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1

RADIATION DETECTOR  

DOEpatents

A radiation detector of the type is described wherein a condenser is directly connected to the electrodes for the purpose of performing the dual function of a guard ring and to provide capacitance coupling for resetting the detector system.

Wilson, H.N.; Glass, F.M.

1960-05-10

2

Radiation detector  

DOEpatents

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

Fultz, B.T.

1980-12-05

3

Radiation detector  

DOEpatents

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

Fultz, Brent T. (Berkeley, CA)

1983-01-01

4

Tin Can Radiation Detector.  

ERIC Educational Resources Information Center

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

Crull, John L.

1986-01-01

5

Hand held radiation detector  

Microsoft Academic Search

A hand-held radiation detector is described for measuring localized radiation at extremely low levels, the detector comprising: a housing including two peripherally engaged, axially extending, tubular members, one of the members being entirely insulative, the other of the members being metallic; a radiation window at one end of the metallic tubular member, the window including a metallic portion in electrical

Wijangco

1984-01-01

6

RADIATION WAVE DETECTOR  

DOEpatents

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

Wouters, L.F.

1958-10-28

7

Absolute radiation detector  

NASA Astrophysics Data System (ADS)

An absolute radiation detector (a cryogenic radiometer) is being developed to replace the existing UK primary national standard cryogenic radiometer with an improved uncertainty. The cryogenic radiometer will be capable of measuring black body radiation and laser radiation with an uncertainty approaching 10 ppm. From these measurements it will be possible to determine the fundamental constant, the Stefan Boltzmann constant, confirming the radiometer as an absolute detector, and link this determination to the SI unit of luminous intensity, the candela. Thus detector and source based scales/standards will be tied to an invariant physical quantity ensuring their long-term stability.

Martin, John E.

1996-11-01

8

Underwater Radiation Detector.  

National Technical Information Service (NTIS)

A detector apparatus for differentiating between gamma and neutron radiation is provided. The detector includes a pair of differentially shielded Geiger-Mueller tubes. The first tube is wrapped in silver foil and the second tube is wrapped in lead foil. B...

L. W. Kruse R. P. McKnight

1984-01-01

9

Electromagnetic radiation detector  

DOEpatents

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

Benson, Jay L. (Albuquerque, NM); Hansen, Gordon J. (Albuquerque, NM)

1976-01-01

10

Radiation Detectors and Art  

NASA Astrophysics Data System (ADS)

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

Denker, Andrea

11

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

12

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

13

Ionizing radiation detector  

DOEpatents

An ionizing radiation detector is provided which is based on the principal 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, L.H.

1989-06-08

14

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

Agouridis, Dimitrios C. (Oak Ridge, TN)

1983-01-01

15

Semiconductor radiation detector  

SciTech Connect

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

16

Radiation heat loss detector  

SciTech Connect

In a radiation heat loss detector, radiation from an extended surface area is detected with a sensor having a wide field of view closely matching that of an associated camera. By simultaneously photographing the surface area of interest and detecting the radiation from that same area, a clear record is provided for future use. A wide band radiation sensor is used. Compensation for environmental radiation is made by first viewing the environment with the sensor and holding the sensed signal and then subtracting that signal from the flux detected when the sensor faces the extended surface area. The date and time are also recorded on the photograph. A sonar device positioned on the camera provides a distance indication which, with a known field of view, allows for a determination of the total flux from the surface area, a determination of convective heat losses from the surface and a correction for atmospheric absorption of the radiant energy.

Pompei, F.

1982-08-10

17

First infrared radiation detector  

SciTech Connect

The first in the world noncooled photon detector designed for the detection of infrared radiation of wave length 8-12 micrometers (optimized wave length 10.6 micrometers) has been manufactured in the Plasma Physics and Laser Microsynthesis Institute, in close cooperation with the Technical Military Academy. The father of the technology is Professor Piotrowski from the Technical Military Academy while the construction and idea of utilization of the new instrument stem from the Plasma Physics and Laser Microsynthesis Institute in Warsaw. The elaboration of a new and really sensational technology was the logical outcome of research work carried out in Poland on cadmium-mercury telluride. And it was just on the basis of that new semiconductor that the noncooled infrared radiation detector has been constructed.

Not Available

1984-03-01

18

Diamond radiation detectors II. CVD diamond development for radiation detectors  

SciTech Connect

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

Kania, D.R.

1997-05-16

19

Cadmium telluride photovoltaic radiation detector  

DOEpatents

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

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

1981-01-01

20

Detectors of thermal infrared radiation  

NASA Astrophysics Data System (ADS)

Some of the different types of detectors for thermal IR radiation are reviewed. Emphasis is placed on the ongoing trends to higher operating temperature and increasing array size. It is concluded that Hg(1-x)Cd(x)Te alloy, used in intrinsic photon detectors, is the principal material for first-generation thermal imaging systems and probably will retain this role in the next generation of both missile guidance systems and thermal imagers. Its future role may be threatened by PtSi Schottky barrier arrays or thermal detector arrays.

Elliott, C. T.

1988-01-01

21

Modern detectors for radiation monitors  

Microsoft Academic Search

The possibilities of using modern photon and neutron detectors for developing radiation monitors, specifically, LaBr3, Bi4Ge3O12, CdWO4, LiI, ZnO, Lu2SiO5(Ce), CdTe, and HgI2, microtubes from organic scintillators, nanomaterials, and detectors based on gaseous and solid-state electronic multipliers\\u000a are examined. A comparison is made of conventional detectors based on NaI(Tl) and CsI(Tl), plastic scintillators, and 3He counters. The advantages of the

A. V. Shumakov; A. S. Sviridov; S. V. Kolesnikov

2011-01-01

22

Flexible composite radiation detector  

SciTech Connect

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

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

2006-12-05

23

Radiation detectors as surveillance monitors  

SciTech Connect

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

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

1981-01-01

24

IC-compatible ionizing-radiation detector  

Microsoft Academic Search

A new type of MOS ionization dosimetry device, which offers several major advantages over present detectors, is described. This device is fabricated using radiation-hardened CMOS processing technology, allowing integration of the ionization detector with radiation-hardened integrated circuits. The detector can be used as part of a circuit element which either switches state at a precisely controlled radiation level or provides

W. R. Jr. Dawes; J. R. Schwank

1981-01-01

25

Radiation hardness studies of CVD diamond detectors  

Microsoft Academic Search

The inherent properties of diamond make it an ideal material for tracking detectors especially in the high rate, high radiation environments of future colliders such as the LHC. In order to survive in this environment, detectors must be radiation hard. We have constructed charged particle detectors using high quality CVD diamond and performed radiation hardness tests on them. The signal

C. Bauer; I. Baumann; C. Colledani; J. Conway; P. Delpierre; F. Djama; W. Dulinski; A. Fallou; K. K. Gan; R. S. Gilmore; E. Grigoriev; G. Hallewell; S. Han; T. Hessing; K. Honschied; J. Hrubec; D. Husson; H. Kagan; D. Kania; R. Kass; W. Kinnison; K. T. Knöpfle; M. Krammer; T. J. Llewellyn; P. F. Manfredi; L. S. Pan; H. Pernegger; M. Pernicka; R. Plano; V. Re; S. Roe; A. Rudge; M. Schaeffer; S. Schnetzer; S. Somalwar; V. Speziali; R. Stone; R. J. Tapper; R. Tesarek; W. Trischuk; R. Turchetta; G. B. Thomson; R. Wagner; P. Weilhammer; C. White; H. Ziock; M. Zoeller

1995-01-01

26

Modeling of diamond radiation detectors  

NASA Astrophysics Data System (ADS)

We have built up a computer simulation of the detection mechanism in the diamond radiation detectors. The diamond detectors can be fabricated from a chemical vapour deposition polycrystalline diamond film. In this case, the trapping-detrapping and recombination at the defects inside the grains and at the grain boundaries degrade the transport properties of the material and the charge induction processes. These effects may strongly influence the device's response. Previous simulations of this kind of phenomena in the diamond detectors have generally been restricted to the simple detector geometries and homogeneous distribution of the defects. In our model, the diamond film (diamond detector) is simulated by a grid. We apply a spatial and time discretization, regulated by the grid resolution, to the equations describing the charge transport and, by using the Shockley-Ramo theorem, we calculate the signal induced on the electrodes. In this way, we can simulate the effects of the nonhomogeneous distributions of the trapping, recombination, or scattering centers and can investigate the differences observed when different particles, energies, and electrode configurations are used. The simulation shows that the efficiency of the detector increases linearly with the average grain size, that the charge collection distance is small compared to the dimensions of a single grain, and that for small grains, the trapping at the intragrain defects is insignificant compared to the effect of the grain boundaries.

Milazzo, L.; Mainwood, A.

2004-11-01

27

Modeling of diamond radiation detectors  

SciTech Connect

We have built up a computer simulation of the detection mechanism in the diamond radiation detectors. The diamond detectors can be fabricated from a chemical vapour deposition polycrystalline diamond film. In this case, the trapping-detrapping and recombination at the defects inside the grains and at the grain boundaries degrade the transport properties of the material and the charge induction processes. These effects may strongly influence the device's response. Previous simulations of this kind of phenomena in the diamond detectors have generally been restricted to the simple detector geometries and homogeneous distribution of the defects. In our model, the diamond film (diamond detector) is simulated by a grid. We apply a spatial and time discretization, regulated by the grid resolution, to the equations describing the charge transport and, by using the Shockley-Ramo theorem, we calculate the signal induced on the electrodes. In this way, we can simulate the effects of the nonhomogeneous distributions of the trapping, recombination, or scattering centers and can investigate the differences observed when different particles, energies, and electrode configurations are used. The simulation shows that the efficiency of the detector increases linearly with the average grain size, that the charge collection distance is small compared to the dimensions of a single grain, and that for small grains, the trapping at the intragrain defects is insignificant compared to the effect of the grain boundaries.

Milazzo, L.; Mainwood, A. [Physics Department, King's College London, Strand, London WC2R 2LS (United Kingdom)

2004-11-15

28

Direct detector for terahertz radiation  

DOEpatents

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

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

2008-09-02

29

49 CFR 173.310 - Exceptions for radiation detectors.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Exceptions for radiation detectors. 173.310 Section 173.310 Transportation...Packaging § 173.310 Exceptions for radiation detectors. Radiation detectors, radiation sensors, electron tube devices,...

2010-10-01

30

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

31

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

32

Radiation experience with the CDF silicon detectors  

SciTech Connect

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

Husemann, Ulrich; /Rochester U.

2005-11-01

33

Active microphonic noise cancellation in radiation detectors  

NASA Astrophysics Data System (ADS)

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

Zimmermann, Sergio

2013-11-01

34

The pyroelectric detector of infrared radiation  

Microsoft Academic Search

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

H. P. Beerman

1969-01-01

35

Radiation hardness of the PIBETA detector components  

Microsoft Academic Search

We have examined long term changes in signal amplitude gain, energy resolution and detection efficiency for the active components of the PIBETA detector system. Beam defining plastic scintillation counters were operated in a ~1 MHz stopped $\\\\pi^+$ beam for a period of 297 days, accumulating radiation doses of up to 2 Mrad. Detectors in the charged particle tracking system--a pair

E. Frlez; T. A. Campbell; I. J. Carey; D. Pocanic

2002-01-01

36

Dielectron physics with ALICE Transition Radiation Detector  

Microsoft Academic Search

The Transition Radiation Detector (TRD) of ALICE will serve to identify and track electrons in the central region. In this contribution, after a brief introduction of TRD, we review the detector performance concerning electron\\/pion identification as well as J\\/? and ? detection.

Prashant Shukla

2006-01-01

37

Dose response of various radiation detectors to synchrotron radiation  

Microsoft Academic Search

Accurate dosimetry is particularly difficult for low- to medium-energy x-rays as various interaction processes with different dependences on material properties determine the dose distribution in tissue and radiation detectors. Monoenergetic x-rays from synchrotron radiation offer the unique opportunity to study the dose response variation with photon energy of radiation detectors without the compounding effect of the spectral distribution of x-rays

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

1998-01-01

38

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

39

Synchrotron light sources and radiation detector metrology  

NASA Astrophysics Data System (ADS)

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

Owens, Alan

2012-12-01

40

Metallisation of single crystal diamond radiation detectors  

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

41

Radiation-hardened optoelectronic components - Detectors  

NASA Astrophysics Data System (ADS)

Recent research in the area of radiation-hardened optical detectors are surveyed. Conventional silicon photodiode structures, special radiation-hardened silicon photodiodes, and special double heterojunction AlGaAs/GaAs photodiodes are studied in neutron, gamma, pulsed X-ray and charged particle environments. Results are studied of this work and other research in this area are presented. These studies have shown that detectors can be made to function acceptably after exposures to neutron fluences of 10 to the 15th n/sq cm, total dose gamma exposures of 10 to the 8th rad (Si), and flash X-ray environments of 10 to the 8th rad/sec (Si). Detector structures that can operate through these conditions, prerad and postrad operational characteristics, and experimental conditions that produced these results are described.

Wiczer, James J.

1986-01-01

42

Radiation detector with improved performance characteristics  

Microsoft Academic Search

A radiation detector of the gas-filled counter tube type which has a reduced count rate drift is described. An electrically conductive coating is applied to the interior insulating surfaces in proximity to the anode wire of a gas-filled counter tube structure having an axially disposed wire anode. The electrically conductive coating is maintained at the same electrical potential as the

Stokes

1979-01-01

43

Radiation hardness of the PIBETA detector components  

Microsoft Academic Search

We have examined long term changes in signal amplitude gain, energy res- olution and detection efficiency for the active components ofthe PIBETA de- tector system. Beam defining plastic scintillation counters were operated in a ?1MHz stopped ?+ beam for a period of 297 days, accumulating radiation doses of up to 2 ? 106 rad. Detectors in the charged particle tracking

E. Frleÿz; T. A. Campbell; I. J. Carey; D. Poÿcanic

44

Silicon detectors for synchrotron radiation digital mammography  

NASA Astrophysics Data System (ADS)

The knowledge of the dose and of the energy spectrum of the X-rays delivered to the patient during a radiological examination allows in principle the computation of the number of photons per unit surface useful for a good mammography. The film-screen assembly detectors used in the present standard practice require a number of photons per unit surface which, from a statistical point of view, would be unnecessarily high if single photon counting detectors with efficiency near to one were available. We discuss a possible solid state detector with these characteristics. Moreover, we propose the use of an X-ray monochromatic beam from a synchrotron radiation source in order to perform the examination at the energy where the signal to noise ratio has a maximum. Using the proposed detector in such a beam a substantial dose reduction can be foreseen.

Arfelli, F.; Barbiellini, G.; Cantatore, G.; Castelli, E.; Palma, L. Dalla; Michiel, M. Di; Longo, R.; Poropat, P.; Rosei, R.; Sessa, M.; Tromba, G.; Vacchi, A.

1995-02-01

45

High resolution amorphous silicon radiation detectors  

DOEpatents

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

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

1992-05-26

46

The Radiation Assessment Detector (RAD) Investigation  

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

47

Electromechanically cooled germanium radiation detector system  

NASA Astrophysics Data System (ADS)

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

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

1999-02-01

48

Dose response of various radiation detectors to synchrotron radiation  

NASA Astrophysics Data System (ADS)

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

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

1998-11-01

49

3-D GaAs radiation detectors  

NASA Astrophysics Data System (ADS)

A novel type of GaAs radiation detector featuring a 3-D array of electrodes that penetrate through the detector bulk is described. The development of the technology to fabricate such a detector is presented along with electrical and radiation source tests. Simulations of the electrical characteristics are given for detectors of various dimensions. Laser drilling, wet chemical etching and metal evaporation were used to create a cell array of nine electrodes, each with a diameter of 60?m and a pitch of 210?m. Electrical measurements showed /I-/V characteristics with low leakage currents and high breakdown voltages. The forward and reverse /I-/V measurements showed asymmetrical characteristics, which are not seen in planar diodes. Spectra were obtained using alpha particle illumination. A charge collection efficiency of 50% and a S/N ratio of 3:1 were obtained. Simulations using the MEDICI software package were performed on cells with various dimensions and were comparable with experimental results. Simulations of a nine-electrode cell with 10?m electrodes with a 25?m pitch were also performed. The /I-/V characteristics again showed a high breakdown voltage with a low leakage current but also showed a full depletion voltage of just 8V.

Meikle, A. R.; Bates, R. L.; Ledingham, K.; Marsh, J. H.; Mathieson, K.; O'Shea, V.; Smith, K. M.

2002-01-01

50

Window for radiation detectors and the like  

DOEpatents

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

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

1975-10-28

51

Radiation hardness of the PIBETA detector components  

Microsoft Academic Search

We have examined long term changes in signal amplitude gain, energy\\u000aresolution and detection efficiency for the active components of the PIBETA\\u000adetector system. Beam defining plastic scintillation counters were operated in\\u000aa ~1 MHz stopped $\\\\pi^+$ beam for a period of 297 days, accumulating radiation\\u000adoses of up to 2 Mrad. Detectors in the charged particle tracking system--a\\u000apair

E. Frleÿz; T. A. Campbell; I. J. Carey; D. Poÿcanic

2002-01-01

52

Experiences with radiation portal detectors for international rail transport  

Microsoft Academic Search

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)

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

2006-01-01

53

VERDI: A versatile readout ASIC for radiation detectors  

Microsoft Academic Search

In this work we present the circuit VERDI (VErsatile Readout for Detector Integration), an integrated circuit developed for the readout of different families of radiation detectors, from nitrogen-cooled Ge and Si(Li) detectors, to silicon drift detectors (SDDs), scintillation detectors, photomultipliers tubes and others. The circuit may represent a suitable solution when a compact integration between a multi-element detector and the

A. Celani; L. Bombelli; C. Fiorini; T. Frizzi; R. Nava; J. Pavlick; M. Kastner; M. Morichi; B. Roberson; B. Zakrzewski; O. Evrard; C. Cherukuri; S. Assouak

2010-01-01

54

CVD diamond detectors for radiation pulse characterisation  

NASA Astrophysics Data System (ADS)

Polycrystalline diamond films deposited by microwave plasma-enhanced chemical vapour deposition (MPCVD) have been used for the fabrication of resistive photoconductors. Such detectors can be used to measure the intensity and the temporal shape of pulsed radiation such as IR, visible, UV and X-rays. The photodetector response times were characterised under fast Nd:Yag laser pulses (? = 266 nm, ?L = 30 ps at FWHM). The detector sensitivities were measured under both pulsed UV laser and steady-state X-ray excitations (40 keV). The detector response time strongly depends on the CVD diamond film structural and physical properties, i.e., the film growth conditions. They exhibit a response signal presenting full widths at half maximum down to about 100 ps and decay times down to about 130 ps. The diamond detector responses are compared to the responses measured on typical ultrafast photoconductors made from gallium arsenide pre-irradiated at 3 × 1015 neutrons/cm2 as well as from natural type IIa bulk diamond.

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

55

Nuclear Radiation Silicon Detectors with Silicide-Silicon Junctions.  

National Technical Information Service (NTIS)

It is shown that in order to increase the reliability of nuclear radiation detectors silicide-silicon junctions could be used. The thickness of input windows, leakage current and energy resolution of detectors with palladium silicide-silicon junction are ...

I. Brylowska K. Paprocki M. Walerian Kim Chan Khvan Nguen Thanh Hanh

1986-01-01

56

Radiation damage measurements in room temperature semiconductor radiation detectors  

Microsoft Academic Search

The literature of radiation damage measurements on cadmium zinc telluride (CZT), cadmium telluride (CT), and mercuric iodide (HgIâ) is reviewed and in the case of CZT supplemented by new alpha particle data. CZT strip detectors exposed to intermediate energy (1.3 MeV) proton fluences exhibit increased interstrip leakage after 10¹° p\\/cm² and significant bulk leakage after 10¹² p\\/cm². CZT exposed to

Larry A. Franks; R. W. Olsen; R. B. James; B. A. Brunett; D. S. Walsh; B. L. Doyle; G. Vizkelethy; J. I. Trombka

1998-01-01

57

Radiation damage measurements in room-temperature semiconductor radiation detectors  

Microsoft Academic Search

The literature of radiation damage measurements on cadmium zinc telluride (CZT), cadmium telluride (CT), and mercuric iodide (HgI2) is reviewed and in the case of CZT supplemented by new alpha particle data. CZT strip detectors exposed to intermediate energy (1.3MeV) proton fluences exhibit increased interstrip leakage after 1010 p\\/cm2 and significant bulk leakage after 1012 p\\/cm2. CZT exposed to 200MeV

L. A. Franks; B. A. Brunett; R. W. Olsen; D. S. Walsh; G. Vizkelethy; J. I. Trombka; B. L. Doyle; R. B. James

1999-01-01

58

RMD-10T radiation microtronic flaw detector  

SciTech Connect

The development of nuclear power engineering and other branches of industry using welded components with a weld thickness of 100-300 mm and greater requires the use of electron accelerators for flaw inspection. One of the most suitable types of accelerator is the microtron. The design of RMD-10T radiation microtronic flaw detector is examined; the technical characteristics of its individual sections and the results of examination during starting up of equipment are presented and the radiographic characteristics obtained in inspection of steel components and specimens are given.

