapes of scintillation lights from liquid xenon, which are faster than those of scintillation lights from crystal scintillators recently developed, are summarized. In addition, only

T. Doke

2005-01-01

382

Scintillation of liquid xenon and its application to nuclear radiation detectors  

Microsoft Academic Search

We review the scintillation mechanism of liquid rare gases and estimate the absolute scintillation yield of liquid xenon in order to understand the superiority of liquid xenon as a detector medium. The decays of scintillation light from liquid xenon, which are faster than those of scintillation light from crystal scintillators, are summarized. New photomultipliers with high quantum efficiency that can

Tadayoshi Doke

2006-01-01

383

Radiation Dose from Single-Heartbeat Coronary CT Angiography Performed with a 320–Detector Row Volume Scanner1  

PubMed Central

Purpose: To determine radiation doses from coronary computed tomographic (CT) angiography performed by using a 320–detector row volume scanner and evaluate how the effective dose depends on scan mode and the calculation method used. Materials and Methods: Radiation doses from coronary CT angiography performed by using a volume scanner were determined by using metal-oxide–semiconductor field-effect transistor detectors positioned in an anthropomorphic phantom physically and radiographically simulating a male or female human. Organ and effective doses were determined for six scan modes, including both 64-row helical and 280-row volume scans. Effective doses were compared with estimates based on the method most commonly used in clinical literature: multiplying dose-length product (DLP) by a general conversion coefficient (0.017 or 0.014 mSv·mGy?1·cm?1), determined from Monte Carlo simulations of chest CT by using single-section scanners and previous tissue-weighting factors. Results: Effective dose was reduced by up to 91% with volume scanning relative to helical scanning, with similar image noise. Effective dose, determined by using International Commission on Radiological Protection publication 103 tissue-weighting factors, was 8.2 mSv, using volume scanning with exposure permitting a wide reconstruction window, 5.8 mSv with optimized exposure and 4.4 mSv for optimized 100-kVp scanning. Estimating effective dose with a chest conversion coefficient resulted in a dose as low as 1.8 mSv, substantially underestimating effective dose for both volume and helical coronary CT angiography. Conclusion: Volume scanning markedly decreases coronary CT angiography radiation doses compared with those at helical scanning. When conversion coefficients are used to estimate effective dose from DLP, they should be appropriate for the scanner and scan mode used and reflect current tissue-weighting factors. © RSNA, 2010 PMID:20177085

Elliston, Carl D.; Arai, Andrew E.; Chen, Marcus Y.; Mather, Richard; Pearson, Gregory D. N.; DeLaPaz, Robert L.; Nickoloff, Edward; Dutta, Ajoy; Brenner, David J.

2010-01-01

384

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

385

A Radiation-Hard Silicon Drift Detector Array for Extraterrestrial Element Mapping  

NASA Technical Reports Server (NTRS)

Measurement of x-rays from the surface of objects can tell us about the chemical composition Absorption of radiation causes characteristic fluorescence from material being irradiated. By measuring the spectrum of the radiation and identifying lines in the spectrum, the emitting element (s) can be identified. This technique works for any object that has no absorbing atmosphere and significant surface irradiation : Our Moon, the icy moons of Jupiter, the moons of Mars, the planet Mercury, Asteroids and Comets

Gaskin, Jessica; Chen, Wei; De Geronimo, Gianluigi; Keister, Jeff; Li, Shaouri; Li, Zhen; Siddons, David P.; Smith, Graham

2011-01-01

386

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

387

Monte Carlo simulation of beta radiation response function for semiconductor Si detector  

NASA Astrophysics Data System (ADS)

This paper describes the modeling of the Passivated Implanted Planar Silicon (PIPS) detector for the beta particles response function simulations with the MCNP-5 code. The simulated and measured energy response functions were compared and a good agreement was found in the entire range of energies. The verified model of a PIPS detector was applied in a non-destructive method that determines the activity of beta emitters in the sample with a known geometry and atomic number densities. The procedure for the identification of beta emitters in the samples was also described. Finally, the application of the proposed method for the determination of 137Cs and 90Sr activity in water samples taken from the RA reactor spent fuel storage pools and from the paper filter taken from an air monitor operated during repackaging of spent fuel elements, was presented.

Gruji?, Selena; Miloševi?, Miodrag; Kozmidis-Luburi?, Uranija; Bikit, Ištvan

2011-10-01

388

Characterization of CdTe\\/n+Si Heterojunction Diodes for Nuclear Radiation Imaging Detectors  

Microsoft Academic Search

CdTe\\/n+-Si heterojunction diodes were fabricated and characterized for the development of gamma ray detectors. With the careful control of the growth parameters thick single crystal CdTe epilayers of high-crystalline quality were grown directly on the (211) Si substrates in a metalorganic vapor phase epitaxy. The heterojunction diode was fabricated by growing a 5 mum thick n-type CdTe buffer layer on

M. Niraula; K. Yasuda; K. Noda; K. Nakamura; I. Shingu; M. Yokota; M. Omura; S. Minoura; H. Ohashi; R. Tanaka; Y. Agata

2006-01-01

389

Characterization of CdTe\\/n+ Si Heterojunction Diodes for Nuclear Radiation Detectors  

Microsoft Academic Search

CdTe\\/n+-Si heterojunction diodes were fabricated and characterized for the development of gamma ray detectors. With the careful control of the growth parameters thick single crystal CdTe epilayers of high-crystalline quality were grown directly on the (211) Si substrates in a metalorganic vapor phase epitaxy. The heterojunction diode was fabricated by growing a 5 mum thick n-type CdTe buffer layer on

M. Niraula; K. Yasuda; K. Noda; K. Nakamura; I. Shingu; M. Yokota; M. Omura; S. Minoura; H. Ohashi; R. Tanaka; Y. Agata

2007-01-01

390

Amorphous silicon\\/crystalline silicon heterojunctions for nuclear radiation detector applications  

Microsoft Academic Search

Results on the characterization of the electrical properties of amorphous silicon films for the three different growth methods, RF sputtering, PECVD, and LPCVD are reported. The performance of these a-Si films as heterojunctions on high resistivity p-type and n-type crystalline silicon is examined by measuring the noise, leakage current and the alpha particle response of 5 mm diameter detector structures.

