Sample records for photodiode array detectors

  1. Photon counting photodiode array detector for far ultraviolet (FUV) astronomy

    NASA Technical Reports Server (NTRS)

    Hartig, G. F.; Moos, H. W.; Pembroke, R.; Bowers, C.

    1982-01-01

    A compact, stable, single-stage intensified photodiode array detector designed for photon-counting, far ultraviolet astronomy applications employs a saturable, 'C'-type MCP (Galileo S. MCP 25-25) to produce high gain pulses with a narrowly peaked pulse height distribution. The P-20 output phosphor exhibits a very short decay time, due to the high current density of the electron pulses. This intensifier is being coupled to a self-scanning linear photodiode array which has a fiber optic input window which allows direct, rigid mechanical coupling with minimal light loss. The array was scanned at a 250 KHz pixel rate. The detector exhibits more than adequate signal-to-noise ratio for pulse counting and event location. Previously announced in STAR as N82-19118

  2. Self-scanned photodiode array - A multichannel spectrometric detector

    Microsoft Academic Search

    Yair Talmi; R. W. Simpson

    1980-01-01

    The paper reports the spectrometric performance of a self-scanned linear photodiode array (SPD) designed as a parallel spectrometric detector. The device uses diodes with 2.5-mm apertures and an aspect ratio of 100:1, which corresponds to the typical aspect ratio of a conventional polychromator slit. The parameters discussed include spectral and temporal response, blooming, geometric accuracy, noise sources, dynamic range, signal

  3. Detector telescope array: silicon--CsI(Tl)--photodiode

    NASA Astrophysics Data System (ADS)

    Norbeck, E.; Yang, L. B.; Pogodin, P.; Ingram, F. D.

    1999-10-01

    A closely packed array of 60 telescopes was developed for use at forward angles in the 4? Array at the National Superconducting Cyclotron Laboratory at Michigan State University. The telescopes resolve isotopes and cover nearly 100% of the solid angle assigned to the array. These requirements and limitations of space and funding resulted in a number of novel features, some of which will be useful in other applications. These features include: photodiodes of arbitrary shape with no frame around the edge, replacement of aluminized Mylar with aluminum leaf, an inexpensive silicon diode leakage current monitor that presents a graph of leakage current vs detector number, and a low noise but inexpensive preamplifier chip. Experience with the array showed that compounds in the outer insulation layer of some types of coax cable can seriously contaminate a vacuum system. The use of computer aided design and computer controlled machine tools reduced the cost of the structural parts by orders of magnitude.

  4. An intensified photodiode array detector for space applications

    NASA Technical Reports Server (NTRS)

    Long, K. S.; Bowers, C. W.; Tennyson, P. D.; Davidsen, A. F.

    1985-01-01

    The Hopkins Ultraviolet Telescope (HUT) is a general purpose moderate resolution spectrograph which is now being constructed for launch on the Space Shuttle. The instrument contains a Rowland spectrograph, which is located at the prime focus of a 0.9-m f/2 parabola. A description is given of the progress which has been made in the development of a flight detector for HUT. The detector developed is an intensified photodiode array. The image intensifier part of the detector contains two 25-mm 80:1, 12-micron pore microchannel plates (PCPs). A thin layer of CsI deposited on the front surface of the first microchannel plate has the objective to increase the quantum efficiency of the detector below 1850 A. The detector system utilizes a spectrometer processor (SP) which is based upon a bit-sliced microprocessor. The current status of the HUT detector system is discussed, and aspects of performance are evaluated. It is felt that the developed system will meet or exceed the design requirements.

  5. Signal and noise characteristics induced by unattenuated x rays from a scintillator in indirect-conversion CMOS photodiode array detectors

    E-print Network

    Cunningham, Ian

    -conversion CMOS photodiode array detectors Seung Man Yun1 , Chang Hwy Lim1 , Ho Kyung Kim1,* , Thorsten Graeve2 by the direct x-rays in an indirect-conversion CMOS photodiode array detector. In order to isolate the signal show the direct x-ray is very harmful to the detector performances, such noise power spectrum (NPS

  6. An LSO BLOCK detector for PET using an avalanche photodiode array

    Microsoft Academic Search

    M. E. Casey; H. Dautet; D. Waechter; R. Lecomte; L. Eriksson; M. Schmand

    1998-01-01

    A Block detector, consisting of a four by four array of lutetium oxyorthosilicate (LSO) scintillator crystals coupled to a two by two avalanche photodiode (APD) array was built and tested. The detector block was 8.5 by 8.5 by 10 millimeters so that the crystals were on 2.13 millimeter centers. The APD array has an active area of approximately 9 by

  7. Intensified silicon photodiode array detector linearity Application to coherent anti-Stokes Raman spectroscopy

    NASA Technical Reports Server (NTRS)

    Antcliff, R. R.; Hillard, M. E.; Jarrett, O., Jr.

    1984-01-01

    The linearity of an intensified silicon photodiode array multichannel detector is studied with coherent anti-Stokes Raman and other similar signals. Studies with diffuse and focused (spherically and cylindrically) signals resolved apparent saturation problems which limit the dynamic range of the detector. In addition, it has been shown that there is no short-range wavelength (473-532-nm) dependence on this saturation. Theoretical explanations for these phenomena are also included.

  8. A photon-counting photodiode array detector for far ultraviolet (FUV) astronomy

    NASA Astrophysics Data System (ADS)

    Hartig, G. F.; Moos, H. W.; Pembroke, R.; Bowers, C.

    1982-10-01

    A compact, stable, single-stage intensified photodiode array detector designed for photon-counting, far ultraviolet astronomy applications employs a saturable, 'C'-type MCP (Galileo S. MCP 25-25) to produce high gain pulses with a narrowly peaked pulse height distribution. The P-20 output phosphor exhibits a very short decay time, due to the high current density of the electron pulses. This intensifier is being coupled to a self-scanning linear photodiode array which has a fiber optic input window which allows direct, rigid mechanical coupling with minimal light loss. The array was scanned at a 250 KHz pixel rate. The detector exhibits more than adequate signal-to-noise ratio for pulse counting and event location.

  9. A photon-counting photodiode array detector for far ultraviolet (FUV) astronomy

    NASA Technical Reports Server (NTRS)

    Hartig, G. F.; Moos, H. W.; Pembroke, R.; Bowers, C.

    1982-01-01

    A compact, stable, single-stage intensified photodiode array detector designed for photon-counting, far ultraviolet astronomy applications employs a saturable, 'C'-type MCP (Galileo S. MCP 25-25) to produce high gain pulses with a narrowly peaked pulse height distribution. The P-20 output phosphor exhibits a very short decay time, due to the high current density of the electron pulses. This intensifier is being coupled to a self-scanning linear photodiode array which has a fiber optic input window which allows direct, rigid mechanical coupling with minimal light loss. The array was scanned at a 250 KHz pixel rate. The detector exhibits more than adequate signal-to-noise ratio for pulse counting and event location.

  10. Performance of a PET detector module utilizing an array of silicon photodiodes to identify the crystal of interaction

    SciTech Connect

    Moses, W.W.; Derenzo, S.E. (Lawrence Berkeley Lab., CA (United States)); Nutt, R.; Digby, W.M.; Williams, C.W.; Andreaco, M. (CTI, Inc., Knoxville, TN (United States))

    1992-11-01

    We present initial performance results for a new multi-layer PET detector module consisting of an array of 3 mm square by 30 mm deep BGO crystals coupled on one end to a single photomultiplier tube and on the opposite end to an array of 3 mm square silicon photodiodes. The photomultiplier tube provides an accurate timing pulse and energy discrimination for the all the crystals in the module, while the silicon photodiodes identify the crystal of interaction. When a single BGO crystal at +25[degree]C is excited with 511 key photons, we measure a photodiode signal centered at 700 electrons (e[sup [minus

  11. Characterization and quality control of avalanche photodiode arrays for the Clear-PEM detector modules

    NASA Astrophysics Data System (ADS)

    Abreu, Concei玢o; Amaral, Pedro; Carri鏾, Bruno; Ferreira, Miguel; Luyten, Joan; Moura, Rui; Ortig鉶, Catarina; Rato, Pedro; Varela, Jo鉶

    2007-06-01

    Clear-PEM is a Positron Emission Mammography (PEM) prototype being developed in the framework of the Crystal Clear Collaboration at CERN. This device is a dedicated PET camera for mammography, based on LYSO:Ce scintillator crystals, Avalanche PhotoDiodes (APD) and a fast, low-noise electronics readout system, designed to examine both the breast and the axillary lymph node areas, and aiming at the detection of tumors down to 2 mm in diameter. The prototype has two planar detector heads, each composed of 96 detector modules. The Clear-PEM detector module is composed of a matrix of 32 identical 2󫎾0 mm 3 LYSO:Ce crystals read at both ends by Hamamatsu S8550 APD arrays (48) for Depth-of-Interaction (DoI) capability. The APD arrays were characterized by the measurement of gain and dark current as a function of bias voltage, under controlled temperature conditions. Two independent setups were used. The full set of 398 APD arrays followed a well-defined quality control (QC) protocol, aiming at the rejection of arrays not complying within defined specifications. From a total of 398 arrays, only 2 (0.5%) were rejected, reassuring the trust in these detectors for prototype assembly and future developments.

  12. Nonlinearity and image persistence of P-20 phosphor-based intensified photodiode array detectors used in CARS spectroscopy

    Microsoft Academic Search

    D. R. Snelling; G. J. Smallwood; R. A. Sawchuk

    1989-01-01

    Several self-scanning photodiode arrays (IPDA) used for CARS spectroscopy are shown to exhibit a greater image persistence than has generally been realized, and to exhibit a falloff in sensitivity that is logarithmic with decreasing output signal. These effects are attributed to the P-20 phosphor based intensifiers used in the IPDAs and are probably generic to all such detectors. A strategy

  13. Performance of a PET detector module utilizing an array of silicon photodiodes to identify the crystal of interaction

    SciTech Connect

    Moses, W.W.; Derenzo, S.E. [Lawrence Berkeley Lab., CA (United States); Nutt, R.; Digby, W.M.; Williams, C.W.; Andreaco, M. [CTI, Inc., Knoxville, TN (United States)

    1992-11-01

    We present initial performance results for a new multi-layer PET detector module consisting of an array of 3 mm square by 30 mm deep BGO crystals coupled on one end to a single photomultiplier tube and on the opposite end to an array of 3 mm square silicon photodiodes. The photomultiplier tube provides an accurate timing pulse and energy discrimination for the all the crystals in the module, while the silicon photodiodes identify the crystal of interaction. When a single BGO crystal at +25{degree}C is excited with 511 key photons, we measure a photodiode signal centered at 700 electrons (e{sup {minus}}) with noise of 375 e{sup {minus}} fwhm. When a four crystal / photodiode module is excited with a collimated line source of 511 key photons, the crystal of interaction is correctly identified 82% of the time. The misidentification rate can be greatly reduced and an 8{times}8 crystal / photodiode module constructed by using thicker depletion layer photodiodes or cooling to 0{degrees}C.

