Science.gov

Sample records for active detector area

  1. Impact of detector-element active-area shape and fill factor on super-resolution

    NASA Astrophysics Data System (ADS)

    Hardie, Russell; Droege, Douglas; Dapore, Alexander; Greiner, Mark

    2015-05-01

    In many undersampled imaging systems, spatial integration from the individual detector elements is the dominant component of the system point spread function (PSF). Conventional focal plane arrays (FPAs) utilize square detector elements with a nearly 100% fill factor, where fill factor is defined as the fraction of the detector element area that is active in light detection. A large fill factor is generally considered to be desirable because more photons are collected for a given pitch, and this leads to a higher signal-to-noise-ratio (SNR). However, the large active area works against super-resolution (SR) image restoration by acting as an additional low pass filter in the overall PSF when modeled on the SR sampling grid. A high fill factor also tends to increase blurring from pixel cross-talk. In this paper, we study the impact of FPA detector-element shape and fill factor on SR. A detailed modulation transfer function analysis is provided along with a number of experimental results with both simulated data and real data acquired with a midwave infrared (MWIR) imaging system. We demonstrate the potential advantage of low fill factor detector elements when combined with SR image restoration. Our results suggest that low fill factor circular detector elements may be the best choice. New video results are presented using robust adaptive Wiener filter SR processing applied to data from a commercial MWIR imaging system with both high and low detector element fill factors.

  2. Activation detector

    DOEpatents

    Bell, Zane William [Oak Ridge, TN; Boatner, Lynn Allen [Oak Ridge, TN

    2009-12-08

    A method of detecting an activator, the method including impinging with an activator a receptor material lacking a photoluminescent material and generating a by-product of a radioactive decay due to the activator impinging the reeptor material. The method further including, generating light from the by-product via the Cherenkov effect and identifying a characteristic of the activator based on the light.

  3. Ultrafast superconducting single-photon detector with a reduced active area coupled to a tapered lensed single-mode fiber

    NASA Astrophysics Data System (ADS)

    Sidorova, Maria V.; Divochiy, Alexander V.; Vakhtomin, Yury B.; Smirnov, Konstantin V.

    2015-01-01

    This paper presents an ultrafast niobium nitride (NbN) superconducting single-photon detector (SSPD) with an active area of 3×3 μm2 that offers better timing performance metrics than the previous SSPD with an active area of 7×7 μm2. The improved SSPD demonstrates a record timing jitter (<25 ps), an ultrashort recovery time (<2 ns), an extremely low dark count rate, and a high detection efficiency in a wide spectral range from visible part to near infrared. The record parameters were obtained due to the development of a new technique providing effective optical coupling between a detector with a reduced active area and a standard single-mode telecommunication fiber. The advantages of the new approach are experimentally confirmed by taking electro-optical measurements.

  4. Determination of the specific alpha activity of thick sources with a large area ZnS(Ag) scintillation detector.

    PubMed

    Djurasević, M; Vukanac, I; Kandić, A; Nadderd, L; Milosević, Z; Radenković, M

    2007-01-01

    A method for determining the specific alpha activity of thick sources using a large area ZnS(Ag) scintillation detector is presented. In this method a quadratic relationship between the detector response and window thickness is assumed. This method provides a quick estimation of alpha activity in the sample, so it is an indicative method. The aim of this experimental work is to approve theoretical assumption and to develop a standard routine method for absolute alpha measurements of thick contaminated environmental sources. For this purpose reference material U(3)O(8) and spiked standards of soil were used. Measurements of contaminated soil samples from south Serbia showed the practical application of this method. PMID:17383779

  5. Arsenic activation neutron detector

    DOEpatents

    Jacobs, Eddy L.

    1981-01-01

    A detector of bursts of neutrons from a deuterium-deuteron reaction includes a quantity of arsenic adjacent a gamma detector such as a scintillator and photomultiplier tube. The arsenic is activated by the 2.5 Mev neutrons to release gamma radiation which is detected to give a quantitative representation of detected neutrons.

  6. Arsenic activation neutron detector

    DOEpatents

    Jacobs, E.L.

    1980-01-28

    A detector of bursts of neutrons from a deuterium-deuteron reaction includes a quantity of arsenic adjacent a gamma detector such as a scintillator and photomultiplier tube. The arsenic is activated by the 2.5-MeV neutrons to release gamma radiation which is detected to give a quantitative representation of detected neutrons.

  7. Ultrafast superconducting single-photon detector with reduced-size active area coupled to a tapered lensed single-mode fiber

    NASA Astrophysics Data System (ADS)

    Sidorova, Maria V.; Divochiy, Alexander; Vachtomin, Yury B.; Smirnov, Konstantin V.

    2015-05-01

    We present an ultrafast NbN Superconducting single-photon detector (SSPD) with active area of 3x3 μm2, which reveals better timing performances than a previously developed SSPD with active area of 10x10 μm2. The improved SSPD demonstrates the record timing jitter <25 ps, ultra short recovery time <2 ns, extremely low dark counts level, and high detection efficiency (DE) in a wide spectral range from visible to near-infrared. The record parameters were obtained thanks to the development of a new technique of an effective optical coupling between a detector with reduced-size active area and a standard single-mode telecommunication fiber. The advantages of a new approach are experimentally confirmed by performed electro-optical measurements of the device performances.

  8. areaDetector: Software for 2-D Detectors in EPICS

    SciTech Connect

    Rivers, M.

    2011-09-23

    areaDetector is a new EPICS module designed to support 2-D detectors. It is modular C++ code that greatly simplifies the task of writing support for a new detector. It also supports plugins, which receive detector data from the driver and process it in some way. Existing plugins perform Region-Of-Interest extraction and analysis, file saving (in netCDF, HDF, TIFF and JPEG formats), color conversion, and export to EPICS records for image display in clients like ImageJ and IDL. Drivers have now been written for many of the detectors commonly used at synchrotron beamlines, including CCDs, pixel array and amorphous silicon detectors, and online image plates.

  9. areaDetector: Software for 2-D Detectors in EPICS

    SciTech Connect

    Rivers, Mark L.

    2010-06-23

    areaDetector is a new EPICS module designed to support 2-D detectors. It is modular C++ code that greatly simplifies the task of writing support for a new detector. It also supports plugins, which receive detector data from the driver and process it in some way. Existing plugins perform Region-Of-Interest extraction and analysis, file saving (in netCDF, HDF, TIFF and JPEG formats), color conversion, and export to EPICS records for image display in clients like ImageJ and IDL. Drivers have now been written for many of the detectors commonly used at synchrotron beamlines, including CCDs, pixel array and amorphous silicon detectors, and online image plates.

  10. ISABELLE. Volume 3. Experimental areas, large detectors

    SciTech Connect

    Not Available

    1981-01-01

    This section presents the papers which resulted from work in the Experimental Areas portion of the Workshop. The immediate task of the group was to address three topics. The topics were dictated by the present state of ISABELLE experimental areas construction, the possibility of a phased ISABELLE and trends in physics and detectors.

  11. Large area position sensitive β-detector

    NASA Astrophysics Data System (ADS)

    Vaintraub, S.; Hass, M.; Edri, H.; Morali, N.; Segal, T.

    2015-03-01

    A new conceptual design of a large area electron detector, which is position and energy sensitive, was developed. This detector is designed for beta decay energies up to 4 MeV, but in principle can be re-designed for higher energies. The detector incorporates one large plastic scintillator and, in general, a limited number of photomultipliers (7 presently). The current setup was designed and constructed after an extensive Geant4 simulation study. By comparison of a single hit light distribution between the various photomultipliers to a pre-measured accurate position-response map, the anticipated position resolution is around 5 mm. The first benchmark experiments have been conducted in order to calibrate and confirm the position resolution of the detector. The new method, results of the first test experiments and comparison to simulations are presented.

  12. Characterization of imaging performance of a large-area CMOS active-pixel detector for low-energy X-ray imaging

    NASA Astrophysics Data System (ADS)

    Hwy Lim, Chang; Yun, Seungman; Chul Han, Jong; Kim, Ho Kyung; Farrier, Michael G.; Graeve Achterkirchen, Thorsten; McDonald, Mike; Cunningham, Ian A.

    2011-10-01

    We report the imaging characteristics of the recently developed large-area complementary metal-oxide-semiconductor (CMOS) active-pixel detector for low-energy digital X-ray imaging applications. The detector consists of a scintillator to convert X-ray into light and a photodiode pixel array made by the CMOS fabrication process to convert light into charge signals. Between two layers, we introduce a fiber-optic faceplate (FOP) to avoid direct absorption of X-ray photons in the photodiode array. A single pixel is composed of a photodiode and three transistors, and the pixel pitch is 96 μm. The imaging characteristics of the detector have been investigated in terms of modulation-transfer function (MTF), noise-power spectrum (NPS), and detective quantum efficiency (DQE). From the measured results, the MTF at the Nyquist frequency is about 20% and the DQE around zero-spatial frequency is about 40%. Simple cascaded linear-systems analysis has showed that the FOP prevents direct absorption of X-ray photons within the CMOS photodiode array, leading to a lower NPS and consequently improved DQE especially at high spatial frequencies.

  13. Active Pyroelectric Infrared Detector

    NASA Technical Reports Server (NTRS)

    Zuckerwar, Allan J. (Inventor); Zalameda, Joseph N. (Inventor); Mina, Joseph M. (Inventor)

    1995-01-01

    A noncontact pyroelectric infrared detector is described. A pyroelectric film that also has piezoelectric properties is held in place so that it is free to vibrate. It is electrically stimulated to vibrate at a resonance frequency. The vibrating film forms part of a balanced bridge circuit. As thermal radiation impinges on the film the pyroelectric effect causes the resonance frequency to change, thereby unbalancing the bridge circuit. A differential amplifier tracks the change in voltage across the bridge. The resulting voltage signal is further processed by a bandpass filter and a precision rectifier. The device allows for DC or static temperature measurements without the use of a mechanical chopping device.

  14. The CLAS12 large area RICH detector

    SciTech Connect

    M. Contalbrigo, E. Cisbani, P. Rossi

    2011-05-01

    A large area RICH detector is being designed for the CLAS12 spectrometer as part of the 12 GeV upgrade program of the Jefferson Lab Experimental Hall-B. This detector is intended to provide excellent hadron identification from 3 GeV/c up to momenta exceeding 8 GeV/c and to be able to work at the very high design luminosity-up to 1035 cm2 s-1. Detailed feasibility studies are presented for two types of radiators, aerogel and liquid C6F14 freon, in conjunction with a highly segmented light detector in the visible wavelength range. The basic parameters of the RICH are outlined and the resulting performances, as defined by preliminary simulation studies, are reported.

  15. Centroid tracking with area array detectors

    NASA Technical Reports Server (NTRS)

    Glavich, T. A.

    1986-01-01

    A computer program (ALGEVAL) has been developed to simulate the position estimating behavior of a centroid estimator algorithm using data typical of optical point spread function data recorded by an area array detector. Typical results are shown of varying detector properties and optical point spread function types. The detector parameters currently available for study include read noise mean value, dark current mean value and spatial variation, charge transfer efficiency and point spread function location, saturation level, signal level and pixel size. The program is capable of calculating any order centroid using an array size from 2 x 2 to 15 x 15 pixels. The output of the program is either a performance map, histogram data or tabluar data. A number of further developments are recommended.

  16. Dynamic cardiac volume imaging using area detectors

    NASA Astrophysics Data System (ADS)

    Bruder, Herbert; Hoelzel, Arne; Stierstorfer, Karl; Rauscher, Annabella; Flohr, Thomas

    2003-05-01

    We present a reconstruction scheme for dynamic cardiac volume imaging using Area Detector Computed Tomography (CT) named Multi-Sector Cardiac Volume Reconstruction (MCVR) which is based on a 3D-backprojection of the Feldkamp-type. It is intended for circular scanning using area detectors covering the whole heart volume, but the method can easily be extended to cardiac spiral imaging using multi-slice CT. In cardiac imaging with multi-slice CT continuous data acquisition combined with the parallel recording of the patient's ECG enables retrospective gating of data segments for image reconstruction. Using consecutive heart cycles MCVR identifies complementary and time consistent projection data segments <= π using temporal information of the ECG. After a row by row parallel rebinning and temporal rebinning the projection data have to be filtered using conventional convolution kernels and finally reconstructed to image space using a 3D-backprojection. A dynamic anthropomorphic computer model of the human heart was developed in order to validate the MCVR approach. A 256-slice detector system with 0.5mm slice collimation was simulated operating in a circular scanning mode at a gantry rotation time of 330ms and compared to state-of-the-art 16-slice technology. At enddiastole the coronary anatomy can be visualized with excellent image quality. Although an area detector with large cone angling covering the entire heart volume was used no cone-artifacts could be observed. Using a 2-sector approach a nearly motion free 3D visualization of the heart chambers was obtained even at endsystole.

  17. Large area 200 psec gated microchannel plate detector

    SciTech Connect

    Eckart, M.J.; Hanks, R.L.; Kilkenny, J.D.; Pasha, R.; Wiedwald, J.D.; Hares, J.D.

    1986-03-01

    Results are presented with a 15 mm wide gated microchannel plate uv and x-ray detector. The active area is part of a 6 ohm transmission line driven by an electronically generated gate pulse. The microchannel plate is coated with CsI allowing tests with a frequency quadrupled, high repetition rate 1.05 ..mu..m laser. Results showing optical gate widths as short as 100 psec are presented.

  18. Large-area 200-ps gated microchannel plate detector

    SciTech Connect

    Eckart, M.J.; Hanks, R.L.; Kilkenny, J.D.; Pasha, R.; Wiedwald, J.D.; Hares, J.D.

    1986-08-01

    Results are presented with a 15-mm-wide gated microchannel plate UV and x-ray detector. The active area is part of a 6-..cap omega.. transmission line driven by an electronically generated gate pulse. The microchannel plate is coated with CsI allowing tests with a frequency-quadrupoled, high-repetition-rate 1.05-..mu..m laser. Results showing optical gate widths as short as 100 ps are presented.

  19. Performance of a Medium-Size Area nGEM Detector for Neutron Beam Diagnostics

    NASA Astrophysics Data System (ADS)

    Croci, G.; Cazzaniga, C.; Albani, G.; Muraro, A.; Claps, G.; Cavenago, M.; Grosso, G.; Murtas, F.; Pasqualotto, R.; Cippo, E. Perelli; Rebai, M.; Tardocchi, M.; Gorini, G.

    Fast neutron detectors with a sub-centimetric space resolution are required in order to qualify neutron beams in applications related to magnetically-controlled nuclear fusion plasmas and to spallation sources. Based on the results obtained with small area prototypes, the first medium-size (20 x 35.2 cm2 active area) nGEM detector has been realized for both the CNESM diagnostic system of the SPIDER NBI prototype for ITER and as a beam monitor for fast neutrons beam lines at spallation sources, too. The nGEM is a Triple GEM gaseous detector equipped with polyethylene layers used to convert fast neutrons into recoil protons through the elastic scattering process. This paper describes the performance of the medium-size nGEM detector tested at the VESUVIO beam line of the ISIS spallation source. Being this detector the actual largest area fast neutron detector based on the GEM technology, particular attention was paid in the study of detector response in different points over the active area. Measurements of GEM counting rate (both as a function of VGEM and of time) and of the capability of the detector to reconstruct the beam in different positions are presented. This detector serves as a basis for the realization of an even larger area detector that will be used in the MITICA NBI prototype for ITER that represents the evolution of SPIDER.

  20. Area detectors in single-crystal neutron diffraction

    NASA Astrophysics Data System (ADS)

    McIntyre, Garry J.

    2015-12-01

    The introduction of area detectors has brought about a gentle revolution in the routine application of single-crystal neutron diffractometry. Implemented first for macromolecular crystallography, electronic detectors subsequently gradually spread to chemical and physics-oriented crystallography at steady-state sources. The volumetric surveying of reciprocal space implicit in the Laue technique has required area detectors right from the start, whether using film and more recently image plates and CCD-based detectors at reactors, or scintillation detectors at spallation sources. Wide-angle volumetric data collection has extended application of neutron single-crystal diffractometry to chemical structures, sample volumes, and physical phenomena previously deemed impossible. More than 30 of the dedicated single-crystal neutron diffractometers at steady-state reactor and neutron spallation sources worldwide and accessible via peer-review proposal mechanisms are currently equipped with area detectors. Here we review the historical development of the various types of area detectors used for single crystals, discuss experimental aspects peculiar to experiments with such detectors, highlight the scientific fields where the use of area detectors has had a special impact, and forecast future developments in hardware, implementation, and software.

  1. A three dimensionally position sensitive large area detector

    NASA Astrophysics Data System (ADS)

    Pochodzalla, J.; Butsch, R.; Heck, B.; Hlawatsch, G.; Miczaika, A.; Rabe, H. J.; Rosner, G.

    1985-01-01

    A large area detector consisting of a parallel plate avalanche counter (PPAC) and a trapezohedral ionization chamber (TIC) is described. Its active area is 184 cm 2. The time resolution of the PPAC is 175 ps. The energy resolution of the TIC is 0.4%, the energy loss resolution 2.8%, the nuclear charge resolution 2.3%. The TIC is position sensitive in three dimensions. The position x is measured via a saw-tooth anode with a resolution of 0.7 mm; the drift time coordinate shows a resolution of δy ≅ mm. The range z is determined by a new technique, a graded density Frisch grid. It enlarges the dynamic range of the charge measurement down to the Bragg maximum at E/ A ˜ 1 MeV. The resolution is δZ/ Z ≅ 3.5%

  2. Small area silicon diffused junction x-ray detectors

    SciTech Connect

    Walton, J.T.; Pehl, R.H.; Larsh, A.E.

    1981-10-01

    The low temperature performance of silicon diffused junction detectors in the measurement of low energy x-rays is reported. The detectors have an area of 0.04 cm/sup 2/ and a thickness of 100 ..mu..m. The spectral resolutions of these detectors were found to be in close agreement with expected values indicating that the defects introduced by the high temperature processing required in the device fabrication were not deleteriously affecting the detection of low energy x-rays. Device performance over a temperature range of 77 to 150/sup 0/K is given. These detectors were designed to detect low energy x-rays in the presence of minimum ionizing electrons. The successful application of silicon diffused junction technology to x-ray detector fabrication may facilitate the development of other novel silicon x-ray detector designs.

  3. A large area detector for x-ray applications

    SciTech Connect

    Rodricks, B.; Huang, Qiang; Hopf, R.; Wang, Kemei

    1993-10-01

    A large area detector for x-ray synchrotron applications has been developed. The front end of this device consist of a scintillator coupled to a fiber-optic taper. The fiber-optic taper is comprised of 4 smaller (70 mm x 70 mm) tapers fused together in a square matrix giving an active area of 140 mm x 140 mm. Each taper has a demagnification of 5.5 resulting in four small ends that are 12 mm diagonally across. The small ends of each taper are coupled to four microchannel-plate-based image intensifiers. The output from each image intensifier is focused onto a Charge Coupled Device (CCD) detector. The four CCDs are read out in parallel and are independently controlled. The image intensifiers also act as fast (20 ns) electronic shutters. The system is capable of displaying images in real time. Additionally, with independent control on the readout of each row of data from the CCD, the system is capable of performing high speed imaging through novel readout manipulation.

  4. Detective quantum efficiency of electron area detectors in electron microscopy

    PubMed Central

    McMullan, G.; Chen, S.; Henderson, R.; Faruqi, A.R.

    2009-01-01

    Recent progress in detector design has created the need for a careful side-by-side comparison of the modulation transfer function (MTF) and resolution-dependent detective quantum efficiency (DQE) of existing electron detectors with those of detectors based on new technology. We present MTF and DQE measurements for four types of detector: Kodak SO-163 film, TVIPS 224 charge coupled device (CCD) detector, the Medipix2 hybrid pixel detector, and an experimental direct electron monolithic active pixel sensor (MAPS) detector. Film and CCD performance was measured at 120 and 300 keV, while results are presented for the Medipix2 at 120 keV and for the MAPS detector at 300 keV. In the case of film, the effects of electron backscattering from both the holder and the plastic support have been investigated. We also show that part of the response of the emulsion in film comes from light generated in the plastic support. Computer simulations of film and the MAPS detector have been carried out and show good agreement with experiment. The agreement enables us to conclude that the DQE of a backthinned direct electron MAPS detector is likely to be equal to, or better than, that of film at 300 keV. PMID:19497671

  5. Characterization of Large Area APDs for the EXO-200 Detector

    SciTech Connect

    Neilson, R.; LePort, F.; Pocar, A.; Kumar, K.; Odian, A.; Prescott, C.Y.; Tenev, V.; Ackerman, N.; Akimov, D.; Auger, M.; Benitez-Medina, C.; Breidenbach, M.; Burenkov, A.; Conley, R.; Cook, S.; deVoe, R.; Dolinski, M.J.; Fairbank, W., Jr.; Farine, J.; Fierlinger, P.; Flatt, B.; /Stanford U., Phys. Dept. /Bern U., LHEP /Stanford U., Phys. Dept. /Maryland U. /Colorado State U. /Laurentian U. /Carleton U. /SLAC /Maryland U. /Moscow, ITEP /Alabama U. /SLAC /Colorado State U. /Stanford U., Phys. Dept. /Alabama U. /Stanford U., Phys. Dept. /Alabama U. /SLAC /Carleton U. /SLAC /Maryland U. /Moscow, ITEP /Carleton U. /Stanford U., Phys. Dept. /Bern U., LHEP /SLAC /Laurentian U. /SLAC /Maryland U.

    2011-12-02

    EXO-200 uses 468 large area avalanche photodiodes (LAAPDs) for detection of scintillation light in an ultra-low-background liquid xenon (LXe) detector. We describe initial measurements of dark noise, gain and response to xenon scintillation light of LAAPDs at temperatures from room temperature to 169 K - the temperature of liquid xenon. We also describe the individual characterization of more than 800 LAAPDs for selective installation in the EXO-200 detector.

  6. Large Area Dust Detector onboard Solar Power Sail Spacecraft

    NASA Astrophysics Data System (ADS)

    Yano, Hajime

    JAXA is aiming to launch the solar power sail engineering demonstrator to the outer planet region of the solar system like Jupiter and the Jovian Trojan asteroids in 2010's. Its interplanetary cruise is a relevant and rare opportunity to monitor physical properties that may be varied by heliocentric distances continuously such as solar wind, solar magnetosphere and micrometeoroid flux. We have been developing the largest but still light-weight dust detector ever to be onboard deep space probes since 2000. PVDF films of a few to 10's of micron thickness are attached as a small part of the solar sail membrane to count and time hypervelocity impacts by micrometeoroids larger than micron size. The first spaceflight test of this dust detector in the order of 100 cm2 detection area was conducted onboard SSSAT (Solar Sail Satellite) as the M-V sub-payload launched to LEO in September 2006. The second opportunity of this series will be the 4- channel impact sensors onboard Kagayaki nano-satellite as an H-IIA piggyback to be launched in 2008. Actual interplanetary measurements can be achieved by the Small Solar Power Sail Demonstrator that will go inside the orbit of the Earth (1 AU) close to Venus around 2010. On this spacecraft, the 8-channel PVDF sensors of about 1 m2 detection area will be onboard to test this system in the interplanetary operation and to hopefully measure dust flux anisotropy in the trailing edge of the Earth, heliocentric flux variance inside 1 AU, and opportunistic detections of possible cometary dust trails and flux enhancement near Venus. The sensors filter electronic, thermal and vibration noises and record time, peak hold value, and relax duration of signals of micrometeoroid impacts. When the full-size solar power sail mission goes beyond 1 AU passing the main asteroid belt to 5 AU in 2010's, this dust detector system will be onboard in the order of several m2 active area. It will also compare its results with infrared observation of zodiacal

  7. Large area silicon drift detectors for x-rays -- New results

    SciTech Connect

    Iwanczyk, J.S.; Patt, B.E.; Tull, C.R.; Segal, J.D.; Kenney, C.J.; Bradley, J.; Hedman, B.; Hodgson, K.O.

    1999-06-01

    Large area silicon drift detectors, consisting of 8 mm and 12 mm diameter hexagons, were fabricated on 0.35 mm thick high resistivity n-type silicon. An external FET and a low-noise charge sensitive preamplifier were used for testing the prototype detectors. The detector performance was measured in the range {minus}75 to 25 C using Peltier cooling, and from 0.125 to 6 {micro}s amplifier shaping time. Measured energy resolutions were 159 eV FWHM and 263 eV FWHM for the 0.5 cm{sup 2} and 1 cm{sup 2} detectors, respectively (at 5.9 keV, {minus}75 C, 6 {micro}s shaping time). The uniformity of the detector response over the entire active area (measured using 560 nm light) was <0.5%.

  8. Large area silicon drift detectors for x-rays -- New results

    SciTech Connect

    Iwanczyk, J.S.; Patt, B.E.; Tull, C.R.; Segal, J.D.; Kenney, C.J.; Bradley, J.; Hedman, B.; Hodgson, K.O.

    1998-12-31

    Large area silicon drift detectors, consisting of 8 mm and 12 mm diameter hexagons, were fabricated on 0.35 mm thick high resistivity n-type silicon. An external FET and a low-noise charge sensitive preamplifier were used for testing the prototype detectors. The detector performance was measured in the range 75 to 25 C using Peltier cooling, and from 0.125 to 6 {micro}s amplifier shaping time. Measured energy resolutions were 159 eV FWHM and 263 eV FWHM for the 0.5 cm{sup 2} and 1 cm{sup 2} detectors, respectively (at 5.9 keV, {minus}75 C, 6 {micro}s shaping time). The uniformity of the detector response over the entire active area (measured using 560 nm light) was < 0.5%.

  9. Novel Silicon Carbide Detector for Active Inspections

    SciTech Connect

    F. H. Ruddy; J.G. Seidel; R.W. Flammang

    2007-03-01

    The need to address increasingly challenging inspection requirements (such as large volume objects, very fast inspection throughputs, potentially significant shielding, etc.) for such items as nuclear materials and explosives will require the use of active interrogation technologies. While these active technologies can successfully address these challenges by inducing unique, temporal signatures, the inspection environment will also induce overall “background signals” that can be orders of magnitude larger than the induced signatures. Detectors that can successfully operate in these types of customized, inspection environments (pulsed and continuous) and successfully extract induced signature data are clearly needed and will effectively define the limitations of any active inspection system. A novel silicon carbide detector is now being investigated to successfully address both neutron- and photon/bremsstrahlung-type inspection applications. While this paper describes this detector and highlights efforts related to neutron inspection, it will focus on its neutron and gamma-ray/photon detection performance in neutron- and bremssstrahlung-type inspection applications.

  10. Imaging performance of amorphous selenium based flat-panel detectors for digital mammography: characterization of a small area prototype detector.

    PubMed

    Zhao, Wei; Ji, W G; Debrie, Anne; Rowlands, J A

    2003-02-01

    Our work is to investigate and understand the factors affecting the imaging performance of amorphous selenium (a-Se) flat-panel detectors for digital mammography. Both theoretical and experimental methods were developed to investigate the spatial frequency dependent detective quantum efficiency [DQE(f)] of a-Se flat-panel detectors for digital mammography. Since the K edge of a-Se is 12.66 keV and within the energy range of a mammographic spectrum, a theoretical model was developed based on cascaded linear system analysis with parallel processes to take into account the effect of K fluorescence on the modulation transfer function (MTF), noise power spectrum (NPS), and DQE(f) of the detector. This model was used to understand the performance of a small-area prototype detector with 85 microm pixel size. The presampling MTF, NPS, and DQE(f) of the prototype were measured, and compared to the theoretical calculation of the model. The calculation showed that K fluorescence accounted for a 15% reduction in the MTF at the Nyquist frequency (fNy) of the prototype detector, and the NPS at fNy was reduced to 89% of that at zero spatial frequency. The measurement of presampling MTF of the prototype detector revealed an additional source of blurring, which was attributed to charge trapping in the blocking layer at the interface between a-Se and the active matrix. This introduced a drop in both presampling MTF and NPS at high spatial frequency, and reduced aliasing in the NPS. As a result, the DQE(f) of the prototype detector at fNy approached 40% of that at zero spatial frequency. The measured and calculated DQE(f) using the linear system model have reasonable agreement, indicating that the factors controlling image quality in a-Se based mammographic detectors are fully understood, and the model can be used to further optimize detector imaging performance. PMID:12607843

  11. The Anti-Coincidence Detector for the GLAST Large Area Telescope

    SciTech Connect

    Moiseev, A.A.; Hartman, R.C.; Ormes, J.F.; Thompson, D.J.; Amato, M.J.; Johnson, T.E.; Segal, K.N.; Sheppard, D.A.

    2007-03-23

    This paper describes the design, fabrication and testing of the Anti-Coincidence Detector (ACD) for the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT). The ACD is LAT's first-level defense against the charged cosmic ray background that outnumbers the gamma rays by 3-5 orders of magnitude. The ACD covers the top and 4 sides of the LAT tracking detector, requiring a total active area of {approx}8.3 square meters. The ACD detector utilizes plastic scintillator tiles with wave-length shifting fiber readout. In order to suppress self-veto by shower particles at high gamma-ray energies, the ACD is segmented into 89 tiles of different sizes. The overall ACD efficiency for detection of singly charged relativistic particles entering the tracking detector from the top or sides of the LAT exceeds the required 0.9997.

  12. Synchrotron Area X-ray Detectors, Present and Future

    SciTech Connect

    Gruner, Sol M.

    2010-06-23

    X-ray experiments are very frequently detector limited at today's storage ring synchrotron radiation (SR) sources, and will be even more so at future Energy Recovery Linac and X-ray Free Electron Laser sources. Image plate and phosphor-coupled CCD detectors that predominate at present-day sources were outgrowths of technologies initially developed for the medical and astronomical communities, respectively, with resultant limitations for SR. These limitations are enumerated. The growth of commercial silicon foundries and design tools enabling the production of large, customized integrated circuits is beginning to have a profound impact on SR detectors and is ushering in the age of 'designer detectors'. Novel area Pixel Array Detectors (PADs) are starting to appear in which each pixel has dedicated, complex circuitry capable of high speed and, in some cases, significant data processing power for specific applications. PADs now at, or near the horizon will be described. Integrated circuit methods continue to develop at a rapid pace. Implications for future x-ray detectors will be discussed.

  13. Development of a Large-Area Ultracold Neutron Detector

    NASA Astrophysics Data System (ADS)

    Stoffel, Jenna; Liu, Chen-Yu; UCN Tau Collaboration

    2015-10-01

    To improve our knowledge in particle physics and cosmology, including big-bang nucleosynthesis, we need a more precise and accurate measurement of the lifetime of free neutrons. Though there have been many attempts to measure the neutron lifetime, discrepancies exist between the two major experimental techniques of the beam and the bottle methods. To resolve this discrepancy, the UCN τ experiment will trap ultracold neutrons (UCNs) to perform lifetime measurements to the 1-second level. To accomplish this goal, we are developing a large-area, high-efficiency UCN detector. We construct a scintillating UCN detector by evaporating a thin film of boron-10 onto an airbrushed layer of zinc sulfide (ZnS); the 10B-coated ZnS scintillating film is then glued to wavelength-shifting plastic, which acts as a light guide to direct photons into modern silicon photomultipliers. This new detector has similar efficiency and background noise as the previously-used ion gas detectors, but can be easily scaled up to cover large areas for many applications. The new detector opens up exciting new ways to study systematic effects, as they hold the key to the interpretation of neutron lifetime.

  14. Characterization and Calibration of Large Area Resistive Strip Micromegas Detectors

    NASA Astrophysics Data System (ADS)

    Lösel, Philipp; ATLAS Muon Collaboration

    2016-07-01

    Resistive strip Micromegas detectors have been tested extensively as small detectors of about 10×10 cm2 in size and they work reliably at high rates of 100 kHz/cm2 and above. Tracking resolution well below 100 μm has been observed for 100 GeV muons and pions. Micromegas detectors are meanwhile proposed as large area muon precision trackers of 2-3 m2 in size. To investigate possible differences between small and large detectors, a 1 m2 detector with 2048 resistive strips at a pitch of 450 μm was studied in the LMU Cosmic Ray Measurement Facility (CRMF) using two 4×2.2 m2 large Monitored Drift Tube (MDT) chambers for cosmic muon reference tracking. A segmentation of the resistive strip anode plane in 57.6 mm×93 mm large areas has been realized by the readout of 128 strips with one APV25 chip each and by eleven 93 mm broad trigger scintillators placed along the readout strips. This allows for mapping of homogeneity in pulse height and efficiency, determination of signal propagation along the 1 m long anode strips and calibration of the position of the anode strips.

  15. Position reconstruction in large-area scintillating fibre detectors

    NASA Astrophysics Data System (ADS)

    Mahata, K.; Johansson, H. T.; Paschalis, S.; Simon, H.; Aumann, T.

    2009-09-01

    A new analysis procedure has been developed for the large-area scintillating fibre detectors with position-sensitive photomultiplier (PSPM) readout used for heavy ions in the LAND set-up at GSI. It includes gain matching of the PSPM, calibration of the PSPM fibre mask and hit reconstruction. This procedure allows for a quasi-online calibration of this tracking device. It also allows for a precise determination of the position close to the intrinsic detector resolution of 1 mm pitch together with careful treatment of individual event accuracies.

  16. Large area nuclear particle detectors using ET materials, phase 2

    NASA Technical Reports Server (NTRS)

    Wrigley, Charles Y.; Storti, George M.; Walter, Lee; Mathews, Scott

    1990-01-01

    This report presents work done under a Phase 2 SBIR contract for demonstrating large area detector planes utilizing Quantex electron trapping materials as a film medium for storing high-energy nuclide impingement information. The detector planes utilize energy dissipated by passage of the high-energy nuclides to produce localized populations of electrons stored in traps. Readout of the localized trapped electron populations is effected by scanning the ET plane with near-infrared, which frees the trapped electrons and results in optical emission at visible wavelengths. The effort involved both optimizing fabrication technology for the detector planes and developing a readout system capable of high spatial resolution for displaying the recorded nuclide passage tracks.

  17. Background simulations for the Large Area Detector onboard LOFT

    NASA Astrophysics Data System (ADS)

    Campana, Riccardo; Feroci, Marco; Del Monte, Ettore; Mineo, Teresa; Lund, Niels; Fraser, George W.

    2013-12-01

    The Large Observatory For X-ray Timing (LOFT), currently in an assessment phase in the framework the ESA M3 Cosmic Vision programme, is an innovative medium-class mission specifically designed to answer fundamental questions about the behaviour of matter, in the very strong gravitational and magnetic fields around compact objects and in supranuclear density conditions. Having an effective area of ˜10 m2 at 8 keV, LOFT will be able to measure with high sensitivity very fast variability in the X-ray fluxes and spectra. A good knowledge of the in-orbit background environment is essential to assess the scientific performance of the mission and optimize the design of its main instrument, the Large Area Detector (LAD). In this paper the results of an extensive Geant-4 simulation of the instrumentwillbe discussed, showing the main contributions to the background and the design solutions for its reduction and control. Our results show that the current LOFT/LAD design is expected to meet its scientific requirement of a background rate equivalent to 10 mCrab in 2‒30 keV, achieving about 5 mCrab in the most important 2-10 keV energy band. Moreover, simulations show an anticipated modulation of the background rate as small as 10 % over the orbital timescale. The intrinsic photonic origin of the largest background component also allows for an efficient modelling, supported by an in-flight active monitoring, allowing to predict systematic residuals significantly better than the requirement of 1 %, and actually meeting the 0.25 % science goal.

  18. Large area x-ray detectors for cargo radiography

    NASA Astrophysics Data System (ADS)

    Bueno, C.; Albagli, D.; Bendahan, J.; Castleberry, D.; Gordon, C.; Hopkins, F.; Ross, W.

    2007-04-01

    Large area x-ray detectors based on phosphors coupled to flat panel amorphous silicon diode technology offer significant advances for cargo radiologic imaging. Flat panel area detectors provide large object coverage offering high throughput inspections to meet the high flow rate of container commerce. These detectors provide excellent spatial resolution when needed, and enhanced SNR through low noise electronics. If the resolution is reduced through pixel binning, further advances in SNR are achievable. Extended exposure imaging and frame averaging enables improved x-ray penetration of ultra-thick objects, or "select-your-own" contrast sensitivity at a rate many times faster than LDAs. The areal coverage of flat panel technology provides inherent volumetric imaging with the appropriate scanning methods. Flat panel area detectors have flexible designs in terms of electronic control, scintillator selection, pixel pitch, and frame rates. Their cost is becoming more competitive as production ramps up for the healthcare, nondestructive testing (NDT), and homeland protection industries. Typically used medical and industrial polycrystalline phosphor materials such as Gd2O2S:Tb (GOS) can be applied to megavolt applications if the phosphor layer is sufficiently thick to enhance x-ray absorption, and if a metal radiator is used to augment the quantum detection efficiency and reduce x-ray scatter. Phosphor layers ranging from 0.2-mm to 1-mm can be "sandwiched" between amorphous silicon flat panel diode arrays and metal radiators. Metal plates consisting of W, Pb or Cu, with thicknesses ranging from 0.25-mm to well over 1-mm can be used by covering the entire area of the phosphor plate. In some combinations of high density metal and phosphor layers, the metal plate provides an intensification of 25% in signal due to electron emission from the plate and subsequent excitation within the phosphor material. This further improves the SNR of the system.

  19. A study on large area Hamamatsu photomultipliers for Cherenkov neutrino detectors

    NASA Astrophysics Data System (ADS)

    Leonora, E.; Aiello, S.; Giordano, V.; Randazzo, N.; Lo Presti, D.; Bonanno, D.; Longhitano, F.; Sipala, V.

    2015-11-01

    Many of the existing neutrino telescopes use large area photomultipliers integrated into transparent glass vessels to make the detection element called ``optical module''. The characteristics of the photomultipliers have a severe impact on the performance of the whole detectors. This paper describes a large work of characterization of large area photomultipliers performed in the frame of R&D activities of large volume underwater neutrino detectors. Dedicated studies are also reported about noise pulses, super bialkali photocathode photomultipliers, ageing effects, influences of the Earth's magnetic field and on the effects of the external glass vessels on the optical module's noise pulses.

  20. Development of LAMBDA: Large Area Medipix-Based Detector Array

    NASA Astrophysics Data System (ADS)

    Pennicard, David; Lange, Sabine; Smoljanin, Sergej; Becker, Julian; Hirsemann, Helmut; Epple, Michael; Graafsma, Heinz

    2011-11-01

    The Medipix3 photon counting readout chip has a range of features — small pixel size, high readout rate and inter-pixel communication — which make it attractive for X-ray scattering and imaging at synchrotrons. DESY have produced a prototype large-area detector module that can carry a 6 by 2 array of Medipix3 chips (1536 by 512 pixels), which can be used with a single large silicon sensor (85mm by 28mm) or two ``hexa'' high-Z sensors. The detector head is designed to be tilable and compatible with low temperatures, and will allow high speed parallel readout of the Medipix3 chips. It consists of a ceramic board, on which the sensor assembly is mounted, and a secondary board for signal routing and voltage regulators. A prototype DAQ board using USB2 readout has also been produced. A ``quad'' Medipix3 sensor assembly has been mounted on the detector head, and successfully configured and read out by the DAQ board. Development has begun on a high-speed readout board, and large-area silicon assemblies are in production.

  1. Explosively activated egress area

    NASA Technical Reports Server (NTRS)

    Bement, L. J.; Bailey, J. W. (Inventor)

    1983-01-01

    A lightweight, add on structure which employs linear shaped pyrotechnic charges to smoothly cut an airframe along an egress area periphery is provided. It compromises reaction surfaces attached to the exterior surface of the airframe's skin and is designed to restrict the skin deflection. That portion of the airframe within the egress area periphery is jettisoned. Retention surfaces and sealing walls are attached to the interior surface of the airframe's skin and are designed to shield the interior of the aircraft during detonation of the pyrotechnic charges.

  2. Indirectly illuminated X-ray area detector for X-ray photon correlation spectroscopy.

    PubMed

    Shinohara, Yuya; Imai, Ryo; Kishimoto, Hiroyuki; Yagi, Naoto; Amemiya, Yoshiyuki

    2010-11-01

    An indirectly illuminated X-ray area detector is employed for X-ray photon correlation spectroscopy (XPCS). The detector consists of a phosphor screen, an image intensifier (microchannel plate), a coupling lens and either a CCD or CMOS image sensor. By changing the gain of the image intensifier, both photon-counting and integrating measurements can be performed. Speckle patterns with a high signal-to-noise ratio can be observed in a single shot in the integrating mode, while XPCS measurement can be performed with much fewer photons in the photon-counting mode. By switching the image sensor, various combinations of frame rate, dynamic range and active area can be obtained. By virtue of these characteristics, this detector can be used for XPCS measurements of various types of samples that show slow or fast dynamics, a high or low scattering intensity, and a wide or narrow range of scattering angles. PMID:20975218

  3. LAMBDA — Large Area Medipix3-Based Detector Array

    NASA Astrophysics Data System (ADS)

    Pennicard, D.; Lange, S.; Smoljanin, S.; Hirsemann, H.; Graafsma, H.

    2012-11-01

    Medipix3 is a photon-counting readout chip for X-ray detection. It has a small pixel size (55 μm) and a high frame rate with zero dead time, which makes it attractive for experiments at synchrotrons. Using Medipix3, DESY are developing the LAMBDA (Large Area Medipix3-Based Detector Array) system. A single LAMBDA module carries either a single large silicon sensor of 1536 by 512 pixels, or two smaller high-Z sensors. The sensor is bonded to 12 Medipix3 chips, and mounted on a ceramic carrier board. The readout system for the module then provides a fast FPGA, a large RAM and four 10 Gigabit Ethernet links to allow operation at high frame rates. Multiple modules may then be tiled together a larger area. Currently, the first large silicon modules have been constructed and tested at low speed, and the firmware for fast readout is being developed.

  4. Readout for a large area neutron sensitive microchannel plate detector

    NASA Astrophysics Data System (ADS)

    Wang, Yiming; Yang, Yigang; Wang, Xuewu; Li, Yuanjing

    2015-06-01

    A neutron sensitive microchannel plate (MCP) detector was developed for neutron imaging on the beamline of a compact pulsed hadron source (CPHS). The detector was set up with a Wedge-and-Strip Anode (WSA) and a delay line anode readout to compare the spatial resolution and throughput with these two anodes. Tests show that the WSA readout is suitable for small area imaging with a spatial resolution of 200 μm with low energy X-rays in a 50 mm diameter MCP-WSA assembly. However, the spatial resolution deteriorated to ~2 mm in a 106 mm diameter MCP-WSA assembly because the noise caused by the parasitic capacitance is 10 times larger in the larger assembly than in the 50 mm diameter assembly. A 120 mm by 120 mm delay line anode was then used for the 106 mm MCP readout. The spatial resolution was evaluated for various voltages applied to the MCP V-stack, various readout voltages and various distances between the MCP V-stack rear face and the delay line. The delay line readout had resolutions of 65.6 μm in the x direction and 63.7 μm in the y direction and the throughput was greater than 600 kcps. The MCP was then used to acquire a neutron image of an USAF1951 Gd-mask.

  5. The lartge-area picosecond photo-detector (LAPPD) project

    NASA Astrophysics Data System (ADS)

    Varner, Gary

    2012-03-01

    The technological revolution that replaced the bulky Cathode Ray Tube with a wide variety of thin, reduced-cost display technologies, has yet to be realized for photosensors. Such a low-cost, robust and flexible photon detector, capable of efficient single photon measurement with good spatial and temporal resolution, would have numerous scientific, medical and industrial applications. To address the significant technological challenges of realizing such a disruptive technology, the Large Area Picosecond Photo-Detector (LAPPD) collaboration was formed, and has been strongly supported by the Department of Energy. This group leverages the inter-disciplinary capabilities and facilities at Argonne National Laboratory, the Berkeley Space Sciences Laboratory (SSL), electronics expertise at the Universities of Chicago and Hawaii, and close work with industrial partners to extend the known technologies. Advances in theory-inspired design and in-situ photocathode characterization during growth, Atomic Layer Deposition (ALD) for revolutionizing micro-channel plate fabrication, and compact, wave-form sampling CMOS ASIC readout of micro striplines are key tools toward realizing a viable LAPPD device. Progress toward a first 8" x 8" demonstrator module will be presented.

  6. Polycrystalline CVD diamond detector: Fast response and high sensitivity with large area

    SciTech Connect

    Liu, Linyue Zhang, Xianpeng; Zhong, Yunhong; Ouyang, Xiaoping Zhang, Jianfu

    2014-01-15

    Polycrystalline diamond was successfully used to fabricate a large area (diameter up to 46 mm) radiation detector. It was proven that the developed detector shows a fast pulsed response time and a high sensitivity, therefore its rise time is lower than 5 ns, which is two times faster than that of a Si-PIN detector of the same size. And because of the large sensitive area, this detector shows good dominance in fast pulsed and low density radiation detection.

  7. Synthesis and evaluation of phase detectors for active bit synchronizers

    NASA Technical Reports Server (NTRS)

    Mcbride, A. L.

    1974-01-01

    Self-synchronizing digital data communication systems usually use active or phase-locked loop (PLL) bit synchronizers. The three main elements of PLL synchronizers are the phase detector, loop filter, and the voltage controlled oscillator. Of these three elements, phase detector synthesis is the main source of difficulty, particularly when the received signals are demodulated square-wave signals. A phase detector synthesis technique is reviewed that provides a physically realizable design for bit synchronizer phase detectors. The development is based upon nonlinear recursive estimation methods. The phase detector portion of the algorithm is isolated and analyzed.

  8. Charged particle detectors with active detector surface for partial energy deposition of the charged particles and related methods

    DOEpatents

    Gerts, David W; Bean, Robert S; Metcalf, Richard R

    2013-02-19

    A radiation detector is disclosed. The radiation detector comprises an active detector surface configured to generate charge carriers in response to charged particles associated with incident radiation. The active detector surface is further configured with a sufficient thickness for a partial energy deposition of the charged particles to occur and permit the charged particles to pass through the active detector surface. The radiation detector further comprises a plurality of voltage leads coupled to the active detector surface. The plurality of voltage leads is configured to couple to a voltage source to generate a voltage drop across the active detector surface and to separate the charge carriers into a plurality of electrons and holes for detection. The active detector surface may comprise one or more graphene layers. Timing data between active detector surfaces may be used to determine energy of the incident radiation. Other apparatuses and methods are disclosed herein.

  9. The GLAST Large Area Telescope Detector Performance Monitoring

    SciTech Connect

    Borgland, A.W.; Charles, E.; /SLAC

    2007-10-16

    The Large Area Telescope (LAT) is one of two instruments on board the Gamma-ray Large Area Telescope (GLAST), the next generation high energy gamma-ray space telescope. The LAT contains sixteen identical towers in a four-by-four grid. Each tower contains a silicon-strip tracker and a CsI calorimeter that together will give the incident direction and energy of the pair-converting photon in the energy range 20 MeV - 300 GeV. In addition, the instrument is covered by a finely segmented Anti-Coincidence Detector (ACD) to reject charged particle background. Altogether, the LAT contains more than 864k channels in the trackers, 1536 CsI crystals and 97 ACD plastic scintillator tiles and ribbons. Here we detail some of the strategies and methods for how we are planning to monitor the instrument performance on orbit. It builds on the extensive experience gained from Integration & Test and Commissioning of the instrument on ground.

  10. A large area silicon UCN detector with the analysis of UCN polarization

    NASA Astrophysics Data System (ADS)

    Lasakov, M. S.; Serebrov, A. P.; Khusainov, A. Kh.; Pustovoit, A.; Borisov, Yu. V.; Fomin, A. K.; Geltenbort, P.; Kon'kov, O. I.; Kotina, I. M.; Shablii, A. I.; Solovei, V. A.; Vasiliev, A. V.

    2005-06-01

    A silicon UCN detector with an area of 45 cm2 and with a 6LiF converter was developed at PNPI. The spectral efficiency of the silicon UCN detector was measured by means of a gravitational spectrometer at ILL. The sandwich-type detector from two silicon plates with a 6LiF converter placed between them was also studied. Using this type of technology the UCN detector with analysis of polarization was developed and tested. The analyzing power of this detector assembly reaches up to 75% for the main part of UCN spectrum. This UCN detector with analysis of UCN polarization can be used in the new EDM spectrometer.

  11. A new active thermal neutron detector.

    PubMed

    Bedogni, R; Bortot, D; Pola, A; Introini, M V; Gentile, A; Esposito, A; Gómez-Ros, J M; Palomba, M; Grossi, A

    2014-10-01

    This communication presents the main results about the design and in-house fabrication of a new solid-state neutron detector, which produces a DC output signal proportional to the thermal neutron fluence rate. The detector has been developed within the framework of the 3-y project NESCOFI@BTF of INFN (CSN V). Due to its sensitivity, photon rejection, low cost and minimum size, this device is suited to be used in moderator-based spectrometers. PMID:24345462

  12. The design of the TASD (totally active scintillator detector) prototype

    SciTech Connect

    Mefodiev, A. V. Kudenko, Yu. G.

    2015-12-15

    Totally active and magnetic segmented scintillation neutrino detectors are developed for the nextgeneration accelerator neutrino experiments. Such detectors will incorporate scintillation modules with scintillation counters that form X and Y planes. A single counter is a 7 × 10 × 90 mm{sup 3} scintillation bar with gluedin wavelength-shifting fibers and micropixel avalanche photodiodes. The results of measurements of the parameters of these detectors are presented.

  13. Status of the development of large area photon detectors based on THGEMs and hybrid MPGD architectures for Cherenkov imaging applications

    NASA Astrophysics Data System (ADS)

    Alexeev, M.; Birsa, R.; Bradamante, F.; Bressan, A.; Büchele, M.; Chiosso, M.; Ciliberti, P.; Torre, S. Dalla; Dasgupta, S.; Denisov, O.; Duic, V.; Finger, M.; Finger, M.; Fischer, H.; Giorgi, M.; Gobbo, B.; Gregori, M.; Herrmann, F.; Königsmann, K.; Levorato, S.; Maggiora, A.; Martin, A.; Menon, G.; Steiger, K.; Novy, J.; Panzieri, D.; Pereira, F. A.; Santos, C. A.; Sbrizzai, G.; Schiavon, P.; Schopferer, S.; Slunecka, M.; Sozzi, F.; Steiger, L.; Sulc, M.; Takekawa, S.; Tessarotto, F.; Veloso, J. F. C. A.; Makke, N.

    2016-07-01

    We report about the development status of large area gaseous single photon detectors based on a novel hybrid concept for RICH applications. The hybrid concept combines Thick Gaseous Electron Multipliers (THGEMs) coupled to CsI, working as a photon sensitive pre-amplification stage, and Micromegas, as a multiplication stage. The most recent achievements within the research and development programme consist in the assembly and study of 300 × 300mm2 hybrid photon detectors, the optimization of front-end electronics, and engineering towards large area detectors. Hybrid detectors with an active area of 300 × 300mm2 have been successfully operated in laboratory conditions and at a CERN PS T10 test beam, achieving effective gains in the order of 105 and good time resolution (σ = 7 ns); APV25 front-end chips have been coupled to the detector resulting in noise levels lower than 1000 electrons; the production and characterization of 300 × 600mm2 THGEMs is ongoing. A set of hybrid detectors with 600 × 600mm2 active area is envisaged to upgrade COMPASS RICH-1 at CERN in 2016.

  14. DESIGN OF A LARGE-AREA FAST NEUTRON DIRECTIONAL DETECTOR.

    SciTech Connect

    VANIER, P.E.

    2006-10-29

    A large-area fast-neutron double-scatter directional detector and spectrometer is being constructed using l-meter-long plastic scintillator paddles with photomultiplier tubes at both ends. The scintillators detect fast neutrons by proton recoil and also gamma rays by Compton scattering. The paddles are arranged in two parallel planes so that neutrons can be distinguished from muons and gamma rays by time of flight between the planes. The signal pulses are digitized with a time resolution of one gigasample per second. The location of an event along each paddle can be determined from the relative amplitudes or timing of the signals at the ends. The angle of deflection of a neutron in the first plane can be estimated from the energy deposited by the recoil proton, combined with the scattered neutron time-of-flight energy. Each scattering angle can be back-projected as a cone, and many intersecting cones define the incident neutron direction from a distant point source. Moreover, the total energy of each neutron can be obtained, allowing some regions of a fission source spectrum to be distinguished from background generated by cosmic rays. Monte Carlo calculations will be compared with measurements.

  15. Design and feasibility of active matrix flat panel detector using avalanche amorphous selenium for protein crystallography.

    PubMed

    Sultana, Afrin; Reznik, Alla; Karim, Karim S; Rowlands, J A

    2008-10-01

    Protein crystallography is the most important technique for resolving the three-dimensional atomic structure of protein by measuring the intensity of its x-ray diffraction pattern. This work proposes a large area flat panel detector for protein crystallography based on direct conversion x-ray detection technique using avalanche amorphous selenium (a-Se) as the high gain photoconductor, and active matrix readout using amorphous silicon (a-Si:H) thin film transistors. The detector employs avalanche multiplication phenomenon of a-Se to make the detector sensitive to each incident x ray. The advantages of the proposed detector over the existing imaging plate and charge coupled device detectors are large area, high dynamic range coupled to single x-ray detection capability, fast readout, high spatial resolution, and inexpensive manufacturing process. The optimal detector design parameters (such as detector size, pixel size, and thickness of a-Se layer), and operating parameters (such as electric field across the a-Se layer) are determined based on the requirements for protein crystallography application. The performance of the detector is evaluated in terms of readout time (<1 s), dynamic range (approximately 10(5)), and sensitivity (approximately 1 x-ray photon), thus validating the detector's efficacy for protein crystallography. PMID:18975678

  16. Detector analysis for shallow water active sonar

    NASA Astrophysics Data System (ADS)

    Pastore, Thomas J.; Phillips, Michael E.

    2002-11-01

    SPAWAR Systems Center-San Diego, in concert with the Office of Naval Research (ONR) and Defense Advanced Research Projects Agency (DARPA) has designed and built a proof-of-concept broadband biomimetic sonar. This proof-of-concept sonar emulates a dolphin biosonar system; emitted broadband signals approximate the frequency and time domain characteristics of signals produced by echolocating dolphins, the receive system is spatially modeled after the binaural geometry of the dolphin, and signal processing algorithms incorporate sequential integration of aspect varying returns. As with any sonar, object detection in shallow water while maintaining an acceptable false alarm rate is an important problem. A comprehensive parametric analysis of detection algorithms is presented, focusing primarily on two detector strategies: a matched filter and a spectral detector. The spectral detector compares the ratio of in-band to out-of-band power, and thus functions something like a phase-incoherent matched filter. This computationally efficient detector is shown to perform well with high proportional bandwidth signals. The detector (either matched filter or spectral) is coupled with an alpha-beta tracker which maintains a running noise estimate and calculates signal excess above the estimated noise level which is compared to a fixed threshold.

  17. A Study of 3He detectors for Active Interrogation

    SciTech Connect

    E.H. Seabury; D.L. Chichester

    2009-10-01

    3He proportional counters have long been used as neutron detectors for both passive and active detection of Special Nuclear Material (SNM). The optimal configuration of these detectors as far as gas pressure, amount of moderating material, and size are concerned is highly dependent on what neutron signatures are being used to detect and identify SNM. We present here a parametric study of the neutron capture response of 3He detectors, based on Monte Carlo simulations using the MCNPX radiation transport code. The neutron capture response of the detectors has been modeled as a function of time after an incident neutron pulse.

  18. Cryogenic Wide-Area Light Detectors for Neutrino and Dark Matter Searches

    NASA Astrophysics Data System (ADS)

    Di Domizio, S.; Bagni, R.; Battistelli, E. S.; Bellini, F.; Bucci, C.; Calvo, M.; Cardani, L.; Castellano, M. G.; Coppolecchia, A.; Cosmelli, C.; Cruciani, A.; D'Addabbo, A.; de Bernardis, P.; Masi, S.; Pinci, D.; Vignati, M.

    2014-09-01

    Large-mass arrays of bolometers proved to be good detectors for neutrinoless double beta decay (0DBD) and dark matter searches. CUORE and LUCIFER are bolometric 0DBD experiments that will start to take data in 2015 at Laboratori Nazionali del Gran Sasso in Italy. The sensitivity of CUORE could be increased by removing the background due to particles, by detecting the small amount of Čerenkov light (100 eV) emitted by the s' signal and not by s. LUCIFER could be extended to detect also dark matter, provided that the background from / particles (100 eV of scintillation light) is discriminated from nuclear recoils of about 10 keV energy (no light). We have recently started to develop light detectors for CUORE, LUCIFER and similar bolometric experiments. The aim is to obtain detectors with an active area of (the face of bolometric crystals), operating at 10 mK, and with an energy resolution at the baseline below 20 eV RMS. We have chosen to develop phonon-mediated detectors with KID sensors. We are currently testing the first prototypes.

  19. Large-area solid state detector for radiology using amorphous selenium

    NASA Astrophysics Data System (ADS)

    Zhao, Wei; Rowlands, John A.

    1992-06-01

    A large area self-scanned solid-state detector is being developed for digital radiology. It consists of an x-ray sensitive flat-panel employing amorphous selenium ((alpha) )-Se) as the x- ray transducer and active matrix integrated circuit for readout. In principle such detectors could be used for all the currently applied radiological modalities -- radiography, photofluorography, and fluoroscopy. Layers of (alpha) )-Se up to 500 micrometers thick are readout with an array of thin film field effect transistors. The whole structure is integrated onto a glass plate. For all practical purposes the resolution of the system is dictated by the pixel size and readout could be in real-time (i.e., 30 frames/sec).

  20. Infrared Detector Activities at NASA Langley Research Center

    NASA Technical Reports Server (NTRS)

    Abedin, M. N.; Refaat, T. F.; Sulima, O. V.; Amzajerdian, F.

    2008-01-01

    Infrared detector development and characterization at NASA Langley Research Center will be reviewed. These detectors were intended for ground, airborne, and space borne remote sensing applications. Discussion will be focused on recently developed single-element infrared detector and future development of near-infrared focal plane arrays (FPA). The FPA will be applied to next generation space-based instruments. These activities are based on phototransistor and avalanche photodiode technologies, which offer high internal gain and relatively low noise-equivalent-power. These novel devices will improve the sensitivity of active remote sensing instruments while eliminating the need for a high power laser transmitter.

  1. Comparison of activation effects in {gamma}-ray detector materials

    SciTech Connect

    Truscott, P.R.; Evans, H.E.; Dyer, C.S.; Peerless, C.L.; Flatman, J.C.; Cosby, M.; Knight, P.; Moss, C.E.

    1996-06-01

    Activation induced by cosmic and trapped radiation in {gamma}-ray detector materials represents a significant source of background for space-based detector systems. Selection of detector materials should therefore include consideration of this background source. Results are presented from measurements of induced radioactivity in different scintillators activated either as a result of irradiation by mono-energetic protons at accelerator facilities, or flight on board the Space Shuttle. Radiation transport computer codes are used to help compare the effects observed from the scintillators, by identifying and quantifying the influence on the background spectra from more than one hundred of the radionuclides produced by spallation. For the space experiment data, the simulation results also permit determination of the contributions to detector activation from the different sources of radiation in the Shuttle cabin.

  2. Active Well Counting Using New PSD Plastic Detectors

    SciTech Connect

    Hausladen, Paul; Newby, Jason; McElroy, Robert Dennis

    2015-11-01

    This report presents results and analysis from a series of proof-of-concept measurements to assess the suitability of segmented detectors constructed from Eljen EJ-299-34 PSD-plastic scintillator with pulse-shape discrimination capability for the purposes of quantifying uranium via active neutron coincidence counting. Present quantification of bulk uranium materials for international safeguards and domestic materials control and accounting relies on active neutron coincidence counting systems, such as the Active Well Coincidence Counter (AWCC) and the Uranium Neutron Coincidence Collar (UNCL), that use moderated He-3 proportional counters along with necessarily low-intensity 241Am(Li) neutron sources. Scintillation-based fast-neutron detectors are a potentially superior technology to the existing AWCC and UNCL designs due to their spectroscopic capability and their inherently short neutron coincidence times that largely eliminate random coincidences and enable interrogation by stronger sources. One of the past impediments to the investigation and adoption of scintillation counters for the purpose of quantifying bulk uranium was the commercial availability of scintillators having the necessary neutron-gamma pulse-shape discrimination properties only as flammable liquids. Recently, Eljen EJ-299-34 PSD-plastic scintillator became commercially available. The present work is the first assessment of an array of PSD-plastic detectors for the purposes of quantifying bulk uranium. The detector panel used in the present work was originally built as the focal plane for a fast-neutron imager, but it was repurposed for the present investigation by construction of a stand to support the inner well of an AWCC immediately in front of the detector panel. The detector panel and data acquisition of this system are particularly well suited for performing active-well fast-neutron counting of LEU and HEU samples because the active detector volume is solid, the 241Am(Li) interrogating

  3. Large area radiation detectors based on II VI thin films

    NASA Astrophysics Data System (ADS)

    Quevedo-Lopez, Manuel

    2015-03-01

    The development of low temperature device technologies that have enabled flexible displays also present opportunities for flexible electronics and flexible integrated systems. Of particular interest are possible applications in flexible, low metal content, sensor systems for unattended ground sensors, smart medical bandages, electronic ID tags for geo-location, conformal antennas, neutron/gamma-ray/x-ray detectors, etc. In this talk, our efforts to develop novel CMOS integration schemes, circuits, memory, sensors as well as novel contacts, dielectrics and semiconductors for flexible electronics are presented. In particular, in this presentation we discuss fundamental materials properties including crystalline structure, interfacial reactions, doping, etc. defining performance and reliability of II-VI-based radiation sensors. We investigate the optimal thickness of a semiconductor diode for thin-film solid state thermal neutron detectors. Besides II-VI materials, we also evaluated several diode materials, Si, CdTe,GaAs, C (diamond), and ZnO, and two neutron converter materials,10B and 6LiF. We determine the minimum semiconductor thickness needed to achieve maximum neutron detection efficiency. By keeping the semiconductor thickness to a minimum, gamma rejection is kept as high as possible. In this way, we optimize detector performance for different thin-film semiconductor materials.

  4. A Silicon UCN Detector With Large Area and With Analysis of UCN Polarization.

    PubMed

    Lasakov, M; Serebrov, A; Khusainov, A; Pustovoit, A; Borisov, Yu; Fomin, A; Geltenbort, P; Kon'kov, O; Kotina, I; Shablii, A; Solovei, V; Vasiliev, A

    2005-01-01

    A silicon ultracold neutron (UCN) detector with an area of 45 cm(2) and with a (6)LiF converter is developed at St. Petersburg Nuclear Physics Institute (PNPI). The spectral efficiency of the silicon UCN detector was measured by means of a gravitational spectrometer at Institut Max von Laue - Paul Langevin (ILL). The sandwich-type detector from two silicon plates with a (6)LiF converter placed between them was also studied. Using this type of technology the UCN detector with analysis of polarization was developed and tested. The analyzing power of this detector assembly reaches up 75 % for the main part of UCN spectrum. This UCN detector with analysis of UCN polarization can be used in the new electric dipole moment (EDM) spectrometer. PMID:27308138

  5. A Silicon UCN Detector With Large Area and With Analysis of UCN Polarization

    PubMed Central

    Lasakov, M.; Serebrov, A.; Khusainov, A.; Pustovoit, A.; Borisov, Yu.; Fomin, A.; Geltenbort, P.; Kon’kov, O.; Kotina, I.; Shablii, A.; Solovei, V.; Vasiliev, A.