J. T. Walton; W. S. Hong; P. N. Luke; N. W. Wang; F. P. Ziemba

1997-01-01

391

Amorphous silicon\\/crystalline silicon heterojunctions for nuclear radiation detector applications  

Microsoft Academic Search

Results on the characterization of the electrical properties of amorphous silicon films for the three different growth methods, RF sputtering, PECVD, and LPCVD are reported. The performance of these a-Si films as heterojunctions on high resistivity p-type and n-type crystalline silicon is examined by measuring the noise, leakage current and the alpha particle response of 5 mm diameter detector structures.

J. T. Walton; W. S. Hong; P. N. Luke; N. W. Wang; F. P. Ziemba

1996-01-01

392

Effects of surface Processing on the performance of Cd1-xZnxTe radiation detectors  

Microsoft Academic Search

The effects of polishing on the electron mobility-lifetime product of a detector-grade Cd1-xZnxTe (CZT) crystal is reported. The two surfaces of the crystal were deposited with Au layers and illuminated with subband light. A direct current (dc) photocurrent technique was used to measure the electron mobility-lifetime product as a function of the illuminating power. The measured dependence of the electron

Y. Cui; M. Groza; A. Burger; R. B. James

2004-01-01

393

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

394

An InGaAs detector based radiation thermometer and fixed-point blackbodies for temperature scale realization at NIM  

SciTech Connect

In this paper, we describe an InGaAs detector based radiation thermometer (IRT) and new design of fixed-point blackbodies, including Sn, Zn, Al and Cu, for the establishment of a temperature scale from 200 °C to 1085 °C at the National Institute of Metrology of China. The construction and calibration of the IRT with the four fixed-point blackbodies are described. Characteristics of the IRT, such as the size-of-source effect, the amplifier performance and its stability are determined. The design of the four fixed-points, with 10 mm diameter of aperture and 0.9999 emissivity, is described. The uncertainty of the scale realization is elaborated.

Hao, X.; Yuan, Z.; Wang, J.; Lu, X. [Division of Thermometry and Materials Evaluation, National Institute of Metrology, Beijing, China, 100013 (China)] [Division of Thermometry and Materials Evaluation, National Institute of Metrology, Beijing, China, 100013 (China)

2013-09-11

395

SPECTROSCOPIC INVESTIGATION OF (NH4)2S TREATED GaSeTe FOR RADIATION DETECTOR APPLICATIONS  

SciTech Connect

The surface of the layered III-VI chalcogenide semiconductor GaSeTe was treated with (NH{sub 4}){sub 2}S at 60 C to modify the surface chemistry and determine the effect on transport properties. Room temperature photoluminescence (PL) measurements were used to assess the effect of the (NH{sub 4}){sub 2}S treatment on surface defect states. Evaluation of the subsequent surface chemistry was performed with high-resolution core-level photoemission measurements. Metal overlayers were deposited on the (NH{sub 4}){sub 2}S treated surfaces and the I-V characteristics were measured. The measurements were correlated to understand the effect of (NH{sub 4}){sub 2}S modification of the interfacial electronic structure with the goal of optimizing the metal/GaSeTe interface for radiation detector devices.

Nelson, A; Laurence, T; Conway, A; Behymer, E; Sturm, B; Voss, L; Nikolic, R; Payne, S; Mertiri, A; Pabst, G; Mandal, K; Burger, A

2009-08-04

396

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

397

Radiation-induced point- and cluster-related defects with strong impact on damage properties of silicon detectors  

NASA Astrophysics Data System (ADS)

This work focuses on the investigation of radiation-induced defects responsible for the degradation of silicon detector performance. Comparative studies of the defects induced by irradiation with 60Co-? rays, 6 and 15 MeV electrons, 23 GeV protons and reactor neutrons revealed the existence of point defects and cluster-related centers having a strong impact on damage properties of Si diodes. The detailed relation between the "microscopic" reasons as based on defect analysis and their "macroscopic" consequences for detector performance is presented. In particular, it is shown that the changes in the Si device properties (depletion voltage and leakage current) after exposure to high levels of 60Co-? doses can be completely understood by the microscopically investigated formation of two point defects, a deep acceptor and a shallow donor, both depending strongly on the oxygen concentration in the silicon bulk. Specific for hadron irradiation are the annealing effects which decrease (increase) the originally observed damage effects as seen by the changes of the depletion voltage and these effects are known as "beneficial" and "reverse" annealing, respectively. A group of three cluster-related defects, revealed as deep hole traps, proved to be responsible specifically for the reverse annealing. Their formation is not affected by the oxygen content or silicon growth procedure suggesting that they are complexes of multi-vacancies located inside extended disordered regions.

Pintilie, Ioana; Lindstroem, Gunnar; Junkes, Alexandra; Fretwurst, Eckhart

2009-11-01

398

Measurement of the efficiency of the pattern recognition of tracks generated by ionizing radiation in a TIMEPIX detector  

NASA Astrophysics Data System (ADS)

A hybrid silicon pixelated TIMEPIX detector (256 × 256 square pixels with a pitch of 55 ?m) operated in Time Over Threshold (TOT) mode was exposed to radioactive sources and protons after Rutherford Backscattering on a thin gold foil of protons beams delivered by the Tandem Accelerator of the Montreal University. Simultaneous exposure of TIMEPIX to radioactive sources and to protons beams on top of the radioactive sources allowed measurements with different mixed radiation fields of protons, alpha-particles, photons and electrons. All measurements were performed in vacuum. The comparison of the experimental activities (determined from the measurement of the number of tracks left in the device by incoming particles) of the radioactive sources with their expected activities allowed the test of the device efficiency for track recognition. The efficiency of track recognition of incident protons of different energies as a function of the incidence angle was measured. The cluster size left by protons in the device was measured as a function of their incident energy at normal and large (75°) incident angles. The operation of TIMEPIX in TOT mode has allowed a 3D mapping of the charge spreading effect in the whole volume of the silicon sensor. The results of the present measurements demonstrate the TIMEPIX capability of differentiating between different types of particles species from mixed radiation fields and measuring their energy deposition. Single track analysis gives a good precision (significantly better than the 55 ?m size of one detector pixel) on the coordinates of the impact point of protons with normal incidence interacting in the TIMEPIX silicon layer.