  14. Silicon avalanche photodiode linear-array detector with multichannel scaling system for pulsed synchrotron X-ray experiments

    NASA Astrophysics Data System (ADS)

    Kishimoto, S.; Mitsui, T.; Haruki, R.; Yoda, Y.; Taniguchi, T.; Shimazaki, S.; Ikeno, M.; Saito, M.; Tanaka, M.

    2015-05-01

    We developed an X-ray detector system using a 64-pixel silicon avalanche photodiode (Si-APD) linear array and fast pulse-counting electronics for multichannel scaling. The Si-APD linear array consists of 64 pixels each 100 200 ? m2 in size, with a pixel pitch of 150 ? m and depletion depth of 10 ? m. The fast electronics, consisting of an ultrafast application-specific integrated circuit and field-programmable gate arrays, can record both the position and timing of X-rays arriving at each pixel of the linear array with 1 ns pulse-pair resolution. The count distribution was measured using 14.4 keV synchrotron X-rays for nuclear resonant forward scattering experiments on 57Fe, and the spatial resolution was improved by inclining the detector. We also successfully measured amorphous alloy Fe78Si9B13 during heating.

  15. Simultaneous determination of catechins, caffeine and gallic acids in green, Oolong, black and pu-erh teas using HPLC with a photodiode array detector

    Microsoft Academic Search

    Yuegang Zuo; Hao Chen; Yiwei Deng

    2002-01-01

    A simple and fast HPLC method using a photodiode array detector was developed for simultaneous determination of four major catechins, gallic acid and caffeine. After multiple extractions with aqueous methanol and acidic methanol solutions, tea extract was separated within 20 min using a methanol朼cetate杦ater buffer gradient elution system on a C18 column. The sample extraction data demonstrated that the single

  16. Linear terrestrial laser scanning using array avalanche photodiodes as detectors for rapid three-dimensional imaging.

    PubMed

    Cai, Yinqiao; Tong, Xiaohua; Tong, Peng; Bu, Hongyi; Shu, Rong

    2010-12-01

    As an active remote sensor technology, the terrestrial laser scanner is widely used for direct generation of a three-dimensional (3D) image of an object in the fields of geodesy, surveying, and photogrammetry. In this article, a new laser scanner using array avalanche photodiodes, as designed by the Shanghai Institute of Technical Physics of the Chinese Academy of Sciences, is introduced for rapid collection of 3D data. The system structure of the new laser scanner is first presented, and a mathematical model is further derived to transform the original data to the 3D coordinates of the object in a user-defined coordinate system. The performance of the new laser scanner is tested through a comprehensive experiment. The result shows that the new laser scanner can scan a scene with a field view of 30 30 in 0.2 s and that, with respect to the point clouds obtained on the wall and ground floor surfaces, the root mean square errors for fitting the two planes are 0.21 and 0.01 cm, respectively. The primary advantages of the developed laser scanner include: (i) with a line scanning mode, the new scanner achieves simultaneously the 3D coordinates of 24 points per single laser pulse, which enables it to scan faster than traditional scanners with a point scanning mode and (ii) the new scanner makes use of two galvanometric mirrors to deflect the laser beam in both the horizontal and the vertical directions. This capability makes the instrument smaller and lighter, which is more acceptable for users. PMID:21124523

  17. Avalanche Photodiode Arrays for Optical Communications Receivers

    NASA Technical Reports Server (NTRS)

    Srinivasan, M.; Vilnrotter, V.

    2001-01-01

    An avalanche photodiode (APD) array for ground-based optical communications receivers is investigated for the reception of optical signals through the turbulent atmosphere. Kolmogorov phase screen simulations are used to generate realistic spatial distributions of the received optical field. It is shown that use of an APD array for pulse-position modulation detection can improve performance by up to 4 dB over single APD detection in the presence of turbulence, but that photon-counting detector arrays yield even greater gains.

  18. Chromatographic fingerprinting analysis of Zhizhu Wan preparation by high-performance liquid chromatography coupled with photodiode array detector

    PubMed Central

    Sun, Hui; Chen, Xi; Zhang, Aihua; Sakurai, Tetsuro; Jiang, Jinzhong; Wang, Xijun

    2014-01-01

    Background: Traditional Chinese medicine (TCM) formula has been used for over 1000 years and most of them contain complicate chemical constituents. Chromatographic fingerprinting has been widely accepted as a crucial method for qualitative and quantitative analyses for TCM. Zhi Zhu Wan (ZZW), a classical Chinese medical formula, has been commonly used for the treatment of gastrointestinal disease, which pose a serious challenge to its quality control. Materials and Methods: In this work, a sensitive and reliable method of high-performance liquid chromatography coupled with photodiode array detector (HPLC-PDA) was developed to control the quality of ZZW for chemical fingerprint analysis and quantitative analysis of four major bioactive constituents, including hesperidin, naringin, neohesperidin, and atractylenolide I. The chromatographic separation was performed on a Waters Symmetry C18 column (4.6 mm 250 mm, 5 ?m particle size), with an aqueous 0.095% phosphate acid and acetonitrile mobile phase gradient. Results: Optimization of other experimental conditions was validated with satisfactory accuracy, precision, repeatability, and recovery. In quantitative analysis, the four components showed good regression (R > 0.9994) within test ranges, and the recovery method ranged from 99.32% to 100.630%. HPLC fingerprints of the ZZW samples were compared by performing similarity analysis. Conclusion: The results indicated that the newly developed HPLC-PDA fingerprint method would be suitable for quality control of ZZW. PMID:25422548

  19. Instrumentation: Photodiode Array Detectors in UV-VIS Spectroscopy. Part II.

    ERIC Educational Resources Information Center

    Jones, Dianna G.

    1985-01-01

    A previous part (Analytical Chemistry; v57 n9 p1057A) discussed the theoretical aspects of diode ultraviolet-visual (UV-VIS) spectroscopy. This part describes the applications of diode arrays in analytical chemistry, also considering spectroelectrochemistry, high performance liquid chromatography (HPLC), HPLC data processing, stopped flow, and

  20. Large area avalanche photodiode detector array upgrade for a ruby-laser Thomson scattering system

    E-print Network

    Biewer, Theodore

    system have facilitated first-time measurements of the evolution of the electron temperature profile detectors. Over time, the system has evolved through minor and major technological upgrades, but the laser to pump the flashlamps and dissipate the excess heat. It can be operated in ``double pulse mode,'' however

  1. Nuclear resonant scattering measurements on 57Fe by multichannel scaling with a 64-pixel silicon avalanche photodiode linear-array detector

    NASA Astrophysics Data System (ADS)

    Kishimoto, S.; Mitsui, T.; Haruki, R.; Yoda, Y.; Taniguchi, T.; Shimazaki, S.; Ikeno, M.; Saito, M.; Tanaka, M.

    2014-11-01

    We developed a silicon avalanche photodiode (Si-APD) linear-array detector for use in nuclear resonant scattering experiments using synchrotron X-rays. The Si-APD linear array consists of 64 pixels (pixel size: 100 200 ?m2) with a pixel pitch of 150 ?m and depletion depth of 10 ?m. An ultrafast frontend circuit allows the X-ray detector to obtain a high output rate of >107 cps per pixel. High-performance integrated circuits achieve multichannel scaling over 1024 continuous time bins with a 1 ns resolution for each pixel without dead time. The multichannel scaling method enabled us to record a time spectrum of the 14.4 keV nuclear radiation at each pixel with a time resolution of 1.4 ns (FWHM). This method was successfully applied to nuclear forward scattering and nuclear small-angle scattering on 57Fe.

  2. Nuclear resonant scattering measurements on (57)Fe by multichannel scaling with a 64-pixel silicon avalanche photodiode linear-array detector.

    PubMed

    Kishimoto, S; Mitsui, T; Haruki, R; Yoda, Y; Taniguchi, T; Shimazaki, S; Ikeno, M; Saito, M; Tanaka, M

    2014-11-01

    We developed a silicon avalanche photodiode (Si-APD) linear-array detector for use in nuclear resonant scattering experiments using synchrotron X-rays. The Si-APD linear array consists of 64 pixels (pixel size: 100 200 ?m(2)) with a pixel pitch of 150 ?m and depletion depth of 10 ?m. An ultrafast frontend circuit allows the X-ray detector to obtain a high output rate of >10(7) cps per pixel. High-performance integrated circuits achieve multichannel scaling over 1024 continuous time bins with a 1 ns resolution for each pixel without dead time. The multichannel scaling method enabled us to record a time spectrum of the 14.4 keV nuclear radiation at each pixel with a time resolution of 1.4 ns (FWHM). This method was successfully applied to nuclear forward scattering and nuclear small-angle scattering on (57)Fe. PMID:25430093

  3. Design and evaluation of a 2D array PIN photodiode bump bonded to readout IC for the low energy x-ray detector.

    PubMed

    Yuk, Sunwoo; Park, Shin-Woong; Yi, Yun

    2006-01-01

    A 2D array radiation sensor, consisting of an array of PIN photodiodes bump bonded to readout integrated circuit (IC), has been developed for operation with low energy X-rays. The PIN photodiode array and readout IC for this system have been fabricated. The main performance measurements are the following: a few pA-scale leakage current, 350 pF junction capacitance, 30 microm-depth depletion layer and a 250 microm intrinsic layer at zero bias. This PIN photodiode array and readout IC were fabricated using a PIN photodiode process and standard 0.35 microm CMOS technology, respectively. The readout circuit is operated from a 3.3 V single power supply. Finally, a 2D array radiation sensor has been developed using bump bonding between the PIN photodiode and the readout electronics. PMID:17946079

  4. Conversion of a sequential inductively coupled plasma emission spectrometer into a multichannel simultaneous system using a photodiode array detector

    PubMed Central

    Ara鷍o, M醨io C閟ar Ugulino; Neto, Ben韈io de Barros; Pasquini, C閘io

    1998-01-01

    A monochannel plasma emission spectrometer was converted to a multichannel instrument by the introduction of a detection system based on an array of 1024 photodiodes and a low-resolution dispersion device. The new, relatively inexpensive equipment, features both the high speed typical of simultaneous instruments and the versatility of scanning systems. This paper reports on an evaluation of the modified equipment for quantitative analysis with the simultaneous determination of Al, Mn, Mg, Ca, Fe and Cu in a natural water matrix. An average relative prediction error of 2.4% was found which is the same as the error obtained with the conventional analytical method. Data acquisition with the modified instrument is up to 40 times faster. PMID:18924819

  5. The Use of Self-scanned Silicon Photodiode Arrays for Astronomical Spectrophotometry

    NASA Technical Reports Server (NTRS)

    Cochran, A. L.