Zakirov, B.S.; Kapitsa, S.P.; Leonov, B.I.; Luk'yanenko, E.A.; Melekhin, V.N.; Tokarev, Yu, E.

1987-09-01

59

Radiation detector with remote temperature reference  

SciTech Connect

A radiation detector is described comprising: a thermopile having a hot junction and a cold junction, the thermopile sensing radiation emitted from a target and providing an output signal indicative of a temperature of the target; and a thermocouple having a hot junction and a cold junction, one of said thermocouple junctions being thermally remote from the hot and cold junctions of the thermopile, the thermocouple being electrically connected in series with the thermopile in a passive circuit and providing an output signal which combines with the output signal of the thermopile to produce a total output signal, a change in the thermocouple output signal with a local temperature being inversely related to a change in the thermopile output signal with said local temperature.

Pompei, F.; Ternullo, J.

1993-07-20

60

Radiation detector having a multiplicity of individual detecting elements  

DOEpatents

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

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

1985-01-01

61

Portable radiation detector and mapping system  

SciTech Connect

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

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

1995-09-01

62

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

63

SEMICONDUCTOR DETECTORS IN RADIATION MEDICINE: RADIOTHERAPY AND RELATED APPLICATIONS  

Microsoft Academic Search

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

ANATOLY B. ROSENFELD; Wollongong NSW

64

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

65

Radiation Effect On Gas Electron Multiplier Detector Performance  

NASA Astrophysics Data System (ADS)

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

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

2011-06-01

66

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

67

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

Microsoft Academic Search

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

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

2009-01-01

68

Radiation damage measurements in room temperature semiconductor radiation detectors  

SciTech Connect

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

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

1998-12-01

69

Personal Radiation Detector Field Test and Evaluation Campaign.  

National Technical Information Service (NTIS)

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. ...

C. A. Hodge D. Yuan M. A. Krstich R. P. Keegan

2007-01-01

70

Radiation tests with foxfet biased microstrip detectors  

NASA Astrophysics Data System (ADS)

The silicon detectors at the future Large Hadron Collider (LHC) at CERN have to survive large particle fluxes up to a few 1014 particles per cm2. These high fluxes cause dramatic changes in the behaviour of the silicon detectors, like inversion of n-type silicon to p-type silicon. Here, we report on the high-voltage behaviour of silicon mictrostrip detectors up to doses of about 1014 particles/cm2, and the changes in the depletion voltage and inter-strip capacitance. The CMS baseline choice for the biasing element of the AC-coupled microstrip detectors is a polysilicon resistor. The silicon detectors, tested here, are Foxfet biased. We measured the changes in the Foxfet characteristics. Such detectors have been reported to show, after irradiation, a noise which is higher than expected. Using a fast amplifier (PREMUX chip), we also measure a higher noise.

Hammarstrom, R.; Kellogg, R.; Mannelli, M.; Piperov, S.; Runolfsson, O.; Schmitt, B.

1998-11-01

71

Radiation effects on II–VI compound-based detectors  

Microsoft Academic Search

The performance of room temperature CdTe and CdZnTe detectors exposed to a radiation source can be strongly altered by the interaction of the ionizing particles and the material. Up to now, few experimental data are available on the response of II–VI compound detectors to different types of radiation sources. We have carried out a thorough investigation on the effects of

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

2002-01-01

72

Performance of the transition radiation detector of the MACRO experiment  

Microsoft Academic Search

A transition radiation detector (TRD) consisting of three identical modules each of 12m2 area, has been developed and installed on the MACRO detector at the Gran Sasso National Laboratory. The modular structure, based on single proportional tubes and polyethylene foam radiators, allows to cover a large area. The TRD measures the residual energies (up to 1TeV) of penetrating muons at

M. N. Mazziotta; R Antolini; G Auriemma; R Baker; A Baldini; G C Barbarino; B C Barish; G Battistoni; R Bellotti; C Bemporad; P Bernardini; H Bilokon; V Bisi; C Bloise; T Bosio; C Bower; S Bussino; F Cafagna; M Calicchio; D Campana; M Carboni; M G Castellano; S Cecchini; F Cei; V Chiarella; A Corona; S Coutu; L De Benedictis; G De Cataldo; H Dekhissi; C De Marzo; I De Mitri; M De Vincenzi; A Di Credico; O Erriquez; R Fantini; C Favuzzi; C Forti; P Fusco; G Giacomelli; G Giannini; N Giglietto; M Goretti; M Grassi; P Green; A Grillo; F Guarino; P Guarnaccia; C Gustavino; A Habig; K Hanson; A Hawthorne; R Heinz; J T Hong; Enzo Iarocci; E Katsavounidis; E T Kearns; S Kyriazopoulou; E Lamanna; D S Levin; P Lipari; G Liu; R Liu; N P Longley; M J Longo; G Ludlam; F Maaroufi; G Mancarella; G Mandrioli; A Margiotta-Neri; A Marini; D Martello; A Marzari-Chiesa; D G Michael; S P Mikheyev; L Miller; P Monacelli; T Montaruli; M Monteno; S L Mufson; J Musser; D Nicoló; R Nolty; C Okada; C Orth; G Osteria; O Palamara; S Parlati; V Patera; L Patrizii; R Pazzi; C W Peck; S Petrera; N D Pignatano; P Pistilli; V Popa; A Rainó; J Reynoldson; F Ronga; U Rubizzo; A Sanzgiri; F Sartogo; C Satriano; L Satta; E Scapparone; K Scholberg; A Sciubba; P Serra-Lugaresi; M Severi; M Sioli; M Sitta; P F Spada; P Spinelli; M Spinetti; M Spurio; R Steinberg; J L Stone; Lawrence R Sulak; A Surdo; G Tarlé; V Togo; V Valente; E Vilela; C W Walter; R Webb

1997-01-01

73

Design and construction of the prototype synchrotron radiation detector  

Microsoft Academic Search

The Prototype Synchrotron Radiation Detector (PSRD) is a small-scale experiment designed to measure the rate of low-energy charged particles and photons in near the Earth's orbit. It is a precursor to the Synchrotron Radiation Detector (SRD), a proposed addition to the upgraded version of the Alpha Magnetic Spectrometer (AMS-02). The SRD will use the Earth's magnetic field to identify the

H. Anderhub; J. R. Bates; D. Bätzner; S. Baumgartner; A. Biland; C. Camps; M. Capell; V. Commichau; L. Djambazov; Y.-J. Fanchiang; G. Flügge; M. Fritschi; O. Grimm; K. Hangarter; H. Hofer; U. Horisberger; R. Kan; W. Kästli; G. P. Kenney; G. N. Kim; K. S. Kim; V. Koutsenko; M. Kräber; J. Kuipers; A. Lebedev; M. W. Lee; S.-C. Lee; R. Lewis; W. Lustermann; F. Pauss; T. Rauber; D. Ren; Z. L. Ren; U. Röser; D. Son; Samuel C. C. Ting; A. N. Tiwari; G. M. Viertel; H. von Gunten; S. Waldmeier Wicki; T.-S. Wang; J. Yang; B. Zimmermann

2002-01-01

74

Characterisation of bubble detectors for aircrew and space radiation exposure.  

PubMed

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

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

2006-01-01

75

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

76

A hybrid radiation detector for simultaneous spatial and temporal dosimetry.  

PubMed

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

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

2011-06-16

77

VeriTainer radiation detector for intermodal shipping containers  

Microsoft Academic Search

The VeriSpreaderTM 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

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

2007-01-01

78

Radiation effects on optoelectronic analog link for particle detectors  

SciTech Connect

The successful operation of an optoelectronic analog link for transfer of particle detector signals in high radiation area requires a detailed radiation damage study. We present at this conference the study of Ti: LiNbO[sub 3] optical modulators with gamma-rays and neutrons.

Tsang, T.

1993-05-01

79

Tracking and Radiation Field Measurement with Pixel Detectors  

NASA Astrophysics Data System (ADS)

Continuous advances in the miniaturization of semiconductor technology allow nowadays fabrication of devices with performance exceeding the photographic techniques (nuclear emulsion). Single particle counting pixellated detectors open up a whole new field of possibilities in real-time detection and visualization of radiation and understanding its interaction in matter. Pixel detectors allows to visualize directly the ionization paths of different types of radiation, with additional energy and time information, even at very low fluxes which can be used for reconstruction of the incident radiation field.

Vykydal, Zdenek; Granja, Carlos; Jakubek, Jan; Platkevic, Michal; Pospisil, Stanislav

2010-01-01

80

A radiation monitor for the ZEUS detector at HERA  

Microsoft Academic Search

A radiation monitoring and automatic beam-dump system has been installed in the interaction region of the ZEUS experiment during the last upgrade of the electron\\/positron-proton collider HERA. It is used to prevent the ZEUS Silicon Microvertex Detector (MVD) from beam-background induced radiation damage during HERA operation. The dose rate measurement is based on the readout of radiation induced signal currents

Ingo Bloch; Enrico Borsato; Roberto Carlin; Flavio Dal Corso; Dominik Dannheim; Benjamin Kahle; Katarzyna Klimek; U. Kotz; G. Kramberger; A. Longhin; I. Melzer-Pellmann; M. Milite

2003-01-01

81

Radiation-hard semiconductor detectors for SuperLHC  

NASA Astrophysics Data System (ADS)

An option of increasing the luminosity of the Large Hadron Collider (LHC) at CERN to 1035 cm-2 s-1 has been envisaged to extend the physics reach of the machine. An efficient tracking down to a few centimetres from the interaction point will be required to exploit the physics potential of the upgraded LHC. As a consequence, the semiconductor detectors close to the interaction region will receive severe doses of fast hadron irradiation and the inner tracker detectors will need to survive fast hadron fluences of up to above 1016 cm-2. The CERN-RD50 project “Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders” has been established in 2002 to explore detector materials and technologies that will allow to operate devices up to, or beyond, this limit. The strategies followed by RD50 to enhance the radiation tolerance include the development of new or defect engineered detector materials (SiC, GaN, Czochralski and epitaxial silicon, oxygen enriched Float Zone silicon), the improvement of present detector designs and the understanding of the microscopic defects causing the degradation of the irradiated detectors. The latest advancements within the RD50 collaboration on radiation hard semiconductor detectors will be reviewed and discussed in this work.

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

2005-04-01

82

UTILIZATION OF PHOSWICH DETECTORS FOR SIMULTANEOUS, MULTIPLE RADIATION DETECTION  

SciTech Connect

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

William H. Miller; Manuel Diaz de Leon

2003-04-15

83

Fabrication of mercuric iodide radiation detectors  

NASA Astrophysics Data System (ADS)

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

van den Berg, L.; Vigil, R. D.

2001-02-01

84

A fiber detector radiation hardness test  

NASA Astrophysics Data System (ADS)

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

Bähr, J.; Nahnhauer, R.; Nerreter, S.; Shanidze, R.

2000-07-01

85

Recent advances in compound semiconductor radiation detectors  

NASA Astrophysics Data System (ADS)

Recent developments in compound semiconductor detectors are reviewed, highlighting the latest spectroscopic performance from devices fabricated from a range of wide bandgap materials. Cadmium zinc telluride and cadmium telluride continue to dominate the field, with a range of prototype imaging detectors under development, principally for nuclear medicine and X-ray astronomy applications. Improvements in material quality and supply plus metal-semiconductor contact technologies are discussed, as is the continued development of single polarity charge sensing electrode structures. Other material systems are also reviewed, covering the latest results from intermediate-Z materials such as gallium arsenide and indium phosphide, and high-Z materials including mercuric iodide and thallium bromide. The technological challenges of these materials are summarised and the prospects for future imaging array detectors highlighted.

Sellin, Paul J.

2003-11-01

86

Sensing of pulsed radiation with Pyroelectric Detectors  

Microsoft Academic Search

In existing literature, the response of a Pyroelectric Detector (PED) has been modeled almost exclusively with slow varying excitation signals having the shape of either a square or sinusoidal wave. Their naturally slow thermal response (~1 second) is not favourable in view of their use in a variety of faster existing or emerging applications. Even so, PEDs are still good

Spyros Efthymiou; Krikor B Ozanyan

2010-01-01

87

Surface Wave Chemical Detector Using Optical Radiation.  

National Technical Information Service (NTIS)

A surface wave chemical detector comprising at least one surface wave substrate, each of said substrates having a surface wave and at least one measurable surface wave parameter; means for exposing said surface wave substrate to an unknown sample of at le...

R. J. Warmack T. G. Thundat

2005-01-01

88

Silicon detectors for synchrotron radiation digital mammography  

Microsoft Academic Search

The knowledge of the dose and of the energy spectrum of the X-rays delivered to the patient during a radiological examination allows in principle the computation of the number of photons per unit surface useful for a good mammography. The film-screen assembly detectors used in the present standard practice require a number of photons per unit surface which, from a

F. Arfelli; G. Barbiellini; G. Cantatore; E. Castelli; L. Dalla Palma; M. Di Michiel; R. Longo; P. Poropat; R. Rosei; M. Sessa; G. Tromba; A. Vacchi

1995-01-01

89

Silicon p-n Junction Radiation Detectors  

Microsoft Academic Search

Silicon p-n junction particle detectors have been fabricated by diffusing phosphorus to various depths between 0.1 and 2.0 ¿ into high resistivity p-type silicon. Various base material resistivities have been employed, ranging from 100 ¿ cms to 13,000 ¿ cms. Diffusions have been carried out both by the \\

G. L. Miller; W. L. Brown; P. F. Donovan; I. M. Mackintosh

1960-01-01

90

Pocket dual Neutron\\/Gamma radiation detector  

Microsoft Academic Search

A pocket radiation detection system has been developed at the INEEL for homeland security applications. It can detect both neutrons and gamma rays instantaneously. This sensor has been designed with an emphasis on compactness' recognizing the widespread need for a radiation detection instrument that could provide both neutron and gamma ray detection in a single, portable unit. It is very

Rahmat Aryaeinejad; David F. Spencer

2003-01-01

91

Pocket dual neutron\\/gamma radiation detector  

Microsoft Academic Search

A pocket radiation detection system has been developed at the Idaho National Engineering and Environmental Laboratory for homeland security applications. It can detect both neutrons and gamma rays instantaneously. This sensor has been designed with an emphasis on compactness, recognizing the widespread need for a radiation detection instrument that could provide both neutron and gamma-ray detection in a single, portable

Rahmat Aryaeinejad; David F. Spencer

2004-01-01

92

Operation of silicon microstrip detectors in a high radiation environment  

SciTech Connect

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

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

1990-01-01

93

Novel detector for portal imaging in radiation therapy  

Microsoft Academic Search

We are developing a novel concept for portal imaging that would allow for on-line control and verification of the radiation treatment of cancer patients both at diagnostic and therapeutic energies. This device will consist of two consecutive detectors confided in one gas chamber: a KeV- photon detector, which can visualize the internal soft tissue of the patient, and an MeV-photon

Janina Ostling; M. Wallmark; Anders Brahme; Mats Danielsson; Christian Iacobaeus; P. Fonte; Vladimir N. Peskov

2000-01-01

94

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

Microsoft Academic Search

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

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

2004-01-01

95

R&D for Better Nuclear Security: Radiation Detector Materials  

SciTech Connect

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

Kammeraad, J E

2009-04-02

96

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

97

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

98

Semiconductor radiation detector with internal gain  

DOEpatents

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

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

2003-04-01

99

Synchrotron radiation applications of charge coupled device detectors (invited)  

SciTech Connect

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

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

1992-01-01

100

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

101

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

102

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

103

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

104

Online Integrating Radiation Monitoring System for the ATLAS Detector at the Large Hadron Collider  

Microsoft Academic Search

Detectors and electronics inside the ATLAS detector at the large hadron collider will be exposed to high fluxes of photons, charged particles, and neutrons. Damage caused by radiation will influence the performance of the detector. It will therefore be important to continuously monitor the radiation dose to follow the level of detector degradation. It will also be important to have

I.. Mandic; V.. Cindro; A.. Gorisek; G.. Kramberger; M.. Mikuz

2007-01-01

105

Detector for electromagnetic radiation and a method of detecting electromagnetic radiation  

US Patent & Trademark Office Database

A detector for detecting electromagnetic radiation, especially for electromagnetic radiation in the GHz or THz range. The detector comprises a semiconductor structure having a 2D charge carrier layer or a quasi 2D charge carrier layer with an edge, at least first and second contacts to said charge carrier layer, said contacts being provided at said edge and being spaced apart by a distance, and a device for measuring at least one of the photocurrent between said first and second contacts, the photovoltage between said first and second contacts and the resistance between said first and second contacts. A device is provided for applying a magnetic field to said detector with a field component perpendicular to said charge carrier layer. An output signal of said measuring device provides information about at least one of the presence of electromagnetic radiation, the intensity of the incident electromagnetic radiation and the frequency of the incident electromagnetic radiation.

2006-01-17

106

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

107

Test of radiation detectors used in homeland security applications.  

PubMed

This work was performed as part of the National Institute of Standards and Technology (NIST) program to support the development of the new American National Standards Institute (ANSI) standards N42.32-2003 and N42.33-2003 for hand-held detectors, and personal electronic dosimeters, as well as to support the Office of Law Enforcement Standards (OLES) and the Department of Homeland Security (DHS) in testing these types of detectors for their use by first responders. These instruments are required to operate over a photon energy range of 60 keV to 1.33 MeV and over a wide range of air-kerma rates. The performance and response of various radiation detectors, purchased by the NIST, was recorded when placed in 60Co, 137Cs, and x-ray beams at different air-kerma rates. The measurements described in this report were performed at the NIST x-ray and gamma-ray radiation calibration facilities. The instruments' response (exposure or dose rate readings) shows strong energy dependence but almost no dependence to different air-kerma rates. The data here reported provide a benchmark in support of current protocols that are being developed for radiation detection instrumentation used in homeland security applications. A future plan is to test these devices, plus other commercially available detectors, against ANSI standards N42.32-2003 and N42.33-2003. PMID:15824588

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

2005-05-01

108

Advanced technology lunar telescopes III. Radiation resistant detectors  

SciTech Connect

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

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

1993-01-01

109

Calculations for a disk source and a general detector using a radiation vector potential  

Microsoft Academic Search

A closed form expression for a radiation vector potential is derived for a generalized disk radiation source. By applying Stokes's theorem the surface integral for the radiation flux into a general detector is converted into a much simpler line integral of the vector potential around the edge of the detector. This line integral can be easily evaluated for general detector

John T. Conway

2008-01-01

110

Charge transport properties of CdMnTe radiation detectors  

SciTech Connect

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

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

2012-04-11

111

Super-thin single crystal diamond membrane radiation detectors  

NASA Astrophysics Data System (ADS)

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

Pomorski, Michal; Caylar, Benoit; Bergonzo, Philippe

2013-09-01

112

Charge transport properties of CdMnTe radiation detectors  

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

113

Experimental Analysis of Noise in CdTe Radiation Detectors  

NASA Astrophysics Data System (ADS)

Noise characteristics of CdTe gamma and X-ray detectors have been carried out. Samples were prepared at Physical Institute of Charles University in Prague by traveling heater method (THM). Measurements of high-ohmic detectors with two golden contacts and low-ohmic detectors with four contacts were carried out. Two voltage contacts were used to distinguish between metal-semiconductor junction area with depleted region and homogeneous part of the sample. The resistance of high-ohmic samples is in the range from hundreds of M? up to several G?. The noise characteristics of the samples were measured in dark and with the illumination in the range of radiation from ultraviolet to infrared.

Andreev, A.; Grmela, L.; Raska, M.; Sikula, J.; Moravec, P.

2009-04-01

114

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

115

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

116

Modelling radiation loads to detectors in a SNAP mission.  

PubMed

In order to investigate the degradation of optical detectors of the Supernova Acceleration Project (SNAP) space mission because of irradiation, a three-dimensional model of the satellite has been developed. A realistic radiation environment at the satellite orbit, including both galactic cosmic rays and cosmic ray trapped in radiation belts, has been taken into account. The modelling has been performed with the MARS14 Monte Carlo code. In a current design, the main contribution to dose accumulated in the photo-detectors is shown to be due to trapped protons. The contribution of primary alpha particles is estimated. Predicted performance degradation for the photodetector for a four-year space mission is 40% and this can be reduced further by means of shielding optimisation. PMID:16604632

Mokhov, N V; Rakhno, I L; Striganov, S I; Peterson, T J

2005-01-01

117

New designs of CMS silicon pixel detectors for radiation hardness  

NASA Astrophysics Data System (ADS)

New designs of silicon pixel detectors with n+/n/p+ and double-sided multiguard ring structures have been developed for more radiation-tolerant CMS forward pixel sensors. In a later design modification, guard rings on the n+ side are replaced with a single wide (640?m) n+ implant, and the entire n+ side and the edge region of the p+ side are grounded. All designs were fabricated from both normal and oxygen-enriched silicon wafers, and radiation hardness effects for neutron (1MeV equivalent) and proton (24GeV) irradiation of these detectors were compared. Other electrical characteristics such as leakage current, potential distribution over guard rings and full depletion voltage were tested, using standard techniques of I-V, V-V, C-V and TCT before and after irradiation.