Asbah, N.; Leroy, C.; Pospisil, S.; Soueid, P.

2014-05-01

399

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

400

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

SciTech Connect

Diamond exhibits many properties such as an outstanding radiation hardness and fast response time both important to design detectors working in extremely radioactive environments. Among the many applications these devices can be used for, there is the development of a fast and radiation hard neutron detector for the next generation of fusion reactors, such as the International Thermonuclear Experimental Reactor project, under construction at Cadarache in France. A technology to routinely produce electronic grade synthetic single crystal diamond detectors was recently developed by our group. One of such detectors, with an energy resolution of 0.9% as measured using an {sup 241}Am{alpha} particle source, has been heavily irradiated with 14.8 MeV neutrons produced by the Frascati Neutron Generator. The modifications of its spectroscopic properties have been studied as a function of the neutron fluence up to 2.0x10{sup 14} n/cm{sup 2}. In the early stage of the irradiation procedure an improvement in the spectroscopic performance of the detector was observed. Subsequently the detection performance remains stable for all the given neutron fluence up to the final one thus assessing a remarkable radiation hardness of the device. The neutron damage in materials has been calculated and compared with the experimental results. This comparison is discussed within the nonionizing energy loss (NIEL) hypothesis, which states that performance degradation is proportional to NIEL.

Pillon, M.; Angelone, M.; Aielli, G. [Associazione EURATOM-ENEA sulla Fusione, Centro Ricerche Frascati, Via E. Fermi 45, I-00044 Frascati, Roma (Italy); Almaviva, S.; Marinelli, Marco; Milani, E.; Prestopino, G.; Tucciarone, A.; Verona, C.; Verona-Rinati, G. [Dipartimento di Ingegneria Meccanica, Universita di Roma 'Tor Vergata', Via del Politecnico 1, I-00133, Roma (Italy)

2008-09-01

401

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

402

Evaluation of real-time digital pulse shapers with various HPGe and silicon radiation detectors  

NASA Astrophysics Data System (ADS)

Real-time digital pulse shaping techniques allow synthesis of pulse shapes that have been difficult to realize using the traditional analog methods. Using real-time digital shapers, triangular/trapezoidal filters can be synthesized in real time. These filters exhibit digital control on the rise time, fall time, and flat-top of the trapezoidal shape. Thus, the trapezoidal shape can be adjusted for optimum performance at different distributions of the series and parallel noise. The trapezoidal weighting function (WF) represents the optimum time-limited pulse shape when only parallel and series noises are present in the detector system. In the presence of 1/ F noise, the optimum WF changes depending on the 1/ F noise contribution. In this paper, we report on the results of the evaluation of new filter types for processing signals from CANBERRA high purity germanium (HPGe) and passivated, implanted, planar silicon (PIPS) detectors. The objective of the evaluation is to determine improvements in performance over the current trapezoidal (digital) filter. The evaluation is performed using a customized CANBERRA digital signal processing unit that is fitted with new FPGA designs and any required firmware modifications to support operation of the new filters. The evaluated filters include the Cusp, one-over-F (1/ F), and pseudo-Gaussian filters. The results are compared with the CANBERRA trapezoidal shaper.

Menaa, N.; D'Agostino, P.; Zakrzewski, B.; Jordanov, V. T.

2011-10-01

403

Overview of the recent activities of the RD50 collaboration on radiation hardening of semiconductor detectors for the sLHC  

NASA Astrophysics Data System (ADS)

The RD50 collaboration has been exploring the development of radiation hard semiconductor devices for very high-luminosity colliders since 2002. The target fluence to qualify detectors set by the anticipated dose for the innermost tracking layers of the future upgrade of the CERN large hadron collider (LHC) is 10 16 1 MeV neutron equivalent (n eq) cm -2. This is about an order of magnitude higher than the maximum dose for the most exposed silicon detectors in the current machine. RD50 investigates the radiation hardening of silicon sensors from many angles: improvement of the intrinsic tolerance of the substrate material, optimisation of the readout geometry and study of novel design of detectors. A review of some of the recent activities within RD50 is here presented.

Casse, Gianluigi

2009-01-01

404

Research Update: Reactively sputtered nanometer-thin ZrN film as a diffusion barrier between Al and boron layers for radiation detector applications  

NASA Astrophysics Data System (ADS)

In this paper, optimization of the process flow for PureB detectors is investigated. Diffusion barrier layers between a boron layer and the aluminum interconnect can be used to enhance the performance and visual appearance of radiation detectors. Few nanometers-thin Zirconium Nitride (ZrN) layer deposited by reactive sputtering in a mixture of Ar/N2, is identified as a reliable diffusion barrier with better fabrication process compatibility than others. The barrier properties of this layer have been tested for different boron layers deposited at low and high temperatures with extensive optical microscopy analyses, electron beam induced current, SEM, and electrical measurements. This study demonstrated that spiking behavior of pure Al on Si can be prevented by the thin ZrN layer thus improving the performance of the radiation detectors fabricated using boron layer.

Golshani, Negin; Mohammadi, V.; Schellevis, H.; Beenakker, C. I. M.; Ishihara, R.

2014-10-01

405

Research Update: Reactively sputtered nanometer-thin ZrN film as a diffusion barrier between Al and boron layers for radiation detector applications  

SciTech Connect

In this paper, optimization of the process flow for PureB detectors is investigated. Diffusion barrier layers between a boron layer and the aluminum interconnect can be used to enhance the performance and visual appearance of radiation detectors. Few nanometers-thin Zirconium Nitride (ZrN) layer deposited by reactive sputtering in a mixture of Ar/N{sub 2}, is identified as a reliable diffusion barrier with better fabrication process compatibility than others. The barrier properties of this layer have been tested for different boron layers deposited at low and high temperatures with extensive optical microscopy analyses, electron beam induced current, SEM, and electrical measurements. This study demonstrated that spiking behavior of pure Al on Si can be prevented by the thin ZrN layer thus improving the performance of the radiation detectors fabricated using boron layer.