    2005-01-01

    A silicon ultracold neutron (UCN) detector with an area of 45 cm2 and with a 6LiF converter is developed at St. Petersburg Nuclear Physics Institute (PNPI). The spectral efficiency of the silicon UCN detector was measured by means of a gravitational spectrometer at Institut Max von Laue – Paul Langevin (ILL). The sandwich-type detector from two silicon plates with a 6LiF converter placed between them was also studied. Using this type of technology the UCN detector with analysis of polarization was developed and tested. The analyzing power of this detector assembly reaches up 75 % for the main part of UCN spectrum. This UCN detector with analysis of UCN polarization can be used in the new electric dipole moment (EDM) spectrometer. PMID:27308138

  6. Monolithic active pixel radiation detector with shielding techniques

    DOEpatents

    Deptuch, Grzegorz W.

    2016-09-06

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

  7. Area x-ray detector based on a lens-coupled charge-coupled device

    SciTech Connect

    Tate, Mark W.; Chamberlain, Darol; Gruner, Sol M.

    2005-08-15

    An area x-ray detector constructed using commercially available 'off-the-shelf' parts is described and its performance is characterized. The detector consists of a 1024x1024 pixel charge-coupled device (CCD) camera optically coupled to x-ray sensitive phosphor screen using a standard 35 mm camera lens. The conversion efficiency, spatial nonuniformity, spatial resolution and the detective quantum efficiency of the detector have been measured. Also shown is an example of data taken with the detector. The detector is a relatively low-cost device suitable for a wide variety of quantitative x-ray experiments where the input area need not be larger than about 70 mm across.

  8. A large area, silicon photomultiplier-based PET detector module

    PubMed Central

    Raylman, RR; Stolin, A; Majewski, S; Proffitt, J

    2013-01-01

    The introduction of silicon photomultipliers (SiPM) has facilitated construction of compact, efficient and magnetic field-hardened positron emission tomography (PET) scanners. To take full advantage of these devices, methods for using them to produce large field-of-view PET scanners are needed. In this investigation, we explored techniques to combine two SiPM arrays to form the building block for a small animal PET scanner. The module consists of a 26 × 58 array of 1.5 × 1.5mm2 LYSO elements (spanning 41 × 91mm2) coupled to two SensL SiPM arrays. The SiPMs were read out with new multiplexing electronics developed for this project. To facilitate calculation of event position with multiple SiPM arrays it was necessary to spread scintillation light amongst a number of elements with a small light guide. This method was successful in permitting identification of all detector elements, even at the seam between two SiPM arrays. Since the performance of SiPMs is enhanced by cooling, the detector module was fitted with a cooling jacket, which allowed the temperature of the device and electronics to be controlled. Testing demonstrated that the peak-to-valley contrast ratio of the light detected from the scintillation array was increased by ∼45% when the temperature was reduced from 28 °C to 16 °C. Energy resolution for 511 keV photons improved slightly from 18.8% at 28 °C to 17.8% at 16 °C. Finally, the coincidence timing resolution of the module was found to be insufficient for time-of-flight applications (∼2100 ps at 14 °C). The first use of these new modules will be in the construction of a small animal PET scanner to be integrated with a 3T clinical magnetic resonance imaging scanner. PMID:24319305

  9. A large area, silicon photomultiplier-based PET detector module

    NASA Astrophysics Data System (ADS)

    Raylman, R. R.; Stolin, A.; Majewski, S.; Proffitt, J.

    2014-01-01

    The introduction of silicon photomultipliers (SiPM) has facilitated construction of compact, efficient and magnetic field-hardened positron emission tomography (PET) scanners. To take full advantage of these devices, methods for using them to produce large field-of-view PET scanners are needed. In this investigation, we explored techniques to combine two SiPM arrays to form the building block for a small animal PET scanner. The module consists of a 26×58 array of 1.5×1.5 mm2 LYSO elements (spanning 41×91 mm2) coupled to two SensL SiPM arrays. The SiPMs were read out with new multiplexing electronics developed for this project. To facilitate calculation of event position with multiple SiPM arrays it was necessary to spread scintillation light amongst a number of elements with a small light guide. This method was successful in permitting identification of all detector elements, even at the seam between two SiPM arrays. Since the performance of SiPMs is enhanced by cooling, the detector module was fitted with a cooling jacket, which allowed the temperature of the device and electronics to be controlled. Testing demonstrated that the peak-to-valley contrast ratio of the light detected from the scintillation array was increased by ~45% when the temperature was reduced from 28 °C to 16 °C. Energy resolution for 511 keV photons improved slightly from 18.8% at 28 °C to 17.8% at 16 °C. Finally, the coincidence timing resolution of the module was found to be insufficient for time-of-flight applications (~2100 ps at 14 °C). The first use of these new modules will be in the construction of a small animal PET scanner to be integrated with a 3 T clinical magnetic resonance imaging scanner.

  10. Performance of low-cost X-ray area detectors with consumer digital cameras

    NASA Astrophysics Data System (ADS)

    Panna, A.; Gomella, A. A.; Harmon, K. J.; Chen, P.; Miao, H.; Bennett, E. E.; Wen, H.

    2015-05-01

    We constructed X-ray detectors using consumer-grade digital cameras coupled to commercial X-ray phosphors. Several detector configurations were tested against the Varian PaxScan 3024M (Varian 3024M) digital flat panel detector. These include consumer cameras (Nikon D800, Nikon D700, and Nikon D3X) coupled to a green emission phosphor in a back-lit, normal incidence geometry, and in a front-lit, oblique incidence geometry. We used the photon transfer method to evaluate detector sensitivity and dark noise, and the edge test method to evaluate their spatial resolution. The essential specifications provided by our evaluation include discrete charge events captured per mm2 per unit exposure surface dose, dark noise in equivalents of charge events per pixel, and spatial resolution in terms of the full width at half maximum (FWHM) of the detector`s line spread function (LSF). Measurements were performed using a tungsten anode X-ray tube at 50 kVp. The results show that the home-built detectors provide better sensitivity and lower noise than the commercial flat panel detector, and some have better spatial resolution. The trade-off is substantially smaller imaging areas. Given their much lower costs, these home-built detectors are attractive options for prototype development of low-dose imaging applications.

  11. Optical theorem detectors for active scatterers

    NASA Astrophysics Data System (ADS)

    Marengo, Edwin A.; Tu, Jing

    2015-10-01

    We develop a new theory of the optical theorem for scalar fields in nonhomogeneous media which can be bounded or unbounded. It applies to arbitrary lossless backgrounds and quite general probing fields. The derived formulation holds for arbitrary passive scatterers, which can be dissipative, as well as for the more general class of active scatterers which are composed of a (passive) scatterer component and an active, radiating (antenna) component. The generalization of the optical theorem to active scatterers is relevant to many applications such as surveillance of active targets including certain cloaks and invisible scatterers and wireless communications. The derived theoretical framework includes the familiar real power optical theorem describing power extinction due to both dissipation and scattering as well as a novel reactive optical theorem related to the reactive power changes. The developed approach naturally leads to three optical theorem indicators or statistics which can be used to detect changes or targets in unknown complex media. The paper includes numerical simulation results that illustrate the application of the derived optical theorem results to change detection in complex and random media.

  12. Early detectors of the heart's electrical activity.

    PubMed

    Breathnach, Caoimhghín S; Westphal, Wolfgang

    2006-04-01

    It was in Matteucci's rheoscopic frog in Pisa that evidence was first found for the electrical activity of the heart in 1844, and his results were confirmed and expanded 12 years later at Würzburg. The capillary electrometer gave a continuous record that could be photographed, and was used initially by Einthoven who, to obviate the onerous mathematical conversion of the electrometer record, developed the string galvanometer by the close of the century, and showed its clinical value in 1906. PMID:16650272

  13. Detectors

    DOEpatents

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

    2002-01-01

    The apparatus and method provide techniques through which both alpha and beta emission determinations can be made simultaneously using a simple detector structure. The technique uses a beta detector covered in an electrically conducting material, the electrically conducting material discharging ions generated by alpha emissions, and as a consequence providing a measure of those alpha emissions. The technique also offers improved mountings for alpha detectors and other forms of detectors against vibration and the consequential effects vibration has on measurement accuracy.

  14. Thin film cadmium telluride charged particle sensors for large area neutron detectors

    SciTech Connect

    Murphy, J. W.; Smith, L.; Calkins, J.; Mejia, I.; Cantley, K. D.; Chapman, R. A.; Quevedo-Lopez, M.; Gnade, B.; Kunnen, G. R.; Allee, D. R.; Sastré-Hernández, J.; Contreras-Puente, G.; Mendoza-Pérez, R.

    2014-09-15

    Thin film semiconductor neutron detectors are an attractive candidate to replace {sup 3}He neutron detectors, due to the possibility of low cost manufacturing and the potential for large areas. Polycrystalline CdTe is found to be an excellent material for thin film charged particle detectors—an integral component of a thin film neutron detector. The devices presented here are characterized in terms of their response to alpha and gamma radiation. Individual alpha particles are detected with an intrinsic efficiency of >80%, while the devices are largely insensitive to gamma rays, which is desirable so that the detector does not give false positive counts from gamma rays. The capacitance-voltage behavior of the devices is studied and correlated to the response due to alpha radiation. When coupled with a boron-based neutron converting material, the CdTe detectors are capable of detecting thermal neutrons.

  15. ACTIV: Sandwich Detector Activity from In-Pile Slowing-Down Spectra Experiment

    2013-08-01

    ACTIV calculates the activities of a sandwich detector, to be used for in-pile measurements in slowing-down spectra below a few keV. The effect of scattering with energy degradation in the filter and in the detectors has been included to a first approximation.

  16. NaI detector neutron activation spectra for PGNAA applications

    PubMed

    Gardner; El; Zheng; Hayden; Mayo

    2000-10-01

    When NaI detectors are used in prompt gamma-ray neutron activation analysis devices, they are activated by neutrons that penetrate the detector. While thermal neutron filters like boron or lithium can be used to reduce this activation, it can never be completely eliminated by this approach since high energy neutrons can penetrate the detector and thermalize inside it. This activation results in the emission of prompt gamma rays from both the I and Na and the production of the radioisotopes 128I and 24Na that subsequently decay and emit their characteristic beta particles and gamma rays. The resulting three spectra represent a background for this measurement. An experimental method for obtaining these three spectra is described and results are reported for 2" x 2", 5" x 5", 6" x 6", and 1" x 6" NaI detectors using the thermal neutron beam of the NCSU PULSTAR nuclear reactor. In addition, Monte Carlo simulation programs have been developed and used for simulating these spectra. Good results have been obtained by the Monte Carlo method for the two radioisotope spectra, and it is anticipated that good results will also be obtained for the prompt gamma-ray spectrum when the I and Na coincidence schemes are known. PMID:11003483

  17. Physical characterization and performance comparison of active- and passive-pixel CMOS detectors for mammography.

    PubMed

    Elbakri, I A; McIntosh, B J; Rickey, D W

    2009-03-21

    We investigated the physical characteristics of two complementary metal oxide semiconductor (CMOS) mammography detectors. The detectors featured 14-bit image acquisition, 50 microm detector element (del) size and an active area of 5 cm x 5 cm. One detector was a passive-pixel sensor (PPS) with signal amplification performed by an array of amplifiers connected to dels via data lines. The other detector was an active-pixel sensor (APS) with signal amplification performed at each del. Passive-pixel designs have higher read noise due to data line capacitance, and the APS represents an attempt to improve the noise performance of this technology. We evaluated the detectors' resolution by measuring the modulation transfer function (MTF) using a tilted edge. We measured the noise power spectra (NPS) and detective quantum efficiencies (DQE) using mammographic beam conditions specified by the IEC 62220-1-2 standard. Our measurements showed the APS to have much higher gain, slightly higher MTF, and higher NPS. The MTF of both sensors approached 10% near the Nyquist limit. DQE values near dc frequency were in the range of 55-67%, with the APS sensor DQE lower than the PPS DQE for all frequencies. Our results show that lower read noise specifications in this case do not translate into gains in the imaging performance of the sensor. We postulate that the lower fill factor of the APS is a possible cause for this result. PMID:19242050

  18. Results of testing the energy dispersive Si detector with large working area

    NASA Astrophysics Data System (ADS)

    Gogolev, A. S.; Hampai, D.; Khusainov, A. Kh.; Zhukov, M. P.; Dabagov, S. B.; Potylitsyn, A. P.; Liedl, A.; Polese, C.

    2015-07-01

    In this work the testing results for the spectrometer with a large sensitive area developed for the crystal monitoring station of modern hadron accelerator control systems used for the beam collimation are presented. The investigations were carried out at the XLab Frascati LNF laboratory aiming mostly in studying the detector sensitivity uniformity throughout the sensor area.

  19. Large area nuclear particle detectors using ET materials

    NASA Technical Reports Server (NTRS)

    1987-01-01

    The purpose of this SBIR Phase 1 feasibility effort was to demonstrate the usefulness of Quantex electron-trapping (ET) materials for spatial detection of nuclear particles over large areas. This demonstration entailed evaluating the prompt visible scintillation as nuclear particles impinged on films of ET materials, and subsequently detecting the nuclear particle impingement information pattern stored in the ET material, by means of the visible-wavelength luminescence produced by near-infrared interrogation. Readily useful levels of scintillation and luminescence outputs are demonstrated.

  20. Tests of innovative photon detectors and integrated electronics for the large-area CLAS12 ring-imaging Cherenkov detector

    NASA Astrophysics Data System (ADS)

    Contalbrigo, M.

    2015-07-01

    A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capability in the momentum range from 3 GeV/c to 8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron beam accelerator facility of Jefferson Lab. Its aim is to study the 3D nucleon structure in the yet poorly explored valence region by deep-inelastic scattering, and to perform precision measurements in hadron spectroscopy. The adopted solution foresees a novel hybrid optics design based on an aerogel radiator, composite mirrors and a densely packed and highly segmented photon detector. Cherenkov light will either be imaged directly (forward tracks) or after two mirror reflections (large angle tracks). Extensive tests have been performed on Hamamatsu H8500 and novel flat multi-anode photomultipliers under development and on various types of silicon photomultipliers. A large scale prototype based on 28 H8500 MA-PMTs has been realized and tested with few GeV/c hadron beams at the T9 test-beam facility of CERN. In addition a small prototype was used to study the response of customized SiPM matrices within a temperature interval ranging from 25 down to -25 °C. The preliminary results of the individual photon detector tests and of the prototype performance at the test-beams are here reported.

  1. Tests of innovative photon detectors and integrated electronics for the large-area CLAS12 ring-imaging Cherenkov detector

    SciTech Connect

    Contalbrigo, Marco

    2015-07-01

    A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capability in the momentum range from 3 GeV/c to 8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron beam accelerator facility of Jefferson Lab. Its aim is to study the 3D nucleon structure in the yet poorly explored valence region by deep-inelastic scattering, and to perform precision measurements in hadron spectroscopy. The adopted solution foresees a novel hybrid optics design based on an aerogel radiator, composite mirrors and a densely packed and highly segmented photon detector. Cherenkov light will either be imaged directly (forward tracks) or after two mirror reflections (large angle tracks). Extensive tests have been performed on Hamamatsu H8500 and novel flat multi-anode photomultipliers under development and on various types of silicon photomultipliers. A large scale prototype based on 28 H8500 MA-PMTs has been realized and tested with few GeV/c hadron beams at the T9 test-beam facility of CERN. In addition a small prototype was used to study the response of customized SiPM matrices within a temperature interval ranging from 25 down to –25 °C. The preliminary results of the individual photon detector tests and of the prototype performance at the test-beams are here reported.

  2. Noise in large-area CrlS Hg1-xCdxTe photovoltaic detectors

    NASA Astrophysics Data System (ADS)

    D'Souza, Arvind I.; Stapelbroek, Maryn G.; Masterjohn, Stacy A.; Wijewarnasuriya, Priyalal S.; DeWames, Roger E.; Smith, David S.; Ehlert, John C.

    2003-01-01

    The National Polar-orbiting Operational Environmental Satellite System (NPOESS) Cross-track Infrared Sounder (CrIS) is a Fourier Transform interferometric sensor that measures earth radiances at high spectral resolution. Algorithms use the data to provide pressure, temperature, and moisture profiles of the atmosphere. The CrIS instrument contains photovoltaic detectors with spectral cut-offs denoted by SWIR, MWIR and LWIR. The CrIS instrument requires large-area, photovoltaic detectors with state-of-art detector performance at temperatures attainable with passive cooling. For example, detectors as large as 1 mm in diameter are required. To address these needs, Molecular Beam Epitaxy (MBE) is used to grow the appropriate bandgap n-type Hg1-xCdxTe on lattice matched CdZnTe. The p-side is obtained via arsenic implantation followed by appropriate annealing steps.

  3. New area detector for atomic-resolution scanning transmission electron microscopy.

    PubMed

    Shibata, Naoya; Kohno, Yuji; Findlay, Scott D; Sawada, Hidetaka; Kondo, Yukihito; Ikuhara, Yuichi

    2010-01-01

    A new area detector for atomic-resolution scanning transmission electron microscopy (STEM) is developed and tested. The circular detector is divided into 16 segments which are individually optically coupled with photomultiplier tubes. Thus, 16 atomic-resolution STEM images which are sensitive to the spatial distribution of scattered electrons on the detector plane can be simultaneously obtained. This new detector can be potentially used not only for the simultaneous formation of common bright-field, low-angle annular dark-field and high-angle annular dark-field images, but also for the quantification of images by detecting the full range of scattered electrons and even for exploring novel atomic-resolution imaging modes by post-processing combination of the individual images. PMID:20406732

  4. A large area cooled-CCD detector for electron microscopy

    NASA Astrophysics Data System (ADS)

    Faruqi, A. R.; Andrews, H. N.; Raeburn, C.

    1994-09-01

    Large area cooled-CCDs are an excellent medium for (indirectly) recording electron images and electron diffraction patterns in real time and for use in electron tomography; real-time imaging is extremely useful in making rapid adjustments in the electron microscope. CCDs provide high sensitivity (useful for minimising dosage to radiation-sensitive biological specimen), good resolution, stable performance, excellent dynamic range and linearity and a reasonably fast readout. We have built an electron imaging device based on the EEV 1152 by 814 pixel CCD which is controlled from a unix based SUN Sparestation operating under X-Windows. The incident 100 kV electrons are converted to visible light in a 0.5 mm thick YAG single crystal which is imaged through a lens on to the CCD. The CCD electronics is designed to be as flexible as possible and allows a wide variation in the readout speed to cater for the relatively fast application where readout noise is less critical and low readout noise applications where the extra few seconds of readout time are not significant. The CCD electronics is built in VME format which is controlled through a S-bus to VME driver. With two parallel channels of readout the whole image can be read out in ˜ 1 s (using the faster readout speed) with 16 bit precision and the image is displayed under X-Windows in a few seconds. The present readout works at 500 kHz and has a noise of ˜ 30 e rms per pixel. With a Peltier cooling device we can operate the CCD at ˜ -40°C which reduces the dark current adequately to allow exposures of up to several minutes. Several examples of patterns collected with the system on a Philips CM12 microscope will be presented.

  5. Large area space qualified thermoelectrically (TE) cooled HgCdTe MW photovoltaic detectors for the Halogen Occultation Experiment (HALOE)

    NASA Technical Reports Server (NTRS)

    Norton, P. W.; Zimmermann, P. H.; Briggs, R. J.; Hartle, N. M.

    1986-01-01

    Large-area, HgCdTe MW photovoltaic detectors have been developed for the NASA-HALOE instrument scheduled for operation on the Upper Atmospheric Research Satellite. The photodiodes will be TE-cooled and were designed to operate in the 5.1-5.4 micron band at 185 K to measure nitric oxide concentrations in the atmosphere. The active area required 15 micron thick devices and a full backside common contact. Reflections from the backside contact doubled the effective thickness of the detectors. Optical interference from reflections was eliminated with a dual layer front surface A/R coating. Bakeout reliability was optimized by having Au metallization for both n and p interconnects. Detailed performance data and a model for the optical stack are presented.

  6. Processing and characterization of edgeless radiation detectors for large area detection

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  7. Development of an array of cooled large area Si(Li) detectors

    SciTech Connect

    Pehl, R.H.; Madden, N.W.; Walton, J.T.; Malone, D.F.; Landis, D.A.; Goulding, F.S.; Cork, C.P.; Wong, Y.K.; Strauss, M.G.; Sherman, I.S.

    1985-10-01

    A system containing six cooled, 34 mm diam by 7 mm thick, high-resolution Si(Li) detectors designed to maximize the sensitivity for counting x rays in the 10-30 keV range to measure trace radionuclides in soil samples has been successfully fabricated. The detectors were mounted in a paddle-shaped cryostat with a single large beryllium window on each side. This configuration provides for efficient anticoincidence background suppression and effectively doubles the sensitive detector area because x rays can impinge on the detectors from both sides. To maximize detection efficiency, the thickness of the cryostat was held to a bare minimum (25 mm); this caused severe difficulties during fabrication of the system. Cutting down the rim of the detectors reduced to an acceptable level the microphony caused by movement of the beryllium window that faces the lithium-diffused contact of the detectors. Since this system will be used for low level counting. careful testing was performed to select materials having the lowest radioactivity.

  8. POLARCALC: A program for calculating the linear-polarization factor using an area detector

    SciTech Connect

    Molodenskii, D. S.; Sul’yanov, S. N.

    2015-05-15

    A graphical interface program has been developed to determine the linear-polarization factor of a monochromatic X-ray beam when analyzing scattering from an amorphous object. An area coordinate detector is used in measurements. The change in intensity over the azimuthal angle at a constant diffraction angle is interpolated by a theoretical cosine dependence, which contains the polarization factor.

  9. CVD diamond wafers as large-area thermoluminescence detectors for measuring the spatial distribution of dose

    NASA Astrophysics Data System (ADS)

    Marczewska, B.; Bilski, P.; Olko, P.; Olko, P.; Nesládek, M.; Bergonzo, P.; Rbisz, M.; Waligórski, M. P. R.

    2003-09-01

    The applicability of large-area CVD diamond wafers (diameter about 5 cm, thickness about 0.1 mm), read out as thermoluminescence (TL) detectors, for assessing two-dimensional (2-D) dose distribution over their area, was investigated. To obtain 2-D TL images, a special TL reader equipped with large-area planchet and a CCD camera instead of the usual PM tube was developed. Several 2-D TL images: of an alpha source (Am-241), a Ra-226 needle source and a Ru-106 ophthalmic applicator, were measured and high-resolution digital images obtained. Our preliminary results demonstrate the potential capability of large-area CVD diamond wafers, read out as TL detectors, in 2-D dosimetry for medical applications. (

  10. Novel Large Area High Resolution Neutron Detector for the Spallation Neutron Source

    SciTech Connect

    Lacy, Jeffrey L

    2009-05-22

    Neutron scattering is a powerful technique that is critically important for materials science and structural biology applications. The knowledge gained from past developments has resulted in far-reaching advances in engineering, pharmaceutical and biotechnology industries, to name a few. New facilities for neutron generation at much higher flux, such as the SNS at Oak Ridge, TN, will greatly enhance the capabilities of neutron scattering, with benefits that extend to many fields and include, for example, development of improved drug therapies and materials that are stronger, longer-lasting, and more impact-resistant. In order to fully realize this enhanced potential, however, higher neutron rates must be met with improved detection capabilities, particularly higher count rate capability in large size detectors, while maintaining practicality. We have developed a neutron detector with the technical and economic advantages to accomplish this goal. This new detector has a large sensitive area, offers 3D spatial resolution, high sensitivity and high count rate capability, and it is economical and practical to produce. The proposed detector technology is based on B-10 thin film conversion of neutrons in long straw-like gas detectors. A stack of many such detectors, each 1 meter in length, and 4 mm in diameter, has a stopping power that exceeds that of He-3 gas, contained at practical pressures within an area detector. With simple electronic readout methods, straw detector arrays can provide spatial resolution of 4 mm FWHM or better, and since an array detector of such form consists of several thousand individual elements per square meter, count rates in a 1 m^2 detector can reach 2?10^7 cps. Moreover, each individual event can be timetagged with a time resolution of less than 0.1 ?sec, allowing accurate identification of neutron energy by time of flight. Considering basic elemental cost, this novel neutron imaging detector can be commercially produced economically

  11. Area detector corrections for high quality synchrotron X-ray structure factor measurements

    SciTech Connect

    Skinner L. B.; Parise J.; Benmore, C.

    2011-10-01

    Correction procedures for obtaining accurate X-ray structure factors from large area detectors are considered, including subpanel effects, over excited pixels and careful intensity corrections. Problems associated with data normalization, the use of a pixel response correction from a glass standard and minimization of systematic errors are also discussed. Data from glassy GeSe{sub 2} and liquid water measured with a Perkin Elmer amorphous-Silicon detector are used to demonstrate the effectiveness of these correction procedures. This requires reduction of systematic errors in the measured intensity to around the 0.1% level.

  12. Design and Characteristics of the Anticoincidence Detector for the GLAST Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Moiseev, A. A.; Hartman, R. C.; Johnson, T. E.; Ormes, J. F.; Thompson, D. J.

    2005-01-01

    The Anti-Coincidence Detector (ACD) is the outermost detector layer in the GLAST Large Area Telescope (LAT), surrounding the top and sides of the tracker. The purpose of the ACD is to detect and veto incident cosmic ray charged particles, which outnumber cosmic gamma rays by 3-4 orders of magnitude. The challenge in ACD design is that it must have high (0.9997) detection efficiency for singly charged relativistic particles, but must also have low sensitivity to backsplash particles. These are products of high- energy interactions in the LAT calorimeter. They can cause a veto signal in the ACD, resulting in loss of good gamma-ray events.

  13. Large area event counting detectors with high spatial and temporal resolution

    NASA Astrophysics Data System (ADS)

    Siegmund, O. H. W.; McPhate, J. B.; Vallerga, J. V.; Tremsin, A. S.; Frisch, H. E.; Elam, J. W.; Mane, A. U.; Wagner, R. G.

    2014-04-01

    Novel large area microchannel plates (MCPs) constructed using micro-capillary arrays functionalized by atomic layer deposition (ALD) have been successfully demonstrated in large format detectors (10 cm and 20 cm) with cross delay line and cross strip readouts. Borosilicate micro-capillary substrates allow robust MCPs to be made in sizes to 20 cm, the intrinsic background rates are low ( < 0.06 events cm-2 sec-1), the channel open area can be made as high as 85%, and the gain after preconditioning (vacuum bake and burn-in) shows virtually no change over > 7 C cm-2 extracted charge. We have constructed a number of detectors with these novel MCPs, including a 10 × 10 cm cross strip readout device and 20 × 20 cm delay line readout sensors. The cross strip detector has very high spatial resolution (the 20 μm MCP pores can be resolved, thus obtaining ~ 5k × 5k resolution elements), good time resolution ( < 1 ns), and high event rate ( > 5 million counts/s at 20% dead time), while operating at relatively low gain ( ~ 106). The 20 × 20 cm delay line detectors have achieved spatial resolutions of ~ 50 μm and event rates of several MHz, with good gain and background uniformity and < 200 ps event time tagging. Progress has also been made in construction of a 20 × 20 cm sealed tube optical imager, and we have achieved > 20% quantum efficiency and good uniformity for large area (20 cm) bialkali photocathodes.

  14. Acquisition and tracking performance measurements for a high speed area array detector system

    NASA Technical Reports Server (NTRS)

    Short, R. C.; Cosgrove, M.; Clark, D. L.; Martino, A.; Park, H.; Seery, B.

    1991-01-01

    A proof-of-concept (POC) demonstration system has been developed which demonstrates acquisition, tracking and point-ahead angle sensing for a space optical communications terminal utilizing a single high speed area array detector. The detector is the 128 x 128 pixel Kodak HS-40 photodiode array. It has 64 parallel readout channels and can operate at frames rates up to 40,000 frames/sec with rms readout noise of 20 photoelectrons. A windowing scheme and special purpose digital signal processing electronics are employed to implement acquisition and tracking algorithms. The system operates at greater than 1 kHz sample (frame) rates. Acquisition can be performed in as little as 30 milliseconds with less than 1 picowatt of 0.85 micron beacon power on the detector. At the same power level, the rms tracking accuracy is approximately 1/16 pixel. Results of system analysis and measurements using the POC system are presented.

  15. The large-area hybrid-optics CLAS12 RICH detector: Tests of innovative components

    SciTech Connect

    Contalbrigo, M; Baltzell, N; Benmokhtar, F; Barion, L; Cisbani, E; El Alaoui, A; Hafidi, K; Hoek, M; Kubarovsky, V; Lagamba, L; Lucherini, V; Malaguti, R; Mirazita, M; Montgomery, R; Movsisyan, A; Musico, P; Orecchini, D; Orlandi, A; Pappalardo, L L; Pereira, S; Perrino, R; Phillips, J; Pisano, S; Rossi, P; Squerzanti, S; Tomassini, S; Turisini, M; Viticchiè, A

    2014-07-01

    A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capability in the momentum range from 3 GeV/c to 8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron beam accelerator facility of Jefferson Lab to study the 3D nucleon structure in the yet poorly explored valence region by deep-inelastic scattering, and to perform precision measurements in hadronization and hadron spectroscopy. The adopted solution foresees a novel hybrid optics design based on an aerogel radiator, composite mirrors and densely packed and highly segmented photon detectors. Cherenkov light will either be imaged directly (forward tracks) or after two mirror reflections (large angle tracks). The preliminary results of individual detector component tests and of the prototype performance at test-beams are reported here.

  16. The large-area hybrid-optics CLAS12 RICH detector: Tests of innovative components

    NASA Astrophysics Data System (ADS)

    Contalbrigo, M.; Baltzell, N.; Benmokhtar, F.; Barion, L.; Cisbani, E.; El Alaoui, A.; Hafidi, K.; Hoek, M.; Kubarovsky, V.; Lagamba, L.; Lucherini, V.; Malaguti, R.; Mirazita, M.; Montgomery, R.; Movsisyan, A.; Musico, P.; Orecchini, D.; Orlandi, A.; Pappalardo, L. L.; Pereira, S.; Perrino, R.; Phillips, J.; Pisano, S.; Rossi, P.; Squerzanti, S.; Tomassini, S.; Turisini, M.; Viticchiè, A.

    2014-12-01

    A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capability in the momentum range from 3 GeV/c to 8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron beam accelerator facility of Jefferson Lab to study the 3D nucleon structure in the yet poorly explored valence region by deep-inelastic scattering, and to perform precision measurements in hadronization and hadron spectroscopy. The adopted solution foresees a novel hybrid optics design based on an aerogel radiator, composite mirrors and densely packed and highly segmented photon detectors. Cherenkov light will either be imaged directly (forward tracks) or after two mirror reflections (large angle tracks). The preliminary results of individual detector component tests and of the prototype performance at test-beams are reported here.

  17. Calibration of the active radiation detector for Spacelab-One

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The flight models of the active radiation detector (ARD) for the ENV-01 environmental monitor were calibrated using gamma radiation. Measured sensitivities of the ion chambers were 6.1 + or - 0.3 micron rad per count for ARD S/N1, and 10.4 + or - 0.5 micron rad per count for ARD S/N2. Both were linear over the measured range 0.10 to 500 m/rad hour. The particle counters (proportional counters) were set to respond to approximately 85% of minimum ionizing particles of unit charge passing through them. These counters were also calibrated in the gamma field.

  18. Performance of the Anti-Coincidence Detector on the GLAST Large Area Telescope

    SciTech Connect

    Thompson, D.J.; Charles, E.; Hartman, R.C.; Moiseev, A.A.; Ormes, J.F.; /NASA, Goddard /Denver U.

    2007-10-22

    The Anti-Coincidence Detector (ACD), the outermost detector layer in the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT), is designed to detect and veto incident cosmic ray charged particles, which outnumber cosmic gamma rays by 3-4 orders of magnitude. The challenge in ACD design is that it must have high (0.9997) detection efficiency for singly-charged relativistic particles, but must also have a low probability for self-veto of high-energy gammas by backsplash radiation from interactions in the LAT calorimeter. Simulations and tests demonstrate that the ACD meets its design requirements. The performance of the ACD has remained stable through stand-alone environmental testing, shipment across the U.S., installation onto the LAT, shipment back across the U.S., LAT environmental testing, and shipment to Arizona. As part of the fully-assembled GLAST observatory, the ACD is being readied for final testing before launch.

  19. Large-area CdTe diode detector for space application

    NASA Astrophysics Data System (ADS)

    Nakazawa, K.; Takahashi, T.; Watanabe, S.; Sato, G.; Kouda, M.; Okada, Y.; Mitani, T.; Kobayashi, Y.; Kuroda, Y.; Onishi, M.; Ohno, R.; Kitajima, H.

    2003-10-01

    The current status of Schottky CdTe diode detectors, especially in view of their space application for hard X-ray and gamma-ray astronomy, are reported. For practical use in space science, a large-area CdTe diode with a size of 21.5×21.5mm2 and a thickness of 0.5mm was developed. A good energy resolution, 2.8keV (FWHM) at -20°C, and high homogeneity to within 0.2% over the detector were achieved for the spectral performance. This device has successfully passed a series of tests required for its use in space, in view of utilizing Japanese M-V rockets. The tests include the mechanical environment test, vacuum test, long run for weeks and proton-beam radiation. Initial results from a 2×2 segmented electrode large-area device with a guard-ring are also presented.

  20. Radial collimator system for reducing background noise during neutron diffraction with area detectors

    NASA Astrophysics Data System (ADS)

    Wright, A. F.; Berneron, M.; Heathman, S. P.

    1981-04-01

    The construction and performance of an area collimator for use with film or multidetectors is described. A cylindrical assembly of high divergence slits, resembling a venetian blind, at a short distance from the sample permits the detector to observe only scattering from the sample or very close to it. Parasitic scattering from cryostats or furnaces enclosing the sample is absorbed by the slits. Homogeneity of transmission is improved by oscillating the collimator.

  1. Application of a CZT detector to in situ environmental radioactivity measurement in the Fukushima area.

    PubMed

    Kowatari, M; Kubota, T; Shibahara, Y; Fujii, T; Fukutani, S; Takamiya, K; Mizuno, S; Yamana, H

    2015-11-01

    Instead of conventional Ge semiconductor detectors and NaI(Tl) scintillation spectrometers, an application of a CdZnTe semiconductor (CZT) whose crystal has the dimension of 1 cm cubic to the in situ environmental radioactivity measurement was attempted in deeply affected areas in Fukushima region. Results of deposition density on soil for (134)Cs/(137)Cs obtained seemed consistent, comparing obtained results with those measured by the Japanese government. PMID:25953790

  2. Investigation of a clinical PET detector module design that employs large-area avalanche photodetectors

    NASA Astrophysics Data System (ADS)

    Peng, Hao; Olcott, Peter D.; Spanoudaki, Virginia; Levin, Craig S.

    2011-06-01

    We investigated the feasibility of designing an Anger-logic PET detector module using large-area high-gain avalanche photodiodes (APDs) for a brain-dedicated PET/MRI system. Using Monte Carlo simulations, we systematically optimized the detector design with regard to the scintillation crystal, optical diffuser, surface treatment, layout of large-area APDs, and signal-to-noise ratio (SNR, defined as the 511 keV photopeak position divided by the standard deviation of noise floor in an energy spectrum) of the APD devices. A detector prototype was built comprising an 8 × 8 array of 2.75 × 3.00 × 20.0 mm3 LYSO (lutetium-yttrium-oxyorthosilicate) crystals and a 22.0 × 24.0 × 9.0 mm3 optical diffuser. From the four designs of the optical diffuser tested, two designs employing a slotted diffuser are able to resolve all 64 crystals within the block with good uniformity and peak-to-valley ratio. Good agreement was found between the simulation and experimental results. For the detector employing a slotted optical diffuser, the energy resolution of the global energy spectrum after normalization is 13.4 ± 0.4%. The energy resolution of individual crystals varies between 11.3 ± 0.3% and 17.3 ± 0.4%. The time resolution varies between 4.85 ± 0.04 (center crystal), 5.17 ± 0.06 (edge crystal), and 5.18 ± 0.07 ns (corner crystal). The generalized framework proposed in this work helps to guide the design of detector modules for selected PET system configurations, including scaling the design down to a preclinical PET system, scaling up to a whole-body clinical scanner, as well as replacing APDs with other novel photodetectors that have higher gain or SNR such as silicon photomultipliers.

  3. Widefield TSCSPC-systems with large-area-detectors: application in simultaneous multi-channel-FLIM

    NASA Astrophysics Data System (ADS)

    Stepanov, Sergei; Bakhlanov, Sergei; Drobchenko, Evgeny; Eckert, Hann-Jörg; Kemnitz, Klaus

    2010-11-01

    Novel proximity-type Time- and Space-Correlated Single Photon Counting (TSCSPC) crossed-delay-line (DL)- and multi-anode (MA)-systems of outstanding performance and homogeneity were developed, using large-area detector heads of 25 and 40 mm diameter. Instrument response functions IRF(space) = (60 +/- 5) μm FWHM and IRF(time) = (28 +/- 3) ps FWHM were achieved over the full 12 cm2 area of the detector. Deadtime at throughput of 105 cps is 10% for "high-resolution" system and 5% in the "video"-system at 106 cps, at slightly reduced time- and space resolution. A fluorescence lifetime of (3.5 +/- 1) ps can be recovered from multi-exponential dynamics of a single living cyanobacterium (Acaryochloris marina). The present large-area detectors are particularly useful in simultaneous multichannel applications, such as 2-colour anisotropy or 4-colour lifetime imaging, utilizing dual- or quad-view image splitters. The long-term stability, low- excitation-intensity (< 100 mW/cm2) widefield systems enable minimal-invasive observation, without significant bleaching or photodynamic reactions, thus allowing long-period observation of up to several hours in living cells.

  4. Active Pixel Sensor Characterization for the STAR Detector

    NASA Astrophysics Data System (ADS)

    King, Jake

    2004-10-01

    The STAR collaboration is studying matter at high temperatures and densities. If a significant improvement to the measurement of particle trajectories can be made, charmed mesons that decay away from the primary collision point could be identified. To achieve this goal, STAR is building a vertex detector consisting of a new technology Â- active pixel sensors. (APS) An APS is an implementation of standard CMOS technology in which each pixel has a photodiode directly above the epitaxial layer. Incident particles produce electron-hole pairs in the epitaxial layer, and these electrons accumulate on the photodiode. Charge from the photodiode is digitized to identify the position of the incident particle. It is important to characterize the signal to noise, readout time, and resolution on several different pixel sizes so that the vertex detector can be optimized for cost and speed. Larger pixels result in a faster data acquisition, while smaller pixels have better resolution. We will present studies of 5, 10, 20 and 30μm square pixel geometries that measure charge distribution and collection. We will also display the results of using a field emission scanning electron microscope with energies from 1 to 30 keV. This tool has the potential to probe regions of the APS integrated circuit and contribute to understanding its properties.

  5. 500 MHz neutron detector

    SciTech Connect

    Yen, Yi-Fen; Bowman, J.D.; Matsuda, Y.

    1993-12-01

    A {sup 10}B-loaded scintillation detector was built for neutron transmission measurements at the Los Alamos Neutron Scattering Center. The efficiency of the detector is nearly 100% for neutron energies from 0 to 1 keV. The neutron moderation time in the scintillator is about 250 ns and is energy independent. The detector and data processing system are designed to handle an instantaneous rate as high as 500 MHz. The active area of the detector is 40 cm in diameter.

  6. New Fast Shower Max Detector Based on MCP as an Active Element

    NASA Astrophysics Data System (ADS)

    Ronzhin, A.; Los, S.; Ramberg, E.; Spiropulu, M.; Apresyan, A.; Xie, S.; Kim, H.; Zatserklyaniy, A.

    2015-02-01

    One possibility to make a fast and radiation resistant shower maximum (SM) detector is to use a secondary emitter as an active element. We present below test beam results, obtained with different types of photo detectors based on micro channel plates (MCP) as secondary emitter. The SM time resolution - we obtained for this new type of detector is at the level of 20-30 ps. We estimate that a significant contribution to the detector response originates from secondary emission of the MCP.

  7. Large area detector based computed tomography system for production nondestructive evaluation.

    SciTech Connect

    Keating, S. C.; Davis, A. A.; Claytor, T. N.

    2001-01-01

    We present a system for industrial x-ray computed tomography that has been optimized for all phases of nondestructive component inspection. Data acquisition is greatly enhanced by the use of high resolution, large area, flat-panel amorphous-silicon detectors. The detectors have proven, over several years, to be a robust alternative to CCD-optics and image intensifier CT systems. In addition to robustness, these detectors provide the advantage of area detection as compared with the single slice geometry of linear array systems. Parallel processing provides significant speed improvements for data reconstruction, and is implemented for parallel-beam, fan-beam and Feldkamp conebeam reconstruction algorithms. By clustering ten or more equal-speed computers, reconstruction times are reduced by an order of magnitude. We have also developed interactive software for visualization and interrogation of the full three-dimensional dataset. Inspection examples presented in this paper include an electro-mechanical device, nonliving biological specimens and a turbo-machinery component. We also present examples of everyday items for the benefit of the layperson.

  8. Large-area, high-speed PIN detectors in GaAs

    NASA Astrophysics Data System (ADS)

    Jackson, D. J.; Persechini, D. L.

    1986-02-01

    Large-area PIN detectors have been manufactured with bandwidths exceeding 8 GHz. The devices were fabricated in concert with design rules for the manufacture of ICs and incorporate an interdigitated format which permits the large detector area with low device capacitance. The PIN detectors were deposited on GaAs substrates. First, an SiO2 layer was deposited, then etched. Next, a 50 nm layer of Zn and then a 50 nm layer of Au were sputter deposited and the interdigitated pattern was defined by photoresist techniques. The electrodes were plated to a 1 micron thickness, the photoresist was removed, and the Zn:Au film was etched away before doping the substrate with Zn and Ge. The device was then sintered at 430 C. A response level of 5 dB/div was obtained over the range 2-8 GHz, with the roll-off point at 8 GHz being 3 dB. The performance levels were achieved without packaging optimization.

  9. Final Scientific/Technical Report Development of Large-Area Photo-Detectors

    SciTech Connect

    Frisch, Henry J.

    2013-07-15

    This proposal requested ADR funds for two years to make measurements and detector proto-types in the context of planning a program in conjunction with Argonne National Laboratory to develop very large-area planar photodetectors. The proposed detectors have integrated transmission-line readout and sampling electronics able to achieve timing and position resolutions in the range of 1-50 psec and 1-10 mm, respectively. The capability for very precise time measurements is inherent in the design, and provides a �third� coordinate, orthogonal to the two in the plane, for the point of origin of photons or charged particles, allowing �tomographic� reconstruction in 3-dimensions inside a volume.

  10. xrayutilities: a versatile tool for reciprocal space conversion of scattering data recorded with linear and area detectors

    PubMed Central

    Kriegner, Dominik; Wintersberger, Eugen; Stangl, Julian

    2013-01-01

    General algorithms to convert scattering data of linear and area detectors recorded in various scattering geometries to reciprocal space coordinates are presented. These algorithms work for any goniometer configuration including popular four-circle, six-circle and kappa goniometers. The use of commonly employed approximations is avoided and therefore the algorithms work also for large detectors at small sample–detector distances. A recipe for determining the necessary detector parameters including mostly ignored misalignments is given. The algorithms are implemented in a freely available open-source package. PMID:24046508

  11. Method of "Active Correlations" for DSSSD detector application

    NASA Astrophysics Data System (ADS)

    Tsyganov, Yu. S.

    2015-01-01

    Real-time PC based algorithm is developed for DSSSD ( Double Side Silicon Strip Detector) detector. Brief description of the detection system is also presented. Complete fusion nuclear reaction nat Yt + 48 Ca → 217 Th is used to test this algorithm at 48Ca beam. Example of successful application of a former algorithm for resistive strip PIPS (resistive strip Passivated Implanted Planar Silicon) detector is presented too.

  12. Demonstration of the First 4H-SiC EUV Detector with Large Detection Area

    NASA Technical Reports Server (NTRS)

    Xin, Xiaobin; Yan, Feng; Koeth, Timothy W.; Hu, Jun; Zhao, Jian H.

    2005-01-01

    Ultraviolet (UV) and Extreme Ultraviolet (EUV) detectors are very attractive in astronomy, photolithography and biochemical applications. For EUV applications, most of the semiconductor detectors based on PN or PIN structures suffer from the very short penetration depth. Most of the carries are absorbed at the surface and recombined there due to the high surface recombination before reach the depletion region, resulting very low quantum efficiency. On the other hand, for Schottky structures, the active region starts from the surface and carriers generated from the surface can be efficiently collected. 4H-Sic has a bandgap of 3.26eV and is immune to visible light background noise. Also, 4H-Sic detectors usually have very good radiation hardness and very low noise, which is very important for space applications where the signal is very weak. The E W photodiodes presented in this paper are based on Schottky structures. Platinum (Pt) and Nickel (Ni) are selected as the Schottky contact metals, which have the highest electron work functions (5.65eV and 5.15eV, respectively) among all the known metals on 4H-Sic.

  13. 10B multi-grid proportional gas counters for large area thermal neutron detectors

    NASA Astrophysics Data System (ADS)

    Andersen, K.; Bigault, T.; Birch, J.; Buffet, J. C.; Correa, J.; Hall-Wilton, R.; Hultman, L.; Höglund, C.; Guérard, B.; Jensen, J.; Khaplanov, A.; Kirstein, O.; Piscitelli, F.; Van Esch, P.; Vettier, C.

    2013-08-01

    3He was a popular material in neutrons detectors until its availability dropped drastically in 2008. The development of techniques based on alternative convertors is now of high priority for neutron research institutes. Thin films of 10B or 10B4C have been used in gas proportional counters to detect neutrons, but until now, only for small or medium sensitive area. We present here the multi-grid design, introduced at the ILL and developed in collaboration with ESS for LAN (large area neutron) detectors. Typically thirty 10B4C films of 1 μm thickness are used to convert neutrons into ionizing particles which are subsequently detected in a proportional gas counter. The principle and the fabrication of the multi-grid are described and some preliminary results obtained with a prototype of 200 cm×8 cm are reported; a detection efficiency of 48% has been measured at 2.5 Å with a monochromatic neutron beam line, showing the good potential of this new technique.

  14. A new acoustic lens material for large area detectors in photoacoustic breast tomography☆

    PubMed Central

    Xia, Wenfeng; Piras, Daniele; van Hespen, Johan C.G.; Steenbergen, Wiendelt; Manohar, Srirang

    2013-01-01

    Objectives We introduce a new acoustic lens material for photoacoustic tomography (PAT) to improve lateral resolution while possessing excellent acoustic acoustic impedance matching with tissue to minimize lens induced image artifacts. Background A large surface area detector due to its high sensitivity is preferable to detect weak signals in photoacoustic mammography. The lateral resolution is then limited by the narrow acceptance angle of such detectors. Acoustic lenses made of acrylic plastic (PMMA) have been used to enlarge the acceptance angle of such detectors and improve lateral resolution. However, such PMMA lenses introduce image artifacts due to internal reflections of ultrasound within the lenses, the result of acoustic impedance mismatch with the coupling medium or tissue. Methods A new lens is proposed based on the 2-component resin Stycast 1090SI. We characterized the acoustic properties of the proposed lens material in comparison with commonly used PMMA, inspecting the speed of sound, acoustic attenuation and density. We fabricated acoustic lenses based on the new material and PMMA, and studied the effect of the acoustic lenses on detector performance comparing finite element (FEM) simulations and measurements of directional sensitivity, pulse-echo response and frequency response. We further investigated the effect of using the acoustic lenses on the image quality of a photoacoustic breast tomography system using k-Wave simulations and experiments. Results Our acoustic characterization shows that Stycast 1090SI has tissue-like acoustic impedance, high speed of sound and low acoustic attenuation. These acoustic properties ensure an excellent acoustic lens material to minimize the acoustic insertion loss. Both acoustic lenses show significant enlargement of detector acceptance angle and lateral resolution improvement from modeling and experiments. However, the image artifacts induced by the presence of an acoustic lens are reduced using the proposed

  15. Large Area Flat Panel Imaging Detectors for Astronomy and Night Time Sensing

    NASA Astrophysics Data System (ADS)

    Siegmund, O.; McPhate, J.; Frisch, H.; Elam, J.; Mane, A.; Wagner, R.; Varner, G.

    2013-09-01

    Sealed tube photo-sensing detectors for optical/IR detection have applications in astronomy, nighttime remote reconnaissance, and airborne/space situational awareness. The potential development of large area photon counting, imaging, timing detectors has significance for these applications and a number of other areas (High energy particle detection (RICH), biological single-molecule fluorescence lifetime imaging microscopy, neutron imaging, time of flight mass spectroscopy, diffraction imaging). We will present details of progress towards the development of a 20 cm sealed tube optical detector with nanoengineered microchannel plates for photon counting, imaging and sub-ns event time stamping. In the operational scheme of the photodetector incoming light passes through an entrance window and interacts with a semitransparent photocathode on the inside of the window. The photoelectrons emitted are accelerated across a proximity gap and are detected by an MCP pair. The pair of novel borosilicate substrate MCPs are functionalized by atomic layer deposition (ALD), and amplify the signal and the resulting electron cloud is detected by a conductive strip line anode for determination of the event positions and the time of arrival. The physical package is ~ 25 x 25 cm but only 1.5 cm thick. Development of such a device in a square 20 cm format presents challenges: hermetic sealing to a large entrance window, a 20 cm semitransparent photocathode with good efficiency and uniformity, 20 cm MCPs with reasonable cost and performance, robust construction to preserve high vacuum and withstand an atmosphere pressure differential. We will discuss the schemes developed to address these issues and present the results for the first test devices. The novel microchannel plates employing borosilicate micro-capillary arrays provide many performance characteristics typical of conventional MCPs, but have been made in sizes up to 20 cm, have low intrinsic background (0.08 events cm2 s-1) and

  16. High resolution micro-CT of low attenuating organic materials using large area photon-counting detector

    NASA Astrophysics Data System (ADS)

    Kumpová, I.; Vavřík, D.; Fíla, T.; Koudelka, P.; Jandejsek, I.; Jakůbek, J.; Kytýř, D.; Zlámal, P.; Vopálenský, M.; Gantar, A.

    2016-02-01

    To overcome certain limitations of contemporary materials used for bone tissue engineering, such as inflammatory response after implantation, a whole new class of materials based on polysaccharide compounds is being developed. Here, nanoparticulate bioactive glass reinforced gelan-gum (GG-BAG) has recently been proposed for the production of bone scaffolds. This material offers promising biocompatibility properties, including bioactivity and biodegradability, with the possibility of producing scaffolds with directly controlled microgeometry. However, to utilize such a scaffold with application-optimized properties, large sets of complex numerical simulations using the real microgeometry of the material have to be carried out during the development process. Because the GG-BAG is a material with intrinsically very low attenuation to X-rays, its radiographical imaging, including tomographical scanning and reconstructions, with resolution required by numerical simulations might be a very challenging task. In this paper, we present a study on X-ray imaging of GG-BAG samples. High-resolution volumetric images of investigated specimens were generated on the basis of micro-CT measurements using a large area flat-panel detector and a large area photon-counting detector. The photon-counting detector was composed of a 010× 1 matrix of Timepix edgeless silicon pixelated detectors with tiling based on overlaying rows (i.e. assembled so that no gap is present between individual rows of detectors). We compare the results from both detectors with the scanning electron microscopy on selected slices in transversal plane. It has been shown that the photon counting detector can provide approx. 3× better resolution of the details in low-attenuating materials than the integrating flat panel detectors. We demonstrate that employment of a large area photon counting detector is a good choice for imaging of low attenuating materials with the resolution sufficient for numerical simulations.

  17. Development of large area, pico-second resolution photo-detectors and associated readout electronics

    SciTech Connect

    Grabas, H.; Oberla, E.; Attenkoffer, K.; Bogdan, M.; Frisch, H. J.; Genat, J. F.; May, E. N.; Varner, G. S.; Wetstein, M.

    2011-07-01

    The Large Area Pico-second Photo-detectors described in this contribution incorporate a photo-cathode and a borosilicate glass capillary Micro-Channel Plate (MCP) pair functionalized by atomic layer deposition (ALD) of separate resistive and electron secondary emitters materials. They may be used for biomedical imaging purposes, a remarkable opportunity to apply technologies developed in HEP having the potential to make major advances in the medical world, in particular for Positron Emission Tomography (PET). If daisy-chained and coupled to fast transmission lines read at both ends, they could be implemented in very large dimensions. Initial testing with matched pairs of small glass capillary test has demonstrated gains of the order of 105 to 106. Compared to other fast imaging devices, these photo-detectors are expected to provide timing resolutions in the 10-100 ps range, and two-dimension position in the sub-millimeter range. A 6-channel readout ASIC has been designed in 130 nm CMOS technology and tested. As a result, fast analog sampling up to 17 GS/s has been obtained, the intrinsic analog bandwidth being presently under evaluation. The digitization in parallel of several cells in two microseconds allows getting off-chip digital data read at a maximum rate of 40 MHz. Digital Signal Processing of the sampled waveforms is expected achieving the timing and space resolutions obtained with digital oscilloscopes. (authors)

  18. A large area cosmic muon detector located at Ohya stone mine

    NASA Technical Reports Server (NTRS)

    Nii, N.; Mizutani, K.; Aoki, T.; Kitamura, T.; Mitsui, K.; Matsuno, S.; Muraki, Y.; Ohashi, Y.; Okada, A.; Kamiya, Y.

    1985-01-01

    The chemical composition of the primary cosmic rays between 10 to the 15th power eV and 10 to the 18th power eV were determined by a Large Area Cosmic Muon Detector located at Ohya stone mine. The experimental aims of Ohya project are; (1) search for the ultra high-energy gamma-rays; (2) search for the GUT monopole created by Big Bang; and (3) search for the muon bundle. A large number of muon chambers were installed at the shallow underground near Nikko (approx. 100 Km north of Tokyo, situated at Ohya-town, Utsunomiya-city). At the surface of the mine, very fast 100 channel scintillation counters were equipped in order to measure the direction of air showers. These air shower arrays were operated at the same time, together with the underground muon chamber.

  19. Portable digital electronic radiography system with a solid-state area-imaging detector

    NASA Astrophysics Data System (ADS)

    Sawicka, Barbara D.; Reynolds, Paul; Sonnenburg, Ken

    1999-06-01

    A digital system for radiographic inspection was constructed in a portable version suitable for field use. The system uses typical film radiography sources, including 60Co, 192Ir and X-ray generators. Radiographic images are formed using an area-imaging scintillating detector coupled to a charge-coupled device camera and a portable industrial computer. Compared to film radiography, this technology offers imaging without wet-film processing, shorter exposure times, larger dynamic range, and digital imaging that permits compact archiving, easy data access and mathematical image processing to improve sensitivity. System performance is illustrated for typical applications, i.e., for radiographing valves and pipes. Using 192Ir, the system works well on smaller water-filled valves and pipes; larger valves have to be drained. Work is under way to address this problem.

  20. Considerations about Large Area___Low Cost Fast Imaging Photo-detectors

    SciTech Connect

    Anderson, John; Attenkofer, Klaus; Delagnes, Eric; Frisch, Henry; Genat, Jean-Francois; Grabas, Herve; Heintz, Mary K.; May, Edward; Meehan, Samuel; Oberla, Eric; Ruckman, Larry L.; Tang, Fukun; Varner, Gary; Vavra, Jaroslav; Wetstein, Matthew; /Argonne

    2012-05-07

    The Large Area Picosecond Photodetectors described in this contribution incorporate a photocathode and a borosilicate glass capillary Micro-Channel Plate (MCP) pair functionalised by atomic layer deposition (ALD) of separate resistive and secondary emission materials. Initial testing with matched pairs of small glass capillary test disks has demonstrated gains of the order of 10{sup 5}-10{sup 6}. Compared to other fast imaging devices, these photodetectors are expected to provide timing resolutions in the 10-100 ps range, and two-dimension position in the sub-millimeter range. If daisy chained, large detectors read at both ends with fast digitising integrated electronics providing zero-suppressed calibrated data should be produced at relatively low cost in large quantities.

  1. Quantification of thin film crystallographic orientation using X-ray diffraction with an area detector

    SciTech Connect

    Baker, Jessica L; Jimison, Leslie H; Mannsfeld, Stefan; Volkman, Steven; Yin, Shong; Subramanian, Vivek; Salleo, Alberto; Alivisatos, A Paul; Toney, Michael F

    2010-02-19

    As thin films become increasingly popular (for solar cells, LEDs, microelectronics, batteries), quantitative morphological information is needed to predict and optimize the film's electronic, optical and mechanical properties. This quantification can be obtained quickly and easily with X-ray diffraction using an area detector and synchrotron radiation in two simple geometries. In this paper, we describe a methodology for constructing complete pole figures for thin films with fiber texture (isotropic in-plane orientation). We demonstrate this technique on semicrystalline polymer films, self-assembled nanoparticle semiconductor films, and randomly-packed metallic nanoparticle films. This method can be immediately implemented to help understand the relationship between film processing and microstructure, enabling the development of better and less expensive electronic and optoelectronic devices.

  2. DEPFET Active Pixel Detectors for a Future Linear e(+}e({-)) Collider

    NASA Astrophysics Data System (ADS)

    Alonso, O.; Casanova, R.; Dieguez, A.; Dingfelder, J.; Hemperek, T.; Kishishita, T.; Kleinohl, T.; Koch, M.; Kruger, H.; Lemarenko, M.; Lutticke, F.; Marinas, C.; Schnell, M.; Wermes, N.; Campbell, A.; Ferber, T.; Kleinwort, C.; Niebuhr, C.; Soloviev, Y.; Steder, M.; Volkenborn, R.; Yaschenko, S.; Fischer, P.; Kreidl, C.; Peric, I.; Knopf, J.; Ritzert, M.; Curras, E.; Lopez-Virto, A.; Moya, D.; Vila, I.; Boronat, M.; Esperante, D.; Fuster, J.; Garcia, I. Garcia; Lacasta, C.; Oyanguren, A.; Ruiz, P.; Timon, G.; Vos, M.; Gessler, T.; Kuhn, W.; Lange, S.; Munchow, D.; Spruck, B.; Frey, A.; Geisler, C.; Schwenker, B.; Wilk, F.; Barvich, T.; Heck, M.; Heindl, S.; Lutz, O.; Muller, Th.; Pulvermacher, C.; Simonis, H. J.; Weiler, T.; Krausser, T.; Lipsky, O.; Rummel, S.; Schieck, J.; Schluter, T.; Ackermann, K.; Andricek, L.; Chekelian, V.; Chobanova, V.; Dalseno, J.; Kiesling, C.; Koffmane, C.; Gioi, L. Li; Moll, A.; Moser, H. G.; Muller, F.; Nedelkovska, E.; Ninkovic, J.; Petrovics, S.; Prothmann, K.; Richter, R.; Ritter, A.; Ritter, M.; Simon, F.; Vanhoefer, P.; Wassatsch, A.; Dolezal, Z.; Drasal, Z.; Kodys, P.; Kvasnicka, P.; Scheirich, J.

    2013-04-01

    The DEPFET collaboration develops highly granular, ultra-transparent active pixel detectors for high-performance vertex reconstruction at future collider experiments. The characterization of detector prototypes has proven that the key principle, the integration of a first amplification stage in a detector-grade sensor material, can provide a comfortable signal to noise ratio of over 40 for a sensor thickness of 50-75 $\\mathrm{\\mathbf{\\mu m}}$. ASICs have been designed and produced to operate a DEPFET pixel detector with the required read-out speed. A complete detector concept is being developed, including solutions for mechanical support, cooling and services. In this paper the status of DEPFET R & D project is reviewed in the light of the requirements of the vertex detector at a future linear $\\mathbf{e^+ e^-}$ collider.

  3. Spectral measurements of neutrons produced by 52 MeV protons with activation detectors

    NASA Astrophysics Data System (ADS)

    Shin, Kazuo; Saito, Takatsugu; Fujii, Masahiko; Nakamura, Takashi

    The accuracy of the neutron spectral measurement of energy up to ˜40 MeV with activation detectors was examined using high energy neutrons from thick targets bombarded by 52 MeV protons. The measured activation rates were unfolded with the modified SAND-II code and compared with the neutron spectra measured by the NE-213 scintillator. Quite good agreement in absolute values was obtained between the spectra recorded by these two different detectors. The activation detector was shown to be useful for neutron spectroscopy at energies higher than ˜ 10 MeV.

  4. Development and evaluation of a digital radiography system using a large-area flat-panel detector

    NASA Astrophysics Data System (ADS)

    Suzuki, Katsumi; Ikeda, Shigeyuki; Ishikawa, Ken; Iinuma, Gen; Ogasawara, Satoshi; Moriyama, Noriyuki; Konno, Yasutaka

    2002-05-01

    A new DR system using a large-area flat panel detector (FPD) with a 40 by 30 cm active area and a 194 micrometers pixel pitch, has been developed to compare with a conventional image intensifier and charge-coupled device camera type DR system. After measuring basic characteristics of the new DR system such as signal-to-noise ratio, modulation transfer function, and detective quantum efficiency, we applied the FPD to a Gastro-Intestinal study with contrast media, and discussed its potential for clinical use with a medical doctor. In radiography mode, the new DR system with a large-are FPD has superior image quality compared with the conventional I.I.- CCD camera type DR system because of high SNR and DQE. In fluoroscopy mode, the SNR of the new DR system at the exposure range of over 2(mu) R/frame is similar with the conventional I.I.-CCD camera type DR system. As a result, we considered that new DR system with a large-area FPD could be applied to a clinical study replacing an I.I.-CCD camera type. In the evaluation using various clinical images taken with the new DR system by a medical doctor, the new DR system with a large-are FPD performed sufficiently for a GI study.

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

    SciTech Connect

    Nelson, Karl Einar; Burks, Morgan T

    2014-04-22

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

  6. LAMBDA: Large Area Modular BaF2 Detector Array for the measurement of high energy γ rays

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, S.; Bhattacharya, Srijit; Pandit, Deepak; Ray, A.; Pal, Surajit; Banerjee, K.; Kundu, S.; Rana, T. K.; Bhattacharya, S.; Bhattacharya, C.; De, A.; Banerjee, S. R.

    2007-11-01

    A large BaF 2 detector array along with its dedicated CAMAC electronics and VME based data acquisition system has been designed, constructed and installed successfully at VECC, Kolkata for studying high energy γ rays ( >8 MeV). The array consists of 162 detector elements. The detectors were fabricated from bare barium fluoride crystals (each measuring 35 cm in length and having cross-sectional area of 3.5×3.5 cm2). The basic properties of the detectors (energy resolution, time resolution, efficiency, uniformity, fast to slow ratio, etc.) were studied exhaustively. Complete GEANT3 Monte Carlo simulations were performed to optimize the detector design and also to generate the response function. The detector system has been used successfully to measure high energy photons from 113Sb, formed by bombarding 145 and 160 MeV 20Ne beams on a 93Nb target. The measured experimental spectra are in good agreement with those from a modified version of the statistical model code CASCADE. In this paper, we present the complete description of this detector array along with its in-beam performance.

  7. Large-sensitive-area superconducting nanowire single-photon detector at 850 nm with high detection efficiency.

    PubMed

    Li, Hao; Zhang, Lu; You, Lixing; Yang, Xiaoyan; Zhang, Weijun; Liu, Xiaoyu; Chen, Sijing; Wang, Zhen; Xie, Xiaoming

    2015-06-29

    Satellite-ground quantum communication requires single-photon detectors of 850-nm wavelength with both high detection efficiency and large sensitive area. We developed superconducting nanowire single-photon detectors (SNSPDs) on one-dimensional photonic crystals, which acted as optical cavities to enhance the optical absorption, with a sensitive-area diameter of 50 μm. The fabricated multimode fiber coupled NbN SNSPDs exhibited a maximum system detection efficiency (DE) of up to 82% and a DE of 78% at a dark count rate of 100 Hz at 850-nm wavelength as well as a system jitter of 105 ps. PMID:26191739

  8. Early operating experience with large-area germanium detectors for detecting low-energy photons

    SciTech Connect

    Rieksts, G.A.; Lynch, T.P.; Olsen, P.C.