Chien, C. Y.; Cho, H. S.; Huang, W.; Li, Z.; Liang, G. W.; Xie, X. B.

2000-12-01

118

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

119

Fabrication techniques for reverse electrode coaxial germanium nuclear radiation detectors  

SciTech Connect

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

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

1980-11-01

120

A hybrid radiation detector for simultaneous spatial and temporal dosimetry  

Microsoft Academic Search

In this feasibility study an organic plastic scintillator is calibrated against ionisation chamber measurements and then embedded\\u000a in a polymer gel dosimeter to obtain a quasi-4D radiation detector. This hybrid dosimeter was irradiated with megavoltage\\u000a x-rays from a linear accelerator, with temporal measurements of the dose rate being acquired by the scintillator and spatial\\u000a measurements acquired with the gel dosimeter.

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

121

VeriTainer radiation detector for intermodal shipping containers  

NASA Astrophysics Data System (ADS)

The VeriSpreaderTM 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

Simple classical model for Fano statistics in radiation detectors  

NASA Astrophysics Data System (ADS)

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

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

2008-02-01

123

Radiation damage studies of cerium-doped radiation-resistant lead glass detectors  

Microsoft Academic Search

Optical absorption measurements have been made on unirradiated and irradiated samples of cerium oxide doped lead silicate particle detector glasses. The addition of CeO2 introduces one prominent and one weak absorption band near the ultraviolet transmission limit. However the CeO2 greatly reduces the rate of formation of the radiation induced absorption. Detector size blocks of lead glass with 0.0, 0.25,

M. R. Adams; R. Engelmann; P. D. Grannis; J. Horstkotte; L. Godfrey; S. L. Linn; M. D. Marx; J. Timms; P. M. Tuts; J. Willins; L. Ahrens; S. Aronson; P. W. Levy; P. Yamin; P. Franzini; S. Youssef; D. Cutts; J. Callas

1985-01-01

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

Preliminary results from the prototype synchrotron radiation detector on space shuttle mission STS108  

Microsoft Academic Search

A Synchrotron Radiation Detector measures synchrotron radiation emitted by high energetic particles in the earth magnetic field. This allows to identify cosmic ray electrons and positrons with energies in the TeV region. One possibility for such a detector outside the atmosphere uses YAP crystals to measure synchrotron photons with energies in the keV range. As such a detector can not

H. Anderhub; J. R. Bates; D. Bätzner; S. Baumgartner; A. Biland; C. Camps; M. Capell; V. Commichau; L. Djambazov; Y.-J. Fanchiang; G. Flügge; M. Fritschi; O. Grimm; K. Hangarter; H. Hofer; U. Horisberger; R. Kan; W. Kästli; G. P. Kenney; G. N. Kim; K. S. Kim; V. Koutsenko; M. Kräber; J. Kuipers; A. Lebedev; M. W. Lee; S.-C. Lee; R. Lewis; W. Lustermann; F. Pauss; T. Rauber; D. Ren; Z. L. Ren; U. Röser; D. Son; Samuel C. C. Ting; A. N. Tiwari; G. M. Viertel; H. von Gunten; S. Waldmeier Wicki; T.-S. Wang; J. Yang; B. Zimmermann

2002-01-01

126

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

127

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

128

Radiation detector resolution over a continuous energy range  

SciTech Connect

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

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

2007-08-27

129

Phonon-mediated detectors of radiation: state of the art  

NASA Astrophysics Data System (ADS)

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

Giuliani, Andrea

2001-12-01

130

PERDaix -Proton Electron Radiation Detector Aix-la-Chapelle  

NASA Astrophysics Data System (ADS)

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

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

131

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

132

Two-dimensional position sensitive transition radiation detector  

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

133

The charged particle response of silicon carbide semiconductor radiation detectors  

NASA Astrophysics Data System (ADS)

Silicon carbide (SiC) radiation detectors are being developed for high-temperature applications in harsh radiation environments. The wide band gap of SiC (3.25eV) compared to conventional semiconductors such as silicon (1.1eV) and the relatively high-radiation resistance of SiC make it a semiconductor, that is highly suited for such applications. In this paper, we report on charged particle response measurements with larger-sized diodes. The charged-particle response characteristics of these diodes were tested with 238Pu, 242Pu and 148Gd alpha-particle sources in air. Energies deposited by alpha particles from these sources were calculated using the SRIM range-energy code. The peak shapes are nearly Gaussian, with a full-width at half-maximum for 148Gd of 89.5keV corresponding to 1562keV deposited in the detector active volume. This measured resolution is greater than, but still comparable to, the resolution obtained with silicon alpha spectrometers. Range straggling for the energy fraction deposited in the 10-?m thick active layers contributes significantly to our observed energy resolution. Design parameters for an optimum SiC alpha spectrometer are discussed.

Ruddy, Frank H.; Dulloo, Abdul R.; Seidel, John G.; Palmour, John W.; Singh, Ranbir

2003-06-01

134

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

Microsoft Academic Search

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

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

2010-01-01

135

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

National Technical Information Service (NTIS)

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

F. Bradna V. Bradnova F. Yukl

1983-01-01

136

Nuclear Microprobe Studies of the Electronic Transport Properties of Cadmium Zinc Telluride (CZT) Radiation Detectors.  

National Technical Information Service (NTIS)

Beam Induced Charge Collection (IBICC) is a proven albeit relatively new method to measure the electronic transport properties of room temperature radiation detectors. Using an ion microbeam the charge collection efficiency of CZT detectors can be mapped ...

G. Vizkelethy B. L. Doyle D. S. Walsh R. B. James

2000-01-01

137

Measurement of the radiation field surrounding the Collider Detector at Fermilab  

SciTech Connect

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

K. Kordas et al.

2004-01-28

138

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

NASA Astrophysics Data System (ADS)

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

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

2007-08-01

139

Radiation hardness of silicon detectors for future colliders  

NASA Astrophysics Data System (ADS)

The radiation hardness of silicon pad detectors, especially developed for the PLUG-calorimeter of the H1 experiment at HERA was investigated with respect to neutron and electron irradiation. Be(d,n)-neutrons with an average energy of 6.2 MeV up to a fluence of 1015 n/cm2 and 1.8 MeV electrons up to a dose of 1 MGy (1016 e/cm2) were used. Degradation effects of the diode properties regarding the reverse current, depletion voltage and charge collection efficiency are studied at room temperature and with no bias applied during irradiation. Special emphasis is put on the separation of the respective damage generation and its subsequent self annealing. The observed effects are discussed with respect to radiation levels to be envisioned for experiments with future colliding beam machines.

Fretwurst, E.; Claussen, N.; Croitoru, N.; Lindström, G.; Papendick, B.; Pein, U.; Schatz, H.; Schulz, T.; Wunstorf, R.

1993-03-01

140

Ambient temperature cadmium zinc telluride radiation detector and amplifier circuit  

DOEpatents

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

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

1998-05-29

141

Experiences in flip chip production of radiation detectors  

NASA Astrophysics Data System (ADS)

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

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

2006-09-01

142

Transition radiation detectors: state of art and new developments  

NASA Astrophysics Data System (ADS)

Transition radiation (TR) is emitted whenever a fast particle (? > 1000) crosses the boundaries of a periodic structure. Since the prediction of this effect, many studies and tests have been accomplished to understand both the features of this radiation and the eventual practical applications. Nowadays. the main application of TR is particle identification in accelerator physics and astrophysics. Particle identification is one of the most challenging aspect of the experiments performed in these fields. In fact the experimental problems arisen in the recent accelerator physics pose stringent constraints on the detectors due to the high rates, severe background conditions, event final state complexity. On the other hand, the cosmic ray physics requires in some cases simple but refined and reliable devices to be used in outer space or otherwise huge and stable apparata for surface and underground laboratories. After a brief presentation of the TR phenomenon produced by ultrarelativistic particles and relative detectors, the state of the art of this particle identification technique relative to the more recent TRDs will be discussed.

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

2005-08-01

143

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

SciTech Connect

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; Uesugi, Kentaro; Inoue, Katsuaki [SPring-8/JASRI, Mikazuki, Sayo, Hyogo, 679-5198 (Japan); Yamamoto, Masaki [SPring-8/RIKEN, Mikazuki, Sayo, Hyogo, 679-5198 (Japan)

2004-05-12

144

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

SciTech Connect

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

Knoll, G.F.

1995-11-01

145

Use of radiation detectors in remote monitoring for containment and surveillance  

SciTech Connect

Radiation detectors have been included in several remote monitoring field trial systems to date. The present study considers detectors at Embalse, Argentina, and Oarai, Japan. At Embalse four gamma detectors have been operating in the instrumentation tubes of spent fuel storage silos for up to three years. Except for minor fluctuations, three of the detectors have operated normally. One of the detectors appears never to have operated correctly. At Oarai two gamma detectors have been monitoring a spent-fuel transfer hatch for over 18 months. These detectors have operated normally throughout the period, although one shows occasional noise spikes.

Dupree, S.A.; Ross, M. [Sandia National Labs., Albuquerque, NM (United States); Bonino, A. [Nuclear Regulatory Authority of Argentina, Buenos Aires (Argentina); Lucero, R.; Hasimoto, Yu [PNC Oarai Engineering Center, Ibaraki (Japan)

1998-07-01

146

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

147

Ion Microbeam Studies of Cadmium Zinc Telluride Radiation Detectors by IBICC  

Microsoft Academic Search

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

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

1998-01-01

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

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

150

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

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

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

153

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

DOEpatents

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

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

1996-10-22

154

Radiative processes for Rindler and accelerating observers and the stress-tensor detector  

Microsoft Academic Search

We consider a monopole detector interacting with a massive scalar field. The radiative processes are discussed from the accelerated frame point of view. After this, we obtain the Minkowski vacuum stress tensor measured by the accelerated observer using a non-gravitational stress tensor detector as discussed by Ford and Roman (PRD 48, 776 (1993)). Finally, we analyse radiative processes of the

R. De Paola; N. F. Svaiter

1996-01-01

155

Influence of intensive ? and electron radiation on tracks formation in the PM355 detectors  

Microsoft Academic Search

Solid-state nuclear track detectors have found wide use in various domains of science and technology, e.g. in plasma experiments. The track detectors used in the fusion-oriented experiments encounter “harsh” conditions (intense X-ray and neutron radiation, heat impact, shock waves and plasma fluxes). Therefore, such detectors should be tested under similar conditions. This paper concerns influence of electron and ? radiation

A. Szyd?owski; A. Banaszak; I. Fija?; M. Jaskó?a; A. Korman; M. Sadowski; Z. Zimek

2003-01-01

156

Development of radiation hard edgeless detectors with current terminating structure on p-type silicon  

NASA Astrophysics Data System (ADS)

The development of edgeless Si detectors was stimulated by the tasks of the total pp cross-section study in the TOTEM experiment at the Large Hadron Collider at CERN. For this, the dead region at the detector diced side should be reduced below 50 ?m. This requirement is successfully realized in edgeless Si detectors with current terminating structure (CTS), which are now operating at LHC. The development of the experiment and future LHC upgrade need the elaboration of radiation hard version of edgeless Si detectors. The current investigation represents an extension in understanding on edgeless detectors operation and development of a new issue - edgeless detectors with CTS on p-type Si.

Verbitskaya, E.; Eremin, V.; Ruggiero, G.

2011-12-01

157

Radiation damage resistance of reverse electrode ge coaxial detectors  

Microsoft Academic Search

Two high-purity germanium coaxial detectors, having opposite electrode configurations from one another, but fabricated from the same germanium crystal, were irradiated simultaneously with fast neutrons from an unmoderated ²²Cf source. Both detectors were 42 mm diam. The detector having the conventional electrode configuration was about 28 times more sensitive to radiaion damage than was the detector havng the p\\/sup +\\/

R. H. Pehl; N. W. Madden; J. H. Elliott; T. W. Raudorf; R. C. Trammell; L. S. Jr. Darken

1978-01-01

158

Circuitry for use with an ionizing-radiation detector. [power supply circuit and readout circuit  

Microsoft Academic Search

An improved system of circuitry for use in combination with an ionizing-radiation detector over a wide range of radiation levels includes a current-to-frequency converter together with a digital data processor for respectively producing and measuring a pulse repetition frequency which is proportional to the output current of the ionizing-radiation detector, a dc-to-dc converter for providing closely regulated operating voltages from

J. H. Marshall; T. M. Harrington

1976-01-01

159

Cross-Fertilization between Spallation Neutron Source and Third Generation Synchrotron Radiation Detectors  

SciTech Connect

Suffering presently from relatively low source strengths compared to synchrotron radiation investigations, neutron scattering methods will greatly benefit from the increase of instantaneous flux attained at the next generation of pulsed spallation neutron sources. In particular at ESS, the strongest projected source, the counting rate load on the detectors will rise by factors of up to 50-150 in comparison with present generic instruments. For these sources the detector requirements overlap partly with those for modern synchrotron radiation detectors as far as counting rate capability and two-dimensional position resolution are concerned. In this paper, examples of the current and forthcoming detector development, comprising e.g. novel solutions for low-pressure micro-strip gas chamber detectors, for silicon micro-strip detectors and for the related front-end ASICs and data acquisition (DAQ) systems, are summarized, which will be of interest for detection of synchrotron radiation as well.

Gebauer, B.; Schulz, Ch.; Alimov, S.S.; Wilpert, Th. [Hahn-Meitner-Instiut Berlin, Glienicker Str. 100, 14109 Berlin (Germany); Levchanovsky, F.V. [Hahn-Meitner-Instiut Berlin, Glienicker Str. 100, 14109 Berlin (Germany); Frank Laboratory of Neutron Physics, Joint Institute of Nuclear Research, 141980 Dubna (Russian Federation); Litvinenko, E.I.; Nikiforov, A.S. [Frank Laboratory of Neutron Physics, Joint Institute of Nuclear Research, 141980 Dubna (Russian Federation)

2004-05-12

160

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

NASA Astrophysics Data System (ADS)

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

161

9th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors  

NASA Astrophysics Data System (ADS)

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

162

Radiation damage studies of cerium-doped radiation-resistant lead glass detectors  

NASA Astrophysics Data System (ADS)

Optical absorption measurements have been made on unirradiated and irradiated samples of cerium oxide doped lead silicate particle detector glasses. The addition of CeO2 introduces one prominent and one weak absorption band near the ultraviolet transmission limit. However the CeO2 greatly reduces the rate of formation of the radiation induced absorption. Detector size blocks of lead glass with 0.0, 0.25, and 1.2 weight percent CeO2 were used to determine the energy resolution for 5 GeV electrons. The resolution deteriorates from 12 to 33% as the CeO2 changes from 0.0 to 1.2%. At these CeO2 levels, calculations indicate the yield of doped glass becomes superior to that of undoped glass for doses greater than 500 rad.

Adams, M. R.; Engelmann, R.; Grannis, P. D.; Horstkotte, J.; Godfrey, L.; Linn, S. L.; Marx, M. D.; Timms, J.; Tuts, P. M.; Willins, J.; Ahrens, L.; Aronson, S.; Levy, P. W.; Yamin, P.; Franzini, P.; Youssef, S.; Cutts, D.; Callas, J.

1985-08-01

163

Calculation of the relative efficiency of thermoluminescent detectors to space radiation  

Microsoft Academic Search

Thermoluminescent (TL) detectors are often used for measurements of radiation doses in space. While space radiation is composed of a mixture of heavy charged particles, the relative TL efficiency depends on ionization density. The question therefore arises: what is the relative efficiency of TLDs to the radiation present in space?In the attempt to answer this question, the relative TL efficiency

P. Bilski

164

Radiation monitoring and beam dump system of the OPAL silicon microvertex detector  

Microsoft Academic Search

The radiation monitoring and beam dump system of the OPAL silicon microvertex detector is described. This system was designed and implemented to measure the radiation dose over time scales varying from a millisecond to a year, and to induce a fast beam dump if the radiation exceeds a given threshold in dose and in dose rate within a very small

O. Biebel; S. Braibant; S. J. de Jong; R. Hammarström; R. Hilgers; A. K. Honma; P. Jovanovic; J. A. Lauber; H. A. Neal

1998-01-01

165

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

National Technical Information Service (NTIS)

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

R. B. Spielman

1990-01-01

166

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

SciTech Connect

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

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

2006-06-15

167

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

NASA Astrophysics Data System (ADS)

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

Lin, Shih-Yuin; Hu, B. L.

2006-06-01

168

Study of the charge collection efficiency of CdZnTe radiation detectors  

Microsoft Academic Search

The charge collection efficiency of CdZnTe radiation detectors with two different configurations: aSchottky diode detector and aresistive detector are compared. The average charge collection efficiencies for three different directions of irradiation (negative electrode,\\u000a positive electrode and perpendicular to the electric field) are calculated. The mobility-lifetime product of the CdZnTe substrates\\u000a is evaluated from the dependence of the measured spectra upon

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

1996-01-01

169

Crystallographic and metallurgical characterization of radiation detector grade cadmium telluride materials  

SciTech Connect

Radiation detector grade CdTe crystals are characterized by several crystallographic and metallurgical techniques including infrared microscopy, dislocation etch pitting and X-ray diffraction. Results are presented for a set of 50 detectors fabricated from an ingot produced by the High Pressure Bridgman method. Data on the temperature dependence of leakage current and pulse height analysis are presented, along with measurements of room temperature charge transport properties. Attempts to relate crystal structure to detector performance discussed.

Johnson, C.J.; Eissler, E.E.; Cameron, S.E. (II-VI, Inc., Saxonburg, PA (United States). eV Products Div.); Kong, Y.; Fan, S.; Jovanovic, S.; Lynn, K.G. (Brookhaven National Lab., Upton, NY (United States))

1993-01-01

170

Crystallographic and metallurgical characterization of radiation detector grade cadmium telluride materials  

SciTech Connect

Radiation detector grade CdTe crystals are characterized by several crystallographic and metallurgical techniques including infrared microscopy, dislocation etch pitting and X-ray diffraction. Results are presented for a set of 50 detectors fabricated from an ingot produced by the High Pressure Bridgman method. Data on the temperature dependence of leakage current and pulse height analysis are presented, along with measurements of room temperature charge transport properties. Attempts to relate crystal structure to detector performance discussed.

Johnson, C.J.; Eissler, E.E.; Cameron, S.E. [II-VI, Inc., Saxonburg, PA (United States). eV Products Div.; Kong, Y.; Fan, S.; Jovanovic, S.; Lynn, K.G. [Brookhaven National Lab., Upton, NY (United States)

1993-06-01

171

Radiation hardness of graded-gap Al x Ga 1? x As X-ray detectors  

Microsoft Academic Search

A study is presented of the influence of alpha-particle irradiation on the current and optical responses of graded-gap AlxGa1?xAs detectors for alpha-particle and X-ray radiation. The current response of the detector decreases by about an order of magnitude at an irradiation dose of 1010particles\\/cm2. Far better alpha-particle irradiation hardness is obtained from detectors with optical response. After an irradiation dose

A. Silenas; L. Dapkus; K. Pozela; J. Pozela; V. Juciene; V. Jasutis

2005-01-01

172

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

Microsoft Academic Search

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

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

1978-01-01

173

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

174

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

SciTech Connect

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

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

2010-06-01

175

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

National Technical Information Service (NTIS)

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 m...