Golshani, Negin, E-mail: negingolshani@gmail.com; Mohammadi, V.; Schellevis, H.; Beenakker, C. I. M.; Ishihara, R. [ECTM, DIMES, Faculty of Electrical Engineering (EWI), Delft University of Technology (TU Delft), Feldmannweg 17, P.O. Box 5053, 2628 CT Delft (Netherlands)

2014-10-01

406

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

407

A nuclear radiation detector system with integrated readout for SPECT\\/MR small animal imaging  

Microsoft Academic Search

We have developed and constructed an MR-compatible single photon emission computed tomography (SPECT) system for small animal molecular imaging applications. The system consists of identical radiation imaging modules and a multi-pinhole collimator sleeve. The modular design results in a very compact system which allows for easy insertion into state-of-the-art small animal MRI systems. This development leads to a multi-modality system

Suleyman Azman; J. Gjaerum; D. Meier; L. T. Muftuler; G. Maehlum; O. Nalcioglu; B. E. Patt; B. Sundal; M. Szawlowski; B. M. W. Tsui; D. J. Wagenaar; Yuchuang Wang

2007-01-01

408

Performances of operational amplifiers in front-end electronics for nuclear radiation detectors  

Microsoft Academic Search

Operational amplifiers in charge sensitive configuration are an attractive solution for front-end electronics in cost-sensitive radiation detection systems. The noise performances of several JFET input operational amplifiers were tested in a charge-sensitive configuration. Some rather old devices reached noise performances low enough for detection of X and gamma rays in applications where extreme energy resolution is not required as, for

A. Cerizza; A. Fazzi; V. Varoli

2004-01-01

409

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

410

Detector absorptivity measuring method and apparatus  

NASA Technical Reports Server (NTRS)

A method and apparatus for measuring the absorptivity of a radiation detector by making the detector an integral part of a cavity radiometer are described. By substituting the detector for the surface of the cavity upon which the radiation first impinges a comparison is made between the quantity of radiation incident upon the detector and the quantity reflected from the detector. The difference between the two is a measurement of the amount of radiation absorbed by the detector.

Sheets, R. E. (inventor)

1976-01-01

411

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

412

Radiation effect on positronium formation in solid state nuclear track detector.  

PubMed

The effect of alpha-particles on CR-39, a material used in solid state nuclear track detectors (SSNTDs), has been investigated using the positron annihilation lifetime (PAL) technique. The samples were irradiated using a (238)Pu alpha-source of energy ranging from 1 to 5 MeV and with different doses ranging from 0 to 57.87 mGy. The ortho-positronium (o-Ps) lifetime, tau(3), shows a slight increase as the irradiation dose increases, while a rapid change in the o-Ps intensity, I(3) at 10 mGy was found. In addition, the PAL parameters (tau(3), I(3)) have been studied as a function of the energy of alpha-particles. The obtained results indicate that the o-Ps lifetime increases slightly with increasing energy of the alpha-particle. On the other hand, the o-Ps intensity decreases exponentially with increasing alpha-particle energy, plateaus, and finally increases. The data show that the track diameter increases with decreasing energy of the alpha-particle, while the track density increases with increasing the irradiation dose. A correlation between the track diameter and the o-Ps hole diameter was observed. PMID:17049258

Mohamed, Hamdy F M; Abd El-Hady, M; Abdel-Hady, E E

2007-03-01

413

Improved neutron radiation hardness for Si detectors: application of low resistivity starting material and\\/or manipulation of Neff by selective filling of radiation-induced traps at low temperatures  

Microsoft Academic Search

Radiation-induced electrical changes in both space charge region (SCR) of Si detectors and bulk material (BM) have been studied for samples of diodes and resistors made on Si materials with different initial resistivities. The space charge sign inversion fluence (? inv) has been found to increase linearly with the initial doping concentration (the reciprocal of the resistivity), which gives improved

B. Dezillie; Z. Li; V. Eremin; M. Bruzzi; S. Pirollo; S. U. Pandey; C. J. Li

1999-01-01

414

From Vacuum Fluctuations to Radiation: Accelerated Detectors and Black Holes.(2)  

E-print Network

The energy and particle fluxes emitted by an accelerated two level atom are analysed in detail. It is shown both perturbatively and non perturbatively that the total number of emitted photons is equal to the number of transitions characterizing thermal equilibrium thereby confirming that each internal transition is accompanied by the emission of a Minkowski quantum. The mean fluxes are then decomposed according to the final state of the atom and the notion of conditional flux is introduced. This notion is generalized so as to study the energy content of the vacuum fluctuations that induce the transitions of the accelerated atom. The physical relevance of these conditional fluxes is displayed and contact is made with the formalism of Aharonov et al. The same decomposition is then applied to isolate, in the context of black hole radiation, the energy content of the particular vacuum fluctuations which are converted into on mass shell quanta. It is shown that initially these fluctuations are located around the light like geodesic that shall generate the horizon and have exponentially large energy densities. Upon exiting from the star they break up into two pieces. The external one is red shifted and becomes an on mass shell quantum, the other, its ''partner", ends up in the singularity. We avail ourselves of this analysis to study back reaction effects to the production of a single quantum.

S. Massar; R. Parentani

1995-02-10

415

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

416

Research and development of a Mini-RICH detector with a gas radiator as a first step towards a CBM-RICH prototype  

NASA Astrophysics Data System (ADS)

The Compressed Baryonic Matter (CBM) Experiment is planned to be installed at a future accelerator facility, SIS 100/300 of FAIR (Facility for Antiproton and Ion Research), GSI (Gesellschaft für SchwerIonenforschung) to study nuclear matter under extreme conditions with a high baryon density. A Ring Imaging Cherenkov (RICH) detector is now being developed for electron identification at p e < 8 GeV/ c, well separated from pions. In order to optimize the physics performance of the CBM-RICH detector and to investigate different gas radiators, we developed a mini-RICH detector with a gas system as a first prototype and tested it with the p e ? 60 MeV/c electron beam at the Pohang Accelerator Laboratory (PAL).