    1994-11-01

    Intrinsic germanium (Ge) planar detector arrays have been used at Hanford for lung counting since 1983. This paper describes a counting system using an array of only four detectors, larger than those used in the past, using larger dewars and a simplified detector-positioning system. Typical detector elements have been 51 mm in diameter and 20 mm thick, with a beryllium window thickness of 0.51 mm. The resolution of the detectors has been about 560 eV for 6.4-keV x-rays and 700 eV for 122-keV gamma rays. In the past, arrays of three, four, five, and six detectors have been employed. Six detectors have been the preferred configuration for lung counting. Up to 3,000 counts annually have been performed with these systems. When detectors fail and spares are not available, calibrations and calculational algorithms are maintained for four-detector configurations. For several years, both ``bucket`` and ``stovepipe`` designs have been used for the Dewars with the 15-liter dewars proving to be much more reliable than the ``stovepipe`` designs.

  9. A large area plastic scintillation detector with 4-corner-readout

    NASA Astrophysics Data System (ADS)

    Tang, Shu-Wen; Yu, Yu-Hong; Zhou, Yong; Sun, Zhi-Yu; Zhang, Xue-Heng; Wang, Shi-Tao; Yue, Ke; Liu, Long-Xiang; Fang, Fang; Yan, Duo; Sun, Yu; Wang, Zhao-Min

    2016-05-01

    A 760 mm × 760 mm × 30 mm plastic scintillation detector viewed by photomultiplier tubes (PMTs) from four corners has been developed, and the detector has been tested with cosmic rays and γ rays. A position-independent effective time T eff has been found, indicating this detector can be used as a TOF detector. The hit position can also be reconstructed by the time from the four corners. A TOF resolution of 236 ps and a position resolution of 48 mm have been achieved, and the detection efficiency has also been investigated. Supported by National Natural Science Foundation of China (U1332207, 11405242)

  10. Development of Large Area Gas Electron Multiplier Detector and Its Application to a Digital Hadron Calorimeter for Future Collider Experiments

    SciTech Connect

    Yu, Jaehoon; White, Andrew

    2014-09-25

    The UTA High Energy Physics Group conducted generic detector development based on large area, very thin and high sensitivity gas detector using gas electron multiplier (GEM) technology. This is in preparation for a use as a sensitive medium for sampling calorimeters in future collider experiments at the Energy Frontier as well as part of the tracking detector in Intensity Frontier experiments. We also have been monitoring the long term behavior of one of the prototype detectors (30cmx30cm) read out by the SLAC-developed 13-bit KPiX analog chip over three years and have made presentations of results at various APS meetings. While the important next step was the development of large area (1m x 1m) GEM planes, we also have looked into opportunities of applying this technology to precision tracking detectors to significantly improve the performance of the Range Stack detector for CP violation experiments and to provide an amplification layer for the liquid Argon Time Projection Chamber in the LBNE experiment. We have jointly developed 33cmx100cm large GEM foils with the CERN gas detector development group to construct 33cm x100cm unit chambers. Three of these unit chambers will be put together to form a 1m x 1m detector plane. Following characterization of one 33cmx100cm unit chamber prototype, a total of five 1m x 1m planes will be constructed and inserted into an existing 1m3 RPC DHCAL stack to test the performance of the new GEM DHCAL in particle beams. The large area GEM detector we planned to develop in this proposal not only gives an important option to DHCAL for future collider experiments but also the potential to expand its use to Intensity Frontier and Cosmic Frontier experiments as high efficiency, high amplification anode planes for liquid Argon time projection chambers. Finally, thanks to its sensitivity to X-rays and other neutral radiations and its light-weight characteristics, the large area GEM has a great potential for the use in medical imaging and

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  12. Fast and precise large area metrology of micropattern detectors using laser distance sensors

    NASA Astrophysics Data System (ADS)

    Müller, R.; Biebel, O.; Hertenberger, R.; Lösel, P.; Schaile, O.

    2016-07-01

    Novel developments in micropattern detector technology require fast and precise methods to measure large area topologies in the order of a few square meters. Standard tactile coordinate measurement systems have resolutions better 10 μm, but suffer from relatively long measuring time of several hours for one cycle. Sensitive structures may be damaged when touched by the tactile sensor. We present a method using laser distance sensors. Such a device is able to scan surfaces fast without touching them. The presented device has the capability to measure semitransparent surfaces. The vertical translator to mount the sensor is able to move in sub-mm steps. Using this we are able to measure the position and height of copper on FR4 with an accuracy better than 10 μm. We report on the performance of the sensor scanning non-transparent as well as semi-transparent surfaces. This includes studies to minimize the measurement time without a loss in resolution. Our method to calibrate the measurement system will also be shown. This calibration is needed to reach a resolution better than 10 μm.

  13. Development of a large-area CMOS-based detector for real-time x-ray imaging

    NASA Astrophysics Data System (ADS)

    Heo, Sung Kyn; Park, Sung Kyu; Hwang, Sung Ha; Im, Dong Ak; Kosonen, Jari; Kim, Tae Woo; Yun, Seungman; Kim, Ho Kyung

    2010-04-01

    Complementary metal-oxide-semiconductor (CMOS) active pixel sensors (APSs) with high electrical and optical performances are now being attractive for digital radiography (DR) and dental cone-beam computed tomography (CBCT). In this study, we report our prototype CMOS-based detectors capable of real-time imaging. The field-of-view of the detector is 12 × 14.4 cm. The detector employs a CsI:Tl scintillator as an x-ray-to-light converter. The electrical performance of the CMOS APS, such as readout noise and full-well capacity, was evaluated. The x-ray imaging characteristics of the detector were evaluated in terms of characteristic curve, pre-sampling modulation transfer function, noise power spectrum, detective quantum efficiency, and image lag. The overall performance of the detector is demonstrated with phantom images obtained for DR and CBCT applications. The detailed development description and measurement results are addressed. With the results, we suggest that the prototype CMOS-based detector has the potential for CBCT and real-time x-ray imaging applications.

  14. High Performance Measurement System of Large Area Solid-State Track Detector Array for Ultra Heavy Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Kodaira, S.; Doke, T.; Hareyama, M.; Hasebe, N.; Sakurai, K.; Ota, S.; Sato, M.; Yasuda, N.; Nakamura, S.; Kamei, T.; Tawara, H.; Ogura, K.

    The handling of solid-state track detector (SSTD) has been historically required for a long period and many human powers to scan and analyze etch-pits produced on the detector. Because a large area greater than a few m2 detector is required to observe ultraheavy nuclei in galactic cosmic rays, a high speed scanning system is practically important to realize our observation. We have developed the fast automated digital imaging optical microscope (HSP-1000) to scan and analyze the etch-pit produced on the detector, whose image acquisition speed is 50-100 times faster than conventional microscope system. Furthermore, analyzing massive cosmic ray track data produced in extremely large exposed area requires a completely automated multi-sample scanning system. The developed automated system consists of a modified HSP-1000 microscope for image acquisition, a robot arm to replace the sample trays, a magazine station for storing sample trays, and a scanning and analyzing computer to control the whole system. Moreover, since the improvement of thickness measurement accuracy in local area of SSTD will allow us to achieve higher charge and mass resolutions, the new system to measure the SSTD thickness located adjacent to etch-pit in SSTD with an excellent resolution of +/- 0.2 um has been developed.

  15. Direct tests of micro channel plates as the active element of a new shower maximum detector

    SciTech Connect

    Ronzhin, A.; Los, S.; Ramberg, E.; Apresyan, A.; Xie, S.; Spiropulu, M.; Kim, H.

    2015-05-22

    We continue the study of micro channel plates (MCP) as the active element of a shower maximum (SM) detector. We present below test beam results obtained with MCPs detecting directly secondary particles of an electromagnetic shower. The MCP efficiency to shower particles is close to 100%. Furthermore, the time resolution obtained for this new type of the SM detector is at the level of 40 ps.

  16. Direct tests of micro channel plates as the active element of a new shower maximum detector

    NASA Astrophysics Data System (ADS)

    Ronzhin, A.; Los, S.; Ramberg, E.; Apresyan, A.; Xie, S.; Spiropulu, M.; Kim, H.

    2015-09-01

    We continue the study of micro channel plates (MCP) as the active element of a shower maximum (SM) detector. We present below test beam results obtained with MCPs detecting directly secondary particles of an electromagnetic shower. The MCP efficiency to shower particles is close to 100%. The time resolution obtained for this new type of the SM detector is at the level of 40 ps.

  17. The Muon Portal Project: A large-area tracking detector for muon tomography

    NASA Astrophysics Data System (ADS)

    Riggi, F.

    2016-05-01

    The Muon Portal Project [1] is a joint initiative between research and industrial partners, aimed at the construction of a real size detector protoype to search for hidden high-Z fissile materials inside containers by the muon scattering technique. The detector is based on a set of 48 detection modules (1 m × 3 m), so as to provide four X-Y detection planes, two placed above and two below the container to be inspected. After a research and development phase, which led to the choice and test of the individual components, the construction of the full size detector has already started and will be completed in a few months.

  18. Large area Si low-temperature light detectors with Neganov-Luke effect

    NASA Astrophysics Data System (ADS)

    Biassoni, M.; Brofferio, C.; Capelli, S.; Cassina, L.; Clemenza, M.; Cremonesi, O.; Faverzani, M.; Ferri, E.; Giachero, A.; Gironi, L.; Giordano, C.; Gotti, C.; Maino, M.; Margesin, B.; Nucciotti, A.; Pavan, M.; Pessina, G.; Previtali, E.; Puiu, A.; Sisti, M.; Terranova, F.

    2015-10-01

    Next generation calorimetric experiments for the search of rare events rely on the detection of tiny amounts of light (of the order of 20 optical photons) to discriminate and reduce background sources and improve sensitivity. Calorimetric detectors are the simplest solution for photon detection at cryogenic (mK) temperatures. The development of silicon based light detectors with enhanced performance thanks to the use of the Neganov-Luke effect is described. The aim of this research line is the production of high performance detectors with industrial-grade reproducibility and reliability.

  19. Neutron Damage in Mechanically-Cooled High-Purity Germanium Detectors for Field-Portable Prompt Gamma Neutron Activation Analysis (PGNAA) Systems

    SciTech Connect

    E.H. Seabury; C.J. Wharton; A.J. Caffrey; J.B. McCabe; C. DeW. Van Siclen

    2013-10-01

    Prompt Gamma Neutron Activation (PGNAA) systems require the use of a gamma-ray spectrometer to record the gamma-ray spectrum of an object under test and allow the determination of the object’s composition. Field-portable systems, such as Idaho National Laboratory’s PINS system, have used standard liquid-nitrogen-cooled high-purity germanium (HPGe) detectors to perform this function. These detectors have performed very well in the past, but the requirement of liquid-nitrogen cooling limits their use to areas where liquid nitrogen is readily available or produced on-site. Also, having a relatively large volume of liquid nitrogen close to the detector can impact some assessments, possibly leading to a false detection of explosives or other nitrogen-containing chemical. Use of a mechanically-cooled HPGe detector is therefore very attractive for PGNAA applications where nitrogen detection is critical or where liquid-nitrogen logistics are problematic. Mechanically-cooled HPGe detectors constructed from p-type germanium, such as Ortec’s trans-SPEC, have been commercially available for several years. In order to assess whether these detectors would be suitable for use in a fielded PGNAA system, Idaho National Laboratory (INL) has been performing a number of tests of the resistance of mechanically-cooled HPGe detectors to neutron damage. These detectors have been standard commercially-available p-type HPGe detectors as well as prototype n-type HPGe detectors. These tests compare the performance of these different detector types as a function of crystal temperature and incident neutron fluence on the crystal.

  20. Development of large area polycrystalline diamond detectors for fast timing application of high-energy heavy-ion beams

    NASA Astrophysics Data System (ADS)

    Schirru, F.; Nara Singh, B. S.; Scruton, L.; Bentley, M. A.; Fox, S. P.; Lohstroh, A.; Sellin, P. J.; Banu, A.; McCleskey, M.; Roeder, B. T.; Simmons, E.; Alharbi, A. A.; Trache, L.; Freer, M.; Parker, D.

    2012-05-01

    We have studied the effects of electrode fabrication and detector capacitance on the time resolution of large area electronic grade polycrystalline chemical vapour deposited diamond sensors that are suitable for time of flight measurements of heavy ions at relativistic velocities. Sensors were prepared both in house, with Al or Au metal contacts, and commercially fabricated with Au/diamond-like carbon contacts. 3He, 40Ar and a mixture of 20Ne and 16O beams at 16.3, 33.5 and 21-23 MeV/u, respectively were used on these devices whilst arranged in transmission geometry. Signal processing only began over one meter away from the sensors. The present approach, where we have large-area/large capacitance multi-strip detectors with processing electronics at some distance from the target, is compatible with anticipated space limitations in particle-identification and tracking setups at existing and planned nuclear fragmentation facilities. In a systematic study under these conditions, we demonstrate that the time resolution is limited by detector capacitance and energy deposition in the sensors. An intrinsic time resolution σt = (44±5) ps was achieved for a diamond detector of ~ 14 pF capacitance. We conclude that, once further refinements are made, a large area time of flight detection system using polycrystalline diamond detectors would be able to provide time resolutions better than 40 ps, approaching the requirement for particle-identification in relativistic fragmentation experiments, such as those at the facility for antiproton and ion research, FAIR.

  1. The new large-area wide-angle ground-based cosmic-ray and gamma-ray detector SCORE

    NASA Astrophysics Data System (ADS)

    Tluczykont, Martin; Hampf, Daniel; Horns, Dieter; Kneiske, Tanja; Rowell, Gavin

    We propose to explore the so-far poorly measured cosmic-ray and gamma-ray sky (accelerator sky) in the energy range from 10 TeV to 1 EeV with the new large-area (10 square-km) wide-angle (1 sr) air Cherenkov detector SCORE (Study for a Cosmic ORigin Explorer). The SCORE detector concept is based on non-imaging Cherenkov light-front sampling with sensitive large-area (order of square-m) detector modules, distributed over an array covering a total area of at least 10 square-kilometers. The lateral intensity and arrival-time distribu-tions will be sampled with high sensitivity up to large distances from the shower core. An extension of the SCORE detector to HiSCORE (Hundred Square-km Cosmic ORigin Explorer) is planned. With SCORE (and HiSCORE) fundamental physics questions can be addressed, including the origin of charged Galactic cosmic rays, diffuse gamma-ray emission from the Galactic plane and the local super-cluster, attenuation by Galactic interstellar radiaton fields and the cosmic microwave background and studies of possible effects on this attenuation by photon/axion conversion, hidden-sector photon oscillations or violation of Lorentz invariance. Further motivations are spectral and chemical composition measurements of charged cosmic rays from 100 TeV to 1 EeV and independent measurements of the proton-proton inelastic cross-section overlapping with and exceeding LHC energies. First simulations show that already SCORE has the potential to be competitive with existing and planned experiments above 10 TeV and outperforming above 100 TeV. The physics moti-vations, the detector concept / performance expectations and the status of our project will be presented.

  2. Design and Test of an Event Detector and Locator for the ReflectoActive Seals System

    SciTech Connect

    Stinson, Brad J

    2006-06-01

    The purpose of this work was to research, design, develop and test a novel instrument for detecting fiber optic loop continuity and spatially locating fiber optic breaches. The work is for an active seal system called ReflectoActive{trademark} Seals whose purpose is to provide real time container tamper indication. A Field Programmable Gate Array was used to implement a loop continuity detector and a spatial breach locator based on a high acquisition speed single photon counting optical time domain reflectometer. Communication and other control features were added in order to create a usable instrument that met defined requirements. A host graphical user interface was developed to illustrate system use and performance. The resulting device meets performance specifications by exhibiting a dynamic range of 27dB and a spatial resolution of 1.5 ft. The communication scheme used expands installation options and allows the device to communicate to a central host via existing Local Area Networks and/or the Internet.

  3. Design and Test of an Event Detector for the ReflectoActive Seals System

    SciTech Connect

    Stinson, Brad J

    2006-05-01

    The purpose of this thesis was to research, design, develop and test a novel instrument for detecting fiber optic loop continuity and spatially locating fiber optic breaches. The work is for an active seal system called ReflectoActive Seals whose purpose is to provide real time container tamper indication. A Field Programmable Gate Array was used to implement a loop continuity detector and a spatial breach locator based on a high acquisition speed single photon counting optical time domain reflectometer. Communication and other control features were added in order to create a usable instrument that met defined requirements. A host graphical user interface was developed to illustrate system use and performance. The resulting device meets performance specifications by exhibiting a dynamic range of 27dB and a spatial resolution of 1.5 ft. The communication scheme used expands installation options and allows the device to communicate to a central host via existing Local Area Networks and/or the Internet.

  4. Large-area NbN superconducting nanowire avalanche photon detectors with saturated detection efficiency

    NASA Astrophysics Data System (ADS)

    Murphy, Ryan P.; Grein, Matthew E.; Gudmundsen, Theodore J.; McCaughan, Adam; Najafi, Faraz; Berggren, Karl K.; Marsili, Francesco; Dauler, Eric A.

    2015-05-01

    Superconducting circuits comprising SNSPDs placed in parallel—superconducting nanowire avalanche photodetectors, or SNAPs—have previously been demonstrated to improve the output signal-to-noise ratio (SNR) by increasing the critical current. In this work, we employ a 2-SNAP superconducting circuit with narrow (40 nm) niobium nitride (NbN) nanowires to improve the system detection efficiency to near-IR photons while maintaining high SNR. Additionally, while previous 2-SNAP demonstrations have added external choke inductance to stabilize the avalanching photocurrent, we show that the external inductance can be entirely folded into the active area by cascading 2-SNAP devices in series to produce a greatly increased active area. We fabricated series-2-SNAP (s2-SNAP) circuits with a nanowire length of 20 μm with cascades of 2-SNAPs providing the choke inductance necessary for SNAP operation. We observed that (1) the detection efficiency saturated at high bias currents, and (2) the 40 nm 2-SNAP circuit critical current was approximately twice that for a 40 nm non-SNAP configuration.

  5. NASA's Spaceliner 100 Investment Area Technology Activities

    NASA Technical Reports Server (NTRS)

    Hueter, Uwe; Lyles, Garry M. (Technical Monitor)

    2001-01-01

    NASA's has established long term goals for access-to-space. The third generation launch systems are to be fully reusable and operational around 2025. The goals for the third generation launch system are to reduce cost by a factor of 100 and improve safety by a factor of 10,000 over current conditions. The Advanced Space Transportation Program Office (ASTP) at the NASA's Marshall Space Flight Center in Huntsville, AL has the agency lead to develop space transportation technologies. Within ASTP, under the Spaceliner100 Investment Area, third generation technologies are being pursued in the areas of propulsion, airframes, integrated vehicle health management (IVHM), launch systems, and operations and range. The ASTP program will mature these technologies through ground system testing. Flight testing where required, will be advocated on a case by case basis.

  6. NASA's Spaceliner Investment Area Technology Activities

    NASA Technical Reports Server (NTRS)

    Hueter, Uwe; Lyles, Garry M. (Technical Monitor)

    2001-01-01

    NASA's has established long term goals for access-to-space. The third generation launch systems are to be fully reusable and operational around 2025. The goals for the third generation launch system are to significantly reduce cost and improve safety over current conditions. The Advanced Space Transportation Program Office (ASTP) at the NASA's Marshall Space Flight Center in Huntsville, AL has the agency lead to develop space transportation technologies. Within ASTP, under the Spaceliner Investment Area, third generation technologies are being pursued in the areas of propulsion, airframes, integrated vehicle health management (IVHM), avionics, power, operations, and range. The ASTP program will mature these technologies through both ground and flight system testing. The Spaceliner Investment Area plans to mature vehicle technologies to reduce the implementation risks for future commercially developed reusable launch vehicles (RLV). The plan is to substantially increase the design and operating margins of the third generation RLV (the Space Shuttle is the first generation) by incorporating advanced technologies in propulsion, materials, structures, thermal protection systems, avionics, and power. Advancements in design tools and better characterization of the operational environment will allow improvements in design margins. Improvements in operational efficiencies will be provided through use of advanced integrated health management, operations, and range technologies. The increase in margins will allow components to operate well below their design points resulting in improved component operating life, reliability, and safety which in turn reduces both maintenance and refurbishment costs. These technologies have the potential of enabling horizontal takeoff by reducing the takeoff weight and achieving the goal of airline-like operation. These factors in conjunction with increased flight rates from an expanding market will result in significant improvements in safety

  7. Active Inspection of Nuclear Materials Using {sup 4}He Scintillation Detectors

    SciTech Connect

    Davatz, G.; Howard, A.; Chandra, R.; Gendotti, U.

    2011-12-13

    The detection of fissionable materials by neutron and high-energy photon active interrogation methods is explored using {sup 4}He scintillation detectors to search for prompt and delayed neutron signature. The low electron density of {sup 4}He in addition to its pulse shape discrimination capability allows strong rejection of gamma radiation. For the detection of the prompt neutron signatures, this capability is important as the signal produced by induced fission is accompanied by intense gamma radiation. The nanosecond time resolution of {sup 4}He scintillation detectors can be used for time-of-flight measurements aimed at determining the energy of the emitted neutrons. For delayed neutron detection, the insensitivity to the low energy neutrons present from non-signal reactions is inherent. Unlike detectors requiring a moderator, this technology can easily be collimated to reduce sensitivity to neutrons from outside the field of interest. The performance of the detectors for these applications is studied using GEANT4 computer modeling, based on measured detector parameters. A comparison is made with technologies typically used for these applications, i.e. heavily shielded organic scintillators for prompt neutron detection and Cd-lined {sup 3}He neutron detectors for the detection of delayed neutrons.

  8. Development of the large-area silicon PIN diode with 2 millimeter-thick depletion layer for hard x-ray detector (HXD) on board ASTRO-E

    NASA Astrophysics Data System (ADS)

    Sugizaki, Mutsumi; Kubo, S.; Murakami, Toshio; Ota, Naomi; Ozawa, Hideki; Takahashi, Tadayuki; Kaneda, Hidehiro; Iyomoto, Naoko; Kamae, Tuneyoshi; Kokubun, Motohide; Kubota, Aya; Makishima, Kazuo; Tamura, Takayuki; Tashiro, Makoto

    1997-07-01

    ASTRO-E is the next Japanese x-ray satellite to be launched in the year 2000. It carries three high-energy astrophysical experiments, including the hard x-ray detector (HXD) which is unique in covering the wide energy band from 10 keV to 700 keV with an extremely low background. The HXD is a compound-eye detector, employing 16 GSO/BGO well-type phoswich scintillation counters together with 64 silicon PIN detectors. The scintillation counters cover an energy range of 40 - 700 keV, while the PIN diodes fill the intermediate energy range from 10 keV to 70 keV with an energy resolution about 3 keV. In this paper, we report on the developments of the large area, thick silicon PIN diodes. In order to achieve a high quantum efficiency up to 70 keV with a high energy resolution, we utilize a double stack of silicon PIN diodes, each 20 by 20 mm(superscript 2) in size and 2 mm thick. Signals from the two diodes are summed into a single output. Four of these stacks (or eight diodes) are placed inside the deep BGO active-shield well of a phoswich counter, to achieve an extremely low background environment. Thus, the HXD utilizes 64 stacked silicon PIN detectors, achieving a total geometrical collecting area of 256 cm(superscript 2). We have developed the 2 mm thick silicon PIN diodes which have low leakage current, a low capacitance, and a high breakdown voltage to meet the requirements of our goal. Through various trials in fabricating PIN diodes with different structures, we have found optimal design parameters, such as mask design of the surface p(superscript +) layer and the implantation process.

  9. Gamma large area silicon telescope: Applying SI strip detector technology to the detection of gamma rays in space

    NASA Astrophysics Data System (ADS)

    Atwood, W. B.; Bloom, E. D.; Godfrey, G. L.; Hertz, P. L.; Lin, Ying-Chi; Nolan, P. L.; Snyder, A. E.; Taylor, R. E.; Wood, K. S.; Michelson, P. F.

    1992-12-01

    The recent discoveries and excitement generated by EGRET (Energetic Gamma Ray Experiment Telescope) (presently operating on CGRO (Compton Gamma Ray Observatory)) has prompted an investigation into modern technologies ultimately leading to the next generation space based gamma ray telescope. The goal is to design a detector that would increase the data acquisition rate by almost two orders of magnitude beyond EGRET, while at the same time improving on the angular resolution, the energy measurement of reconstructed gamma rays and the triggering capability of the instrument. The proposed GLAST (Gamma Ray Large Area Silicon Telescope) instrument is based on silicon particle detectors that offer the advantages of no consumables, no gas volume, robust (versus fragile), long lived, and self triggering. The GLAST detector is roughly modeled after EGRET in that a tracking module precedes a calorimeter. The GLAST tracker has planes of cross strip (x, y) 300 micrometer match silicon detectors coupled to a thin radiator to measure the coordinates of converted electron-positron pairs. An angular resolution of 0.1 deg at high energy is possible (the low energy angular resolution 100 MeV would be about 2 deg, limited by multiple scattering). The increased depth of the GLAST calorimeter over EGRET's extends the energy range to about 300 GeV.

  10. Remedial activities effectiveness verification in tailing areas.

    PubMed

    Kluson, J; Thinova, L; Neznal, M; Svoboda, T

    2015-06-01

    The complex radiological study of the basin of sludge from the uranium ore mining and preprocessing was done. Air kerma rates (including its spectral analysis) at the reference height of 1 m above ground over the whole area were measured and radiation fields mapped during two measuring campaigns (years 2009 and 2014). K, U and Th concentrations in sludge and concentrations in depth profiles (including radon concentration and radon exhalation rates) in selected points were determined using gamma spectrometry for in situ as well as laboratory samples measurement. Results were used for the analysis, design evaluation and verification of the efficiency of the remediation measures. Efficiency of the sludge basin covering by the inert material was modelled using MicroShield code. PMID:25979738

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

    SciTech Connect

    Parsai, E. Ishmael; Shvydka, Diana; Kang, Jun

    2010-08-15

    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.

  12. Using an Active Pixel Sensor In A Vertex Detector

    SciTech Connect

    Matis, Howard S.; Bieser, Fred; Chen, Yandong; Gareus, Robin; Kleinfelder, Stuart; Oldenburg, Markus; Retiere, Fabrice; Ritter, HansGeorg; Wieman, Howard H.; Wurzel, Samuel E.; Yamamoto, Eugene

    2004-04-22

    Research has shown that Active Pixel CMOS sensors can detect charged particles. We have been studying whether this process can be used in a collider environment. In particular, we studied the effect of radiation with 55 MeV protons. These results show that a fluence of about 2 x 10{sup 12} protons/cm{sup 2} reduces the signal by a factor of two while the noise increases by 25%. A measurement 6 months after exposure shows that the silicon lattice naturally repairs itself. Heating the silicon to 100 C reduced the shot noise and increased the collected charge. CMOS sensors have a reduced signal to noise ratio per pixel because charge diffuses to neighboring pixels. We have constructed a photogate to see if this structure can collect more charge per pixel. Results show that a photogate does collect charge in fewer pixels, but it takes about 15 ms to collect all of the electrons produced by a pulse of light.

  13. A universal setup for active control of a single-photon detector

    NASA Astrophysics Data System (ADS)

    Liu, Qin; Lamas-Linares, Antía; Kurtsiefer, Christian; Skaar, Johannes; Makarov, Vadim; Gerhardt, Ilja

    2014-01-01

    The influence of bright light on a single-photon detector has been described in a number of recent publications. The impact on quantum key distribution (QKD) is important, and several hacking experiments have been tailored to fully control single-photon detectors. Special attention has been given to avoid introducing further errors into a QKD system. We describe the design and technical details of an apparatus which allows to attack a quantum-cryptographic connection. This device is capable of controlling free-space and fiber-based systems and of minimizing unwanted clicks in the system. With different control diagrams, we are able to achieve a different level of control. The control was initially targeted to the systems using BB84 protocol, with polarization encoding and basis switching using beamsplitters, but could be extended to other types of systems. We further outline how to characterize the quality of active control of single-photon detectors.

  14. Investigation of a Bubble Detector based on Active Electrolocation of Weakly Electric Fish

    NASA Astrophysics Data System (ADS)

    Mohan, M.; Mayekar, K.; Zhou, R.; von der Emde, G.; Bousack, H.

    2013-04-01

    Weakly electric fish employ active electrolocation for navigation and object detection. They emit an electric signal with their electric organ in the tail and sense the electric field with electroreceptors that are distributed over their skin. We adopted this principle to design a bubble detector that can detect gas bubbles in a fluid or, in principle, objects with different electric conductivity than the surrounding fluid. The evaluation of the influence of electrode diameter on detecting a given bubble size showed that the signal increases with electrode diameter. Therefore it appears that this detector will be more appropriate for large sized applications such as bubble columns than small sized applications such as bubble detectors in dialysis.

  15. A universal setup for active control of a single-photon detector

    SciTech Connect

    Liu, Qin; Skaar, Johannes; Lamas-Linares, Antía; Kurtsiefer, Christian; Makarov, Vadim; Gerhardt, Ilja

    2014-01-15

    The influence of bright light on a single-photon detector has been described in a number of recent publications. The impact on quantum key distribution (QKD) is important, and several hacking experiments have been tailored to fully control single-photon detectors. Special attention has been given to avoid introducing further errors into a QKD system. We describe the design and technical details of an apparatus which allows to attack a quantum-cryptographic connection. This device is capable of controlling free-space and fiber-based systems and of minimizing unwanted clicks in the system. With different control diagrams, we are able to achieve a different level of control. The control was initially targeted to the systems using BB84 protocol, with polarization encoding and basis switching using beamsplitters, but could be extended to other types of systems. We further outline how to characterize the quality of active control of single-photon detectors.

  16. A universal setup for active control of a single-photon detector.

    PubMed

    Liu, Qin; Lamas-Linares, Antía; Kurtsiefer, Christian; Skaar, Johannes; Makarov, Vadim; Gerhardt, Ilja

    2014-01-01

    The influence of bright light on a single-photon detector has been described in a number of recent publications. The impact on quantum key distribution (QKD) is important, and several hacking experiments have been tailored to fully control single-photon detectors. Special attention has been given to avoid introducing further errors into a QKD system. We describe the design and technical details of an apparatus which allows to attack a quantum-cryptographic connection. This device is capable of controlling free-space and fiber-based systems and of minimizing unwanted clicks in the system. With different control diagrams, we are able to achieve a different level of control. The control was initially targeted to the systems using BB84 protocol, with polarization encoding and basis switching using beamsplitters, but could be extended to other types of systems. We further outline how to characterize the quality of active control of single-photon detectors. PMID:24517746

  17. Compilation of historical information of 300 Area facilities and activities

    SciTech Connect

    Gerber, M.S.

    1992-12-01

    This document is a compilation of historical information of the 300 Area activities and facilities since the beginning. The 300 Area is shown as it looked in 1945, and also a more recent (1985) look at the 300 Area is provided.

  18. CALIBRATION AND TESTING OF A LARGE-AREA FAST-NEUTRON DIRECTIONAL DETECTOR.

    SciTech Connect

    VANIER,P.E.

    2007-05-16

    We have developed a new directional fast-neutron detector based on double proton recoil in two separated planes of plastic scintillators with position-sensitive readout. This method allows the energy spectrum of the neutrons to be measured by a combination of peak amplitude in the first plane and time of flight to the second plane. The planes are made up of 1-m long, 10-cm high paddles with photomultipliers at both ends, so that the location of an event along the paddle can be estimated from the time delay between the optical pulses detected at the two ends. The direction of the scattered neutron can be estimated from the locations of two time-correlated events in the two planes, and the energy lost in the first scattering event can be estimated from the pulse amplitude in the first plane. The direction of the incident neutron can then be determined to lie on a cone whose angle is determined by the kinematic equations. The superposition of many such cones generates an image that indicates the presence of a localized source. Setting upper and lower limits on the time of flight allows discrimination between gamma rays, muons and neutrons. Monte Carlo simulations were performed to determine the expected angular resolution and efficiency. These models show that the lower energy limit for useful directional events is about 100 keV, because lower energy neutrons are likely to scatter more than once in the first plane. Placing a shadow bar in front of the detector provides an alternative way to obtain the direction to a point source, which may require fewer events. This method also can provide dual capability as a directional gamma detector.

  19. A Review of Accelerometry-Based Wearable Motion Detectors for Physical Activity Monitoring

    PubMed Central

    Yang, Che-Chang; Hsu, Yeh-Liang

    2010-01-01

    Characteristics of physical activity are indicative of one’s mobility level, latent chronic diseases and aging process. Accelerometers have been widely accepted as useful and practical sensors for wearable devices to measure and assess physical activity. This paper reviews the development of wearable accelerometry-based motion detectors. The principle of accelerometry measurement, sensor properties and sensor placements are first introduced. Various research using accelerometry-based wearable motion detectors for physical activity monitoring and assessment, including posture and movement classification, estimation of energy expenditure, fall detection and balance control evaluation, are also reviewed. Finally this paper reviews and compares existing commercial products to provide a comprehensive outlook of current development status and possible emerging technologies. PMID:22163626

  20. Application of a single area array detector for acquisition, tracking and point-ahead in space optical communications

    NASA Technical Reports Server (NTRS)

    Clark, D. L.; Cosgrove, M.; Van Vranken, R.; Park, H.; Fitzmaurice, M .

    1989-01-01

    Functions of acquisition, tracking, and point-ahead in space optical communications are being combined into a single system utilizing an area array detector. An analysis is presented of the feasibility concept. The key parameters are: optical power less than 1 pW at 0.86 micrometer, acquisition in less than 30 seconds in an acquisition field of view (FOV) of 1 mrad, tracking with 0.5 microrad rms noise at 1000 Hz update rate, and point ahead transfer function precision of 0.25 microrad over a region of 150 microrad. Currently available array detectors were examined. The most demanding specifications are low output noise, a high detection efficiency, a large number of pixels, and frame rates over 1kHz. A proof of concept (POC) demonstration system is currently being built utilizing the Kodak HS-40 detector (a 128 x 128 photodiode array with a 64 channel CCD readout architecture which can be operated at frame rates as high as 40,000/sec). The POC system implements a windowing scheme and special purpose digital signal processing electronic for matched filter acquisition and tracking algorithms.

  1. Probe current determination in analytical TEM/STEM and its application to the characterization of large area EDS detectors.

    PubMed

    Mitchell, David R G; Nancarrow, Mitchell J B

    2015-10-01

    A simple procedure, which enables accurate measurement of transmission electron microscopy (TEM)/STEM probe currents using an energy loss spectrometer drift tube is described. The currents obtained are compared with those measured on the fluorescent screen to enable the losses due to secondary and backscattered electrons to be determined. The current values obtained from the drift tube allow the correction of fluorescent screen current densities to yield true current. They also enable CCD conversion efficiencies to be obtained, which in turn allows images to be calibrated in terms of electron fluence. Using probes of known current in conjunction with a NiO reference specimen enables the X-ray detector solid angle to be determined. The NiO specimen also allows a wide range of other EDS detector parameters to be obtained, including the presence of ice and carbon contamination. A range of performance characteristics are reported for two large area EDS detector systems. Many of the measurements reported herein have been automated via the use of freely available scripts for DigitalMicrograph. PMID:26260274

  2. Application of a single area array detector for acquistion, tracking and point-ahead in space optical communications

    NASA Technical Reports Server (NTRS)

    Clark, D. L.; Cosgrove, M.; Vanvranken, R.; Park, H.; Fitzmaurice, M.

    1989-01-01

    Functions of acquisition, tracking, and point-ahead in space optical communications are being combined into a single system utilizing an area array detector. An analysis is presented of the feasibility concept. The key parameters are: optical power less than 1 pW at 0.86 micrometer, acquisition in less than 30 seconds in an acquisition field of view (FOV) of 1 mrad, tracking with 0.5 microrad rms noise at 1000 Hz update rate, and point ahead transfer function precision of 0.25 microrad over a region of 150 microrad. Currently available array detectors were examined. The most demanding specifications are low output noise, a high detection efficiency, a large number of pixels, and frame rates over 1kHz. A proof of concept (POC) demonstration system is currently being built utilizing the Kodak HS-40 detector (a 128 x 128 photodiode array with a 64 channel CCD readout architecture which can be operated at frame rates as high as 40,000/sec). The POC system implements a windowing scheme and special purpose digital signal processing electronic for matched filter acquisition and tracking algorithms.

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

    SciTech Connect

    Figueroa, Rodolfo; Belmar, Felipe

    2009-01-29

    This work presents an X-ray detector with fullerene C60 semi spherical geometry constituted by a set of small cylindrical proportional counter units with needles anodes, which are located in the surface of an hemispherical plastic support. The sample to be analyzed is placed on the center of the hemisphere base. The radiation may enter by one of its flanks or through the hemisphere top. The hemispherical zone that exists between the holder sample base and the proportional counters can be vacuumed, aired or filled with counter gas.

  4. Calibration of Cherenkov detectors for monoenergetic photon imaging in active interrogation applications

    NASA Astrophysics Data System (ADS)

    Rose, P. B.; Erickson, A. S.

    2015-11-01

    Active interrogation of cargo containers using monoenergetic photons offers a rapid and low-dose approach to search for shielded special nuclear materials. Cherenkov detectors can be used for imaging of the cargo provided that gamma ray energies used in interrogation are well resolved, as the case in 11B(d,n-γ)12C reaction resulting in 4.4 MeV and 15.1 MeV photons. While an array of Cherenkov threshold detectors reduces low energy background from scatter while providing the ability of high contrast transmission imaging, thus confirming the presence of high-Z materials, these detectors require a special approach to energy calibration due to the lack of resolution. In this paper, we discuss the utility of Cherenkov detectors for active interrogation with monoenergetic photons as well as the results of computational and experimental studies of their energy calibration. The results of the studies with sources emitting monoenergetic photons as well as complex gamma ray spectrum sources, for example 232Th, show that calibration is possible as long as the energies of photons of interest are distinct.

  5. Characterization of large area, thick, and segmented silicon detector for electron and proton detection from neutron beta decay experiments in the cold and ultracold energies

    NASA Astrophysics Data System (ADS)

    Salas Bacci, Americo; McGaughey, Patrick; Baessler, Stefan; Broussard, Leah; Makela, Mark; Mirabal, Jacqueline; Pattie, Robert; Pocanic, Dinko; Hoedl, Seth; Sjue, Sky; Penttila, Seppo; Hasan, Syed; Wilburn, Scott; Young, Albert; Zeck, Bryan; Wang, Zhehui

    2012-10-01

    The ``Nab'' and ``UCNB'' collaborations have proposed to measure the correlation parameters in neutron β-decay at Oak Ridge and Los Alamos National Laboratory, using a novel detector design and electromagnetic spectrometers. Two large area, thick, hexagonal-segmented Silicon detectors containing 128 pixels per detector are going to be used to detect the electron and proton from neutron decay. Both Silicon detectors are connected by magnetic field lines of few Tesla field strength, and set on an electrostatic potential, such that protons can be accelerated up to 30 keV in order to be detected. We report the characterization, operation, proton detection from 15 to 30 keV, total pulse height defect, computation of atomic scattering defect, recombination defect, and evaluation of dead layer for these large area and thick Silicon detectors.

  6. Activation of premotor vocal areas during musical discrimination.

    PubMed

    Brown, Steven; Martinez, Michael J

    2007-02-01

    Two same/different discrimination tasks were performed by amateur-musician subjects in this functional magnetic resonance imaging study: Melody Discrimination and Harmony Discrimination. Both tasks led to activations not only in classic working memory areas--such as the cingulate gyrus and dorsolateral prefrontal cortex--but in a series of premotor areas involved in vocal-motor planning and production, namely the somatotopic mouth region of the primary and lateral premotor cortices, Broca's area, the supplementary motor area, and the anterior insula. A perceptual control task involving passive listening alone to monophonic melodies led to activations exclusively in temporal-lobe auditory areas. These results show that, compared to passive listening tasks, discrimination tasks elicit activation in vocal-motor planning areas. PMID:17027134

  7. A high-speed area detector for novel imaging techniques in a scanning transmission electron microscope.

    PubMed

    Caswell, T A; Ercius, P; Tate, M W; Ercan, A; Gruner, S M; Muller, D A

    2009-03-01

    A scanning transmission electron microscope (STEM) produces a convergent beam electron diffraction pattern at each position of a raster scan with a focused electron beam, but recording this information poses major challenges for gathering and storing such large data sets in a timely manner and with sufficient dynamic range. To investigate the crystalline structure of materials, a 16x16 analog pixel array detector (PAD) is used to replace the traditional detectors and retain the diffraction information at every STEM raster position. The PAD, unlike a charge-coupled device (CCD) or photomultiplier tube (PMT), directly images 120-200keV electrons with relatively little radiation damage, exhibits no afterglow and limits crosstalk between adjacent pixels. Traditional STEM imaging modes can still be performed by the PAD with a 1.1kHz frame rate, which allows post-acquisition control over imaging conditions and enables novel imaging techniques based on the retained crystalline information. Techniques for rapid, semi-automatic crystal grain segmentation with sub-nanometer resolution are described using cross-correlation, sub-region integration, and other post-processing methods. PMID:19162398

  8. Performance of a large-area GEM detector read out with wide radial zigzag strips

    NASA Astrophysics Data System (ADS)

    Zhang, Aiwu; Bhopatkar, Vallary; Hansen, Eric; Hohlmann, Marcus; Khanal, Shreeya; Phipps, Michael; Starling, Elizabeth; Twigger, Jessie; Walton, Kimberly

    2016-03-01

    A 1-meter-long trapezoidal Triple-GEM detector with wide readout strips was tested in hadron beams at the Fermilab Test Beam Facility in October 2013. The readout strips have a special zigzag geometry and run radially with an azimuthal pitch of 1.37 mrad to measure the azimuthal ϕ-coordinate of incident particles. The zigzag geometry of the readout reduces the required number of electronic channels by a factor of three compared to conventional straight readout strips while preserving good angular resolution. The average crosstalk between zigzag strips is measured to be an acceptable 5.5%. The detection efficiency of the detector is (98.4±0.2)%. When the non-linearity of the zigzag-strip response is corrected with track information, the angular resolution is measured to be (193±3) μrad, which corresponds to 14% of the angular strip pitch. Multiple Coulomb scattering effects are fully taken into account in the data analysis with the help of a stand-alone Geant4 simulation that estimates interpolated track errors.

  9. An active drop counting device using condenser microphone for superheated emulsion detector

    SciTech Connect

    Das, Mala; Marick, C.; Kanjilal, D.; Saha, S.

    2008-11-15

    An active device for superheated emulsion detector is described. A capacitive diaphragm sensor or condenser microphone is used to convert the acoustic pulse of drop nucleation to electrical signal. An active peak detector is included in the circuit to avoid multiple triggering of the counter. The counts are finally recorded by a microprocessor based data acquisition system. Genuine triggers, missed by the sensor, were studied using a simulated clock pulse. The neutron energy spectrum of {sup 252}Cf fission neutron source was measured using the device with R114 as the sensitive liquid and compared with the calculated fission neutron energy spectrum of {sup 252}Cf. Frequency analysis of the detected signals was also carried out.

  10. Direct tests of a pixelated microchannel plate as the active element of a shower maximum detector

    DOE PAGESBeta

    Apresyan, A.; Los, S.; Pena, C.; Presutti, F.; Ronzhin, A.; Spiropulu, M.; Xie, S.

    2016-05-07

    One possibility to make a fast and radiation resistant shower maximum detector is to use a secondary emitter as an active element. We report our studies of microchannel plate photomultipliers (MCPs) as the active element of a shower-maximum detector. We present test beam results obtained using Photonis XP85011 to detect secondary particles of an electromagnetic shower. We focus on the use of the multiple pixels on the Photonis MCP in order to find a transverse two-dimensional shower distribution. A spatial resolution of 0.8 mm was obtained with an 8 GeV electron beam. As a result, a method for measuring themore » arrival time resolution for electromagnetic showers is presented, and we show that time resolution better than 40 ps can be achieved.« less

  11. Direct tests of a pixelated microchannel plate as the active element of a shower maximum detector

    NASA Astrophysics Data System (ADS)

    Apresyan, A.; Los, S.; Pena, C.; Presutti, F.; Ronzhin, A.; Spiropulu, M.; Xie, S.

    2016-08-01

    One possibility to make a fast and radiation resistant shower maximum detector is to use a secondary emitter as an active element. We report our studies of microchannel plate photomultipliers (MCPs) as the active element of a shower-maximum detector. We present test beam results obtained using Photonis XP85011 to detect secondary particles of an electromagnetic shower. We focus on the use of the multiple pixels on the Photonis MCP in order to find a transverse two-dimensional shower distribution. A spatial resolution of 0.8 mm was obtained with an 8 GeV electron beam. A method for measuring the arrival time resolution for electromagnetic showers is presented, and we show that time resolution better than 40 ps can be achieved.

  12. Use of the electrical aerosol detector as an indicator of the surface area of fine particles deposited in the lung.

    PubMed

    Wilson, William E; Stanek, John; Han, Hee-Siew Ryan; Johnson, Tim; Sakurai, Hiromu; Pui, David Y H; Turner, Jay; Chen, Da-Ren; Duthie, Scott

    2007-02-01

    Because of recent concerns about the health effects of ultrafine particles and the indication that particle toxicity is related to surface area, we have been examining techniques for measuring parameters related to the surface area of fine particles, especially in the 0.003- to 0.5-microm size range. In an earlier study, we suggested that the charge attached to particles, as measured by a prototype of the Electrical Aerosol Detector (EAD, TSI Inc., Model 3070), was related to the 1.16 power of the mobility diameter. An inspection of the pattern of particle deposition in the lung as a function of particle size suggested that the EAD measurement might be a useful indicator of the surface area of particles deposited in the lung. In this study, we calculate the particle surface area (micrometer squared) deposited in the lung per cubic centimeter of air inhaled as a function of particle size using atmospheric particle size distributions measured in Minneapolis, MN, and East St. Louis, IL. The correlations of powers of the mobility diameter, Dx, were highest for X = 1.1-1.6 for the deposited surface area and for X = 1.25 with the EAD signal. This overlap suggested a correspondence between the EAD signal and the deposited surface area. The correlation coefficients of the EAD signal and particle surface area deposited in the alveolar and tracheobronchial regions of the lung for three breathing patterns are in the range of Pearson's r = 0.91-0.95 (coefficient of determination, R2 = 0.82-0.90). These statistical relationships suggest that the EAD could serve as a useful indicator of particle surface area deposited in the lung in exposure and epidemiologic studies of the human health effects of atmospheric particles and as a measure of the potential surface area dose for the characterization of occupational environments. PMID:17355082

  13. HPGe well-type detectors for neutron activation measurements on the Frascati Tokamak Upgrade tokamak

    SciTech Connect

    Bertalot, L.; Damiani, M.; Esposito, B.; Lagamba, L.; Podda, S.; Batistoni, P.; De Felice, P.; Biagini, R.

    1997-01-01

    We describe an improvement of the neutron activation system in operation on the Frascati Tokamak Upgrade (FTU) tokamak for the measurement of the total neutron yield. A HPGe well-type detector (200 cm{sup 3} active volume) is used to detect the photoemission from neutron activated samples ({sup 115m}In336.2 keV {gamma} rays from DD neutrons on indium for FTU). Due to their high geometrical efficiency, HPGe well-type detectors are particularly suited to the FTU low-level activity measurements. A particular effort has been devoted to the calibration of the measuring system. In particular, a multi-{gamma} calibration source (59{endash}1332 keV energy range) with a density of 7.31 g/cm{sup 3} consisting of a stack of indium foils has been prepared. This assures that the shape and volume of the calibration source are the same as those of the samples used in the actual measurements. The full-energy-peak efficiency at the {sup 115m}In336.2 keV line is 0.197 with an overall uncertainty of 2{percent} (1{sigma}). For a better characterization of the detector response as a function of the sample density, a further calibration source with the same geometry has been prepared in a gel aqueous solution (density {approximately}1 g/cm{sup 3}). The calibration curves for the well-type detector at the two different density values are compared. {copyright} {ital 1997 American Institute of Physics.}

  14. A practical beryllium activation detector for measuring DD neutron yield from ICF targets

    SciTech Connect

    Murphy, T.J.

    1996-06-01

    A neutron activation detector based on the reaction {sup 9}Be(n,{alpha}){sup 6}He({beta}{sup {minus}}){sup 6}Li has been designed which could potentially allow DD yield determinations within a few minutes after an ICF implosion or other pulsed neutron event with precision comparable to methods currently in use in ICF experiments. The detector is based on previous work, but has been redesigned to allow use in a reentrant tube less than six inches in diameter, and to increase detection efficiency. The detector consists of beryllium rods imbedded in plastic scintillator and coupled to a photomultiplier tube. Neutrons interact with the beryllium to produce {sup 6}He, which decays by emission of a {beta}{sup {minus}} particle with a maximum energy of 3.51 MeV with a half life of 808 ms. The {beta}{sup {minus}} particles are counted, and a neutron yield is determined for the total activity produced. The short half life of {sup 6}He will result in high specific activity and allow quick determination of the amount of {sup 6}He produced.

  15. High-contrast X-ray micro-tomography of low attenuation samples using large area hybrid semiconductor pixel detector array of 10 × 5 Timepix chips

    NASA Astrophysics Data System (ADS)

    Karch, J.; Krejci, F.; Bartl, B.; Dudak, J.; Kuba, J.; Kvacek, J.; Zemlicka, J.

    2016-01-01

    State-of-the-art hybrid pixel semiconductor detectors provide excellent imaging properties such as unlimited dynamic range, high spatial resolution, high frame rate and energy sensitivity. Nevertheless, a limitation in the use of these devices for imaging has been the small sensitive area of a few square centimetres. In the field of microtomography we make use of a large area pixel detector assembled from 50 Timepix edgeless chips providing fully sensitive area of 14.3 × 7.15 cm2. We have successfully demonstrated that the enlargement of the sensitive area enables high-quality tomographic measurements of whole objects with high geometrical magnification without any significant degradation in resulting reconstructions related to the chip tilling and edgeless sensor technology properties. The technique of micro-tomography with the newly developed large area detector is applied for samples formed by low attenuation, low contrast materials such a seed from Phacelia tanacetifolia, a charcoalified wood sample and a beeswax seal sample.

  16. The fast neutron fluence and the activation detector activity calculations using the effective source method and the adjoint function

    SciTech Connect

    Hep, J.; Konecna, A.; Krysl, V.; Smutny, V.

    2011-07-01

    This paper describes the application of effective source in forward calculations and the adjoint method to the solution of fast neutron fluence and activation detector activities in the reactor pressure vessel (RPV) and RPV cavity of a VVER-440 reactor. Its objective is the demonstration of both methods on a practical task. The effective source method applies the Boltzmann transport operator to time integrated source data in order to obtain neutron fluence and detector activities. By weighting the source data by time dependent decay of the detector activity, the result of the calculation is the detector activity. Alternatively, if the weighting is uniform with respect to time, the result is the fluence. The approach works because of the inherent linearity of radiation transport in non-multiplying time-invariant media. Integrated in this way, the source data are referred to as the effective source. The effective source in the forward calculations method thereby enables the analyst to replace numerous intensive transport calculations with a single transport calculation in which the time dependence and magnitude of the source are correctly represented. In this work, the effective source method has been expanded slightly in the following way: neutron source data were performed with few group method calculation using the active core calculation code MOBY-DICK. The follow-up neutron transport calculation was performed using the neutron transport code TORT to perform multigroup calculations. For comparison, an alternative method of calculation has been used based upon adjoint functions of the Boltzmann transport equation. Calculation of the three-dimensional (3-D) adjoint function for each required computational outcome has been obtained using the deterministic code TORT and the cross section library BGL440. Adjoint functions appropriate to the required fast neutron flux density and neutron reaction rates have been calculated for several significant points within the RPV

  17. Mapping large areas of radioactively contaminated land with a self adapted, handheld, GPS coupled, scintillation detector.

    PubMed

    Paridaens, Johan

    2008-03-01

    In Belgium, during several decennia, a phosphate plant discharged radium chloride containing waste water into two small rivers. One of those is part of a hydrographically very complex ecosystem with lots of small tributaries and hundreds of hectares of flooding zones. Hence, the river banks and large parts of these flooding zones have become contaminated with radium, heavy metals and chlorides. During a foot campaign, using a home made portable data logging system, consisting of a commercial 2.5 kg NaI detector, a computer mouse sized GPS, and a small pocket PC, the radioactive contamination of about 600 ha of sometimes very rough terrain was measured and mapped. The resulting very detailed radium contamination maps shed a whole new light on the water flow patterns of the ecosystem. The apparatus can also be used for efficiently guiding sampling campaigns for investigating other types of contamination. The ground maps are also compared to existing maps from helicopter measurements, evaluating strengths and weaknesses from both methods. PMID:17904702

  18. Bat mortality and activity at a Northern Iowa wind resource area

    USGS Publications Warehouse

    Jain, A.A.; Koford, Rolf R.; Hancock, A.W.; Zenner, G.G.

    2011-01-01

    We examined bat collision mortality, activity and species composition at an 89-turbine wind resource area in farmland of north-central Iowa from mid-Apr. to mid-Dec., 2003 and mid-Mar. to mid-Dec., 2004. We found 30 bats beneath turbines on cleared ground and gravel access areas in 2003 and 45 bats in 2004. After adjusting for search probability, search efficiency and scavenging rate, we estimated total bat mortality at 396 ?? 72 (95 ci) in 2003 and 636 ?? 112 (95 ci) in 2004. Although carcasses were mostly migratory tree bats, we found a considerable proportion of little brown bats (Myotis lucifugus). We recorded 1465 bat echolocation call files at turbine sites ( 34.88 call files/detector-night) and 1536 bat call files at adjacent non-turbine sites ( 36.57 call files/detector-night). Bat activity did not differ significantly between turbine and non-turbine sites. A large proportion of recorded call files were made by Myotis sp. but this may be because we detected activity at ground level only. There was no relationship between types of turbine lights and either collision mortality or echolocation activity. The highest levels of bat echolocation activity and collision mortality were recorded during Jul. and Aug. during the autumn dispersal and migration period. The fatality rates for bats in general and little brown bats in particular were higher at the Top of Iowa Wind Resource Area than at other, comparable studies in the region. Future efforts to study behavior of bats in flight around turbines as well as cumulative impact studies should not ignore non-tree dwelling bats, generally regarded as minimally affected. ?? 2011, American Midland Naturalist.

  19. General formalism for the study of activation: application to radiochemical detectors

    SciTech Connect

    Poppe, C.H.

    1982-09-24

    This paper develops mathematical techniques required for the study of neutron-induced activation of importance to fission and fusion devices - reactors, nuclear weapons, etc. The formalism is presented as a guide for examining the dependence of activation products on flux time history, spatial gradients and the sensitivity to the assumed reactions and cross sections. Exact solutions in powers of the neutron fluence are presented and examined in various limits. As an example, radiochemical threshold (n,2n) detectors used to diagnose thermonuclear explosions are studied using approximations to these solutions. In particular, approximate formulas for the sensitivity of the radiochemical products to different cross sections are derived.

  20. Passive detector for measurement of the implanted (sup 210)Po activity in glass

    NASA Astrophysics Data System (ADS)

    Meesen, G.; Uyttenhove, J.; Poffijn, A.; van Laere, K.; Buysse, J.

    1994-08-01

    It is a well known fact that radon is the most important factor in the natural radiation background. For complete dose calculations we need information about the radon concentration up to 25 years ago. As suggested by C. Samuelsson et al. in 1988, the activity of the implanted radon daughter (sup 210)Po can be used to reconstruct the radon activity over the past decades. For large scale surveys in dwellings a passive detector based on polycarbonate foils has been investigated. This system has a sufficient sensitivity to detect (sup 210)Po levels down to 1 Bq/m(sup 2) with a 6 month measuring period.

  1. Logarithmic InGaAs detectors with global shutter and active dark current reduction

    NASA Astrophysics Data System (ADS)

    Ni, Yang; Arion, Bogdan; Bouvier, Christian; Noguier, Vincent

    2015-05-01

    In this paper, we present newly developed logarithmic InGaAs detectors with global shuttering and also an active dark current reduction technique to ensure ambient temperature operation without TEC for industrial applications. The newly released detectors come with both VGA (15um pitch) and QVGA (25um pitch) resolutions, giving the possibility to use lens less than 1-inch size. The logarithmic response is obtained by using solar-cell mode InGaAs photodiodes. The VGA and QVGA ROICs have 3 analog memories inside each pixel which permit, except the classic ITR, IWR and CDS modes, a new differential imaging mode which can be a useful feature in active imaging systems. The photodiode frontend circuit, in pure voltage mode, is made with non-inverting amplifier instead of CTIA. The reason of this choice is that the exposure time can be shortened without need of excessive power consumption as in CTIA front-end. We think that this arrangement associated with true CDS could match the noise performance of CTIA based one. VGA and QVGA ROICs have been designed and manufactured by using 0.18um 1P4M CMOS process. Both ROIC have been tested with success and match the design targets. The first batch of both detectors is under fabrication and will be presented during the conference.

  2. Characterization of thin p-on-p radiation detectors with active edges

    NASA Astrophysics Data System (ADS)

    Peltola, T.; Wu, X.; Kalliopuska, J.; Granja, C.; Jakubek, J.; Jakubek, M.; Härkönen, J.; Gädda, A.

    2016-03-01

    Active edge p-on-p silicon pixel detectors with thickness of 100 μm were fabricated on 150 mm float zone silicon wafers at VTT. By combining measured results and TCAD simulations, a detailed study of electric field distributions and charge collection performances as a function of applied voltage in a p-on-p detector was carried out. A comparison with the results of a more conventional active edge p-on-n pixel sensor is presented. The results from 3D spatial mapping show that at pixel-to-edge distances less than 100 μm the sensitive volume is extended to the physical edge of the detector when the applied voltage is above full depletion. The results from a spectroscopic measurement demonstrate a good functionality of the edge pixels. The interpixel isolation above full depletion and the breakdown voltage were found to be equal to the p-on-n sensor while lower charge collection was observed in the p-on-p pixel sensor below 80 V. Simulations indicated this to be partly a result of a more favourable weighting field in the p-on-n sensor and partly of lower hole lifetimes in the p-bulk.

  3. Tragaldabas: a muon ground-based detector for the study of the solar activity; first observations

    NASA Astrophysics Data System (ADS)

    José Blanco, Juan

    2016-04-01

    A new RPC-based cosmic ray detector, TRAGALDABAS (acronym of "TRAsGo for the AnaLysis of the nuclear matter Decay, the Atmosphere, the earth's B-field And the Solar activity") has been installed at the Univ. of Santiago de Compostela, Spain (N:42°52'34",W:8°33'37"). The detector, in its present layout, consists of three 1.8 m2 planes of three 1mm-gap glass RPCs. Each plane is readout with 120 pads with grounded guard electrodes between them to minimize the crosstalk noise. The main performances of the detectors are: an arrival time resolution of about ~300 ps, a tracking angular resolution below 3°, a detection efficiency close to 1, and a solid angle acceptance of ~5 srad. TRAGALDABAS will be able to monitor the cosmic ray low energy component strongly modulated by solar activity by mean the observation of secondary muons from the interaction between cosmic rays and atmospheric molecules. Its cadence and its angular resolution will allow to study in detail, small variations in cosmic ray anisotropy. These variations can be a key parameter to understand the effect of solar disturbances on the propagation of cosmic ray in the inner heliosphere and, maybe, provide a new tool for space weather analysis. In this work first TRAGALDABAS observations of solar events are shown

  4. Electrical properties of various gas mixtures for active target detector application

    NASA Astrophysics Data System (ADS)

    Yates, Daniel; Rogachev, Grigory; Koshchiy, Evgeniy; Uberseder, Ethan; Hooker, Josh

    2015-10-01

    Experiments with rare isotope beams (RIBs) open new opportunities to study properties of exotic nuclei and measure reaction cross sections relevant for nuclear astrophysics with radioactive ions. However, the low intensity of RIBs requires the development of new, more efficient detectors such as the Texas Active Target (TexAT) detector currently being developed at the Cyclotron Institute. With this detector, the target gas is also used as the active medium for tracking and energy loss measurements of charged recoils. Various gas mixtures will be used under different conditions and it is important that drift velocity and gas gain are well established. This study uses a time projection chamber with an applied electric field to measure drift velocity and electron gains of four gases to be used as targets in TexAT. The experimental values are then compared to simulation. Drift velocities of electrons were measured as a function of the electric field for each gas and pressure and then were compared to simulated values obtained from CERN's Garfield + + simulation package. The simulated and experimental drift velocities matched with root-mean-square deviations typically less than 10% for each pressure. These results provide important accuracy verification of the simulation programs and determine systematic uncertainties in track reconstructions with TexAT which rely on these simulations. Supported by NSF Grant No. 1263281.

  5. Results on a prototype of a large-area X-ray imaging device using CMOS hybrid detectors

    NASA Astrophysics Data System (ADS)

    Chaput, J.; Caria, M.; Laverroux, F.; Surre, B.; Maublant, J.

    2005-12-01

    This paper presents the first results on a prototype of a large-area X-ray imaging device made out of hybrid CMOS pixel detectors. The challenges of manufacturing and implementing imaging devices on an area larger than the single component size, with a seamless sensitive area, are addressed via a preliminary evaluation of the images. A sensitive area of approximately 6×3 cm 2 was built with eight single ASIC chips performing photon counting and bump-bonded to two high-resistivity p-n silicon sensors working in a reverse bias mode. Each chip consists of 256×256 identical square pixels of 55 μm side. The image delivered is a 1024×512-pixel matrix. Dedicated read-out electronics, software and mechanical supports have been developed. We report and discuss the challenges of the system in terms of the resulting quality of static images obtained with a 70 kV X-ray tube.

  6. Stabilization of prompt gamma-ray neutron activation analysis (PGNAA) spectra from NaI detectors

    NASA Astrophysics Data System (ADS)

    Metwally, W. A.; Gardner, R. P.

    2004-06-01

    NaI detectors are still used frequently in industrial Prompt Gamma-Ray Neutron Activation Analysis applications such as in bulk material analysis. They have the advantages of being efficient for high-energy gamma rays, being relatively rugged, and being able to be used without cooling. When using NaI detectors, and consequently photomultiplier tubes, the quality of the data can drastically deteriorate through gain and zero shifts that result in spectral smearing due to temperature and/or counting rate changes. A new offline approach is presented to stabilize the NaI spectral drift. The approach is not sensitive to the cause of the drift and takes into account the NaI and ADC non-linearities. Peak resolution is improved substantially when this approach is used in the presence of spectral drift.

  7. Performance of an improved thermal neutron activation detector for buried bulk explosives

    NASA Astrophysics Data System (ADS)

    McFee, J. E.; Faust, A. A.; Andrews, H. R.; Clifford, E. T. H.; Mosquera, C. M.

    2013-06-01

    First generation thermal neutron activation (TNA) sensors, employing an isotopic source and NaI(Tl) gamma ray detectors, were deployed by Canadian Forces in 2002 as confirmation sensors on multi-sensor landmine detection systems. The second generation TNA detector is being developed with a number of improvements aimed at increasing sensitivity and facilitating ease of operation. Among these are an electronic neutron generator to increase sensitivity for deeper and horizontally displaced explosives; LaBr3(Ce) scintillators, to improve time response and energy resolution; improved thermal and electronic stability; improved sensor head geometry to minimize spatial response nonuniformity; and more robust data processing. The sensor is described, with emphasis on the improvements. Experiments to characterize the performance of the second generation TNA in detecting buried landmines and improvised explosive devices (IEDs) hidden in culverts are described. Performance results, including comparisons between the performance of the first and second generation systems are presented.