    1984-01-01

    The use of a Reticon self scanned silicon photodiode array for precision spectrophotometry is discussed. It is shown that internal errors are + or - 0.003 mag. Observations obtained with a photodiode array are compared with observations obtained with other types of detectors with agreement, from 3500 A to 10500 A, of 1%. The photometric properties of self scanned photodiode arrays are discussed. Potential pitfalls are given.

  6. Stability of semiconductor photodiodes as VUV detectors

    NASA Astrophysics Data System (ADS)

    Tegeler, E.; Krumrey, M.

    1989-10-01

    The stability of semiconductor photodiodes originally designed for the visible spectral range has been investigated in the VUV. For silicon photodiodes a strong radiation-induced decrease of the responsitivity was found. The spectral dependence of this effect has been studied in the vicinity of the Si L absorption edge. GaAsP and GaP Schottky diodes show remarkable stability and high quantum efficiency. These photodiodes seem to be suitable as transfer standard detectors in the VUV.

  7. Multichannel photodiode detector for ultrafast optical spectroscopy

    NASA Astrophysics Data System (ADS)

    Mertelj, T.; Vuji?i?, N.; Borzda, T.; Vaskivskyi, I.; Pogrebna, A.; Mihailovic, D.

    2014-12-01

    Construction and characterization of a multichannel photodiode detector based on commercially available components with high signal to noise of 106 and a rapid frame rate, suitable for time resolved femtosecond spectroscopy with high repetition femtosecond sources, is presented.

  8. Vertical CNT-Si photodiode array.

    PubMed

    Ahnood, Arman; Zhou, Hang; Dai, Qing; Vygranenko, Yuri; Suzuki, Yuji; Esmaeili-Rad, Mr; Amaratunga, Gehan; Nathan, Arokia

    2013-09-11

    A photodiode consisting of nanopillars of thin-film silicon p-i-n on an array of vertically aligned carbon nanotubes (CNTs) with a noncontinuous cathode electrode is demonstrated. The structure exploits the intrinsic enhancement of the CNTs' electric field, which leads to reduction in the photodiode's operating voltage and response time and enhancement of optical coupling due to better light trapping, as compared with the conventional planar photodiode. These improvements translate to higher resolution and higher frame rate flat-panel imaging systems for a broad range of applications, including computed tomography and particle detection. PMID:23923984

  9. High-power flip-chip mounted photodiode array.

    PubMed

    Cross, Allen S; Zhou, Qiugui; Beling, Andreas; Fu, Yang; Campbell, Joe C

    2013-04-22

    Four-element modified uni-traveling-carrier (MUTC) photodiode arrays (PDA) flip-chip bonded onto transmission lines on AlN substrates are demonstrated. High RF output powers of 26.2 dBm and 21.0 dBm are achieved at 35 GHz and 48 GHz, respectively, using a PDA with 28-?m diameter photodiodes. A systematic comparison between a PDA with four 20 ?m-diameter elements and a discrete detector with the same active area (40-?m diameter) is presented. The PDA achieved higher output power and thermal dissipation compared to its discrete counterpart. PMID:23609702

  10. LSO\\/photodiode and LSO avalanche photodiode detectors

    Microsoft Academic Search

    C. L. Melcher

    1992-01-01

    The performance of Lu2(1-x)Ce2x(SiO4 )O (LSO) detectors was assessed under laboratory conditions. The PMT (photomultiplier tube) and the APD (avalanche photodiode) gave the same energy resolution when used with LSO, although the APD displayed a thermal noise threshold of 30 keV compared to <5 keV for the PMT. The PD resulted in a power energy resolution of 14% and also

  11. Photodiode array to charged aerosol detector response ratio enables comprehensive quantitative monitoring of basic drugs in blood by ultra-high performance liquid chromatography.

    PubMed

    Viinam鋕i, Jenni; Ojanper, Ilkka

    2015-03-20

    Quantitative screening for a broad range of drugs in blood is regularly required to assess drug abuse and poisoning within analytical toxicology. Mass spectrometry-based procedures suffer from the large amount of work required to maintain quantitative calibration in extensive multi-compound methods. In this study, a quantitative drug screening method for blood samples was developed based on ultra-high performance liquid chromatography with two consecutive detectors: a photodiode array detector and a corona charged aerosol detector (UHPLC-DAD-CAD). The 2.1 mm 150 mm UHPLC column contained a high-strength silica C18 bonded phase material with a particle size of 1.8 ?m, and the mobile phase consisted of methanol/0.1% trifluoroacetic acid in gradient mode. Identification was based on retention time, UV spectrum and the response ratio from the two detectors. Using historic calibration over a one-month period, the median precision (RSD) of retention times was 0.04% and the median accuracy (bias) of quantification 6.75%. The median precision of the detector response ratio over two orders of magnitude was 12%. The applicable linear ranges were generally 0.05-5 mg L(-1). The method was validated for 161 compounds, including antipsychotics, antidepressants, antihistamines, opioid analgesics, and adrenergic beta blocking drugs, among others. The main novelty of the method was the proven utility of the response ratio of DAD to CAD, which provided the additional identification efficiency required. Unlike with mass spectrometry, the high stability of identification and quantification allowed the use of facile historic calibration. PMID:25732578

  12. Optical Demonstrations with a Scanning Photodiode Array.

    ERIC Educational Resources Information Center

    Turman, Bobby N.

    1980-01-01

    Describes the photodiode array and the electrical connections necessary for it. Also shows a few of the optical demonstration possibilities-shadowgraphs for measuring small objects, interference and diffraction effects, angular resolution of an optical system, and a simple spectrometer. (Author/DS)

  13. Infrared Detector Arrays for Astronomy

    NASA Astrophysics Data System (ADS)

    Rieke, G. H.

    2007-09-01

    Use of infrared detector arrays in astronomy began roughly 20 years ago, and our detection capabilities in parts of this spectral range have doubled about every seven months since then. A variety of approaches are now used for detector arrays operating from 1 ?m to 1 mm and beyond. They include direct hybrid arrays of InSb and HgCdTe photodiodes that operate from 0.6 ?m to 5 ?m, and of Si:As impurity band conduction detectors from 5 ?m to 28 ?m; a number of approaches to photoconductive detector arrays in the far-infrared; and bolometer arrays read out by transistors or superconducting devices in the far-infrared through millimeter-wave spectral range. The underlying principles behind these approaches are discussed. The application of these principles is illustrated through detailed discussion of a number of state-of-the-art detector arrays.

  14. Current isolating epitaxial buffer layers for high voltage photodiode array

    DOEpatents

    Morse, Jeffrey D. (Martinez, CA); Cooper, Gregory A. (Pleasant Hill, CA)

    2002-01-01

    An array of photodiodes in series on a common semi-insulating substrate has a non-conductive buffer layer between the photodiodes and the semi-insulating substrate. The buffer layer reduces current injection leakage between the photodiodes of the array and allows optical energy to be converted to high voltage electrical energy.

  15. A fast and validated method for the determination of malondialdehyde in fish liver using high-performance liquid chromatography with a photodiode array detector.

    PubMed

    Faizan, Mohammad; Esatbeyoglu, Tuba; Bayram, Banu; Rimbach, Gerald

    2014-04-01

    Malondialdehyde (MDA) is a biomarker of lipid peroxidation and is present in foods and biological samples such as plasma. A high-performance liquid chromatography (HPLC) method was applied to determine MDA in fish liver samples after derivatization with 2,4-dinitrophenylhydrazine (DNPH) using a ODS2 column (10 cm 4.6 mm, 3 ?m) and a photodiode array detector. The mobile phase consisted of 0.2% acetic acid (v/v) in distilled water and acetonitrile (42:58, v/v). The present method was validated in terms of linearity, lower limit of quantification, lower limit of detection, precision, accuracy, recovery, and stability of MDA according to U.S. Food and Drug Administration (FDA) guidelines. The limit of quantification of MDA was 0.39 ?mol/L, which is comparable to other methods. The recovery of the spiked MDA liver samples was in the range of 92.4% to 104.2%. This newly modified HPLC method is specific, sensitive, and accurate and allows the analysis of MDA within 4 min in fish liver but also in other tissues and plasma. PMID:24621264

  16. Fingerprint analysis of Hibiscus mutabilis L. leaves based on ultra performance liquid chromatography with photodiode array detector combined with similarity analysis and hierarchical clustering analysis methods

    PubMed Central

    Liang, Xianrui; Ma, Meiling; Su, Weike

    2013-01-01

    Background: A method for chemical fingerprint analysis of Hibiscus mutabilis L. leaves was developed based on ultra performance liquid chromatography with photodiode array detector (UPLC-PAD) combined with similarity analysis (SA) and hierarchical clustering analysis (HCA). Materials and Methods: 10 batches of Hibiscus mutabilis L. leaves samples were collected from different regions of China. UPLC-PAD was employed to collect chemical fingerprints of Hibiscus mutabilis L. leaves. Results: The relative standard deviations (RSDs) of the relative retention times (RRT) and relative peak areas (RPA) of 10 characteristic peaks (one of them was identified as rutin) in precision, repeatability and stability test were less than 3%, and the method of fingerprint analysis was validated to be suitable for the Hibiscus mutabilis L. leaves. Conclusions: The chromatographic fingerprints showed abundant diversity of chemical constituents qualitatively in the 10 batches of Hibiscus mutabilis L. leaves samples from different locations by similarity analysis on basis of calculating the correlation coefficients between each two fingerprints. Moreover, the HCA method clustered the samples into four classes, and the HCA dendrogram showed the close or distant relations among the 10 samples, which was consistent to the SA result to some extent. PMID:23930008

  17. Identification and chemical profiling of monacolins in red yeast rice using high-performance liquid chromatography with photodiode array detector and mass spectrometry.