Yi, Jungyu; Choi, Kyungeon; Kim, Junghan; Lee, Hayoung; Son, Chang Wook; Yoo, In-Kwon

2012-10-01

417

Pion-to-proton ratio for unaccompanied high-energy cosmic-ray hadrons at mountain altitude using transition-radiation detector  

NASA Astrophysics Data System (ADS)

A transition-radiation (TR) detector, consisting of 24 modules of styrofoam radiators and multiwire proportional chambers, and an ionization calorimeter have been used to measure the pion-to-proton ratio among the unaccompanied cosmic-ray hadrons at a mountain altitude of 730 g cm-2. Using the characteristics of the TR detector obtained from calibrations with particle beams at accelerators, the ?p ratio has been determined for cosmic-ray hadrons as ?p=0.96+/-0.15 for hadron energy = 400-800 GeV, and ?p=0.45+/-0.25 for energy > 800 GeV. Monte Carlo simulations of hadron cascades in the atmosphere using the approximate criterion of unaccompaniment suggest that the observed ?p ratio as well as the previously reported neutral-to-charge ratio can be understood by assuming a value of about 13 for the charge exchange in nucleon-air-nucleus inelastic interactions at energies above 400 GeV.

Ellsworth, R. W.; Ito, A. S.; MacFall, J. R.; Siohan, F.; Streitmatter, R. E.; Tonwar, S. C.; Viswanath, P. R.; Yodh, G. B.

1983-05-01

418

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

419

Study of localised radiation damage to PIPS detectors by a scanning ion microprobe: Measured effects and the consequences for STIM analysis  

Microsoft Academic Search

Radiation damage effects in a PIPS particle detector have been studied by direct irradiation with a 4 MeV He+ focused ion beam, using the Eindhoven scanning ion microprobe set-up. This set-up enables extreme sensitivity and accuracy in pulse-height measurement. Pulse-height dependence on ion dose and the lateral variations of pulse-height response after damaging were studied, for different bias voltages. Pulse

D. P. L. Simons; A. J. H. Maas; P. H. A. Mutsaers; M. J. A. de Voigt

1997-01-01

420

Radiation hard blocked tunneling band GaAs AlGaAs superlattice long wavelength infrared detectors  

Microsoft Academic Search

We have developed a novel multiple quantum well (MQW) long wavelength infrared (LWIR) detector which can operate in a photovoltaic detection mode with an intrinsic event discrimination (IED) capability. The detector was constructed using the GaAsAlGaAs MQW technology to form a blocked tunneling band superlattice structure with a 10.2 micron wavelength and 2.2 micron bandwidth. The detector exhibited Schottky junction

C. S. Wu; C. P. Wen; P. Reiner; C. W. Tu; H. Q. Hou

1996-01-01

421

An XPS study of bromine in methanol etching and hydrogen peroxide passivation treatments for cadmium zinc telluride radiation detectors  

NASA Astrophysics Data System (ADS)

The performance of single crystal CdZnTe radiation detectors is dependent on both the bulk and the surface properties of the material. After single crystal fabrication and mechanical polishing, modification of the surface to remove damage and reduce the surface leakage current is generally achieved through chemical etching followed by a passivation treatment. In this work, CdZnTe single crystals have been chemically etched using a bromine in methanol (BM) treatment. The BM concentrations employed were 0.2 and 2.0 (v/v) % and exposure times varied between 5 and 120 s. Angle resolved XPS and sputter depth profiling has been employed to characterize the surfaces for the different exposure conditions. A Te rich surface layer was formed for all exposures and the layer thickness was found to be independent of exposure time. The enriched Te layer thickness was accurately determined by calibrating the sputter rate against a CdTe layer of known thickness. For BM concentrations of 0.2 (v/v) % and 2 (v/v) %, the Te layer thickness was determined to be 1.3 ± 0.2 and 1.8 ± 0.2 nm, respectively. The BM etched surfaces have subsequently been passivated in a 30 wt.% H2O2 solution employing exposure time of 15 s. The oxide layer thickness has been calculated using two standard XPS methodologies, based on the Beer-Lambert expression. The TeO2 thickness calculated from ARXPS data are slightly higher than the thickness obtained by the simplified Beer-Lambert expression. For BM exposures of 30-120 s followed by a passivation treatment of 30 wt. % H2O2 solution employing an exposure time 15 s, the ARXPS method gave an average TeO2 thickness value of 1.20 nm and the simplified Beer-Lambert expression gave an average thickness value of 0.99 nm.

Babar, S.; Sellin, P. J.; Watts, J. F.; Baker, M. A.

2013-01-01

422

GADRAS Detector Response Function.  

SciTech Connect

The Gamma Detector Response and Analysis Software (GADRAS) applies a Detector Response Function (DRF) to compute the output of gamma-ray and neutron detectors when they are exposed to radiation sources. The DRF is fundamental to the ability to perform forward calculations (i.e., computation of the response of a detector to a known source), as well as the ability to analyze spectra to deduce the types and quantities of radioactive material to which the detectors are exposed. This document describes how gamma-ray spectra are computed and the significance of response function parameters that define characteristics of particular detectors.

Mitchell, Dean J.; Harding, Lee; Thoreson, Gregory G; Horne, Steven M.