B. A. Brunett B. L. Doyle R. B. James R. W. Olsen G. Vizkelethy

1998-01-01

176

Application of the blackbody radiation source for characteristics measurement of submillimeter low-temperature direct detectors  

Microsoft Academic Search

As is well-known characteristics measurement of submillimeter low-temperature direct detectors can be fulfilled using their signal response for the radiation of temperature swept blackbody. We describe a method using the Fredholm integral equation of first kind which solution gives possibility to derive direct detector spectral characteristic from the signal response dependence on temperature with acceptable accuracy. Then a noise equivalent

Alexander N. Vystavkin; Andrey V. Pestriakov; Eugeny A. Vinogradov

2006-01-01

177

Radiation Damage in Silicon Detectors Caused by Hadronic and Electromagnetic Irradiation  

Microsoft Academic Search

The report contains various aspects of radiation damage in silicon detectors subjected to high intensity hadron and electromagnetic irradiation. It focuses on improvements for the foreseen LHC applications, employing oxygenation of silicon wafers during detector processing (result from CERN-RD48). An updated survey on hadron induced damage is given in the first article. Several improvements are outlined especially with respect to

E. Fretwurst; G. Lindstrom; I. Pintilie; J. Stahl

2002-01-01

178

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

179

High tc superconductor radiation detector. Phase 1 final report. Report for 1 January30 September 1989  

Microsoft Academic Search

The goal of the project was to demonstrate the feasibility of building high Tc superconductor radiation detectors for use as high energy resolution spectrometers. Low Tc superconductor tunneling junctions were fabricated in an S-I-S configuration out of Sn and SnO2 and were capable of detecting alpha particles. This confirmed the concept of using tunneling junctions as radiation detectors. The primary

G. Entine; M. Soller

1989-01-01

180

Characterizing the radiation response of Cherenkov glass detectors with isotopic sources  

SciTech Connect

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

Hayward, J P [University of Tennessee, Knoxville (UTK); Hobbs, C. L. [University of Tennessee, Knoxville (UTK); Bell, Zane W [ORNL; Boatner, Lynn A [ORNL; Johnson, Rose E [ORNL; Ramey, Joanne Oxendine [ORNL; Jellison Jr, Gerald Earle [ORNL; Lillard, Cole R [ORNL; Ramey, Lucas A [ORNL

2012-01-01

181

The radiation tolerant readout system for srambased neutron detector  

Microsoft Academic Search

Bremsstrahlung gamma radiation and photoneutrons are produced during the operation of high energy linear accelerators. The functionality of electronic devices that are placed inside accelerator tunnels can be jeopardized because of the negative influence of generated radiation. Therefore, a radiation monitoring system able to gauge neutron fluence and gamma dose in real time was constructed. Radiation-sensitive dosimeters cooperate with a

D. Makowski; M. Grecki; B. Mukherjee; B. Swiercz; S. Simrock; A. Napieralski

2006-01-01

182

Photon Identification with Segmented Germanium Detectors in Low Radiation Environments  

SciTech Connect

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

Abt, I.; Caldwell, A.; Kroeninger, K.; Liu, J.; Liu, X.; Majorovits, B.; Stelzer, F. [MPI fuer Physik, Foehringer Ring 6, 80805 Munich (Germany)

2007-03-28

183

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

Microsoft Academic Search

The project goals are: (1) Develop CMT radiation detectors - Demonstrate feasibility (Phase 1 is complete) and Improve material properties and device performance; (2) This project will lead to novel radiation detectors - high detection efficiency, high energy-resolution, ambient-temperature operation, and low production cost; and (3) Such detectors are needed in areas of nonproliferation and national security for detection of

Bolotnikov

2009-01-01

184

TOPICAL REVIEW: Recent developments of diamond detectors for particles and UV radiation  

NASA Astrophysics Data System (ADS)

Diamond's many extreme properties, such as its radiation and corrosion resistance, large bandgap, high electron and hole mobility, make it an attractive semiconductor for UV and particle detectors. This paper reviews the properties that are exploited by the latest generation of detectors, such as the radiation hardness and detection mechanisms, and those which are less well understood, such as grain boundaries and priming effects. The UV and particle detectors and dosimeters that have been reported in the last few years are described and briefly assessed.

Mainwood, Alison

2000-09-01

185

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

SciTech Connect

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

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

1989-07-01

186

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

187

DEVELOPMENT OF CdZnTe RADIATION DETECTORS  

SciTech Connect

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

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

2011-10-23

188

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

NASA Astrophysics Data System (ADS)

The new SuperLHC upgrade will impose severe restrictions on the radiation hardness of silicon detectors since a maximum fluence of 10particles/cm is foreseen in the innermost region. Microstrip detectors have been fabricated in p-type high resistivity float zone silicon at CNM facilities, been irradiated at the TRIGA reactor in Ljubljana to a fluence of 10neutrons/cm and characterized at IFIC laboratory. The total collected charge before and after irradiation in the detectors has been measured by Sr90 beta source and by infrared laser illumination. The results show that even after this extreme radiation fluence, p-type substrate detectors collect 3500 electrons when biased at 800 V, which is enough charge to induce a measurable signal with standard readout electronics. P-type strip detectors could be suitable for the middle and even inner regions of sLHC.

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

2007-10-01

189

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

NASA Astrophysics Data System (ADS)

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

Moll, Michael

2010-04-01

190

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

Microsoft Academic Search

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

M. Laakso; P. Singh; E ENGELSJR; P. F. Shepard

1993-01-01

191

Some simple considerations on pulse shapes in radiation detectors  

NASA Astrophysics Data System (ADS)

Elementary ideas on pulse shapes from ionization chambers are reviewed. Ramo's theorem, and a plausible interpretation of it, are discussed and the results applied to semiconductor detectors. The complication of plasma formation is briefly referred to.

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

1984-04-01

192

Radiation hardness of a wide-bandgap material by the example of SiC nuclear radiation detectors  

NASA Astrophysics Data System (ADS)

A polarization effect characteristically occurs in detectors based on wide-bandgap materials at considerable concentrations of radiation defects. The appearance of an electromotive force in the bulk of a detector is due to the long-term capture of carriers at deep levels related to radiation centers. The kinetics and strength of the polarization field have been determined. The carrier capture by the radiation centers can be controlled by varying the detector temperature, with a compromise reached at the “optimal” temperature between the generation current and the position of the deepest of the levels whose contribution to the loss of charge via capture is negligible. It has been found that the depth of a level of this kind (related to the energy gap width) is close to 1/3, irrespective of a material. The optimal temperatures are strictly individual for materials.

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

2012-05-01

193

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

194

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

SciTech Connect

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

Vizkelethy, Gyorgy

2010-07-01

195

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

SciTech Connect

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

Vizkelethy, Gyorgy

2009-10-01

196

Influence of radiation on Voltage Terminating Structure of silicon relativistic particle detectors  

NASA Astrophysics Data System (ADS)

Semiconductor radiation detectors are widely applied in high energy physics experiments. The largest particle colliders use silicon detectors with the total area of hundreds square meters that enhances the requirement to their stable long-term operation. This is provided by incorporating the floating p+ rings surrounding the sensitive area of the p+-n-n+ detectors (VTS - Voltage Termination Structure), that prevents an electric breakdown. The physical model of VTS operation in high-resistivity p+-n-n+ silicon radiation detectors developed in the study uses an approach of the current injection through the ring spacings of VTS that may occur under a certain electric field distribution. This leads to a strict stabilization of the ring potentials. Investigation of the potential distribution in VTS of silicon detectors irradiated with 1 MeV neutrons up to a fluence of 5×1015 neq/cm2 was carried out. It was shown that the change of the electric field profile in the detector bulk with increasing radiation fluence is a key factor for the potential distribution. At fluences less than 5×1014 neq/cm2 the potential distribution in VTS is governed by the punchthrough mechanism, whereas at higher fluences it is controlled by the bulk generation current and interaction with radiation induced deep levels.

Fadeeva, N.; Eremin, V.; Verbitskaya, E.; Terukov, E.

2013-08-01

197

Calculations for a disk source and a general detector using a radiation vector potential  

NASA Astrophysics Data System (ADS)

A closed form expression for a radiation vector potential is derived for a generalized disk radiation source. By applying Stokes's theorem the surface integral for the radiation flux into a general detector is converted into a much simpler line integral of the vector potential around the edge of the detector. This line integral can be easily evaluated for general detector geometry and general location and angular orientation relative to the disk source. For a number of cases the line integral reduces to integrals of Bessel functions which give various generalizations of Ruby's formula. Explicit formulas and numerical results for the geometric efficiency are given for circular and elliptical detectors displaced and rotated relative to the disk source. Detectors with general polygonal boundaries are considered and formulas and sample numerical results are given. For uniform surface emissivity the corresponding formulas for a disk detector and a general planar source are easily obtained. Formulas are also obtained for a scalar radiation potential and some limitations for its applicability are identified.

Conway, John T.

2008-04-01

198

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

199

Radiation-hard semiconductor detectors for SuperLHC  

Microsoft Academic Search

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

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

2005-01-01

200

Radiation detectors and sources enhanced with micro\\/nanotechnology  

Microsoft Academic Search

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

Chad Michael Whitney

2009-01-01

201

Characterization and TCAD modelling of termination structures for silicon radiation detectors  

Microsoft Academic Search

We have recently proposed a novel junction termination structure for silicon radiation detectors, featuring all-p-type multiguard and scribe-line implants, with metal field-plates completely covering the gap between the implanted rings. The structure is intended for detector long-term stability enhancement even in adverse ambient conditions and for fabrication-process simplification. A thorough static characterization, including stability measurements in varying humidity conditions, has

S. Dittongo; M. Boscardin; L. Bosisio; M. Ciacchi; G.-F. Dalla Betta; P. Gregori; C. Piemonte; I. Rachevskaia; S. Ronchin; N. Zorzi

2004-01-01

202

Surface Barrier Silicon Radiation Detectors Improved by Using a Tungsten Oxide for the Surface Stability  

Microsoft Academic Search

The improvements of surface barrier silicon radiation detectors have been accomplished by evaporating a tungsten oxide material on the surface of n-type silicon substrate as the surface stabilized film before gold electrode deposition, the structure of which is metal-metal oxide-semiconductor type. The stability and electrical characteristics of improved silicon detectors are better than those of the conventional surface barrier silicon

Y. Ishizuka; C. Kim; Y. Kim; S. Ohkawa; K. Husimi; S. Osada; M. Ishii

1986-01-01

203

A Radiation Imaging Detector Made by Postprocessing a Standard CMOS Chip  

Microsoft Academic Search

An unpackaged microchip is used as the sensing element in a miniaturized gaseous proportional chamber. This letter reports on the fabrication and performance of a complete radiation imaging detector based on this principle. Our fabrication schemes are based on wafer-scale and chip-scale postprocessing. Compared to hybrid-assembled gaseous detectors, our microsystem shows superior alignment precision and energy resolution, and offers the

Víctor Manuel Blanco Carballo; Maximilien Chefdeville; Martin Fransen; Graaf van der Harry; Joost Melai; Cora Salm; Jurriaan Schmitz; Jan Timmermans

2008-01-01

204

Radiative processes for Rindler and accelerating observers and the stress-tensor detector  

Microsoft Academic Search

We consider a monopole detector interacting with a massive scalar field. The\\u000aradiative processes are discussed from the accelerated frame point of view.\\u000aAfter this, we obtain the Minkowski vacuum stress tensor measured by the\\u000aaccelerated observer using a non-gravitational stress tensor detector as\\u000adiscussed by Ford and Roman (PRD 48, 776 (1993)). Finally, we analyse radiative\\u000aprocesses of the

R. De Paola; N. F. Svaiter

1996-01-01

205

Cumulative effects of Te precipitates in CdZnTe radiation detectors  

Microsoft Academic Search

High-quality radiation detector-grade CdZnTe material is free from large-scale defects, such as grain boundaries, twins, and large Te or Cd inclusions (>50?m), although it usually contains high concentrations of uniformly distributed Te inclusions and precipitates, typically of ?20-?m-diameter size or smaller. We address the effects of the small-size Te precipitates on charge collection in CZT detectors, the significance of which

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

2007-01-01

206

Cumulative effects of Te precipitates in CdZnTe radiation detectors  

Microsoft Academic Search

High-quality radiation detector-grade CdZnTe material is free from large-scale defects, such as grain boundaries, twins, and large Te or Cd inclusions (>50 mum), although it usually contains high concentrations of uniformly distributed Te inclusions and precipitates, typically of ˜20-mum-diameter size or smaller. We address the effects of the small-size Te precipitates on charge collection in CZT detectors, the significance of

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

2007-01-01

207

Network deployment of radiation detectors with physics-based detection probability calculations  

Microsoft Academic Search

We describe a model for deploying radiation detectors on a transportation network consisting of two adversaries: a nuclear-material\\u000a smuggler and an interdictor. The interdictor first installs the detectors. These installations are transparent to the smuggler,\\u000a and are made under an uncertain threat scenario, which specifies the smuggler’s origin and destination, the nature of the\\u000a material being smuggled, the manner in

Nedialko B. Dimitrov; Dennis P. Michalopoulos; David P. Morton; Michael V. Nehme; Feng Pan; Elmira Popova; Erich A. Schneider; Gregory G. Thoreson

208

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

209

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

PubMed

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

Gronchi, Claudia C; Caldas, Linda V E

2012-08-11

210

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

SciTech Connect

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

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

2010-10-26

211

Evaluating the performance of semiconductor radiation detectors through static charge analysis  

SciTech Connect

This paper presents a new approach to analyzing semiconductor radiation detectors based on considering: (1) static charge when all free charge has been collected and (2) capacitances between electrodes and trapped charge within the crystal. It avoids any direct consideration of free charge motion in the detector. The validity of this static charge approach is established by using it to derive the Hecht equation. Its general usefulness is demonstrated by employing it to examine detectors with well-known alternative electrode geometries and obtaining useful new insight into their operating mechanisms. This new approach should provide a useful and intuitive visualization tool to aid in designing new detector configurations and establishing models for analysis of detectors with more complex geometries.

Lingren, C.L.; Butler, J.F. [Digirad Corp., San Diego, CA (United States)

1998-06-01

212

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

SciTech Connect

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

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

2012-05-15

213

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

214

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

215

Polycrystalline diamond position sensitive detector for excimer laser UV radiation  

Microsoft Academic Search

To overcome any difficulty related to the fabrication of diamond ultraviolet (UV) sensors based on p–n junction, in this work we describe the realisation and characterisation of a very simple chemical vapour deposited diamond position sensitive detector based on a voltage-division structure. The photosensor, tested under UV excimer laser illumination, shows a non-linearity of the output signal vs. the beam

S. Salvatori; G. Mazzeo; G. Conte; M. C. Rossi; V. Ralchenko

2004-01-01

216

Precursor Measurements of the Mars Surface Radiation Environment with 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 analyzer to fly as part of the NASA 2009 Mars Science Laboratory MSL Mission RAD will detect and analyze relevant energetic particle species p n He 2 Z 26 incident on the Martian surface including direct and indirect radiation created both in the atmosphere and the regolith Fully characterizing and understanding the radiation environment is fundamental to quantitatively assessing the habitability of Mars and an essential precursor measurement for future manned Mars missions This talk will provide an overview of the RAD instrument and its scientific objectives for the MSL mission

Hassler, D. M.; Wimmer-Schweingruber, R. F.; Beaujean, R.; Bottcher, S.; Burmeister, S.; Cucinotta, F.; Muller-Mellin, R.; Posner, A.; Rafkin, S.; Reitz, G.; Rad Team

217

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

218

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

SciTech Connect

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

LI,Z.

2002-09-09

219

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

Microsoft Academic Search

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

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

2009-01-01

220

Comprehensive modeling of bulk-damage effects in silicon radiation detectors  

Microsoft Academic Search

In this paper, the issue of numerical modeling of radiation-damaged silicon devices is discussed, with reference to radiation detectors employed in high-energy physics experiments. Since the actual physical picture is far too complex to be accounted for at a first-principle (i.e., defect kinetics) level and not yet fully understood, a hierarchical approach has been followed looking for a suitable approximation

Daniele Passeri; Paolo Ciampolini; Gian Mario Bilei; Francesco Moscatelli

2001-01-01

221

Innovative uses for conventional radiation detectors via pulse shape analysis  

SciTech Connect

In this report we have discussed two applications for digital pulse shape analysis in Ge detectors: Compton suppression and {gamma}-ray imaging. The Compton suppression aspect has been thoroughly studied during the past few years, and a real-time, laboratory-prototype system has been fielded. A summary of results from that set up have been discussed here. The {gamma}-ray imaging aspect, while not yet developed experimentally, looks very promising theoretically as the simulations presented here have shown. Experimental work currently underway at Berkeley (as discussed in section 4.3) should help further guide us towards the proper developmental path.

Beckedahl, D; Blair, J; Friensehner, A; Kammeraad, J E; Schmid, G

1999-03-03

222

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

SciTech Connect

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

Afanasyev, V. I. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Kozlovskii, S. S.; Makar'in, D. V. [St. Petersburg State Polytechnical University (Russian Federation); Mel'nik, A. D.; Mironov, M. I.; Nesenevich, V. G.; Petrov, M. P.; Petrov, S. Ya.; Chernyshev, F. V. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

2010-05-15

223

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

224

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

DOEpatents

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

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

1987-02-27

225

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

226

Development of radiation tolerant semiconductor detectors for the Super-LHC  

NASA Astrophysics Data System (ADS)

The envisaged upgrade of the Large Hadron Collider (LHC) at CERN towards the Super-LHC (SLHC) with a 10 times increased luminosity of 1035 cm-2 s-1 will present severe challenges for the tracking detectors of the SLHC experiments. Unprecedented high radiation levels and track densities and a reduced bunch crossing time in the order of 10 ns as well as the need for cost effective detectors have called for an intensive R&D program. The CERN RD50 collaboration “Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders” is working on the development of semiconductor sensors matching the requirements of the SLHC. Sensors based on defect engineered silicon like Czochralski, epitaxial and oxygen enriched silicon have been developed. With 3D, Semi-3D and thin detectors new detector concepts have been evaluated and a study on the use of standard and oxygen enriched p-type silicon detectors revealed a promising approach for radiation tolerant cost effective devices. These and other most recent advancements of the RD50 collaboration are presented.

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

2005-07-01

227

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

228

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

229

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

230

Cherenkov detector of 90Sr based on aerogel as radiator  

Microsoft Academic Search

90Sr is a highly radiotoxic fission product, which may pollute the environment following an accident in a nuclear power plant. It is a pure ? emitter and thus difficult to detect by standard methods. Recent progress in silica aerogel production, as well as the new multianode photomultiplier tubes (PMTs), offer possibilities for the detection of 90Sr, based on Cherenkov radiation

R. Pestotnik; S. Korpar; P. Krizan; R. Dolenec

2008-01-01

231

VALIDATION TESTING OF ANSI\\/IEEE N42.49 STANDARD REQUIREMENTS FOR PERSONAL EMERGENCY RADIATION DETECTORS  

Microsoft Academic Search

Various radiation detectors including electronic personal emergency radiation detectors (PERDs), radiochro- mic film cards and thermoluminescent dosimeters (TLDs) were used to validate a subset of the radiological test require- ments listed in the American National Standards Institute\\/The Institute of Electrical and Electronic Engineers (ANSI\\/IEEE) N42.49 standard. The subset of tests included the following: comparing the readout of the detectors with

L. Pibida; R. Minniti

2010-01-01

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  

NASA Astrophysics Data System (ADS)

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

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

2008-10-01

234

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

SciTech Connect

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

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

2008-10-15

235

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

236

Isolation of Highly Doped Implants on Low-Doped Active Layers for CMOS Radiation Drift Detectors  

Microsoft Academic Search

A method to avoid punchthrough between highly doped implants, built on low-doped substrates or epitaxial layers, is proposed. The technique, which is similar to other previously used in scientific pixel detectors, is here applied in a VLSI CMOS standard technology, to design electrically isolated pixels for radiation or particle detection using the source\\/drain implants as collecting electrodes. The isolation principle

Giacomo Langfelder

2009-01-01

237

Using thermal radiation detectors for studying aerodynamic heating at hypersonic flow velocities  

Microsoft Academic Search

The thermal fluxes of a cylindrical nozzle with an internal cavity have been measured using a thermal radiation detector. It is shown that heat transfer is significantly intensified in a finely dispersed heat-insulating material due to the mechanical and acoustic effect of hypersonic flow. Intense generation of heat fluxes also occurs in conical cavities forming the heat-sensitive surface of the

O. A. Gerashchenko; E. I. Averkov; M. A. Goldfeld; G. A. Kiselev; I. I. Klimenko

1986-01-01

238

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.

239

Design and Implementation of a Detector for High Flux Mixed Radiation Fields  

Microsoft Academic Search

The main purpose of the LHC Beam Loss Monitoring (BLM) system is the active protection of the LHC accelerators' elements against the quench of superconducting magnets and the damage of equipment caused by the loss of circulating protons. The lost protons initiate a shower of secondary particles, which deposit their energy in the equipment and partly in a radiation detector.

Daniel Kramer; Bernd Dehning; Miroslav Sulc

2008-01-01

240

Development of 500 MHz MultiChannel Readout Electronics for Fast Radiation Detectors  

Microsoft Academic Search

We describe the development of readout electronics for fast radiation detectors that digitize signals at a rate of 500 MHz, process the digital data stream to measure pulse heights, bin the results in on-board MCA spectra, and optionally capture waveforms for pulse shape analysis. The electronics are targeted for applications requiring good energy resolution and precise timing, for example life

Wolfgang Hennig; Stephen J. Asztalos; Dimitry Breus; Konstantin Sabourov; William K. Warburton

2010-01-01

241

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

Microsoft Academic Search

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

Daryl R. Myers

2010-01-01

242

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

PubMed

It was shown that the detector of extremely weak radiation with selectively increased sensitivity to the nonelectromagnetic, including the gravitational component of the spectrum of active physical fields can be used as the basis for constructing a variometer of gravitational field of a new type. PMID:11605376

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

243

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

244

Improvement of Spectral Characteristics of High-Resistance Thermal Radiation Detectors.  

National Technical Information Service (NTIS)

An improved method is proposed for the construction of high-resistance thermal-radiation detectors which use gold-black as the infrared absorber. Because of its poor adhesive properties, gold-black cannot be deposited directly on the sensitive material, b...