    PubMed

    Li, Yong-Guo; Zhang, Fang; Wang, Zheng-Tao; Hu, Zhi-Bi

    2004-09-01

    Monascus purpureus-fermented rice (red yeast rice) was one of the food supplements that had the ability of lowering the blood-lipid levels, and monacolins have been proved to be main active constituents. In total 14 monacolin compounds such as monacolin K (mevinolin), J, L, M, X, and their hydroxy acid form, as well as dehydromonacolin K, dihydromonacolin L, compactin, 3alpha-hydroxy-3,5-dihydromonacolin L, etc. were identified in red yeast rice, using high-performance liquid chromatography with photodiode array detector and tandem mass spectrometry. A chemical fingerprint profiling method to display bioactive monacolins in red yeast rice was established and could be used for the quality control of the target material and its related products. Ten finish products labeled as red yeast rice from different manufacturers in marketing were traced using the chromatographic chemical profiling method, and the results show that only two of them were similar while the other eight were significantly different from the reference red yeast rice. All of these materials including raw material powder and finished products available were quantified and the contents of monacolins were calculated with reference of monacolin K (mevinolin) as the standard. PMID:15336357

  18. Determining the pharmacokinetics of psilocin in rat plasma using ultra-performance liquid chromatography coupled with a photodiode array detector after orally administering an extract of Gymnopilus spectabilis.

    PubMed

    Chen, Jianbo; Li, Meijia; Yan, Xitao; Wu, Enqi; Zhu, Hongmei; Lee, Kwan Jun; Chu, Van Men; Zhan, Lifeng; Lee, Wonjae; Kang, Jong Seong

    2011-09-01

    This study established ultra-performance liquid chromatography coupled with a photodiode array detector for determining psilocin and its pharmacokinetics in rat plasma after orally administering an extract of Gymnopilus spectabilis. The extract was separated on an ODS C18 column (2.3 ?m, 100 mm 2.1 mm I.D.) by gradient elution with (A) water containing 50mM AcONH(4) and (B) acetonitrile. The wavelength was set at 265 nm and the injection volume was 10 ?L. Under these conditions, the calibration curve was linear over the concentration range 0.2-20 ?g/mL with a correlation coefficient of r(2)=0.9992. The inter- and intraday precision levels were less than 7% and the accuracies (%) were within the range 92.0-102.5%. The method was sufficiently valid to be applied to a pharmacokinetics study of psilocin in rat plasma. The pharmacokinetic parameters of psilocin in rat plasma after the oral administration of a G. spectabilis extract were as follows: C(max), 0.43 0.12 ?g/mL; T(max), 90 2.1 min; AUC(0?t), 1238.3 96.4 (?g/mL) min; and T(1/2), 117.3 40.3 min. PMID:21820980

  19. Multichannel photodiode detector for ultrafast optical spectroscopy.

    PubMed

    Mertelj, T; Vuji?i?, N; Borzda, T; Vaskivskyi, I; Pogrebna, A; Mihailovic, D

    2014-12-01

    Construction and characterization of a multichannel photodiode detector based on commercially available components with high signal to noise of ?10(6) and a rapid frame rate, suitable for time resolved femtosecond spectroscopy with high repetition femtosecond sources, is presented. PMID:25554276

  20. A validated stability-indicating HPLC with photodiode array detector (PDA) method for the stress tests of Monascus purpureus-fermented rice, red yeast rice

    Microsoft Academic Search

    Yong-Guo Li; Hong Liu; Zheng-Tao Wang

    2005-01-01

    A stability-indicating reversed phase high-performance liquid chromatography (RP-HPLC) with photodiode array (PDA) detection method was developed and validated for the assay of monacolin series compounds including monacolin K, L, J and their hydroxyl acid forms as well as dehydroxymonacolin K simultaneously in Monascus purpureus-fermented rice, red yeast rice. Well-resolved peaks of seven main compounds of monacolin family were profiled on

  1. ASIC Readout Circuit Architecture for Large Geiger Photodiode Arrays

    NASA Technical Reports Server (NTRS)

    Vasile, Stefan; Lipson, Jerold

    2012-01-01

    The objective of this work was to develop a new class of readout integrated circuit (ROIC) arrays to be operated with Geiger avalanche photodiode (GPD) arrays, by integrating multiple functions at the pixel level (smart-pixel or active pixel technology) in 250-nm CMOS (complementary metal oxide semiconductor) processes. In order to pack a maximum of functions within a minimum pixel size, the ROIC array is a full, custom application-specific integrated circuit (ASIC) design using a mixed-signal CMOS process with compact primitive layout cells. The ROIC array was processed to allow assembly in bump-bonding technology with photon-counting infrared detector arrays into 3-D imaging cameras (LADAR). The ROIC architecture was designed to work with either common- anode Si GPD arrays or common-cathode InGaAs GPD arrays. The current ROIC pixel design is hardwired prior to processing one of the two GPD array configurations, and it has the provision to allow soft reconfiguration to either array (to be implemented into the next ROIC array generation). The ROIC pixel architecture implements the Geiger avalanche quenching, bias, reset, and time to digital conversion (TDC) functions in full-digital design, and uses time domain over-sampling (vernier) to allow high temporal resolution at low clock rates, increased data yield, and improved utilization of the laser beam.

  2. A room temperature LSO\\/PIN photodiode PET detector module that measures depth of interaction

    Microsoft Academic Search

    W. W. Moses; S. E. Derenzo; C. L. Melcher; R. A. Manente

    1995-01-01

    We present measurements of a 4 element PET detector module that uses a 22 array of 3 mm square PIN photodiodes to both measure the depth of interaction (DOI) and identify the crystal of interaction. Each photodiode is coupled to one end of a 3󫢪5 mm LSO crystal, with the opposite ends of all 4 crystals attached to a single

  3. A polychromator-type near-infrared spectrometer with a high-sensitivity and high-resolution photodiode array detector for pharmaceutical process monitoring on the millisecond time scale

    NASA Astrophysics Data System (ADS)

    Murayama, Kodai; Genkawa, Takuma; Ishikawa, Daitaro; Komiyama, Makoto; Ozaki, Yukihiro

    2013-02-01

    In the fine chemicals industry, particularly in the pharmaceutical industry, advanced sensing technologies have recently begun being incorporated into the process line in order to improve safety and quality in accordance with process analytical technology. For estimating the quality of powders without preparation during drug formulation, near-infrared (NIR) spectroscopy has been considered the most promising sensing approach. In this study, we have developed a compact polychromator-type NIR spectrometer equipped with a photodiode (PD) array detector. This detector is consisting of 640 InGaAs-PD elements with 20-?m pitch. Some high-specification spectrometers, which use InGaAs-PD with 512 elements, have a wavelength resolution of about 1.56 nm when covering 900-1700 nm range. On the other hand, the newly developed detector, having the PD with one of the world's highest density, enables wavelength resolution of below 1.25 nm. Moreover, thanks to the combination with a highly integrated charge amplifier array circuit, measurement speed of the detector is higher by two orders than that of existing PD array detectors. The developed spectrometer is small (120 mm 220 mm 200 mm) and light (6 kg), and it contains various key devices including the high-density and high-sensitivity PD array detector, NIR technology, and spectroscopy technology for a spectroscopic analyzer that has the required detection mechanism and high sensitivity for powder measurement, as well as a high-speed measuring function for blenders. Moreover, we have evaluated the characteristics of the developed NIR spectrometer, and the measurement of powder samples confirmed that it has high functionality.

  4. A polychromator-type near-infrared spectrometer with a high-sensitivity and high-resolution photodiode array detector for pharmaceutical process monitoring on the millisecond time scale.

    PubMed

    Murayama, Kodai; Genkawa, Takuma; Ishikawa, Daitaro; Komiyama, Makoto; Ozaki, Yukihiro

    2013-02-01

    In the fine chemicals industry, particularly in the pharmaceutical industry, advanced sensing technologies have recently begun being incorporated into the process line in order to improve safety and quality in accordance with process analytical technology. For estimating the quality of powders without preparation during drug formulation, near-infrared (NIR) spectroscopy has been considered the most promising sensing approach. In this study, we have developed a compact polychromator-type NIR spectrometer equipped with a photodiode (PD) array detector. This detector is consisting of 640 InGaAs-PD elements with 20-?m pitch. Some high-specification spectrometers, which use InGaAs-PD with 512 elements, have a wavelength resolution of about 1.56 nm when covering 900-1700 nm range. On the other hand, the newly developed detector, having the PD with one of the world's highest density, enables wavelength resolution of below 1.25 nm. Moreover, thanks to the combination with a highly integrated charge amplifier array circuit, measurement speed of the detector is higher by two orders than that of existing PD array detectors. The developed spectrometer is small (120 mm 220 mm 200 mm) and light (6 kg), and it contains various key devices including the high-density and high-sensitivity PD array detector, NIR technology, and spectroscopy technology for a spectroscopic analyzer that has the required detection mechanism and high sensitivity for powder measurement, as well as a high-speed measuring function for blenders. Moreover, we have evaluated the characteristics of the developed NIR spectrometer, and the measurement of powder samples confirmed that it has high functionality. PMID:23464192

  5. Self-scanned photodiode array - High performance operation in high dispersion astronomical spectrophotometry

    NASA Technical Reports Server (NTRS)

    Vogt, S. S.; Tull, R. G.; Kelton, P.

    1978-01-01

    A multichannel spectrophotometric detector system has been developed using a 1024 element self-scanned silicon photodiode array, which is now in routine operation with the high-dispersion coude spectrograph of the University of Texas McDonald Observatory 2.7-m telescope. Operational considerations in the use of such arrays for high precision and low light level spectrophotometry are discussed. A detailed description of the system is presented. Performance of the detector as measured in the laboratory and on astronomical program objects is described, and it is shown that these arrays are highly effective detectors for high dispersion astronomical spectroscopy.