2014-11-01

423

Single charge carrier type sensing with a parallel strip pseudo-Frisch-grid CdZnTe semiconductor radiation detector  

E-print Network

Single charge carrier type sensing with a parallel strip pseudo-Frisch-grid CdZnTe semiconductor CdZnTe semiconductor detector that incorporates a parallel strip pseudo-Frisch-grid detector design produced by the moving free charge carriers can be measured by an external circuit. Shockley1 and Ramo2

He, Zhong

424

Measurement of terrestrial gamma radiation dose-rate (TGRD) level in soil samples from the district of Rembau, Malaysia, using high-purity Germanium detectors  

NASA Astrophysics Data System (ADS)

This study assesses the gamma radiation levels and associated dose rates from the naturally occurring radionuclides 232Th, 238U and 40K in soil samples collected from the district of Rembau, Malaysia using High-purity Germanium (HPGe) Detectors. A 105 measurement were performed on surface soil using NaI (Tl) gamma-ray detector with crystal size 1"x1", covering about 83% land of the Rembau district. The concentration of the naturally occurring radionuclides 232Th, 238U and 40K in soil samples collected were determined by using HPGe detector based on high-resolution gamma spectrometry system at Malaysia Nuclear Agency. The range of natural gamma radiation measured was from 114±14 nGy h?1 to 857±14 nGy h?1. The range of activity concentrations of U, Th and °K in soil from the studied areas varies from 151-401 Bq kg?1, 113-342 Bq kg?1 and 674-1526 Bq kg?1 with mean values of 245 Bq kg?1, 186 Bq kg?1 and 1152 Bq kg1 respectively. The mean values of terrestrial gamma radiation dose rate measured in Rembau district is 383±18 nGy h?1 compared to the Malaysian average is 92 nGy h?1 and world average is 59 nGy h?1 (UNSCEAR, 2000). The average annual dose from such terrestrial gamma radiation dose rates to an individual in Rembau district, assuming a tropical rural setting is estimated to be 0.78 mSv per year, which is considered to be within the normal range for doses from natural sources. An isodose map for the Rembau district has been plotted.

Norbani, N. E.; Abdullah Salim, N. A.; Rahman, A. T. Abdul

2014-11-01

425

Progress Towards High-Sensitivity Arrays of Detectors of Sub-mm Radiation using Superconducting Tunnel Junctions with Radio-Frequency Single-Electron Transistors  

NASA Technical Reports Server (NTRS)

The science drivers for the SPIRIT/SPECS missions demand sensitive, fast, compact, low-power, large-format detector arrays for high resolution imaging and spectroscopy in the far infrared and submillimeter. Detector arrays with 10,000 pixels and sensitivity less than 10(exp 20)-20 W/Hz(exp 20)0.5 are needed. Antenna-coupled superconducting tunnel junction detectors with integrated rf single-electron transistor readout amplifiers have the potential for achieving this high level of sensitivity, and can take advantage of an rf multiplexing technique when forming arrays. The device consists of an antenna structure to couple radiation into a small superconducting volume and cause quasiparticle excitations, and a single-electron transistor to measure currents through tunnel junction contacts to the absorber volume. We will describe optimization of device parameters, and recent results on fabrication techniques for producing devices with high yield for detector arrays. We will also present modeling of expected saturation power levels, antenna coupling, and rf multiplexing schemes.

Stevenson, T. R.; Hsieh, W.-T.; Li, M. J.; Stahle, C. M.; Wollack, E. J.; Schoelkopf, R. J.; Krebs, Carolyn (Technical Monitor)

2002-01-01

426

Large volume single crystal growth of cadmium zinc telluride with minimal secondary phases for room temperature radiation detector application  

NASA Astrophysics Data System (ADS)

Two major aspects of Cadmium Zinc Telluride (CdZnTe) crystal growth for room temperature radiation detection application namely tellurium rich second phase defects and single crystal yield have been addressed. Various approaches were considered towards the minimization of these defects both during growth and post growth thermal treatment in cadmium environment. Since the issue of retrograde solubility in CdZnTe pseudo binary alloy system causes tellurium precipitation, different cooling mechanisms were also devised to achieve minimal secondary phases. Some important and encouraging results were obtained relative to the size and distribution of secondary phases upon growing the crystal with different growth rate and different cooling rate of the crystal after growth. Thermomigration of tellurium were also observed while post processing samples in a temperature gradient, in (Cd,Zn) atmosphere. Results indicated orders of magnitude reduction on secondary phases at the expense of sample resistivity. Apart from the issue of secondary phases, CdZnTe also suffers from low single crystal yield. Since grain boundaries and twins are known to hinder the transport properties of charge carriers, it is necessary to have large single crystal volumes with good uniformity for better charge collection efficiency. In our crystal growth facility, single crystal volumes up to 25x25x20 mm3 have been grown using unseeded vertical Bridgman technique. However reproducibility has been a major issue as far as single crystal yield is concerned. In order to consistently produce large volume detector grade material, seeding was attempted in vertical Bridgman set up in which crystals are grown on top of another appropriately oriented seed crystal. Certain important requirements for successful seeded growth are partial melting of the seed from top, proper melt mixing before starting growth and maintaining a convex interface shape to promote outward grain growth. To achieve these conditions, extreme care was taken in designing our experimental set up. Seed crystals with various orientations have been used in different growths. Preliminary results on these growths indicate success in achieving partial seed melting and proper control on the thermal environment. The grown crystals exhibited large number of twins suggesting that the use of seed crystal with proper orientation is critical.

Swain, Santosh Kumar

427

Study of localised radiation damage to PIPS detectors by a scanning ion microprobe: Measured effects and the consequences for STIM analysis  

NASA Astrophysics Data System (ADS)

Radiation damage effects in a PIPS particle detector have been studied by direct irradiation with a 4 MeV He + focused ion beam, using the Eindhoven scanning ion microprobe set-up. This set-up enables extreme sensitivity and accuracy in pulse-height measurement. Pulse-height dependence on ion dose and the lateral variations of pulse-height response after damaging were studied, for different bias voltages. Pulse height was found to decrease linearly with ion dose and this could be observed after only a few ions per scan position, corresponding to a dose of 10 8/cm 2. Pulse-height loss was found to be restricted to damaged detector areas. Consequences of this pulse-height dependence on ion dose and scan position for the accuracy of STIM analyses are discussed.

Simons, D. P. L.; Maas, A. J. H.; Mutsaers, P. H. A.; de Voigt, M. J. A.