  8. Active neutron methods for nuclear safeguards applications using Helium-4 gas scintillation detectors

    NASA Astrophysics Data System (ADS)

    Lewis, Jason M.

    Active neutron methods use a neutron source to interrogate fissionable material. In this work a 4He gas scintillation fast neutron detection system is used to measure neutrons created by the interrogation. Three new applications of this method are developed: spent nuclear fuel assay, fission rate measurement, and special nuclear material detection. Three active neutron methods are included in this thesis. First a non-destructive plutonium assay technique called Multispectral Active Neutron Interrogation Analysis is developed. It is based on interrogating fuel with neutrons at several different energies. The induced fission rates at each interrogation energy are compared with results from a neutron transport model of the irradiation geometry in a system of equations to iteratively solve the inverse problem for isotopic composition. The model is shown to converge on the correct composition for a material with 3 different fissionable components, a representative neutron absorber, and any neutron transparent material such as oxygen in a variety of geometries. Next an experimental fission rate measurement technique is developed using 4He gas scintillation fast neutron detector. Several unique features of this detector allow it to detect and provide energy information on fast neutrons with excellent gamma discrimination efficiency. The detector can measure induced fission rate by energetically differentiating between interrogation neutrons and higher energy fission neutrons. The detector response to a mono-energetic deuterium-deuterium fusion neutron generator and a 252Cf source are compared to examine the difference in detected energy range. Finally we demonstrate a special nuclear material detection technique by detecting an unambiguous fission neutron signal produced in natural uranium during active neutron interrogation using a deuterium-deuterium neutron generator and a high pressure 4He gas fast neutron scintillation detector. Energy histograms resulting from this

  9. A Novel Technique for Accurate Intensity Calibration of Area X-ray Detectors at Almost Arbitrary Energy.

    PubMed

    Moy, J P; Hammersley, A P; Svensson, S O; Thompson, A; Brown, K; Claustre, L; Gonzalez, A; McSweeney, S

    1996-01-01

    A novel intensity uniformity calibration method for area X-ray detectors is described. In diffraction experiments, amorphous lithium glass plates, containing doping elements chosen for their K edges just below the energy of the main beam, replace the crystallographic samples for the calibration measurement. The fluorescent emission excited by the X-ray beam is almost isotropic. It has exactly the same geometry as the diffracted radiation, and can be obtained at the same wavelength by proper selection of the element and excitation energy. A sample 2theta scan allows the emission distribution as a function of angle to be characterized with an accuracy of a fraction of a percent. This allows a flat-field correction of similar accuracy. The quality of crystallographic data collected with an X-ray image intensifier/CCD detector was significantly improved by flat-field correction using an Sr-doped lithium tetraborate glass. This technique can be applied to X-ray energies from 5 to 50 KeV; the calibration sample is small, stable and easily handled. PMID:16702651

  10. A Medipix quantum area detector allows rotation electron diffraction data collection from submicrometre three-dimensional protein crystals

    SciTech Connect

    Nederlof, Igor; Genderen, Eric van; Li, Yao-Wang; Abrahams, Jan Pieter

    2013-07-01

    An ultrasensitive Medipix2 detector allowed the collection of rotation electron-diffraction data from single three-dimensional protein nanocrystals for the first time. The data could be analysed using the standard X-ray crystallography programs MOSFLM and SCALA. When protein crystals are submicrometre-sized, X-ray radiation damage precludes conventional diffraction data collection. For crystals that are of the order of 100 nm in size, at best only single-shot diffraction patterns can be collected and rotation data collection has not been possible, irrespective of the diffraction technique used. Here, it is shown that at a very low electron dose (at most 0.1 e{sup −} Å{sup −2}), a Medipix2 quantum area detector is sufficiently sensitive to allow the collection of a 30-frame rotation series of 200 keV electron-diffraction data from a single ∼100 nm thick protein crystal. A highly parallel 200 keV electron beam (λ = 0.025 Å) allowed observation of the curvature of the Ewald sphere at low resolution, indicating a combined mosaic spread/beam divergence of at most 0.4°. This result shows that volumes of crystal with low mosaicity can be pinpointed in electron diffraction. It is also shown that strategies and data-analysis software (MOSFLM and SCALA) from X-ray protein crystallography can be used in principle for analysing electron-diffraction data from three-dimensional nanocrystals of proteins.

  11. Exploration Of Activity Measurements And Equilibrium Checks For Sediment Dating Using Thick-Window Germanium Detectors

    SciTech Connect

    Warner, Jacob A.; Gladkis, Laura G.; Timmers, Heiko; Fitzsimmons, Kathryn E.; Reynolds, Eva M.

    2011-06-01

    Activity measurements on sediment samples for trapped-charge geological dating using gamma-ray spectroscopy are an important verification of the field-site dose rate determination. Furthermore gamma-ray spectroscopy can check if the natural decay series are in secular equilibrium which is a crucial assumption in such dating. Typically the activities of leading members of the Thorium and Uranium decay series are measured, which requires Germanium detectors with thin windows and good energy resolution in order to effectively detect the associated low energy gamma-rays. Such equipment is not always readily available. The potential of conventional Germanium detectors with thick entrance window has been explored towards routine gamma-ray spectroscopy of sediment samples using higher energy gamma-rays. Alternative isotopes, such as Ac-228 and Pb-212 for the Thorium series, and Pa-234m, Ra-226 and Bi-214 for the Uranium series, have been measured in order to determine the mass-specific activity for the respective series and possibly provide a check of secular equilibrium. In addition to measurements of the K-40 activity, with the alternative approach, the activities of both decay series can be accurately determined. The secular equilibrium condition may be tested for the Thorium series. Measurement accuracy for Pa-234m is, however, not sufficient to permit also a reliable check of equilibrium for the Uranium series.

  12. 4H-SiC UV Photo Detector with Large Area and Very High Specific Detectivity

    NASA Technical Reports Server (NTRS)

    Yan, Feng; Shahid, Aslam; Franz, David; Xin, Xiaobin; Zhao, Jian H.; Zhao, Yuegang; Winer, Maurice

    2004-01-01

    Pt/4H-SiC Schottky photodiodes have been fabricated with the device areas up to 1 sq cm. The I-V characteristics and photo-response spectra have been measured and analyzed. For a 5 mm x 5 mm area device leakage current of 1 x 10(exp 15)A at zero bias and 1.2 x 10(exp 14)A at -IV have been established. The quantum efficiency is over 30% from 240nm to 320nm. The specific detectivity, D(sup *), has been calculated from the directly measured leakage current and quantum efficiency data and are shown to be higher than 10(exp 15) cmHz(sup 1/2)/W from 210nm to 350nm with a peak D(sup *) of 3.6 x 10(exp 15)cmH(sup 1/2)/W at 300nm.

  13. Retinal area detector from scanning laser ophthalmoscope (SLO) images for diagnosing retinal diseases.

    PubMed

    Haleem, Muhammad Salman; Han, Liangxiu; van Hemert, Jano; Li, Baihua; Fleming, Alan

    2015-07-01

    Scanning laser ophthalmoscopes (SLOs) can be used for early detection of retinal diseases. With the advent of latest screening technology, the advantage of using SLO is its wide field of view, which can image a large part of the retina for better diagnosis of the retinal diseases. On the other hand, during the imaging process, artefacts such as eyelashes and eyelids are also imaged along with the retinal area. This brings a big challenge on how to exclude these artefacts. In this paper, we propose a novel approach to automatically extract out true retinal area from an SLO image based on image processing and machine learning approaches. To reduce the complexity of image processing tasks and provide a convenient primitive image pattern, we have grouped pixels into different regions based on the regional size and compactness, called superpixels. The framework then calculates image based features reflecting textural and structural information and classifies between retinal area and artefacts. The experimental evaluation results have shown good performance with an overall accuracy of 92%. PMID:25167560

  14. Fourier analysis of the imaging characteristics of a CMOS active pixel detector for mammography by using a linearization method

    NASA Astrophysics Data System (ADS)

    Han, Jong Chul; Yun, Seungman; Youn, Hanbean; Kam, Soohwa; Cho, Seungryong; Achterkirchen, Thorsten G.; Kim, Ho Kyung

    2014-09-01

    Active pixel design using the complementary metal-oxide-semiconductor (CMOS) process is a compelling solution for use in X-ray imaging detectors because of its excellent electronic noise characteristics. We have investigated the imaging performance of a CMOS active pixel photodiode array coupled to a granular phosphor through a fiber-optic faceplate for mammographic applications. The imaging performance included the modulation-transfer function (MTF), noise-power spectrum (NPS), and detective quantum efficiency (DQE). Because we observed a nonlinear detector response at low exposures, we used the linearization method for the analysis of the DQE. The linearization method uses the images obtained at detector input, which are converted from those obtained at detector output by using the inverse of the detector response. Compared to the conventional method, the linearization method provided almost the same MTF and a slightly lower normalized NPS. However, the difference between the DQE results obtained by using the two methods was significant. We claim that the conventional DQE analysis of a detector having a nonlinear response characteristic can yield wrong results. Under the standard mammographic imaging condition, we obtained a DQE performance that was competitive with the performances of conventional flat-panel mammography detectors. We believe that the CMOS detector investigated in this study can be successfully used for mammography.

  15. Semantic Wavelet-Induced Frequency-Tagging (SWIFT) Periodically Activates Category Selective Areas While Steadily Activating Early Visual Areas

    PubMed Central

    Koenig-Robert, Roger; VanRullen, Rufin; Tsuchiya, Naotsugu

    2015-01-01

    Primate visual systems process natural images in a hierarchical manner: at the early stage, neurons are tuned to local image features, while neurons in high-level areas are tuned to abstract object categories. Standard models of visual processing assume that the transition of tuning from image features to object categories emerges gradually along the visual hierarchy. Direct tests of such models remain difficult due to confounding alteration in low-level image properties when contrasting distinct object categories. When such contrast is performed in a classic functional localizer method, the desired activation in high-level visual areas is typically accompanied with activation in early visual areas. Here we used a novel image-modulation method called SWIFT (semantic wavelet-induced frequency-tagging), a variant of frequency-tagging techniques. Natural images modulated by SWIFT reveal object semantics periodically while keeping low-level properties constant. Using functional magnetic resonance imaging (fMRI), we indeed found that faces and scenes modulated with SWIFT periodically activated the prototypical category-selective areas while they elicited sustained and constant responses in early visual areas. SWIFT and the localizer were selective and specific to a similar extent in activating category-selective areas. Only SWIFT progressively activated the visual pathway from low- to high-level areas, consistent with predictions from standard hierarchical models. We confirmed these results with criterion-free methods, generalizing the validity of our approach and show that it is possible to dissociate neural activation in early and category-selective areas. Our results provide direct evidence for the hierarchical nature of the representation of visual objects along the visual stream and open up future applications of frequency-tagging methods in fMRI. PMID:26691722

  16. Detectors for X-ray diffraction and scattering: a user's overview

    NASA Astrophysics Data System (ADS)

    Brügemann, Lutz; Gerndt, Ekkehard K. E.

    2004-09-01

    An overview of the applications of X-ray detectors to material research is given. Four experimental techniques and their specific detector requirements are described. Detector types are classified and critical parameters described in the framework of X-ray diffraction and X-ray scattering experiments. The article aims at building a bridge between detector end-users and detector developers. It gives limits of critical detector parameters, like angular resolution, energy resolution, dynamic range, and active area.

  17. CMOS Active Pixel Sensors as energy-range detectors for proton Computed Tomography

    NASA Astrophysics Data System (ADS)

    Esposito, M.; Anaxagoras, T.; Evans, P. M.; Green, S.; Manolopoulos, S.; Nieto-Camero, J.; Parker, D. J.; Poludniowski, G.; Price, T.; Waltham, C.; Allinson, N. M.

    2015-06-01

    Since the first proof of concept in the early 70s, a number of technologies has been proposed to perform proton CT (pCT), as a means of mapping tissue stopping power for accurate treatment planning in proton therapy. Previous prototypes of energy-range detectors for pCT have been mainly based on the use of scintillator-based calorimeters, to measure proton residual energy after passing through the patient. However, such an approach is limited by the need for only a single proton passing through the energy-range detector in a read-out cycle. A novel approach to this problem could be the use of pixelated detectors, where the independent read-out of each pixel allows to measure simultaneously the residual energy of a number of protons in the same read-out cycle, facilitating a faster and more efficient pCT scan. This paper investigates the suitability of CMOS Active Pixel Sensors (APSs) to track individual protons as they go through a number of CMOS layers, forming an energy-range telescope. Measurements performed at the iThemba Laboratories will be presented and analysed in terms of correlation, to confirm capability of proton tracking for CMOS APSs.

  18. SMARTPIX, a photon-counting pixel detector for synchrotron applications based on Medipix3RX readout chip and active edge pixel sensors

    NASA Astrophysics Data System (ADS)

    Ponchut, C.; Collet, E.; Hervé, C.; Le Caer, T.; Cerrai, J.; Siron, L.; Dabin, Y.; Ribois, J. F.

    2015-01-01

    Photon-counting pixel detectors are now routinely used on synchrotron beamlines. Many applications benefit from their noiseless mode of operation, single-pixel point spread function and high frame rates. One of their drawbacks is a discontinuous detection area due to the space-consuming wirebonded connections of the readout chips. Moreover, charge sharing limits their efficiency and their energy discrimination capabilities. In order to overcome these issues the ESRF is developing SMARTPIX,a scalable and versatile pixel detector system with minimized dead areas and with energy resolving capabilities based on the MEDIPIX3RX readout chip. SMARTPIX exploits the through-silicon via technology implemented on MEDIPIX3RX, the active edge sensor processing developed in particular at ADVACAM, and the on-chip analog charge summing feature of MEDIPIX3RX. This article reports on system architecture, unit module structure, data acquisition electronics, target characteristics and applications.

  19. The utilization of bubble detector technology in the development of a Combination Area Neutron Spectrometer (CANS)

    SciTech Connect

    Buckner, M.A.; Sims, C.S.

    1991-01-01

    The compact and relatively inexpensive Combination Area Neutron Spectrometer (CANS) should provide neutron spectral capabilities heretofore available only via complex set-ups and time-consuming, painstaking calculations. Some of its strong points include the measurement of neutron fluence and the need for only a single algorithm, with a single solution, regardless of the spectra. Because fluence, a real quantity, is the foundation of dose equivalent determination, the results of CANS should endure the winds of change accompanying the definition of dose equivalent and its consorted conversion conventions. It is also hoped that personnel applications may be realized in miniature version of CANS, the Personal Neutron Dosemeter/Spectrometer (PENDOSE). 6 refs., 3 figs.

  20. Prototype Active Silicon Sensor in 150 nm HR-CMOS technology for ATLAS Inner Detector Upgrade

    NASA Astrophysics Data System (ADS)

    Rymaszewski, P.; Barbero, M.; Breugnon, P.; Godiot, S.; Gonella, L.; Hemperek, T.; Hirono, T.; Hügging, F.; Krüger, H.; Liu, J.; Pangaud, P.; Peric, I.; Rozanov, A.; Wang, A.; Wermes, N.

    2016-02-01

    The LHC Phase-II upgrade will lead to a significant increase in luminosity, which in turn will bring new challenges for the operation of inner tracking detectors. A possible solution is to use active silicon sensors, taking advantage of commercial CMOS technologies. Currently ATLAS R&D programme is qualifying a few commercial technologies in terms of suitability for this task. In this paper a prototype designed in one of them (LFoundry 150 nm process) will be discussed. The chip architecture will be described, including different pixel types incorporated into the design, followed by simulation and measurement results.

  1. History of the bubble chamber and related active- and internal-target nuclear tracking detectors

    NASA Astrophysics Data System (ADS)

    Becchetti, F. D.

    2015-06-01

    Donald Glaser, 1960 Nobel laureate in Physics, recently passed away (2013), as have many of his colleagues who were involved with the early development of bubble chambers at the University of Michigan. In this paper I will review those early years and the subsequent wide-spread application of active-target (AT) bubble chambers that dominated high-energy physics (HEP) research for over thirty years. Some of the related, but more modern nuclear tracking detectors being used in HEP, neutrino astrophysics and dark-matter searches also will be discussed.

  2. Radiation Measurements Performed with Active Detectors Relevant for Human Space Exploration.

    PubMed

    Narici, Livio; Berger, Thomas; Matthiä, Daniel; Reitz, Günther

    2015-01-01

    A reliable radiation risk assessment in space is a mandatory step for the development of countermeasures and long-duration mission planning in human spaceflight. Research in radiobiology provides information about possible risks linked to radiation. In addition, for a meaningful risk evaluation, the radiation exposure has to be assessed to a sufficient level of accuracy. Consequently, both the radiation models predicting the risks and the measurements used to validate such models must have an equivalent precision. Corresponding measurements can be performed both with passive and active devices. The former is easier to handle, cheaper, lighter, and smaller but they measure neither the time dependence of the radiation environment nor some of the details useful for a comprehensive radiation risk assessment. Active detectors provide most of these details and have been extensively used in the International Space Station. To easily access such an amount of data, a single point access is becoming essential. This review presents an ongoing work on the development of a tool that allows obtaining information about all relevant measurements performed with active detectors providing reliable inputs for radiation model validation. PMID:26697408

  3. European Space Agency detector development for space science: present and future activities

    NASA Astrophysics Data System (ADS)

    Duvet, L.; Bavdaz, M.; Crouzet, P. E.; Nelms, N.; Nowicki-Bringuier, Y. R.; Shortt, B.; Verhoeve, P.

    2014-07-01

    We report on the present and future detector development activities for the European Space Agency Science Programme. The development of European technology in that field is a key mission enabler for the program, which requires TRL6 (ISO scale) by end of the definition phase, so called "mission adoption". This is particularly true for Astronomy and fundamental physics type missions. Current activities are in particular targeting large format and p-channel CCD, NIR and MWIR, LWIR wavelength ranges as well as related ASIC controller. For the longer term future mission plan (so called M4, M5 and L2 missions, M3 being PLATO and L1 JUICE), the extreme ends of the spectrum will be addressed. An overview of the detector status for the Earth Observation program is given in appendix, as most of the technologies are directly applicable to some extent to science missions, in particular for Planetary missions. The specific validation activities in place in the future mission preparation office in support to the space science program will be eventually briefly detailed.

  4. Radiation Measurements Performed with Active Detectors Relevant for Human Space Exploration

    PubMed Central

    Narici, Livio; Berger, Thomas; Matthiä, Daniel; Reitz, Günther

    2015-01-01

    A reliable radiation risk assessment in space is a mandatory step for the development of countermeasures and long-duration mission planning in human spaceflight. Research in radiobiology provides information about possible risks linked to radiation. In addition, for a meaningful risk evaluation, the radiation exposure has to be assessed to a sufficient level of accuracy. Consequently, both the radiation models predicting the risks and the measurements used to validate such models must have an equivalent precision. Corresponding measurements can be performed both with passive and active devices. The former is easier to handle, cheaper, lighter, and smaller but they measure neither the time dependence of the radiation environment nor some of the details useful for a comprehensive radiation risk assessment. Active detectors provide most of these details and have been extensively used in the International Space Station. To easily access such an amount of data, a single point access is becoming essential. This review presents an ongoing work on the development of a tool that allows obtaining information about all relevant measurements performed with active detectors providing reliable inputs for radiation model validation. PMID:26697408

  5. Defence force activities in marine protected areas: environmental management of Shoalwater Bay Training Area, Queensland, Australia

    NASA Astrophysics Data System (ADS)

    Wu, Wen; Wang, Xiaohua; Paull, David; Kesby, Julie

    2010-05-01

    Environmental management of military activities is of growing global concern by defence forces. As one of the largest landholders in Australia, the Australian Defence Force (ADF) is increasingly concerned with sustainable environmental management. This paper focuses on how the ADF is maintaining effective environmental management, especially in environmentally sensitive marine protected areas. It uses Shoalwater Bay Training Area (SWBTA) as a research example to examine environmental management strategies conducted by the ADF. SWBTA is one of the most significant Defence training areas in Australia, with a large number of single, joint and combined military exercises conducted in the area. With its maritime component contained in the Great Barrier Reef Marine Park (GBRMP), the Great Barrier Reef World Heritage Area (GBRWHA), and abutting Queensland’s State Marine Parks, it has high protection values. It is therefore vital for the ADF to adopt environmentally responsible management while they are conducting military activities. As to various tools employed to manage environmental performance, the ISO 14001 Environmental Management System (EMS) is widely used by the ADF. This paper examines military activities and marine environmental management within SWBTA, using the Talisman Saber (TS) exercise series as an example. These are extensive joint exercises conducted by the ADF and the United States defence forces. The paper outlines relevant legislative framework and environmental policies, analyses how the EMS operates in environmental management of military activities, and how military activities comply with these regulations. It discusses the implementation of the ADF EMS, including risk reduction measures, environmental awareness training, consultation and communication with stakeholders. A number of environmental management actions used in the TS exercises are presented to demonstrate the EMS application. Our investigations to this point indicate that the ADF is

  6. Adsorption of naphthenic acids on high surface area activated carbons.

    PubMed

    Iranmanesh, Sobhan; Harding, Thomas; Abedi, Jalal; Seyedeyn-Azad, Fakhry; Layzell, David B

    2014-01-01

    In oil sands mining extraction, water is an essential component; however, the processed water becomes contaminated through contact with the bitumen at high temperature, and a portion of it cannot be recycled and ends up in tailing ponds. The removal of naphthenic acids (NAs) from tailing pond water is crucial, as they are corrosive and toxic and provide a substrate for microbial activity that can give rise to methane, which is a potent greenhouse gas. In this study, the conversion of sawdust into an activated carbon (AC) that could be used to remove NAs from tailings water was studied. After producing biochar from sawdust by a slow-pyrolysis process, the biochar was physically activated using carbon dioxide (CO2) over a range of temperatures or prior to producing biochar, and the sawdust was chemically activated using phosphoric acid (H3PO4). The physically activated carbon had a lower surface area per gram than the chemically activated carbon. The physically produced ACs had a lower surface area per gram than chemically produced AC. In the adsorption tests with NAs, up to 35 mg of NAs was removed from the water per gram of AC. The chemically treated ACs showed better uptake, which can be attributed to its higher surface area and increased mesopore size when compared with the physically treated AC. Both the chemically produced and physically produced AC provided better uptake than the commercially AC. PMID:24766592

  7. Optical Detectors

    NASA Astrophysics Data System (ADS)

    Tabbert, Bernd; Goushcha, Alexander

    Optical detectors are applied in all fields of human activities from basic research to commercial applications in communication, automotive, medical imaging, homeland security, and other fields. The processes of light interaction with matter described in other chapters of this handbook form the basis for understanding the optical detectors physics and device properties.

  8. Cognitive Neurostimulation: Learning to Volitionally Sustain Ventral Tegmental Area Activation.

    PubMed

    MacInnes, Jeff J; Dickerson, Kathryn C; Chen, Nan-kuei; Adcock, R Alison

    2016-03-16

    Activation of the ventral tegmental area (VTA) and mesolimbic networks is essential to motivation, performance, and learning. Humans routinely attempt to motivate themselves, with unclear efficacy or impact on VTA networks. Using fMRI, we found untrained participants' motivational strategies failed to consistently activate VTA. After real-time VTA neurofeedback training, however, participants volitionally induced VTA activation without external aids, relative to baseline, Pre-test, and control groups. VTA self-activation was accompanied by increased mesolimbic network connectivity. Among two comparison groups (no neurofeedback, false neurofeedback) and an alternate neurofeedback group (nucleus accumbens), none sustained activation in target regions of interest nor increased VTA functional connectivity. The results comprise two novel demonstrations: learning and generalization after VTA neurofeedback training and the ability to sustain VTA activation without external reward or reward cues. These findings suggest theoretical alignment of ideas about motivation and midbrain physiology and the potential for generalizable interventions to improve performance and learning. PMID:26948894

  9. Activated carbon testing for the 200 area effluent treatment facility

    SciTech Connect

    Wagner, R.N.

    1997-01-17

    This report documents pilot and laboratory scale testing of activated carbon for use in the 200 Area Effluent Treatment Facility peroxide decomposer columns. Recommendations are made concerning column operating conditions and hardware design, the optimum type of carbon for use in the plant, and possible further studies.

  10. Activation of Premotor Vocal Areas during Musical Discrimination

    ERIC Educational Resources Information Center

    Brown, Steven; Martinez, Michael J.

    2007-01-01

    Two same/different discrimination tasks were performed by amateur-musician subjects in this functional magnetic resonance imaging study: Melody Discrimination and Harmony Discrimination. Both tasks led to activations not only in classic working memory areas--such as the cingulate gyrus and dorsolateral prefrontal cortex--but in a series of…

  11. Plasmonic lens enhanced mid-infrared quantum cascade detector

    SciTech Connect

    Harrer, Andreas Schwarz, Benedikt; Gansch, Roman; Reininger, Peter; Detz, Hermann; Zederbauer, Tobias; Andrews, Aaron Maxwell; Schrenk, Werner; Strasser, Gottfried

    2014-10-27

    We demonstrate monolithic integrated quantum cascade detectors enhanced by plasmonic lenses. Surface normal incident mid-infrared radiation is coupled to surface plasmon polaritons guided to and detected by the active region of the detector. The lens extends the optical effective active area of the device up to a 5 times larger area than for standard mesa detectors or pixel devices while the electrical active region stays the same. The extended optical area increases the absorption efficiency of the presented device as well as the room temperature performance while it offers a flexible platform for various detector geometries. A photocurrent response increase at room temperature up to a factor of 6 was observed.

  12. Results From Cs Activated GaN Photocathode Development for MCP Detector Systems at GSFC

    NASA Technical Reports Server (NTRS)

    Norton, Tim; Woodgate, Bruce; Stock, Joe; Hilton, George; Ulmer, Mel; Aslam, Shahid; Vispute, R. D.

    2003-01-01

    We describe the development of high quantum efficiency W photocathodes for use in large area two dimensional microchannel plate based detector arrays to enable new W space astronomy missions. Future W missions will require improvements in detector sensitivity, which has the most leverage for cost-effective improvements in overall telescope/instrument sensitivity. We use new materials such as p-doped GaN, AIGaN, ZnMgO, Sic and diamond. We have currently obtained QE values > 40 % at 185 nm with Cesiated GaN, and hope to demonstrate higher values in the future. By using controlled internal fields and nano-structuring of the surfaces, we plan to provide field emission assistance for photoelectrons while maintaining their energy distinction from dark noise electrons. We will transfer these methods from GaN to ZnMgO, a new family of wide band-gap materials more compatible with microchannel plates. We also are exploring technical parameters such as doping profiles, internal and external field strengths, angle of incidence, field emission assistance, surface preparation, etc.

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

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

    PubMed

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

    2016-03-01

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

  15. First OSIRIS observations of active areas on comet 67P

    NASA Astrophysics Data System (ADS)

    Vincent, J.-B.; Sierks, H.; Oklay, N.; Agarwal, J.; Güttler, C.; Bodewits, D.; Osiris Team

    2014-04-01

    After a successful exit from hibernation, Rosetta started observing its final target comet 67P in March 2014 with the two OSIRIS cameras WAC and NAC (Wide Angle and Narrow Angle Camera) [1]. By the time of this conference, the spacecraft will have flown from 5 million to 50 km from the nucleus surface, reaching a resolution of 1 meter/pixel in the NAC images. During that period, the comet heliocentric distance varies from 4.3 to 3.2 AU and we will observe how the early activity develops. We know that cometary surfaces are not fully active; only a small fraction of the surface emits gas and dust. However we do not yet understand why it happens in that way, and what to expect on 67P. Recent publications using data from ground-based telescopes have proposed different interpretations for the distribution of active sources, from one to three at various latitudes [2, 3]. There is some evidence for different levels of activity in the northern and southern hemispheres, but these variations can only be constrained with close range data. In August 2014, OSIRIS will map the surface of the comet at high resolution, and perform weekly monitoring of the activity, especially the faintest jets. With these images and the inversion code COSSIM [4], we will be able to link observed features in the coma or on the limb to physical spots on the surface. On other comets visited by spacecrafts the activity has sometimes been associated with smooth areas, rough terrains, or specific morphologic features (cliff, crater, rim, . . . ). We will present a first look at how activity and terrain are linked on 67P, and look at variations of composition, morphology, or both. We will compare this identification of active areas to previous publications.

  16. Nanosilver on nanostructured silica: Antibacterial activity and Ag surface area.

    PubMed

    Sotiriou, Georgios A; Teleki, Alexandra; Camenzind, Adrian; Krumeich, Frank; Meyer, Andreas; Panke, Sven; Pratsinis, Sotiris E

    2011-06-01

    Nanosilver is one of the first nanomaterials to be closely monitored by regulatory agencies worldwide motivating research to better understand the relationship between Ag characteristics and antibacterial activity. Nanosilver immobilized on nanostructured silica facilitates such investigations as the SiO2 support hinders the growth of nanosilver during its synthesis and, most importantly, its flocculation in bacterial suspensions. Here, such composite Ag/silica nanoparticles were made by flame spray pyrolysis of appropriate solutions of Ag-acetate or Ag-nitrate and hexamethyldisiloxane or tetraethylorthosilicate in ethanol, propanol, diethylene glucolmonobutyl ether, acetonitrile or ethylhexanoic acid. The effect of solution composition on nanosilver characteristics and antibacterial activity against the Gram negative Escherichia coli was investigated by monitoring their recombinantly synthesized green fluorescent protein. Suspensions with identical Ag mass concentration exhibited drastically different antibacterial activity pointing out that the nanosilver surface area concentration rather than its mass or molar or number concentration determine best its antibacterial activity. Nanosilver made from Ag-acetate showed a unimodal size distribution, while that made from inexpensive Ag-nitrate exhibited a bimodal one. Regardless of precursor composition or nanosilver size distribution, the antibacterial activity of nanosilver was correlated best with its surface area concentration in solution. PMID:23730198

  17. A Medipix quantum area detector allows rotation electron diffraction data collection from submicrometre three-dimensional protein crystals

    PubMed Central

    Nederlof, Igor; van Genderen, Eric; Li, Yao-Wang; Abrahams, Jan Pieter

    2013-01-01

    When protein crystals are submicrometre-sized, X-ray radiation damage precludes conventional diffraction data collection. For crystals that are of the order of 100 nm in size, at best only single-shot diffraction patterns can be collected and rotation data collection has not been possible, irrespective of the diffraction technique used. Here, it is shown that at a very low electron dose (at most 0.1 e− Å−2), a Medipix2 quantum area detector is sufficiently sensitive to allow the collection of a 30-frame rotation series of 200 keV electron-diffraction data from a single ∼100 nm thick protein crystal. A highly parallel 200 keV electron beam (λ = 0.025 Å) allowed observation of the curvature of the Ewald sphere at low resolution, indicating a combined mosaic spread/beam divergence of at most 0.4°. This result shows that volumes of crystal with low mosaicity can be pinpointed in electron diffraction. It is also shown that strategies and data-analysis software (MOSFLM and SCALA) from X-ray protein crystallography can be used in principle for analysing electron-diffraction data from three-dimensional nanocrystals of proteins. PMID:23793148

  18. A new single crystal diamond dosimeter for small beam: comparison with different commercial active detectors

    NASA Astrophysics Data System (ADS)

    Marsolat, F.; Tromson, D.; Tranchant, N.; Pomorski, M.; Le Roy, M.; Donois, M.; Moignau, F.; Ostrowsky, A.; De Carlan, L.; Bassinet, C.; Huet, C.; Derreumaux, S.; Chea, M.; Cristina, K.; Boisserie, G.; Bergonzo, P.

    2013-11-01

    Recent developments of new therapy techniques using small photon beams, such as stereotactic radiotherapy, require suitable detectors to determine the delivered dose with a high accuracy. The dosimeter has to be as close as possible to tissue equivalence and to exhibit a small detection volume compared to the size of the irradiation field, because of the lack of lateral electronic equilibrium in small beam. Characteristics of single crystal diamond (tissue equivalent material Z = 6, high density) make it an ideal candidate to fulfil most of small beam dosimetry requirements. A commercially available Element Six electronic grade synthetic diamond was used to develop a single crystal diamond dosimeter (SCDDo) with a small detection volume (0.165 mm3). Long term stability was studied by irradiating the SCDDo in a 60Co beam over 14 h. A good stability (deviation less than ± 0.1%) was observed. Repeatability, dose linearity, dose rate dependence and energy dependence were studied in a 10 × 10 cm2 beam produced by a Varian Clinac 2100 C linear accelerator. SCDDo lateral dose profile, depth dose curve and output factor (OF) measurements were performed for small photon beams with a micro multileaf collimator m3 (BrainLab) attached to the linac. This study is focused on the comparison of SCDDo measurements to those obtained with different commercially available active detectors: an unshielded silicon diode (PTW 60017), a shielded silicon diode (Sun Nuclear EDGE), a PinPoint ionization chamber (PTW 31014) and two natural diamond detectors (PTW 60003). SCDDo presents an excellent spatial resolution for dose profile measurements, due to its small detection volume. Low energy dependence (variation of 1.2% between 6 and 18 MV photon beam) and low dose rate dependence of the SCDDo (variation of 1% between 0.53 and 2.64 Gy min-1) are obtained, explaining the good agreement between the SCDDo and the efficient unshielded diode (PTW 60017) in depth dose curve measurements. For

  19. Radiation-hard active CMOS pixel sensors for HL-LHC detector upgrades

    NASA Astrophysics Data System (ADS)

    Backhaus, Malte

    2015-02-01

    The luminosity of the Large Hadron Collider (LHC) will be increased during the Long Shutdown of 2022 and 2023 (LS3) in order to increase the sensitivity of its experiments. A completely new inner detector for the ATLAS experiment needs to be developed to withstand the extremely harsh environment of the upgraded, so-called High-Luminosity LHC (HL-LHC). High radiation hardness as well as granularity is mandatory to cope with the requirements in terms of radiation damage as well as particle occupancy. A new silicon detector concept that uses commercial high voltage and/or high resistivity full complementary metal-oxide-semiconductor (CMOS) processes as active sensor for pixel and/or strip layers has risen high attention, because it potentially provides high radiation hardness and granularity and at the same time reduced price due to the commercial processing and possibly relaxed requirements for the hybridization technique. Results on the first prototypes characterized in a variety of laboratory as well as test beam environments are presented.

  20. Germanium detectors for nuclear spectroscopy: Current research and development activity at LNL

    NASA Astrophysics Data System (ADS)

    Napoli, D. R.; Maggioni, G.; Carturan, S.; Eberth, J.; Gelain, M.; Grimaldi, M. G.; Tatí, S.; Riccetto, S.; Mea, G. Della

    2016-07-01

    High-purity Germanium (HPGe) detectors have reached an unprecedented level of sophistication and are still the best solution for high-resolution gamma spectroscopy. In the present work, we will show the results of the characterization of new surface treatments for the production of these detectors, studied in the framework of our multidisciplinary research program in HPGe detector technologies.

  1. Metabolic activation of efferent pathways from the rat area postrema.

    PubMed

    Gross, P M; Wainman, D S; Shaver, S W; Wall, K M; Ferguson, A V

    1990-03-01

    We used the quantitative [14C]deoxyglucose method and autoradiography to evaluate metabolic activity in 47 individual cerebral structures or subregions that are part of neural pathways emanating from the brain stem circumventricular organ, area postrema. Electrical stimulation of the dorsocentral area postrema in halothane-ventilated rats produced hypotension and increased glucose metabolism by several structures within the ascending trajectories of efferent neural projections from the nucleus. Structures in the caudal medulla oblongata, including three subnuclei of the nucleus of the solitary tract, dorsal motor nucleus of the vagus nerve, and nucleus ambiguus-A1 noradrenergic region, had increases of metabolism during stimulation of 32-62%. Pontine activation occurred specifically in the locus coeruleus and lateral parabrachial nuclei (increases of 24-36%). Magnocellular and parvocellular subdivisions of the hypothalamic paraventricular nucleus, supraoptic and suprachiasmatic nuclei, and median eminence showed increases in metabolism of 22-34%. An 89% elevation of glucose metabolism by the pituitary neural lobe resulted. The findings are evidence for functional activation of specific structures within ascending neural pathways from area postrema to forebrain mechanisms regulating blood pressure and fluid balance. PMID:2316724

  2. Radon monitoring in groundwater samples from some areas of northern Rajasthan, India, using a RAD7 detector.

    PubMed

    Rani, Asha; Mehra, Rohit; Duggal, Vikas

    2013-01-01

    Radon monitoring has been increasingly conducted worldwide because of the hazardous effects of radon on the health of human beings. In the present research, groundwater samples were taken from hand pumps at different areas of the districts of SriGanganagar, Hanumangarh, Sikar and Churu in northern Rajasthan. RAD7, an electronic radon detector (Durridge co., USA), was used to estimate the radon concentration in groundwater used for drinking. Radon concentration in the groundwater ranged from 0.5 ± 0.3 Bq l(-1) (Chimanpura) to 85.7±4.9 Bq l(-1)(Khandela) with an average value of 9.03±1.03 Bq l(-1). In 89 % of the samples, radon concentration is well below the allowed maximum contamination level (MCL) of radon concentration in water of 11 Bq l(-1), proposed by US Environmental Protection Agency (USEPA). Only in 11 % of the samples, the recorded values were found to be higher than MCL proposed by USEPA and only in 5 % of the samples, the recorded values were found to be higher than the values between 4 and 40 Bq l(-1) suggested for radon concentration in water for human consumption by the United Nations Scientific Committee on the effect of Atomic Radiation (UNSCEAR). The annual effective dose in stomach and lungs per person was also evaluated in this research. The estimated total annual effective dose of adults ranged from 1.34 to 229.68 µSv y(-1). The total annual effective dose from three locations of the studied area was found to be greater than the safe limit (0.1 mSv y(-1)) recommended by World Health Organization and EU Council. PMID:22826356

  3. Detection systems for mass spectrometry imaging: a perspective on novel developments with a focus on active pixel detectors.

    PubMed

    Jungmann, Julia H; Heeren, Ron M A

    2013-01-15

    Instrumental developments for imaging and individual particle detection for biomolecular mass spectrometry (imaging) and fundamental atomic and molecular physics studies are reviewed. Ion-counting detectors, array detection systems and high mass detectors for mass spectrometry (imaging) are treated. State-of-the-art detection systems for multi-dimensional ion, electron and photon detection are highlighted. Their application and performance in three different imaging modes--integrated, selected and spectral image detection--are described. Electro-optical and microchannel-plate-based systems are contrasted. The analytical capabilities of solid-state pixel detectors--both charge coupled device (CCD) and complementary metal oxide semiconductor (CMOS) chips--are introduced. The Medipix/Timepix detector family is described as an example of a CMOS hybrid active pixel sensor. Alternative imaging methods for particle detection and their potential for future applications are investigated. PMID:23239313

  4. Active system area networks for data intensive computations. Final report

    SciTech Connect

    2002-04-01

    The goal of the Active System Area Networks (ASAN) project is to develop hardware and software technologies for the implementation of active system area networks (ASANs). The use of the term ''active'' refers to the ability of the network interfaces to perform application-specific as well as system level computations in addition to their traditional role of data transfer. This project adopts the view that the network infrastructure should be an active computational entity capable of supporting certain classes of computations that would otherwise be performed on the host CPUs. The result is a unique network-wide programming model where computations are dynamically placed within the host CPUs or the NIs depending upon the quality of service demands and network/CPU resource availability. The projects seeks to demonstrate that such an approach is a better match for data intensive network-based applications and that the advent of low-cost powerful embedded processors and configurable hardware makes such an approach economically viable and desirable.

  5. Active Target detectors for studies with exotic beams: Present and next future

    NASA Astrophysics Data System (ADS)

    Mittig, W.; Beceiro-Novo, S.; Fritsch, A.; Abu-Nimeh, F.; Bazin, D.; Ahn, T.; Lynch, W. G.; Montes, F.; Shore, A.; Suzuki, D.; Usher, N.; Yurkon, J.; Kolata, J. J.; Howard, A.; Roberts, A. L.; Tang, X. D.; Becchetti, F. D.

    2015-06-01

    Reaccelerated radioactive beams near the Coulomb barrier, which are starting to be available from the ReA3 accelerator at NSCL and in next future at FRIB, will open up new opportunities for the study of nuclear structure near the drip lines. Efficient measurement techniques must be developed to compensate for the limited intensity of the most exotic beams. The Active-Target Time Projection Chamber (AT-TPC) constructed at MSU solves this problem by providing the increased luminosity of a thick target while maintaining a good energy resolution by tracking the reaction vertex over an essentially 4 π solid angle. The AT-TPC and similar detectors allow us to take full advantage of the radioactive ion beams at present and future nuclear physics facilities to explore the frontier of rare isotopes.

  6. Protected areas in tropical Africa: assessing threats and conservation activities.

    PubMed

    Tranquilli, Sandra; Abedi-Lartey, Michael; Abernethy, Katharine; Amsini, Fidèle; Asamoah, Augustus; Balangtaa, Cletus; Blake, Stephen; Bouanga, Estelle; Breuer, Thomas; Brncic, Terry M; Campbell, Geneviève; Chancellor, Rebecca; Chapman, Colin A; Davenport, Tim R B; Dunn, Andrew; Dupain, Jef; Ekobo, Atanga; Eno-Nku, Manasseh; Etoga, Gilles; Furuichi, Takeshi; Gatti, Sylvain; Ghiurghi, Andrea; Hashimoto, Chie; Hart, John A; Head, Josephine; Hega, Martin; Herbinger, Ilka; Hicks, Thurston C; Holbech, Lars H; Huijbregts, Bas; Kühl, Hjalmar S; Imong, Inaoyom; Yeno, Stephane Le-Duc; Linder, Joshua; Marshall, Phil; Lero, Peter Minasoma; Morgan, David; Mubalama, Leonard; N'Goran, Paul K; Nicholas, Aaron; Nixon, Stuart; Normand, Emmanuelle; Nziguyimpa, Leonidas; Nzooh-Dongmo, Zacharie; Ofori-Amanfo, Richard; Ogunjemite, Babafemi G; Petre, Charles-Albert; Rainey, Hugo J; Regnaut, Sebastien; Robinson, Orume; Rundus, Aaron; Sanz, Crickette M; Okon, David Tiku; Todd, Angelique; Warren, Ymke; Sommer, Volker

    2014-01-01

    Numerous protected areas (PAs) have been created in Africa to safeguard wildlife and other natural resources. However, significant threats from anthropogenic activities and decline of wildlife populations persist, while conservation efforts in most PAs are still minimal. We assessed the impact level of the most common threats to wildlife within PAs in tropical Africa and the relationship of conservation activities with threat impact level. We collated data on 98 PAs with tropical forest cover from 15 countries across West, Central and East Africa. For this, we assembled information about local threats as well as conservation activities from published and unpublished literature, and questionnaires sent to long-term field workers. We constructed general linear models to test the significance of specific conservation activities in relation to the threat impact level. Subsistence and commercial hunting were identified as the most common direct threats to wildlife and found to be most prevalent in West and Central Africa. Agriculture and logging represented the most common indirect threats, and were most prevalent in West Africa. We found that the long-term presence of conservation activities (such as law enforcement, research and tourism) was associated with lower threat impact levels. Our results highlight deficiencies in the management effectiveness of several PAs across tropical Africa, and conclude that PA management should invest more into conservation activities with long-term duration. PMID:25469888

  7. Protected Areas in Tropical Africa: Assessing Threats and Conservation Activities

    PubMed Central

    Tranquilli, Sandra; Abedi-Lartey, Michael; Abernethy, Katharine; Amsini, Fidèle; Asamoah, Augustus; Balangtaa, Cletus; Blake, Stephen; Bouanga, Estelle; Breuer, Thomas; Brncic, Terry M.; Campbell, Geneviève; Chancellor, Rebecca; Chapman, Colin A.; Davenport, Tim R. B.; Dunn, Andrew; Dupain, Jef; Ekobo, Atanga; Eno-Nku, Manasseh; Etoga, Gilles; Furuichi, Takeshi; Gatti, Sylvain; Ghiurghi, Andrea; Hashimoto, Chie; Hart, John A.; Head, Josephine; Hega, Martin; Herbinger, Ilka; Hicks, Thurston C.; Holbech, Lars H.; Huijbregts, Bas; Kühl, Hjalmar S.; Imong, Inaoyom; Yeno, Stephane Le-Duc; Linder, Joshua; Marshall, Phil; Lero, Peter Minasoma; Morgan, David; Mubalama, Leonard; N'Goran, Paul K.; Nicholas, Aaron; Nixon, Stuart; Normand, Emmanuelle; Nziguyimpa, Leonidas; Nzooh-Dongmo, Zacharie; Ofori-Amanfo, Richard; Ogunjemite, Babafemi G.; Petre, Charles-Albert; Rainey, Hugo J.; Regnaut, Sebastien; Robinson, Orume; Rundus, Aaron; Sanz, Crickette M.; Okon, David Tiku; Todd, Angelique; Warren, Ymke; Sommer, Volker

    2014-01-01

    Numerous protected areas (PAs) have been created in Africa to safeguard wildlife and other natural resources. However, significant threats from anthropogenic activities and decline of wildlife populations persist, while conservation efforts in most PAs are still minimal. We assessed the impact level of the most common threats to wildlife within PAs in tropical Africa and the relationship of conservation activities with threat impact level. We collated data on 98 PAs with tropical forest cover from 15 countries across West, Central and East Africa. For this, we assembled information about local threats as well as conservation activities from published and unpublished literature, and questionnaires sent to long-term field workers. We constructed general linear models to test the significance of specific conservation activities in relation to the threat impact level. Subsistence and commercial hunting were identified as the most common direct threats to wildlife and found to be most prevalent in West and Central Africa. Agriculture and logging represented the most common indirect threats, and were most prevalent in West Africa. We found that the long-term presence of conservation activities (such as law enforcement, research and tourism) was associated with lower threat impact levels. Our results highlight deficiencies in the management effectiveness of several PAs across tropical Africa, and conclude that PA management should invest more into conservation activities with long-term duration. PMID:25469888

  8. Power and area efficient 4-bit column-level ADC in a CMOS pixel sensor for the ILD vertex detector

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Morel, F.; Hu-Guo, Ch; Hu, Y.

    2013-01-01

    A 48 × 64 pixels prototype CMOS pixel sensor (CPS) integrated with 4-bit column-level, self triggered ADCs for the outer layers of the ILD vertex detector (VTX) was developed and fabricated in a 0.35 μm CMOS process with a pixel pitch of 35 μm. The pixel concept combines in-pixel amplification with a correlated double sampling (CDS) operation. The ADCs accommodating the pixel read out in a rolling shutter mode complete the conversion by performing a multi-bit/step approximation. The design was optimised for power saving at sampling frequency. The prototype sensor is currently at the stage of being started testing and evaluation. So what is described is based on post simulation results rather than test data. This 4-bit ADC dissipates, at a 3-V supply and 6.25-MS/s sampling rate, 486 μW in its inactive mode, which is by far the most frequent. This value rises to 714 μW in case of the active mode. Its footprint amounts to 35 × 545 μm2.

  9. ILO activities in the area of chemical safety.

    PubMed

    Obadia, Isaac

    2003-08-21

    The ILO has been active in the area of safety in the use of chemicals at work since the year of its creation in 1919, including the development of international treaties and other technical instruments, the provision of technical assistance to its member States, and the development of chemical safety information systems. The two key ILO standards in this area are the Conventions on safety in the use of chemicals at work (No. 170, 1990), and the Prevention of Major Industrial Accidents (No. 174, 1993). The ILO Programme on occupational safety, health and environment (Safe Work) is currently responsible for ILO chemical safety activities. In the past two decades, most of ILO work in this area has been carried out within the context of inter-agency collaboration frameworks linking the ILO, WHO, UNEP, FAO, UNIDO, UNITAR, and the OECD, including the International Programme on Chemical Safety (IPCS), the Inter-Organisation Programme for the Sound Management of Chemicals (IOMC), and the Intergovernmental Forum on Chemical Safety (IFCS). Apart from the regular development, updating and dissemination of chemical safety information data bases such as the IPCS International Chemical Cards, the elaboration of a Globally harmonized system for the classification and labelling of Chemicals (GHS) has been the most outstanding achievement of this international collaboration on chemical safety. PMID:12909402

  10. CBM in the vicinity of active mining areas

    NASA Astrophysics Data System (ADS)

    Hölscher, Gerhard

    2010-05-01

    In areas close to operating mines, optional CBM operations meet several advantages. Any consideration about CBM operations close to active or ex-mining areas can rely on a lot of existing knowledge from the nearby mine regarding Geological data: seam thickness and structure, rock structure and composition, overburden setup Structural data: fault system, fault style, Stratigraphic informations: seam and adjacent rock stratigraphic identification Petrographic data: coal composition data Coal quality data: heating values, volatile matter, maturity, gas contents which approximately correspond to the respective data sets of the adjacent mine. As well and of importance for drilling issues the knowledge from former exploration measure can be adapted. Permeability is not transferable between mined and un-mined areas due to higher stream for gaseous and liquid matter in mining areas as a result of mining induced rock disaggregation. However, the vicinity permits the option of drilling operations for CBM purposes from the open subsurface architecture. Experiences in the USA and in India document the application of CBM projects for coal mine degassing: in mining fields adjacent to future coal mining, the gas content is severely reduced by CBM measures prior to mining. As a result of that, subsequent to CBM operations a mine can be run at reduced gas content to be emitted which means higher mine safety. At least the production potential will be increased as e.g. the gas alert driven power interruptions will be reduced.

  11. 3D IC for Future HEP Detectors

    SciTech Connect

    Thom, J.; Lipton, R.; Heintz, U.; Johnson, M.; Narain, M.; Badman, R.; Spiegel, L.; Triphati, M.; Deptuch, G.; Kenney, C.; Parker, S.; Ye, Z.; Siddons, D.

    2014-11-07

    Three dimensional integrated circuit technologies offer the possibility of fabricating large area arrays of sensors integrated with complex electronics with minimal dead area, which makes them ideally suited for applications at the LHC upgraded detectors and other future detectors. Here we describe ongoing R&D efforts to demonstrate functionality of components of such detectors. This also includes the study of integrated 3D electronics with active edge sensors to produce "active tiles" which can be tested and assembled into arrays of arbitrary size with high yield.

  12. 3D IC for future HEP detectors

    NASA Astrophysics Data System (ADS)

    Thom, J.; Lipton, R.; Heintz, U.; Johnson, M.; Narain, M.; Badman, R.; Spiegel, L.; Triphati, M.; Deptuch, G.; Kenney, C.; Parker, S.; Ye, Z.; Siddons, D. P.

    2014-11-01

    Three dimensional integrated circuit technologies offer the possibility of fabricating large area arrays of sensors integrated with complex electronics with minimal dead area, which makes them ideally suited for applications at the LHC upgraded detectors and other future detectors. We describe ongoing R&D efforts to demonstrate functionality of components of such detectors. This includes the study of integrated 3D electronics with active edge sensors to produce "active tiles" which can be tested and assembled into arrays of arbitrary size with high yield.

  13. Well completion practices in active U. S. areas

    SciTech Connect

    Not Available

    1980-05-01

    This work presents results of field visits and meetings with oil companies and independent operators to determine the latest in drilling and well completion practices in active US areas. Those areas and practices include S. Texas (operations to control annular gas flow during cementing); offshore Texas (rapidly changing pressure gradients require numerous casing strings); Cotton Valley (large sandstone frac jobs); Sonora Basin (smaller, low-rate fracturing); W. Texas (minor Permian basin infill drilling problems); Tuscaloosa trend (drilling operations planned around pressure transition zones); offshore Louisiana (geology and directional work complicate drilling); Overthrust Belt (abnormally low pressure zones and hydrogen sulfide problems); Williston basin (logistics problems); and California (well designs used for steam stimulated production).

  14. Parallel Configuration For Fast Superconducting Strip Line Detectors With Very Large Area In Time Of Flight Mass Spectrometry

    SciTech Connect

    Casaburi, A.; Zen, N.; Suzuki, K.; Ohkubo, M.; Ejrnaes, M.; Cristiano, R.; Pagano, S.

    2009-12-16

    We realized a very fast and large Superconducting Strip Line Detector based on a parallel configuration of nanowires. The detector with size 200x200 {mu}m{sup 2} recorded a sub-nanosecond pulse width of 700 ps in FWHM (400 ps rise time and 530 ps relaxation time) for lysozyme monomers/multimers molecules accelerated at 175 keV in a Time of Flight Mass Spectrometer. This record is the best in the class of superconducting detectors and comparable with the fastest NbN superconducting single photon detector of 10x10 {mu}m{sup 2}. We succeeded in acquiring mass spectra as the first step for a scale-up to {approx}mm pixel size for high throughput MS analysis, while keeping a fast response.

  15. Semiconductor radiation detector

    DOEpatents

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

    2002-01-01

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

  16. The Dexela 2923 CMOS X-ray detector: A flat panel detector based on CMOS active pixel sensors for medical imaging applications

    NASA Astrophysics Data System (ADS)

    Konstantinidis, Anastasios C.; Szafraniec, Magdalena B.; Speller, Robert D.; Olivo, Alessandro

    2012-10-01

    Complementary metal-oxide-semiconductors (CMOS) active pixel sensors (APS) have been introduced recently in many scientific applications. This work reports on the performance (in terms of signal and noise transfer) of an X-ray detector that uses a novel CMOS APS which was developed for medical X-ray imaging applications. For a full evaluation of the detector's performance, electro-optical and X-ray characterizations were carried out. The former included measuring read noise, full well capacity and dynamic range. The latter, which included measuring X-ray sensitivity, presampling modulation transfer function (pMTF), noise power spectrum (NPS) and the resulting detective quantum efficiency (DQE), was assessed under three beam qualities (28 kV, 50 kV (RQA3) and 70 kV (RQA5) using W/Al) all in accordance with the IEC standard. The detector features an in-pixel option for switching the full well capacity between two distinct modes, high full well (HFW) and low full well (LFW). Two structured CsI:Tl scintillators of different thickness (a “thin” one for high resolution and a thicker one for high light efficiency) were optically coupled to the sensor array to optimize the performance of the system for different medical applications. The electro-optical performance evaluation of the sensor results in relatively high read noise (∼360 e-), high full well capacity (∼1.5×106 e-) and wide dynamic range (∼73 dB) under HFW mode operation. When the LFW mode is used, the read noise is lower (∼165) at the expense of a reduced full well capacity (∼0.5×106 e-) and dynamic range (∼69 dB). The maximum DQE values at low frequencies (i.e. 0.5 lp/mm) are high for both HFW (0.69 for 28 kV, 0.71 for 50 kV and 0.75 for 70 kV) and LFW (0.69 for 28 kV and 0.7 for 50 kV) modes. The X-ray performance of the studied detector compares well to that of other mammography and general radiography systems, obtained under similar experimental conditions. This demonstrates the suitability

  17. Three-element trap filter radiometer based on large active area silicon photodiodes.

    PubMed

    Salim, S G R; Anhalt, K; Taubert, D R; Hollandt, J

    2016-05-20

    This paper shows the opto-mechanical design of a new filter radiometer built at the Physikalisch-Technische Bundesanstalt, Germany, for the accurate determination of the thermodynamic temperature of high-temperature blackbodies. The filter radiometer is based on a three-element reflection-type trap detector that uses three large active area silicon photodiodes. Its spectral coverage and field of view are defined by a detachable narrow-band filter and a diamond-turned precision aperture, respectively. The temperature of the filter radiometer is stabilized using a water-streamed housing and is measured using a thin-film platinum thermometer placed onto the first photodiode element. The trap "mount" has been made as compact as possible, which, together with the large active area of the chosen photodiodes, allows a wide field of view. This work presents the design of the filter radiometer and discusses the criteria that have been considered in order for the filter radiometer to suit the application. PMID:27411121

  18. The Timing of Noise-Sensitive Activities in Residential Areas

    NASA Technical Reports Server (NTRS)

    Fields, J. M.

    1985-01-01

    Data from a nationally representative survey of time use was analyzed to provide estimates of the percentage of the population which is engaged in noise sensitive activities during each hour of the day on weekdays, Fridays, Saturdays and Sundays. Estimates are provided of the percentage engaged in aural communication activities at home, sleeping at home, or simply at home. The day can be roughly divided into four noise sensitivity periods consisting of two relatively steady state periods, night and day and the early morning and evening transition periods. Weekends differ from weekdays in that the morning transition period is one hour later and the numbers of people engaged in aural communication during the day at home are approximately one-half to three-quarters greater. The extent and timing of noise sensitive activities was found to be similiar for all parts of the United States, for different sizes of urban areas, and for the three seasons surveyed (September through May). The timing of activity periods does not differ greatly by sex or age even though women and people over 65 are much more likely to be at home during the daytime.

  19. Brainstem areas activated by intermittent apnea in awake unrestrained rats.

    PubMed

    Ferreira, C B; Schoorlemmer, G H; Rossi, M V; Takakura, A C; Barna, B F; Moreira, T S; Cravo, S L

    2015-06-25

    We investigated the role of the autonomic nervous system to cardiovascular responses to obstructive apnea in awake, unrestrained rats, and measured expression of Fos induced by apnea in the brainstem. We implanted a tracheal balloon contained in a rigid tube to allow the induction of apnea without inducing pain in the trachea. During bouts of 15s of apnea, heart rate fell from 371±8 to 161±11bpm (mean±SEM, n=15, p<0.01) and arterial pressure increased from 115±2 to 131±4mmHg (p<0.01). Bradycardia was due to parasympathetic activity because it was blocked by the muscarinic antagonist, methylatropine. The pressor response was due to vasoconstriction caused by sympathetic activation because it was blocked by the α1 antagonist, prazosin. Apnea induced Fos expression in several brainstem areas involved in cardiorespiratory control such as the nucleus of the solitary tract (NTS), ventrolateral medulla (VLM), and pons. Ligation of the carotid body artery reduced apnea-induced bradycardia, blocked heart rate responses to i.v. injection of cyanide, reduced Fos expression in the caudal NTS, and increased Fos expression in the rostral VLM. In conclusion, apnea activates neurons in regions that process signals from baroreceptors, chemoreceptors, pulmonary receptors, and regions responsible for autonomic and respiratory activity both in the presence and absence of carotid chemoreceptors. PMID:25862588

  20. The timing of noise-sensitive activities in residential areas

    NASA Astrophysics Data System (ADS)

    Fields, J. M.

    1985-07-01

    Data from a nationally representative survey of time use was analyzed to provide estimates of the percentage of the population which is engaged in noise sensitive activities during each hour of the day on weekdays, Fridays, Saturdays and Sundays. Estimates are provided of the percentage engaged in aural communication activities at home, sleeping at home, or simply at home. The day can be roughly divided into four noise sensitivity periods consisting of two relatively steady state periods, night and day and the early morning and evening transition periods. Weekends differ from weekdays in that the morning transition period is one hour later and the numbers of people engaged in aural communication during the day at home are approximately one-half to three-quarters greater. The extent and timing of noise sensitive activities was found to be similiar for all parts of the United States, for different sizes of urban areas, and for the three seasons surveyed (September through May). The timing of activity periods does not differ greatly by sex or age even though women and people over 65 are much more likely to be at home during the daytime.

  1. Characterization of Depleted Monolithic Active Pixel detectors implemented with a high-resistive CMOS technology

    NASA Astrophysics Data System (ADS)

    Kishishita, T.; Hemperek, T.; Rymaszewski, P.; Hirono, T.; Krüger, H.; Wermes, N.

    2016-07-01

    We present the recent development of DMAPS (Depleted Monolithic Active Pixel Sensor), implemented with a Toshiba 130 nm CMOS process. Unlike in the case of standard MAPS technologies which are based on an epi-layer, this process provides a high-resistive substrate that enables larger signal and faster charge collection by drift in a 50 - 300 μm thick depleted layer. Since this process also enables the use of deep n-wells to isolate the collection electrodes from the thin active device layer, NMOS and PMOS transistors are available for the readout electronics in each pixel cell. In order to characterize the technology, we implemented a simple three transistor readout with a variety of pixel pitches and input FET sizes. This layout variety gives us a clue on sensor characteristics for future optimization, such as the input detector capacitance or leakage current. In the initial measurement, the radiation spectra were obtained from 55Fe with an energy resolution of 770 eV (FWHM) and 90Sr with the MVP of 4165 e-.

  2. Active pixels of transverse field detector based on a charge preamplifier

    NASA Astrophysics Data System (ADS)

    Langfelder, G.; Buffa, C.; Longoni, A. F.; Pelamatti, A.; Zaraga, F.

    2012-01-01

    The Transverse Field Detector (TFD), a filter-less and tunable color sensitive pixel, is based on the generation of specific electric field configurations within a depleted Silicon volume. Each field configuration determines a set of three or more spectral responses that can be used for direct color acquisition at each pixel position. In order to avoid unpredictable changes of the electric field configuration during the single image capture, a specific active pixel (AP) has been designed. In this AP the dark- and photo-generated charge is not integrated directly on the junction capacitance, but, for each color, it is integrated on the feedback capacitance of a single-transistor charge pre-amplifier. The AP further includes a bias transistor, a reset transistor and a follower. In this work the design of such a pixel is discussed and the experimental results obtained on a 2x2 matrix of these active pixels are analyzed in terms of spectral response, linearity, noise, dynamic range and repeatability.

  3. Gamma Large Area Silicon Telescope (GLAST): Applying silicon strip detector technology to the detection of gamma rays in space

    SciTech Connect

    Atwood, W.B.; The GLAST Collaboration

    1993-06-01

    The recent discoveries and excitement generated by space satellite experiment EGRET (presently operating on Compton Gamma Ray Observatory -- CGRO) have prompted an investigation into modern detector technologies for the next generation space based gamma ray telescopes. The GLAST proposal is based on silicon strip detectors as the {open_quotes}technology of choice{close_quotes} for space application: no consumables, no gas volume, robust (versus fragile), long lived, and self triggerable. The GLAST detector basically has two components: a tracking module preceding a calorimeter. The tracking module has planes of crossed strip (x,y) 300 {mu}m pitch silicon detectors coupled to a thin radiator to measure the coordinates of converted electron-positron pairs. The gap between the layers ({approximately}5 cm) provides a lever arm for track fitting resulting in an angular resolution of <0.1{degree} at high energy. The status of this R & D effort is discussed including details on triggering the instrument, the organization of the detector electronics and readout, and work on computer simulations to model this instrument.

  4. 3He neutron detector design for active detection of cargo containers

    NASA Astrophysics Data System (ADS)

    McDevitt, Daniel B.; Eberhard, J. W.; Zelakiewicz, Scott; Maschinot, Aaron

    2008-04-01

    We report on the design of a neutron detector using industry standard 3He tubes to count delayed neutrons during the interrogation of cargo containers for the presence of Special Nuclear Material (SNM). Simulations of the detector design were run for delayed neutron spectra for a variety of cargos containing SNM using the Monte Carlo computer code COG. The simulations identified parameters crucial to optimize the detector design. These choices include moderating material type and thickness, tube spacing, tube pressure and number of tubes. An experimental prototype was also constructed based on the simulated design specifications. This paper discusses the parameters that lead up to the optimized detector design. It also compares the performance of the Monte Carlo simulated design and the experimental detector when exposed to a 239Pu-Be source.