  6. High speed, high performance /Hg,Cd/Te photodiode detectors.

    NASA Technical Reports Server (NTRS)

    Soderman, D. A.; Pinkston, W. H.

    1972-01-01

    The current performance of high speed photodiode detectors for the 1 to 10 micron spectral region is discussed. The (Hg,Cd)Te photodiode configuration, detector properties, integration in laser receiver modules, and frequency response are considered for near infrared and far infrared wavelengths. The recent advances in (Hg,Cd)Te material and device development are indicated by the realization not only of exceptionally high speed detectors but of detectors that exhibit excellent detectivities. The performance improves substantially when the detector is cooled. This detector junction technology has been extended to other compositions of (Hg,Cd)Te for peak spectral responses at 5 and 10 micron.

  7. Silicon carbide photomultipliers and avalanche photodiode arrays for ultraviolet and solar-blind light detection

    Microsoft Academic Search

    Alexey Vert; Stanislav Soloviev; Alexander Bolotnikov; Peter Sandvik

    2009-01-01

    Silicon carbide is known for its large bandgap and suitability to make highly sensitive ultraviolet photo-detectors. These devices show appreciable quantum efficiencies in the 240 nm - 350 nm wavelength range in combination with low dark currents. We present recent results on 4H-SiC avalanche photodiode arrays and SiC-based solid-state photomultiplier arrays suitable for ultraviolet and solar-blind light detection. A novel

  8. Validated stability-indicating methods for the simultaneous determination of amiloride hydrochloride, atenolol, and chlorthalidone using HPTLC and HPLC with photodiode array detector.

    PubMed

    Youssef, Rasha M; Maher, Hadir M; El-Kimary, Eman I; Hassan, Ekram M; Barary, Magda H

    2013-01-01

    Two stability-indicating chromatographic methods are described for simultaneous determination of amiloride hydrochloride (AMI), atenolol (ATE), and chlorthalidone (CHL) in combined dosage forms. The first method was based on HPTLC separation of the three drugs followed by densitometric measurements of their bands at 274 nm. The separation was carried out on Merck HPTLC silica gel 60F254 aluminum sheets using chloroform-methanol-ammonia 27%, w/w (9 + 2 + 0.3, v/v/v) mobile phase. Analysis data was used for the linear regression graph in the range of 0.1-0.5, 0.8-5.0, and 0.3-1.5 microg/band for AMI, ATE, and CHL, respectively. The second method was based on an RP-HPLC separation of the cited drugs performed on an RP stainless steel C18 analytical column (250 x 4.6 mm id) with a gradient elution system of methanol and 0.05 M aqueous phosphate buffer adjusted to pH 4 as the mobile phase, at the flow rate of 1.0 mL/min. Quantitation was achieved with photodiode array detection at 275 nm for AMI and 225 nm for ATE and CHL. The calibration graphs for each drug were rectilinear in the range of 2-50, 25-150, and 2-100 microg/mL for AMI, ATE, and CHL, respectively. The proposed chromatographic methods were successfully applied for determination of the investigated drugs in pharmaceutical preparations. Both methods were validated in compliance with International Conference on Harmonization guidelines in terms of linearity, accuracy, precision, robustness, LOD, and LOQ. PMID:23767356

  9. A validated stability-indicating HPLC with photodiode array detector (PDA) method for the stress tests of Monascus purpureus-fermented rice, red yeast rice.

    PubMed

    Li, Yong-Guo; Liu, Hong; Wang, Zheng-Tao

    2005-09-01

    A stability-indicating reversed phase high-performance liquid chromatography (RP-HPLC) with photodiode array (PDA) detection method was developed and validated for the assay of monacolin series compounds including monacolin K, L, J and their hydroxyl acid forms as well as dehydroxymonacolin K simultaneously in Monascus purpureus-fermented rice, red yeast rice. Well-resolved peaks of seven main compounds of monacolin family were profiled on a C(18) reverse-phase column using a linear gradient of 0.1% trifluoroacetic acid and acetonitrile as the mobile phase, and the detection wavelength was set at 237nm. The method was validated with respect to specificity, chromatographic parameters, linearity, precision, accuracy, limits of detection and quantitation. The stability stress testing for fermented red yeast rice powder was carried out to show the effects of high temperature (80 degrees C), high humidity at room temperature (92.5% RH, 25 degrees C), high humidity at high temperature (75% RH, 60 degrees C) and light (sunlight) in solid state. The results exhibited that monacolins decreased significantly under the conditions of high humidity at high temperature (75% RH, 60 degrees C) and sunlight. Monacolin K and its hydroxyl acid form would be dehydrolyzed and turned to dehydromonacolin K at high temperature (80 degrees C) while the monacolin K, J and L would be transformed into their corresponding hydroxyl acid forms under the condition of high humidity (92.5% RH, 25 degrees C). The indication is that monacolins in red yeast rice powder are light-sensitive and thermal-sensitive. Therefore, it has been suggested that the preparations containing monacolins be stored in the place of cool and lightproof. The proposed degradation pathways were discussed as well. The multi-components assay for stability of botanical products could provide much more information than the normal marker-orientation method. PMID:15876509

  10. Photodiode

    NSDL National Science Digital Library

    Van Zeghbroeck, Bart Jozef

    This Quicktime presentation explains the basics of the photodiode. Some concepts that are explained include the photodiode package, photodiode illumination, internal connections, photodiode chip, photon absorption and electron-hole pair generation.

  11. Photodiode arrays having minimized cross-talk between diodes

    DOEpatents

    Guckel, Henry (Madison, WI); McNamara, Shamus P. (Madison, WI)

    2000-10-17

    Photodiode arrays are formed with close diode-to-diode spacing and minimized cross-talk between diodes in the array by isolating the diodes from one another with trenches that are formed between the photodiodes in the array. The photodiodes are formed of spaced regions in a base layer, each spaced region having an impurity type opposite to that of the base layer to define a p-n junction between the spaced regions and the base layer. The base layer meets a substrate at a boundary, with the substrate being much more heavily doped than the base layer with the same impurity type. The trenches extend through the base layer and preferably into the substrate. Minority carriers generated by absorption of light photons in the base layer can only migrate to an adjacent photodiode through the substrate. The lifetime and the corresponding diffusion length of the minority carriers in the substrate is very short so that all minority carriers recombine in the substrate before reaching an adjacent photodiode.

  12. Effect of a polywell leometry on a CMOS photodiode array

    Microsoft Academic Search

    Paul V. Jansz; Steven Hinckley; Graham Wild

    2010-01-01

    The effect of a polywell geometry hybridized with a stacked gradient poly-homojunction architecture, on the response of a CMOs compatible photodiode array was simulated. Crosstalk and sensitivity improved compared to the polywell geometry alone, for both back and front illumination.

  13. Effect of a Polywell geometry on a CMOS Photodiode Array

    Microsoft Academic Search

    Paul V Jansz; Steven Hinckley; Graham Wild

    2010-01-01

    The effect of a polywell geometry hybridized with a stacked gradient poly-homojunction architecture, on the response of a CMOs compatible photodiode array was simulated. Crosstalk and sensitivity improved compared to the polywell geometry alone, for both back and front illumination

  14. A Geiger-mode avalanche photodiode array for X-ray photon correlation spectroscopy.

    PubMed

    Johnson, I; Sadygov, Z; Bunk, O; Menzel, A; Pfeiffer, F; Renker, D

    2009-01-01

    X-ray photon correlation spectroscopy (XPCS) provides an opportunity to study the dynamics of systems by measuring the temporal fluctuations in a far-field diffraction pattern. A two-dimensional detector system has been developed to investigate fluctuations in the frequency range of several Hz to kHz. The X-ray detector system consists of a thin 100 microm scintillation crystal coupled to a Geiger-mode avalanche photodiode array. In this article the elements of the system are detailed and the detector for XPCS measurements is demonstrated. PMID:19096181

  15. Rapid characterisation and comparison of saponin profiles in the seeds of Korean Leguminous species using ultra performance liquid chromatography with photodiode array detector and electrospray ionisation/mass spectrometry (UPLC-PDA-ESI/MS) analysis.

    PubMed

    Ha, Tae Joung; Lee, Byong Won; Park, Ki Hun; Jeong, Seong Hun; Kim, Hyun-Tae; Ko, Jong-Min; Baek, In-Youl; Lee, Jin Hwan

    2014-03-01

    The present work was reported on investigation of saponin profiles in nine different legume seeds, including soybean, adzuki bean, cowpea, common bean, scarlet runner bean, lentil, chick pea, hyacinth bean, and broad bean using ultra performance liquid chromatography with photodiode array detector and electrospray ionisation/mass spectrometry (UPLC-PDA-ESI/MS) technique. A total of twenty saponins were characterised under rapid and simple conditions within 15min by the 80% methanol extracts of all species. Their chemical structures were elucidated as soyasaponin Ab (1), soyasaponin Ba (2), soyasaponin Bb (3), soyasaponin Bc (4), soyasaponin Bd (5), soyasaponin ?g (6), soyasaponin ?g (7), soyasaponin ?a (8), soyasaponin ?g (9), soyasaponin ?a (10), azukisaponin VI (11), azukisaponin IV (12), azukisaponin II (13), AzII (14), AzIV (15), lablaboside E (16), lablaboside F (17), lablaboside D (18), chikusetusaponin IVa (19), and lablab saponin I (20). The individual and total saponin compositions exhibited remarkable differences in all legume seeds. In particular, soyasaponin ?a (8) was detected the predominant composition in soybean, cowpea, and lentil with various concentrations. Interestingly, soybean, adzuki bean, common bean, and scarlet runner bean had high saponin contents, while chick pea and broad bean showed low contents. PMID:24176342

  16. Pyroelectric detector arrays

    NASA Technical Reports Server (NTRS)

    Fripp, A. L.; Robertson, J. B.; Breckenridge, R. (inventors)

    1982-01-01

    A pyroelectric detector array and the method for using it are described. A series of holes formed through a silicon dioxide layer on the surface of a silicon substrate forms the mounting fixture for the pyroelectric detector array. A series of nontouching strips of indium are formed around the holes to make contact with the backside electrodes and form the output terminals for individual detectors. A pyroelectric detector strip with front and back electrodes, respectively, is mounted over the strips. Biasing resistors are formed on the surface of the silicon dioxide layer and connected to the strips. A metallized pad formed on the surface of layer is connected to each of the biasing resistors and to the film to provide the ground for the pyroelectric detector array.