1997-07-01

428

Characteristics of a planar-type Cd0.9Zn0.1Te radiation detector grown by using the low-pressure bridgman method  

NASA Astrophysics Data System (ADS)

An indium-doped (7 ppm) Cd0.9Zn0.1Te single crystal for use in room-temperature radiation detectors has been grown using a low-pressure Bridgman (LPB) furnace at the Korea Atomic Research Institute. The single crystal has a (111) orientation and a high resistivity of ˜1 × 1012 ?·cm. In addition, the mobility-lifetime products of the electrons and hole are 4.2 × 10-4 cm2/V and 5 × 10-5 cm2/V, respectively. These values are simply derived by using a Hecht and a neural equation and 5 MeV alpha particles emitted from an 241Am alpha source. To characterize the Cd0.9Zn0.1Te grown by using the LPB method, we fabricated planar detectors with volume of 10 × 10 × 2.5 mm3 from a 2-inch-diameter Cd0.9Zn0.1Te ingot.

Jeong, Manhee; Kim, Han Soo; Kim, Young Soo; Ha, Jang Ho

2014-04-01

429

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

430

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

431

The development of a high count rate neutron flux monitoring channel using silicon carbide semiconductor radiation detectors  

NASA Astrophysics Data System (ADS)

In this dissertation, a fast neutron flux-monitoring channel, which is based on the use of SiC semiconductor detectors is designed, modeled and experimentally evaluated as a power monitor for the Gas Turbine Modular Helium Reactors. A detailed mathematical model of the SiC diode detector and the electronic processing channel is developed using TRIM, MATLAB and PSpice simulation codes. The flux monitoring channel is tested at the OSU Research Reactor. The response of the SiC neutron-monitoring channel to neutrons is in close agreement to simulation results. Linearity of the channel response to thermal and fast neutron fluxes, pulse height spectrum of the channel, energy calibration of the channel and the detector degradation in a fast neutron flux are presented. Along with the model of the neutron monitoring channel, a Simulink model of the GT-MHR core has been developed to evaluate the power monitoring requirements for the GT-MHR that are most demanding for the SiC diode power monitoring system. The Simulink model is validated against a RELAP5 model of the GT-MHR. This dyanamic model is used to simulate reactor transients at the full power and at the start up, in order to identify the response time requirements of the GT-MHR. Based on the response time requirements that have been identified by the Simulink model and properties of the monitoring channel, several locations in the central reflector and the reactor cavity are identified to place the detector. The detector lifetime and dynamic range of the monitoring channel at the detector locations are calculated. The channel dynamic range in the GT-MHR central reflector covers four decades of the reactor power. However, the detector does not survive for a reactor refueling cycle in the central reflector. In the reactor cavity, the detector operates sufficiently long; however, the dynamic range of the channel is smaller than the dynamic range of the channel in the central reflector.

Reisi Fard, Mehdi

432

Characterization of high-resistivity CdTe and Cd0.9Zn0.1Te crystals grown by Bridgman method for radiation detector applications  

NASA Astrophysics Data System (ADS)

CdTe and Cd0.9Zn0.1Te (CZT) crystals have been studied extensively for various applications including x- and ?-ray imaging and high energy radiation detectors. The crystals were grown from zone refined ultra-pure precursor materials using a vertical Bridgman furnace. The growth process has been monitored, controlled, and optimized by a computer simulation and modeling program developed in our laboratory. The grown crystals were thoroughly characterized after cutting wafers from the ingots and processed by chemo-mechanical polishing (CMP). The infrared (IR) transmission images of the post-treated CdTe and CZT crystals showed average Te inclusion size of ~10 ?m for CdTe and ~8 ?m for CZT crystal. The etch pit density was ? 5×104 cm-2 for CdTe and ? 3×104 cm-2 for CZT. Various planar and Frisch collar detectors were fabricated and evaluated. From the current-voltage measurements, the electrical resistivity was estimated to be ~ 1.5×1010 ?-cm for CdTe and 2-5×1011 ?-cm for CZT. The Hecht analysis of electron and hole mobility-lifetime products (??e and ??h) showed ??e = 2×10-3 cm2/V (??h = 8×10-5 cm2/V) and 3-6×10-3 cm2/V (??h = 4- 6×10-5 cm2/V) for CdTe and CZT, respectively. Detectors in single pixel, Frisch collar, and coplanar grid geometries were fabricated. Detectors in Frisch grid and guard-ring configuration were found to exhibit energy resolution of 1.4% and 2.6 %, respectively, for 662 keV gamma rays. Assessments of the detector performance have been carried out also using 241Am (60 keV) showing energy resolution of 4.2% FWHM.

Mandal, Krishna C.; Krishna, Ramesh M.; Pak, Rahmi O.; Mannan, Mohammad A.

2014-09-01

433

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

434

8. Particle detectors 8.1 Emulsions  

E-print Network

leave analyzable tracks. 8.2 Solid-state detectors Solid-state detectors come in different types, first, and the radiation hardness that make then ideally suited for the harsh radiation environment of satellites and high and one wishes the particle to be absorbed in the detector, then water may be a useful detector material

Pohl, Martin Karl Wilhelm

435

8. Particle detectors 8.1 Emulsions  

E-print Network

leave analyzable tracks. 8.2 Solid-state detectors Solid-state detectors come in different types, first, and the radiation hardness that make them ideally suited for the harsh radiation environment of satellites and high and one wishes the particle to be absorbed in the detector, then water may be a useful detector material

Pohl, Martin Karl Wilhelm

436

Ultraviolet detectors Photon detectors  

E-print Network

of aluminum gallium nitride (AlxGa1-xN)-based thin films varies as a function of x, with x ranging from 0 to 1Ultraviolet detectors Photon detectors Photoelectric Semiconductor Photoconductive Schottky barrier

437

Output correction factors for nine small field detectors in 6 MV radiation therapy photon beams: A PENELOPE Monte Carlo study  