L. S. Kremenchugskii V. S. Lysenko A. F. Malnev O. V. Roitsina

1967-01-01

245

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

SciTech Connect

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

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

1999-01-01

246

Metal-nitride-oxide-semiconductor detector for an ionizing radiation dosimeter  

Microsoft Academic Search

This report describes the work completed by the author for his Master of Science thesis at the Air Force Institute of Technology. The topic and funds were provided by the Air Force Weapons Laboratory. A method of radiation dosimetry using a Metal-Nitride-Oxide-Semiconductor (MNOS) device as the detector was developed and partially evaluated. The MNOS devices are capable of measuring doses

R. G. Fraass

1978-01-01

247

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

Microsoft Academic Search

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

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

248

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

249

State-of-the-art radiation detectors for medical imaging: Demands and trends  

NASA Astrophysics Data System (ADS)

Over the last half-century a variety of significant technical advances in several scientific fields has been pointing to an exploding growth in the field of medical imaging leading to a better interpretation of more specific anatomical, biochemical and molecular pathways. In particular, the development of novel imaging detectors and readout electronics has been critical to the advancement of medical imaging allowing the invention of breakthrough platforms for simultaneous acquisition of multi-modality images at molecular level. The present paper presents a review of the challenges, demands and constraints on radiation imaging detectors imposed by the nature of the modality and the physics of the imaging source. This is followed by a concise review and perspective on various types of state-of-the-art detector technologies that have been developed to meet these requirements. Trends, prospects and new concepts for future imaging detectors are also highlighted.

Darambara, Dimitra G.

2006-12-01

250

Radiation damage effects in Si materials and detectors and rad-hard Si detectors for SLHC  

Microsoft Academic Search

Silicon sensors, widely used in high energy and nuclear physics experiments, suffer severe radiation damage that leads to degradations in sensor performance. These degradations include significant increases in leakage current, bulk resistivity, space charge concentration, and free carrier trapping. For LHC applications, where the total fluence is in the order of 1 × 1015 neq\\/cm2 for 10 years, the increase

Z. Li

2009-01-01

251

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

SciTech Connect

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

Knoll, G.F.

1995-11-01

252

Photon detector performance and radiator scintillation in the HADES RICH  

Microsoft Academic Search

We report the performance of a VUV-sensitive MWPC with a pad cathode covered by a solid CsI photon converter. Cherenkov photons produced by relativistic 12C ions in a MgF2 radiator have been detected with 95% single photo electron efficiency. In the HADES design a resulting figure of merit N0 > 66 promises proper operation of the RICH as a fast

R. Gernhäuser; B. Bauer; J. Friese; J. Homolka; A. Kastenmüller; P. Kienle; H.-J. Körner; P. Maier-Komor; M. Münich; R. Schneider; K. Zeitelhack

1996-01-01

253

A new type of sensitive semiconductor detectors of terahertz radiation  

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

254

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 analyzer to fly as part of the NASA 2009 Mars Science Laboratory MSL Mission RAD will detect and analyze relevant energetic particle species p n He 2 Z 27 incident on the Martian surface including direct and indirect radiation created both in the atmosphere and the regolith Fully characterizing and understanding the radiation environment is fundamental to quantitatively assessing the habitability of Mars and an essential precursor measurement for future manned Mars missions This talk will provide an overview of the RAD instrument and its scientific objectives for the MSL mission

Hassler, D. M.; Wimmer-Schweingruber, R. F.; Beaujean, R.; Bottcher, S.; Burmeister, S.; Cucinotta, F.; Muller-Mellin, R.; Posner, A.; Rafkin, S.; Reitz, G.; Rad Team

255

Radiation monitoring and beam dump system of the OPAL silicon microvertex detector  

NASA Astrophysics Data System (ADS)

The radiation monitoring and beam dump system of the OPAL silicon microvertex detector is described. This system was designed and implemented to measure the radiation dose over time scales varying from a millisecond to a year, and to induce a fast beam dump if the radiation exceeds a given threshold in dose and in dose rate within a very small time interval. The system uses reverse-biased silicon diodes as sensitive elements and good stability is achieved by AC coupling of the amplifiers to the sensors.

Biebel, O.; Braibant, S.; de Jong, S. J.; Hammarström, R.; Hilgers, R.; Honma, A. K.; Jovanovic, P.; Lauber, J. A.; Neal, H. A.

1998-02-01

256

A High Purity Germanium Diode Operated as a Radiation Detector in Liquid Argon  

NASA Astrophysics Data System (ADS)

Guided by the pioneering work of the GERDA Collaboration on next generation neutrinoless double beta decay experiments, we have begun an investigation of the operation of bare germanium (Ge) radiation detectors in liquid argon. Liquid argon (LAr) serves both as a cryogenic medium to cool the Ge crystal and as a scintillating veto shield. The veto shield has two distinct functions. First, the LAr tags and rejects radiation from external sources. Second, the LAr suppresses the Compton background arising from gamma-rays that only partly deposit their energy inside the Ge crystal. Current results from operating the Ge crystal as a radiation detector in LAr are presented. The value of this type of radiation detector is discussed regarding two potential applications. The first is the need for increasingly low-background, high-sensitivity radiation counters. The second is the next generation of neutrinoless double beta decay experiments currently under development. The Majorana Experiment is one such project that will benefit from this line of research.

Orrell, John L.

2005-04-01

257

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

PubMed

For radiation monitoring at the site of nuclear power plant accidents such as Fukushima Daiichi, radiation detectors not only for gamma photons but also for alpha and beta particles are needed because some nuclear fission products emit beta particles and gamma photons and some nuclear fuels contain plutonium that emits alpha particles. We developed a radiation detector that can simultaneously monitor alpha and beta particles and gamma photons for radiation monitoring. The detector consists of three-layered scintillators optically coupled to each other and coupled to a photomultiplier tube. The first layer, which is made of a thin plastic scintillator (decay time: 2.4 ns), detects alpha particles. The second layer, which is made of a thin Gd(2)SiO(5) (GSO) scintillator with 1.5 mol.% Ce (decay time: 35 ns), detects beta particles. The third layer made of a thin GSO scintillator with 0.4 mol.% Ce (decay time: 70 ns) detects gamma photons. By using pulse shape discrimination, the count rates of these layers can be separated. With individual irradiation of alpha and beta particles and gamma photons, the count rate of the first layer represented the alpha particles, the second layer represented the beta particles, and the third layer represented the gamma photons. Even with simultaneous irradiation of the alpha and beta particles and the gamma photons, these three types of radiation can be individually monitored using correction for the gamma detection efficiency of the second and third layers. Our developed alpha, beta, and gamma detector is simple and will be useful for radiation monitoring, especially at nuclear power plant accident sites or other applications where the simultaneous measurements of alpha and beta particles and gamma photons are required. PMID:22128972

Yamamoto, Seiichi; Hatazawa, Jun

2011-11-01

258

GaAs semi-insulator detector for gamma and charged-particle radiation  

NASA Astrophysics Data System (ADS)

Silicon positive-intrinsic-negative (p-i-n) diodes have been used in plasma diagnostics by the Los Alamos and Lawrence Livermore National Laboratories (LANL and LLNL) since the early seventies. Since the response bandwidth of these detectors is relatively poor (typically, approximately 5 ns FWHM for 1 cm(superscript 2) sensitive area and 250 micrometers depletion depth), they are too slow for high-speed applications. GaAs photoconductive detectors (PCD) have been developed since the early eighties at LANL and later at LLNL, and can be tailored by judicious neutron damage to provide the required high-speed bandwidth. Unfortunately, for surface absorbed or non-penetrating radiation, we have discovered that the PCD sensitivity is not flat across its gap, where the incident radiation is perpendicular to the bias electric field. This response non-uniformity can lead to erroneous measurements in cases where the radiation is spatially varying. To overcome this problem, we reoriented the GaAs chip to allow the radiation to be incident through the electrode and parallel to the bias electric field. Then to increase bandwidth, we doped the GaAs crystal with chromium to create trapping sites and provide large resistivity (approximately 10(superscript 9) (Omega) cm), thus creating a semi-insulator detector (SID). We present and discuss the merits of the SID versus PCD and p-i-n diode by showing pulse response data of each detector characterized with 16 MeV endpoint gamma and electron radiation created by the EG&G/EM linear accelerator (Linac) and 5 to 16.5 MeV proton radiation produced by the LLNL Tandem Van de Graaff (TVDG). Application of the SID in Compton electron spectrometry also is discussed.

Moy, Kenneth J.; Wang, Ching L.; Flatley, John E.; Pocha, Michael D.; Davis, Brent A.; Wagner, Ronald S.

1992-12-01

259

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

260

A high-dynamic and accurate electromagnetic radiation and thermal energy detector for planetary studies  

NASA Astrophysics Data System (ADS)

The radio meter has been broadly applied for the study of the Total Solar Irradiance (TSI). As the electromagnetic radiation is the main external climate driving force of our planet: Earth, the Imbalance of the Earth's Radiation Budget (IERB) is a key to better understanding our climate system. The PICARD mission is to study the Sun-Earth's climate connections. With the opportunity of the PICARD mission, we have developed a Bolometric Oscillation Sensor (BOS), which are currently flying side by side with the radiometer SOlar Variability for Picard (SOVAP-an updated instrument of DIARAD/VIRGO on SOHO) to study the solar constant as well as the radiation of the Earth. The BOS sensor is composed with two detectors, the light mass detector (m1), which is rapidly response to the thermal-flux change, and the heavy mass detector (m2), which is slowly modulated by the electromagnetic energy. In addition, the m1 detector can stand alone to precisely monitor the ambient temperature. The original goal of the BOS-PICARD is to study the irradiance of the Sun's and the Earth's. After nearly two year's observations, the variations of Long-Wave radiation of the Earth can be well determined from the BOS measurements. It confirms that the BOS can be applied to measure the electromagnetic radiation near the infrared. Encouraged by these results, we are now working on a second generation of the BOS sensor for the nano-satellite project and future planetary missions. The new sensor will be able to determine the albedo (visible), infrared radiation as well as to detect the thermal initial of objective target either by the remote sensing on-board satellite or by the in-situ measurement setting up in the Lander.

Zhu, P.; Karatekin, O.; Noel, J.-P.; van Ruymbeke, M.; Dehant, V.

2012-04-01

261

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

SciTech Connect

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

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

2011-11-15

262

Intravascular radiation detectors for the detection of vulnerable atheroma.  

PubMed

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

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

2006-04-18

263

Effects of Te inclusions on the performance of CdZnTe radiation detectors  

SciTech Connect

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

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

2008-10-19

264

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

SciTech Connect

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

Sadler, Lorraine E.

2008-10-01

265

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

NASA Astrophysics Data System (ADS)

The proposed luminosity upgrade of the Large Hadron Collider (S-LHC) at CERN will demand the innermost layers of the vertex detectors to sustain fluences of about 1016 hadrons/cm2. Due to the high multiplicity of tracks, the required spatial resolution and the extremely harsh radiation field new detector concepts and semiconductor materials have to be explored for a possible solution of this challenge. The CERN RD50 collaboration “Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders” has started in 2002 an R&D program for the development of detector technologies that will fulfill the requirements of the S-LHC. Different strategies are followed by RD50 to improve the radiation tolerance. These include the development of defect engineered silicon like Czochralski, epitaxial and oxygen-enriched silicon and of other semiconductor materials like SiC and GaN as well as extensive studies of the microscopic defects responsible for the degradation of irradiated sensors. Further, with 3D, Semi-3D and thin devices new detector concepts have been evaluated. These and other recent advancements of the RD50 collaboration are presented and discussed.

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

2005-10-01

266

Effects of radiations on the characteristics of alpha and fission tracks in CR-39 detectors  

NASA Astrophysics Data System (ADS)

The effects of neutron, gamma and alpha radiations on the alpha and fission fragment tracks registration and revelation properties of CR-39 detectors (CR-39 and CR-39(DOP) were studied. It was found that the ratio of the bulk etch rate of irradiated to unirradiated (VG(irr.)/VG(unirr.) detectors is linearly dependent on dose. An exponential decrease in fission track densities with increase in neutron fluence was observed. The ratio of VG(irr.)/VG(unirr.) was found to be high in CR-39 than that in CR-39(DOP) exposed to the same reactor neutron fluence. The decrease in fission track densities with increase in neutron fluence was observed to be faster in CR-39 than in CR-39(DOP). This indicates that doping with dioctyl phthalate improves the radiation resistance of CR-39 detectors. It was observed that in detectors exposed to an alpha flux of the order of 9.36 ? 106 / cm2, the fission track density was reduced by 11% and thereafter it remained constant. The results also indicate that thermal neutron fluence up to 7.01 ?1011 neutrons/cm2 does not affect the alpha and fission track densities. I.R. spectra were also studied to find out the nature of chemical changes produced by these radiations on CR-39.

Pandey, A. K.; Sharma, R. C.; Padalkar, S. K.; Kalsi, P. C.; Iyer, R. H.

1994-06-01

267

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

268

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

SciTech Connect

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

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

2011-08-07

269

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

SciTech Connect

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

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

2010-06-29

270

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

SciTech Connect

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

V. Popov

2011-01-01

271

One dimensional X-ray MSGC detector for synchrotron radiation experiments and medical imaging  

NASA Astrophysics Data System (ADS)

We present results from the prototype of a one dimensional detector based on a micro-strip gas chamber (MSGC). A 100 channel MSGC was tested in a high pressure volume filled with Xe-CO2 (80-20) mixture. Individual electronic channels counting photons absorbed in the sensitive volume were connected to each anode strip. A spatial resolution of about 200 ?m (FWHM) and rate capability of 200 kHz/channel were achieved for 18 keV X-rays. The detector was tested in a synchrotron radiation (SR) beam at the VEPP-3 storage ring, and some preliminary results from these tests are presented. We also discuss the next steps towards the construction of a larger MSGC detector for medical imaging and SR experiments.

Baru, S. E.; Neustroev, V. V.; Papanestis, A.; Porosev, V. V.; Savinov, G. A.; Shekhtman, L. I.

1998-02-01

272

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

SciTech Connect

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

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

1989-09-01

273

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

274

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

275

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

276

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

277

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

NASA Astrophysics Data System (ADS)

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

Myers, Daryl R.

2010-08-01

278

Employing Carbon Nano-Tubes in New Nano-Structured Radiation Detectors  

NASA Astrophysics Data System (ADS)

So far, electronics has growth up together with the possibility of designing electronic circuits based on the semi conductive properties of silicon. However, the last two decades has been characterized by the explosion of techniques allowing the observation and manipulation of materials at the nanometric length scale. For many applications, the role of silicon is thus turning towards that of a well known substrate whose surface is modified and decorated, at the nano-scale, with other materials. This configuration often represents a nano-structured material. Among all the materials involved in nano-science and nano-technology, Carbon Nano-Tubes (CNTs) have already been employed into a huge number of applications. Here we report the last results in designing a new radiation detector based on CNTs that appears promising for the aim of broadening the detection range of solid state radiation detectors.

Ambrosio, A.; Ambrosio, M.; Aramo, C.; Carillo, V.; Guarino, F.; Maddalena, P.; Grossi, V.; Passacantando, M.; Santucci, S.; Valentini, A.

2010-04-01

279

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

280

Micromachined silicon bolometers as detectors of soft X-ray, ultraviolet, visible and infrared radiation  

Microsoft Academic Search

This paper presents the development of micromachined thin-film silicon microbolometers which can be used for detection of soft X-ray, UV, visible and infrared radiation. The detector structure is a 1 ?m thick polysilicon\\/Si3N4 membrane suspended over a cavity. This structure has been obtained by anisotropic etching of silicon with a previously deposited polysilicon\\/Si3N4 sandwich. Alternatively, porous silicon has been used

L Dobrza?ski; E Nossarzewska-Or?owska; Z Nowak; J Piotrowski

1997-01-01

281

An improved all-p-type multiguard termination structure for silicon radiation detectors  

Microsoft Academic Search

A junction termination structure for silicon radiation detectors is investigated, featuring all-p-type multiguard and scribe-line implants, with metal field-plates providing complete coverage of the oxide upper surface above non-implanted regions. The sensitive. interface between oxide and n-type substrate is thus electrostatically screened from the external environment, holding the promise for improved long-term stability of the device and excellent insensitivity to

Maurizio Boscardin; Luciano Bosisio; Andrea Candelori; G.-F. D. Bette; Selenia Dittongo; Paolo Gregori; Aleksej Litovchenko; Claudio Piemonte; Irina Rachevskaia; S. Ronchin; G. Verzellesi; N. Zorzi

2002-01-01

282

Using thermal radiation detectors for studying aerodynamic heating at hypersonic flow velocities  

NASA Astrophysics Data System (ADS)

The thermal fluxes of a cylindrical nozzle with an internal cavity have been measured using a thermal radiation detector. It is shown that heat transfer is significantly intensified in a finely dispersed heat-insulating material due to the mechanical and acoustic effect of hypersonic flow. Intense generation of heat fluxes also occurs in conical cavities forming the heat-sensitive surface of the radiometer.

Gerashchenko, O. A.; Averkov, E. I.; Goldfeld, M. A.; Kiselev, G. A.; Klimenko, I. I.

283

Performance of lead iodide nuclear radiation detectors with the introduction of rare earth elements  

NASA Astrophysics Data System (ADS)

Lead iodide has been recognized as a promising material for room temperature radiation detectors. It has a wide band-gap (˜ 2.3 eV), high atomic numbers (82, 53) and it is environmentally very stable compared to mercuric iodide. Electrical and optical properties of lead iodide grown crystals purified under the influence of selected rare earth elements have been investigated. Photo-luminescence and capacitance-voltage measurements have been performed using different rare earth elements.

Hassan, Mahmoud; Matuchova, Marie; Zdansky, Karel

2006-01-01

284

Silicon PIN radiation detectors with on-chip front-end junction field effect transistors  

Microsoft Academic Search

We report on the latest results obtained from the development of a fabrication technology for PIN radiation detectors with on-chip front-end junction field effect transistors (JFETs) integrated on high-resistivity, FZ silicon. P-doped polysilicon back-side gettering prevented carrier lifetime degradation in spite of the relatively high thermal budget characterizing the fabrication process, allowing very low leakage currents (?1nA\\/cm2 at full depletion)

G. F. Dalla Betta; G. Verzellesi; M. Boscardin; L. Bosisio; G. U. Pignatel; L. Ferrario; M. Zen; G. Soncini

1998-01-01

285

Radiation hardness of minimum ionizing particle detectors based on SiC p+n junctions  

Microsoft Academic Search

In this work we analyzed the radiation hardness of SiC p+\\/n diodes used as minimum ionizing particle (MIP) detectors after very high 1 MeV neutron fluences. The diode structure is based on ion implanted p+ emitter in an n-type epilayer with thickness equal to 55 ?m and donor doping ND = 2×1014 cm-3. The diode breakdown voltages were above 1000

F. Moscatelli; A. Scorzoni; A. Poggi; M. Bruzzi; S. Sciortino; S. Lagomarsino; G. Wagner; R. Nipoti

2005-01-01

286

Study of Beam-Induced Radiation in the CMS Detector at the Large Hadron Collider  

Microsoft Academic Search

The intense radiation environment at the Large Hadron Collider (CERN) at the design energy of &surd;s =14 TeV and luminosity of 10^34 cm-2 sec-1 poses unprecedented challenges for safe operation and performance quality of the silicon tracker detectors in the CMS and ATLAS experiments. The silicon trackers are crucial for the physics at the LHC experiments, and the inner layers,

Anil Singh; Pushpalatha Bhat; Suman Beri; Nikolai Mokhov

2008-01-01

287

Development of Detectors for Measurement of Neutron and Gamma-radiation from Laser-Produced Plasma  

NASA Astrophysics Data System (ADS)

The paper describes the development of the detectors widely used in the nuclear physics for measurement of neutron and gamma-radiation in laser-produced plasma. Under investigation is plasmas generated by action on solid-state target by radiation from picosecond terawatt Nd-glass laser having intensity of 10 to the power 16 10 to the power 18 Watt per centimeter squared. Peculiarities of such plasmas have called for modernization of conventional methods and detectors for measurement of neutron and gamma-radiation. Diagnostic methods imply use of scintillation counters based on stilbene crystal, scintillation gamma-spectrometer based on NaI(Tl) crystal and proportional counters based on He III. The paper as well presents results of the experimental investigation on generation of gamma-quanta and neutrons in laser-produced plasma. The experimental methods and detectors described in the paper provide a basis for studies on a wide spectrum of atomic and nuclear processes going in the laser-produced dense plasmas. The present work was supported by International Science and Technology Center under Project number 856.