  5. Performance in test beam of a large-area and light-weight GEM detector with 2D stereo-angle (U-V) strip readout

    NASA Astrophysics Data System (ADS)

    Gnanvo, Kondo; Bai, Xinzhan; Gu, Chao; Liyanage, Nilanga; Nelyubin, Vladimir; Zhao, Yuxiang

    2016-02-01

    A large-area and light-weight gas electron multiplier (GEM) detector was built at the University of Virginia as a prototype for the detector R&D program of the future Electron Ion Collider. The prototype has a trapezoidal geometry designed as a generic sector module in a disk layer configuration of a forward tracker in collider detectors. It is based on light-weight material and narrow support frames in order to minimize multiple scattering and dead-to-sensitive area ratio. The chamber has a novel type of two dimensional (2D) stereo-angle readout board with U-V strips that provides (r,φ) position information in the cylindrical coordinate system of a collider environment. The prototype was tested at the Fermilab Test Beam Facility in October 2013 and the analysis of the test beam data demonstrates an excellent response uniformity of the large area chamber with an efficiency higher than 95%. An angular resolution of 60 μrad in the azimuthal direction and a position resolution better than 550 μm in the radial direction were achieved with the U-V strip readout board. The results are discussed in this paper.

  6. Development of a New Fast Shower Maximum Detector Based on Microchannel Plates Photomultipliers (MCP-PMT) as an Active Element

    SciTech Connect

    Ronzhin, A.; Los, S.; Ramberg, E.; Spiropulu, M.; Apresyan, A.; Xie, S.; Kim, H.; Zatserklyaniy, A.

    2014-09-21

    One possibility to make a fast and radiation resistant shower maximum (SM) detector is to use a secondary emitter as an active element. We present below test beam results, obtained with different types of photodetectors based on microchannel plates (MCPs) as the secondary emitter. We performed the measurements at the Fermilab Test Beam Facility with 120GeV proton beam and 12GeV and 32GeV secondary beams. The goal of the measurement with 120GeV protons was to determine time resolution for minimum ionizing particles (MIPs). The SM time resolution we obtained for this new type of detector is at the level of 20-30ps. We estimate that a significant contribution to the detector response originates from secondary emission of the MCP. This work can be considered as the first step in building a new type of calorimeter based on this principle.

  7. Active quenching and gating circuit of the photon counting detector for laser time transfer with improved timing resolution and stability

    NASA Astrophysics Data System (ADS)

    Prochazka, Ivan; Blazej, Josef; Kodet, Jan; Michalek, Vojtech

    2015-05-01

    We are presenting the results of research and development of a new active quenching and gating electronics for Single Photon Avalanche Detector (SPAD). The goal of the work was to develop a new SPAD detector package for Laser Time Transfer ground to space with improved timing resolution and stability. The first version of a SPAD detector is operational on board of GNSS navigation satellites. They are based on 25 μm diameter K14 series SPAD chips. They do provide timing resolution of typically 125 ps and stability of the order of 10 ps. The new control electronics provides timing resolution of 25 ps and timing stability and drifts of the order of one picosecond. The device is constructed on a basis of electronics components for which the space qualified equivalents are commercially available. The device construction, tests and results will be presented in detail.

  8. Development of a new fast shower maximum detector based on microchannel plates photomultipliers (MCP-PMT) as an active element

    NASA Astrophysics Data System (ADS)

    Ronzhin, A.; Los, S.; Ramberg, E.; Spiropulu, M.; Apresyan, A.; Xie, S.; Kim, H.; Zatserklyaniy, A.

    2014-09-01

    One possibility to make a fast and radiation resistant shower maximum (SM) detector is to use a secondary emitter as an active element. We present below test beam results, obtained with different types of photodetectors based on microchannel plates (MCPs) as the secondary emitter. We performed the measurements at the Fermilab Test Beam Facility with 120 GeV proton beam and 12 GeV and 32 GeV secondary beams. The goal of the measurement with 120 GeV protons was to determine time resolution for minimum ionizing particles (MIPs). The SM time resolution we obtained for this new type of detector is at the level of 20-30 ps. We estimate that a significant contribution to the detector response originates from secondary emission of the MCP. This work can be considered as the first step in building a new type of calorimeter based on this principle.

  9. Active Fault Characterization in the Urban Area of Vienna

    NASA Astrophysics Data System (ADS)

    Decker, Kurt; Grupe, Sabine; Hintersberger, Esther

    2016-04-01

    The identification of active faults that lie beneath a city is of key importance for seismic hazard assessment. Fault mapping and characterization in built-up areas with strong anthropogenic overprint is, however, a challenging task. Our study of Quaternary faults in the city of Vienna starts from the re-assessment of a borehole database of the municipality containing several tens of thousands of shallow boreholes. Data provide tight constraints on the geometry of Quaternary deposits and highlight several locations with fault-delimited Middle to Late Pleistocene terrace sediments of the Danube River. Additional information is obtained from geological descriptions of historical outcrops which partly date back to about 1900. The latter were found to be particularly valuable by providing unprejudiced descriptions of Quaternary faults, sometimes with stunning detail. The along-strike continuations of some of the identified faults are further imaged by industrial 2D/3D seismic acquired outside the city limits. The interpretation and the assessment of faults identified within the city benefit from a very well constrained tectonic model of the active Vienna Basin fault system which derived from data obtained outside the city limits. This data suggests that the urban faults are part of a system of normal faults compensating fault-normal extension at a releasing bend of the sinistral Vienna Basin Transfer Fault. Slip rates estimated for the faults in the city are in the range of several hundredths of millimetres per year and match the slip rates of normal faults that were trenched outside the city. The lengths/areas of individual faults estimated from maps and seismic reach up to almost 700 km² suggesting that all of the identified faults are capable of producing earthquakes with magnitudes M>6, some with magnitudes up to M~6.7.

  10. Cholinesterase activity per unit surface area of conducting membranes.

    PubMed

    Brzin, M; Dettbarn, W D; Rosenberg, P; Nachmansohn, D

    1965-08-01

    According to theory, the action of acetylcholine (ACh) and ACh-esterase is essential for the permeability changes of excitable membranes during activity. It is, therefore, pertinent to know the activity of ACh-esterase per unit axonal surface area instead of per gram nerve, as it has been measured in the past. Such information has now been obtained with the newly developed microgasometric technique using a magnetic diver. (1) The cholinesterase (Ch-esterase) activity per mm(2) surface of sensory axons of the walking leg of lobster is 1.2 x 10(-3) microM/hr. (sigma = +/- 0.3 x 10(-3); SE = 0.17 x 10(-3)); the corresponding value for the motor axons isslightly higher: 1.93 x 10(-3) microM/hr. (sigma = +/- 0.41 x 10(-3); SE = +/- 0.14 x 10(-3)). Referred to gram nerve, the Ch-esterase activity of the sensory axons is much higher than that of the motor axons: 741 microM/hr. (sigma = +/- 73.5; SE = +/- 32.6) versus 111.6 microM/hr. (sigma = +/- 28.3; SE = +/- 10). (2) The enzyme activity in the small fibers of the stellar nerve of squid is 3.2 x 10(-4) microM/mm(2)/hr. (sigma = +/- 0.96 x 10(-4); SE = +/- 0.4 x 10(-4)). (3) The Ch-esterase activity per mm(2) surface of squid giant axon is 9.5 x 10(-5) microM/hr. (sigma = +/- 1.55 x 10(-5); SE = +/- 0.38 x 10(-5)). The value was obtained with small pieces of carefully cleaned axons after removal of the axoplasm and exposure to sonic disintegration. Without the latter treatment the figurewas 3.85 x 10(-5) microM/mm(2)/hr. (sigma = +/- 3.24 x 10(-5); SE = +/- 0.93 x 10(-5)). The experiments indicate the existence of permeability barriers in the cell wall surrounding part of the enzyme, since the substrate cannot reach all the enzyme even when small fragments of the cell wall are used without disintegration. (4) On the basis of the data obtained, some tentative approximations are made of the ratio of ACh released to Na ions entering the squid giant axon per cm(2) per impulse. PMID:5865929

  11. Electron-phonon interaction in three-barrier nanosystems as active elements of quantum cascade detectors

    SciTech Connect

    Tkach, N. V. Seti, Ju. A.; Grynyshyn, Yu. B.

    2015-04-15

    The theory of electron tunneling through an open nanostructure as an active element of a quantum cascade detector is developed, which takes into account the interaction of electrons with confined and interface phonons. Using the method of finite-temperature Green’s functions and the electron-phonon Hamiltonian in the representation of second quantization over all system variables, the temperature shifts and electron-level widths are calculated and the contributions of different electron-phonon-interaction mechanisms to renormalization of the spectral parameters are analyzed depending on the geometrical configuration of the nanosystem. Due to weak electron-phonon coupling in a GaAs/Al{sub 0.34}Ga{sub 0.66}As-based resonant tunneling nanostructure, the temperature shift and rf field absorption peak width are not very sensitive to the electron-phonon interaction and result from a decrease in potential barrier heights caused by a difference in the temperature dependences of the well and barrier band gaps.

  12. Hypothetical and real choice differentially activate common valuation areas.

    PubMed

    Kang, Min Jeong; Rangel, Antonio; Camus, Mickael; Camerer, Colin F

    2011-01-12

    Hypothetical reports of intended behavior are commonly used to draw conclusions about real choices. A fundamental question in decision neuroscience is whether the same type of valuation and choice computations are performed in hypothetical and real decisions. We investigated this question using functional magnetic resonance imaging while human subjects made real and hypothetical choices about purchases of consumer goods. We found that activity in common areas of the orbitofrontal cortex and the ventral striatum correlated with behavioral measures of the stimulus value of the goods in both types of decision. Furthermore, we found that activity in these regions was stronger in response to the stimulus value signals in the real choice condition. The findings suggest that the difference between real and hypothetical choice is primarily attributable to variations in the value computations of the medial orbitofrontal cortex and the ventral striatum, and not attributable to the use of different valuation systems, or to the computation of stronger stimulus value signals in the hypothetical condition. PMID:21228156

  13. Neutrino Detectors: Challenges and Opportunities

    SciTech Connect

    Soler, F. J. P.

    2011-10-06

    This paper covers possible detector options suitable at future neutrino facilities, such as Neutrino Factories, Super Beams and Beta Beams. The Magnetised Iron Neutrino Detector (MIND), which is the baseline detector at a Neutrino Factory, will be described and a new analysis which improves the efficiency of this detector at low energies will be shown. Other detectors covered include the Totally Active Scintillating Detectors (TASD), particularly relevant for a low energy Neutrino Factory, emulsion detectors for tau detection, liquid argon detectors and megaton scale water Cherenkov detectors. Finally the requirements of near detectors for long-baseline neutrino experiments will be demonstrated.

  14. IAEA activities in the area of partitioning and transmutation

    NASA Astrophysics Data System (ADS)

    Stanculescu, Alexander

    2006-06-01

    Four major challenges are facing the long-term development of nuclear energy: improvement of the economic competitiveness, meeting increasingly stringent safety requirements, adhering to the criteria of sustainable development, and public acceptance. Meeting the sustainability criteria is the driving force behind the topic of this paper. In this context, sustainability has two aspects: natural resources and waste management. IAEA's activities in the area of Partitioning and Transmutation (P&T) are mostly in response to the latter. While not involving the large quantities of gaseous products and toxic solid wastes associated with fossil fuels, radioactive waste disposal is today's dominant public acceptance issue. In fact, small waste quantities permit a rigorous confinement strategy, and mined geological disposal is the strategy followed by some countries. Nevertheless, political opposition arguing that this does not yet constitute a safe disposal technology has largely stalled these efforts. One of the primary reasons cited is the long life of many of the radioisotopes generated from fission. This concern has led to increased R&D efforts to develop a technology aimed at reducing the amount and radio-toxicity of long-lived radioactive waste through transmutation in fission reactors or sub-critical systems. In the frame of the Project on Technology Advances in Fast Reactors and Accelerator-Driven Systems (ADS), the IAEA initiated a number of activities on utilization of plutonium and transmutation of long-lived radioactive waste, ADS, and deuterium-tritium plasma-driven sub-critical systems. The paper presents past accomplishments, current status and planned activities of this IAEA project.

  15. Tin Can Radiation Detector.

    ERIC Educational Resources Information Center

    Crull, John L.

    1986-01-01

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

  16. Characterisation activities of new NIR to VLWIR detectors from Selex ES Ltd at the UK ATC

    NASA Astrophysics Data System (ADS)

    Bezawada, Naidu; Atkinson, David; Shorrocks, Nick; Hipwood, Les; Weller, Harald; Bryson, Ian; Jackson, Malcolm; Davis, Ray P.; Barnes, Keith; Baker, Ian

    2014-07-01

    The UKATC has undertaken to test and evaluate new infrared detectors being developed at Selex ES Ltd, Southampton in the UK for astronomy and space applications. Current programmes include: the evaluation of large format (1280×1024), near-infrared detectors for astronomy, the characterisation of shortwave infrared detectors (up to 2.5μm) for satellite-based earth observation, long wavelength (8 to 11μm) and very long wavelength (10 to 14.5μm cut-off) devices for cosmos applications. Future programmes include the evaluation of large format, avalanche photodiode arrays for photon-level sensing and high speed applications. Custom test facilities are being setup in order to drive and characterise the detectors at the ATC under conditions representative of the applications. In this paper the test facilities will be described along with the associated challenges to evaluate the performance of these detectors. The paper also includes an overview of the Selex ES detectors, including the ROICs and the MOVPE HgCdTe arrays, and will present the latest results from the characterisation program.

  17. Segmented Ge detector rejection of internal beta activity produced by neutron irradiation

    NASA Technical Reports Server (NTRS)

    Varnell, L. S.; Callas, J. L.; Mahoney, W. A.; Pehl, R. H.; Landis, D. A.

    1991-01-01

    Future Ge spectrometers flown in space to observe cosmic gamma-ray sources will incorporate segmented detectors to reduce the background from radioactivity produced by energetic particle reactions. To demonstrate the effectiveness of a segmented Ge detector in rejecting background events due to the beta decay of internal radioactivity, a laboratory experiment has been carried out in which radioactivity was produced in the detector by neutron irradiation. A Cf-252 source of neutrons was used to produce, by neutron capture on Ge-74 (36.5 percent of natural Ge) in the detector itself, Ge-75 (t sub 1/2 = 82.78 min), which decays by beta emission with a maximum electron kinetic energy of 1188 keV. By requiring that an ionizing event deposit energy in two or more of the five segments of the detector, each about 1-cm thick, the beta particles, which have a range of about 1-mm, are rejected, while most external gamma rays incident on the detector are counted. Analysis of this experiment indicates that over 85 percent of the beta events from the decay of Ge-75 are rejected, which is in good agreement with Monte Carlo calculations.

  18. The First Tests of a Large-Area Light Detector Equipped with Metallic Magnetic Calorimeters for Scintillating Bolometers for the LUMINEU Neutrinoless Double Beta Decay Search

    NASA Astrophysics Data System (ADS)

    Gray, D.; Enss, C.; Fleischmann, A.; Gastaldo, L.; Hassel, C.; Hengstler, D.; Kempf, S.; Loidl, M.; Navick, X. F.; Rodrigues, M.

    2016-02-01

    Future rare-event searches using scintillating crystals need very low background levels for high sensitivity; however, unresolved pile-up can limit this. We present the design and fabrication of large-area photon detectors based on metallic magnetic calorimeters (MMCs), optimized for fast rise times to resolve close pile-up. The first prototypes have been characterized using Fe-55 X-rays and ZnMoO4 crystal scintillation light. A fast intrinsic rise time of 25-30 \\upmu s has been measured and has been compared to the 250 \\upmu s scintillation light pulse rise time constant. The difference indicates that the scintillation process limits the light pulse rise time. The fast rise time allows for a reduction of background due to close pile-up events as well as the study of the inherent crystal scintillation process. MMC-based photon detectors are shown to be a promising tool for scintillating crystal based rare event searches.

  19. The First Tests of a Large-Area Light Detector Equipped with Metallic Magnetic Calorimeters for Scintillating Bolometers for the LUMINEU Neutrinoless Double Beta Decay Search

    NASA Astrophysics Data System (ADS)

    Gray, D.; Enss, C.; Fleischmann, A.; Gastaldo, L.; Hassel, C.; Hengstler, D.; Kempf, S.; Loidl, M.; Navick, X. F.; Rodrigues, M.

    2016-08-01

    Future rare-event searches using scintillating crystals need very low background levels for high sensitivity; however, unresolved pile-up can limit this. We present the design and fabrication of large-area photon detectors based on metallic magnetic calorimeters (MMCs), optimized for fast rise times to resolve close pile-up. The first prototypes have been characterized using Fe-55 X-rays and ZnMoO4 crystal scintillation light. A fast intrinsic rise time of 25-30 \\upmu s has been measured and has been compared to the 250 \\upmu s scintillation light pulse rise time constant. The difference indicates that the scintillation process limits the light pulse rise time. The fast rise time allows for a reduction of background due to close pile-up events as well as the study of the inherent crystal scintillation process. MMC-based photon detectors are shown to be a promising tool for scintillating crystal based rare event searches.

  20. Observations of a gamma-ray burst and other sources with a large-area, balloon-borne detector

    NASA Technical Reports Server (NTRS)

    Wilson, R. B.; Fishman, G. J.; Meegan, C. A.

    1982-01-01

    Observations of a weak cosmic gamma ray burst of integrated intensity 2 x 10 to the -6th erg/sq cm, two solar flare events, and pulsed emission profiles of A0535+26 and NP0532 are reported for several energy intervals in the energy range from 45 to 520 keV. The measurements were made with a NaI(Tl) detector array flown on a balloon to 4 g/sq cm residual atmosphere from Palestine, Texas, on October 6-8, 1980, for 28 hours. The detector is a prototype of the Burst and Transient Source Experiment (BATSE) to be flown on the Gamma-Ray Observatory (GRO).

  1. DND-CAT;s new triple area detector system for simultaneous data collection at multiple length scales

    SciTech Connect

    Weigand, Steven J.; Keane, Denis T.

    2011-11-17

    The DuPont-Northwestern-Dow Collaborative Access Team (DND-CAT) built and currently manages sector 5 at the Advanced Photon Source (APS), Argonne National Laboratory. One of the principal techniques supported by DND-CAT is Small and Wide-Angle X-ray Scattering (SAXS/WAXS), with an emphasis on simultaneous data collection over a wide azimuthal and reciprocal space range using a custom SAXS/WAXS detector system. A new triple detector system is now in development, and we describe the key parameters and characteristics of the new instrument, which will be faster, more flexible, more robust, and will improve q-space resolution in a critical reciprocal space regime between the traditional WAXS and SAXS ranges.

  2. ECVAM's ongoing activities in the area of acute oral toxicity.

    PubMed

    Kinsner-Ovaskainen, Agnieszka; Bulgheroni, Anna; Hartung, Thomas; Prieto, Pilar

    2009-12-01

    The 7th Amendment of the Cosmetics Directive (2003/15/EC) set up timelines for banning animal testing and marketing of cosmetic products and their ingredients tested on animals. For most of the human health effects, including acute toxicity, the deadline for these bans was in March 2009. Moreover, the new Regulation EC 1907/2006 on Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) provided a strong impetus towards the application of alternative approaches to reduce the number of animals used for toxicological testing. Therefore, the European Centre for the Validation of Alternative Methods (ECVAM) is currently putting considerable effort into developing and validating alternative methods in the field of acute toxicity. The main activities in this area include: (1) the Integrated Project ACuteTox, funded by the European Commission's 6th Framework Programme in 2005 with the aim to develop and pre-validate a testing strategy to fully replace acute oral toxicity testing in vivo; (2) a follow-up validation study to assess the predictive capacity of the validated BALB/3T3 Neutral Red Uptake cytotoxicity assay to discriminate between toxic/hazardous (LD(50)<2,000 mg/kg) substances and substances not classified for acute toxicity (LD(50)>2,000 mg/kg); (3) an approach to identify compounds with LD(50)>2,000 mg/kg using information from 28-days repeated dose toxicity studies. PMID:19591916

  3. Flexible and mechanical strain resistant large area SERS active substrates

    NASA Astrophysics Data System (ADS)

    Singh, J. P.; Chu, Hsiaoyun; Abell, Justin; Tripp, Ralph A.; Zhao, Yiping

    2012-05-01

    We report a cost effective and facile way to synthesize flexible, uniform, and large area surface enhanced Raman scattering (SERS) substrates using an oblique angle deposition (OAD) technique. The flexible SERS substrates consist of 1 μm long, tilted silver nanocolumnar films deposited on flexible polydimethylsiloxane (PDMS) and polyethylene terephthalate (PET) sheets using OAD. The SERS enhancement activity of these flexible substrates was determined using 10-5 M trans-1,2-bis(4-pyridyl) ethylene (BPE) Raman probe molecules. The in situ SERS measurements on these flexible substrates under mechanical (tensile/bending) strain conditions were performed. Our results show that flexible SERS substrates can withstand a tensile strain (ε) value as high as 30% without losing SERS performance, whereas the similar bending strain decreases the SERS performance by about 13%. A cyclic tensile loading test on flexible PDMS SERS substrates at a pre-specified tensile strain (ε) value of 10% shows that the SERS intensity remains almost constant for more than 100 cycles. These disposable and flexible SERS substrates can be integrated with biological substances and offer a novel and practical method to facilitate biosensing applications.

  4. Measurements of ambient volatile organic carbons in rural, urban and areas with oil and gas activity in North Dakota

    NASA Astrophysics Data System (ADS)

    Hecobian, A.; Prenni, A. J.; Day, D.; Zhou, Y.; Sive, B. C.; Schichtel, B. A.; Collett, J. L., Jr.

    2014-12-01

    Recent increases in oil and gas extraction activities and well counts in North Dakota have raised questions on the ambient impact of the emissions from these processes. A Chevy Tahoe SUV was equipped with a PICARRO G2203 analyzer to measure methane and acetylene, a PICARRO A0941 mobile kit to measure GPS coordinates, an AethLabs micro-aethalometer to measure black carbon concentrations and a Radiance Research nephelometer to measure light scattering coefficient values. The SUV was used as a mobile platform to drive through different locations in North Dakota and measure the compounds noted above and also collect ambient air samples. The methane and acetylene concentrations were used to identify areas of interest, where evacuated stainless steel canisters were used to collect air samples and then transported to the laboratory where a three gas chromatograph system equipped with two flame ionization detectors (FID), two electron capture detectors (ECD), and a mass spectrometer (MS) was used to measure various VOC concentrations. The results from these measurements will be discussed here with an emphasis on the differences between rural and urban areas and locations with high instances oil and gas activities.

  5. TFT-Based Active Pixel Sensors for Large Area Thermal Neutron Detection

    NASA Astrophysics Data System (ADS)

    Kunnen, George

    Due to diminishing availability of 3He, which is the critical component of neutron detecting proportional counters, large area flexible arrays are being considered as a potential replacement for neutron detection. A large area flexible array, utilizing semiconductors for both charged particle detection and pixel readout, ensures a large detection surface area in a light weight rugged form. Such a neutron detector could be suitable for deployment at ports of entry. The specific approach used in this research, uses a neutron converter layer which captures incident thermal neutrons, and then emits ionizing charged particles. These ionizing particles cause electron-hole pair generation within a single pixel's integrated sensing diode. The resulting charge is then amplified via a low-noise amplifier. This document begins by discussing the current state of the art in neutron detection and the associated challenges. Then, for the purpose of resolving some of these issues, recent design and modeling efforts towards developing an improved neutron detection system are described. Also presented is a low-noise active pixel sensor (APS) design capable of being implemented in low temperature indium gallium zinc oxide (InGaZnO) or amorphous silicon (a-Si:H) thin film transistor process compatible with plastic substrates. The low gain and limited scalability of this design are improved upon by implementing a new multi-stage self-resetting APS. For each APS design, successful radiation measurements are also presented using PiN diodes for charged particle detection. Next, detection array readout methodologies are modeled and analyzed, and use of a matched filter readout circuit is described as well. Finally, this document discusses detection diode integration with the designed TFT-based APSs.

  6. A High-Speed, Event-Driven, Active Pixel Sensor Readout for Photon-Counting Microchannel Plate Detectors

    NASA Technical Reports Server (NTRS)

    Kimble, Randy A.; Pain, Bedabrata; Norton, Timothy J.; Haas, J. Patrick; Oegerle, William R. (Technical Monitor)

    2002-01-01

    Silicon array readouts for microchannel plate intensifiers offer several attractive features. In this class of detector, the electron cloud output of the MCP intensifier is converted to visible light by a phosphor; that light is then fiber-optically coupled to the silicon array. In photon-counting mode, the resulting light splashes on the silicon array are recognized and centroided to fractional pixel accuracy by off-chip electronics. This process can result in very high (MCP-limited) spatial resolution while operating at a modest MCP gain (desirable for dynamic range and long term stability). The principal limitation of intensified CCD systems of this type is their severely limited local dynamic range, as accurate photon counting is achieved only if there are not overlapping event splashes within the frame time of the device. This problem can be ameliorated somewhat by processing events only in pre-selected windows of interest of by using an addressable charge injection device (CID) for the readout array. We are currently pursuing the development of an intriguing alternative readout concept based on using an event-driven CMOS Active Pixel Sensor. APS technology permits the incorporation of discriminator circuitry within each pixel. When coupled with suitable CMOS logic outside the array area, the discriminator circuitry can be used to trigger the readout of small sub-array windows only when and where an event splash has been detected, completely eliminating the local dynamic range problem, while achieving a high global count rate capability and maintaining high spatial resolution. We elaborate on this concept and present our progress toward implementing an event-driven APS readout.

  7. A High-Speed, Event-Driven, Active Pixel Sensor Readout for Photon-Counting Microchannel Plate Detectors

    NASA Technical Reports Server (NTRS)

    Kimble, Randy A.; Pain, B.; Norton, T. J.; Haas, P.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    Silicon array readouts for microchannel plate intensifiers offer several attractive features. In this class of detector, the electron cloud output of the MCP intensifier is converted to visible light by a phosphor; that light is then fiber-optically coupled to the silicon array. In photon-counting mode, the resulting light splashes on the silicon array are recognized and centroided to fractional pixel accuracy by off-chip electronics. This process can result in very high (MCP-limited) spatial resolution for the readout while operating at a modest MCP gain (desirable for dynamic range and long term stability). The principal limitation of intensified CCD systems of this type is their severely limited local dynamic range, as accurate photon counting is achieved only if there are not overlapping event splashes within the frame time of the device. This problem can be ameliorated somewhat by processing events only in pre-selected windows of interest or by using an addressable charge injection device (CID) for the readout array. We are currently pursuing the development of an intriguing alternative readout concept based on using an event-driven CMOS Active Pixel Sensor. APS technology permits the incorporation of discriminator circuitry within each pixel. When coupled with suitable CMOS logic outside the array area, the discriminator circuitry can be used to trigger the readout of small sub-array windows only when and where an event splash has been detected, completely eliminating the local dynamic range problem, while achieving a high global count rate capability and maintaining high spatial resolution. We elaborate on this concept and present our progress toward implementing an event-driven APS readout.

  8. 50 CFR 218.180 - Specified activity and specified geographical area and effective dates.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Mission Activities in the Naval Surface Warfare Center Panama City Division § 218.180 Specified activity... operations) W-151 (includes Panama City Operating Area), W-155 (includes Pensacola Operating Area), and...

  9. 33 CFR 334.763 - Naval Support Activity Panama City; Gulf of Mexico; restricted area.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Naval Support Activity Panama City; Gulf of Mexico; restricted area. 334.763 Section 334.763 Navigation and Navigable Waters CORPS OF....763 Naval Support Activity Panama City; Gulf of Mexico; restricted area. (a) The area. The area...

  10. Invited Article: A test-facility for large-area microchannel plate detector assemblies using a pulsed sub-picosecond laser

    NASA Astrophysics Data System (ADS)

    Adams, Bernhard; Chollet, Matthieu; Elagin, Andrey; Oberla, Eric; Vostrikov, Alexander; Wetstein, Matthew; Obaid, Razib; Webster, Preston

    2013-06-01

    The Large Area Picosecond Photodetector Collaboration is developing large-area fast photodetectors with time resolution ≲10 ps and space resolution ≲1 mm based on atomic layer deposition-coated glass Micro-Channel Plates (MCPs). We have assembled a facility at Argonne National Laboratory for characterizing the performance of a wide variety of microchannel plate configurations and anode structures in configurations approaching complete detector systems. The facility consists of a pulsed Ti:Sapphire laser with a pulse duration ≈100 fs, an optical system allowing the laser to be scanned in two dimensions, and a computer-controlled data-acquisition system capable of reading out 60 channels of anode signals with a sampling rate of over 10 GS/s. The laser can scan on the surface of a sealed large-area photodetector, or can be introduced into a large vacuum chamber for tests on bare 8 in.-square MCP plates or into a smaller chamber for tests on 33-mm circular substrates. We present the experimental setup, detector calibration, data acquisition, analysis tools, and typical results demonstrating the performance of the test facility.

  11. Development of large area diamond detectors for time-of-flight measurements of relativistic heavy ions for the super-FRS

    NASA Astrophysics Data System (ADS)

    Schirru, F.; Nociforo, C.; Kiš, M.; Ciobanu, M.; Frühauf, J.; Kratz, A.; Kurz, N.; Szczepanczyk, B.; Träger, M.; Visinka, R.

    2016-06-01

    Time-of-flight (ToF) performances of large area diamond detectors based on polycrystalline samples of dimensions 20 mm  ×  20 mm and thickness of 0.3 mm are presented. The devices that feature segmented Cr/Au electrodes in a sandwich configuration were irradiated with a heavy ions 197Au beam of 1 GeV u‑1 showing, when mounted with a separation distance of 2 cm, a ToF resolution \\barσ of 37.5 ps averaged on 16 strip pairs. When ToF measurements were performed over a particle path of 30 m, a resolution σ of 45 ps was achieved. The detectors were mounted on high-vacuum compatible printed circuit boards (PCBs) with integrated processing electronics. This is the first time that ToF measurements have been performed using integrated electronics with such a large separation distance between the diamond detectors.

  12. Six-circle diffractometer with atmosphere- and temperature-controlled sample stage and area and line detectors for use in the G2 experimental station at CHESS

    SciTech Connect

    Nowak, D. E.; Blasini, D. R.; Vodnick, A. M.; Blank, B.; Tate, M. W.; Deyhim, A.; Smilgies, D.-M.; Abruna, H.; Gruner, S. M.; Baker, S. P.

    2006-11-15

    A new diffractometer system was designed and built for the G2 experimental station at the Cornell High Energy Synchrotron Source (CHESS). A six-circle {kappa} goniometer, which provides better access to reciprocal space compared to Eulerian cradles, was chosen primarily to perform large angle Bragg diffraction on samples with preferred crystallographic orientations, and can access both horizontal and vertical diffraction planes. A new atmosphere- and temperature-controlled sample stage was designed for thin film thermomechanical experiments. The stage can be operated in ultrahigh vacuum and uses a Be dome x-ray window to provide access to all scattering vectors above a sample's horizon. A novel design minimizes sample displacements during thermal cycling to less than 160 {mu}m over 900 deg. C and the stage is motorized for easy height adjustments, which can be used to compensate for displacements from thermal expansion. A new area detector was built and a new line detector was purchased. Both detectors cover a large region in reciprocal space, providing the ability to measure time-resolved phenomena. A detailed description of the design and technical characteristics is given. Some capabilities of the diffractometer system are illustrated by a strain analysis on a thin metal film and characterization of organic thin films with grazing incidence diffraction. The G2 experimental station, as part of CHESS, is a national user facility and is available to external users by application.

  13. 33 CFR 334.763 - Naval Support Activity Panama City; Gulf of Mexico; restricted area.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Naval Support Activity Panama....763 Naval Support Activity Panama City; Gulf of Mexico; restricted area. (a) The area. The area is... enforced by the Commanding Officer, Naval Support Activity, Panama City Florida, and such agencies as...

  14. Thick activation detectors for neutron spectrometry using different unfolding methods: sensitivity analysis and dose calculation.

    PubMed

    Medkour Ishak-Boushaki, Ghania; Boukeffoussa, Khelifa; Idiri, Zahir; Allab, Malika

    2012-03-01

    This paper discusses the use of threshold detectors of extended sizes for low intensity neutron fields' characterization. The detectors were tested by the measurement of the neutron spectrum of an (241)Am-Be source. Integral quantities characterizing the neutron field, required for radiological protection, have been derived by unfolding the measured data. A good agreement is achieved between the obtained results and those deduced using Bonner spheres. In addition, a sensitivity analysis of the results to the deconvolution procedure is given. PMID:22119561

  15. Technical Basis for the Use of Alarming Personal Criticality Detectors to Augment Permanent Nuclear Incident Monitor (NIM) Systems in Areas Not Normally Occupied

    SciTech Connect

    Yates, K.R.

    2003-05-26

    The technical basis for the use of alarming personal criticality detectors (APCDs) to augment permanent Nuclear Incident Monitor (NIM) Systems in areas not normally occupied is evaluated. All applicable DOE O 420.1A and ANSI/ANS-8.3-1997 criticality alarm system requirements and recommendations are evaluated for applicability to APCDs. Based on this evaluation, design criteria and administrative requirements are presented for APCDs. Siemens EPD/Mk-2 and EPD-N devices are shown to meet the design criteria. A definition of not normally occupied is also presented.

  16. Neural activation in arousal and reward areas of the brain in day-active and night-active grass rats.

    PubMed

    Castillo-Ruiz, A; Nixon, J P; Smale, L; Nunez, A A

    2010-01-20

    In the diurnal unstriped Nile grass rat (Arvicanthis niloticus) access to a running wheel can trigger a shift in active phase preference, with some individuals becoming night-active (NA), while others continue to be day-active (DA). To investigate the contributions of different neural systems to the support of this shift in locomotor activity, we investigated the association between chronotype and Fos expression during the day and night in three major nuclei in the basal forebrain (BF) cholinergic (ACh) arousal system - medial septum (MS), vertical and horizontal diagonal band of Broca (VDB and HDB respectively) -, and whether neural activation in these areas was related to neural activity in the orexinergic system. We also measured Fos expression in dopaminergic and non-dopaminergic cells of two components of the reward system that also participate in arousal - the ventral tegmental area (VTA) and supramammillary nucleus (SUM). NAs and DAs were compared to animals with no wheels. NAs had elevated Fos expression at night in ACh cells, but only in the HDB. In the non-cholinergic cells of the BF of NAs, enhanced nocturnal Fos expression was almost universally seen, but only associated with activation of the orexinergic system for the MS/VDB region. For some of the areas and cell types of the BF, the patterns of Fos expression of DAs appeared similar to those of NAs, but were never associated with activation of the orexinergic system. Also common to DAs and NAs was a general increase in Fos expression in non-dopaminergic cells of the SUM and anterior VTA. Thus, in this diurnal species, voluntary exercise and a shift to a nocturnal chronotype changes neural activity in arousal and reward areas of the brain known to regulate a broad range of neural functions and behaviors, which may be also affected in human shift workers. PMID:19837140

  17. 33 CFR 334.763 - Naval Support Activity Panama City; Gulf of Mexico; restricted area.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... City; Gulf of Mexico; restricted area. 334.763 Section 334.763 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.763 Naval Support Activity Panama City; Gulf of Mexico; restricted area. (a) The area. The area...

  18. 33 CFR 334.763 - Naval Support Activity Panama City; Gulf of Mexico; restricted area.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... City; Gulf of Mexico; restricted area. 334.763 Section 334.763 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.763 Naval Support Activity Panama City; Gulf of Mexico; restricted area. (a) The area. The area...

  19. 33 CFR 334.763 - Naval Support Activity Panama City; Gulf of Mexico; restricted area.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... City; Gulf of Mexico; restricted area. 334.763 Section 334.763 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.763 Naval Support Activity Panama City; Gulf of Mexico; restricted area. (a) The area. The area...

  20. Detector simulation needs for detector designers

    SciTech Connect

    Hanson, G.G.

    1987-11-01

    Computer simulation of the components of SSC detectors and of the complete detectors will be very important for the designs of the detectors. The ratio of events from interesting physics to events from background processes is very low, so detailed understanding of detector response to the backgrounds is needed. Any large detector for the SSC will be very complex and expensive and every effort must be made to design detectors which will have excellent performance and will not have to undergo major rebuilding. Some areas in which computer simulation is particularly needed are pattern recognition in tracking detectors and development of shower simulation code which can be trusted as an aid in the design and optimization of calorimeters, including their electron identification performance. Existing codes require too much computer time to be practical and need to be compared with test beam data at energies of several hundred GeV. Computer simulation of the processing of the data, including electronics response to the signals from the detector components, processing of the data by microprocessors on the detector, the trigger, and data acquisition will be required. In this report we discuss the detector simulation needs for detector designers.

  1. 50 CFR 218.120 - Specified activity and geographical area.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... the following mid-frequency active sonar (MFAS) sources, high-frequency active sonar (HFAS) sources...-mounted active sonar)—up to 2,890 hours over the course of 5 years (an average of 578 hours per year); (ii) AN/SQS-56 (hull-mounted active sonar)—up to 260 hours over the course of 5 years (an average of...

  2. 50 CFR 218.120 - Specified activity and geographical area.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... the following mid-frequency active sonar (MFAS) sources, high-frequency active sonar (HFAS) sources...-mounted active sonar)—up to 2,890 hours over the course of 5 years (an average of 578 hours per year); (ii) AN/SQS-56 (hull-mounted active sonar)—up to 260 hours over the course of 5 years (an average of...

  3. 50 CFR 218.120 - Specified activity and geographical area.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... the following mid-frequency active sonar (MFAS) sources, high-frequency active sonar (HFAS) sources...-mounted active sonar)—up to 2,890 hours over the course of 5 years (an average of 578 hours per year); (ii) AN/SQS-56 (hull-mounted active sonar)—up to 260 hours over the course of 5 years (an average of...

  4. 50 CFR 218.120 - Specified activity and geographical area.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... the following mid-frequency active sonar (MFAS) sources, high-frequency active sonar (HFAS) sources...-mounted active sonar)—up to 2,890 hours over the course of 5 years (an average of 578 hours per year); (ii) AN/SQS-56 (hull-mounted active sonar)—up to 260 hours over the course of 5 years (an average of...

  5. Environmental Print Activities for Teaching Mathematics and Content Areas.

    ERIC Educational Resources Information Center

    Rule, Audrey C., Ed.; McIntyre, Sandra, Ed.; Ranous, Meg, Ed.

    Twenty-three mathematics activities that use environmental print materials are presented, along with two activities that focus on music education, one that highlights history concepts, and five science activities. The environmental print materials are words and images cut from food or other product packaging and mounted on mat board cards.…

  6. Universal EUV in-band intensity detector

    DOEpatents

    Berger, Kurt W.

    2004-08-24

    Extreme ultraviolet light is detected using a universal in-band detector for detecting extreme ultraviolet radiation that includes: (a) an EUV sensitive photodiode having a diode active area that generates a current responsive to EUV radiation; (b) one or more mirrors that reflects EUV radiation having a defined wavelength(s) to the diode active area; and (c) a mask defining a pinhole that is positioned above the diode active area, wherein EUV radiation passing through the pinhole is restricted substantially to illuminating the diode active area.

  7. SCIENCE AND TECHNOLOGY ACTIVITIES FOR CHROMIUM IN THE 100 AREAS

    SciTech Connect

    PETERSEN SW

    2009-07-02

    {sm_bullet} Primary Objective: Protect the Columbia River - Focus is control and treatment of contamination at or near the shoreline, which is influenced by bank storage {sm_bullet} Secondary Objective: Reduce hexavalent chromium to <48 parts per billion (ppb) in aquifer (drinking water standard) - Large plumes with isolated areas of high chromium concentrations (> 40,000 ppb), - Unknown source location(s); probably originating in reactor operation areas

  8. Performance of the large-area detectors for the Burst and Transient Source Experiment (BATSE) on the Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Paciesas, W. S.; Pendleton, G. N.; Lestrade, J. P.; Fishman, G. J.; Meegan, C. A.; Wilson, R. B.; Parnell, T. A.; Austin, R. W.; Berry, F. A., Jr.; Horack, J. M.

    1989-01-01

    BATSE, one of four experiments on the Gamma Ray Observatory (GRO), is expected to provide the most sensitive observations of gamma-ray bursts yet obtained, as well as to provide long-term monitoring of hard X-ray and low-energy gamma-ray emission from bright pulsating sources, transients, and solar flares. Eight uncollimated modules, positioned at the corners of the spacecraft to provide an unobstructed view of the sky, detect sources by various techniques based on time variability. Use of detectors with anisotropic response allows location of gamma-ray bursts to be determined to an accuracy of about 1 deg using BATSE data alone. The completed BATSE underwent intensive testing and calibration prior to its delivery in October 1988.

  9. Note: Application of a pixel-array area detector to simultaneous single crystal x-ray diffraction and x-ray absorption spectroscopy measurements

    SciTech Connect

    Sun, Cheng-Jun Brewe, Dale L.; Heald, Steve M.; Zhang, Bangmin; Chen, Jing-Sheng; Chow, G. M.; Venkatesan, T.

    2014-04-15

    X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) are two main x-ray techniques in synchrotron radiation facilities. In this Note, we present an experimental setup capable of performing simultaneous XRD and XAS measurements by the application of a pixel-array area detector. For XRD, the momentum transfer in specular diffraction was measured by scanning the X-ray energy with fixed incoming and outgoing x-ray angles. By selecting a small fixed region of the detector to collect the XRD signal, the rest of the area was available for collecting the x-ray fluorescence for XAS measurements. The simultaneous measurement of XRD and X-ray absorption near edge structure for Pr{sub 0.67}Sr{sub 0.33}MnO{sub 3} film was demonstrated as a proof of principle for future time-resolved pump-probe measurements. A static sample makes it easy to maintain an accurate overlap of the X-ray spot and laser pump beam.

  10. Multi-segment detector

    NASA Technical Reports Server (NTRS)

    George, Peter K. (Inventor)

    1978-01-01

    A plurality of stretcher detector segments are connected in series whereby detector signals generated when a bubble passes thereby are added together. Each of the stretcher detector segments is disposed an identical propagation distance away from passive replicators wherein bubbles are replicated from a propagation path and applied, simultaneously, to the stretcher detector segments. The stretcher detector segments are arranged to include both dummy and active portions thereof which are arranged to permit the geometry of both the dummy and active portions of the segment to be substantially matched.

  11. Wide-area SWIR arrays and active illuminators

    NASA Astrophysics Data System (ADS)

    MacDougal, Michael; Hood, Andrew; Geske, Jon; Wang, Chad; Renner, Daniel; Follman, David; Heu, Paula

    2012-01-01

    We describe the factors that go into the component choices for a short wavelength (SWIR) imager, which include the SWIR sensor, the lens, and the illuminator. We have shown the factors for reducing dark current, and shown that we can achieve well below 1.5 nA/cm2 for 15 μm devices at 7°C. We have mated our InGaAs detector arrays to 640x512 readout integrated integrated circuits (ROICs) to make focal plane arrays (FPAs). In addition, we have fabricated high definition 1920x1080 FPAs for wide field of view imaging. The resulting FPAs are capable of imaging photon fluxes with wavelengths between 1 and 1.6 microns at low light levels. The dark current associated with these FPAs is extremely low, exhibiting a mean dark current density of 0.26 nA/cm2 at 0°C. FLIR has also developed a high definition, 1920x1080, 15 um pitch SWIR sensor. In addition, FLIR has developed laser arrays that provide flat illumination in scenes that are normally light-starved. The illuminators have 40% wall-plug efficiency and provide low-speckle illumination, provide artifact-free imagery versus conventional laser illuminators.

  12. Simulation of active-edge pixelated CdTe radiation detectors

    NASA Astrophysics Data System (ADS)

    Duarte, D. D.; Lipp, J. D.; Schneider, A.; Seller, P.; Veale, M. C.; Wilson, M. D.; Baker, M. A.; Sellin, P. J.

    2016-01-01

    The edge surfaces of single crystal CdTe play an important role in the electronic properties and performance of this material as an X-ray and γ-ray radiation detector. Edge effects have previously been reported to reduce the spectroscopic performance of the edge pixels in pixelated CdTe radiation detectors without guard bands. A novel Technology Computer Aided Design (TCAD) model based on experimental data has been developed to investigate these effects. The results presented in this paper show how localized low resistivity surfaces modify the internal electric field of CdTe creating potential wells. These result in a reduction of charge collection efficiency of the edge pixels, which compares well with experimental data.

  13. Acoustic detection of biosonar activity of deep diving odontocetes at Josephine Seamount High Seas Marine Protected Area.

    PubMed

    Giorli, Giacomo; Au, Whitlow W L; Ou, Hui; Jarvis, Susan; Morrissey, Ronald; Moretti, David

    2015-05-01

    The temporal occurrence of deep diving cetaceans in the Josephine Seamount High Seas Marine Protected Area (JSHSMPA), south-west Portugal, was monitored using a passive acoustic recorder. The recorder was deployed on 13 May 2010 at a depth of 814 m during the North Atlantic Treaty Organization Centre for Maritime Research and Experimentation cruise "Sirena10" and recovered on 6 June 2010. The recorder was programmed to record 40 s of data every 2 min. Acoustic data analysis, for the detection and classification of echolocation clicks, was performed using automatic detector/classification systems: M3R (Marine Mammal Monitoring on Navy Ranges), a custom matlab program, and an operator-supervised custom matlab program to assess the classification performance of the detector/classification systems. M3R CS-SVM algorithm contains templates to detect beaked whales, sperm whales, blackfish (pilot and false killer whales), and Risso's dolphins. The detections of each group of odontocetes was monitored as a function of time. Blackfish and Risso's dolphins were detected every day, while beaked whales and sperm whales were detected almost every day. The hourly distribution of detections reveals that blackfish and Risso's dolphins were more active at night, while beaked whales and sperm whales were more active during daylight hours. PMID:25994682

  14. INSA Scientific Activities in the Space Astronomy Area

    NASA Astrophysics Data System (ADS)

    Pérez Martínez, Ricardo; Sánchez Portal, Miguel

    Support to astronomy operations is an important and long-lived activity within INSA. Probably the best known (and traditional) INSA activities are those related with real-time spacecraft operations: ground station maintenance and operation (ground station engineers and operators); spacecraft and payload real-time operation (spacecraft and instruments controllers); computing infrastructure maintenance (operators, analysts), and general site services. In this paper, we’ll show a different perspective, probably not so well-known, presenting some INSA recent activities at the European Space Astronomy Centre (ESAC) and NASA Madrid Deep Space Communication Complex (MDSCC) directly related to scientific operations. Basic lines of activity involved include: operations support for science operations; system and software support for real time systems; technical administration and IT support; R&D activities, radioastronomy (at MDSCC and ESAC), and scientific research projects. This paper is structured as follows: first, INSA activities in two ESA cornerstone astrophysics missions, XMM-Newton and Herschel, will be outlined. Then, our activities related to scientific infrastructure services, represented by the Virtual Observatory (VO) framework and the Science Archives development facilities, are briefly shown. Radio astronomy activities will be described afterwards, and, finally, a few research topics in which INSA scientists are involved will also be described.

  15. Neutron Activation and Thermoluminescent Detector Responses to a Bare Pulse of the CEA Valduc SILENE Critical Assembly

    SciTech Connect

    Miller, Thomas Martin; Celik, Cihangir; McMahan, Kimberly L.; Lee, Yi-kang; Gagnier, Emmanuel; Authier, Nicolas; Piot, Jerome; Jacquet, Xavier; Rousseau, Guillaume; Reynolds, Kevin H.

    2015-09-01

    This benchmark experiment was conducted as a joint venture between the US Department of Energy (DOE) and the French Commissariat à l'Energie Atomique (CEA). Staff at the Oak Ridge National Laboratory (ORNL) in the US and the Centre de Valduc in France planned this experiment. The experiment was conducted on October 11, 2010 in the SILENE critical assembly facility at Valduc. Several other organizations contributed to this experiment and the subsequent evaluation, including CEA Saclay, Lawrence Livermore National Laboratory (LLNL), the Y-12 National Security Complex (NSC), Babcock International Group in the United Kingdom, and Los Alamos National Laboratory (LANL). The goal of this experiment was to measure neutron activation and thermoluminescent dosimeter (TLD) doses from a source similar to a fissile solution critical excursion. The resulting benchmark can be used for validation of computer codes and nuclear data libraries as required when performing analysis of criticality accident alarm systems (CAASs). A secondary goal of this experiment was to qualitatively test performance of two CAAS detectors similar to those currently and formerly in use in some US DOE facilities. The detectors tested were the CIDAS MkX and the Rocky Flats NCD-91. These detectors were being evaluated to determine whether they would alarm, so they were not expected to generate benchmark quality data.

  16. Radiation-hard Active Pixel Sensors for HL-LHC Detector Upgrades based on HV-CMOS Technology

    NASA Astrophysics Data System (ADS)

    Miucci, A.; Gonella, L.; Hemperek, T.; Hügging, F.; Krüger, H.; Obermann, T.; Wermes, N.; Garcia-Sciveres, M.; Backhaus, M.; Capeans, M.; Feigl, S.; Nessi, M.; Pernegger, H.; Ristic, B.; Gonzalez-Sevilla, S.; Ferrere, D.; Iacobucci, G.; La Rosa, A.; Muenstermann, D.; George, M.; Große-Knetter, J.; Quadt, A.; Rieger, J.; Weingarten, J.; Bates, R.; Blue, A.; Buttar, C.; Hynds, D.; Kreidl, C.; Peric, I.; Breugnon, P.; Pangaud, P.; Godiot-Basolo, S.; Fougeron, D.; Bompard, F.; Clemens, J. C.; Liu, J.; Barbero, M.; Rozanov, A.; HV-CMOS Collaboration

    2014-05-01

    Luminosity upgrades are discussed for the LHC (HL-LHC) which would make updates to the detectors necessary, requiring in particular new, even more radiation-hard and granular, sensors for the inner detector region. A proposal for the next generation of inner detectors is based on HV-CMOS: a new family of silicon sensors based on commercial high-voltage CMOS technology, which enables the fabrication of part of the pixel electronics inside the silicon substrate itself. The main advantages of this technology with respect to the standard silicon sensor technology are: low material budget, fast charge collection time, high radiation tolerance, low cost and operation at room temperature. A traditional readout chip is still needed to receive and organize the data from the active sensor and to handle high-level functionality such as trigger management. HV-CMOS has been designed to be compatible with both pixel and strip readout. In this paper an overview of HV2FEI4, a HV-CMOS prototype in 180 nm AMS technology, will be given. Preliminary results after neutron and X-ray irradiation are shown.

  17. Diffraction measurements with a boron-based GEM neutron detector

    NASA Astrophysics Data System (ADS)

    Croci, Gabriele; Albani, Giorgia; Cazzaniga, Carlo; Perelli Cippo, Enrico; Schooneveld, Erik; Claps, Gerardo; Cremona, Anna; Grosso, Giovanni; Muraro, Andrea; Murtas, Fabrizio; Rebai, Marica; Scherillo, Antonella; Tardocchi, Marco; Gorini, Giuseppe

    2014-07-01

    The research of reliable substitutes of 3He detectors is an important task for the affordability of new neutron scattering instrumentation for future spallation sources like the European Spallation Source. GEM (Gas Electron Multiplier)-based detectors represent a valid alternative since they can combine high-rate capability, coverage of up to 1\\ \\text{m}^{2} area and good intrinsic spatial resolution (for this detector class it can be better than 0.5 mm). The first neutron diffraction measurements performed using a borated GEM detector are reported. The detector has an active area of 10 \\times 5\\ \\text{cm}^{2} and is equipped with a borated cathode. The GEM detector was read out using the standard ISIS Data Acquisition System. The comparison with measurements performed with standard 3He detectors shows that the broadening of the peaks measured on the diffractogram obtained with the GEM is 20-30% wider than the one obtained by 3He tubes but the active area of the GEM is twice that of 3He tubes. The GEM resolution is improved if half of its active area is considered. The signal-to-background ratio of the GEM is about 1.5 to 2 times lower than that of 3He. This measurement proves that GEM detectors can be used for neutron diffraction measurements and paves the way for their use at future neutron spallation sources.

  18. 36 CFR 294.25 - Mineral activities in Idaho Roadless Areas.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 2 2013-07-01 2013-07-01 false Mineral activities in Idaho... AGRICULTURE SPECIAL AREAS Idaho Roadless Area Management § 294.25 Mineral activities in Idaho Roadless Areas. (a) Nothing in this subpart shall be construed as restricting mineral leases, contracts, permits,...

  19. 36 CFR 294.25 - Mineral activities in Idaho Roadless Areas.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 2 2011-07-01 2011-07-01 false Mineral activities in Idaho... AGRICULTURE SPECIAL AREAS Idaho Roadless Area Management § 294.25 Mineral activities in Idaho Roadless Areas. (a) Nothing in this subpart shall be construed as restricting mineral leases, contracts, permits,...

  20. 36 CFR 294.25 - Mineral activities in Idaho Roadless Areas.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 2 2014-07-01 2014-07-01 false Mineral activities in Idaho... AGRICULTURE SPECIAL AREAS Idaho Roadless Area Management § 294.25 Mineral activities in Idaho Roadless Areas. (a) Nothing in this subpart shall be construed as restricting mineral leases, contracts, permits,...

  1. 36 CFR 294.25 - Mineral activities in Idaho Roadless Areas.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 2 2010-07-01 2010-07-01 false Mineral activities in Idaho... AGRICULTURE SPECIAL AREAS Idaho Roadless Area Management § 294.25 Mineral activities in Idaho Roadless Areas. (a) Nothing in this subpart shall be construed as restricting mineral leases, contracts, permits,...

  2. 36 CFR 294.25 - Mineral activities in Idaho Roadless Areas.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 2 2012-07-01 2012-07-01 false Mineral activities in Idaho... AGRICULTURE SPECIAL AREAS Idaho Roadless Area Management § 294.25 Mineral activities in Idaho Roadless Areas. (a) Nothing in this subpart shall be construed as restricting mineral leases, contracts, permits,...

  3. Bureau of Indian Affairs, Juneau Area Activities Report, 1975-76.

    ERIC Educational Resources Information Center

    Fisher, Joan E.

    Reflecting the changing role of the Bureau of Indian Affairs (BIA), this 1975-76 annual report on the BIA's Juneau Area Office and its activities focuses upon the BIA resources, services, and technical assistance afforded Alaska Natives in the Juneau area. Highlights of Juneau Area Office Activities are presented in conjunction with the office's…

  4. Intravascular imaging with a storage phosphor detector

    NASA Astrophysics Data System (ADS)

    Shikhaliev, Polad M.; Petrek, Peter; Matthews, Kenneth L., II; Fritz, Shannon G.; Bujenovic, L. Steven; Xu, Tong

    2010-05-01

    The aim of this study is to develop and test an intravascular positron imaging system based on a storage phosphor detector for imaging and detecting vulnerable plaques of human coronary arteries. The radiotracer F18-FDG accumulates in vulnerable plaques with inflammation of the overlying cap. The vulnerable plaques can, therefore, be imaged by recording positrons emitted from F18-FDG with a detector inserted into the artery. A prototype intravascular detector was constructed based on storage phosphor. The detector uses a flexible storage phosphor tube with 55 mm length, 2 mm diameter and 0.28 mm wall thickness. The intravascular detector is guided into the vessel using x-ray fluoroscopy and the accumulated x-ray signal must be erased prior to positron imaging. For this purpose, a light diffuser, 0.9 mm in diameter and 55 mm in length, was inserted into the detector tube. The light diffuser was connected to a laser source through a 2 m long optical fiber. The diffuser redirected the 0.38 W laser light to the inner surface of the phosphor detector to erase it. A heart phantom with 300 cm3 volume and three coronary arteries with 3.2 mm diameter and with several plaques was constructed. FDG solution with 0.5 µCi cm-3 activity concentration was filled in the heart and coronary arteries. The detector was inserted in a coronary artery and the signal from the plaques and surrounding background activity was recorded for 2 min. Then the phosphor detector was extracted and read out using a storage phosphor reader. The light diffuser erased the signal resulting from fluoroscopic exposure to level below that encountered during positron imaging. Vulnerable plaques with area activities higher than 1.2 nCi mm-2 were visualized by the detector. This activity is a factor of 10-20 lower than that expected in human vulnerable plaques. The detector was able to image the internal surface of the coronary vessels with 50 mm length and 360° circumference. Spatial resolution was 0

  5. Estimation of Performance of an Active Well Coincidence Counter Equipped with Boron-Coated Straw Neutron Detectors - 13401

    SciTech Connect

    Young, B.M.; Lacy, J.L.; Athanasiades, A.

    2013-07-01

    He-3, a very rare isotope of natural helium gas, has ideal properties for the detection of thermal neutrons. As such it has become the standard material for neutron detectors and sees ubiquitous use within many radiometric applications that require neutron sensitivity. Until recently, there has been a fairly abundant supply of He-3. However, with the reduction in nuclear weapons, production of tritium ceased decades ago and the stockpile has largely decayed away, reducing the available He-3 supply to a small fraction of that needed for neutron detection. A suitable and rapidly-deployable replacement technology for neutron detectors must be found. Many potential replacement technologies are under active investigation and development. One broad class of technologies utilizes B-10 as a neutron capture medium in coatings on the internal surfaces of proportional detectors. A particular implementation of this sort of technology is the boron-coated 'straw' (BCS) detectors under development by Proportional Technologies, Inc. (PTi). This technology employs a coating of B-10 enriched boron carbide (B{sub 4}C) on the inside of narrow tubes, roughly 4 mm in diameter. A neutron counter (e.g. a slab, a well counter, or a large assay counter designed to accommodate 200 liter drums) could be constructed by distributing these narrow tubes throughout the polyethylene body of the counter. One type of neutron counter that is of particular importance to safeguards applications is the Active Well Coincidence Counter (AWCC), which is a Los Alamos design that traditionally employs 42 He-3 detectors. This is a very flexible design which can accurately assay small samples of uranium- and plutonium-bearing materials. Utilizing the MCNPX code and benchmarking against measurements where possible, the standard AWCC has been redesigned to utilize the BCS technology. Particular aspects of the counter performance include the single-neutron ('singles') detection efficiency and the time constant for

  6. Fabrication of a thin silicon detector with excellent thickness uniformity

    NASA Astrophysics Data System (ADS)

    Valtonen, E.; Eronen, T.; Nenonen, S.; Andersson, H.; Miikkulainen, K.; Eränen, S.; Ronkainen, H.; Mäkinen, J.; Husu, H.; Lassila, A.; Punkkinen, R.; Hirvonen, M.

    2016-02-01

    We have fabricated and tested a thin silicon detector with the specific goal of having a very good thickness uniformity. SOI technology was used in the detector fabrication. The detector was designed to be used as a ΔE detector in a silicon telescope for measuring solar energetic particles in space. The detector thickness was specified to be 20 μm with an rms thickness uniformity of±0.5%. The active area consists of three separate elements, a round centre area and two surrounding annular segments. A new method was developed for measuring the thickness uniformity based on a modified Fizeau interferometer. The thickness uniformity specification was well met with the measured rms thickness variation of 43 nm. The detector was electrically characterized by measuring the I- V and C- V curves and the performance was verified using a 241Am alpha source.

  7. 3D silicon sensors: Design, large area production and quality assurance for the ATLAS IBL pixel detector upgrade

    NASA Astrophysics Data System (ADS)

    Da Via, Cinzia; Boscardin, Maurizio; Dalla Betta, Gian-Franco; Darbo, Giovanni; Fleta, Celeste; Gemme, Claudia; Grenier, Philippe; Grinstein, Sebastian; Hansen, Thor-Erik; Hasi, Jasmine; Kenney, Chris; Kok, Angela; Parker, Sherwood; Pellegrini, Giulio; Vianello, Elisa; Zorzi, Nicola

    2012-12-01

    3D silicon sensors, where electrodes penetrate the silicon substrate fully or partially, have successfully been fabricated in different processing facilities in Europe and USA. The key to 3D fabrication is the use of plasma micro-machining to etch narrow deep vertical openings allowing dopants to be diffused in and form electrodes of pin junctions. Similar openings can be used at the sensor's edge to reduce the perimeter's dead volume to as low as ˜4 μm. Since 2009 four industrial partners of the 3D ATLAS R&D Collaboration started a joint effort aimed at one common design and compatible processing strategy for the production of 3D sensors for the LHC Upgrade and in particular for the ATLAS pixel Insertable B-Layer (IBL). In this project, aimed for installation in 2013, a new layer will be inserted as close as 3.4 cm from the proton beams inside the existing pixel layers of the ATLAS experiment. The detector proximity to the interaction point will therefore require new radiation hard technologies for both sensors and front end electronics. The latter, called FE-I4, is processed at IBM and is the biggest front end of this kind ever designed with a surface of ˜4 cm2. The performance of 3D devices from several wafers was evaluated before and after bump-bonding. Key design aspects, device fabrication plans and quality assurance tests during the 3D sensors prototyping phase are discussed in this paper.

  8. A high quality voice coder with integrated echo canceller and voice activity detector for mobile satellite applications

    NASA Technical Reports Server (NTRS)

    Kondoz, A. M.; Evans, B. G.

    1993-01-01

    In the last decade, low bit rate speech coding research has received much attention resulting in newly developed, good quality, speech coders operating at as low as 4.8 Kb/s. Although speech quality at around 8 Kb/s is acceptable for a wide variety of applications, at 4.8 Kb/s more improvements in quality are necessary to make it acceptable to the majority of applications and users. In addition to the required low bit rate with acceptable speech quality, other facilities such as integrated digital echo cancellation and voice activity detection are now becoming necessary to provide a cost effective and compact solution. In this paper we describe a CELP speech coder with integrated echo canceller and a voice activity detector all of which have been implemented on a single DSP32C with 32 KBytes of SRAM. The quality of CELP coded speech has been improved significantly by a new codebook implementation which also simplifies the encoder/decoder complexity making room for the integration of a 64-tap echo canceller together with a voice activity detector.

  9. A high quality voice coder with integrated echo canceller and voice activity detector for mobile satellite applications

    NASA Astrophysics Data System (ADS)

    Kondoz, A. M.; Evans, B. G.

    In the last decade, low bit rate speech coding research has received much attention resulting in newly developed, good quality, speech coders operating at as low as 4.8 Kb/s. Although speech quality at around 8 Kb/s is acceptable for a wide variety of applications, at 4.8 Kb/s more improvements in quality are necessary to make it acceptable to the majority of applications and users. In addition to the required low bit rate with acceptable speech quality, other facilities such as integrated digital echo cancellation and voice activity detection are now becoming necessary to provide a cost effective and compact solution. In this paper we describe a CELP speech coder with integrated echo canceller and a voice activity detector all of which have been implemented on a single DSP32C with 32 KBytes of SRAM. The quality of CELP coded speech has been improved significantly by a new codebook implementation which also simplifies the encoder/decoder complexity making room for the integration of a 64-tap echo canceller together with a voice activity detector.

  10. Method of making large area conformable shape structures for detector/sensor applications using glass drawing technique and postprocessing

    SciTech Connect

    Ivanov, Ilia N.; Simpson, John T.

    2012-01-24

    A method of making a large area conformable shape structure comprises drawing a plurality of tubes to form a plurality of drawn tubes, and cutting the plurality of drawn tubes into cut drawn tubes of a predetermined shape. The cut drawn tubes have a first end and a second end along the longitudinal direction of the cut drawn tubes. The method further comprises conforming the first end of the cut drawn tubes into a predetermined curve to form the large area conformable shape structure, wherein the cut drawn tubes contain a material.

  11. Cometary activity, discrete outgassing areas, and dust-jet formation

    NASA Technical Reports Server (NTRS)

    Sekanina, Z.