SciTech Connect

Purpose: To determine detector-specific output correction factors,k{sub Q} {sub c{sub l{sub i{sub n}}}} {sub ,Q} {sub m{sub s{sub r}}} {sup f{sub {sup {sub c}{sub l}{sub i}{sub n}{sub {sup ,f{sub {sup {sub m}{sub s}{sub r}{sub ,}}}}}}}} in 6 MV small photon beams for air and liquid ionization chambers, silicon diodes, and diamond detectors from two manufacturers. Methods: Field output factors, defined according to the international formalism published byAlfonso et al. [Med. Phys. 35, 5179–5186 (2008)], relate the dosimetry of small photon beams to that of the machine-specific reference field; they include a correction to measured ratios of detector readings, conventionally used as output factors in broad beams. Output correction factors were calculated with the PENELOPE Monte Carlo (MC) system with a statistical uncertainty (type-A) of 0.15% or lower. The geometries of the detectors were coded using blueprints provided by the manufacturers, and phase-space files for field sizes between 0.5 × 0.5 cm{sup 2} and 10 × 10 cm{sup 2} from a Varian Clinac iX 6 MV linac used as sources. The output correction factors were determined scoring the absorbed dose within a detector and to a small water volume in the absence of the detector, both at a depth of 10 cm, for each small field and for the reference beam of 10 × 10 cm{sup 2}. Results: The Monte Carlo calculated output correction factors for the liquid ionization chamber and the diamond detector were within about ±1% of unity even for the smallest field sizes. Corrections were found to be significant for small air ionization chambers due to their cavity dimensions, as expected. The correction factors for silicon diodes varied with the detector type (shielded or unshielded), confirming the findings by other authors; different corrections for the detectors from the two manufacturers were obtained. The differences in the calculated factors for the various detectors were analyzed thoroughly and whenever possible the results were compared to published data, often calculated for different accelerators and using the EGSnrc MC system. The differences were used to estimate a type-B uncertainty for the correction factors. Together with the type-A uncertainty from the Monte Carlo calculations, an estimation of the combined standard uncertainty was made, assigned to the mean correction factors from various estimates. Conclusions: The present work provides a consistent and specific set of data for the output correction factors of a broad set of detectors in a Varian Clinac iX 6 MV accelerator and contributes to improving the understanding of the physics of small photon beams. The correction factors cannot in general be neglected for any detector and, as expected, their magnitude increases with decreasing field size. Due to the reduced number of clinical accelerator types currently available, it is suggested that detector output correction factors be given specifically for linac models and field sizes, rather than for a beam quality specifier that necessarily varies with the accelerator type and field size due to the different electron spot dimensions and photon collimation systems used by each accelerator model.

Benmakhlouf, Hamza, E-mail: hamza.benmakhlouf@karolinska.se [Department of Medical Physics, Karolinska University Hospital, SE-171 76 Stockholm, Sweden, and Department of Physics, Medical Radiation Physics, Stockholm University and Karolinska Institute, SE-171 76 Stockholm (Sweden)] [Department of Medical Physics, Karolinska University Hospital, SE-171 76 Stockholm, Sweden, and Department of Physics, Medical Radiation Physics, Stockholm University and Karolinska Institute, SE-171 76 Stockholm (Sweden); Sempau, Josep [Institut de Tècniques Energètiques, Universitat Politècnica de Catalunya, Diagonal 647, E-08028, Barcelona (Spain)] [Institut de Tècniques Energètiques, Universitat Politècnica de Catalunya, Diagonal 647, E-08028, Barcelona (Spain); Andreo, Pedro [Department of Physics, Medical Radiation Physics, Stockholm University and Karolinska Institute, SE-171 76 Stockholm (Sweden)] [Department of Physics, Medical Radiation Physics, Stockholm University and Karolinska Institute, SE-171 76 Stockholm (Sweden)

2014-04-15

438

Effect of electron transport properties on unipolar CdZnTe radiation detectors: LUND, spectrumplus and coplanar grid  

Microsoft Academic Search

Device simulations of (1) the laterally contacted-unipolar-nuclear detector (LUND), (2) the SpectrumPlus, (3) and the coplanar\\u000a grid made of Cd0.9Zn0.1Te (CZT) were performed for 137Cs irradiation by 662.15 keV gamma-rays. Realistic and controlled simulations of the gamma-ray interactions with the CZT material\\u000a were done using the MCNP4B2 Monte Carlo program, and the detector responses were simulated using the Sandia three-dimensional

E. Y. Lee; R. B. James

1999-01-01

439

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

Microsoft Academic Search

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 ¹³⁷Cs 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

Ralph B. James

2000-01-01

440

Effect of electron transport properties on unipolar CdZnTe radiation detectors: LUND, spectrumplus and coplanar grid  

Microsoft Academic Search

Device simulations of (1) the laterally contacted-unipolar-nuclear detector (LUND), (2) the SpectrumPlus, (3) and the coplanar grid made of Cd0.9Zn0.1Te (CZT) were performed for 137Cs 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

E. Y. Lee; R. B. James

1999-01-01

441

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

442

MCT infrafed detectors with close to radiatively limited performance at 240 K in the 3 5 µm band  

NASA Astrophysics Data System (ADS)

Results are reported on infrared photodiodes which have been designed to minimize the dark diffusion currents for operating temperatures above 200 K in the MWIR (3 5 µm) waveband. It is shown that by adjusting the doping and composition profiles, the dark currents due to Auger and contact diffusion mechanisms can be controlled leading to devices which are close to being radiatively limited. The radiatively-generated current has been calculated as a function of temperature from the measured spectral response and this indicates that the radiative contribution increases from about 53% at 240 K to 65% at 300K. In addition, it is shown that these internally-generated radiative currents can be reduced using negative luminescence. This result is the first experimental verification that the internally-generated radiative mechanism can contribute to the diffusion current.

Gordon, N. T.; Hall, R. S.; Jones, C. L.; Maxey, C. D.; Metcalfe, N. E.; Catchpole, R. A.; White, A. M.

2000-06-01

443

Optic detectors calibration for measuring ultra-high energy extensive air showers Cherenkov radiation by 532nm laser  

NASA Astrophysics Data System (ADS)

Calibration of a PMT matrix is crucial for the treatment of the data obtained with Cherenkov tracking detector. Furthermore, due to high variability of the aerosol abundance in the atmosphere depending on season, weather etc. A constant monitoring of the atmospheric transparency is required during the measurements. For this purpose, besides traditional methods, a station for laser atmospheric probing is used.

Knurenko, S. P.; Egorov, Yu. A.; Petrov, I. S.

2014-11-01