Matafonov, Anatoly

2000-03-01

288

X- and gamma-ray N+PP+ silicon detectors with high radiation resistance  

NASA Astrophysics Data System (ADS)

The paper describes some results concerning technology and behavior of x and gamma-ray N(superscript +)PP(superscript +) silicon detectors used in physics research, industrial and medical radiography and non-destructive testing. These detectors work at the room-temperature and can be used individually to detect x- and soft gamma-rays, or coupled with scintillators for higher incoming energies. Electrical characteristics of these photodiodes, their modification after exposure to radiation and results of spectroscopic x- and gamma-ray measurements are discussed. Devices manufactured under this technology proved to be stable after an exposure in high intensity gamma field with the dose range of 10 krad - 5 Mrad. Nuclear radiation resistance was studied by irradiation with (superscript 60)Co gamma source (1.17, 1.33 MeV) at dose rates of 59 krad/hour and 570 krad/hour. Results indicate that proposed structures enable the development of reliable silicon detectors to be used in high gamma-radiation environments encountered in a lot of applications.

Cimpoca, Valerica; Petris, Mariana; Ruscu, Radu; Breten, Madalina; Moraru, Rodica

1997-07-01

289

XNAP: a hybrid pixel detector with nanosecond resolution for time resolved synchrotron radiation studies  

NASA Astrophysics Data System (ADS)

The XNAP collaboration is constructing a hybrid pixel X-ray detector based on a monolithic silicon avalanche photodiode (APD) sensor array aiming at applications in synchrotron radiation facilities. The 2D detector is capable of identifying which individual electron bunch produces each detected X-ray photon, even when the storage ring operates in multibunch filling modes. This instrument is intended to be used in X-ray Photon Correlation Spectroscopy and Nuclear Resonance experiments and serve as a demonstrator for various kind of time resolved diffraction and scattering applications as well as a very high count rate device. The detector is a 1 kilopixel device with 280 ?m pitch that implements both counting mode up to MHz frame rates and event-by-event readout with sub-nanosecond time resolution. The paper describes the detector design and some results obtained with small 4×4 pixel prototypes that have been built and measured to make and validate the most critical choices for the final detector.

Fajardo, P.; Baron, A. Q. R.; Dautet, H.; Davies, M.; Fischer, P.; Göttlicher, P.; Graafsma, H.; Hervé, C.; Rüffer, R.; Thil, C.

2013-03-01

290

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

291

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

292

Experimental evaluation of radiation susceptibility of high-speed CCD detectors for free-space optical communications application  

Microsoft Academic Search

Application of very fast CCD detectors to both fine pointing and tracking and to low data rate reception for free space optical communications has been demonstrated in several prior programs. CCD detector based wide field multi-channel receivers have been considered for several new applications. We are conducting a program whose goal is evaluation of radiation induced degradation in the properties

Theodore L. Miller; Dennis A. Thompson; Donald J. Nicholson

1993-01-01

293

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

SciTech Connect

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

Li Z.

2011-05-11

294

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

295

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

296

Radiation background in a LaBr3(Ce) gamma-ray scintillation detector.  

PubMed

Gamma-ray spectral analyses with a 5-cm × 5-cm LaBr3(Ce) detector and a NaI(Tl) detector of the same size show that the LaBr3(Ce) has much better gamma-ray peak resolution and full-energy peak counting efficiency but worse detection sensitivity. The LaBr3(Ce) detector has relatively high intrinsic radiation background due to the naturally occurring La radioisotope in lanthanum. Although this La background is entirely below the energy of 1,500 keV, additional background is in the energy region between 1,500 keV and 2,750 keV. The manufacturer attributes this radiation to alpha particles emitted by the five short-lived progeny of an Ac impurity. Comparative values for peak resolution, full-energy peak counting efficiency, and detection sensitivity are reported for Am, Co, and Cs. Results of counting Cs sources at two activity levels demonstrate the impact of background on detection sensitivity. PMID:22048488

Rosson, Robert; Lahr, Jeffrey; Kahn, Bernd

2011-12-01

297

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

298

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 (0.5MeV/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

299

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

300

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

NASA Astrophysics Data System (ADS)

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

Urbar, Jaroslav; Scheirich, Jan; Jakubek, Jan

2010-05-01

301

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

NASA Astrophysics Data System (ADS)

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

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

2004-09-01

302

Effects of radiation-induced defects on the charge collection efficiency of a silicon carbide particle detector  

NASA Astrophysics Data System (ADS)

Radiation hardness of 6H silicon carbide (SiC) p+n diode particle detectors has been studied. The charge collection efficiency (CCE) of the detectors decreases with the increased fluence of electrons with energies of 0.2 MeV and higher. Defect X2 with an activation energy of 0.5 eV was found in all detectors which showed the decreased CCE. The decreased CCE was restored to the initial value by thermal annealing of defect X2. It is concluded that defect X2 is responsible for the decreased CCE of 6H-SiC p+n diode particle detectors.

Iwamoto, Naoya; Onoda, Shinobu; Makino, Takahiro; Ohshima, Takeshi; Kojima, Kazutoshi; Nozaki, Shinji

2013-05-01

303

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

NASA Astrophysics Data System (ADS)

A low-cost direct solar radiation detector (DSRD) has been designed, characterized and calibrated. The detector was made of a simple silicon diode and then characterized with respect to spectral response, polar response and environmental stability. It was calibrated by using an Eppley normal incidence pyrheliometer (NIP) mounted on an Eppley power driven sun tracker (ST) whose axis is parallel to the Earth's axis of rotation. The DSRD and the NIP were mounted together on the ST. The results indicate that the DSRD follows the NIP very closely and can therefore be used in its place. The correlation between the DSRD and the NIP data is good with a correlation factor close to unity and a root mean square value close to zero.

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

2007-11-01

304

Fast bolometric response by high Tc detectors measured with subnanosecond synchrotron radiation  

NASA Astrophysics Data System (ADS)

A fast response by thin-film YBa2Cu3O(7-delta) detectors to pulsed, broadband, infrared radiation was measured. Synchrotron light from an electron storage ring was used as the infrared source, providing subnanosecond pulses from far infrared through visible. Pulse responsivities as high as 10 to the 6th V/J and as fast as 4 ns have been observed. For film thicknesses in the range 400-3200 A, the detector response follows the film absorptivity, while the speed varies inversely with thickness, suggesting a bolometric mechanism. Calculations based on such a model are in accord with the data. No evidence was found for any nonbolometric components in the response.

Carr, G. L.; Quijada, M.; Tanner, D. B.; Hirschmugl, C. J.; Williams, G. P.

1990-12-01

305

Characterization and TCAD modelling of termination structures for silicon radiation detectors  

NASA Astrophysics Data System (ADS)

We have recently proposed a novel junction termination structure for silicon radiation detectors, featuring all-p-type multiguard and scribe-line implants, with metal field-plates completely covering the gap between the implanted rings. The structure is intended for detector long-term stability enhancement even in adverse ambient conditions and for fabrication-process simplification. A thorough static characterization, including stability measurements in varying humidity conditions, has been carried out on a variety of samples fabricated at ITC-irst. Comparisons with diodes featuring an n-type implant along the border-or no edge structure at all-have been performed. The new structures show stable behaviour at relatively high bias (~200V), also in the presence of wide humidity changes (1-90%). A good qualitative agreement has been obtained between experimental results and simulation predictions, allowing to gain deep insight into the physical behaviour of the device.

Dittongo, S.; Boscardin, M.; Bosisio, L.; Ciacchi, M.; dalla Betta, G.-F.; Gregori, P.; Piemonte, C.; Rachevskaia, I.; Ronchin, S.; Zorzi, N.

2004-02-01

306

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

SciTech Connect

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

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

1999-08-23

307

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

Microsoft Academic Search

In radiation oncology applications, the need for higher-quality images has been driven by recent advances in radiation delivery systems that require online imaging. The existing electronic imaging devices commonly used to acquire portal images implement amorphous silicon (a-Si) detector, which exhibits poor image quality. Efforts for improvement have mostly been in the areas of noise and scatter reduction through software.

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

2008-01-01

308

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

NASA Astrophysics Data System (ADS)

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

Abbene, L.; Gerardi, G.

2011-10-01

309

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

NASA Astrophysics Data System (ADS)

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

Taylor, Edward W.

2006-09-01

310

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

NASA Astrophysics Data System (ADS)

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

Jing, T.

1995-05-01

311

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

SciTech Connect

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

Danny Dotson; John Mammosser

2005-05-01

312

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

ScienceCinema

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

313

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)

2010-08-18

314

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

SciTech Connect

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

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

2007-07-01

315

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

316

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

SciTech Connect

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

Brown, Gordon

2003-01-21

317

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

2011-12-30

318

State of the art of wide-bandgap semiconductor nuclear radiation detectors  

Microsoft Academic Search

Summary  The leading materials which operate as room temperature nuclear radiation detectors are HgI2, CdTe, and Cd1?x\\u000a Zn\\u000a x\\u000a Te (0.05>x>0.25). However, additional materials have also been developed, such as semi-insulating GaAs and PbI2. A comparison of the charge transport properties of all these materials will be made, followed by a discussion of each of\\u000a the materials separately. Crystal growth methods

M. Schieber; R. B. James; J. C. Lund; D. S. McGregor; T. S. Gilbert; J. M. Van Scyoc; R. W. Olsen; A. E. Pontau; T. S. Schlesinger; J. Toney

1996-01-01

319

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

SciTech Connect

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

Bolotnikov,A.

2009-06-02

320

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

321

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

SciTech Connect

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

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

2006-09-25

322

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

NASA Astrophysics Data System (ADS)

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

Alfaro, R.; Cruz, E.; Martinez, M. I.; Montaño, L. M.; Paic, G.; Sandoval, A.

2006-09-01

323

A radiotelemetry pill for the measurement of ionising radiation using a mercuric iodide detector.  

PubMed

A small radiation measuring pill is briefly described which utilises the principles of radiotelemetry and the properties of a room temperature semiconductor radiation detector such as mercuric iodide. By transmitting a radio signal to a remote receiver the pill could be an effective tool in localising bleeding sites along the gastrointestinal tract and also possibly in the diagnosis of gastrointestinal carcinoma. Other uses of the radiopill are suggested. The size of the pill is 27 mm x 10 mm diameter and consists of a mercuric iodide crystal, an amplifier, a frequency modulated transmitter and one battery. The radiotransmitter operates at about 106 MHz and has a range of about 10m, and the sensitivity of the pill has been found for 99Tcm, 131I and 32P. PMID:306112

Hassan, M A; Pearce, G; Edwards, J P

1978-03-01

324

Photoemission analysis of chemically modified TlBr surfaces for improved radiation detectors  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

325

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

326

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

NASA Astrophysics Data System (ADS)

In order to image the radiation field, instruments measure the position of interaction of the incident quanta, a task typically accomplished by partitioning the detector or its readout. We previously performed a fundamental investigation of the electrode design and pulse shape analysis routines required to optimize the detector's position resolution, when limited by both temporal and carrier uncertainties. If the transmission-line electrode structure is balanced at the frequencies of interest, then the time difference between the pulses at the readout end of a serpentine delay-line electrode structure can be used to measure the position at which the charge was collected. In this paper, we describe the fabrication techniques used to overcome the two greatest limitations of the early detectors, namely, high leakage currents and high propagation losses. In the following, we describe, through both models and measurements, the means by which: (a) one can achieve impedance matching by conversion of the electrode into a 50 ? asymmetric strip line and (b) one can minimize the propagation losses by the use of thick high-conductivity electrodes and the use of low-loss dielectrics (BaSrTiO3 and BaTiO3), as a part of an asymmetric strip line design. In order to accomplish low leakage designs, we describe the fabrication of delay-line PIN devices with metal field plates (MFPs) and multiple floating guard rings.

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

2011-10-01

327

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

NASA Astrophysics Data System (ADS)

Bismuth tri-iodide is a wide band-gap semiconductor material that may be able to operate as a radiation detector without any cooling mechanism. This material has a higher effective atomic number than germanium and CdZnTe, and thus should have a higher gamma-ray detection efficiency, particularly for moderate and high energy gamma-rays. Unfortunately, not much is known about bismuth tri-iodide, and the general properties of the material need to be investigated. Bismuth tri-iodide does not suffer from some of the material issues, such as a solid state phase transition and dissociation in air, that mercuric iodide (another high-Z, wide band-gap semiconductor) does. Thus, bismuth tri-iodide is both easier to grow and handle than mercuric iodide. A modified vertical Bridgman growth technique is being used to grow large, single bismuth tri-iodide crystals. Zone refining is being performed to purify the starting material and increase the resistivity of the crystals. The single crystals being grown are typically several hundred mm3. The larger crystals grown are approximately 2 cm3. Initial detectors are being fabricated using both gold and palladium electrodes and palladium wire. The electron mobility measured using an alpha source was determined to be 260±50 cm2/Vs. An alpha spectrum was recorded with one of the devices; however the detector appears to suffer from polarization.

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

2011-10-01

328

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

NASA Astrophysics Data System (ADS)

Hybrid semiconductor pixel detectors are being investigated as imaging devices for radiography and synchrotron radiation beam applications. Based on previous work in the CERN RD19 and the UK IMPACT collaborations, a photon counting GaAs pixel detector (PCD) has been used in an X-ray powder diffraction experiment. The device consists of a 200?m thick SI-LEC GaAs detector patterned in a 64×64 array of 170?m pitch square pixels, bump-bonded to readout electronics operating in single photon counting mode. Intensity peaks in the powder diffraction pattern of KNbO3 have been resolved and compared with results using the standard scintillator, and a PCD predecessor (the ?3). The PCD shows improved speed, dynamic range, 2-D information and comparable spatial resolution to the standard scintillator based systems. It also overcomes the severe dead time limitations of the ?3 by using a shutter based acquisition mode. A brief demonstration of the possibilities of the system for dental radiography and image processing are given, showing a marked reduction in patient dose and dead time compared with film.

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

2001-03-01

329

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

330

Gravitation waves. Proceedings of the conference on design of gravitational wave radiator and detector  

NASA Astrophysics Data System (ADS)

Separate abstracts were prepared of 20 papers presented at this conference on gravity wave radiation and detection. Among the topics discussed were the following: experiment design for the radiation and detection of gravity waves in the laboratory; development of a vibrational base for the Gravity apparatus; designing the substructure for the gravity wave device; parametric transformation of the weak gravity wave into the electromagnetic in the three-level system; gravity wave detection with the aid of resonance multiwave parametric processes; the influence of the structure of the impulse of coherent radiation on the stability of the anticipated gravity waves from monocrystals; the possibility of the detection of high frequency gravity radiation via laser interferometry; some examples of noise in laser interferometry gravity wave antennas; the optical resonator in the gravity wave field; the gravity wave detector on the basis of light diffraction; the detection of slight variations in Earth's gravitational field with the aid of optical laser interferometry; and the writing of a dictionary of gravity related terms.

331

Simulating charged-particle tracks in radiation detectors by means of x-ray and laser beams (review)  

Microsoft Academic Search

This review deals with methods of simulating charged-particle tracks in track and coordinate-sensitive detectors by the use of collimated electromagnetic radiation in the x-ray and near-UV ranges. Existing results are surveyed together with the prospects for the method. Specific areas reviewed include: the track of a fast charged particle in a gas-filled detector; track simulation with x-rays in a drift

E. M. Gushchin; A. N. Lebedev; S. V. Somov

1985-01-01

332

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

SciTech Connect

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

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

2012-04-15

333

Complete suppression of reverse annealing of neutron radiation damage during active gamma irradiation in MCZ Si detectors  

NASA Astrophysics Data System (ADS)

For the development of radiation-hard Si detectors for the SiD BeamCal (Si Detector Beam Calorimeter) program for International Linear Collider (ILC), n-type Magnetic Czochralski Si detectors have been irradiated first by fast neutrons to fluences of 1.5×1014 and 3×1014 neq/cm2, and then by gamma up to 500 Mrad. The motivation of this mixed radiation project is to test the radiation hardness of MCZ detectors that may utilize the gamma/electron radiation to compensate the negative effects caused by neutron irradiation, all of which exists in the ILC radiation environment. By using the positive space charge created by gamma radiation in MCZ Si detectors, one can cancel the negative space charge created by neutrons, thus reducing the overall net space charge density and therefore the full depletion voltage of the detector. It has been found that gamma radiation has suppressed the room temperature reverse annealing in neutron-irradiated detectors during the 5.5 month of time needed to reach a radiation dose of 500 Mrad. The room temperature annealing (RTA) was verified in control samples (irradiated to the same neutron fluences, but going through this 5.5 month RTA without gamma radiation). This suppression is in agreement with our previous predictions, since negative space charge generated during the reverse annealing was suppressed by positive space charge induced by gamma radiation. The effect is that regardless of the received neutron fluence the reverse annealing is totally suppressed by the same dose of gamma rays (500 Mrad). It has been found that the full depletion voltage for the two detectors irradiated to two different neutron fluences stays the same before and after gamma radiation. Meanwhile, for the control samples also irradiated to two different neutron fluences, full depletion voltages have gone up during this period. The increase in full depletion voltage in the control samples corresponds to the generation of negative space charge, and this increase in concentration of negative space charge goes up with the neutron fluence. If we assume the reverse annealing is also taking place for the two gamma-irradiated samples with similarly different concentrations of negative space charge generated, the observed effect of no changes in space charge (no changes in Vfd) in these two gamma-irradiated samples would imply that concentrations of positive space charge created in these two control samples are different at the same gamma dose, and gamma irradiation effectively "switched off", the RT (room temperature) reverse annealing of neutron irradiation. It has also been found that as soon as the gamma irradiation stops, the RT reverse annealing of neutron irradiation-induced defects resumes with same rate as that of the control detectors. This behavior in mixed radiation samples (neutron plus gamma) would suggest some nonlinear effect (defects induced by mixed-radiations are not additive of those by individual radiation alone), or interaction of radiation induced acceptor-type and donor-type defects.

Li, Z.; Verbitskaya, E.; Chen, W.; Eremin, V.; Gul, R.; Härkönen, J.; Hoeferkamp, M.; Kierstead, J.; Metcalfe, J.; Seidel, S.

2013-01-01

334

A low-power, radiation-resistant, Silicon-Drift-Detector array for extraterrestrial element mapping  

NASA Astrophysics Data System (ADS)

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

2012-02-01

335

Counterbalanced radiation detection system  

SciTech Connect

A counterbalanced radiation detection system is described comprising: (a) a stand; (b) a first radiation detector; (c) a first radiation detector arm means for tiltably connecting the first radiation detector with the stand; (d) a second radiation detector; (e) a second radiation detector arm means for tiltably connecting the second radiation detector with the stand, whereby the tilting angles of the radiation detector arm means define a distance between the radiation detectors; and (f) a torque transforming means connected between the first and second radiation detector arm means for transforming the torque created by one of the radiation detectors in a sense opposed to the torque created by the other radiation detector.

Platz, W.

1987-03-24

336

High Spatial Resolution Radiation Detectors Based on Hydrogenated Amorphous Silicon and Scintillator  

NASA Astrophysics Data System (ADS)

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

Jing, Tao

1995-01-01

337

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

338

A low noise FET with integrated charge restoration for radiation detectors  

SciTech Connect

A novel pulsed, non-optical, reset technique for use in charge sensitive amplifiers and radiation detectors is described. The first stage FET and charge restoration are integrated into one 5-terminal device labelled the Pentafet. A pulse of minority carriers is injected directly into the channel of the FET. The technique is fast and there are no after effects on the operation of the FET. Very low noise performance is achieved even at high count rates. The high energy rate product capability of the device is demonstrated by analyzing Mn x-rays in the presence of high energy electrons from an Sr 90 beta source and in a transmission electron microscope (TEM).

Nashoishibi, T.; White, G. (Link Analytical Ltd., Halifax Road, High Wyucombe, Bucks, HP 123SE (GB))

1990-04-01

339

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

DOEpatents

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

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

2000-01-01

340

Vertical Bridgman growth of Cd1-x ZnxTe for room temperature radiation detectors  

NASA Astrophysics Data System (ADS)

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

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

2007-09-01

341

Growth and characterization of CdTeSe for room-temperature radiation detector applications  

NASA Astrophysics Data System (ADS)

The near-unity segregation coefficient of Se in a CdTe matrix ensures the compositional homogeneity, both axial- and radial, of the CdTeSe ternary compound, so making it a material of choice for room- temperature radiation detectors. In this study, we grew CdTeSe crystals by the Traveling Heater Method (THM), using Te as the solvent, and characterized the crystals by IR transmission microscopy, white-beam X-ray diffraction topography, and low-temperature photoluminescence. The total average concentration of the secondary phases obtained for the CdTeSe sample was about 7x104 cm-3 for crystals grown at two different laboratories. The best resistivity registered was 5x109 ohm-cm, and the estimated ?? product for the electrons was 3-4x10-3 cm2/V.

Roy, U. N.; Bolotnikov, A. E.; Camarda, G. S.; Cui, Y.; Hossain, A.; Yang, G.; James, R. B.; Fauler, A.; Fiederle, M.; Sowinska, M.; Hennard, G.; Siffert, P.

2013-09-01

342

Evaluation of detector material and radiation source position on Compton camera's ability for multitracer imaging.  