  17. Pyroelectric detector arrays

    NASA Technical Reports Server (NTRS)

    Fripp, A. L.; Robertson, J. B.; Breckenridge, R. A. (inventors)

    1982-01-01

    A pryoelectric detector array and the method for making it are described. A series of holes formed through a silicon dioxide layer on the surface of a silicon substrate forms the mounting fixture for the pyroelectric detector array. A series of nontouching strips of indium are formed around the holes to make contact with the backside electrodes and form the output terminals for individual detectors. A pyroelectric detector strip with front and back electrodes, respectively, is mounted over the strip. Biasing resistors are formed on the surface of the silicon dioxide layer and connected to the strips. A metallized pad formed on the surface of the layer is connected to each of the biasing resistors and to the film to provide the ground for the pyroelectric detector array.

  18. Large-Format AlGaN PIN Photodiode Arrays for UV Images

    NASA Technical Reports Server (NTRS)

    Aslam, Shahid; Franz, David

    2010-01-01

    A large-format hybridized AlGaN photodiode array with an adjustable bandwidth features stray-light control, ultralow dark-current noise to reduce cooling requirements, and much higher radiation tolerance than previous technologies. This technology reduces the size, mass, power, and cost of future ultraviolet (UV) detection instruments by using lightweight, low-voltage AlGaN detectors in a hybrid detector/multiplexer configuration. The solar-blind feature eliminates the need for additional visible light rejection and reduces the sensitivity of the system to stray light that can contaminate observations.

  19. Avalanche photodiode based detector for beam emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Dunai, D.; Zoletnik, S.; S醨k鰖i, J.; Field, A. R.

    2010-10-01

    An avalanche photodiode based (APD) detector for the visible wavelength range was developed for low light level, high frequency beam emission spectroscopy (BES) experiments in fusion plasmas. This solid state detector has higher quantum efficiency than photomultiplier tubes, and unlike normal photodiodes, it has internal gain. This paper describes the developed detector as well as the noise model of the electronic circuit. By understanding the noise sources and the amplification process, the optimal amplifier and APD reverse voltage setting can be determined, where the signal-to-noise ratio is the highest for a given photon flux. The calculations are compared to the absolute calibration results of the implemented circuit. It was found that for a certain photon flux range, relevant for BES measurements (?108-1010 photons/s), the new detector is superior to both photomultipliers and photodiodes, although it does not require cryogenic cooling of any component. The position of this photon flux window sensitively depends on the parameters of the actual experimental implementation (desired bandwidth, detector size, etc.) Several detector units based on these developments have been built and installed in various tokamaks. Some illustrative results are presented from the 8-channel trial BES system installed at Mega-Ampere Spherical Tokamak (MAST) and the 16-channel BES system installed at the Torus Experiment for Technology Oriented Research (TEXTOR).

  20. Avalanche photodiode based detector for beam emission spectroscopy

    SciTech Connect

    Dunai, D.; Zoletnik, S.; Sarkoezi, J. [KFKI Research Institute for Particle and Nuclear Physics, EURATOM Association, P.O. Box 49, H-1525 Budapest (Hungary); Field, A. R. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)

    2010-10-15

    An avalanche photodiode based (APD) detector for the visible wavelength range was developed for low light level, high frequency beam emission spectroscopy (BES) experiments in fusion plasmas. This solid state detector has higher quantum efficiency than photomultiplier tubes, and unlike normal photodiodes, it has internal gain. This paper describes the developed detector as well as the noise model of the electronic circuit. By understanding the noise sources and the amplification process, the optimal amplifier and APD reverse voltage setting can be determined, where the signal-to-noise ratio is the highest for a given photon flux. The calculations are compared to the absolute calibration results of the implemented circuit. It was found that for a certain photon flux range, relevant for BES measurements ({approx_equal}10{sup 8}-10{sup 10} photons/s), the new detector is superior to both photomultipliers and photodiodes, although it does not require cryogenic cooling of any component. The position of this photon flux window sensitively depends on the parameters of the actual experimental implementation (desired bandwidth, detector size, etc.) Several detector units based on these developments have been built and installed in various tokamaks. Some illustrative results are presented from the 8-channel trial BES system installed at Mega-Ampere Spherical Tokamak (MAST) and the 16-channel BES system installed at the Torus Experiment for Technology Oriented Research (TEXTOR).

  1. Avalanche photodiode based detector for beam emission spectroscopy.

    PubMed

    Dunai, D; Zoletnik, S; S醨k鰖i, J; Field, A R

    2010-10-01

    An avalanche photodiode based (APD) detector for the visible wavelength range was developed for low light level, high frequency beam emission spectroscopy (BES) experiments in fusion plasmas. This solid state detector has higher quantum efficiency than photomultiplier tubes, and unlike normal photodiodes, it has internal gain. This paper describes the developed detector as well as the noise model of the electronic circuit. By understanding the noise sources and the amplification process, the optimal amplifier and APD reverse voltage setting can be determined, where the signal-to-noise ratio is the highest for a given photon flux. The calculations are compared to the absolute calibration results of the implemented circuit. It was found that for a certain photon flux range, relevant for BES measurements (?10(8)-10(10)?photons/s), the new detector is superior to both photomultipliers and photodiodes, although it does not require cryogenic cooling of any component. The position of this photon flux window sensitively depends on the parameters of the actual experimental implementation (desired bandwidth, detector size, etc.) Several detector units based on these developments have been built and installed in various tokamaks. Some illustrative results are presented from the 8-channel trial BES system installed at Mega-Ampere Spherical Tokamak (MAST) and the 16-channel BES system installed at the Torus Experiment for Technology Oriented Research (TEXTOR). PMID:21034087

  2. A room temperature LSO/PIN photodiode PET detector module that measures depth of interaction

    SciTech Connect

    Moses, W.W.; Derenzo, S.E. [Lawrence Berkeley Lab., CA (United States)] [Lawrence Berkeley Lab., CA (United States); Melcher, C.L.; Manente, R.A. [Schlumberger-Doll Research, Ridgefield, CT (United States)] [Schlumberger-Doll Research, Ridgefield, CT (United States)

    1995-08-01

    The authors present measurements of a 4 element PET detector module that uses a 2 x 2 array of 3 mm square PIN photodiodes to both measure the depth of interaction (DOI) and identify the crystal of interaction. Each photodiode is coupled to one end of a 3 x 3 x 25 mm LSO crystal, with the opposite ends of all 4 crystals attached to a single PMT that provides a timing signal and initial energy discrimination. Each LSO crystal is coated with a ``lossy`` reflector, so the ratio of light detected in the photodiode and PMT depends on the position of interaction in the crystal, and is used to determine this position on an event by event basis. This module is operated at +25 C with a photodiode amplifier peaking time of 2 {micro}s. When excited by a collimated beam of 511 keV photons at the photodiode end of the module (i.e. closest to the patient), the DOI resolution is 4 mm fwhm and the crystal of interaction is identified correctly 95% of the time. When excited at the opposite end of the module, the DOI resolution is 13 mm fwhm and the crystal of interaction is identified correctly 73% of the time. The channel to channel variations in performance are minimal.

  3. Large aspect ratio detector array for space applications

    NASA Astrophysics Data System (ADS)

    Ewin, A.; Fortin, M.; Shu, P.; Das, N. C.; Aslam, S.; Smith, W.; McAdoo, J.

    1998-01-01

    At the Goddard Space Flight Center (GSFC) Detector Development Laboratory (DDL), we have custom designed and fabricated a chip which consists of an interleaved linear array of 1512 pinned photo-diode (PD) sensing pixels, which have dimensions 200 ?m6 ?m, together with a parallel detector register and a serial readout register. The registers use a triple polysilicon CCD design. This paper presents some aspects of the design, processing and operating techniques used for optimizing the full well capacity of the odd shaped photo-diodes, efficiency of photo-diode to CCD transfer and the charge handling capability of the various CCD/output structures. By using a pinning implant in the PD area together with a larger transfer gate voltage the desired photo-diode signal level of 5 Me- was achieved.

  4. An Array of Photodiodes for Monitoring Hydrocarbons Combustions Burners

    NASA Astrophysics Data System (ADS)

    Arias, P. Luis; Torres, I. Sergio; Sb醨baro, H. Daniel; Far韆s, F. Oscar

    2008-04-01

    A non-intrusive method for monitoring hydrocarbons, gas and oil flames, is introduced in this paper. The method is based in a radiometry measurement of the flame, which is implemented by using an array of silicon photodiodes with interference optical filters. The array is designed to cover wavelengths for evaluating the formation and behaviour of excited CH* and C2* radicals. These radicals CH* and C2* can be detected at centre wavelengths of 432 nm and 516 nm respectively. The radiometry analysis for monitoring non-confined oil flames was checked by a radiometer, using crosscorrelation data. These radicals are also measured for gas flames in the reaction region for a confined flame. Simple and low cost electronic was designed to drive the array of silicon photodiodes and they were set in an optical system and in a data acquisition system. The tests reported demonstrate that the flame condition can be adequately monitored for different air excess, different axial position as well as for different firing rate. Indeed, experimental test were taken for two power level: low and high firing rate. The fast response, the non-intrusive character and the instantaneous measurement of information make the proposed optical sensor a key to develop advances control strategies, which can be used successfully in combustion processes.

  5. Compact multispectral photodiode arrays using micropatterned dichroic filters

    NASA Astrophysics Data System (ADS)

    Chandler, Eric V.; Fish, David E.