    1991-01-01

    Conceptual models for various types of features observed in cometary comae (jets, spirals, halos, fans, etc.), their computer simulation, and the hydrodynamic models for jet formation are critically reviewed, and evidence for anisotropic, strongly collimated flows of ejecta emanating from discrete active regions (vents) on the rotating cometary nuclei is presented. Techniques employed to generate synthetic comet images that simulate the features observed are described, and their relevance to the primary objects of coma-morphology studies is discussed. Modeling of temporal variations in the water emission from discrete active regions suggests that production curves asymmetric with respect to perihelion should be commonplace. Critical comparisons with the activity profiles of Enke's comet and with light curves of disappearing comets and comets that undergo outbursts are presented. Recent developments in the understanding of the processes that cause the nongravitational perturbations of cometary motions are reviewed, and the observed discontinuities are identified with the birth of new sources and/or deactivation of old vents.

  12. Coherent Bremsstrahlung effect observed during STEM analysis of dopant distribution in silicon devices using large area silicon drift EDX detectors and high brightness electron source.

    PubMed

    Pantel, R

    2011-11-01

    In this paper, during dopant analysis of silicon devices, we have observed a phenomenon generally neglected in EDX analysis: the coherent Bremsstrahlung (CB). We discussed the reason why and came to the conclusion that the analytical TEM used for these experiments presents a configuration and performances, which makes this equipment very sensitive to the CB effect. This is due to large collection solid angle and high counting rate of the four silicon drift EDX detectors (SDD), a high brightness electron source providing large probe current and moreover a geometry favorable to on axis crystal observations. We analyzed silicon devices containing Si [110] and Si [100] crystal areas at different energies (80-120-200keV). We also observed relaxed SiGe (27 and 40at% of Ge). The CB effect, whose intensity is maximum near zone axis beam alignment, manifests as characteristic broad peaks present in the X-ray spectrum background. The peak energies are predicted by a simple formula deduced for the CB models found in the literature and that we present simply. We evaluate also the CB peak intensities and discuss the importance of this effect on the detection and quantification traces of impurities. The CB peaks also give information on the analyzed crystal structure (measurement of the periodicity along the zone axis) and allow, in every particular experiment or system, to determine the median take off angle of the EDX detectors. PMID:21946001

  13. Areas of Unsolved Problems in Caribbean Active Tectonics

    NASA Astrophysics Data System (ADS)

    Mann, P.

    2015-12-01

    I review some unsolved problems in Caribbean active tectonics. At the regional and plate scale: 1) confirm the existence of intraplate deformation zones of the central Caribbean plate that are within the margin of error of ongoing GPS measurements; 2) carry out field studies to evaluate block models versus models for distributed fault shear on the densely populated islands of Jamaica, Hispaniola, Puerto Rico, and the Virgin Islands; 3) carry out paleoseismological research of key plate boundary faults that may have accumulated large strains but have not been previously studied in detail; 4) determine the age of onset and far-field effects of the Cocos ridge and the Central America forearc sliver; 4) investigate the origin and earthquake-potential of obliquely-sheared rift basins along the northern coast of Venezuela; 5) determine the age of onset and regional active, tectonic effects of the Panama-South America collision including the continued activation of the Maracaibo block; and 6) validate longterm rates on active subduction zones with improving, tomographic maps of subducted slabs. At the individual fault scale: 1) determine the mode of termination of large and active strike -slip faults and application of the STEP model (Septentrional, Polochic, El Pilar, Bocono, Santa Marta-Bucaramanaga); 2) improve the understanding of the earthquake potential on the Enriquillo-Plantain Garden fault zone given "off-fault" events such as the 2010 Haiti earthquake; how widespread is this behavior?; and 3) estimate size of future tsunamis from studies of historic or prehistoric slump scars and mass transport deposits; what potential runups can be predicted from this information?; and 4) devise ways to keep rapidly growing, circum-Caribbean urban populations better informed and safer in the face of inevitable and future, large earthquakes.

  14. High-energy detector

    DOEpatents

    Bolotnikov, Aleksey E.; Camarda, Giuseppe; Cui, Yonggang; James, Ralph B.

    2011-11-22

    The preferred embodiments are directed to a high-energy detector that is electrically shielded using an anode, a cathode, and a conducting shield to substantially reduce or eliminate electrically unshielded area. The anode and the cathode are disposed at opposite ends of the detector and the conducting shield substantially surrounds at least a portion of the longitudinal surface of the detector. The conducting shield extends longitudinally to the anode end of the detector and substantially surrounds at least a portion of the detector. Signals read from one or more of the anode, cathode, and conducting shield can be used to determine the number of electrons that are liberated as a result of high-energy particles impinge on the detector. A correction technique can be implemented to correct for liberated electron that become trapped to improve the energy resolution of the high-energy detectors disclosed herein.

  15. Detectors for Particle Radiation

    NASA Astrophysics Data System (ADS)

    Kleinknecht, Konrad

    1999-01-01

    This textbook provides a clear, concise and comprehensive review of the physical principles behind the devices used to detect charged particles and gamma rays, and the construction and performance of these many different types of detectors. Detectors for high-energy particles and radiation are used in many areas of science, especially particle physics and nuclear physics experiments, nuclear medicine, cosmic ray measurements, space sciences and geological exploration. This second edition includes all the latest developments in detector technology, including several new chapters covering micro-strip gas chambers, silicion strip detectors and CCDs, scintillating fibers, shower detectors using noble liquid gases, and compensating calorimeters for hadronic showers. This well-illustrated textbook contains examples from the many areas in science in which these detectors are used. It provides both a coursebook for students in physics, and a useful introduction for researchers in other fields.

  16. Microparticle impact calibration of the Arrayed Large-Area Dust Detectors in INterplanetary space (ALADDIN) onboard the solar power sail demonstrator IKAROS

    NASA Astrophysics Data System (ADS)

    Hirai, Takayuki; Cole, Michael J.; Fujii, Masayuki; Hasegawa, Sunao; Iwai, Takeo; Kobayashi, Masanori; Srama, Ralf; Yano, Hajime

    2014-10-01

    The Arrayed Large-Area Dust Detectors in INterplanetary space (ALADDIN) is an array of polyvinylidene fluoride (PVDF) based dust detectors aboard the solar power sail demonstrator named IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun). The total sensor area of ALADDIN (0.54 m2) is the world's largest among the past PVDF-based dust detectors. IKAROS was launched in May 2010 and then ALADDIN measured cosmic dust impacts for 16 months while orbiting around between 0.7 and 1.1 AU. The main scientific objective of ALADDIN is to reveal number density of ≥10-μm-sized dust in the zodiacal cloud with much higher time-space resolution than that achieved by any past in-situ measurements. The distribution of ≥10-μm-sized dust can be also observed mainly with the light scattering by optical instruments. This paper gives the scientific objectives, the instrumental description, and the results of microparticle impact calibration of ALADDIN conducted in ground laboratories. For the calibration tests we used Van de Graaf accelerators (VdG), two-stage light gas guns (LGG), and a nano-second pulsed Nd:YAG laser (nsPL). Through these experiments, we obtained depolarization charge signal caused by hypervelocity impacts or laser irradiation using the flight spare of 20-μm-thick PVDF sensor and the electronics box of ALADDIN. In the VdG experiment we accelerated iron, carbon, and silver microparticles at 1-30 km/s, while in the LGG experiment we performed to shoot 100's-μm-sized particles of soda-lime glass and stainless steel at 3-7 km/s as single projectile. For interpolation to ≥10-μm size, we irradiated infrared laser at the energy of 15-20 mJ directly onto the PVDF sensor. From the signal analysis, we developed a calibration law for estimation of masses of impacted dust particles. The dynamic range of ALADDIN corresponds from 9×10-14 kg to 2×10-10 kg (4-56 μm in diameter at density of 2.0 g/cm3) at the expected impact velocity of 10 km/s at 1 AU

  17. Spot temperatures and area coverages on active dwarf stars

    NASA Technical Reports Server (NTRS)

    Sarr, Steven H.; Neff, James E.

    1990-01-01

    Two active K dwarfs are examined to determine the temperatures of the stars and to estimate the locations and sizes of cool spots on the stellar surfaces. Two wavelength regions with TiO absorption bands at different temperature sensitivities are modeled simultaneously using the method developed by Huenemoerder and Ramsey (1987). The spectrum of BD +26deg730 shows excess absorption in the TiO band, and the absence of the 8860 A band in HD 82558 indicates that its spots are warmer than those of BD +26deg730.

  18. Atomic ionization by sterile-to-active neutrino conversion and constraints on dark matter sterile neutrinos with germanium detectors

    NASA Astrophysics Data System (ADS)

    Chen, Jiunn-Wei; Chi, Hsin-Chang; Lin, Shin-Ted; Liu, C.-P.; Singh, Lakhwinder; Wong, Henry T.; Wu, Chih-Liang; Wu, Chih-Pan

    2016-05-01

    The transition magnetic moment of a sterile neutrino can give rise to its conversion to an active neutrino through radiative decay or nonstandard interaction (NSI) with matter. For sterile neutrinos of keV-mass as dark matter candidates, their decay signals are actively searched for in cosmic x-ray spectra. In this work, we consider the NSI that leads to atomic ionization, which can be detected by direct dark matter experiments. It is found that this inelastic scattering process for a nonrelativistic sterile neutrino has a pronounced enhancement in the differential cross section at energy transfer about half of its mass, manifesting experimentally as peaks in the measurable energy spectra. The enhancement effects gradually smear out as the sterile neutrino becomes relativistic. Using data taken with low-threshold low-background germanium detectors, constraints on sterile neutrino mass and its transition magnetic moment are derived and compared with those from astrophysical observations.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  20. Agriculture in an area impacted by past uranium mining activities

    SciTech Connect

    Carvalho, F. P.; Oliveira, J. M.; Neves, O.; Vicente, E. M.; Abreu, M. M.

    2007-07-01

    The shallow aquifer near the old Cunha Baixa uranium mine (Viseu, Portugal) was contaminated by acid mine drainage. Concentration of radionuclides in water from irrigation wells and in the topsoil layer of the agriculture fields nearby display enhanced concentrations of uranium, radium and polonium. Two types of agriculture land in this area were selected, one with enhanced and another with low uranium concentrations, for controlled growth of lettuce and potatoes. Plants were grown in replicate portions of land (two plots) in each soil type and were periodically irrigated with water from wells. In each soil, one plot was irrigated with water containing low concentration of dissolved uranium and the other plot with water containing enhanced concentration of dissolved uranium. At the end of the growth season, plants were harvested and analysed, along with soil and irrigation water samples. Results show the accumulation of radionuclides in edible parts of plants, specially in the field plots with higher radionuclide concentrations in soil. Radionuclides in irrigation water contributed less to the radioactivity accumulated in plants than radionuclides from soils. (authors)

  1. On communicating earthquake risk in low-activity areas

    NASA Astrophysics Data System (ADS)

    Gaspar-Escribano, J. M.; García Rodríguez, M. J.; Rivas-Medina, A.; Benito, B.; Wachowicz, M.; Bernabé, M. A.; Iturrioz, T.

    2009-04-01

    The assessment of natural risks for emergency response and preparedness planning is a transversal discipline that can be studied from many perspectives, including social, political and earth sciences. Accordingly, people with different profiles and backgrounds working on the topic should use of a common language in order to avoid misunderstandings, improve information dissemination, and at the end, facilitate preparedness and response measurements in the right direction. Some ideas aimed at identifying communication barriers between all parties and suppressing them are presented, using the example of regional seismic risk studies of low-hazard areas, where the rare occurrence of destructive events complicates the situation. First, factors related to the actual awareness, the degree of understanding and the interest for getting the information about a given a natural risk, are analyzed taking into account that they differ from user to user (civil protection official, scientist, general public). Subsequently, choices of parameters used to typify seismic risk and ways of representing them graphically are proposed. Finally, whether the incidence of the lack of a common language increases risk vulnerability is discussed.

  2. Design and Preliminary Monte Carlo Calculations of an Active Compton Suppressed LaBr3(Ce) Detector System for TRU Assay in Remote-Handled Wastes

    SciTech Connect

    J. Kulisek; J. K. Hartwell; M. E. McIlwain; R. P. Gardner

    2006-09-01

    Recent studies indicate LaBr3(Ce) scintillation detectors have desirable attributes, such as room temperature operability, which may make them viable alternatives as primary detectors (PD) in a Compton suppression spectrometer (CSS) used for remote-handled transuranic (RH-TRU) waste assay. A CSS with a LaBr3(Ce) PD has been designed and its expected performance evaluated using Monte Carlo analysis. The unique design of this unit minimizes the amount of "dead" material between the PD and the secondary guard detector. The analysis results indicate that this detector will have a relatively high Compton-suppression capability, with greater suppression ability for large angle-scattered photons in the PD. J. K. Hartwell1, M. E. McIlwain1, R. P. Gardner2, J. Kulisek3 1) Idaho National Laboratory, PO Box 1625, Idaho Falls, ID 83415-2114 USA 2) North Carolina State University, Dept of Nuclear Eng., PO Box 7909, Raleigh, NC 27695 USA 3) Ohio State University, Columbus, Ohio 43210 The US Department of Energy’s transuranic (TRU) waste inventory includes about 4,500 m3 of remote-handled TRU (RH-TRU) wastes. The RH-TRU waste stream is composed of a variety of containerized waste forms having a contact surface dose rate that exceeds 2 mSv/hr (200 mrem/hr) containing waste materials with a total TRU concentration greater than 3700 Bq/g (100 nCi/g). As part of a research project to investigate the use of active Compton-suppressed room-temperature gamma-ray detectors for direct non-destructive quantification of the TRU content of these RH-TRU wastes, we have designed and purchased a unique detector system using a LaBr3(Ce) primary detector and a NaI(Tl) suppression mantle. The expected detector performance has been modeled using MCNP-X [1] and CEARCPG [2], and incorporates certain design features modeled as important to active Compton suppression systems in previously-published work [3]. The unique detector system is sketched in Fig. 1. The ~25 mm diameter by 75 mm long LaBr3(Ce

  3. Characteristics and application of spherical-type activation detectors in neutron spectrum measurements at a boron neutron capture therapy (BNCT) facility

    NASA Astrophysics Data System (ADS)

    Lin, Heng-Xiao; Chen, Wei-Lin; Liu, Yuan-Hao; Sheu, Rong-Jiun

    2016-03-01

    A set of spherical-type activation detectors was developed aiming to provide better determination of the neutron spectrum at the Tsing Hua Open-pool Reactor (THOR) BNCT facility. An activation foil embedded in a specially designed spherical holder exhibits three advantages: (1) minimizing the effect of neutron angular dependence, (2) creating response functions with broadened coverage of neutron energies by introducing additional moderators or absorbers to the central activation foil, and (3) reducing irradiation time because of improved detection efficiencies to epithermal neutron beam. This paper presents the design concept and the calculated response functions of new detectors. Theoretical and experimental demonstrations of the performance of the detectors are provided through comparisons of the unfolded neutron spectra determined using this method and conventional multiple-foil activation techniques.

  4. Mountain-Plains Master Course List. Curriculum Areas: Job Titles: Learning Activity Packages: Courses: Units.

    ERIC Educational Resources Information Center

    Mountain-Plains Education and Economic Development Program, Inc., Glasgow AFB, MT.

    The document contains a master listing of all Mountain-Plains curriculum, compiled by job title, course, unit and LAP (Learning Activity Package), and arranged in numerical order by curriculum area. Preceding each curriculum area is a page of explanatory notes describing the curriculum area and including relevant job descriptions. Where a job…

  5. 33 CFR 334.761 - Naval Support Activity Panama City; St. Andrews Bay; restricted areas.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... City; St. Andrews Bay; restricted areas. 334.761 Section 334.761 Navigation and Navigable Waters CORPS... REGULATIONS § 334.761 Naval Support Activity Panama City; St. Andrews Bay; restricted areas. (a) The areas—(1... in this section shall be enforced by the Commanding Officer, Naval Support Activity, Panama...

  6. 32 CFR Appendix C to Part 552 - Authorized Activities for Fort Lewis Maneuver Area Access

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 3 2011-07-01 2009-07-01 true Authorized Activities for Fort Lewis Maneuver Area Access C Appendix C to Part 552 National Defense Department of Defense (Continued) DEPARTMENT OF.... 552, App. C Appendix C to Part 552—Authorized Activities for Fort Lewis Maneuver Area Access...

  7. Communicating Astronomy in a Metropolis and Disaster Area - Activities of the Tenpla Project

    NASA Astrophysics Data System (ADS)

    Kamegai, K.; Takanashi, N.; Hiramatsu, M.; Naito, S.

    2015-03-01

    We present recent activities delivering astronomy to the public by the Tenpla project in Japan. One is voluntary activities in the disaster area of the Great East Japan Earthquake. The other is holding tens of star parties and public lectures in the central area of Tokyo.

  8. 34 CFR 75.608 - Areas in the facilities for cultural activities.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 1 2010-07-01 2010-07-01 false Areas in the facilities for cultural activities. 75.608 Section 75.608 Education Office of the Secretary, Department of Education DIRECT GRANT PROGRAMS What Conditions Must Be Met by a Grantee? Construction § 75.608 Areas in the facilities for cultural activities....

  9. 34 CFR 75.608 - Areas in the facilities for cultural activities.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 34 Education 1 2011-07-01 2011-07-01 false Areas in the facilities for cultural activities. 75.608 Section 75.608 Education Office of the Secretary, Department of Education DIRECT GRANT PROGRAMS What Conditions Must Be Met by a Grantee? Construction § 75.608 Areas in the facilities for cultural activities....

  10. 34 CFR 75.608 - Areas in the facilities for cultural activities.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 34 Education 1 2014-07-01 2014-07-01 false Areas in the facilities for cultural activities. 75.608 Section 75.608 Education Office of the Secretary, Department of Education DIRECT GRANT PROGRAMS What Conditions Must Be Met by a Grantee? Construction § 75.608 Areas in the facilities for cultural activities....

  11. 34 CFR 75.608 - Areas in the facilities for cultural activities.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 34 Education 1 2012-07-01 2012-07-01 false Areas in the facilities for cultural activities. 75.608 Section 75.608 Education Office of the Secretary, Department of Education DIRECT GRANT PROGRAMS What Conditions Must Be Met by a Grantee? Construction § 75.608 Areas in the facilities for cultural activities....

  12. 34 CFR 75.608 - Areas in the facilities for cultural activities.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 34 Education 1 2013-07-01 2013-07-01 false Areas in the facilities for cultural activities. 75.608 Section 75.608 Education Office of the Secretary, Department of Education DIRECT GRANT PROGRAMS What Conditions Must Be Met by a Grantee? Construction § 75.608 Areas in the facilities for cultural activities....

  13. Research activities in nuclear astrophysics and related areas

    NASA Technical Reports Server (NTRS)

    1996-01-01

    NASA/GRO grant NAG 5-2081, at the University of Chicago, has provided support for a broad program of theoretical research in nuclear astrophysics and related areas, with regard to gamma-ray and hard X-ray emission from classical nova explosions. This research emphasized the possible detection of 22Na gamma-ray line emission from nearby novae involving ONeMg white dwarfs, the detailed examination of 26Al production in novae, and the possible detection of the predicted early gamma ray emission from novae that arises from the decay of the short lived, positron emitting isotopes of CNO elements. Studies of nova related problems have consumed an increasing fraction of the Principal Investigator's research efforts over the past decade. Current research addresses problems associated with the standard model for the outbursts of the classical novae: the occurrence of thermonuclear runaways (TNR) in the accreted hydrogen rich envelopes on white dwarfs in close binary systems (see, e.g., the reviews by Truran 1982; and Shara 1989). Research in progress and planned for the next three years has three main objectives: (1) to gain an improved understanding of the early evolution of the light curves of, particularly, the fastest novae; (2) to gain an improved understanding of the relative importance of the various possible mechanisms of envelope hydrogen depletion (e.g. winds, common envelope driven mass loss, and nuclear burning) to the long term evolution of novae in outburst; and (3) to seek to provide a somewhat more definitive statement of the role of classical novae in nucleosynthesis. Our proposed 2-D studies of convection during the early phases of the TNR and our systematic attempt to incorporate an improved treatment of radiation hydrodynamics into the hydrodynamic code utilized in our calculations, are particularly relevant to the first of these objectives. Further 2-D studies of the effects of common envelope evolution are intended to provide more realistic constraints

  14. The Simbol-X Low Energy Detector

    SciTech Connect

    Lechner, Peter

    2009-05-11

    For the Low Energy Detector of Simbol-X a new type of active pixel sensor based on the integrated amplifier DEPFET has been developed. This concept combines large area, scalable pixel size, low noise, and ultra-fast readout. Flight representative prototypes have been processed with a performance matching the Simbol-X specifications and demonstrating the technology readiness.

  15. Impact of active material surface area on thermal stability of LiCoO2 cathode

    NASA Astrophysics Data System (ADS)

    Geder, Jan; Hoster, Harry E.; Jossen, Andreas; Garche, Jürgen; Yu, Denis Y. W.

    2014-07-01

    Thermal stability of charged LiCoO2 cathodes with various surface areas of active material is investigated in order to quantify the effect of LiCoO2 surface area on thermal stability of cathode. Thermogravimetric analyses and calorimetry have been conducted on charged cathodes with different active material surface areas. Besides reduced thermal stability, high surface area also changes the active material decomposition reaction and induces side reactions with additives. Thermal analyses of LiCoO2 delithiated chemically without any additives or with a single additive have been conducted to elaborate the effect of particle size on side reactions. Stability of cathode-electrolyte system has been investigated by accelerating rate calorimetry (ARC). Arrhenius activation energy of cathode decomposition has been calculated as function of conversion at different surface area of active material.

  16. A novel method for the activity measurement of large-area beta reference sources.

    PubMed

    Stanga, D; De Felice, P; Keightley, J; Capogni, M; Ioan, M R

    2016-03-01

    A novel method has been developed for the activity measurement of large-area beta reference sources. It makes use of two emission rate measurements and is based on the weak dependence between the source activity and the activity distribution for a given value of transmission coefficient. The method was checked experimentally by measuring the activity of two ((60)Co and (137)Cs) large-area reference sources constructed from anodized aluminum foils. Measurement results were compared with the activity values measured by gamma spectrometry. For each source, they agree within one standard uncertainty and also agree within the same limits with the certified values of the source activity. PMID:26701656

  17. A Finger-Pressing Position Detector for Assisting People with Developmental Disabilities to Control Their Environmental Stimulation through Fine Motor Activities with a Standard Keyboard

    ERIC Educational Resources Information Center

    Shih, Ching-Hsiang

    2012-01-01

    This study used a standard keyboard with a newly developed finger-pressing position detection program (FPPDP), i.e. a new software program, which turns a standard keyboard into a finger-pressing position detector, to evaluate whether two people with developmental disabilities would be able to actively perform fine motor activities to control their…

  18. Soil gas radon-thoron monitoring in Dharamsala area of north-west Himalayas, India using solid state nuclear track detectors

    NASA Astrophysics Data System (ADS)

    Kumar, Gulshan; Kumar, Arvind; Walia, Vivek; Kumar, Jitender; Gupta, Vikash; Yang, Tsanyao Frank; Singh, Surinder; Bajwa, Bikramjit Singh

    2013-10-01

    The study described here is based on the measurements of soil gas radon-thoron concentrations performed at Dharamsala region of north-west (NW) Himalayas, India. The study area is tectonically and environmentally significant and shows the features of ductile shear zone due to the presence of distinct thrust planes. Solid state nuclear track detectors (LR-115 films) have been used for the soil gas radon-thoron monitoring. Twenty five radon-thoron discriminators with LR-115 films were installed in the borehole of about 50 cm in the study areas. The recorded radon concentration varies from 1593 to 13570 Bq/m3 with an average value of 5292 Bq/m3. The recorded thoron concentration varies from 223 to 2920 Bq/m3 with an average value of 901 Bq/m3. The anomalous value of radon-thoron has been observed near to the faults like main boundary thrust (MBT and MBT2) as well as neotectonic lineaments in the region.

  19. 33 CFR 334.761 - Naval Support Activity Panama City; St. Andrews Bay; restricted areas.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... City; St. Andrews Bay; restricted areas. 334.761 Section 334.761 Navigation and Navigable Waters CORPS... REGULATIONS § 334.761 Naval Support Activity Panama City; St. Andrews Bay; restricted areas. (a) The areas—(1... waterline to 30°09′57.5″ N, 085°44′37″ W; then northerly to point of origin. (2) Area BA-1. The area...

  20. 33 CFR 334.761 - Naval Support Activity Panama City; St. Andrews Bay; restricted areas.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... City; St. Andrews Bay; restricted areas. 334.761 Section 334.761 Navigation and Navigable Waters CORPS... REGULATIONS § 334.761 Naval Support Activity Panama City; St. Andrews Bay; restricted areas. (a) The areas—(1... waterline to 30°09′57.5″ N, 085°44′37″ W; then northerly to point of origin. (2) Area BA-1. The area...

  1. SU-E-I-53: Comparison of Kerma-Area-Product Between the Micro-Angiographic Fluoroscope (MAF) and a Flat Panel Detector (FPD) as Used in Neuro-Endovascular Procedures

    SciTech Connect

    Vijayan, S; Rana, V; Nagesh, S Setlur; Xiong, Z; Rudin, S; Bednarek, D

    2015-06-15

    Purpose: To determine the reduction of integral dose to the patient when using the micro-angiographic fluoroscope (MAF) compared to when using the standard flat-panel detector (FPD) for the techniques used during neurointerventional procedures. Methods: The MAF is a small field-of-view, high resolution x-ray detector which captures 1024 x 1024 pixels with an effective pixel size of 35μm and is capable of real-time imaging up to 30 frames per second. The MAF was used in neuro-interventions during those parts of the procedure when high resolution was needed and the FPD was used otherwise. The technique parameters were recorded when each detector was used and the kerma-area-product (KAP) per image frame was determined. KAP values were calculated for seven neuro interventions using premeasured calibration files of output as a function of kVp and beam filtration and included the attenuation of the patient table for the frontal projections to be more representative of integral patient dose. The air kerma at the patient entrance was multiplied by the beam area at that point to obtain the KAP values. The ranges of KAP values per frame were determined for the range of technique parameters used during the clinical procedures. To appreciate the benefit of the higher MAF resolution in the region of interventional activity, DA technique parameters were generally used with the MAF. Results: The lowest and highest values of KAP per frame for the MAF in DA mode were 4 and 50 times lower, respectively, compared to those of the FPD in pulsed fluoroscopy mode. Conclusion: The MAF was used in those parts of the clinical procedures when high resolution and image quality was essential. The integral patient dose as represented by the KAP value was substantially lower when using the MAF than when using the FPD due to the much smaller volume of tissue irradiated. This research was supported in part by Toshiba Medical Systems Corporation and NIH Grant R01EB002873.

  2. Decreased Activation of Subcortical Brain Areas in the Motor Fatigue State: An fMRI Study.

    PubMed

    Hou, Li J; Song, Zheng; Pan, Zhu J; Cheng, Jia L; Yu, Yong; Wang, Jun

    2016-01-01

    One aspect of motor fatigue is the exercise-induced reduction of neural activity to voluntarily drive the muscle or muscle group. Functional magnetic resonance imaging provides access to investigate the neural activation on the whole brain level and studies observed changes of activation intensity after exercise-induced motor fatigue in the sensorimotor cortex. However, in human, little evidence exists to demonstrate the role of subcortical brain regions in motor fatigue, which is contradict to abundant researches in rodent indicating that during simple movement, the activity of the basal ganglia is modulated by the state of motor fatigue. Thus, in present study, we explored the effect of motor fatigue on subcortical areas in human. A series of fMRI data were collected from 11 healthy subjects while they were executing simple motor tasks in two conditions: before and under the motor fatigue state. The results showed that in both conditions, movements evoked activation volumes in the sensorimotor areas, SMA, cerebellum, thalamus, and basal ganglia. Of primary importance are the results that the intensity and size of activation volumes in the subcortical areas (i.e., thalamus and basal ganglia areas) are significantly decreased during the motor fatigue state, implying that motor fatigue disturbs the motor control processing in a way that both sensorimotor areas and subcortical brain areas are less active. Further study is needed to clarify how subcortical areas contribute to the overall decreased activity of CNS during motor fatigue state. PMID:27536264

  3. Decreased Activation of Subcortical Brain Areas in the Motor Fatigue State: An fMRI Study

    PubMed Central

    Hou, Li J.; Song, Zheng; Pan, Zhu J.; Cheng, Jia L.; Yu, Yong; Wang, Jun

    2016-01-01

    One aspect of motor fatigue is the exercise-induced reduction of neural activity to voluntarily drive the muscle or muscle group. Functional magnetic resonance imaging provides access to investigate the neural activation on the whole brain level and studies observed changes of activation intensity after exercise-induced motor fatigue in the sensorimotor cortex. However, in human, little evidence exists to demonstrate the role of subcortical brain regions in motor fatigue, which is contradict to abundant researches in rodent indicating that during simple movement, the activity of the basal ganglia is modulated by the state of motor fatigue. Thus, in present study, we explored the effect of motor fatigue on subcortical areas in human. A series of fMRI data were collected from 11 healthy subjects while they were executing simple motor tasks in two conditions: before and under the motor fatigue state. The results showed that in both conditions, movements evoked activation volumes in the sensorimotor areas, SMA, cerebellum, thalamus, and basal ganglia. Of primary importance are the results that the intensity and size of activation volumes in the subcortical areas (i.e., thalamus and basal ganglia areas) are significantly decreased during the motor fatigue state, implying that motor fatigue disturbs the motor control processing in a way that both sensorimotor areas and subcortical brain areas are less active. Further study is needed to clarify how subcortical areas contribute to the overall decreased activity of CNS during motor fatigue state. PMID:27536264

  4. Functional Specificity of the Visual Word Form Area: General Activation for Words and Symbols but Specific Network Activation for Words

    ERIC Educational Resources Information Center

    Reinke, Karen; Fernandes, Myra; Schwindt, Graeme; O'Craven, Kathleen; Grady, Cheryl L.

    2008-01-01

    The functional specificity of the brain region known as the Visual Word Form Area (VWFA) was examined using fMRI. We explored whether this area serves a general role in processing symbolic stimuli, rather than being selective for the processing of words. Brain activity was measured during a visual 1-back task to English words, meaningful symbols…

  5. Individual Human Brain Areas Can Be Identified from Their Characteristic Spectral Activation Fingerprints.

    PubMed

    Keitel, Anne; Gross, Joachim

    2016-06-01

    The human brain can be parcellated into diverse anatomical areas. We investigated whether rhythmic brain activity in these areas is characteristic and can be used for automatic classification. To this end, resting-state MEG data of 22 healthy adults was analysed. Power spectra of 1-s long data segments for atlas-defined brain areas were clustered into spectral profiles ("fingerprints"), using k-means and Gaussian mixture (GM) modelling. We demonstrate that individual areas can be identified from these spectral profiles with high accuracy. Our results suggest that each brain area engages in different spectral modes that are characteristic for individual areas. Clustering of brain areas according to similarity of spectral profiles reveals well-known brain networks. Furthermore, we demonstrate task-specific modulations of auditory spectral profiles during auditory processing. These findings have important implications for the classification of regional spectral activity and allow for novel approaches in neuroimaging and neurostimulation in health and disease. PMID:27355236

  6. Individual Human Brain Areas Can Be Identified from Their Characteristic Spectral Activation Fingerprints

    PubMed Central

    Keitel, Anne; Gross, Joachim

    2016-01-01

    The human brain can be parcellated into diverse anatomical areas. We investigated whether rhythmic brain activity in these areas is characteristic and can be used for automatic classification. To this end, resting-state MEG data of 22 healthy adults was analysed. Power spectra of 1-s long data segments for atlas-defined brain areas were clustered into spectral profiles (“fingerprints”), using k-means and Gaussian mixture (GM) modelling. We demonstrate that individual areas can be identified from these spectral profiles with high accuracy. Our results suggest that each brain area engages in different spectral modes that are characteristic for individual areas. Clustering of brain areas according to similarity of spectral profiles reveals well-known brain networks. Furthermore, we demonstrate task-specific modulations of auditory spectral profiles during auditory processing. These findings have important implications for the classification of regional spectral activity and allow for novel approaches in neuroimaging and neurostimulation in health and disease. PMID:27355236

  7. 33 CFR 334.761 - Naval Support Activity Panama City; St. Andrews Bay; restricted areas.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Naval Support Activity Panama... REGULATIONS § 334.761 Naval Support Activity Panama City; St. Andrews Bay; restricted areas. (a) The areas—(1... in this section shall be enforced by the Commanding Officer, Naval Support Activity, Panama...

  8. 33 CFR 334.761 - Naval Support Activity Panama City; St. Andrews Bay; restricted areas.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Naval Support Activity Panama... REGULATIONS § 334.761 Naval Support Activity Panama City; St. Andrews Bay; restricted areas. (a) The areas—(1... in this section shall be enforced by the Commanding Officer, Naval Support Activity, Panama...

  9. Preparation of activated carbon with large specific surface area from reed black liquor.

    PubMed

    Sun, Y; Zhang, J P; Yang, G; Li, Z H

    2007-05-01

    Activated carbon with large specific surface area and well-developed porosity was prepared from pyrolysis of K2CO3-impregnated lignin precipitated from reed pulp black liquors. The impregnation ratio was 1:1. The effect of activation temperature upon the Brunauer-Emmett-Teller (BET) specific surface area and pore volume of the carbon was closely investigated. Increasing activation temperature led to an opening and widening of the porous structure below 800'C. Above 800'C, the excess widening of pore led to the decrease of BET surface area and micropore volume. The BET surface area and pore volume of the carbon activated at 800 degrees C were 1395 m(2) g(-1) and 0.7702 ml g(-1) , respectively. The potential application of the carbon activated at 800 degrees C for removal of Cr (VI) was also investigated. The experimental results showed that it had good adsorption capacity. PMID:17615958

  10. Improving global fire carbon emissions estimates by combining moderate resolution burned area and active fire observations

    NASA Astrophysics Data System (ADS)

    Randerson, J. T.; Chen, Y.; Giglio, L.; Rogers, B. M.; van der Werf, G.

    2011-12-01

    In several important biomes, including croplands and tropical forests, many small fires exist that have sizes that are well below the detection limit for the current generation of burned area products derived from moderate resolution spectroradiometers. These fires likely have important effects on greenhouse gas and aerosol emissions and regional air quality. Here we developed an approach for combining 1km thermal anomalies (active fires; MOD14A2) and 500m burned area observations (MCD64A1) to estimate the prevalence of these fires and their likely contribution to burned area and carbon emissions. We first estimated active fires within and outside of 500m burn scars in 0.5 degree grid cells during 2001-2010 for which MCD64A1 burned area observations were available. For these two sets of active fires we then examined mean fire radiative power (FRP) and changes in enhanced vegetation index (EVI) derived from 16-day intervals immediately before and after each active fire observation. To estimate the burned area associated with sub-500m fires, we first applied burned area to active fire ratios derived solely from within burned area perimeters to active fires outside of burn perimeters. In a second step, we further modified our sub-500m burned area estimates using EVI changes from active fires outside and within of burned areas (after subtracting EVI changes derived from control regions). We found that in northern and southern Africa savanna regions and in Central and South America dry forest regions, the number of active fires outside of MCD64A1 burned areas increased considerably towards the end of the fire season. EVI changes for active fires outside of burn perimeters were, on average, considerably smaller than EVI changes associated with active fires inside burn scars, providing evidence for burn scars that were substantially smaller than the 25 ha area of a single 500m pixel. FRP estimates also were lower for active fires outside of burn perimeters. In our

  11. Regular radon activity concentration and effective dose measurements inside the great pyramid with passive nuclear track detectors.

    PubMed

    Hafez, A F; Bishara, A A; Kotb, M A; Hussein, A S

    2003-08-01

    Radon activity concentrations and equilibrium factors inside the great pyramid of "Cheops" were measured with passive nuclear track detectors. The variation of these concentrations in location was investigated. Seasonal variation of radon activity concentrations with winter maximum and summer minimum were observed inside the pyramid. The 1-y average radon activity concentration ranged from a minimum of 20 to a maximum of 170 Bq m(-3). Results show that the yearly average equilibrium factor between radon and its progeny was assessed as 0.16 and 0.36 inside the pyramid and near entrance, respectively. Moreover, the estimated annual effective dose was 0.05 mSv to tour guides and varied from 0.19 to 0.36 mSv for the pyramid guards; for visitors the average effective dose was 0.15 microSv per visit. These are lower than the 3-10 mSv y(-1) dose limit recommend by ICRP 65. PMID:12938968

  12. Development of a wearable motion detector for telemonitoring and real-time identification of physical activity.

    PubMed

    Yang, Che-Chang; Hsu, Yeh-Liang

    2009-01-01

    Characteristics of physical activity are indicative of one's mobility level, latent chronic diseases, and aging process. Current research has been oriented to provide quantitative assessment of physical activity with ambulatory monitoring approaches. This study presents the design of a portable microprocessor-based accelerometry measuring device to implement real-time physical activity identification. An algorithm was developed to process real-time tri-axial acceleration signals produced by human movement to identify targeted still postures, postural transitions, and dynamic movements. Fall detection was also featured in this algorithm to meet the increasing needs of elderly care in free-living environments. High identification accuracy was obtained in performance evaluation. This device is technically viable for telemonitoring and real-time identification of physical activity, while providing sufficient information to evaluate a person's activity of daily living and her/his status of physical mobility. Limitations regarding real-time processing and implementation of the system for telemonitoring in the home environment were also observed. PMID:19199849

  13. Design and testing of an active quenching circuit for an avalanche photodiode photon detector

    NASA Technical Reports Server (NTRS)

    Arbel, D.; Schwartz, J. A.

    1991-01-01

    The photon-detection capabilities of avalanche photodiodes (APDs) operating above their theoretical breakdown voltages are described, with particular attention given to the needs and methods of quenching an avalanche once breakdown has occurred. A brief background on the motives of and previous work with this mode of operation is presented. Finally, a description of the design and testing of an active quenching circuit is given. Although the active quenching circuit did not perform as expected, knowledge was gained as to the signal amplitudes necessary for quenching and the need for a better model for the above-breakdown circuit characteristics of the Geiger-mode APD.

  14. Bayesian calibration of reactor neutron flux spectrum using activation detectors measurements: Application to CALIBAN reactor

    SciTech Connect

    Cartier, J.; Casoli, P.; Chappert, F.

    2013-07-01

    In this paper, we present calibration methods in order to estimate reactor neutron flux spectrum and its uncertainties by using integral activation measurements. These techniques are performed using Bayesian and MCMC framework. These methods are applied to integral activation experiments in the cavity of the CALIBAN reactor. We estimate the neutron flux and its related uncertainties. The originality of this work is that these uncertainties take into account measurements uncertainties, cross-sections uncertainties and model error. In particular, our results give a very good approximation of the total flux and indicate that neutron flux from MCNP simulation for energies above about 5 MeV seems to overestimate the 'real flux'. (authors)

  15. Application of epithermal neutron activation in multielement analysis of silicate rocks employing both coaxial Ge(Li) and low energy photon detector systems

    USGS Publications Warehouse

    Baedecker, P.A.; Rowe, J.J.; Steinnes, E.

    1977-01-01

    The instrumental activation analysis of silicate rocks using epithermal neutrons has been studied using both high resolution coaxial Ge(Li) detectors and low energy photon detectors, and applied to the determination of 23 elements in eight new U.S.G.S. standard rocks. The analytical use X-ray peaks associated with electron capture or internal conversion processes has been evaluated. Of 28 elements which can be considered to be determinable by instrumental means, the epithermal activation approach is capable of giving improved sensitivity and precision in 16 cases, over the normal INAA procedure. In eleven cases the use of the low energy photon detector is thought to show advantages over convertional coaxial Ge(Li) spectroscopy. ?? 1977 Akade??miai Kiado??.

  16. Prediction of prognosis of ALS: Importance of active denervation findings of the cervical-upper limb area and trunk area

    PubMed Central

    Sato, Yoko; Nakatani, Eiji; Watanabe, Yasuhiro; Fukushima, Masanori; Nakashima, Kenji; Kannagi, Mari; Kanatani, Yasuhiro; Mizushima, Hiroshi

    2015-01-01

    Summary Amyotrophic lateral sclerosis (ALS) is a motor neuron disease characterized by serious muscle atrophy and weakness. The purpose of this study was to find prognostic factors in patients with mild ALS using application forms for the Specified Disease Treatment Research Program in Japan. We classified ALS as mild, moderate and severe. The subjects consisted of 363 patients with mild ALS who underwent needle electromyography at registration and were followed for more than one year. Time to progression to severe ALS and time to deterioration of activities of daily living such as speech dysfunction, upper limb dysfunction, and walking disability were used as outcomes. Cox proportional hazards model analysis was performed to identify prognostic factors. Of the patients with initially mild ALS, 38.3% (139/363) had progressed severe ALS at the last follow-up. In multivariate analysis of time to progression to severe ALS, bulbar onset (hazard ratio [95% confidence interval]: 1.68 [1.13–2.49], p = 0.010), tongue atrophy (1.69 [1.14–2.51], p = 0.009), dyspnea (1.57 [1.02–2.41], p = 0.042) and active denervation findings (ADFs) of the cervical-upper limb area (1.81 [1.25–2.63], p = 0.002) emerged as prognostic factors. Furthermore ADFs in the trunk area were prognostic factors for upper limb dysfunction and walking disability (1.72 [1.05–2.81], p = 0.031, and 1.97 [1.09–3.59], p = 0.026). In conclusion ADFs of the cervical-upper limb area and trunk area were prognostic factors in ALS patients. PMID:26668778

  17. The HERMES Recoil Detector

    SciTech Connect

    Kaiser, R.

    2006-07-11

    The HERMES Collaboration is installing a new Recoil Detector to upgrade the spectrometer for measurements of hard exclusive electron/positron scattering reactions, in particular deeply virtual Compton scattering. These measurements will provide access to generalised parton distributions and hence to the localisation of quarks inside hadrons and to their orbital angular momentum. The HERMES Recoil Detector consists of three active components: a silicon detector surrounding the target cell inside the beam vacuum, a scintillating fibre tracker and a photon detector consisting of three layers of tungsten/scintillator. All three detectors are located inside a solenoidal magnetic field of 1 Tesla. The Recoil Detector was extensively tested with cosmic muons over the summer of 2005 and is being installed in the winter of 2005/6 for data taking until summer 2007.

  18. Development and applications of a new neutron single-crystal diffractometer based on a two-dimensional large-area curved position-sensitive detector.

    PubMed

    Lee, Chang-Hee; Noda, Yukio; Ishikawa, Yoshihisa; Kim, Shin Ae; Moon, Myungkook; Kimura, Hiroyuki; Watanabe, Masashi; Dohi, Yuki

    2013-06-01

    A new single-crystal neutron diffractometer based on a large-area curved two-dimensional position-sensitive detector (C-2DPSD) has been developed. The diffractometer commissioning is almost complete, together with development of the measurement methodology and the raw data processing software package, the Reciprocal Analyzer, and the instrument is now ready to be launched for users. Position decoding of the C-2DPSD is via a delay-line readout method with an effective angular range of 110 × 54° in the horizontal and vertical directions, respectively, with a nominal radius of curvature of 530 mm. The diffractometer is equipped with a Ge(311) mosaic monochromator and two supermirror vacuum guide paths, one before and one after the monochromator position. The commissioning incorporates corrections and calibration of the instrument using an NaCl crystal, various applications such as crystallographic and magnetic structure measurements, a crystallinity check on large crystals, and a study on the composition or dopant content of a mixed crystal of (Tm x Yb1-x )Mn2O5. The installation of the diffractometer and the measurement method, the calibration procedure and results, the raw data treatment and visualization, and several applications using the large C-2DPSD-based diffractometer are reported. PMID:23682194

  19. The Development and Application of a Method to Quantify the Quality of Cryoprotectant Conditions Using Standard Area Detector X-Ray Images

    NASA Technical Reports Server (NTRS)

    McFerrin, Michael; Snell, Edward; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    An X-ray based method for determining cryoprotectant concentrations necessary to protect solutions from crystalline ice formation was developed. X-ray images from a CCD area detector were integrated as powder patterns and quantified by determining the standard deviation of the slope of the normalized intensity curve in the resolution range where ice rings are known to occur. The method was tested determining the concentrations of glycerol, PEG400, ethylene glycol and 1,2-propanediol necessary to form an amorphous glass at 1OOK with each of the 98 crystallization solutions of Crystal Screens I and II (Hampton Research, Laguna Hills, California, USA). For conditions that required glycerol concentrations of 35% or above cryoprotectant conditions using 2,3-butanediol were determined. The method proved to be remarkably accurate. The results build on the work of [Garman and Mitchell] and extend the number, of suitable starting conditions to alternative cryoprotectants. In particular, 1,2-propanediol has emerged as a particularly good additive for glass formation upon flash cooling.

  20. Development and applications of a new neutron single-crystal diffractometer based on a two-dimensional large-area curved position-sensitive detector

    PubMed Central

    Lee, Chang-Hee; Noda, Yukio; Ishikawa, Yoshihisa; Kim, Shin Ae; Moon, Myungkook; Kimura, Hiroyuki; Watanabe, Masashi; Dohi, Yuki

    2013-01-01

    A new single-crystal neutron diffractometer based on a large-area curved two-dimensional position-sensitive detector (C-2DPSD) has been developed. The diffractometer commissioning is almost complete, together with development of the measurement methodology and the raw data processing software package, the Reciprocal Analyzer, and the instrument is now ready to be launched for users. Position decoding of the C-2DPSD is via a delay-line readout method with an effective angular range of 110 × 54° in the horizontal and vertical directions, respectively, with a nominal radius of curvature of 530 mm. The diffractometer is equipped with a Ge(311) mosaic monochromator and two supermirror vacuum guide paths, one before and one after the monochromator position. The commissioning incorporates corrections and calibration of the instrument using an NaCl crystal, various applications such as crystallographic and magnetic structure measurements, a crystallinity check on large crystals, and a study on the composition or dopant content of a mixed crystal of (TmxYb1−x)Mn2O5. The installation of the diffractometer and the measurement method, the calibration procedure and results, the raw data treatment and visualization, and several applications using the large C-2DPSD-based diffractometer are reported. PMID:23682194

  1. Sensitive detection of active Shiga toxin using low cost CCD based optical detector

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To reduce the sources and incidence of food-borne illness there is a need to develop inexpensive sensitive devices for detection of active toxin, such as Shiga toxin type 2 (Stx2). This approach increases the availability of foodborne bacterial toxin diagnostics in regions where there are limited r...

  2. 78 FR 35612 - Agency Information Collection Activities; Comment Request; Targeted Teacher Shortage Areas...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-13

    ... collection of information from Chief State School Officers to support and document the request for teacher... Agency Information Collection Activities; Comment Request; Targeted Teacher Shortage Areas Nationwide... to this notice will be considered public records. Title of Collection: Targeted Teacher...

  3. Particle Detectors

    NASA Astrophysics Data System (ADS)

    Grupen, Claus; Shwartz, Boris

    2011-09-01

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

  4. Thin detectors for the CHICSi {delta}E-E telescope

    SciTech Connect

    Evensen, L.; Westgaard, T.

    1996-12-31

    A pilot series of 10 {mu}m to 15 {mu}m thin silicon detectors has been made for the AE-E telescopes in the CHICSi experiment at the Celsius Heavy Ion Collider in Uppsala, Sweden. AE-E telescopes provide ion type identification and energy determination of collision fragments. The thin detectors are made as p-i-n diodes in thin etched membranes on 280 {mu}m thick silicon wafers. The membranes are made with anisotropic etching using 25 w% tetramethylammonium hydroxide (TMAH) solution. The etch speed of this solution is very uniform across a wafer. As a result detectors with uniform thickness can be produced. The etch depth varies with less than 0.3 {mu}m and the surface roughness is in the 2 - 4 nm range. Each detector has a 10.0 x 10.0 mm{sup 2} active area on a 10.2 x 10.2 mm{sup 2} membrane surrounded by a 1.1 mm wide supporting frame. The detectors have active area leakage currents of approximately 0.5 nA at 20 V. The breakdown voltage of the detectors is above 100 V. Test experiments with telescopes consisting of a thin detector in combination with a thick detector have shown excellent ion separation capabilities. Isotope separation of the isotope {sup 7}Be and the isotopes {sup 9}Be and {sup 10}Be can be seen.

  5. Quantitative radiography enabled by slot collimation and a novel scatter correction technique on a large-area flat panel x-ray detector

    NASA Astrophysics Data System (ADS)

    Yue, Meghan L.; Boden, Adam E.; Sabol, John M.

    2009-02-01

    In addition to causing loss of contrast and blurring in an image, scatter also makes quantitative measurements of xray attenuation impossible. Many devices, methods, and models have been developed to eliminate, estimate, and correct for the effects of scatter. Although these techniques can reduce the impact of scatter in a large-area image, no methods have proven to be practical and sufficient to enable quantitative analysis of image data in a routine clinical setting. This paper describes a method of scatter correction which uses moderate x-ray collimation in combination with a correction algorithm operating on data obtained from large-area flat panel detector images. The method involves acquiring slot collimated images of the object, and utilizing information from outside of the collimated region, in addition to a priori data, to estimate the scatter within the collimated region. This method requires no increase dose to the patient while providing high image quality and accurate estimates of the primary x-ray data. This scatter correction technique was validated through beam stop experiments and comparison of theoretically calculated and measured contrast of thin aluminum and polymethylmethacrelate objects. Measurements taken with various background material thicknesses, both with and without a grid, showed that the slot-scatter corrected contrast and the theoretical contrast were not significantly different given a 99% confidence interval. However, the uncorrected contrast was found to be significantly different from the corrected and theoretical contrasts. These findings indicate that this method of scatter correction can eliminate the effect of scatter on contrast and potentially enable quantitative x-ray imaging.

  6. 32 CFR Appendix C to Part 552 - Authorized Activities for Fort Lewis Maneuver Area Access

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Area Access C Appendix C to Part 552 National Defense Department of Defense (Continued) DEPARTMENT OF.... 552, App. C Appendix C to Part 552—Authorized Activities for Fort Lewis Maneuver Area Access Military...) Installation service and maintenance (AR 420-74, FL Reg 350-30) Non-DOD personnel in transit on...

  7. 32 CFR Appendix D to Subpart M of... - Unauthorized Activities in Maneuver Training Areas

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Areas D Appendix D to Subpart M of Part 552 National Defense Department of Defense (Continued.... D Appendix D to Subpart M of Part 552—Unauthorized Activities in Maneuver Training Areas 1. Fort... camping outside of DPCA sites (camping on DPCA sites is open to DoD members only, per above)....

  8. 32 CFR Appendix D to Subpart M of... - Unauthorized Activities in Maneuver Training Areas

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Areas D Appendix D to Subpart M of Part 552 National Defense Department of Defense (Continued.... D Appendix D to Subpart M of Part 552—Unauthorized Activities in Maneuver Training Areas 1. Fort... camping outside of DPCA sites (camping on DPCA sites is open to DoD members only, per above)....

  9. 32 CFR Appendix D to Part 552 - Unauthorized Activities in Fort Lewis Maneuver Areas

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Areas D Appendix D to Part 552 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY MILITARY RESERVATIONS AND NATIONAL CEMETERIES REGULATIONS AFFECTING MILITARY RESERVATIONS Pt. 552, App. D Appendix D to Part 552—Unauthorized Activities in Fort Lewis Maneuver Areas Civilian...

  10. 32 CFR Appendix D to Part 552 - Unauthorized Activities in Fort Lewis Maneuver Areas

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Areas D Appendix D to Part 552 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY MILITARY RESERVATIONS AND NATIONAL CEMETERIES REGULATIONS AFFECTING MILITARY RESERVATIONS Pt. 552, App. D Appendix D to Part 552—Unauthorized Activities in Fort Lewis Maneuver Areas Civilian...

  11. 32 CFR Appendix D to Part 552 - Unauthorized Activities in Fort Lewis Maneuver Areas

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Areas D Appendix D to Part 552 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY MILITARY RESERVATIONS AND NATIONAL CEMETERIES REGULATIONS AFFECTING MILITARY RESERVATIONS Pt. 552, App. D Appendix D to Part 552—Unauthorized Activities in Fort Lewis Maneuver Areas Civilian...

  12. 32 CFR Appendix D to Subpart M of... - Unauthorized Activities in Maneuver Training Areas

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Areas D Appendix D to Subpart M of Part 552 National Defense Department of Defense (Continued.... D Appendix D to Subpart M of Part 552—Unauthorized Activities in Maneuver Training Areas 1. Fort... camping outside of DPCA sites (camping on DPCA sites is open to DoD members only, per above)....

  13. 32 CFR Appendix D to Part 552 - Unauthorized Activities in Fort Lewis Maneuver Areas

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Areas D Appendix D to Part 552 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY MILITARY RESERVATIONS AND NATIONAL CEMETERIES REGULATIONS AFFECTING MILITARY RESERVATIONS Pt. 552, App. D Appendix D to Part 552—Unauthorized Activities in Fort Lewis Maneuver Areas Civilian...

  14. 32 CFR Appendix D to Part 552 - Unauthorized Activities in Fort Lewis Maneuver Areas

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Areas D Appendix D to Part 552 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY MILITARY RESERVATIONS AND NATIONAL CEMETERIES REGULATIONS AFFECTING MILITARY RESERVATIONS Pt. 552, App. D Appendix D to Part 552—Unauthorized Activities in Fort Lewis Maneuver Areas Civilian...

  15. 32 CFR Appendix D to Subpart M of... - Unauthorized Activities in Maneuver Training Areas

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Areas D Appendix D to Subpart M of Part 552 National Defense Department of Defense (Continued.... D Appendix D to Subpart M of Part 552—Unauthorized Activities in Maneuver Training Areas 1. Fort... camping outside of DPCA sites (camping on DPCA sites is open to DoD members only, per above)....

  16. 32 CFR Appendix D to Subpart M of... - Unauthorized Activities in Maneuver Training Areas

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Areas D Appendix D to Subpart M of Part 552 National Defense Department of Defense (Continued.... D Appendix D to Subpart M of Part 552—Unauthorized Activities in Maneuver Training Areas 1. Fort... camping outside of DPCA sites (camping on DPCA sites is open to DoD members only, per above)....

  17. Active wavelength selection for mixture identification with tunable mid-infrared detectors.

    PubMed

    Huang, Jin; Gutierrez-Osuna, Ricardo

    2016-09-21

    This article presents a wavelength selection framework for mixture identification problems. In contrast with multivariate calibration, where the mixture constituents are known and the goal is to estimate their concentration, in mixture identification the goal is to determine which of a large number of chemicals is present. Due to the combinatorial nature of this problem, traditional wavelength selection algorithms are unsuitable because the optimal set of wavelengths is mixture dependent. To address this issue, our framework interleaves wavelength selection with the sensing process, such that each subsequent wavelength is determined on-the-fly based on previous measurements. To avoid early convergence, our approach starts with an exploratory criterion that samples the spectrum broadly, then switches to an exploitative criterion that selects increasingly more relevant wavelengths as the solution approaches the true constituents of the mixture. We compare this "active" wavelength selection algorithm against a state-of-the-art passive algorithm (successive projection algorithm), both experimentally using a tunable spectrometer and in simulation using a large spectral library of chemicals. Our results show that our active method can converge to the true solution more frequently and with fewer measurements than the passive algorithm. The active method also leads to more compact solutions with fewer false positives. PMID:27590540

  18. History of infrared detectors

    NASA Astrophysics Data System (ADS)

    Rogalski, A.

    2012-09-01

    This paper overviews the history of infrared detector materials starting with Herschel's experiment with thermometer on February 11th, 1800. Infrared detectors are in general used to detect, image, and measure patterns of the thermal heat radiation which all objects emit. At the beginning, their development was connected with thermal detectors, such as thermocouples and bolometers, which are still used today and which are generally sensitive to all infrared wavelengths and operate at room temperature. The second kind of detectors, called the photon detectors, was mainly developed during the 20th Century to improve sensitivity and response time. These detectors have been extensively developed since the 1940's. Lead sulphide (PbS) was the first practical IR detector with sensitivity to infrared wavelengths up to ˜3 μm. After World War II infrared detector technology development was and continues to be primarily driven by military applications. Discovery of variable band gap HgCdTe ternary alloy by Lawson and co-workers in 1959 opened a new area in IR detector technology and has provided an unprecedented degree of freedom in infrared detector design. Many of these advances were transferred to IR astronomy from Departments of Defence research. Later on civilian applications of infrared technology are frequently called "dual-use technology applications." One should point out the growing utilisation of IR technologies in the civilian sphere based on the use of new materials and technologies, as well as the noticeable price decrease in these high cost technologies. In the last four decades different types of detectors are combined with electronic readouts to make detector focal plane arrays (FPAs). Development in FPA technology has revolutionized infrared imaging. Progress in integrated circuit design and fabrication techniques has resulted in continued rapid growth in the size and performance of these solid state arrays.

  19. A Wireless Object Location Detector Enabling People with Developmental Disabilities to Control Environmental Stimulation through Simple Occupational Activities with Nintendo Wii Balance Boards

    ERIC Educational Resources Information Center

    Shih, Ching-Hsiang; Chang, Man-Ling

    2012-01-01

    The latest researches have adopted software technology, turning the Nintendo Wii Balance Board into a high performance standing location detector with a newly developed standing location detection program (SLDP). This study extended SLDP functionality to assess whether two people with developmental disabilities would be able to actively perform…

  20. High sensitivity detectors for measurement of diffusion, emanation and low activity of radon

    SciTech Connect

    Mamedov, Fadahat; Štekl, Ivan; Smolek, Karel; Čermák, Pavel

    2013-08-08

    Today's underground experiments require ultra-low background conditions. One of the most important source of background is radon. It is necessary to suppress it and consequently to detect very low radon concentration. In the frame of SuperNEMO collaboration experimental setups for measurement of low radon activity, radon diffusion through shielding foils and radon emanation from construction materials have been constructed in IEAP CTU in Prague and the obtained results are presented. The application of Timepix device in radon detection is briefly discussed.

  1. Innovative high pressure gas MEM's based neutron detector for ICF and active SNM detection.

    SciTech Connect

    Martin, Shawn Bryan; Derzon, Mark Steven; Renzi, Ronald F.; Chandler, Gordon Andrew

    2007-12-01

    An innovative helium3 high pressure gas detection system, made possible by utilizing Sandia's expertise in Micro-electrical Mechanical fluidic systems, is proposed which appears to have many beneficial performance characteristics with regards to making these neutron measurements in the high bremsstrahlung and electrical noise environments found in High Energy Density Physics experiments and especially on the very high noise environment generated on the fast pulsed power experiments performed here at Sandia. This same system may dramatically improve active WMD and contraband detection as well when employed with ultrafast (10-50 ns) pulsed neutron sources.

  2. RADIATION DETECTOR

    DOEpatents

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

    1960-05-10

    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.

  3. Natural Environments, Obesity, and Physical Activity in Nonmetropolitan Areas of the United States

    ERIC Educational Resources Information Center

    Michimi, Akihiko; Wimberly, Michael C.

    2012-01-01

    Purpose: To assess the associations of the natural environment with obesity and physical activity in nonmetropolitan areas of the United States among representative samples by using 2 indices of outdoor activity potential (OAP) at the county level. Methods: We used the data from 457,820 and 473,296 noninstitutionalized adults aged over 18 years…

  4. Black-footed ferret areas of activity during late summer and fall at Meeteetse, Wyoming

    USGS Publications Warehouse

    Fagerstone, K.A.; Biggins, D.E.

    2011-01-01

    Radiotelemetry was used during 1983 and 1984 to collect information on short-term areas of activity for black-footed ferrets (Mustela nigripes) near Meeteetse, Wyoming. This population ultimately provided ferrets for the captive-breeding program that bred and released offspring into the wild since 1991. We fitted 5 adult ferrets and 13 juveniles with radiotransmitters and followed their movements during late summer and fall. Adult males had 7-day areas of activity that were >6 times as large as those of adult females. Activity areas of adult males varied little in coverage or location on a weekly basis, but females sequentially shifted their areas. Unlike juvenile females, juvenile males tended to leave their natal colonies. ?? 2011 American Society of Mammalogists.

  5. Overview of the Tank Focus Area HLW Tank Retrieval Activities (Remote Operations)

    SciTech Connect

    GIBBONS, P.W.

    2001-01-01

    Several U.S. Department of Energy (DOE) sites are currently retrieving or preparing to retrieve radioactive waste from underground storage tanks with technical assistance from the Tanks Focus Area. The Tanks Focus Area is a national program that provides information and technologies to safely and effectively remediate radioactive waste stored in DOE's underground tanks. Funding for the Tanks Focus Area is provided by the DOE Offices of Science and Technology, Environmental Restoration, and Waste Management. This paper provides an overview of recent remote waste retrieval activities as well as recent successes sponsored by the Tanks Focus Area.

  6. Quantitative analysis of an enlarged area Solid State X-ray Image Intensifier (SSXII) detector based on Electron Multiplying Charge Coupled Device (EMCCD) technology

    PubMed Central

    Swetadri, Vasan S.N.; Sharma, P.; Singh, V.; Jain, A.; Ionita, Ciprian N.; Titus, A.H.; Cartwright, A.N.; Bednarek, D.R; Rudin, S.

    2013-01-01

    Present day treatment for neurovascular pathological conditions involves the use of devices with very small features such as stents, coils, and balloons; hence, these interventional procedures demand high resolution x-ray imaging under fluoroscopic conditions to provide the capability to guide the deployment of these fine endovascular devices. To address this issue, a high resolution x-ray detector based on EMCCD technology is being developed. The EMCCD field-of-view is enlarged using a fiber-optic taper so that the detector features an effective pixel size of 37 µm giving it a Nyquist frequency of 13.5 lp/mm, which is significantly higher than that of the state of the art Flat Panel Detectors (FPD). Quantitative analysis of the detector, including gain calibration, instrumentation noise equivalent exposure (INEE) and modulation transfer function (MTF) determination, are presented in this work. The gain of the detector is a function of the detector temperature; with the detector cooled to 5° C, the highest relative gain that could be achieved was calculated to be 116 times. At this gain setting, the lowest INEE was measured to be 0.6 µR/frame. The MTF, measured using the edge method, was over 2% up to 7 cycles/ mm. To evaluate the performance of the detector under clinical conditions, an aneurysm model was placed over an anthropomorphic head phantom and a coil was guided into the aneurysm under fluoroscopic guidance using the detector. Image sequences from the procedure are presented demonstrating the high resolution of this SSXII. PMID:24353386

  7. CERN-RD39 collaboration activities aimed at cryogenic silicon detector application in high-luminosity Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Li, Zheng; Eremin, Vladimir; Verbitskaya, Elena; Dehning, Bernd; Sapinski, Mariusz; Bartosik, Marcin R.; Alexopoulos, Andreas; Kurfürst, Christoph; Härkönen, Jaakko

    2016-07-01

    Beam Loss Monitors (BLM) made of silicon are new devices for monitoring of radiation environment in the vicinity of superconductive magnets of the Large Hadron Collider. The challenge of BLMs is extreme radiation hardness, up to 1016 protons/cm2 while placed in superfluid helium (temperature of 1.9 K). CERN BE-BI-BL group, together with CERN-RD39 collaboration, has developed prototypes of BLMs and investigated their device physics. An overview of this development-results of the in situ radiation tests of planar silicon detectors at 1.9 K, performed in 2012 and 2014-is presented. Our main finding is that silicon detectors survive under irradiation to 1×1016 p/cm2 at 1.9 K. In order to improve charge collection, current injection into the detector sensitive region (Current Injection Detector (CID)) was tested. The results indicate that the detector signal increases while operated in CID mode.