PubMed

We present a study on the effects of detector material, radionuclide source and source position on the Compton camera aimed at realistic characterization of the camera's performance in multitracer imaging as it relates to brain imaging. The GEANT4 Monte Carlo simulation software was used to model the physics of radiation transport and interactions with matter. Silicon (Si) and germanium (Ge) detectors were evaluated for the scatterer, and cadmium zinc telluride (CZT) and cerium-doped lanthanum bromide (LaBr(3):Ce) were considered for the absorber. Image quality analyses suggest that the use of Si as the scatterer and CZT as the absorber would be preferred. Nevertheless, two simulated Compton camera models (Si/CZT and Si/LaBr(3):Ce Compton cameras) that are considered in this study demonstrated good capabilities for multitracer imaging in that four radiotracers within the nuclear medicine energy range are clearly visualized by the cameras. It is found however that beyond a range difference of about 2 cm for (113m)In and (18)F radiotracers in a brain phantom, there may be a need to rotate the Compton camera for efficient brain imaging. PMID:22829298

Uche, C Z; Round, W H; Cree, M J

2012-07-25

343

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

SciTech Connect

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

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

1985-12-01

344

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

345

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

NASA Astrophysics Data System (ADS)

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

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

2010-11-01

346

Fluctuations in induced charge introduced by Te inclusions within CdZnTe radiation detectors  

SciTech Connect

Recently, homogenization theory based on a multiple-scale perturbation of the electron transport equation has been used to derive a mathematical framework for modeling the excess charge lost to Te inclusions within radiation detectors based on semi-insulating cadmium zinc telluride (CdZnTe). In that theory, the heterogeneous material is mathematically replaced by a homogenized CdZnTe crystal whose effective electron attenuation length incorporates the additional uniform electron trapping caused by the inclusions. In this paper, the homogenization theory is extended to incorporate fluctuations in the induced charge (i.e., charge collection nonuniformities) introduced by the random position and size distributions of a noncorrelated population of small (i.e, <20 {mu}m) Te inclusions. Analysis of the effective parameters derived within the homogenized framework is used to develop a probability distribution of effective electron attenuation lengths, and therefore effective mobility-lifetime products, as a function of both the position and size distribution of Te inclusions. Example distributions are detailed for the case of an exponential size distribution at various number densities. Further, it is demonstrated that the inclusion-induced material nonuniformities derived in this paper can be numerically sampled efficiently, making them applicable to Monte Carlo device simulation of realistic CdZnTe detectors. Simulated charge induction maps and pulse-height spectra are presented and compared to recently published measurements.

Bale, Derek S. [Endicott Interconnect Detection and Imaging Systems, 373 Saxonburg Boulevard, Saxonburg, Pennsylvania 16056 (United States)

2010-07-15

347

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

NASA Astrophysics Data System (ADS)

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

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

2007-06-01

348

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

NASA Astrophysics Data System (ADS)

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

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

2003-06-01

349

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

350

Operation characteristics of ionizing radiation detectors based on inorganic and plastic scintillators for nuclear physics and medical instrumentation  

Microsoft Academic Search

Main operation characteristics of radiation detectors, using various scintillation substances, are calculated on the base of a realistic optical model of a scintillator. The calculation method takes account of a mirror-type maximum of the diffuse reflection indicatrix which is important for light collection in a scintillator. The comparison is carried out between various cases differing in the scintillator geometry, the

M. Globus; B. Grinyov

1995-01-01

351

Operation characteristics of ionizing radiation detectors based on inorganic and plastic scintillators for nuclear physics and medical instrumentation  

Microsoft Academic Search

Main operation characteristics of radiation detectors, using various scintillation substances, are calculated on the base of a realistic optical model of a scintillator. The calculation method takes account of a mirror-type maximum of the diffuse reflection indicatrix which is important for light collection in a scintillator. The comparison is carried out between various cases. Differing in the scintillator geometry, the

M. Globus; B. Grinyov

1996-01-01

352

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

353

Detector for Gamma-Radiation-Imaging Devices: Cooled bismuth germanate crystal has good scintillation and mechanical properties.  

National Technical Information Service (NTIS)

This citation summarizes a one-page announcement of technology available for utilization. A cooled bismuth germanate crystal is an effective gamma-radiation detector for scintillation cameras. This material, Bi4Ge3O12 (referred to as BGO), is denser and h...

1981-01-01

354

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

355

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

NASA Astrophysics Data System (ADS)

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

Yoon, Hojun

356

Monte Carlo calculation of the energy response characteristics of a RadFET radiation detector  

NASA Astrophysics Data System (ADS)

The Metal -Oxide Semiconductor Field-Effect-Transistor (MOSFET, RadFET) is frequently used as a sensor of ionizing radiation in nuclear-medicine, diagnostic-radiology, radiotherapy quality-assurance and in the nuclear and space industries. We focused our investigations on calculating the energy response of a p-type RadFET to low-energy photons in range from 12 keV to 2 MeV and on understanding the influence of uncertainties in the composition and geometry of the device in calculating the energy response function. All results were normalized to unit air kerma incident on the RadFET for incident photon energy of 1.1 MeV. The calculations of the energy response characteristics of a RadFET radiation detector were performed via Monte Carlo simulations using the MCNPX code and for a limited number of incident photon energies the FOTELP code was also used for the sake of comparison. The geometry of the RadFET was modeled as a simple stack of appropriate materials. Our goal was to obtain results with statistical uncertainties better than 1% (fulfilled in MCNPX calculations for all incident energies which resulted in simulations with 1 - 2×109 histories.

Belicev, P.; Spasic Jokic, V.; Mayer, S.; Milosevic, M.; Ilic, R.; Pesic, M.

2010-07-01

357

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

358

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

359

Transmutation detectors  

NASA Astrophysics Data System (ADS)

We have designed a new type of detectors, called transmutation detectors, which can be used primarily for neutron fluence measurement. The transmutation detector method differs from the commonly used activation detector method in evaluation of detector response after irradiation. Instead of radionuclide activity measurement using radiometric methods, the concentration of stable non-gaseous nuclides generated by transmutation in the detector is measured using analytical methods like mass spectrometry. Prospective elements and nuclear reactions for transmutation detectors are listed and initial experimental results are given. The transmutation detector method could be used primarily for long-term measurement of neutron fluence in fission nuclear reactors, but in principle it could be used for any type of radiation that can cause transmutation of nuclides in detectors. This method could also be used for measurement in accelerators or fusion reactors.

Viererbl, L.; Lahodová, Z.; Klupák, V.; Sus, F.; Ku?era, J.; K?s, P.; Marek, M.

2011-03-01

360

Study of surface recombination velocity of Cd1-xZnxTe radiation detectors by direct current photoconductivity  

NASA Astrophysics Data System (ADS)

The surface recombination velocity of a Cd1-xZnxTe (CZT) radiation detector treated by mechanical polishing and by a standard 5% bromine in methanol chemical etch is reported. The light power dependence of the surface recombination velocity was measured using dc photoconductivity. The results reveal that the surface recombination velocity is a function of the electron generation rate, which can be described by a Shockley-Read one-center model. It was observed that the surface recombination velocity of the CZT detector treated by polishing only is much larger than that treated with polishing followed by chemical etching. The correlation of dc photoconductivity and low-temperature photoluminescence measurements of the CZT detector is also discussed.

Cui, Y.; Groza, M.; Hillman, D.; Burger, A.; James, R. B.

2002-09-01

361

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

NASA Astrophysics Data System (ADS)

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

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

1997-02-01

362

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

2013-07-22

363

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

SciTech Connect

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

364

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

365

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

366

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

SciTech Connect

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

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

2006-03-01

367

International comparison of radiation-temperature measurements with filtered detectors over the temperature range 1380 K to 3100 K  

Microsoft Academic Search

A series of black-body radiation-temperature measurements has been made over the temperature range 1380 K to 3100 K using two different designs of pyrolytic-graphite black bodies with calculated emissivities of 0.999. All measurements were performed at the All-Russian Research Institute for Optophysical Measurements (VNIIOFI) during June 1997. A filter photometer from the VNIIOFI, broadband glass-filter detectors from the Physikalisch-Technische Bundesanstalt

N. J. Harrison; N. P. Fox; P. Sperfeld; J. Metzdorf; B. B. Khlevnoy; R. I. Stolyarevskaya; V. B. Khromchenko; S. N. Mekhontsev; V. I. Shapoval; M. F. Zelener; V. I. Sapritsky

1998-01-01

368

An improved termination structure for silicon radiation detectors with all-P-type multiguard and cutline implants  

Microsoft Academic Search

A junction termination structure for silicon radiation detectors is investigated, featuring all-p-type multiguard and scribe-line implants, with metal field-plates providing complete coverage of the oxide upper surface above nonimplanted regions. The sensitive interface between oxide and n-type substrate is thus electrostatically screened from the external environment, resulting in improved long-term stability of the device and excellent insensitivity to ambient conditions

Maurizio Boscardin; Luciano Bosisio; Andrea Candelori; G. F. Dalla Betta; S. Dittongo; P. Gregori; C. Piemonte; I. Rachevskaia; S. Ronchin; N. Zorzi

2003-01-01

369

Stratospheric Radiation Environment measurements, calibrations and pattern recognition by CERN MEDIPIX-2 and TIMEPIX Radiation Imaging Detectors on ESA BEXUS campaigns  

NASA Astrophysics Data System (ADS)

Results of the first two experiments using a MEDIPIX-2 and TIMEPIX detector for cosmic ray imaging in stratospheric environment are presented. The detecting device was based on hybrid pixel detector of MEDIPIX-2/TIMEPIX developed at CERN with USB interface developed at Institute of Experimental and Applied Physics of Czech Technical University in Prague. The detector was used in its tracking mode allowing it to operate as an ''active nuclear emulsion'' The actual flight time of BEXUS7 on 8th October 2008 was over 4 hours, with 2 hours at stable floating altitude of 26km. The flight opportunity was provided by Education dept. of European Space Agency (ESA) and Eurolaunch (Collaboration of SSC and DLR, German Space Agency). The motivation was to check proper calibration by detecting height-dependent profiles of ionizing radiation, also testing detector endurance and performance. BEXUS is quite ideal platform for such in-situ measurements. Not only because of the high altitudes reached, but also due to its slow ascent velocity for statistically relevant sampling of the ambient environment. Detector performance was evaluated for further design implications of advanced concept focusing on Cosmic Ray Induced Ionization rate measurements prepared for flight with additional instrumentation in October 2009 on BEXUS8. The preliminary results of the second campaign to be presented in scope of the outcomes of first campaign.

Urbar, J.; Jakubek, J.; Scheirich, J.

2009-12-01

370

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

PubMed

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

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

2013-02-08

371

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

NASA Astrophysics Data System (ADS)

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

Bale, Derek S.

2010-03-01

372

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

NASA Astrophysics Data System (ADS)

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

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

2011-01-01

373

Comparison of the spectrometric properties of two series of CdZnTe gamma radiation detectors  

NASA Astrophysics Data System (ADS)

Room-temperature semiconductor detectors are used in the field of nuclear safeguards. Gamma spectra obtained with hemispherical CdZnTe detectors present distortions due to incomplete charge collection. The full-energy peaks are asymmetric and they are characterized by a long low energy tailing. In the present work, the full-energy peak of 14 detectors CZT/500 (RITEC) and 8 CZT/60 (RITEC) was described with a set of four functions. The fit parameters were determined as a function of the energy for each detector and were applied to the calculation of the efficiency. The results show that, the fit parameter values are highly variable over the individual detectors of each type. It is not possible to associate a unique set of parameters to describe the full energy peak of a group of detectors. However, the use of individual parameter sets leads to a more precise evaluation of gamma spectra of fission products in nuclear spent fuel.

Berndt, Reinhard; Mortreau, Patricia; Braun, Alexander

2001-12-01

374

Position sensitive detectors for synchrotron radiation studies: the tortoise and the hare?  

NASA Astrophysics Data System (ADS)

The huge gulf between the high photon fluxes available from synchrotrons and the capabilities of detectors to measure the resulting photon, electron or ion signals is well known. Whilst accelerator technology continues to advance at a rapid pace, it is detector performance which represents the limiting factor for many synchrotron experiments. In some cases there are still single channel counting detectors based on 40-year-old designs operational on synchrotron beamlines. The dream of many researchers is a detector which is able to simultaneously image and perform spectroscopy at the required data rates. A solution is the massive integration of parallel electronics into detectors on a pixel by pixel basis. These ideas have been in gestation for very many years awaiting sufficient funding, nevertheless, several prototypes are now at the testing stage. The current status of these and other detector developments targeted at synchrotron science are briefly reviewed.

Lewis, Rob

2003-11-01

375

Fine-scale spatial response of CdZnTe radiation detectors  

SciTech Connect

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

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

1998-11-07

376

Modeling the e!ect of light generation and light attenuation properties on the performance of phosphors used in medical imaging radiation detectors  

Microsoft Academic Search

A theoretical description of the e!ect of light generation and light attenuation properties on the imaging performance of phosphor materials used in radiation detectors of medical imaging systems is presented. The description is based on a theoretical model employing analytical expressions for the detector optical gain (DOG) (emitted optical quanta per incident X-ray), the modulation transfer function (MTF), and the

I. Kandarakis; D. Cavouras

377

Modeling the effect of light generation and light attenuation properties on the performance of phosphors used in medical imaging radiation detectors  

Microsoft Academic Search

A theoretical description of the effect of light generation and light attenuation properties on the imaging performance of phosphor materials used in radiation detectors of medical imaging systems is presented. The description is based on a theoretical model employing analytical expressions for the detector optical gain (DOG) (emitted optical quanta per incident X-ray), the modulation transfer function (MTF), and the

I. Kandarakis; D. Cavouras

2001-01-01

378

Tests of the radiation hardness of VLSI Integrated Circuits and Silicon Strip Detectors for the SSC (Superconducting Super Collider) under neutron, proton, and gamma irradiation  

Microsoft Academic Search

As part of a program to develop a silicon strip central tracking detector system for the Superconducting Super Collider (SSC) we are studying the effects of radiation damage in silicon detectors and their associated front-end readout electronics. We report on the results of neutron and proton irradiations at the Los Alamos National Laboratory (LANL) and γ-ray irradiations at UC Santa

H. J. Ziock; C. Milner; W. F. Sommer; N. Carteglia; J. DeWitt; D. Dorfan; B. Hubbard; J. Leslie; K. F. OShaughnessy; D. Pitzl; W. A. Rowe; H. F. W. Sadrozinski; A. Seiden; E. Spencer; J. A. Ellison; P. Ferguson; Giubellino

1990-01-01

379

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

380

Composite detector for mixed radiations based on CsI(Tl) and dispersions of small ZnSe(Te) crystals  

NASA Astrophysics Data System (ADS)

A new large area detector of high-energy X-ray and ?-radiation has been designed and studied. A composite material based on small-crystalline ZnSe(Te) was applied onto the wide surface of a light guide. An experimental specimen has been prepared, which showed ?-sensitivity C=5.5cm. The spectrograms of a 90Sr+90Y ?-source obtained with the specimen under study make it possible to evaluate the age of the source by the ratio of low- and high-energy regions of the spectrum. The combined detector (CD) comprises a single crystalline plate of ZnSe(Te) placed onto the output window of a scintillating transparent light guide made of CsI(Tl) in the shape of a truncated pyramid. The CsI(Tl) light guide is used to create an additional channel for detection of ?-radiation, as well as for protecting the photodiode from the penetrating radiation. It is shown that introduction of the light guide does not worsen the energy resolution characteristics of ZnSe(Te). Separate detection of ?- and ?-radiation has been achieved under simultaneous excitation by 239Pu (ZnSe(Te), R=6%) and 241Am (CsI(Tl), R=20%). The use of selective optical filters allows separation of the peaks of total absorption (p.t.a.) in the case of their superposition.

Ryzhikov, V.; Gal'Chinetskii, L.; Katrunov, K.; Lisetskaya, E.; Gavriluk, V.; Zelenskaya, O.; Starzhynskiy, N.; Chernikov, V.

2005-03-01

381

Preliminary Studies of Charge Carrier Transport in Mercuric Iodide Radiation Detectors  

Microsoft Academic Search

Mercuric iodide single crystals have been grown by static and dynamic sublimation methods. Characteristics of contacts and detector capacitance have been studied by photon excitation methods. Gamma and X-ray spectrometry has been carried out with completed detectors showing resolutions comparable to the best results published to date. A measurement of hole trapping length has been made from the spectral shapes

Jorge Llacer; Michael M. K. Watt; M. Schieber; R. Carlston; W. Schnepple

1974-01-01

382

Amorphous silicon/crystalline silicon heterojunctions for nuclear radiation detector applications  

SciTech Connect

Results on characterization of electrical properties of amorphous Si films for the 3 different growth methods (RF sputtering, PECVD [plasma enhanced], LPCVD [low pressure]) are reported. Performance of these a-Si films as heterojunctions on high resistivity p-type and n- type crystalline Si is examined by measuring the noise, leakage current, and the alpha particle response of 5mm dia detector structures. It is demonstrated that heterojunction detectors formed by RF sputtered films and PECVD films are comparable in performance with conventional surface barrier detectors. Results indicate that the a-Si/c-Si heterojunctions have the potential to greatly simplify detector fabrication. Directions for future avenues of nuclear particle detector development are indicated.

Walton, J.T.; Hong, W.S.; Luke, P.N.; Wang, N.W. [Lawrence Berkeley National Lab., CA (United States); Ziemba, F.P. [Quantrad Sensor, Inc., Santa Clara, CA (United States)

1996-10-01

383

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

NASA Astrophysics Data System (ADS)

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

Szabó, J.; Pálfalvi, J. K.

2012-12-01

384

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

NASA Astrophysics Data System (ADS)

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

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

385

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

386

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

387

Superconducting tunneling-junction detectors of X-ray radiation. Issues concerning the energy resolution  

SciTech Connect

The effect of the recombination-and edge-related losses of nonequilibrium quasiparticles on the energy resolution of superconducting tunneling detectors is studied. The dependence of the signal on the energy of X-ray photons is measured and the shape of instrument-related lines is studied for the Ti/Nb/Al/AlO{sub x}/Al/Nb/NbN detectors with the Ti/Nb passive electrode. Experimental data are analyzed using the diffusion-based model of tunneling detectors.

Andrianov, V. A. [Skobel'tsyn Research Institute of Nuclear Physics at the Moscow State University (Russian Federation)], E-mail: andrva22@mail.ru; Gor'kov, V. P. [Moscow State University, Department of Computational Mathematics and Cybernetics (Russian Federation)], E-mail: v-p-gorkov@yandex.ru; Koshelets, V. P., E-mail: valery@hitech.cplire.ru; Filippenko, L. V. [Russian Academy of Sciences, Institute of Radio Engineering and Electronics (Russian Federation)

2007-02-15

388

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

389

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

390

An investigation into the radiation damage of the silicon detectors of the H1-PLUG calorimeter within the HERA environment  

NASA Astrophysics Data System (ADS)

The silicon detectors used in the H1-PLUG calorimeter have shown increasing aging effects during the '94 run period of the electron proton storage ring HERA. These effects were particularly manifest as degradation of the signal to noise level and the calibration stability. The reasons for this behaviour have been found to be correlated with radiation damage to the silicon oxide passivation edges of the detectors in strong and fluctuating increases of the leakage currents and in severe changes of the flat band voltages. Depletion voltages however are found to be stable and therefore bulk damage of the silicon can be excluded. A comparison with measurements made by thermoluminescence dosimeters as well as related laboratory experiments suggest that the aging is due to very low energetic electrons and photons.

Fretwurst, E.; Hildesheim, W.; Lindstroem, G.; Seidel, M.

1996-02-01

391

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

NASA Astrophysics Data System (ADS)

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

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

2003-08-01

392

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

393

Potential distribution in voltage terminating structures with floating p-n junction rings of silicon radiation detectors  

SciTech Connect

A model of the potential distribution in voltage terminating structures (VTSs) with floating p{sup +}-n junction rings in silicon radiation detectors is proposed. The model is based on experimental current-voltage characteristic of interring gaps, measured for detectors based on high-resistivity silicon with resistivities from 1 to 25 k{Omega} cm. The physical basis of the model is the injection principle of current flow through VTS interring gaps, which becomes possible at a certain electric field distribution in space charge regions of p{sup +}-n junctions of the sensitive contact and rings. It is shown that the injection current flow is a universal operation principle of the VTS with floating rings, which leads to rigid stabilization of potentials of individual rings. As a result, it becomes possible to divide the potential irrespective of the semiconductor material resistivity.

Verbitskaya, E. V., E-mail: elena.verbitskaya@mail.ioife.ru; Eremin, V. K.; Safonova, N. N.; Eremin, I. V.; Tuboltsev, Yu. V. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Golubkov, S. A.; Konkov, K. A. [Yuzhnaya Promzona, Research Institute of Materials Science and Technology (Russian Federation)

2011-04-15

394

Light-output response of the plastic scintillator for the Mars Science Laboratory (MSL) Radiation Assessment Detector (RAD)  

NASA Astrophysics Data System (ADS)

The Radiation Assessment Detector (RAD) onboard NASA's Mars Science Laboratory (MSL) rover mission has been designed to detect a wide range of particle types (charged and neutral) and energies on the Mars surface. The BC432m plastic scintillator coupled to PIN photodiodes has been used as a neutron detector as well as an anticoincidence shield for the RAD instrument. We present an experimental study of the non-linear light-output response of the BC432m for protons and neutrons beams. The experimental results have been compared to the parametric formula based on the theoretical work of Birks and Chou. Furthermore, a comparison between the quenching effect found in the BC432m and in other inorganic scintillators (CsI:Tl) used in the RAD instrument has been performed.