    2014-05-01

    The next generation of multispectral instruments requires significant improvements in both spectral band customization and portability to support the widespread deployment of application-specific optical sensors. The benefits of spectroscopy are well established for numerous applications including biomedical instrumentation, industrial sorting and sensing, chemical detection, and environmental monitoring. In this paper, spectroscopic (and by extension hyperspectral) and multispectral measurements are considered. The technology, tradeoffs, and application fits of each are evaluated. In the majority of applications, monitoring 4-8 targeted spectral bands of optimized wavelength and bandwidth provides the necessary spectral contrast and correlation. An innovative approach integrates precision spectral filters at the photodetector level to enable smaller sensors, simplify optical designs, and reduce device integration costs. This method supports user-defined spectral bands to create application-specific sensors in a small footprint with scalable cost efficiencies. A range of design configurations, filter options and combinations are presented together with typical applications ranging from basic multi-band detection to stringent multi-channel fluorescence measurement. An example implementation packages 8 narrowband silicon photodiodes into a 9x9mm ceramic LCC (leadless chip carrier) footprint. This package is designed for multispectral applications ranging from portable color monitors to purpose- built OEM industrial and scientific instruments. Use of an eight-channel multispectral photodiode array typically eliminates 10-20 components from a device bill-of-materials (BOM), streamlining the optical path and shrinking the footprint by 50% or more. A stepwise design approach for multispectral sensors is discussed - including spectral band definition, optical design tradeoffs and constraints, and device integration from prototype through scalable volume production. Additional customization options are explored for application-specific OEM sensors integrated into portable devices using multispectral photodiode arrays.

  6. Pyroelectric Detector Arrays

    NASA Astrophysics Data System (ADS)

    Porter, S. G.

    1988-10-01

    Linear pyroelectric arrays of up to 64 elements have been available for some time. Individual array elements are defined by photolithographic electrode patterning on the pyroelectric ceramic, and absorption of radiation is maximised across the wavelength range of interest by electrodeposition of 'platinum black on to the active element electrodes. Direct thermal conduction paths between adjacent elements in a monolithic array produce significant amounts of thermal crosstalk, decreasing the image resolution. Reticulation techniques have therefore been developed to isolate the elements thermally and hence decrease the crosstalk. Detector elements are individually compensated by large non-blacked areas connected in series opposition with the active element. This provides cancellation of common mode signals such as those produced by temperature drift and vibration. Discrete JFET chips have traditionally been used as buffer amplifiers, but MOSFET arrays have now been developed, giving a significant simplification in assembly. In its simplest form the MOSFET array consists of 32 transistors integrated onto a single chip; two of these chips are used to provide the 64 source followers for a 64 element linear pyroelectric array. A major advantage of MOSFET arrays is the lower gate leakage current than that obtainable with JFETs. This results in a lower current noise, which is manifested as an improvement in D* at low frequencies. The advantage of the MOSFET buffers is even more marked at elevated temperatures, because the leakage current of a JFET is strongly temperature dependent. As the element count of linear arrays increases so do the problems of interfacing the array to the following electronics; packages with more than 68 leads are very bulky. One solution to this problem is to incorporate multiplexers into the package, thus reducing the number of connections needed. To this end, multiplexed MOSFET arrays have been developed. The disadvantage of multiplexing immediately after the source follower is that no noise bandwidth limiting can be incorporated before the multiplexer, and the high frequency noise is aliased into the base band. This leads to a deterioration in the achievable signal to noise ratio. In order to improve on this, an integrated circuit has been developed which consists of 16 rising gain amplifiers and band limiting filters followed by a 16 way multiplexer. Eight of these integrated circuits have been incorporated into a single hybrid with a 128 element pyroelectric array.

  7. Linear array of photodiodes to track a human speaker for video recording

    NASA Astrophysics Data System (ADS)

    DeTone, D.; Neal, H.; Lougheed, R.

    2012-12-01

    Communication and collaboration using stored digital media has garnered more interest by many areas of business, government and education in recent years. This is due primarily to improvements in the quality of cameras and speed of computers. An advantage of digital media is that it can serve as an effective alternative when physical interaction is not possible. Video recordings that allow for viewers to discern a presenter's facial features, lips and hand motions are more effective than videos that do not. To attain this, one must maintain a video capture in which the speaker occupies a significant portion of the captured pixels. However, camera operators are costly, and often do an imperfect job of tracking presenters in unrehearsed situations. This creates motivation for a robust, automated system that directs a video camera to follow a presenter as he or she walks anywhere in the front of a lecture hall or large conference room. Such a system is presented. The system consists of a commercial, off-the-shelf pan/tilt/zoom (PTZ) color video camera, a necklace of infrared LEDs and a linear photodiode array detector. Electronic output from the photodiode array is processed to generate the location of the LED necklace, which is worn by a human speaker. The computer controls the video camera movements to record video of the speaker. The speaker's vertical position and depth are assumed to remain relatively constant- the video camera is sent only panning (horizontal) movement commands. The LED necklace is flashed at 70Hz at a 50% duty cycle to provide noise-filtering capability. The benefit to using a photodiode array versus a standard video camera is its higher frame rate (4kHz vs. 60Hz). The higher frame rate allows for the filtering of infrared noise such as sunlight and indoor lighting-a capability absent from other tracking technologies. The system has been tested in a large lecture hall and is shown to be effective.

  8. High resolution, low energy avalanche photodiode X-ray detectors

    NASA Technical Reports Server (NTRS)

    Farrell, R.; Vanderpuye, K.; Entine, G.; Squillante, M. R.

    1991-01-01

    Silicon avalanche photodiodes have been fabricated, and their performance as X-ray detectors has been measured. Photon sensitivity and energy resolution were measured as a function of size and operating parameters. Noise thresholds as low as 212 eV were obtained at room temperature, and backscatter X-ray fluorescence data were obtained for aluminum and other light elements. It is concluded that the results with the X-ray detector are extremely encouraging, and the performance is challenging the best available proportional counters. While not at the performance level of either cryogenic silicon or HgI2, these device operate at room temperature and can be reproduced in large numbers and with much larger areas than typically achieved with HgI2. In addition, they are rugged and appear to be indefinitely stable.

  9. High resolution, low energy avalanche photodiode X-ray detectors

    NASA Astrophysics Data System (ADS)

    Farrell, R.; Vanderpuye, K.; Entine, G.; Squillante, M. R.

    1991-04-01

    Silicon avalanche photodiodes have been fabricated, and their performance as X-ray detectors has been measured. Photon sensitivity and energy resolution were measured as a function of size and operating parameters. Noise thresholds as low as 212 eV were obtained at room temperature, and backscatter X-ray fluorescence data were obtained for aluminum and other light elements. It is concluded that the results with the X-ray detector are extremely encouraging, and the performance is challenging the best available proportional counters. While not at the performance level of either cryogenic silicon or HgI2, these device operate at room temperature and can be reproduced in large numbers and with much larger areas than typically achieved with HgI2. In addition, they are rugged and appear to be indefinitely stable.

  10. Solid state neutron detector array

    DOEpatents

    Seidel, John G. (Pittsburgh, PA); Ruddy, Frank H. (Monroeville, PA); Brandt, Charles D. (Mount Lebanon, PA); Dulloo, Abdul R. (Pittsburgh, PA); Lott, Randy G. (Pittsburgh, PA); Sirianni, Ernest (Monroeville, PA); Wilson, Randall O. (Greensburg, PA)

    1999-01-01

    A neutron detector array is capable of measuring a wide range of neutron fluxes. The array includes multiple semiconductor neutron detectors. Each detector has a semiconductor active region that is resistant to radiation damage. In one embodiment, the array preferably has a relatively small size, making it possible to place the array in confined locations. The ability of the array to detect a wide range of neutron fluxes is highly advantageous for many applications such as detecting neutron flux during start up, ramp up and full power of nuclear reactors.

  11. Solid state neutron detector array

    DOEpatents

    Seidel, J.G.; Ruddy, F.H.; Brandt, C.D.; Dulloo, A.R.; Lott, R.G.; Sirianni, E.; Wilson, R.O.

    1999-08-17

    A neutron detector array is capable of measuring a wide range of neutron fluxes. The array includes multiple semiconductor neutron detectors. Each detector has a semiconductor active region that is resistant to radiation damage. In one embodiment, the array preferably has a relatively small size, making it possible to place the array in confined locations. The ability of the array to detect a wide range of neutron fluxes is highly advantageous for many applications such as detecting neutron flux during start up, ramp up and full power of nuclear reactors. 7 figs.

  12. SWIR to LWIR HDVIP HgCdTe detector array performance

    Microsoft Academic Search

    A. I. D'Souza; M. G. Stapelbroek; L. Dawson; P. Ely; C. Yoneyama; J. Reekstin; M. R. Skokan; M. A. Kinch; P. K. Liao; M. J. Ohlson; P. J. Ronci; T. Teherani; H. D. Shih; J. Robinson

    2006-01-01

    DRS uses LPE-grown SWIR, MWIR and LWIR HgCdTe material to fabricate High-Density Vertically Integrated Photodiode (HDVIP) architecture detectors. 2.5 mum, 5.3 mum and 10.5 mum cutoff detectors have been fabricated into linear arrays as technology demonstrations targeting remote sensing programs. This paper presents 320 x 6 array configuration technology demonstrations' performance of HDVIP HgCdTe detectors and single detector noise data.

  13. Application of a photodiode-array optical turbulence sensor to wind studies in complex terrain

    SciTech Connect

    Porch, W.M.; Green, T.J.

    1980-04-01

    A digital photodiode-array optical turbulence sensor was used to gather data simultaneously with analog optical anemometer measurements during the July 1979 ASCOT experiment. This system provided useful information regarding the uniformity of optical turbulence used by the optical anemometer to derive cross-path wind speeds. Wind speeds derived from digital analysis of the photodiode-array intensities also provided an independent measure of the cross-path wind speed. Close agreement was found between these two measures of the wind.

  14. Photoelectron counting with an image intensifier tube and a self-scanned photodiode array

    NASA Technical Reports Server (NTRS)

    Sandel, B. R.; Broadfoot, A. L.

    1976-01-01

    A self-scanned photodiode array was fiber-optically coupled to an ITT proximity-focused image intensifier tube. It was determined that a single photoelectron event produces 34,000 charge carriers in a photodiode. This charge is only a factor of 2.8 above the rms noise level of the preamplifier used in the tests, but standard charge-sensitive techniques are at least a factor of 12 better. The image tube and photodiode array combination can be packaged in a disk 5.1 cm in diameter and 2.6 cm thick.

  15. Electrical characteristic signatures for non-uniformity analysis in HgCdTe photodiode arrays

    NASA Astrophysics Data System (ADS)

    Saxena, Raghvendra Sahai; Nokhwal, Radheshyam; Bhan, R. K.; Sharma, R. K.