  8. Drainage basin morphometry controls on the active depositional area of debris flow fans

    NASA Astrophysics Data System (ADS)

    Mihir, Monika; Wasklewicz, Thad; Malamud, Bruce

    2015-04-01

    A majority of the research on understanding the connection between alluvial fans and drainage basins to date has focused on coarse-scale relations between total fan area and drainage basin area. Here we take a new approach where we assess relationships between active fan depositional area and drainage basin morphometry using 52 debris flow fans (32 from the White Mountains and 20 from the Inyo Mountains) on the eastern side of Owens Valley, California, USA. The boundaries for fans, drainage basin and active depositional areas were delineated from 10m digital elevation models and 1 m aerial photographs. We examined the relationships between the normalised active depositional area of the fan (Afad/Af, where Afad is the fan active depositional area and Af the entire fan area) and the following four variables for drainage basin: (i) area (Adb), (ii) total stream length (Ls), (iii) relief (BHH), (iv) roughness (R). We find a statistically significant (r2 > 0.40) inverse power-law relationship between recent sediment contribution to the fan and drainage basin area (Afad/Af = 0.29Adb-0.167) drainage network length (Afad/Af = 0.39Ls-0.161) and basin relief (Afad/Af = 3.90BHH-0.401), and a statistically weak (r2 = 0.22) inverse power law with basin roughness (Afad/Af = 0.32R0.5441). Drainage basin size combined with other morphometric variables may largely determine efficiency in sediment transport and delivery to the fan surface. A large proportion of the total fan area of smaller fans are flooded by debris flow indicating less sediment storage in the drainage basins and greater efficiency in sediment delivery. The findings signify the importance of coarse-scale relationships to both long- and short-term fan evolution.

  9. Cross Section Measurements Using the Zero Degree Detector

    NASA Technical Reports Server (NTRS)

    Christl, M. J.; Adams, J. H., Jr.; Heilbronn, L.; Kuznetsov, E. N.; Miller, J.; Zeitlin, C.

    2007-01-01

    The Zero Degree Detector (ZDD) is an instrument that has been used in accelerator exposures to measure the angular dependence of particles produced in heavy ion fragmentation experiments. The ZDD uses two identical layers of pixelated silicon detectors that make coincident measurements over the active area of the instrument. The angular distribution of secondary particle produced in nuclear interactions for several heavy ions: and target materials will be presented along with performance characteristic of the instrument.

  10. P-Them Response for Geologically Active and Non-Active Areas

    NASA Astrophysics Data System (ADS)

    Vetrov, A.

    2011-12-01

    Time Domain Electromagnetic air-borne systems are widely used in geological exploration for minerals associated with conductive rocks, underground water resources and geological underground mapping. The newly designed P-THEM system has been test-flown at the Reid Mahaffy geological test site in Northern Ontario, Canada; and then over an area near Newmarket, north of Toronto. While the flight in Reid Mahaffy was made to verify real characteristics of the system: stability and repeatability of results, the flight over the Newmarket area was made to verify correct operation of the EM system with a magnetometer and gamma-ray spectrometer. Interesting and significant response of the TDEM observations to geological, agricultural and engineering objects were observed during the test flights. These results demonstrate a possibility of TDEM method for mineral research and environmental tasks. The Reid Mahaffy Test Site is located in the Abitibi Subprovince, immediately east of the Mattagami River Fault in Ontario, Canada. The test site was created in 1999 by the Ontario Geological Survey, initially to enable various airborne geophysical systems to demonstrate their basic performance capabilities. The general geology of the site contains known overburden thickness based on almost 50 diamond drill holes, with geological logs available for these. The survey flights over Reid Mahaffy test site were performed in April 2010. The altitude and direction tests were flown on three lines over the test survey area. The response of early times represents overburden and correlates with its known thickness. The conductive body appears on later time channels and remains detectable over noise level. The electrical inversion of the results allows distinguishing a structure of several vertical conductor slices, forming the conductive body. The Newmarket area selected for tests in June 2010 is a highly developed urban zone in the Greater Toronto Area, Ontario, Canada. Geologically, the area is

  11. Areas of activity in biofilms through the biospeckle and the spectral domain

    NASA Astrophysics Data System (ADS)

    Marques, J. K.; Braga, R. A.; Pereira, J.

    2010-09-01

    The dynamic laser speckle or biospeckle laser has been used to analyze the activity of biological and non-biological material by means of various statistical techniques and image processing. However, a challenge to adopt this technique is the ability to identify, in the same material, an area of low activity immersed in an environment of a higher activity. This work was carried out to evaluate the spectral approach associated to biospeckle laser technique as an alternative to identify distinct activities areas in the same material. Biofilm samples, which present well known protocols to be prepared, and a simpler structure than vegetal and animal tissues, were prepared with potato starch and corn starch with areas of different levels of moisture and were analyzed using the biospeckle laser associated with the wavelets transform in order to evaluate the data in the spectral domain. The effect of a black or white background below the samples was also tested. The image analysis was conducted using Generalized Difference and Fujii techniques before and after the implementation of the wavelets transform producing the filtration of the data. The results allowed the visualization of different activities areas in different frequency bands. The areas of activity were presented clearer than the traditional procedures without filtering. A new way to present the results of the biospeckle and the frequency domain information was proposed to enhance the visualization of a whole picture. It was also noted that the greatest contrast between areas of different activity were promoted by materials of different compositions. In some experimental configurations there were possible to tag the relationship between the frequency and depth of the active or inactive material. The influence of the color, black or white, of the background was also noticed in the results, but with white background better in some configurations and with the black better in others.

  12. Neutron detector simultaneously measures fluence and dose equivalent

    NASA Technical Reports Server (NTRS)

    Dvorak, R. F.; Dyer, N. C.

    1967-01-01

    Neutron detector acts as both an area monitoring instrument and a criticality dosimeter by simultaneously measuring dose equivalent and fluence. The fluence is determined by activation of six foils one inch below the surface of the moderator. Dose equivalent is determined from activation of three interlocked foils at the center of the moderator.

  13. VEGA: A low-power front-end ASIC for large area multi-linear X-ray silicon drift detectors: Design and experimental characterization

    NASA Astrophysics Data System (ADS)

    Ahangarianabhari, Mahdi; Macera, Daniele; Bertuccio, Giuseppe; Malcovati, Piero; Grassi, Marco

    2015-01-01

    We present the design and the first experimental characterization of VEGA, an Application Specific Integrated Circuit (ASIC) designed to read out large area monolithic linear Silicon Drift Detectors (SDD's). VEGA consists of an analog and a digital/mixed-signal section to accomplish all the functionalities and specifications required for high resolution X-ray spectroscopy in the energy range between 500 eV and 50 keV. The analog section includes a charge sensitive preamplifier, a shaper with 3-bit digitally selectable shaping times from 1.6 μs to 6.6 μs and a peak stretcher/sample-and-hold stage. The digital/mixed-signal section includes an amplitude discriminator with coarse and fine threshold level setting, a peak discriminator and a logic circuit to fulfill pile-up rejection, signal sampling, trigger generation, channel reset and the preamplifier and discriminators disabling functionalities. A Serial Peripherical Interface (SPI) is integrated in VEGA for loading and storing all configuration parameters in an internal register within few microseconds. The VEGA ASIC has been designed and manufactured in 0.35 μm CMOS mixed-signal technology in single and 32 channel versions with dimensions of 200 μm×500 μm per channel. A minimum intrinsic Equivalent Noise Charge (ENC) of 12 electrons r.m.s. at 3.6 μs peaking time and room temperature is measured and the linearity error is between -0.9% and +0.6% in the whole input energy range. The total power consumption is 481 μW and 420 μW per channel for the single and 32 channels version, respectively. A comparison with other ASICs for X-ray SDD's shows that VEGA has a suitable low noise and offers high functionality as ADC-ready signal processing but at a power consumption that is a factor of four lower than other similar existing ASICs.

  14. Odours stimulate neuronal activity in the dorsolateral area of the hippocampal formation during path integration

    PubMed Central

    Jorge, P. E.; Phillips, J. B.; Gonçalves, A.; Marques, P. A. M.; Nĕmec, P.

    2014-01-01

    The dorsolateral area of the hippocampal formation of birds is commonly assumed to play a central role in processing information needed for geographical positioning and homing. Previous work has interpreted odour-induced activity in this region as evidence for an ‘olfactory map’. Here, we show, using c-Fos expression as a marker, that neuronal activation in the dorsolateral area of the hippocampal formation of pigeons is primarily a response to odour novelty, not to the spatial distribution of odour sources that would be necessary for an olfactory map. Pigeons exposed to odours had significantly more neurons activated in this area of the brain than pigeons exposed to filtered air with odours removed. This increased activity was observed only in response to unfamiliar odours. No change in activity was observed when pigeons were exposed to home odours. These findings are consistent with non-home odours activating non-olfactory components of the pigeon's navigation system. The pattern of neuronal activation in the triangular and dorsomedial areas of the hippocampal formation was, by contrast, consistent with the possibility that odours play a role in providing spatial information. PMID:24671977

  15. Large area neutron detector based on Li6 ionization chamber with integrated body-moderator of high density polyethylene

    SciTech Connect

    Ianakiev, Kiril D.; Swinhoe, Martyn T.; Chung, Kiwhan; Makela, Mark F.

    2009-06-30

    A detector was developed and funded by DHS to be a lower cost alternative to 3He detectors. A 6Li foil-lined ionization chamber was prepared with fill gas at one atmosphere and pulse mode operation. The high-density polyethylene (HOPE) body serves also as a neutron moderator. All electrodes, including high voltage bias supply, are hermetically sealed within the plastic slabs.

  16. Coarse-scaling adjustment of fine-group neutron spectra for epithermal neutron beams in BNCT using multiple activation detectors

    NASA Astrophysics Data System (ADS)

    Liu, Yuan-Hao; Nievaart, Sander; Tsai, Pi-En; Liu, Hong-Ming; Moss, Ray; Jiang, Shiang-Huei

    2009-01-01

    In order to provide an improved and reliable neutron source description for treatment planning in boron neutron capture therapy (BNCT), a spectrum adjustment procedure named coarse-scaling adjustment has been developed and applied to the neutron spectrum measurements of both the Tsing Hua Open-pool Reactor (THOR) epithermal neutron beam in Taiwan and the High Flux Reactor (HFR) in The Netherlands, using multiple activation detectors. The coarse-scaling adjustment utilizes a similar idea as the well-known two-foil method, which adjusts the thermal and epithermal neutron fluxes according to the Maxwellian distribution for thermal neutrons and 1/ E distribution over the epithermal neutron energy region. The coarse-scaling adjustment can effectively suppress the number of oscillations appearing in the adjusted spectrum and provide better smoothness. This paper also presents a sophisticated 9-step process utilizing twice the coarse-scaling adjustment which can adjust a given coarse-group spectrum into a fine-group structure, i.e. 640 groups, with satisfactory continuity and excellently matched reaction rates between measurements and calculation. The spectrum adjustment algorithm applied in this study is the same as the well-known SAND-II.

  17. Growth and activation of group IV semiconductors for application in infrared detectors and photovoltaics

    NASA Astrophysics Data System (ADS)

    Xie, Junqi

    Bandgaps in group IV semiconductors such as Ge1-ySn y and Ge1-x-ySixSny are tunable by varying the material composition. The tunable bandgaps make these materials with potential applications in photodetectors, modulators, waveguiders, lasers and photovolatics. This dissertation reports significant improvements of the low-temperature chemical vapor deposition (CVD) process leading to growth of device quality Ge0.98Sn0.02 films with thickness over 500 nm. Highly controlled and efficient doping protocols were also developed to obtain facile substitution and complete activation of dopant atoms at levels 1017 -- 1019 cm-3 via both conventional and custom built molecules. Ge0.98Sn0.02-based PIN structures were subsequently fabricated and characterized. Results show that the incorporation of only 2% of Sn extends the infrared performance of Ge0.98Sn 0.02 based optoelectronic devices to the entire range of transmission windows for telecom applications. Higher Sn content (5% Sn) Ge1-ySny films were also studied to extend the device performance range even further into the infrared. The successful depositions of intrinsic, p- and n-type materials with doping levels 1018-1020/cm3 indicate all components were in place for the fabrication of Ge0.95Sn 0.02-based PIN structures. Meanwhile, a new approach to high quality Ge1-x-ySix Sny ternaries grown directly on both Ge(100) and Si (100) substrates was established based on commercially available sources such as trisilane, digermane and stannane. The soft chemistry process was extended to fabricated p- and n-type layers on Si, and their optical and electrical properties were determined. Characterizations indicate that the properties of GeSiSn are independent of the platform on which they are grown including Si, Ge or GeSn/Si. First-principles calculations show that mixing entropy thermodynamically stabilizes SiGeSn in contrast to GeSn analogs with the same Sn content, in good agreement with experimentally observation. In addition

  18. Sustained attention to spontaneous thumb sensations activates brain somatosensory and other proprioceptive areas.

    PubMed

    Bauer, Clemens C C; Díaz, José-Luis; Concha, Luis; Barrios, Fernando A

    2014-06-01

    The present experiment was designed to test if sustained attention directed to the spontaneous sensations of the right or left thumb in the absence of any external stimuli is able to activate corresponding somatosensory brain areas. After verifying in 34 healthy volunteers that external touch stimuli to either thumb effectively activate brain contralateral somatosensory areas, and after subtracting attention mechanisms employed in both touch and spontaneous-sensation conditions, fMRI evidence was obtained that the primary somatosensory cortex (specifically left BA 3a/3b) becomes active when an individual is required to attend to the spontaneous sensations of either thumb in the absence of external stimuli. In addition, the left superior parietal cortex, anterior cingulate gyrus, insula, motor and premotor cortex, left dorsolateral prefrontal cortex, Broca's area, and occipital cortices were activated. Moreover, attention to spontaneous-sensations revealed an increased connectivity between BA 3a/3b, superior frontal gyrus (BA 9) and anterior cingulate cortex (BA 32), probably allowing top-down activations of primary somatosensory cortex. We conclude that specific primary somatosensory areas in conjunction with other left parieto-frontal areas are involved in processing proprioceptive and interoceptive bodily information that underlies own body-representations and that these networks and cognitive functions can be modulated by top-down attentional processes. PMID:24727703

  19. Decoding Target Distance and Saccade Amplitude from Population Activity in the Macaque Lateral Intraparietal Area (LIP)

    PubMed Central

    Bremmer, Frank; Kaminiarz, Andre; Klingenhoefer, Steffen; Churan, Jan

    2016-01-01

    Primates perform saccadic eye movements in order to bring the image of an interesting target onto the fovea. Compared to stationary targets, saccades toward moving targets are computationally more demanding since the oculomotor system must use speed and direction information about the target as well as knowledge about its own processing latency to program an adequate, predictive saccade vector. In monkeys, different brain regions have been implicated in the control of voluntary saccades, among them the lateral intraparietal area (LIP). Here we asked, if activity in area LIP reflects the distance between fovea and saccade target, or the amplitude of an upcoming saccade, or both. We recorded single unit activity in area LIP of two macaque monkeys. First, we determined for each neuron its preferred saccade direction. Then, monkeys performed visually guided saccades along the preferred direction toward either stationary or moving targets in pseudo-randomized order. LIP population activity allowed to decode both, the distance between fovea and saccade target as well as the size of an upcoming saccade. Previous work has shown comparable results for saccade direction (Graf and Andersen, 2014a,b). Hence, LIP population activity allows to predict any two-dimensional saccade vector. Functional equivalents of macaque area LIP have been identified in humans. Accordingly, our results provide further support for the concept of activity from area LIP as neural basis for the control of an oculomotor brain-machine interface.

  20. MONDE: MOmentum Neutron DEtector

    NASA Astrophysics Data System (ADS)

    Santa Rita, P.; Acosta, L.; Favela, F.; Huerta, A.; Ortiz, M. E.; Policroniades, R.; Chávez, E.

    2016-07-01

    MONDE is a large area neutron momentum detector, consisting of a 70x160x5 cm3 plastic scintillator slab surrounded by 16 photomultiplier tubes, standard NIM signal processing electronics and a CAMAC data acquisition system. In this work we present data from a characterization run using an external trigger. For that purpose, coincident gamma rays from a 60Co radioactive source were used together with a NaI external detector. First results with an "external" trigger are presented.

  1. Improved gaseous leak detector

    DOEpatents

    Juravic, F.E. Jr.

    1983-10-06

    In a short path length mass-spectrometer type of helium leak detector wherein the helium trace gas is ionized, accelerated and deflected onto a particle counter, an arrangement is provided for converting the detector to neon leak detection. The magnetic field of the deflection system is lowered so as to bring the nonlinear fringe area of the magnetic field across the ion path, thereby increasing the amount of deflection of the heavier neon ions.

  2. Gaseous leak detector

    DOEpatents

    Juravic, Jr., Frank E.

    1988-01-01

    In a short path length mass-spectrometer type of helium leak detector wherein the helium trace gas is ionized, accelerated and deflected onto a particle counter, an arrangement is provided for converting the detector to neon leak detection. The magnetic field of the deflection system is lowered so as to bring the non linear fringe area of the magnetic field across the ion path, thereby increasing the amount of deflection of the heavier neon ions.

  3. A standing location detector enabling people with developmental disabilities to control environmental stimulation through simple physical activities with Nintendo Wii Balance Boards.

    PubMed

    Shih, Ching-Hsiang

    2011-01-01

    This study evaluated whether two people with developmental disabilities would be able to actively perform simple physical activities by controlling their favorite environmental stimulation using Nintendo Wii Balance Boards with a newly developed standing location detection program (SLDP, i.e., a new software program turning a Nintendo Wii Balance Board into a standing location detector). This study was carried out using to an ABAB design. The data showed that both participants significantly increased their simple physical activity (target response) to activate the control system to produce environmental stimulation during the B (intervention) phases. The practical and developmental implications of the findings are discussed. PMID:21159488

  4. Study of the timing performance of micro-channel plate photomultiplier for use as an active layer in a shower maximum detector

    NASA Astrophysics Data System (ADS)

    Ronzhin, A.; Los, S.; Ramberg, E.; Apresyan, A.; Xie, S.; Spiropulu, M.; Kim, H.

    2015-09-01

    We continue the study of micro-channel plate photomultiplier (MCP-PMT) as the active element of a shower maximum (SM) detector. We present test beam results obtained with Photek 240 and Photonis XP85011 MCP-PMTs devices. For proton beams, we obtained a time resolution of 9.6 ps, representing a significant improvement over past results using the same time of flight system. For electron beams, the time resolution obtained for this new type of SM detector is measured to be at the level of 13 ps when we use Photek 240 as the active element of the SM. Using the Photonis XP85011 MCP-PMT as the active element of the SM, we performed time resolution measurements with pixel readout, and achieved a TR better than 30 ps, The pixel readout was observed to improve upon the TR compared to the case where the individual channels were summed.

  5. Burned area, active fires and biomass burning - approaches to account for emissions from fires in Tanzania

    NASA Astrophysics Data System (ADS)

    Ruecker, Gernot; Hoffmann, Anja; Leimbach, David; Tiemann, Joachim; Ng'atigwa, Charles

    2013-04-01

    Eleven years of data from the globally available MODIS burned area and the MODS Active Fire Product have been analysed for Tanzania in conjunction with GIS data on land use and cover to provide a baseline for fire activity in this East African country. The total radiated energy (FRE) emitted by fires that were picked up by the burned area and active fire product is estimated based on a spatio-temporal clustering algorithm over the burned areas, and integration of the fire radiative power from the MODIS Active Fires product over the time of burning and the area of each burned area cluster. Resulting biomass combusted by unit area based on Woosteŕs scaling factor for FRE to biomass combusted is compared to values found in the literature, and to values found in the Global Fire Emissions Database (GFED). Pyrogenic emissions are then estimated using emission factors. According to our analysis, an average of 11 million ha burn annually (ranging between 8.5 and 12.9 million ha) in Tanzania corresponding to between 10 and 14 % of Tanzaniás land area. Most burned area is recorded in the months from May to October. The land cover types most affected are woodland and shrubland cover types: they comprise almost 70 % of Tanzania's average annual burned area or 6.8 million ha. Most burning occurs in gazetted land, with an annual average of 3.7 million ha in forest reserves, 3.3 million ha in game reserves and 1.46 million ha in national parks, totalling close to 8.5 million ha or 77 % of the annual average burned area of Tanzania. Annual variability of burned area is moderate for most of the analysed classes, and in most cases there is no clear trend to be detected in burned area, except for the Lindi region were annual burned area appears to be increasing. Preliminary results regarding emissions from fires show that for larger fires that burn over a longer time, biomass burned derived through the FRP method compares well to literature values, while the integration over

  6. The CMS Tracker Detector Control System

    NASA Astrophysics Data System (ADS)

    Yousaf Shah, S.; Tsirou, Andromachi; Verdini, Piero Giorgio; Hartmann, Frank; Masetti, Lorenzo; Dirkes, Guido H.; Stringer, Robert; Fahrer, Manuel

    2009-06-01

    The Compact Muon Solenoid DCS (CMS) Silicon Strip Tracker is by far the largest detector ever built in micro-strip technology. It has an active surface area of 198 m 2 consisting of 15,148 silicon modules with 9,316,352 readout channels read via 75,376 Analog Pipeline Voltage (APV) front-end chips and a total of 24,244 sensors. The Detector Control System (DCS) for the Tracker is a distributed control system that operates ˜2000 power supplies for the silicon modules and also monitors its environmental sensors. The DCS receives information from about 10 3 environmental probes (temperature and humidity sensors) located inside the detector's volume and values from these probes are driven through the Programmable Logic Controllers (PLC) of the Detector Safety System (DSS). A total of 10 5 parameters are read out from the dedicated chips in the front-end electronics of the detector via the data acquisition system, and a total of 10 5 parameters are read from the power supply modules. All these parameters are monitored, evaluated and correlated with the detector layout; actions are taken under specific conditions. The hardware for DCS consists of 10 PCs and 10 PLC systems that are continuously running the necessary control and safety routines. The DCS is a fundamental tool for the Tracker operation and its safety.

  7. Models of neural novelty detectors, with similarities to cerebral cortex.

    PubMed

    Salu, Y

    1988-01-01

    A novelty detector is a functional unit, that indicates whether an incoming stimulus is familiar or novel. Novelty detection is prevalent in the central nervous system (CNS), and is involved in various activities. Its basic characteristics are discussed first. Then, models of neural novelty detectors are described, and tested and evaluated in simulations. The simulations have shown that one novelty detector, the bi-compartmental, simulates very closely the behavior of neural novelty detectors. This model is constructed in a way that resembles the observed architecture and function of area 17, and similar regions in the cortex. The first step in novelty detection is data retrieval. The proposed novelty detectors can utilize various compatible modes of data storage and retrieval, and one of those has been utilized in the simulations. PMID:3355886

  8. [Preparation, characterization and adsorption performance of high surface area biomass-based activated carbons].

    PubMed

    Li, Kun-Quan; Li, Ye; Zheng, Zheng; Sang, Da-Zhi

    2013-01-01

    High surface area activated carbons were prepared with Spartina alterniflora and cotton stalk as raw materials and KOH as activating agent. Effects of materials type, impregnation ratio, activation temperature and heat preservation time on the yield, elemental composition and adsorptive capacity of activated carbon were studied. The properties and pore structure of the carbons were characterized with nitrogen adsorption, powder X-ray diffractometry (XRD), infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Main pore characteristics of activated carbons were analyzed by BET equation, Horvath-Kawazoe BET method and DFT method. The considerable preparation conditions are obtained as follows: impregnation ratio of 3: 1, an activation temperature of 800 degrees C and an activation time of 1.5 h. The BET surface area of activated carbon prepared from Spartina alterniflora reached 2 825 m2 x g(-1) when its total pore volume, yield, iodine number and methylene blue adsorption were 1.374 cm3 x g(-1), 16.36%, 1797 mg x g(-1) and 495 mg x g(-1) respectively under above conditions. The activated carbon from cotton stalk was prepared with BET surface area of 2 135 m2 x g(-1), total pore volume of 1.038 cm3 x g(-1), yield of 11.22%, methylene blue adsorption of 1 251 mg x g(-1), and iodine number of 478 mg x g(-1), respectively. The methylene blue adsorption and iodine number are much higher than the national first level for activated carbon. The Langmuir maximum adsorption capacities of 2,4-dinitrophenol on the two carbons were 932 mg x g(-1) and 747 mg x g(-1), respectively, which are superior to ordinary activated carbon and activated carbon fiber. PMID:23487959

  9. Voltage-sensitive dye imaging of primary motor cortex activity produced by ventral tegmental area stimulation.

    PubMed

    Kunori, Nobuo; Kajiwara, Riichi; Takashima, Ichiro

    2014-06-25

    The primary motor cortex (M1) receives dopaminergic projections from the ventral tegmental area (VTA) through the mesocortical dopamine pathway. However, few studies have focused on changes in M1 neuronal activity caused by VTA activation. To address this issue, we used voltage-sensitive dye imaging (VSD) to reveal the spatiotemporal dynamics of M1 activity induced by single-pulse stimulation of VTA in anesthetized rats. VSD imaging showed that brief electrical stimulation of unilateral VTA elicited a short-latency excitatory-inhibitory sequence of neuronal activity not only in the ipsilateral but also in the contralateral M1. The contralateral M1 response was not affected by pharmacological blockade of ipsilateral M1 activity, but it was completely abolished by corpus callosum transection. Although the VTA-evoked neuronal activity extended throughout the entire M1, we found the most prominent activity in the forelimb area of M1. The 6-OHDA-lesioned VTA failed to evoke M1 activity. Furthermore, both excitatory and inhibitory intact VTA-induced activity was entirely extinguished by blocking glutamate receptors in the target M1. When intracortical microstimulation of M1 was paired with VTA stimulation, the evoked forelimb muscle activity was facilitated or inhibited, depending on the interval between the two stimuli. These findings suggest that VTA neurons directly modulate the excitability of M1 neurons via fast glutamate signaling and, consequently, may control the last cortical stage of motor command processing. PMID:24966388

  10. Detectors on base of scintillation structures for registration of volumetric activities of gaseous and liquid media gamma radiation

    NASA Astrophysics Data System (ADS)

    Kadilin, V. V.; Yurov, V. N.; Ryabeva, E. V.; Samossadny, V. T.; Lupar, E. E.; Trofimov, Yu A.; Kolesnikov, S. V.; Chebishev, S. B.; Nebolsin, V. O.

    2016-02-01

    The main aim of this research is the development and prototyping of the ionizing radiation detectors for the diagnosis of the physical processes used for monitoring the radiation situation at the thermal or fast neutrons reactors. In this article we present the experimental verification of applicability of the scintillation detectors based on LaBr3(Ce) and YAlO3(Ce). The experimental studies of the gamma-ray detection with several designs of the crystal scintillation detectors in gas and liquid are considered. It was shown that the measurement range in the liquid medium at the duration of one measurement of 100 seconds for 137Cs equals from 3.79·102 Bq/l to 1.08·108 Bq/l for detector prototype based on YAlO3(Ce).

  11. [Effects of Different Reclaimed Scenarios on Soil Microbe and Enzyme Activities in Mining Areas].

    PubMed

    Li, Jun-jian; Liu, Feng; Zhou, Xiao-mei

    2015-05-01

    Abstract: Ecological degradation in the mining areas is greatly aggravated in recent several decades, and ecological restoration has become the primary measure for the sustainable development. Soil microbe and enzyme activity are sensitive indices to evaluate soil quality. Ecological reconstruction was initiated in Antaibao mining area, and we tested soil physicochemical properties, microbial populations of azotobacteria, nitrifying-bacteria and denitrifying-bacteria, and enzyme activities (including sucrose, polyphenol oxidase, dehydrogenase and urease) under different regeneration scenarios. Regeneration scenarios had significant effects on soil physicochemical properties, microbial population and enzyme activities. Total nitrogen was strongly correlated with azotobacteria and nitrifying-bacteria, however, total nitrogen was not correlated with denitrifying-bacteria. Phenol oxidase activity was negatively correlated with soil organic carbon and total nitrogen, but other enzyme activities were positively correlated with soil organic carbon and total nitrogen. Principal Component Analysis ( PCA) was applied to analyze the integrated fertility index (IFI). The highest and lowest IFIs were in Robinia pseudoacacia-Pinus tabuliformis mixed forests and un-reclaimed area, respectively. R. pseudoacacia-P. tabuliformis mixed forests were feasible for reclaimed mining areas in semi-arid region Northwest Shanxi. PMID:26314137

  12. Chacterization and application of a GE amorphous silicon flat panel detector in a synchrotron light source.

    SciTech Connect

    Lee, J. H.; Miceli, A.; Almer, J.; Bernier, J.; Chapman, K.; Chupas, P.; Haeffner, D.; Lee, P. L.; Lienert, U.; Aydiner, C.; Vera, G.; Kump, K.; LANL; GE Healthcare

    2007-01-01

    Characterization, in the language of synchrotron radiation, was performed on a GE Revolution 41RT flat panel detector using the X-ray light source at the Advanced Photon Source (APS). The detector has an active area of 41 x 41 cm{sup 2} with 200 x 200 {micro}m{sup 2} pixel size. The nominal working photon energy is around 80 keV. Modulation transfer function (MTF) was measured in terms of line spread function (LSF) using a 25 {micro}m x 1 cm tungsten slit. Memory effects of the detector elements, called lag, were also measured. The large area and fast data capturing rate - 8 fps in unbinned mode, 30 fps in binned or region of interest (ROI) mode - make the GE flat panel detector a unique and very versatile detector for synchrotron experiments. In particular, we present data from pair distribution function (PDF) measurements to demonstrate the special features of this detector.

  13. Smoke Detector

    NASA Technical Reports Server (NTRS)

    1979-01-01

    In the photo, Fire Chief Jay Stout of Safety Harbor, Florida, is explaining to young Richard Davis the workings of the Honeywell smoke and fire detector which probably saved Richard's life and that of his teen-age brother. Alerted by the detector's warning, the pair were able to escape their burning home. The detector in the Davis home was one of 1,500 installed in Safety Harbor residences in a cooperative program conducted by the city and Honeywell Inc.

  14. 480x384 element InSb detector with digital processor

    NASA Astrophysics Data System (ADS)

    Nesher, Ofer; Elkind, Shimon; Nevo, I.; Markovitz, Tuvy; Ganany, Ayelet; Marhashev, A. B.; Ben-Ezra, M.

    2004-08-01

    After completing the development of a digital detector with a format of 640x512 elements ("Sebastian"), SCD is now developing a mid format digital detector with 480x384 elements. This detector is based on the same concept as Sebastian, which was introduced last year at the SPIE conference in Orlando. The 480x384 element detector has all the features and performance of Sebastian as then introduced, and in addition exhibits some additional functionality. The format of the 480x384 element detector was chosen in order to maintain the same active area as in a standard format 320x256 element detector of today. Thus with specific system optics, a higher resolution is achieved with our new detector. As a direct consequence, the detection range is increased by 22-35% depending on the target type, when using this detector instead of the conventional 320x256 element detector in a typical system. The 480x384 element detector is designed to be integrated both into imaging systems and into head seekers missile-applications. In this paper we present the concept and the basic structure of the detector, the special operation modes unique to the digital detector, and the results of detection range calculations.

  15. High-pressure xenon detector development at Constellation Technology Corporation

    NASA Astrophysics Data System (ADS)

    Austin, Robert A.; Bastian, Lloyd F.

    2006-08-01

    Xenon-filled ionization detectors, due to their high atomic number fill gas (Z=54), moderate densities (~0.3 g/cm 3-0.5 g/cm 3) and good energy resolution (2%-4% at 662 keV), fill an important niche between more familiar technologies such as NaI(Tl) scintillators and Germanium detectors. Until recently, difficulties with obtaining sufficient Xenon purity, reducing microphonic sensitivity, and developing low-noise electronics compatible with small ionization signals have hampered the development of this nuclear detection field. Constellation Technology Corporation, whose experience with xenon detectors goes back to the mid 1990's, has made significant progress in these areas and has developed a commercial line of detectors with active volumes ranging from small (35 g Xe) to large (1400 g Xe). Here we will discuss our development of a mobile, large area, spectroscopic array.

  16. Public Parks in Hong Kong: Characteristics of Physical Activity Areas and Their Users

    PubMed Central

    Chow, Bik C.; McKenzie, Thomas L.; Sit, Cindy H. P.

    2016-01-01

    Public parks, salient locations for engaging populations in health promoting physical activity, are especially important in high-density cities. We used the System for Observing Physical Activity in Communities (SOPARC) to conduct the first-ever surveillance study of nine public parks in Hong Kong (288 observation sessions during 36 weekdays and 36 weekend days) and observed 28,585 visitors in 262 diverse areas/facilities. Parks were widely used throughout the day on weekdays and weekend days and across summer and autumn; visitor rates were among the highest seen in 24 SOPARC studies. In contrast to other studies where teens and children dominated park use, most visitors (71%) were adults and seniors. More males (61%) than females used the parks, and they dominated areas designed for sports. Over 60% of visitors were observed engaging in moderate-to-vigorous physical activity, a rate higher than other SOPARC studies. Facilities with user fees were less accessible than non-fee areas, but they provided relatively more supervised and organized activities. Assessing parks by age, gender, and physical activity can provide useful information relative to population health. This study not only provides information useful to local administrators for planning and programming park facilities relative to physical activity, but it also provides a baseline for comparison by other high-density cities. PMID:27367709

  17. Public Parks in Hong Kong: Characteristics of Physical Activity Areas and Their Users.

    PubMed

    Chow, Bik C; McKenzie, Thomas L; Sit, Cindy H P

    2016-01-01

    Public parks, salient locations for engaging populations in health promoting physical activity, are especially important in high-density cities. We used the System for Observing Physical Activity in Communities (SOPARC) to conduct the first-ever surveillance study of nine public parks in Hong Kong (288 observation sessions during 36 weekdays and 36 weekend days) and observed 28,585 visitors in 262 diverse areas/facilities. Parks were widely used throughout the day on weekdays and weekend days and across summer and autumn; visitor rates were among the highest seen in 24 SOPARC studies. In contrast to other studies where teens and children dominated park use, most visitors (71%) were adults and seniors. More males (61%) than females used the parks, and they dominated areas designed for sports. Over 60% of visitors were observed engaging in moderate-to-vigorous physical activity, a rate higher than other SOPARC studies. Facilities with user fees were less accessible than non-fee areas, but they provided relatively more supervised and organized activities. Assessing parks by age, gender, and physical activity can provide useful information relative to population health. This study not only provides information useful to local administrators for planning and programming park facilities relative to physical activity, but it also provides a baseline for comparison by other high-density cities. PMID:27367709

  18. A modified method for the characterisation and activity determination of large area sources.

    PubMed

    Svec, A; Janssen, H; Pernická, L; Klein, R

    2006-01-01

    Large area sources emitting alpha and beta radiations, respectively, are often used for calibrations of surface contamination monitors and meters. It is well known, however, that their properties are strongly influenced by their construction and by their active layer preparation. Non-uniformity of activity distributions over the active surface and the thickness of absorption and backscattering layers cause changes not only in the ratio of particle emission rate and activity but also in emitted particle spectra distributions. Consequently, different sources need to be characterised by one or more parameters related to their emitted particle spectra and used for their activity determination. A modified method based on simple particle absorption spectrometry has been developed. The correlation between a source characteristic parameter and its radiation detection efficiency is utilised for its activity estimation. PMID:16549354

  19. Dynamics of brain activity in motor and frontal cortical areas during music listening: a magnetoencephalographic study.

    PubMed

    Popescu, Mihai; Otsuka, Asuka; Ioannides, Andreas A

    2004-04-01

    There are formidable problems in studying how 'real' music engages the brain over wide ranges of temporal scales extending from milliseconds to a lifetime. In this work, we recorded the magnetoencephalographic signal while subjects listened to music as it unfolded over long periods of time (seconds), and we developed and applied methods to correlate the time course of the regional brain activations with the dynamic aspects of the musical sound. We showed that frontal areas generally respond with slow time constants to the music, reflecting their more integrative mode; motor-related areas showed transient-mode responses to fine temporal scale structures of the sound. The study combined novel analysis techniques designed to capture and quantify fine temporal sequencing from the authentic musical piece (characterized by a clearly defined rhythm and melodic structure) with the extraction of relevant features from the dynamics of the regional brain activations. The results demonstrated that activity in motor-related structures, specifically in lateral premotor areas, supplementary motor areas, and somatomotor areas, correlated with measures of rhythmicity derived from the music. These correlations showed distinct laterality depending on how the musical performance deviated from the strict tempo of the music score, that is, depending on the musical expression. PMID:15050586

  20. Activities and services of the U.S. Geological Survey, Denver area, Colorado

    USGS Publications Warehouse

    U.S. Geological Survey

    1969-01-01

    This booklet is a summary of the activities and services of the United States Geological Survey, written for people who have visited or plan to visit one or more of its offices in the Denver area as well as to provide general information about the Geological Survey and its work. Sources of additional information are listed on pages 42-43.

  1. Observation of electro-activated localized structures in broad area VCSELs.

    PubMed

    Parravicini, J; Brambilla, M; Columbo, L; Prati, F; Rizza, C; Tissoni, G; Agranat, A J; DelRe, E

    2014-12-01

    We demonstrate experimentally the electro-activation of a localized optical structure in a coherently driven broad-area vertical-cavity surface-emitting laser (VCSEL) operated below threshold. Control is achieved by electro-optically steering a writing beam through a pre-programmable switch based on a photorefractive funnel waveguide. PMID:25606953

  2. Doppler shift of hot coronal lines in a moss area of an active region

    NASA Astrophysics Data System (ADS)

    Dadashi, N.; Teriaca, L.; Tripathi, D.; Solanki, S. K.; Wiegelmann, T.

    2012-12-01

    The moss is the area at the footpoint of the hot (3 to 5 MK) loops forming the core of the active region where emission is believed to result from the heat flux conducted down to the transition region from the hot loops. Studying the variation of Doppler shift as a function of line formation temperatures over the moss area can give clues on the heating mechanism in the hot loops in the core of the active regions. We investigate the absolute Doppler shift of lines formed at temperatures between 1 MK and 2 MK in a moss area within active region NOAA 11243 using a novel technique that allows determining the absolute Doppler shift of EUV lines by combining observations from the SUMER and EIS spectrometers. The inner (brighter and denser) part of the moss area shows roughly constant blue shift (upward motions) of 5 km s-1 in the temperature range of 1 MK to 1.6 MK. For hotter lines the blue shift decreases and reaches 1 km s-1 for Fe xv 284 Å (~2 MK). The measurements are discussed in relation to models of the heating of hot loops. The results for the hot coronal lines seem to support the quasi-steady heating models for nonsymmetric hot loops in the core of active regions.

  3. Radiomic Texture Analysis Mapping Predicts Areas of True Functional MRI Activity

    PubMed Central

    Hassan, Islam; Kotrotsou, Aikaterini; Bakhtiari, Ali Shojaee; Thomas, Ginu A.; Weinberg, Jeffrey S.; Kumar, Ashok J.; Sawaya, Raymond; Luedi, Markus M.; Zinn, Pascal O.; Colen, Rivka R.

    2016-01-01

    Individual analysis of functional Magnetic Resonance Imaging (fMRI) scans requires user-adjustment of the statistical threshold in order to maximize true functional activity and eliminate false positives. In this study, we propose a novel technique that uses radiomic texture analysis (TA) features associated with heterogeneity to predict areas of true functional activity. Scans of 15 right-handed healthy volunteers were analyzed using SPM8. The resulting functional maps were thresholded to optimize visualization of language areas, resulting in 116 regions of interests (ROIs). A board-certified neuroradiologist classified different ROIs into Expected (E) and Non-Expected (NE) based on their anatomical locations. TA was performed using the mean Echo-Planner Imaging (EPI) volume, and 20 rotation-invariant texture features were obtained for each ROI. Using forward stepwise logistic regression, we built a predictive model that discriminated between E and NE areas of functional activity, with a cross-validation AUC and success rate of 79.84% and 80.19% respectively (specificity/sensitivity of 78.34%/82.61%). This study found that radiomic TA of fMRI scans may allow for determination of areas of true functional activity, and thus eliminate clinician bias. PMID:27151623

  4. 32 CFR Appendix C to Part 552 - Authorized Activities for Fort Lewis Maneuver Area Access

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 3 2012-07-01 2009-07-01 true Authorized Activities for Fort Lewis Maneuver Area Access C Appendix C to Part 552 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY MILITARY RESERVATIONS AND NATIONAL CEMETERIES REGULATIONS AFFECTING MILITARY RESERVATIONS Pt. 552, App. C Appendix C to Part...

  5. 32 CFR Appendix C to Part 552 - Authorized Activities for Fort Lewis Maneuver Area Access

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 3 2014-07-01 2014-07-01 false Authorized Activities for Fort Lewis Maneuver Area Access C Appendix C to Part 552 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY MILITARY RESERVATIONS AND NATIONAL CEMETERIES REGULATIONS AFFECTING MILITARY RESERVATIONS Pt. 552, App. C Appendix C to Part...

  6. 32 CFR Appendix C to Part 552 - Authorized Activities for Fort Lewis Maneuver Area Access

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 3 2013-07-01 2013-07-01 false Authorized Activities for Fort Lewis Maneuver Area Access C Appendix C to Part 552 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY MILITARY RESERVATIONS AND NATIONAL CEMETERIES REGULATIONS AFFECTING MILITARY RESERVATIONS Pt. 552, App. C Appendix C to Part...

  7. 50 CFR 218.30 - Specified activity and specified geographical area and effective dates.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Training in the Gulf of Mexico Range Complex § 218.30 Specified activity and specified geographical area...), which is located along the Gulf of Mexico coast of the U.S. described in Figures 1 and 2 of the LOA... SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE...

  8. 50 CFR 218.30 - Specified activity and specified geographical area and effective dates.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Training in the Gulf of Mexico Range Complex § 218.30 Specified activity and specified geographical area...), which is located along the Gulf of Mexico coast of the U.S. described in Figures 1 and 2 of the LOA... SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE...

  9. Overview of the CBM detector system

    NASA Astrophysics Data System (ADS)

    Balog, Tomáš

    2014-04-01

    The Compressed Baryonic Matter (CBM) experiment at the future Facility for Antiproton and Ion Research (FAIR) is a fixed target experiment designed to explore the QCD phase diagram in the region of high net-baryon densities. The CBM detector system will access beams directly from the superconducting synchrotrons SIS100 and SIS300. It is designed for interaction rates up to 107 Hz to enable measurements of rare observables and diagnostic probes created in the early and dense phase of the fireball evolution. The layout of the CBM detector system is adapted to the experimental requirements concerning the acceptance in the laboratory frame (mid and forward rapidities), reaction rates, radiation tolerance, determination of the vertices with accuracy of 50 μm, particle densities (up to 700 particles passing through the active area of the detector in single central Au+Au collision at 25 GeV/nucleon) and selectivity [1, 2].

  10. Chemical composition of soils in the areas of volcanic ashfalls around active volcanoes in Kamchatka

    NASA Astrophysics Data System (ADS)

    Zakharikhina, L. V.; Litvinenko, Yu. S.

    2016-03-01

    The geochemical features of volcanic soils (Andosols) in the northern soil province of Kamchatka are identified. The background regional concentrations ( Cb r ) of most of chemical elements in the studied soils are lower than their average concentrations in soils of the world and in the European volcanic soils. Only Na, Ca, and Mg are present in elevated concentrations in all the studied soils in the north of Kamchatka. Regional background concentrations of elements are exceeded by 1.6 times in the area of active ashfalls of the Tolbachik volcano and by 1.3 times in the area of active ashfalls of the Shiveluch volcano. The concentrations of mobile forms of elements in these areas exceed their regional background concentrations by 2.1 and 2.6 times, respectively.

  11. Development of Blocked-Impurity-Band-Type Ge Detectors Fabricated with the Surface-Activated Wafer Bonding Method for Far-Infrared Astronomy

    NASA Astrophysics Data System (ADS)

    Hanaoka, M.; Kaneda, H.; Oyabu, S.; Yamagishi, M.; Hattori, Y.; Ukai, S.; Shichi, K.; Wada, T.; Suzuki, T.; Watanabe, K.; Nagase, K.; Baba, S.; Kochi, C.

    2016-07-01

    We report the current status of the development of our new detectors for far-infrared (FIR) astronomy. We develop Blocked-Impurity-Band (BIB)-type Ge detectors to realize large-format compact arrays covering a wide FIR wavelength range up to 200 μm. We fabricated Ge junction devices of different physical parameters with a BIB-type structure, using the room temperature, surface-activated wafer bonding (SAB) method. We measured the absolute responsivity and the spectral response curve of each device at low temperatures, using an internal blackbody source in a cryostat and a Fourier transform spectrometer, respectively. The results show that the SAB Ge junction devices have significantly higher absolute responsivities and longer cut-off wavelengths of the spectral response than the conventional bulk Ge:Ga device. Based upon the results, we discuss the optimum parameters of SAB Ge junction devices for FIR detectors. We conclude that SAB Ge junction devices possess a promising applicability to next-generation FIR detectors covering wavelengths up to ˜ 200 μm with high responsivity. As a next step, we plan to fabricate a BIB-type Ge array device in combination with a low-power cryogenic readout integrated circuit.

  12. Development of Blocked-Impurity-Band-Type Ge Detectors Fabricated with the Surface-Activated Wafer Bonding Method for Far-Infrared Astronomy

    NASA Astrophysics Data System (ADS)

    Hanaoka, M.; Kaneda, H.; Oyabu, S.; Yamagishi, M.; Hattori, Y.; Ukai, S.; Shichi, K.; Wada, T.; Suzuki, T.; Watanabe, K.; Nagase, K.; Baba, S.; Kochi, C.

    2016-01-01

    We report the current status of the development of our new detectors for far-infrared (FIR) astronomy. We develop Blocked-Impurity-Band (BIB)-type Ge detectors to realize large-format compact arrays covering a wide FIR wavelength range up to 200 \\upmu m. We fabricated Ge junction devices of different physical parameters with a BIB-type structure, using the room temperature, surface-activated wafer bonding (SAB) method. We measured the absolute responsivity and the spectral response curve of each device at low temperatures, using an internal blackbody source in a cryostat and a Fourier transform spectrometer, respectively. The results show that the SAB Ge junction devices have significantly higher absolute responsivities and longer cut-off wavelengths of the spectral response than the conventional bulk Ge:Ga device. Based upon the results, we discuss the optimum parameters of SAB Ge junction devices for FIR detectors. We conclude that SAB Ge junction devices possess a promising applicability to next-generation FIR detectors covering wavelengths up to ˜ 200 \\upmu m with high responsivity. As a next step, we plan to fabricate a BIB-type Ge array device in combination with a low-power cryogenic readout integrated circuit.

  13. Development of Blocked-Impurity-Band-Type Ge Detectors Fabricated with the Surface-Activated Wafer Bonding Method for Far-Infrared Astronomy

    NASA Astrophysics Data System (ADS)

    Hanaoka, M.; Kaneda, H.; Oyabu, S.; Yamagishi, M.; Hattori, Y.; Ukai, S.; Shichi, K.; Wada, T.; Suzuki, T.; Watanabe, K.; Nagase, K.; Baba, S.; Kochi, C.

    2016-07-01

    We report the current status of the development of our new detectors for far-infrared (FIR) astronomy. We develop Blocked-Impurity-Band (BIB)-type Ge detectors to realize large-format compact arrays covering a wide FIR wavelength range up to 200 \\upmu m. We fabricated Ge junction devices of different physical parameters with a BIB-type structure, using the room temperature, surface-activated wafer bonding (SAB) method. We measured the absolute responsivity and the spectral response curve of each device at low temperatures, using an internal blackbody source in a cryostat and a Fourier transform spectrometer, respectively. The results show that the SAB Ge junction devices have significantly higher absolute responsivities and longer cut-off wavelengths of the spectral response than the conventional bulk Ge:Ga device. Based upon the results, we discuss the optimum parameters of SAB Ge junction devices for FIR detectors. We conclude that SAB Ge junction devices possess a promising applicability to next-generation FIR detectors covering wavelengths up to ˜ 200 \\upmu m with high responsivity. As a next step, we plan to fabricate a BIB-type Ge array device in combination with a low-power cryogenic readout integrated circuit.

  14. Localization of human cortical areas activated on perception of ordered and chaotic images.

    PubMed

    Fokin, V A; Shelepin, Yu E; Kharauzov, A K; Trufanov, G E; Sevost'yanov, A V; Pronin, S V; Koskin, S A

    2008-09-01

    The aims of this study were to identify the locations of areas in the human cortex responsible for describing fragmented test images of different degrees of ordering and to identify the areas taking decisions regarding stimuli of this type. The locations of higher visual functions were determined by functional magnetic resonance imaging (fMRI) using a scanner fitted with a superconducting magnet and a field strength of 1.5 T. The blood oxygen level-dependent (BOLD) method was based on measurements of the level of hemoglobin oxygenation in the blood supplied to the brain. This level was taken to be proportional to the extent of neuron activation in the corresponding part of the gray matter. Stimuli were matrixes consisting of Gabor elements of different orientations. The measure of matrix ordering was the ratio of the number of Gabor elements with identical orientations to the total number of elements in the image. Brain neurons were activated by simultaneous changes in the orientations of all the elements, leading to substitution of one matrix by another. Substitution of the orientation was perceived by observers as rotation of the elements in the matrix. Stimulation by matrixes with a high level of ordering was found to activate the occipital areas of the cortex, V1 and V2 (BA17-BA18), while presentation of matrixes with random element orientations also activated the parietal-temporal cortex, V3, V4, V5 (BA19), and the parietal area (BA7). Brain zones responsible for taking decisions regarding the level of order or chaos in the organization of the stimuli are located in different but close areas of the prefrontal and frontal cortex of the brain, including BA6, BA9, and BA10. The results are assessed in terms of concepts of the roles and interactions of different areas of the human brain during recognition of fragmented images of different degrees of complexity. PMID:18720013

  15. Fiber optic detector

    NASA Astrophysics Data System (ADS)

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

    1990-04-01

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

  16. Fiber optic detector

    SciTech Connect

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

    1990-12-31

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

  17. Brain areas activated by uncertain reward-based decision-making in healthy volunteers

    PubMed Central

    Guo, Zongjun; Chen, Juan; Liu, Shien; Li, Yuhuan; Sun, Bo; Gao, Zhenbo

    2013-01-01

    Reward-based decision-making has been found to activate several brain areas, including the ventrolateral prefrontal lobe, orbitofrontal cortex, anterior cingulate cortex, ventral striatum, and mesolimbic dopaminergic system. In this study, we observed brain areas activated under three degrees of uncertainty in a reward-based decision-making task (certain, risky, and ambiguous). The tasks were presented using a brain function audiovisual stimulation system. We conducted brain scans of 15 healthy volunteers using a 3.0T magnetic resonance scanner. We used SPM8 to analyze the location and intensity of activation during the reward-based decision-making task, with respect to the three conditions. We found that the orbitofrontal cortex was activated in the certain reward condition, while the prefrontal cortex, precentral gyrus, occipital visual cortex, inferior parietal lobe, cerebellar posterior lobe, middle temporal gyrus, inferior temporal gyrus, limbic lobe, and midbrain were activated during the ‘risk’ condition. The prefrontal cortex, temporal pole, inferior temporal gyrus, occipital visual cortex, and cerebellar posterior lobe were activated during ambiguous decision-making. The ventrolateral prefrontal lobe, frontal pole of the prefrontal lobe, orbitofrontal cortex, precentral gyrus, inferior temporal gyrus, fusiform gyrus, supramarginal gyrus, inferior parietal lobule, and cerebellar posterior lobe exhibited greater activation in the ‘risk’ than in the ‘certain’ condition (P < 0.05). The frontal pole and dorsolateral region of the prefrontal lobe, as well as the cerebellar posterior lobe, showed significantly greater activation in the ‘ambiguous’ condition compared to the ‘risk’ condition (P < 0.05). The prefrontal lobe, occipital lobe, parietal lobe, temporal lobe, limbic lobe, midbrain, and posterior lobe of the cerebellum were activated during decision-making about uncertain rewards. Thus, we observed different levels and regions of

  18. The Importance of Landscape Elements for Bat Activity and Species Richness in Agricultural Areas.

    PubMed

    Heim, Olga; Treitler, Julia T; Tschapka, Marco; Knörnschild, Mirjam; Jung, Kirsten

    2015-01-01

    Landscape heterogeneity is regarded as a key factor for maintaining biodiversity and ecosystem function in production landscapes. We investigated whether grassland sites at close vicinity to forested areas are more frequently used by bats. Considering that bats are important consumers of herbivorous insects, including agricultural pest, this is important for sustainable land management. Bat activity and species richness were assessed using repeated monitoring from May to September in 2010 with acoustic monitoring surveys on 50 grassland sites in the Biosphere Reserve Schorfheide-Chorin (North-East Germany). Using spatial analysis (GIS), we measured the closest distance of each grassland site to potentially connecting landscape elements (e.g., trees, linear vegetation, groves, running and standing water). In addition, we assessed the distance to and the percent land cover of forest remnants and urban areas in a 200 m buffer around the recording sites to address differences in the local landscape setting. Species richness and bat activity increased significantly with higher forest land cover in the 200 m buffer and at smaller distance to forested areas. Moreover, species richness increased in proximity to tree groves. Larger amount of forest land cover and smaller distance to forest also resulted in a higher activity of bats on grassland sites in the beginning of the year during May, June and July. Landscape elements near grassland sites also influenced species composition of bats and species richness of functional groups (open, edge and narrow space foragers). Our results highlight the importance of forested areas, and suggest that agricultural grasslands that are closer to forest remnants might be better buffered against outbreaks of agricultural pest insects due to higher species richness and higher bat activity. Furthermore, our data reveals that even for highly mobile species such as bats, a very dense network of connecting elements within the landscape is

  19. The Importance of Landscape Elements for Bat Activity and Species Richness in Agricultural Areas

    PubMed Central

    Heim, Olga; Treitler, Julia T.; Tschapka, Marco; Knörnschild, Mirjam; Jung, Kirsten

    2015-01-01

    Landscape heterogeneity is regarded as a key factor for maintaining biodiversity and ecosystem function in production landscapes. We investigated whether grassland sites at close vicinity to forested areas are more frequently used by bats. Considering that bats are important consumers of herbivorous insects, including agricultural pest, this is important for sustainable land management. Bat activity and species richness were assessed using repeated monitoring from May to September in 2010 with acoustic monitoring surveys on 50 grassland sites in the Biosphere Reserve Schorfheide-Chorin (North-East Germany). Using spatial analysis (GIS), we measured the closest distance of each grassland site to potentially connecting landscape elements (e.g., trees, linear vegetation, groves, running and standing water). In addition, we assessed the distance to and the percent land cover of forest remnants and urban areas in a 200 m buffer around the recording sites to address differences in the local landscape setting. Species richness and bat activity increased significantly with higher forest land cover in the 200 m buffer and at smaller distance to forested areas. Moreover, species richness increased in proximity to tree groves. Larger amount of forest land cover and smaller distance to forest also resulted in a higher activity of bats on grassland sites in the beginning of the year during May, June and July. Landscape elements near grassland sites also influenced species composition of bats and species richness of functional groups (open, edge and narrow space foragers). Our results highlight the importance of forested areas, and suggest that agricultural grasslands that are closer to forest remnants might be better buffered against outbreaks of agricultural pest insects due to higher species richness and higher bat activity. Furthermore, our data reveals that even for highly mobile species such as bats, a very dense network of connecting elements within the landscape is

  20. 'Syntactic Perturbation' During Production Activates the Right IFG, but not Broca's Area or the ATL.

    PubMed

    Matchin, William; Hickok, Gregory

    2016-01-01

    Research on the neural organization of syntax - the core structure-building component of language - has focused on Broca's area and the anterior temporal lobe (ATL) as the chief candidates for syntactic processing. However, these proposals have received considerable challenges. In order to better understand the neural basis of syntactic processing, we performed a functional magnetic resonance imaging experiment using a constrained sentence production task. We examined the BOLD response to sentence production for active and passive sentences, unstructured word lists, and syntactic perturbation. Perturbation involved cued restructuring of the planned syntax of a sentence mid utterance. Perturbation was designed to capture the effects of syntactic violations previously studied in sentence comprehension. Our experiment showed that Broca's area and the ATL did not exhibit response profiles consistent with syntactic operations - we found no increase of activation in these areas for sentences > lists or for perturbation. Syntactic perturbation activated a cortical-subcortical network including robust activation of the right inferior frontal gyrus (RIFG). This network is similar to one previously shown to be involved in motor response inhibition. We hypothesize that RIFG activation in our study and in previous studies of sentence comprehension is due to an inhibition mechanism that may facilitate efficient syntactic restructuring. PMID:26941692

  1. On the abundance and activity pattern of zoobenthos inhabiting a tropical reef area, Cebu, Philippines

    NASA Astrophysics Data System (ADS)

    Faubel, A.

    1984-12-01

    A benthic faunal study was carried out in the tidal area of Mactan Island (Cebu, Philippines). The area was subdivided along a transect from the beach to the reef according to benthic assemblages. The sediments are largely composed of calcareous skeletal remains of the indigenous biota and surrounding calcareous rocks. The content of protein and carbohydrates of the sediment was estimated, providing an approximation of organic matter in terms of feeding efficiency. Total number of zoobenthos, both as regards the sediment samples and as to the epifaunal communities associated with seaweeds, is rather uniformly distributed justifying the 95% confidence level ( P>0.05). Distinct differences are apparent in abundance values of individual taxa. Although the study area showed the expected distribution pattern, with dominance of Nematoda (39%) living in sediment and Harpacticoida (36 66%) dwelling on Thalassia and algae, Polychaeta reveal a dominant attraction to both these habitats. The reasons for this phenomenon are discussed in relation to the absolute lack of macrofaunal predators The zoobenthos adjust their distribution and activity to fluctuating conditions of the environment. Light is mainly suggested as stimulating diel migration activities of the benthic fauna, moving upwards from the sediment to the algae and Thalassia during daytime. In a field experiment the zoobenthos was investigated for digestion activity over a diurnal cycle. The results reveal that feeding activity of zoobenthos follows a diel cycle showing maximum activity during the morning and evening obviously influenced by changes of light.

  2. Radiation hardness characteristics of Si-PIN radiation detectors

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  3. Comparison of the locomotor activating effects of bicuculline infusions into the preoptic area and ventral pallidum

    PubMed Central

    Zahm, Daniel S.; Schwartz, Zachary M.; Lavezzi, Heather N.; Yetnikoff, Leora; Parsley, Kenneth P.

    2013-01-01

    Ambulatory locomotion in the rodent is robustly activated by unilateral infusions into the basal forebrain of type A gamma-aminobutyric acid (GABAA) receptor antagonists, such as bicuculline and picrotoxin. The present study was carried out to better localize the neuroanatomical substrate(s) underlying this effect. To accomplish this, differences in total locomotion accumulated during a 20 minute test period following bicuculline versus saline infusions in male Sprague-Dawley rats were calculated, rank ordered and mapped on a diagram of basal forebrain transposed from immunoprocessed sections. The most robust locomotor activation was elicited by bicuculline infusions clustered in rostral parts of the preoptic area. Unilateral infusions of bicuculline into the ventral pallidum produced an unanticipatedly diminutive activation of locomotion, which led us to evaluate bilateral ventral pallidal infusions, and these also produced only a small activation of locomotion, and, interestingly, a non-significant trend toward suppression of rearing. Subjects with bicuculline infused bilaterally into the ventral pallidum also exhibited persistent bouts of abnormal movements. Bicuculline infused unilaterally into other forebrain structures, including the bed nucleus of stria terminalis, caudate-putamen, globus pallidus, sublenticular extended amygdala and sublenticular substantia innominata, did not produce significant locomotor activation. Our data identify the rostral preoptic area as the main substrate for the locomotor activating effects of basal forebrain bicuculline infusions. In contrast, slight activation of locomotion and no effect on rearing accompanied unilateral and bilateral ventral pallidal infusions. Implications of these findings for forebrain processing of reward are discussed. PMID:23423460

  4. Fire Detector

    NASA Technical Reports Server (NTRS)

    1978-01-01

    An early warning fire detection sensor developed for NASA's Space Shuttle Orbiter is being evaluated as a possible hazard prevention system for mining operations. The incipient Fire Detector represents an advancement over commercially available smoke detectors in that it senses and signals the presence of a fire condition before the appearance of flame and smoke, offering an extra margin of safety.

  5. Metal Detectors.

    ERIC Educational Resources Information Center

    Harrington-Lueker, Donna

    1992-01-01

    Schools that count on metal detectors to stem the flow of weapons into the schools create a false sense of security. Recommendations include investing in personnel rather than hardware, cultivating the confidence of law-abiding students, and enforcing discipline. Metal detectors can be quite effective at afterschool events. (MLF)

  6. Small-molecule endothelin receptor antagonists: a review of patenting activity across therapeutic areas.

    PubMed

    Mucke, Hermann A M

    2009-06-01

    In the field of nonpeptide NCEs with endothelin receptor antagonist activity, a burst in corporate IP filings occurred in the 1990s once the human endothelin system had been characterized, but patent activity has declined in the past decade. Universities have not been active in this area of research to a degree that would have led to many patent applications. While three endothelin receptor antagonists (bosentan, sitaxentan and ambrisentan) are already available for the treatment of pulmonary arterial hypertension, the use of such compounds for the larger therapy areas of heart failure, cancer and nephropathy is still being evaluated in late-stage clinical trials. Marketed and advanced-stage endothelin receptor blockers have remarkably little chemical diversity; thus, the substantially larger chemical space defined by patenting remains to be explored. PMID:19517317

  7. Automaticity and localisation of concurrents predicts colour area activity in grapheme-colour synaesthesia.

    PubMed

    Gould van Praag, Cassandra D; Garfinkel, Sarah; Ward, Jamie; Bor, Daniel; Seth, Anil K

    2016-07-29

    In grapheme-colour synaesthesia (GCS), the presentation of letters or numbers induces an additional 'concurrent' experience of colour. Early functional MRI (fMRI) investigations of GCS reported activation in colour-selective area V4 during the concurrent experience. However, others have failed to replicate this key finding. We reasoned that individual differences in synaesthetic phenomenology might explain this inconsistency in the literature. To test this hypothesis, we examined fMRI BOLD responses in a group of grapheme-colour synaesthetes (n=20) and matched controls (n=20) while characterising the individual phenomenology of the synaesthetes along dimensions of 'automaticity' and 'localisation'. We used an independent functional localiser to identify colour-selective areas in both groups. Activations in these areas were then assessed during achromatic synaesthesia-inducing, and non-inducing conditions; we also explored whole brain activations, where we sought to replicate the existing literature regarding synaesthesia effects. Controls showed no significant activations in the contrast of inducing > non-inducing synaesthetic stimuli, in colour-selective ROIs or at the whole brain level. In the synaesthete group, we correlated activation within colour-selective ROIs with individual differences in phenomenology using the Coloured Letters and Numbers (CLaN) questionnaire which measures, amongst other attributes, the subjective automaticity/attention in synaesthetic concurrents, and their spatial localisation. Supporting our hypothesis, we found significant correlations between individual measures of synaesthetic phenomenology and BOLD responses in colour-selective areas, when contrasting inducing against non-inducing stimuli. Specifically, left-hemisphere colour area responses were stronger for synaesthetes scoring high on phenomenological localisation and automaticity/attention, while right-hemisphere colour area responses showed a relationship with localisation

  8. Spontaneous activations follow a common developmental course across primary sensory areas in mouse neocortex.

    PubMed

    Frye, Charles G; MacLean, Jason N

    2016-08-01

    Spontaneous propagation of spiking within the local neocortical circuits of mature primary sensory areas is highly nonrandom, engaging specific sets of interconnected and functionally related neurons. These spontaneous activations promise insight into neocortical structure and function, but their properties in the first 2 wk of perinatal development are incompletely characterized. Previously, we have found that there is a minimal numerical sample, on the order of 400 cells, necessary to fully capture mature neocortical circuit dynamics. Therefore we maximized our numerical sample by using two-photon calcium imaging to observe spontaneous activity in populations of up to 1,062 neurons spanning multiple columns and layers in 52 acute coronal slices of mouse neocortex at each day from postnatal day (PND) 3 to PND 15. Slices contained either primary auditory cortex (A1) or somatosensory barrel field (S1BF), which allowed us to compare sensory modalities with markedly different developmental timelines. Between PND 3 and PND 8, populations in both areas exhibited activations of anatomically compact subgroups on the order of dozens of cells. Between PND 9 and PND 13, the spatiotemporal structure of the activity diversified to include spatially distributed activations encompassing hundreds of cells. Sparse activations covering the entire field of view dominated in slices taken on or after PND 14. These and other findings demonstrate that the developmental progression of spontaneous activations from active local modules in the first postnatal week to sparse, intermingled groups of neurons at the beginning of the third postnatal week generalizes across primary sensory areas, consistent with an intrinsic developmental trajectory independent of sensory input. PMID:27146981

  9. Nano-optical observation of cascade switching in a parallel superconducting nanowire single photon detector

    SciTech Connect

    Heath, Robert M. Tanner, Michael G.; Casaburi, Alessandro; Hadfield, Robert H.; Webster, Mark G.; San Emeterio Alvarez, Lara; Jiang, Weitao; Barber, Zoe H.; Warburton, Richard J.