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

2008-12-01

395

Fabrication of Radiation Detectors with HgI sub 2 Crystals Grown from a Solution.  

National Technical Information Service (NTIS)

Mercuric Iodide crystals grown from a solution of molecular complexes with dimethylsulfoxide have been evaluated as gamma -ray and X-ray room temperature detectors. Compared with materials grown from the vapor phase these crystals are characterized by a l...

A. Friant J. Mellet C. Saliou T. Mohammed Brahim

1979-01-01

396

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

SciTech Connect

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

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

2003-07-29

397

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

Microsoft Academic Search

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

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

2008-01-01

398

The THGEM: A thick robust gaseous electron multiplier for radiation detectors  

NASA Astrophysics Data System (ADS)

We briefly present the principal properties of THGEM detectors, in standard and in noble gases (Xe, Kr, Ar and Ne), and shortly discuss their potential applications in accelerator- and non-accelerator-based experiments. UV-photon imaging in RICH, tracking of ionizing particles, large-volume TPCs for rare-events, sampling elements in digital calorimetry, ionization and scintillation recording from noble-liquid detectors, X-ray and neutron radiography etc.

Breskin, A.; Cortesi, M.; Alon, R.; Miyamoto, J.; Peskov, V.; Bartesaghi, G.; Chechik, R.; Dangendorf, V.; Maia, J. M.; Dos Santos, J. M. F.

2010-11-01

399

LRAD, semiconductor, and other radiation detectors applied to environmental monitoring for alpha and beta contamination  

Microsoft Academic Search

The very short range of alpha particles in air (typically 2 to 3 cm) has severely limited the utility of traditional alpha monitors for detecting and identifying small amounts of alpha-producing contamination in soil, water, and other materials. Monitors based on the traditional alpha detector technology are often hard-pressed to meet continually increasing sensitivity requirements. The long-range alpha detector (LRAD)

D. W. MacArthur; K. E. Bower

1993-01-01

400

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

NASA Astrophysics Data System (ADS)

The performance of a nuclear radiation detector fabricated from Vertical Gradient Freeze (VGF) semi-insulating Fe-doped InP was investigated. Pulse height spectra were acquired when the detector was irradiated with alpha particles from 241Am, as a function of temperature and detector bias voltage. The spectroscopic performance of the detector was limited at room temperature due to the presence of a high leakage current. At a bias of -150V, a room temperature leakage current density of 2.4×10-6A/mm2 was observed which reduced to 7.1×10-8A/mm2 at a temperature of -21°C. By biasing the irradiated detector contact at either a negative or positive potential, the charge collection efficiency (CCE) was measured separately for pulses produced predominantly by electron transport and for pulses produced predominantly by hole transport, respectively. At -21°C a maximum CCE of 72% was obtained for the electron signal and 44% for the hole signal. As a function of bias the CCE of the electrons remained constant in the temperature range -21°C to +19°C, whilst that of the holes exhibited a significant variation. By comparison with the Hecht relationship estimates of the carrier mobility-lifetime /(??) products are deduced, which are similar for both holes and electrons and in the range 5×10-7-8×10-7cm2/V. A reduction in /?? is observed at lower temperature for holes, whereas the value for electrons remains constant over the temperature range studied.

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

2001-06-01

401

Comparison of a Detector-Based Near-IR Radiance Scale to an ITS90 Calibrated Radiation Thermometer  

Microsoft Academic Search

Integrating-sphere-input InGaAs radiometers (ISIR) have been developed at the National Institute of Standards and Technology\\u000a (NIST) to extend the detector-based calibration of radiation thermometers from the Si range to the near-infrared (NIR). These\\u000a near-infrared radiometers are used to determine the reference spectral irradiance responsivity scale based on the primary-standard\\u000a cryogenic radiometer. The irradiance responsivity scale is then propagated to spectral

G. P. Eppeldauer; H. W. Yoon; J. Zeng; T. C. Larason

402

A CsI(Na) based radiation detector for high resolution imaging studies using iodine 125 in small animal research  

SciTech Connect

The authors report on the development of a high resolution radiation imaging system which is capable of detecting and imaging the coincident gamma and X-ray emissions of the radioisotope iodine 125 ({sup 125}I). Iodine 125 is commonly available as a radioactive label to tag molecular biology probes. Iodine 125 decays via electron capture emitting a 35 keV gamma-ray with the prompt emission of several 27-32 keV X-rays. A coincidence condition can be set to detect the {sup 125}I decays thus reducing background radiation contribution to the image. They are testing the use of arrays of CsI(Na) crystal scintillators coupled to position sensitive photomultiplier tubes for this application. Laboratory studies have thus far been done on mice using a prototype of the detector which is intended to be used to image gene expression in live mice to advance research in neurobiology.

A. Weisenberger; E. Bradley; S. Majewski; and M. Saha

1997-05-01

403

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

404

Detective quantum efficiency of an amorphous selenium detector to megavoltage radiation.  

PubMed

The spatial frequency dependent detective quantum efficiency (DQE(f)) of a high-resolution selenium-based imaging system has been measured at megavoltage energies. These results have been compared with theoretical calculations. The imaging system was a video tube with a 5 microm amorphous selenium (a-Se) target which was irradiated by 1.25 MeV gamma-rays. The modulation transfer function (MTF) decreased rapidly with spatial frequency (determined by spread of electrons in the build-up material) while the noise power spectrum was constant as a function of spatial frequency. The DQE obtained from these MTF and noise power measurements was compared with a Monte Carlo model of the pulse height spectrum of the detector. The DQE(0) model accounted for the interaction of x rays with the detector as well as the energy-dependent gain (charge generated/energy deposition). Good agreement between the calculated and measured DQE(0) was found. The model was also used to estimate the DQE(f) of a metal plate + a-Se detector which was compared with a metal plate + phosphor system of the same mass thickness. The DQE(f) s of both detectors are very similar, indicating that the choice of which detector is better will be based upon criteria other than DQE(f), such as read-out approach, ease of manufacture or sensitivity. PMID:10368025

Mah, D; Rawlinson, J A; Rowlands, J A

1999-05-01

405

Transport of the charge carriers in SiC-detector structures after extreme radiation fluences  

NASA Astrophysics Data System (ADS)

The charge collection efficiency (CCE) of SiC-detectors preliminarily irradiated with 8 MeV protons at a fluence of 1014 cm-2 was investigated. Nuclear spectrometric techniques were employed, with 5.4 MeV alpha particles used to test the detectors. A concentration of primarily created defects of 4×1016 cm-3 was estimated and deep compensation of SiC conductivity was observed. In order to obtain a more uniform electric field distribution across the detectors, it is suggested to connect the structure in the forward direction. The experimental data obtained are processed using a simple model of signal formation. The model makes it possible to separate the contributions of the electrons and holes to the CCE.

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

2006-12-01

406

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

SciTech Connect

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

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

2010-08-15

407

Modelling spatial distribution of defects and estimation of electrical degradation of silicon detectors in radiation fields at high luminosity  

NASA Astrophysics Data System (ADS)

The irradiation represents a useful tool for determining the characteristics of defects in semiconductors as well as a method to evaluate their degradation, a fact with important technological consequences. In this contribution, starting from available data on the degradation of silicon detector characteristics in radiation fields, these effects are explained in the frame of a model that supposes also the production of the SiFFCD defect due to irradiation. The displacement threshold energies different for different crystallographic axes, considered as parameters of the model, are established and the results obtained could contribute to clarify these controversial aspects. Predictions of the degradation of electrical parameters (leakage current, effective carrier concentration and effective trapping probabilities for electrons and holes) of DOFZ silicon detectors in the hadron background of the LHC accelerator, supposing operation at -10 °C, are done. The non-uniformity of the rate of production of primary defects and of complexes, as a function of depth, for incident particles with low kinetic energy was obtained by simulations using some particular and very simplifying assumptions, suggesting the possible important contribution of the low-energy component of the background spectra to detector degradation.

Lazanu, S.; Lazanu, I.

2007-12-01

408

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

409

Electrical properties of radiation detector based on polycrystalline mercuric iodide (HgI2) thick film  

NASA Astrophysics Data System (ADS)

Potentially low cost and large area polycrystalline mercuric Iodide (HgI2) is one of the preferred materials for the fabrication of room temperature X-ray and gamma-ray detectors. In this paper, the technique of fabricating polycrystalline HgI2 detectors was studied and the energy resolution of 13.1% for 5.5 MeV 241Am ? particles at room temperature was obtained for the first time. The optimal choice of particle injecting from negative interface enhances the collection efficiency.

Shi, Weimin; Zheng, Yaoming; Guo, Yuying; Zhang, Yu; Xu, Huan; Wang, Linjun; Xia, Yiben

2008-03-01

410

Development of pixelated mercuric iodide radiation detectors for room temperature gamma-ray spectroscopy  

NASA Astrophysics Data System (ADS)

Mercuric iodide (HgI2) detectors were studied as potential gamma-ray spectrometers that can operate at room temperature or above without the need for cooling. Similar to other compound semiconductor materials, HgI 2 suffers from poor hole molibity and severe hole trapping. Thus, poor spectroscopic results will occur if this detector material used with conventional planar electrodes. The use of single polarity charge sensing, whereby the energy deposited by the gamma-ray is determined solely by electron movement and collection, was attempted by incorporating pixelated anodes. The results showed remarkable spectroscopic improvement over conventional electrodes, with less than 2% energy resolution from single pixels on a 1 cm thick detector using a 662 keV Cs-137 gamma-ray source. The conventional planar cathode showed no photopeak due to the lack of hole movement in HgI2. Since the cathode signal has a relatively linear dependence on the depth of interaction, both the anode pixel and cathode signals were used to measure the depth of interaction. This was then used to correct for electron trapping and variations of the induced charge with the depth of interaction. Depth correction further improved the resolution for single pixels to as low as 1.4% (˜9 keV) energy resolution. Nearly three-quarters of all pixels tested on 1 cm thick detectors had resolutions less than 2% after depth correction was performed. Pixelated HgI2 detectors were also used to study the charge transport properties of the material. While the measured hole transportation properties were similar to previously measured values, measured (mutau)e values were on the order of 10-3 cm2/V, about an order of magnitude better than previously measured values. This demonstrates that the material quality may have improved over the past several years. The pixelated HgI2 detectors showed very little polarization, and remained stable over several months of operation. Continued development of these detectors will allow them to compete with current CdZnTe detectors, possibly improving on detection efficiency due to the higher atomic number of HgI2.

Baciak, James E.

411

Photon shot noise limited detection of terahertz radiation using a quantum capacitance detector  

NASA Astrophysics Data System (ADS)

We observed a sweep rate dependence of the quantum capacitance in a single Cooper-Pair box used as the readout of a Quantum Capacitance Detector. A model was developed that fits the data over five orders of magnitude in sweep rate and optical signal power and provides a natural calibration of the absorbed power. We are thereby able to measure the noise equivalent power of the detector as a function of absorbed power. We find that it is shot-noise-limited in detecting 1.5 THz photons with absorbed power ranging from 1 × 10-22 W to 1 × 10-17 W.

Echternach, P. M.; Stone, K. J.; Bradford, C. M.; Day, P. K.; Wilson, D. W.; Megerian, K. G.; Llombart, N.; Bueno, J.

2013-07-01

412

Field ionization of alkali-metal Rydberg states formed by resonance absorption of sunlight: Application as an ultraviolet radiation detector  

SciTech Connect

In order to assess the long-term threat posed to plant and animal life by ozone depletion and the resulting increase of ultraviolet (UV) radiation, the United States Department of Agriculture has established a UV irradiance monitoring program, with emphasis on the UV-B wavelength region between 290 nm and 320 nanometers. However, there is serious concern over the long-term stability of conventional instruments used to measure the UV-B flux. We have recently demonstrated the feasibility of using resonance ionization to monitor specific wavelengths in the UV-B band. However, instead of using high-intensity lasers to detect a few atoms as is typically done in resonance ionization experiments, the UV-B monitor is based upon using a relatively high pressure (about 10{sup -5} Torr) of vapor-phase cesium, rubidium, and/or potassium to detect photons. Specific Rydberg states formed by resonant absorption of UV-B radiation in these vapors can be identified by their unique voltage threshold for ionization. Our initial work has established that there is a high correlation between the detected Rydberg state and the wavelength of the absorbed light, so that it should be possible to construct a UV-B detector with an internal, absolute wavelength calibration. The initial work will be discussed and the prospect for making a UV-B detector will be examined.

Whitaker, T.; Bekov, G. [Atom Sciences, Inc., 114 Ridgeway Center, Oak Ridge, TN, 37830 (United States)

1995-04-01

413

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

414

Development of Pattern Recognition Software for Tracks of Ionizing Radiation In Medipix2-Based (TimePix) Pixel Detector Devices  

NASA Astrophysics Data System (ADS)

The principal aim of our project is to develop an efficient pattern recognition tool for the automated identification and classification of tracks of ionizing radiation as measured by a TimePix version of the hybrid semiconductor Medipix2 pixel detector system. Such a software tool would have a number of applications including dosimeters to assess the risk of human exposure to radiation, and area monitors to characterize the general background radiation environment harmful to humans and electronic equipment. We are particularly interested in the development of the real-time analysis software needed to support an operational dosimeter that can assess the radiation environment during space missions. Our software development project makes use of data taken in beams of heavy ions at HIMAC (Heavy Ion Medical Accelerator Facility) in Chiba, Japan, including data from several different heavy ions with similar Linear Energy Transfers (LETs) for calibration purposes. We describe two modules of our pattern recognition tool: feature generation and classification. Our first module builds on a segmentation algorithm that identifies tracks from the pixel image assuming an approximately elliptical form that varies in size and degree of elongation based on multiple factors, including the particle species and angle of incidence. Determining the charge and energy of the particles creating each track is a particularly challenging task because different energy and charge incident particles can produce very similar patterns. Our classification module invokes different algorithms such as decision trees, support vector machines, and Bayesian classifiers.

Vilalta, R.; Kuchibhotla, S.; Valerio, R.; Pinsky, L.

2011-12-01

415

Development of high pressure-high vacuum-high conductance piston valve for gas-filled radiation detectors  

NASA Astrophysics Data System (ADS)

Gas-filled radiation detectors need gas filling at pressures that range from few cms of mercury to as high as 25kg/cm2 at room temperature. Before gas-filling these detectors require evacuation to a vacuum of the order of ~1 × 10-5 mbar. For these operations of evacuation and gas filling a system consisting of a vacuum pump with a high vacuum gauge, gas cylinder with a pressure gauge and a valve is used. The valve has to meet the three requirements of compatibility with high-pressure and high vacuum and high conductance. A piston valve suitable for the evacuation and gas filling of radiation detectors has been designed and fabricated to meet the above requirements. The stainless steel body (80mm×160mm overall dimensions) valve with a piston arrangement has a 1/2 inch inlet/outlet opening, neoprene/viton O-ring at piston face & diameter for sealing and a knob for opening and closing the valve. The piston movement mechanism is designed to have minimum wear of sealing O-rings. The valve has been hydrostatic pressure tested up to 75bars and has Helium leak rate of less than 9.6×10-9 m bar ltr/sec in vacuum mode and 2×10-7 mbar ltr/sec in pressure mode. As compared to a commercial diaphragm valve, which needed 3 hours to evacuate a 7 litre chamber to 2.5×10-5 mbar, the new valve achieved vacuum 7.4×10-6mbar in the same time under the same conditions.

Prasad, D. N.; Ayyappan, R.; Kamble, L. P.; Singh, J. P.; Muralikrishna, L. V.; Alex, M.; Balagi, V.; Mukhopadhyay, P. K.

2008-05-01

416

Tests of the radiation hardness of VLSI Integrated Circuits and Silicon Strip Detectors for the SSC (Superconducting Super Collider) under neutron, proton, and gamma irradiation  

SciTech Connect

As part of a program to develop a silicon strip central tracking detector system for the Superconducting Super Collider (SSC) we are studying the effects of radiation damage in silicon detectors and their associated front-end readout electronics. We report on the results of neutron and proton irradiations at the Los Alamos National Laboratory (LANL) and {gamma}-ray irradiations at UC Santa Cruz (UCSC). Individual components on single-sided AC-coupled silicon strip detectors and on test structures were tested. Circuits fabricated in a radiation hard CMOS process and individual transistors fabricated using dielectric isolation bipolar technology were also studied. Results indicate that a silicon strip tracking detector system should have a lifetime of at least one decade at the SSC. 17 refs., 17 figs.

Ziock, H.J.; Milner, C.; Sommer, W.F. (Los Alamos National Lab., NM (USA)); Carteglia, N.; DeWitt, J.; Dorfan, D.; Hubbard, B.; Leslie, J.; O'Shaughnessy, K.F.; Pitzl, D.; Rowe, W.A.; Sadrozinski, H.F.W.; Seiden, A.; Spencer, E. (California Univ., Santa Cruz, CA (USA). Inst. for Particle Physics); Ellison, J.A. (California Univ., Riverside, CA (USA)); Ferguson, P. (Missouri Univ., Rolla, MO (USA)); Giubellino

1990-01-01

417

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

NASA Astrophysics Data System (ADS)

We report of the radiation hardness measurements that were performed in the developing work of a particle detector on-board ESA's forthcoming BepiColombo spacecraft. Two different high-Z semiconductor compounds, cadmium telluride (CdTe) and mercuric iodide (HgI2), were irradiated with 22 MeV protons in four steps to attain the estimated total dose of 10p/cm for the mission time. The performance of the detectors was studied before and after every irradiation with radioactive 55Fe source Mn K? 5.9 keV emission line. We studied the impact of the proton beam exposure on detector leakage current, energy resolution and charge collection efficiency (CCE). Also the reconstructive effect of annealing on radiation induced damage was tested for CdTe detector.

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

2009-07-01

418

Results from the Medipix-2 and Timepix Ionizing Radiation Imaging Detectors on BEXUS stratospheric balloon student campaigns  

NASA Astrophysics Data System (ADS)

Results of the first two experiments using the semiconductor pixel detectors of the Medipix fam-ily for energetic particle imaging in the stratospheric environment are presented. The original detecting device was based on the hybrid pixel detectors of Medipix-2 and Timepix developed at CERN with USB interface developed at Institute of Experimental and Applied Physics of Czech Technical University in Prague. The detectors were used in tracking mode allowing them to operate as an active nuclear emulsion". The actual flight time of BEXUS7 with Medipix-2 on 8th October 2008 was over 4 hours, with 2 hours at stable floating altitude of 26km. BEXUS9 measurements of 3.5 hour duration by Timepix, Medipix-2 and ST-6 Geiger telescope instruments took place in arctic atmosphere till ceiling altitude of 24km on 11th October 2009. Stratospheric balloon platform is the optimal realization for all in-situ measurements of atmo-spheric electricity. Not only because of the high altitudes reached, but also due to its slow ascent velocity for statistically relevant sampling of the ambient environment for improving cosmic ray induced ionisation rate model inputs. The flight opportunity for BEXUS student projects was provided by Education department of the European Space Agency (ESA) and Eu-rolaunch -Collaboration of Swedish National Space Board (SNSB) and German Space Agency (DLR). The scientific goal was to check energetic particle type altitudinal dependencies, si-multaneously testing proper detector calibration by detecting fluxes of ionizing radiation while evaluating instrumentation endurance and performance.

Urbar, Jaroslav; Scheirich, Jan; Jakubek, Jan

419

Microfluidic beta and conversion electron radiation detector for preclinical pharmacokinetic studies with PET and SPECT radiotracers  

Microsoft Academic Search

The characterization of new radiotracer pharmacokinetics in small animals is very challenging because of the small volume of blood available. For this purpose, a microfluidic blood counter prototype made of a microchannel on silicon containing PIN photodiodes was proposed to improve beta detection efficiency in a small volume by eliminating all unnecessary interfaces between blood and detector. In this work,

L. Convert; F. Girard-Baril; V. Boisselle; J.-F. Pratte; R. Fontaine; V. Aimez; P. Charette; R. Lecomte

2010-01-01

420

Modular sensor pack for large thickness cadmium zinc telluride (CZT) Gamma Radiation detectors  

Microsoft Academic Search

The high cost of fine spectroscopic grade CZT crystals with large gamma-ray stopping power is a limiting factor for widespread utilization in detector applications. Large volume, monolithic crystal parts suffer a lower yield because of high probability of defect opportunities. This work demonstrates a modular construction technique where volumetric scaling laws are overcome. Smaller crystal tiles are individually diced, graded

T. Zhang; J. E. Tkaczyk; K. Andreini; F. Pan; Y. Z. Williams; Y. Du; H. Chen; G. Bindley

2010-01-01