    2014-02-10

    The device physics of parallel-wire superconducting nanowire single photon detectors is based on a cascade process. Using nano-optical techniques and a parallel wire device with spatially separate pixels, we explicitly demonstrate the single- and multi-photon triggering regimes. We develop a model for describing efficiency of a detector operating in the arm-trigger regime. We investigate the timing response of the detector when illuminating a single pixel and two pixels. We see a change in the active area of the detector between the two regimes and find the two-pixel trigger regime to have a faster timing response than the one-pixel regime.

  10. High-resolution pulse-counting array detectors for imaging and spectroscopy at ultraviolet wavelengths

    NASA Technical Reports Server (NTRS)

    Timothy, J. Gethyn; Bybee, Richard L.

    1986-01-01

    The performance characteristics of multianode microchannel array (MAMA) detector systems which have formats as large as 256 x 1024 pixels and which have application to imaging and spectroscopy at UV wavelengths are evaluated. Sealed and open-structure MAMA detector tubes with opaque CsI photocathodes can determine the arrival time of the detected photon to an accuracy of 100 ns or better. Very large format MAMA detectors with CsI and Cs2Te photocathodes and active areas of 52 x 52 mm (2048 x 2048 pixels) will be used as the UV solar blind detectors for the NASA STIS.

  11. 78 FR 13712 - U.S. Nuclear Regulatory Commission Planned Monitoring Activities for F-Area Tank Farm at the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-28

    ... COMMISSION U.S. Nuclear Regulatory Commission Planned Monitoring Activities for F-Area Tank Farm at the... Savannah River Site F-Area Tank Farm Facility in Accordance with the National Defense Authorization Act for... DOE's waste disposal activities at the F-Area Tank Farm at the Savannah River Site, in accordance...

  12. [Localization of human brain areas activated for chaotic and ordered pattern perception].

    PubMed

    Fokin, V A; Shelepin, Iu E; Kharauzov, A K; Trufanov, G E; Sevost'ianov, A V; Pronin, S V; Koskin, S A

    2007-10-01

    The aim of our work was to localize cortical areas involved in the processing of incomplete figures using functional MRI (fMRI) for 8 healthy volunteers (18-30 year old) with the did of anatomical and fMRI fast imaging technique: echo planar imaging (EPI), whole brain scan (36 slices) matrix 64 x 64, 3.7 second. We used 1.5 T MR-scanner and BOLD-method (Blood Oxygenation Level Dependent), based on distinctions of magnetic properties of hemoglobin. Fast imaging technique on modern MR-scanners with > or = 1.5 T provides precise statistical maps of oxygenation increase with high spatial resolution. For test stimuli we used matrix of Gabor grating. We used two types of 10 x 10 matrices with chaotic and ordered orientation of Gabor gratings. The size, brightness and contrast of the stimuli were identical. The chaotic and ordered patterns activated different brain areas. We establish that ordered patterns activated only primary visual cortex - V1 and V2, (BA17-18), wheareas chaotic patterns activated in addition primary visual cortex, the V3,V4,V5 (BA19) of the occipital cortex and the area 7 of parietal area (BA7) classification. Decision making for that task is localized in prefrontal and frontal cortex, including (BA 6, 9, 10). PMID:18074783

  13. Silent play in a loud theatre - soil development in a geomorphically active proglacial area

    NASA Astrophysics Data System (ADS)

    Harlaar, Piet; Temme, Arnaud; Heckmann, Tobias

    2015-04-01

    Proglacial areas are scientifically famous for two sets of processes: first, the tumultuous geomorphic response to glacial retreat including enhanced fluvial activity and mass movements such as debris flows, rock fall and landslides. Second, the slow and somewhat regular development of soil and vegetation. These two sets of processes have usually been studied in isolation: soil development is best observed in wide, flat proglacial areas where not much geomorphic work is done. This has left questions unanswered that relate to the effect of geomorphic disturbance on high mountain soil formation, and vice versa. We attempted to characterize these interactions in the geomorphically active proglacial area of the Gepatsch Ferner in the Kaunertal in Austria. Geomorphic activity in this area is intensively studied in the PROSA project. In our study, several dozen soils were sampled in order to describe soil properties. Sampling locations were selected with Latin Hypercube sampling to best cover the variation in soil-forming factors. Results clearly showed that soil properties were not only a function of age, but also of erosion-deposition amounts and geomorphic regime. In contrast to what is reported in literature, soil pH in very young soils rose before it dropped as soils became older. The early pH rise probably reflects the leaching of pyrite in the parent material.

  14. On the area expansion of magnetic flux tubes in solar active regions

    SciTech Connect

    Dudík, Jaroslav; Dzifčáková, Elena; Cirtain, Jonathan W. E-mail: elena@asu.cas.cz

    2014-11-20

    We calculated the three-dimensional (3D) distribution of the area expansion factors in a potential magnetic field, extrapolated from the high-resolution Hinode/SOT magnetogram of the quiescent active region NOAA 11482. Retaining only closed loops within the computational box, we show that the distribution of area expansion factors show significant structure. Loop-like structures characterized by locally lower values of the expansion factor are embedded in a smooth background. These loop-like flux tubes have squashed cross-sections and expand with height. The distribution of the expansion factors show an overall increase with height, allowing an active region core characterized by low values of the expansion factor to be distinguished. The area expansion factors obtained from extrapolation of the Solar Optical Telescope magnetogram are compared to those obtained from an approximation of the observed magnetogram by a series of 134 submerged charges. This approximation retains the general flux distribution in the observed magnetogram, but removes the small-scale structure in both the approximated magnetogram and the 3D distribution of the area expansion factors. We argue that the structuring of the expansion factor can be a significant ingredient in producing the observed structuring of the solar corona. However, due to the potential approximation used, these results may not be applicable to loops exhibiting twist or to active regions producing significant flares.

  15. Site-specific characterization of Castromil Brownfield area related to gold mining activities.

    PubMed

    Ferreira da Silva, Eduardo; Serrano Pinto, Luís; Patinha, Carla; Cardoso Fonseca, Edmundo

    2004-03-01

    Castromil is one of the gold mining areas in Portugal that has been abandoned since 1940. This area, which was first mined in Roman times, is located within a Hercynian granite body near the contact with Silurian metasediments. Gold is essentially disseminated along veins in the silicified granite, running NW-SE, related with a shear zone and frequently associated with sulphides (arsenopyrite and basically pyrite). In paragenetic terms, three stages of mineralization are considered: ferro-arseniferous (quartz + arsenopyrite I + pyrite I + pyrrhotite + bismuth), zinciferous (sphalerite + chalcopyrite), and remobilization (arsenopyrite II + galena + gold). Due to the lack of laws and environmental education, Castromil is today a gold mining heritage site where we can detect the consequences of an incautious exploration (tailings, wells and adits located in the old explored zone) and where a residential area is located. In order to characterize the actual state of the old mining area the trace metal contamination of soils and waters by mining activities was investigated. In the studied area 106 soil samples, 15 waters and 20 plants were sampled and analysed. The soil samples were analysed for 32 elements by ICP-AES. Waters were analysed by ionic chromatography and ICP-MS for major and trace elements. Plants were analysed for As, Fe and Pb by AAS. The results are discussed taking into account the risk-based standards for soils and groundwater's (target and intervention values) proposed by Swartjes (1999). The results show elevated concentration of As and Pb which were found in soils collected from agricultural areas. Foodstuff plants species collected in the Castromil agricultural area show high concentrations of As in the leaves (cabbage and lettuce) and in the tubers (potatoes). Groundwaters in the mining area contain high concentrations of As that exceeds the intervention values. The area must to be subject to a remediation process, considering the actual risks to

  16. Activity in early visual areas predicts interindividual differences in binocular rivalry dynamics

    PubMed Central

    Yamashiro, Hiroyuki; Mano, Hiroaki; Umeda, Masahiro; Higuchi, Toshihiro; Saiki, Jun

    2013-01-01

    When dissimilar images are presented to the two eyes, binocular rivalry (BR) occurs, and perception alternates spontaneously between the images. Although neural correlates of the oscillating perception during BR have been found in multiple sites along the visual pathway, the source of BR dynamics is unclear. Psychophysical and modeling studies suggest that both low- and high-level cortical processes underlie BR dynamics. Previous neuroimaging studies have demonstrated the involvement of high-level regions by showing that frontal and parietal cortices responded time locked to spontaneous perceptual alternation in BR. However, a potential contribution of early visual areas to BR dynamics has been overlooked, because these areas also responded to the physical stimulus alternation mimicking BR. In the present study, instead of focusing on activity during perceptual switches, we highlighted brain activity during suppression periods to investigate a potential link between activity in human early visual areas and BR dynamics. We used a strong interocular suppression paradigm called continuous flash suppression to suppress and fluctuate the visibility of a probe stimulus and measured retinotopic responses to the onset of the invisible probe using functional MRI. There were ∼130-fold differences in the median suppression durations across 12 subjects. The individual differences in suppression durations could be predicted by the amplitudes of the retinotopic activity in extrastriate visual areas (V3 and V4v) evoked by the invisible probe. Weaker responses were associated with longer suppression durations. These results demonstrate that retinotopic representations in early visual areas play a role in the dynamics of perceptual alternations during BR. PMID:24353304

  17. Multisensor mine detector for peacekeeping: improved landmine detector concept (ILDC)

    NASA Astrophysics Data System (ADS)

    McFee, John E.; Carruthers, Al

    1996-05-01

    The Improved Landmine Detector Concept Project was initiated in Autumn 1994 to develop a prototype vehicle mounted mine detector for low metal content and nonmetallic mines for a peacekeeping role on roads. The system will consist of a teleoperated vehicle carrying a highly sensitive electromagnetic induction (EMI) detector, an infrared imager (IR), ground probing radar (GPR), and a thermal neutron activation (TNA) detector for confirmation. The IR, EMI and TNA detectors have been under test since 1995 and the GPR will be received in June 1996. Results of performance trials of the individual detectors are discussed. Various design configurations and their tradeoffs are discussed. Fusion of data from the detectors to reduce false alarm rate and increase probability of detection, a key element to the success of the system, is discussed. An advanced development model of the system is expected to be complete by Spring 1997.

  18. Characterization of the KID-Based Light Detectors of CALDER

    NASA Astrophysics Data System (ADS)

    Casali, N.; Bellini, F.; Cardani, L.; Castellano, M. G.; Colantoni, I.; Coppolecchia, A.; Cosmelli, C.; Cruciani, A.; D'Addabbo, A.; Di Domizio, S.; Martinez, M.; Tomei, C.; Vignati, M.

    2016-07-01

    The aim of the Cryogenic wide-Area Light Detectors with Excellent Resolution (CALDER) project is the development of light detectors with active area of 5 × 5 cm2 and noise energy resolution smaller than 20 eV RMS, implementing phonon-mediated kinetic inductance detectors. The detectors are developed to improve the background suppression in large-mass bolometric experiments such as CUORE, via the double read-out of the light and the heat released by particles interacting in the bolometers. In this work, we present the characterization of the first light detectors developed by CALDER. We describe the analysis tools to evaluate the resonator parameters (resonant frequency and quality factors) taking into account simultaneously all the resonance distortions introduced by the read-out chain (as the feed-line impedance and its mismatch) and by the power stored in the resonator itself. We detail the method for the selection of the optimal point for the detector operation (maximizing the signal-to-noise ratio). Finally, we present the response of the detector to optical pulses in the energy range of 0{-}30 keV.

  19. Characterization of the KID-Based Light Detectors of CALDER

    NASA Astrophysics Data System (ADS)

    Casali, N.; Bellini, F.; Cardani, L.; Castellano, M. G.; Colantoni, I.; Coppolecchia, A.; Cosmelli, C.; Cruciani, A.; D'Addabbo, A.; Di Domizio, S.; Martinez, M.; Tomei, C.; Vignati, M.

    2015-11-01

    The aim of the Cryogenic wide-Area Light Detectors with Excellent Resolution (CALDER) project is the development of light detectors with active area of 5 × 5 cm2 and noise energy resolution smaller than 20 eV RMS, implementing phonon-mediated kinetic inductance detectors. The detectors are developed to improve the background suppression in large-mass bolometric experiments such as CUORE, via the double read-out of the light and the heat released by particles interacting in the bolometers. In this work, we present the characterization of the first light detectors developed by CALDER. We describe the analysis tools to evaluate the resonator parameters (resonant frequency and quality factors) taking into account simultaneously all the resonance distortions introduced by the read-out chain (as the feed-line impedance and its mismatch) and by the power stored in the resonator itself. We detail the method for the selection of the optimal point for the detector operation (maximizing the signal-to-noise ratio). Finally, we present the response of the detector to optical pulses in the energy range of 0{-}30 keV.

  20. Touching a rubber hand: feeling of body ownership is associated with activity in multisensory brain areas.

    PubMed

    Ehrsson, H Henrik; Holmes, Nicholas P; Passingham, Richard E

    2005-11-01

    In the "rubber-hand illusion," the sight of brushing of a rubber hand at the same time as brushing of the person's own hidden hand is sufficient to produce a feeling of ownership of the fake hand. We shown previously that this illusion is associated with activity in the multisensory areas, most notably the ventral premotor cortex (Ehrsson et al., 2004). However, it remains to be demonstrated that this illusion does not simply reflect the dominant role of vision and that the premotor activity does not reflect a visual representation of an object near the hand. To address these issues, we introduce a somatic rubber-hand illusion. The experimenter moved the blindfolded participant's left index finger so that it touched the fake hand, and simultaneously, he touched the participant's real right hand, synchronizing the touches as perfectly as possible. After approximately 9.7 s, this stimulation elicited an illusion that one was touching one's own hand. We scanned brain activity during this illusion and two control conditions, using functional magnetic resonance imaging. Activity in the ventral premotor cortices, intraparietal cortices, and the cerebellum was associated with the illusion of touching one's own hand. Furthermore, the rated strength of the illusion correlated with the degree of premotor and cerebellar activity. This finding suggests that the activity in these areas reflects the detection of congruent multisensory signals from one's own body, rather than of visual representations. We propose that this could be the mechanism for the feeling of body ownership. PMID:16280594

  1. Gaseous Detectors

    NASA Astrophysics Data System (ADS)

    Titov, Maxim

    Since long time, the compelling scientific goals of future high-energy physics experiments were a driving factor in the development of advanced detector technologies. A true innovation in detector instrumentation concepts came in 1968, with the development of a fully parallel readout for a large array of sensing elements - the Multi-Wire Proportional Chamber (MWPC), which earned Georges Charpak a Nobel prize in physics in 1992. Since that time radiation detection and imaging with fast gaseous detectors, capable of economically covering large detection volumes with low mass budget, have been playing an important role in many fields of physics. Advances in photolithography and microprocessing techniques in the chip industry during the past decade triggered a major transition in the field of gas detectors from wire structures to Micro-Pattern Gas Detector (MPGD) concepts, revolutionizing cell-size limitations for many gas detector applications. The high radiation resistance and excellent spatial and time resolution make them an invaluable tool to confront future detector challenges at the next generation of colliders. The design of the new micro-pattern devices appears suitable for industrial production. Novel structures where MPGDs are directly coupled to the CMOS pixel readout represent an exciting field allowing timing and charge measurements as well as precise spatial information in 3D. Originally developed for the high-energy physics, MPGD applications have expanded to nuclear physics, photon detection, astroparticle and neutrino physics, neutron detection, and medical imaging.

  2. Development of a large area InGaAs APD receiver based on an impact ionization engineered detector for free-space lasercomm applications

    NASA Astrophysics Data System (ADS)

    Burris, H. R.; Ferraro, M. S.; Freeman, W. T.; Moore, C. I.; Murphy, J. L.; Rabinovich, W. S.; Smith, W. R.; Summers, L. L.; Thomas, L. M.; Vilcheck, M. J.; Clark, W. R.; Waters, W. D.

    2012-06-01

    The U.S. Naval Research Laboratory (NRL) is developing a small size, weight and power (SWaP) free space lasercomm terminal for small unmanned airborne platforms. The terminal is based on a small gimbal developed by CloudCap Technology. A receiver with a large field of view and with sensitivity sufficient to meet the program range goals is required for this terminal. An InGaAs Avalanche Photodiode (APD) with internal structures engineered to reduce excess noise and keff in high gain applications was selected as the detector. The detector is a 350 micron diameter impact ionization engineered (I2E) APD developed by Optogration, Inc. Results of development and characterization of the receiver will be presented.

  3. Time series analysis of thermal variation on Italian volcanic active areas by using IR satellite data

    NASA Astrophysics Data System (ADS)

    Silvestri, M.; Buongiorno, M. F.; Pieri, D. C.

    2014-12-01

    To monitoring of active volcanoes the systematic acquisition of medium/high resolution thermal data and the subsequent analysis of time series may improve the capability to detect small surface temperature variation related to changes in volcanic activity level and contribute to the early warning systems. Examples on the processing of long time series based EO data of Mt Etna activity and Phlegraean Fields observation by using remote sensing techniques and at different spatial resolution data (ASTER - 90mt, AVHRR -1km, MODIS-1km, MSG SEVIRI-3km) are showed. The use of TIR sensors with high spatial resolution offers the possibility to obtain detailed information on the areas where there are significant changes, detecting variation in fumaroles fields and summit craters before eruptions. Thanks to ASTER thermal infrared (TIR, 5 bands) regions of the electromagnetic spectrum we have obtained the surface temperature map on the volcano area. For this study we have considered the ASTER's night observations that show well defined episodes of increasing thermal emission of crater thanks to a more uniform background temperature. Two different procedures are shown, both using the TIR high spatial resolution data: for Phlegraean Fields (active but quiescent volcano) the analysis of time series of surface temperature which may improve the capability to detect small surface temperature variation related to changes in volcanic activity level; for Mt. Etna (active volcano) a semi-automatic procedure which extract the summit area radiance values with the goal of detecting variation related to eruptive events. The advantage of direct download of EO data by means INGV antennas even though low spatial resolution offers the possibility of a systematic data processing having a daily updating of information for prompt response and hazard mitigation. At the same time the comparison of surface temperature retrievals at different scale is an important issue for future satellite sensors.

  4. Ion detection with a cryogenic detector compared to a microchannel plate detector in MALDI TOF-MS

    SciTech Connect

    Benner, W H; Frank, M; Labov, S; Westmacott, G; Zhong, F

    1999-06-29

    Detection of molecular ions in mass spectrometry is typically accomplished by an ion colliding with a surface and then amplifying the emitted secondary electrons. It is well established that the secondary electron yield decreases as the mass of the primary ion increases [1-3], thus limiting the detection efficiency of large molecular ions. One way around this limitation is to use secondary ion detectors because the emission efficiency of secondary ions does not seem to decrease for increasing primary ion mass [1]. However this technique has limitations in timing resolution because of the mass spread of the emitted secondary ions. To find other ways around high mass detection limitations it is important to understand existing mechanisms of detection and to explore alternative detector types. To this end, a superconducting tunnel junction (STJ) detector was used in measuring the secondary electron emission efficiency, se, for a MCP detector. STJ detectors are energy sensitive and do not rely on secondary emission to produce a signal. Using a linear MALDI-TOF mass spectrometer, a STJ detector is mounted directly behind the hole in an annular MCP detector. This mounting arrangement allows ions to be detected simultaneously by each detector. The STJ detector sits in a liquid helium cryostat and is operated at 1.3 K to minimize thermal noise (see [4,5] for more details). Primary ions passing through the center hole of the MCP detector collide with the 0.04 mm{sup 2} STJ surface and generate a detector-pulse that is approximately proportional to the ion's total energy. A mask with a small hole in it was placed in front of the MCP detector so that the MCP and STJ detectors have approximately the same effective active areas. The ion beam diameter near the MCP is over 2.5 cm (measured with a MCP-phosphorus screen detector) and the axial separation of the two detectors is about 4 mm. Both detectors were operated in pulse-counting mode and set to have the same effective

  5. The role of activator concentration and precipitate formation on optical and dosimetric properties of KCl:Eu2+ storage phosphor detectors

    PubMed Central

    Hansel, Rachael A.; Xiao, Zhiyan; Hu, Yanle; Green, Olga; Yang, Deshan; Harold Li, H.

    2013-01-01

    Purpose: The activator ion (Eu2+ in KCl:Eu2+) plays an important role in the photostimulated luminescence (PSL) mechanism of storage phosphor radiation detectors. In order to design an accurate, effective, and robust detector, it is important to understand how the activator ion concentration affects the structure and, consequently, radiation detection properties of KCl:Eu2+. Methods: Potassium chloride pellets were fabricated with various amounts of europium dopant (0.01–5.0 mol.% Eu2+). Clinical radiation doses were given with a 6 MV linear accelerator. Radiation doses larger than 100 Gy were given with a 137Cs irradiator. Dose response curves, radiation hardness, and temporal signal stability were measured using a laboratory PSL readout system. The crystal structure of the material was studied using x ray diffraction and luminescence spectroscopy. Results: The most intense PSL signal was from samples with 1.0 mol.% Eu. However, samples with concentrations higher than 0.05 mol.% Eu exhibited significant degradation in PSL intensity for cumulated doses larger than 3000 Gy. Structural and luminescence spectroscopy showed clear evidence of precipitate phases within the KCl lattice, especially for high activator concentrations. Analysis of PL emission spectra showed that interactions between Eu-Vc dipoles and Eu-Vc trimers could explain trends in PSL sensitivity and radiation hardness observations. Conclusions: The concentration of the activator ion (Eu2+) significantly affects radiation detection properties of the storage phosphor KCl:Eu2+. An activator concentration between 0.01 and 0.05 mol.% Eu in KCl:Eu2+ storage phosphor detectors is recommended for linear dose response, good PSL sensitivity, predictable temporal stability, and high reusability for megavoltage radiation detection. PMID:24007173

  6. Social safety, self-rated general health and physical activity: changes in area crime, area safety feelings and the role of social cohesion.

    PubMed

    Ruijsbroek, Annemarie; Droomers, Mariël; Groenewegen, Peter P; Hardyns, Wim; Stronks, Karien

    2015-01-01

    The aim of this study was to examine whether changes over time in reported area crime and perceived area safety were related to self-rated general health and physical activity (PA), in order to provide support for a causal relationship between social safety and health. Additionally, we investigated whether social cohesion protects the residents against the negative impact of unsafe areas on health and PA. Multilevel logistic regression analyses were performed on Dutch survey data, including 47,926 respondents living in 2974 areas. An increase in area level unsafety feelings between 2009 and 2011 was associated with more people reporting poor general health in 2012 in that area, but was not related to PA. Changes in reported area crime were not related to either poor general health or PA. The social cohesion in the area did not modify the effect of changes in social safety on health and PA. The results suggest that tackling feelings of unsafety in an area might contribute to the better general health of the residents. Because changes in area social safety were not associated with PA, we found no leads that such health benefits were achieved through an increase in physical activity. PMID:25463916

  7. Built Environments and Active Living in Rural and Remote Areas: a Review of the Literature.

    PubMed

    Hansen, Anush Yousefian; Umstattd Meyer, M Renée; Lenardson, Jennifer D; Hartley, David

    2015-12-01

    Rural children and adults are more likely to have obesity than their urban counterparts even after adjustment for individual-level behaviors, suggesting that rural environments may promote obesity. The rural built environment may be an important area of research that can help us understand rural-urban disparities in obesity. The purpose of this review is to summarize the rural built environment and active living literature, and to address key issues, gaps, and observations in the field. A literature review was conducted in spring 2015 to identify research published from 2000 to 2015. Our review suggests that limited active living built environments in rural communities and unique rural barriers to physical activity may contribute to a higher prevalence of obesity compared to urban populations. More empirical research is needed to build the evidence-base for the association between rural built environments, active living, and obesity. School- and community-based policies that expand active living opportunities in rural areas should also be closely examined. PMID:26364307

  8. Preliminary results of systematic sampling of gas manifestations in geodynamically active areas of Greece

    NASA Astrophysics Data System (ADS)

    Daskalopoulou, Kyriaki; D'Alessandro, Walter; Calabrese, Sergio; Kyriakopoulos, Konstantinos

    2016-04-01

    Greece is located on a convergent plate boundary comprising the subduction of the African Plate beneath the Eurasian, while the Arabian plate approaches the Eurasian in a northwestward motion. It is considered to be one of the most tectonically active regions of Earth with a complex geodynamic setting, deriving from a long and complicated geological history. Due to this specific geological background, conditions for the formation of many thermal springs are favoured. In the past years, almost all the already known sites of degassing (fumaroles, soil gases, mofettes, gas bubbling in cold and thermal waters) located in the Hellenic area were sampled at least one time. Collected samples were analysed for their chemical (He, Ne, Ar, O2, N2, H2, H2S, CO, CH4 and CO2) and isotopic composition (He, C and N). Some of these sites have been selected for systematic sampling. Four of them have records longer than 10 years with tens of samplings also considering some literature data. Two of the sites are located in active volcanic areas (Santorini and Nisyros) while the other two are close to actively spreading graben structures with intense seismic activity (Gulf of Korinth and Sperchios basin). Results allowed to define long term background values and also some interesting variation related to seismic or volcanic activity.

  9. Changes in the exercise activation of diencephalic and brainstem cardiorespiratory areas after training.

    PubMed

    Ichiyama, Ronaldo M; Gilbert, Andrea B; Waldrop, Tony G; Iwamoto, Gary A

    2002-08-30

    The purpose of this study was to determine whether exercise training changes the extent or pattern of activation of areas in the central nervous system (CNS) involved in cardiorespiratory control. Rats that spontaneously trained on running wheels for 80-100 days were compared to rats that were not provided an opportunity to exercise. Selected brain regions including the hypothalamic and mesencephalic locomotor regions, and ventrolateral medulla were studied using c-Fos-like immunocytochemistry. A single test bout of exercise evoked significantly less activation as indicated by Fos labeling in the posterior (caudal) hypothalamic area, periaqueductal gray, nucleus of the tractus solitarius and the rostral ventrolateral medulla of the trained rats when compared to sedentary rats. These results are consistent with the concept that the nervous system changes its responses to a given level of exercise after training. These changes may also be related to perceived exertion. PMID:12176165

  10. Surveillance and maintenance activities of waste area groupings at Oak Ridge National Laboratory

    SciTech Connect

    Ford, M.K.; Holder, L. Jr.; Jones, R.G.

    1991-12-01

    Surveillance and maintenance (S M) of 75 sites were conductd by the Remedial Action Section for the Environmental Restoration Program for surplus facilities and sites contaminated with radioactive materials and/or hazardous chemicals. S M activities on these sites were conducted from the end of their operating life until final facility disposal or site stabilization. The objectives of the Waste Area Grouping S M Program are met by maintaining a program of routine S M as well as by implementing interim corrective maintenance when deemed necessary as a result of site surveillance. This report briefly presents this program's activities and includes tables indicating tank levels and dry well data for FY 1991.

  11. Alkali metal ionization detector

    DOEpatents

    Bauerle, James E.; Reed, William H.; Berkey, Edgar

    1978-01-01

    Variations in the conventional filament and collector electrodes of an alkali metal ionization detector, including the substitution of helical electrode configurations for either the conventional wire filament or flat plate collector; or, the substitution of a plurality of discrete filament electrodes providing an in situ capability for transferring from an operationally defective filament electrode to a previously unused filament electrode without removing the alkali metal ionization detector from the monitored environment. In particular, the helical collector arrangement which is coaxially disposed about the filament electrode, i.e. the thermal ionizer, provides an improved collection of positive ions developed by the filament electrode. The helical filament design, on the other hand, provides the advantage of an increased surface area for ionization of alkali metal-bearing species in a monitored gas environment as well as providing a relatively strong electric field for collecting the ions at the collector electrode about which the helical filament electrode is coaxially positioned. Alternatively, both the filament and collector electrodes can be helical. Furthermore, the operation of the conventional alkali metal ionization detector as a leak detector can be simplified as to cost and complexity, by operating the detector at a reduced collector potential while maintaining the sensitivity of the alkali metal ionization detector adequate for the relatively low concentration of alkali vapor and aerosol typically encountered in leak detection applications.

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

    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

  13. Areas activated during naturalistic reading comprehension overlap topological visual, auditory, and somatotomotor maps.

    PubMed

    Sood, Mariam R; Sereno, Martin I

    2016-08-01

    Cortical mapping techniques using fMRI have been instrumental in identifying the boundaries of topological (neighbor-preserving) maps in early sensory areas. The presence of topological maps beyond early sensory areas raises the possibility that they might play a significant role in other cognitive systems, and that topological mapping might help to delineate areas involved in higher cognitive processes. In this study, we combine surface-based visual, auditory, and somatomotor mapping methods with a naturalistic reading comprehension task in the same group of subjects to provide a qualitative and quantitative assessment of the cortical overlap between sensory-motor maps in all major sensory modalities, and reading processing regions. Our results suggest that cortical activation during naturalistic reading comprehension overlaps more extensively with topological sensory-motor maps than has been heretofore appreciated. Reading activation in regions adjacent to occipital lobe and inferior parietal lobe almost completely overlaps visual maps, whereas a significant portion of frontal activation for reading in dorsolateral and ventral prefrontal cortex overlaps both visual and auditory maps. Even classical language regions in superior temporal cortex are partially overlapped by topological visual and auditory maps. By contrast, the main overlap with somatomotor maps is restricted to a small region on the anterior bank of the central sulcus near the border between the face and hand representations of M-I. Hum Brain Mapp 37:2784-2810, 2016. © 2016 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc. PMID:27061771

  14. Areas activated during naturalistic reading comprehension overlap topological visual, auditory, and somatotomotor maps

    PubMed Central

    2016-01-01

    Abstract Cortical mapping techniques using fMRI have been instrumental in identifying the boundaries of topological (neighbor‐preserving) maps in early sensory areas. The presence of topological maps beyond early sensory areas raises the possibility that they might play a significant role in other cognitive systems, and that topological mapping might help to delineate areas involved in higher cognitive processes. In this study, we combine surface‐based visual, auditory, and somatomotor mapping methods with a naturalistic reading comprehension task in the same group of subjects to provide a qualitative and quantitative assessment of the cortical overlap between sensory‐motor maps in all major sensory modalities, and reading processing regions. Our results suggest that cortical activation during naturalistic reading comprehension overlaps more extensively with topological sensory‐motor maps than has been heretofore appreciated. Reading activation in regions adjacent to occipital lobe and inferior parietal lobe almost completely overlaps visual maps, whereas a significant portion of frontal activation for reading in dorsolateral and ventral prefrontal cortex overlaps both visual and auditory maps. Even classical language regions in superior temporal cortex are partially overlapped by topological visual and auditory maps. By contrast, the main overlap with somatomotor maps is restricted to a small region on the anterior bank of the central sulcus near the border between the face and hand representations of M‐I. Hum Brain Mapp 37:2784–2810, 2016. © 2016 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc. PMID:27061771

  15. Local field potential activity associated with temporal expectations in the macaque lateral intraparietal area.

    PubMed

    Premereur, Elsie; Vanduffel, Wim; Janssen, Peter

    2012-06-01

    Oscillatory brain activity is attracting increasing interest in cognitive neuroscience. Numerous EEG (magnetoencephalography) and local field potential (LFP) measurements have related cognitive functions to different types of brain oscillations, but the functional significance of these rhythms remains poorly understood. Despite its proven value, LFP activity has not been extensively tested in the macaque lateral intraparietal area (LIP), which has been implicated in a wide variety of cognitive control processes. We recorded action potentials and LFPs in area LIP during delayed eye movement tasks and during a passive fixation task, in which the time schedule was fixed so that temporal expectations about task-relevant cues could be formed. LFP responses in the gamma band discriminated reliably between saccade targets and distractors inside the receptive field (RF). Alpha and beta responses were much less strongly affected by the presence of a saccade target, however, but rose sharply in the waiting period before the go signal. Surprisingly, conditions without visual stimulation of the LIP-RF-evoked robust LFP responses in every frequency band--most prominently in those below 50 Hz--precisely time-locked to the expected time of stimulus onset in the RF. These results indicate that in area LIP, oscillations in the LFP, which reflect synaptic input and local network activity, are tightly coupled to the temporal expectation of task-relevant cues. PMID:22390466

  16. MS Detectors

    SciTech Connect

    Koppenaal, David W.; Barinaga, Charles J.; Denton, M Bonner B.; Sperline, Roger P.; Hieftje, Gary M.; Schilling, G. D.; Andrade, Francisco J.; Barnes IV., James H.

    2005-11-01

    Good eyesight is often taken for granted, a situation that everyone appreciates once vision begins to fade with age. New eyeglasses or contact lenses are traditional ways to improve vision, but recent new technology, i.e. LASIK laser eye surgery, provides a new and exciting means for marked vision restoration and improvement. In mass spectrometry, detectors are the 'eyes' of the MS instrument. These 'eyes' have also been taken for granted. New detectors and new technologies are likewise needed to correct, improve, and extend ion detection and hence, our 'chemical vision'. The purpose of this report is to review and assess current MS detector technology and to provide a glimpse towards future detector technologies. It is hoped that the report will also serve to motivate interest, prompt ideas, and inspire new visions for ion detection research.

  17. Active Travel by Built Environment and Lifecycle Stage: Case Study of Osaka Metropolitan Area

    PubMed Central

    Waygood, E. Owen D.; Sun, Yilin; Letarte, Laurence

    2015-01-01

    Active travel can contribute to physical activity achieved over a day. Previous studies have examined active travel associated with trips in various western countries, but few studies have examined this question for the Asian context. Japan has high levels of cycling, walking and public transport, similar to The Netherlands. Most studies have focused either on children or on adults separately, however, having children in a household will change the travel needs and wants of that household. Thus, here a household lifecycle stage approach is applied. Further, unlike many previous studies, the active travel related to public transport is included. Lastly, further to examining whether the built environment has an influence on the accumulation of active travel minutes, a binary logistic regression examines the built environment’s influence on the World Health Organization’s recommendations of physical activity. The findings suggest that there is a clear distinction between the urbanized centers and the surrounding towns and unurbanized areas. Further, active travel related to public transport trips is larger than pure walking trips. Females and children are more likely to achieve the WHO recommendations. Finally, car ownership is a strong negative influence. PMID:26694429

  18. Active Travel by Built Environment and Lifecycle Stage: Case Study of Osaka Metropolitan Area.

    PubMed

    Waygood, E Owen D; Sun, Yilin; Letarte, Laurence

    2015-12-01

    Active travel can contribute to physical activity achieved over a day. Previous studies have examined active travel associated with trips in various western countries, but few studies have examined this question for the Asian context. Japan has high levels of cycling, walking and public transport, similar to The Netherlands. Most studies have focused either on children or on adults separately, however, having children in a household will change the travel needs and wants of that household. Thus, here a household lifecycle stage approach is applied. Further, unlike many previous studies, the active travel related to public transport is included. Lastly, further to examining whether the built environment has an influence on the accumulation of active travel minutes, a binary logistic regression examines the built environment's influence on the World Health Organization's recommendations of physical activity. The findings suggest that there is a clear distinction between the urbanized centers and the surrounding towns and unurbanized areas. Further, active travel related to public transport trips is larger than pure walking trips. Females and children are more likely to achieve the WHO recommendations. Finally, car ownership is a strong negative influence. PMID:26694429

  19. Influence of vegetation spatial heterogeneity on soil enzyme activity in burned Mediterranean areas

    NASA Astrophysics Data System (ADS)

    Mayor, Á. G.; Goirán, S.; Bautista, S.

    2009-04-01

    Mediterranean ecosystems are commonly considered resilient to wildfires. However, depending on fire severity and recurrence, post-fire climatic conditions and plant community type, the recovery rate of the vegetation can greatly vary. Often, the post-fire vegetation cover remains low and sparsely distributed many years after the wildfire, which could have profound impacts on ecosystem functioning. In this work, we studied the influence of vegetation patchiness on soil enzyme activity (acid phosphatase, β-glucosidase and urease), at the patch and landscape scales, in degraded dry Mediterranean shrublands affected by wildfires. At the patch scale, we assessed the variation in soil enzyme between bare soils and vegetation patches. At the landscape scale, we studied the relationships between soil enzyme activity and various landscape metrics (total patch cover, average interpatch length, average patch width, and patch density). The study was conducted in 19 sites in the Valencia Region (eastern Spain), which had been affected by large wildfires in 1991. Site selection aimed at capturing a wide range of the variability of post-fire plant recovery rates in Mediterranean areas. The activities of the three enzymes were significantly higher in soils under the vegetation canopies than in adjacent bare areas, which we attributed to the effect of plants on the soil amount of both enzyme substrates and enzymes. The differences between bare and plant microsites were larger in the case of the acid phosphatase and less marked for urease. The activity of acid phosphatase was also higher under patches of resprouter species than under patches of seeder species, probably due to the faster post-fire recovery and older age of resprouter patches in fire-prone ecosystems. Soil enzyme activities of β-glucosidase and urease in both bare soils and vegetation patches showed no relationships with any of the landscape metrics analysed. However, the activity of acid phosphatase increased

  20. Oxytocin activation of neurons in ventral tegmental area and interfascicular nucleus of mouse midbrain.

    PubMed

    Tang, Yamei; Chen, Zhiheng; Tao, Huai; Li, Cunyan; Zhang, Xianghui; Tang, Aiguo; Liu, Yong

    2014-02-01

    Oxytocin (OT) was reported to affect cognitive and emotional behavior by action in ventral tegmental area (VTA) and other brain areas. However, it is still unclear how OT activates VTA and related midline nucleus. Here, using patch-clamp recording, we studied the effects of OT on neuron activity in VTA and interfascicular nucleus (IF). OT dose-dependently and selectively excited small neurons located in medial VTA and the majority of IF neurons but not large neurons in lateral VTA. We found the hyperpolarization-activated current (I(h)) and the membrane capacitance of OT-sensitive neuron were significantly smaller than those of OT-insensitive neurons. The action potential width of OT-sensitive neurons was about half that of OT-insensitive neurons. The OT effect was blocked by the OT receptor antagonist atosiban and WAY-267464 but not by tetrodotoxin, suggesting a direct postsynaptic activation of OT receptors. In addition, the phospholipase C (PLC) inhibitor U73122 antagonized the depolarization by OT. Both the nonselective cation channel (NSCC) antagonist SKF96365 and the Na(+)-Ca(2+) exchanger (NCX) blocker SN-6 attenuated OT effects. These results suggested that the PLC signaling pathway coupling to NSCC and NCX contributes to the OT-mediated activation of neurons in medial VTA and IF. Taken together, our results indicate OT directly acted on medial VTA and especially IF neurons to activate NSCC and NCX via PLC. The direct activation by OT of midbrain neurons may be one mechanism underlying OT effects on social behavior. PMID:24148809

  1. The development and test of multi-anode microchannel array detector systems. Part 2: Soft X-ray detectors

    NASA Technical Reports Server (NTRS)

    Timothy, J. G.

    1986-01-01

    Multi-Anode Microchannel Array (MAMA) detector systems with formats of 256 x 1024 pixels and active areas of 6 x 26 square mm are now under evaluation at visible, ultraviolet and soft x-ray wavelengths. Very-large-format versions of the MAMA detectors with formats of 2048 x 2048 pixels and active areas of 52 x 52 square mm are under development for use in the NASA Goddard Space Flight Center's Space Telescope Imaging Spectrograph (STIS). Open-structure versions of these detectors with CsI photocathodes can provide a high-resolution imaging capability at extreme ultraviolet (EUV) and soft x-ray wavelengths and can deliver a maximum count rate from each array in excess of 1 million counts s-1. In addition, these detector systems have the unique capability to determine the arrival time of a detected photon to an accuracy of 100 ns or better. The construction, mode-of-operation and performance characteristics of the MAMA detectors are described and the program for the development of the very-large-format detectors is outlined.

  2. Neutron and X-ray Detectors

    SciTech Connect

    Carini, Gabriella; Denes, Peter; Gruener, Sol; Lessner, Elianne

    2012-08-01

    The Basic Energy Sciences (BES) X-ray and neutron user facilities attract more than 12,000 researchers each year to perform cutting-edge science at these state-of-the-art sources. While impressive breakthroughs in X-ray and neutron sources give us the powerful illumination needed to peer into the nano- to mesoscale world, a stumbling block continues to be the distinct lag in detector development, which is slowing progress toward data collection and analysis. Urgently needed detector improvements would reveal chemical composition and bonding in 3-D and in real time, allow researchers to watch “movies” of essential life processes as they happen, and make much more efficient use of every X-ray and neutron produced by the source The immense scientific potential that will come from better detectors has triggered worldwide activity in this area. Europe in particular has made impressive strides, outpacing the United States on several fronts. Maintaining a vital U.S. leadership in this key research endeavor will require targeted investments in detector R&D and infrastructure. To clarify the gap between detector development and source advances, and to identify opportunities to maximize the scientific impact of BES user facilities, a workshop on Neutron and X-ray Detectors was held August 1-3, 2012, in Gaithersburg, Maryland. Participants from universities, national laboratories, and commercial organizations from the United States and around the globe participated in plenary sessions, breakout groups, and joint open-discussion summary sessions. Sources have become immensely more powerful and are now brighter (more particles focused onto the sample per second) and more precise (higher spatial, spectral, and temporal resolution). To fully utilize these source advances, detectors must become faster, more efficient, and more discriminating. In supporting the mission of today’s cutting-edge neutron and X-ray sources, the workshop identified six detector research challenges

  3. Seismic intrusion detector system

    DOEpatents

    Hawk, Hervey L.; Hawley, James G.; Portlock, John M.; Scheibner, James E.

    1976-01-01

    A system for monitoring man-associated seismic movements within a control area including a geophone for generating an electrical signal in response to seismic movement, a bandpass amplifier and threshold detector for eliminating unwanted signals, pulse counting system for counting and storing the number of seismic movements within the area, and a monitoring system operable on command having a variable frequency oscillator generating an audio frequency signal proportional to the number of said seismic movements.

  4. Geology is the Key to Explain Igneous Activity in the Mediterranean Area

    NASA Astrophysics Data System (ADS)

    Lustrino, M.

    2014-12-01

    Igneous activity in tectonically complex areas can be interpreted in many different ways, producing completely different petrogenetic models. Processes such as oceanic and continental subduction, lithospheric delamination, changes in subduction polarity, slab break-off and mantle plumes have all been advocated as causes for changes in plate boundaries and magma production, including rate and temporal distribution, in the circum-Mediterranean area. This region thus provides a natural laboratory to investigate a range of geodynamic and magmatic processes. Although many petrologic and tectonic models have been proposed, a number of highly controversial questions still remain. No consensus has yet been reached about the capacity of plate-tectonic processes to explain the origin and style of the magmatism. Similarly, there is still not consensus on the ability of geochemical and petrological arguments to reveal the geodynamic evolution of the area. The wide range of chemical and mineralogical magma compositions produced within and around the Mediterranean, from carbonatites to strongly silica-undersaturated silico-carbonatites and melilitites to strongly silica-oversaturated rhyolites, complicate models and usually require a large number of unconstrained assumptions. Can the calcalkaline-sodic alkaline transition be related to any common petrogenetic point? Is igneous activity plate-tectonic- (top-down) or deep-mantle-controlled (bottom-up)? Do the rare carbonatites and carbonate-rich igneous rocks derive from the deep mantle or a normal, CO2-bearing upper mantle? Do ultrapotassic compositions require continental subduction? Understanding chemically complex magmas emplaced in tectonically complex areas require open minds, and avoiding dogma and assumptions. Studying the geology and shallow dynamics, not speculating about the deep lower mantle, is the key to understanding the igneous activity.

  5. Light detectors for beauty physics

    NASA Astrophysics Data System (ADS)

    DeSalvo, R.

    1996-12-01

    Cherenkov light is used to identify beauty mesons in high energy interactions in an increasing number of experiments. Speed and pixel dimension requirements are generating a revival of the vacuum light detectors as the active component of Cherenkov light detectors in the new high luminosity and high background experiments. The insensitivity to magnetic fields of the most modern vacuum light detectors also helps making these devices more competitive.

  6. Performance studies of a Micromegas detector with a pad readout geometry

    NASA Astrophysics Data System (ADS)

    Düdder, A.; Lin, T.-H.; Neuhaus, F.; Schott, M.; Valderanis, C.

    2016-07-01

    The results of several performance studies of two prototype Micromegas pad detectors with two different coupling implementations between the resistive and the readout layer are presented. Both prototype detectors have an active area of 10 × 10cm2 and comprise 500 pads with a size of 5 × 4mm2. The first detector has a capacitive coupling between the resistive and the readout layer, as it is well known from Micromegas detectors with a strip readout. The second detector implements a resistive coupling between each readout pad and the resistive layer on top of it with a resistivity of 5 MΩ. In particular, the size of reconstructed charge clusters in both detector types is discussed and compared here for different drift- and amplification voltages.

  7. Photon detectors with gaseous amplification

    SciTech Connect

    Va`vra, J.

    1996-08-01

    Gaseous photon detectors, including very large 4{pi}-devices such as those incorporated in SLD and DELPHI, are finally delivering physics after many years of hard work. Photon detectors are among the most difficult devices used in physics experiments, because they must achieve high efficiency for photon transport and for the detection of single photoelectrons. Among detector builders, there is hardly anybody who did not make mistakes in this area, and who does not have a healthy respect for the problems involved. This point is stressed in this paper, and it is suggested that only a very small operating phase space is available for running gaseous photon detectors in a very large system with good efficiency and few problems. In this paper the authors discuss what was done correctly or incorrectly in first generation photon detectors, and what would be their recommendations for second generation detectors. 56 refs., 11 figs.

  8. Support chemistry, surface area, and preparation effects on sulfided NiMo catalyst activity

    SciTech Connect

    Gardner, T.J.; McLaughlin, L.I.; Sandoval, R.S.

    1996-06-01

    Hydrous Metal Oxides (HMOs) are chemically synthesized materials which contain a homogeneous distribution of ion exchangeable alkali cations that provide charge compensation to the metal-oxygen framework. In terms of the major types of inorganic ion exchangers defined by Clearfield, these amorphous HMO materials are similar to both hydrous oxides and layered oxide ion exchangers (e.g., alkali metal titanates). For catalyst applications, the HMO material serves as an ion exchangeable support which facilitates the uniform incorporation of catalyst precursor species. Following catalyst precursor incorporation, an activation step is required to convert the catalyst precursor to the desired active phase. Considerable process development activities at Sandia National Laboratories related to HMO materials have resulted in bulk hydrous titanium oxide (HTO)- and silica-doped hydrous titanium oxide (HTO:Si)-supported NiMo catalysts that are more active in model reactions which simulate direct coal liquefaction (e.g., pyrene hydrogenation) than commercial {gamma}-Al{sub 2}O{sub 3}-supported NiMo catalysts. However, a fundamental explanation does not exist for the enhanced activity of these novel catalyst materials; possible reasons include fundamental differences in support chemistry relative to commercial oxides, high surface area, or catalyst preparation effects (ion exchange vs. incipient wetness impregnation techniques). The goals of this paper are to identify the key factors which control sulfided NiMo catalyst activity, including those characteristics of HTO- and HTO:Si-supported NiMo catalysts which uniquely set them apart from conventional oxide supports.

  9. Physical Activity, Sedentary Behavior and Substance Use among Adolescents in Slovenian Urban Area

    PubMed Central

    LESJAK, Vesna; STANOJEVIĆ-JERKOVIĆ, Olivera

    2015-01-01

    Background Studies of the relationship between leisure time physical activity, sedentary behaviour and substance use among adolescents report contradictory results. The aim of our study was to examine the association between self-reported leisure time physical activity, sedentary behaviour and alcohol, tobacco and cannabis use among adolescents in Slovenia. Methods Subjects consisted of 822 school children aged from 14 to 16 years, living in urban area of Ljubljana and Maribor. The data was collected using the EURO URHIS 2 survey. Logistic regressions were conducted to assess the correlation between the independent variables of physical activity; time spent watching television and using the computer, and each of the five substance use dependent variables. Results Frequency of daily smoking was significantly associated with leisure time physical activity, while alcohol and cannabis use were not. Watching TV ≥ 2 hours per day was associated with heavy episodic drinking in the past month, no associations were found for smoking and cannabis use. Using the computer ≥ 2 hours per day was positively associated with daily smoking, drinking alcohol in the past month, heavy episodic drinking in the past month and ever being intoxicated, while cannabis use was not. Conclusions These findings suggest that leisure time physical activity is associated with daily cigarette smoking, and leisure time sedentary behaviour is associated with alcohol and tobacco use among adolescents. The results of our study show the need for the formation of suitable preventive measures concerning reduced sitting time as well as leisure time physical activity targeted to adolescents.

  10. Cosmic ray detectors

    NASA Technical Reports Server (NTRS)

    Gregory, John C.

    1987-01-01

    Work on the MSFC emulsion laboratory microscopes in which mechanical modifications previously made were verified is reviewed, as is a design study of a large area hybrid electronic/emulsion chamber balloon flight detector system. This design is built upon the experience obtained with the highly successful MSFC/UAH hybrid instrument flown by the JACEE consortium. The design included overall system design and specification, design and fabrication of a prototype large light diffusion for Cerenkov charge detector or scintillator, design of a multiwire proportional counter array and design of the gondola or flight support system.

  11. 50 μm pixel pitch wafer-scale CMOS active pixel sensor x-ray detector for digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Zhao, C.; Konstantinidis, A. C.; Zheng, Y.; Anaxagoras, T.; Speller, R. D.; Kanicki, J.

    2015-12-01

    Wafer-scale CMOS active pixel sensors (APSs) have been developed recently for x-ray imaging applications. The small pixel pitch and low noise are very promising properties for medical imaging applications such as digital breast tomosynthesis (DBT). In this work, we evaluated experimentally and through modeling the imaging properties of a 50 μm pixel pitch CMOS APS x-ray detector named DynAMITe (Dynamic Range Adjustable for Medical Imaging Technology). A modified cascaded system model was developed for CMOS APS x-ray detectors by taking into account the device nonlinear signal and noise properties. The imaging properties such as modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE) were extracted from both measurements and the nonlinear cascaded system analysis. The results show that the DynAMITe x-ray detector achieves a high spatial resolution of 10 mm-1 and a DQE of around 0.5 at spatial frequencies  <1 mm-1. In addition, the modeling results were used to calculate the image signal-to-noise ratio (SNRi) of microcalcifications at various mean glandular dose (MGD). For an average breast (5 cm thickness, 50% glandular fraction), 165 μm microcalcifications can be distinguished at a MGD of 27% lower than the clinical value (~1.3 mGy). To detect 100 μm microcalcifications, further optimizations of the CMOS APS x-ray detector, image aquisition geometry and image reconstruction techniques should be considered.

  12. 50 μm pixel pitch wafer-scale CMOS active pixel sensor x-ray detector for digital breast tomosynthesis.

    PubMed

    Zhao, C; Konstantinidis, A C; Zheng, Y; Anaxagoras, T; Speller, R D; Kanicki, J

    2015-12-01

    Wafer-scale CMOS active pixel sensors (APSs) have been developed recently for x-ray imaging applications. The small pixel pitch and low noise are very promising properties for medical imaging applications such as digital breast tomosynthesis (DBT). In this work, we evaluated experimentally and through modeling the imaging properties of a 50 μm pixel pitch CMOS APS x-ray detector named DynAMITe (Dynamic Range Adjustable for Medical Imaging Technology). A modified cascaded system model was developed for CMOS APS x-ray detectors by taking into account the device nonlinear signal and noise properties. The imaging properties such as modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE) were extracted from both measurements and the nonlinear cascaded system analysis. The results show that the DynAMITe x-ray detector achieves a high spatial resolution of 10 mm(-1) and a DQE of around 0.5 at spatial frequencies  <1 mm(-1). In addition, the modeling results were used to calculate the image signal-to-noise ratio (SNRi) of microcalcifications at various mean glandular dose (MGD). For an average breast (5 cm thickness, 50% glandular fraction), 165 μm microcalcifications can be distinguished at a MGD of 27% lower than the clinical value (~1.3 mGy). To detect 100 μm microcalcifications, further optimizations of the CMOS APS x-ray detector, image aquisition geometry and image reconstruction techniques should be considered. PMID:26540090

  13. Characterizing, controlling, and correcting distortions in the COS FUV detector

    NASA Astrophysics Data System (ADS)

    Sahnow, David J.; Becker, George D.; Debes, John H.; Ely, Justin; Lockwood, Sean A.; Massa, Derck; Oliveira, Cristina M.; Penton, Steven V.; Proffitt, Charles; Roman-Duval, Julia; Sana, Hugues; Sonnentrucker, Paule; Taylor, Joanna

    2015-09-01

    The Far Ultraviolet (FUV) detector on the Cosmic Origins Spectrograph (COS) of the Hubble Space Telescope (HST) is subject to a variety of distortions due to its analog nature. Thermal variations of the detector and electronics stretch and shift the active area. Geometric distortions on a range of spatial scales warp the two-dimensional spectral image. Changes due to detector walk - the dependence of detected position on pulse height - add distortions that change as a function of time. The calcos calibration pipeline includes corrections for each of these effects in the calibrated spectra, but these are imperfect, and they do not help with the target acquisition process, which uses raw detector coordinates. We discuss these distortions and their effect on the data, our attempts to mitigate them, the current pipeline corrections and their success at removing the effects, and possible modifications to improve the data quality in the future.

  14. Dynamic characteristics of an active coastal spreading area using ambient noise measurements—Anchor Bay, Malta

    NASA Astrophysics Data System (ADS)

    Galea, Pauline; D'Amico, Sebastiano; Farrugia, Daniela

    2014-11-01

    Anchor Bay and surrounding regions are located on the northwest coast of the island of Malta, Central Mediterranean. The area is characterized by a coastal cliff environment having an outcropping layer of hard coralline limestone (UCL) resting on a thick (up to 50 m) layer of clays and marls (Blue Clay, BC). This configuration gives rise to coastal instability effects, in particular lateral spreading phenomena and rock falls. Previous and ongoing studies have identified both lateral spreading rates and vertical motions of several millimetres per year. The area is an interesting natural laboratory as coastal detachment processes in a number of different stages can be identified and are easily accessible. We investigate the site dynamic characteristics of this study area by recording ambient noise time-series at more than 30 points, over an area of 0.07 km2, using a portable three-component seismograph. The time-series are processed to give both horizontal-to-vertical spectral ratio graphs (H/V) as well as frequency-dependent polarisation analysis. The H/V graphs illustrate and quantify aspects of site resonance effects due both to underlying geology as well as to mechanical resonance of partly or wholly detached blocks. The polarization diagrams indicate the degree of linearity and predominant directions of vibrational effects. H/V curves closer to the cliff edge show complex responses at higher frequencies, characteristic of the dynamic behaviour of individual detached blocks. Particle motion associated with the higher frequencies shows strongly directional polarization and a high degree of linearity at well-defined frequencies, indicative of normal-mode vibration. The stable plateau areas, on the other hand, show simple, single-peak H/V curves representative of the underlying stratification and no predominant polarization direction. These results, which will be compared with those from other experiments in the area, have important implications for the

  15. Knowing good from bad: differential activation of human cortical areas by positive and negative outcomes.

    PubMed

    Nieuwenhuis, Sander; Slagter, Heleen A; von Geusau, Niels J Alting; Heslenfeld, Dirk J; Holroyd, Clay B

    2005-06-01

    Previous research has identified a component of the event-related brain potential (ERP), the feedback-related negativity, that is elicited by feedback stimuli associated with unfavourable outcomes. In the present research we used event-related functional magnetic resonance imaging (fMRI) and electroencephalographic (EEG) recordings to test the common hypothesis that this component is generated in the caudal anterior cingulate cortex. The EEG results indicated that our paradigm, a time estimation task with trial-to-trial performance feedback, elicited a large feedback-related negativity (FRN). Nevertheless, the fMRI results did not reveal any area in the caudal anterior cingulate cortex that was differentially activated by positive and negative performance feedback, casting doubt on the notion that the FRN is generated in this brain region. In contrast, we found a number of brain areas outside the posterior medial frontal cortex that were activated more strongly by positive feedback than by negative feedback. These included areas in the rostral anterior cingulate cortex, posterior cingulate cortex, right superior frontal gyrus, and striatum. An anatomically constrained source model assuming equivalent dipole generators in the rostral anterior cingulate, posterior cingulate, and right superior frontal gyrus produced a simulated scalp distribution that corresponded closely to the observed scalp distribution of the FRN. These results support a new hypothesis regarding the neural generators of the FRN, and have important implications for the use of this component as an electrophysiological index of performance monitoring and reward processing. PMID:15978024

  16. Exploring Bikeability in a Suburban Metropolitan Area Using the Active Commuting Route Environment Scale (ACRES)

    PubMed Central

    Wahlgren, Lina; Schantz, Peter

    2014-01-01

    Background and Aim: Commuting by bicycle could contribute to public health, and route environments may influence this behaviour. Therefore, the aim of this study is to assess the potential associations between appraisals of the overall route environment as hindering or stimulating for bicycle commuting, with both perceptions of commuting route environmental factors in a suburban area and background factors. Methods: The Active Commuting Route Environment Scale (ACRES) was used for the assessment of bicycle commuters’ perceptions and appraisals of their route environments in the suburban parts of Greater Stockholm, Sweden. A simultaneous multiple regression analysis was used to assess the relationship between the outcome variable whether the overall route environment hinders or stimulates bicycle commuting and environmental factors (e.g., exhaust fumes, speeds of motor vehicles, greenery), as well as background factors (sex, age, education, income) as predictor variables. Results and Conclusions: The results indicate that in suburban areas, the factors aesthetics, greenery and bicycle paths seem to be, independently of each other, stimulating factors for bicycle commuting. On the other hand, flows of motor vehicles, noise, and low “directness” of the route seem to be hindering factors. A comparison of these results with those obtained from an inner urban area points to the importance of studying different types of built-up areas separately. PMID:25153462

  17. Study of the directionality of cosmic muons using the INO-ICAL prototype detector

    NASA Astrophysics Data System (ADS)

    Majumder, G.; Mondal, N. K.; Pal, S.; Samuel, D.; Satyanarayana, B.

    2014-01-01

    The India-based Neutrino Observatory (INO) collaboration is planning to build a magnetised Iron-CALorimeter detector (ICAL) to study atmospheric neutrino oscillations with high precision. The ICAL adopts a 50 kton iron target and about 28 800 Resistive Plate Chambers (RPC) of 2×2 m2 in area as active detector elements. As part of its R&D programme, a prototype detector stack composed of 12 layers of glass RPCs of 1×1 m2 in area has been set up at the Tata Institute of Fundamental Research (TIFR) to study the detector parameters using cosmic muons. We present here a study of the capability of this prototype detector to distinguish between up-going and down-going muons.

  18. Blockade of ENaCs by Amiloride Induces c-Fos Activation of the Area Postrema

    PubMed Central

    Miller, Rebecca L.; Denny, George O.; Knuepfer, Mark M.; Kleyman, Thomas R.; Jackson, Edwin K.; Salkoff, Lawrence B.; Loewy, Arthur D.

    2015-01-01

    Epithelial sodium channels (ENaCs) are strongly expressed in the circumventricular organs (CVOs), and these structures may play an important role in sensing plasma sodium levels. Here, the potent ENaC blocker amiloride was injected intraperitoneally in rats and 2 hours later, the c-Fos activation pattern in the CVOs was studied. Amiloride elicited dose-related activation in the area postrema (AP) but only ~10% of the rats showed c-Fos activity in the organum vasculosum of the lamina terminalis (OVLT) and subfornical organ (SFO). Tyrosine hydroxylase-immunoreactive (catecholamine) AP neurons were activated, but tryptophan hydroxylase-immunoreactive (serotonin) neurons were unaffected. The AP projects to FoxP2-expressing neurons in the dorsolateral pons which include the pre-locus coeruleus nucleus and external lateral part of the parabrachial nucleus; both cell groups were c-Fos activated following systemic injections of amiloride. In contrast, another AP projection target - the aldosterone-sensitive neurons of the nucleus tractus solitarius which express the enzyme 11-β-hydroxysteriod dehydrogenase type 2 (HSD2) were not activated. As shown here, plasma concentrations of amiloride used in these experiments were near or below the IC50 level for ENaCs. Amiloride did not induce changes in blood pressure, heart rate, or regional vascular resistance, so sensory feedback from the cardiovascular system was probably not a causal factor for the c-Fos activity seen in the CVOs. In summary, amiloride may have a dual effect on sodium homeostasis causing a loss of sodium via the kidney and inhibiting sodium appetite by activating the central satiety pathway arising from the AP. PMID:25557402

  19. Pyroelectric detectors

    NASA Technical Reports Server (NTRS)

    Haller, Eugene E.; Beeman, Jeffrey; Hansen, William L.; Hubbard, G. Scott; Mcmurray, Robert E., Jr.

    1990-01-01

    The multi-agency, long-term Global Change programs, and specifically NASA's Earth Observing system, will require some new and advanced photon detector technology which must be specifically tailored for long-term stability, broad spectral range, cooling constraints, and other parameters. Whereas MCT and GaAs alloy based photovoltaic detectors and detector arrays reach most impressive results to wavelengths as long as 12 microns when cooled to below 70 K, other materials, such as ferroelectrics and pyroelectrics, appear to offer special opportunities beyond 12 microns and above 70 K. These materials have found very broad use in a wide variety of room temperature applications. Little is known about these classes of materials at sub-room temperatures and no photon detector results have been reported. From the limited information available, researchers conclude that the room temperature values of D asterisk greater than or equal to 10(exp 9) cm Hz(exp 1/2)/W may be improved by one to two orders of magnitude upon cooling to temperatures around 70 K. Improvements of up to one order of magnitude appear feasible for temperatures achievable by passive cooling. The flat detector response over a wavelength range reaching from the visible to beyond 50 microns, which is an intrinsic advantage of bolometric devices, makes for easy calibration. The fact that these materials have been developed for reduced temperature applications makes ferro- and pyroelectric materials most attractive candidates for serious exploration.

  20. Towards an optimum design of a P-MOS radiation detector for use in high-energy medical photon beams and neutron facilities: analysis of activation materials.

    PubMed

    Price, Robert A

    2005-01-01

    The behaviour of packaged and unpackaged ESAPMOS4 RadFET radiation detectors (NMRC Cork, Ireland) was investigated when used in the mixed photon and neutron environment of a medical linear accelerator operating above the nucleon separation energy and in a 14 MeV neutron field provided by a D-T generator. Within the uncertainty of the experimental set-up (4% at 95% confidence level) the unpackaged device was found to have essentially zero activation dose-burden whereas the packaged device exhibits a considerable degree of post irradiation absorbed dose due to deactivation radiation. PMID:16381751