    2013-01-01

    In this paper we present a method of analyzing the performance non-uniformity of HgCdTe photodiode arrays for infrared imaging applications. For quantifying the characteristic behavior of various photodiodes, we have parametrized the dynamic resistance verses voltage signatures in such a way that the obtained signature parameters have some relevance with different physical parameters. We also estimated the sensitivity of the proposed signatures on physical parameters using statistical technique. These characteristics signatures may be used to quantify the non-uniformity of the HgCdTe photodiodes in IR imaging arrays and its analysis. The method presented here is based on theoretical calculation of MWIR HgCdTe photodiodes. However, the method is generic and may be implemented on any other type of diode arrays for theoretical or experimental analysis of their non-uniformity.

  16. Advanced UV Detectors and Detector Arrays

    NASA Technical Reports Server (NTRS)

    Pankove, Jacques I.; Torvik, John

    1998-01-01

    Gallium Nitride (GaN) with its wide energy bandgap of 3.4 eV holds excellent promise for solar blind UV detectors. We have successfully designed, fabricated and tested GaN p-i-n detectors and detector arrays. The detectors have a peak responsivity of 0.14A/W at 363 nm (3.42 eV) at room temperature. This corresponds to an internal quantum efficiency of 56%. The responsivity decreases by several orders of magnitude to 0.008 A/W at 400 nm (3.10 eV) giving the excellent visible rejection ratio needed for solar-blind applications.

  17. Ultra high performance liquid chromatography with photodiode array detector and quadrupole time-of-flight tandem mass spectrometry coupled with discriminant analysis to evaluate Angelicae pubescentis radix from different regions.

    PubMed

    Ge, Ai-Hua; Ma, Wen-Fang; Wang, Chun-Peng; Li, Jin; He, Jun; Liu, Er-Wei; Adelakum, Tiwalade Adegoke; Zhang, Bo-Li; Gao, Xiumei; Chang, Yan-Xu

    2014-09-01

    A rapid and effective method was developed for the qualitative and quantitative analysis of the major chemical constituents in Angelicae pubescentis radix by ultra high performance liquid chromatography with photodiode array detection and quadrupole time-of-flight tandem mass spectrometry. The chromatographic separation was achieved on an ACQUITY UHPLC BEH C18 column (2.1 100 mm, 1.7 ?m). Nine phenolic acids, 30 coumarins, bisabolangelone, and adenosine were identified by quadrupole time-of-flight tandem mass spectrometry. All calibration curves exhibited good linearity (r > 0.9996) within the linear ranges. The relative standard deviation calculated for intraday and interday precision, stability, and accuracy were <5%. The mean recovery ranged from 95.8 to 106%. The overall limits of detection and quantification were 0.025-0.160 and 0.100-0.560 ?g/mL, respectively. Discriminant analysis was investigated as a method for evaluating the quality of the samples with 100% correction in their classification. The results demonstrated that the developed method could successfully be used to differentiate samples from different regions and could be a helpful tool for detection and confirmation of the quality of traditional Chinese medicines. PMID:25044521

  18. Development of a large pixel, spectrally optimized, pinned photodiode/interline charge coupled device (CCD) detector for the Earth Observing System (EOS)/Moderate-Resolution Imaging Spectrometer-Tilt (MODIS-T) instrument

    NASA Technical Reports Server (NTRS)

    Ewin, Audrey J.; Jhabvala, Murzy; Shu, Peter K.

    1991-01-01

    A pinned photodiode/interline CCD Detector Array is under development for the EOS/MODIS-T project. Outstanding features of the device include large pixels, spectrally optimized fill factors, and blooming protection. The detector has 30 spatial rows and 32 spectral columns. The device layout is split into two halves; each half has its own detector area, storage area, and output structure.

  19. Infrared detector arrays: Electronic interface analysis, design, and modeling

    NASA Astrophysics Data System (ADS)

    Howard, Steven G.

    1998-11-01

    Advances in infrared (IR) detector technology coupled with advances in analog Si CMOS technology have resulted in on-focal-plane hybrid integration of high performance Si readout circuitry with high density IR detector arrays made from a variety of low bandgap semiconductor materials. This dissertation focuses on characterizations or several linear IR photodiode arrays employing on- focal-plane Si CMOS readout circuitry. Significant performance improvements are reported using buffered capacitive transimpedance amplifiers (CTIA) to interconnect with photodiode arrays instead of reverse- biased, self-integrating techniques. Near zero volt detector bias is maintained by buffered interfacing techniques which greatly reduce dark currents and improve linearity. Key performance issues are CMOS op amp input offset voltage and input voltage noise. Emphasis has been placed on noise analysis as improved modeling has revealed dominating noise sources to be preamp white noise and preamp 1/f noise. Preamp white noise dominates at shorter exposure times while preamp 1/f noise dominates at longer exposure times on InGaAs arrays evaluated. Under small detector bias conditions (<20 mV) applied by CMOS op amp input offset voltage, detector 1/f noise limits sensitivity of Ge arrays at longer exposure times. Analytical tools developed explain direct increases in noise equivalent input charge or noise equivalent electrons with exposure time. Detector thermal shot noise, with a square root dependence On exposure time never limits sensitivity of devices evaluated. Improved models for the critical interface between IR detector and readout circuitry will greatly assist evaluating recommended improvements in IR detector and CMOS op amp design.

  20. Massively parallel MRI detector arrays.

    PubMed

    Keil, Boris; Wald, Lawrence L

    2013-04-01

    Originally proposed as a method to increase sensitivity by extending the locally high-sensitivity of small surface coil elements to larger areas via reception, the term parallel imaging now includes the use of array coils to perform image encoding. This methodology has impacted clinical imaging to the point where many examinations are performed with an array comprising multiple smaller surface coil elements as the detector of the MR signal. This article reviews the theoretical and experimental basis for the trend towards higher channel counts relying on insights gained from modeling and experimental studies as well as the theoretical analysis of the so-called "ultimate" SNR and g-factor. We also review the methods for optimally combining array data and changes in RF methodology needed to construct massively parallel MRI detector arrays and show some examples of state-of-the-art for highly accelerated imaging with the resulting highly parallel arrays. PMID:23453758

  1. Bright Spots: UV Measurements Using a Vacuum Photodiode Array

    NASA Astrophysics Data System (ADS)

    Perkins, Rory; Bellan, Paul

    2010-11-01

    Solar coronal loops typically erupt abruptly after long quiescent periods. Such eruptions might be initiated by interactions between adjacent loops; this possibility was explored in a laboratory experiment where two plasma-filled flux tubes merge in either a co-or counter-helicity arrangement (J.F. Hansen, S.K.P. Tripathi, and P.M. Bellan, Phys. Plasma 2, 3177(2004)). The latter arrangement produces a bright region with enhanced soft x-ray emission. We investigate such mergings with a new array of EUV photo-detectors (based on S.J. Zweben, R.J. Taylor, Plasma Physics, Vol. 23, No. 4(1981)) that provides spatially and temporally resolved measurements of radiation between 10 and 120 nm. The detector boasts a sub-microsecond rise-time and provides a large signal without amplification. The detector is shielded from the charged particle background by permanent magnets. A novel two-step scheme diverts RF ground loop currents and greatly improves the signal-to-noise ratio.

  2. Characterization of avalanche photodiodes for lidar atmospheric return signal detectors

    NASA Technical Reports Server (NTRS)

    Antill, C. W., Jr.; Holloway, R. M.

    1988-01-01

    Results are presented from tests to characterize noise, dark current, overload, and gain versus bias, relationships of ten avalanche photodiodes. The advantages of avalanche photodiodes over photomultiplier tubes for given laser wavelengths and return signal amplitudes are outlined. The relationship between responsivity and temperature and dark current and temperature are examined. Also, measurements of the noise equivalent power, the excess noise factor, and linearity are given. The advantages of using avalanche photodiodes in the Lidar Atmospheric Sensing Experiment and the Lidar In-Space Technology Experiment are discussed.

  3. Using Photodiodes in the Laboratory.

    ERIC Educational Resources Information Center

    Jenkins, T. E.

    1995-01-01

    Describes the most popular optical detector in the design of photodiode detector circuits. Discusses how a photodiode works, points to consider in the design of a photodiode, and photodiode hybrids. (AIM)

  4. Development of Low Noise, BackSide Illuminated Silicon Photodiode Arrays 1

    E-print Network

    for the technology development is a phosphorus璬oped, polycrystalline璼ilicon gettering technique originally usedDevelopment of Low Noise, Back璖ide Illuminated Silicon Photodiode Arrays 1 S.E. Holland Member, the energy resolution is 12% fwhm. I. INTRODUCTION The motivation for this work is to develop silicon

  5. Development of high transmittance, back-illuminated, silicon-on-sapphire substrates for high quantum efficiency and high resolution avalanche photodiode imaging arrays

    Microsoft Academic Search

    Alvin G. Stern

    2011-01-01

    There is a growing need in medical, scientific and industrial applications for dual-mode, passive and active 2D and 3D LADAR imaging methods. To fill this need, solid state, single-photon sensitive silicon avalanche photodiode (APD) detector arrays offer high sensitivity and the possibility to operate with wide dynamic range in dual linear and Geiger-mode for passive and active imaging. Although silicon

  6. Two-dimensional gate-controlled photodiode array for optical computing

    SciTech Connect

    Sun, C.C. (Univ., of Toronto, Dept. of Electrical Engineering, Toronto (CA))

    1989-08-01

    A new semiconductor device, the gate-controlled photodiode (GCPD), has been experimentally demonstrated. A two-dimensional (2-D) GCPD array may fulfill the combined function of a 2-D spatial light modulator (SLM) and a photodetector array in some applications. Its high parallelism, simplicity, and compatibility are attractive for optical signal processing and computing, optical interconnection for VLSI circuits, and artificial neural networks. Some typical applications for optical computing are discussed.

  7. A new photodiode readout scheme for high resolution scintillation crystal arrays

    SciTech Connect

    Levin, C.S.; Hoffman, E.J. [UCLA School of Medicine, Los Angeles, CA (United States)

    1996-12-31

    We are exploring the possibility of using PIN photodiodes to readout the scintillation crystals used in Positron Emission Tomography (PET) detector designs. Solid state photodetectors typically have a lower signal to noise ratio than photomultiplier tubes (PMTs). However, they have the advantage of compactness, and, thus, scintillation crystal readout schemes not available to PMTs because of their size and geometry limitations, are readily available to photodiodes. With current PET detector designs, only a small fraction of the available scintillation light created from 511 keV gamma ray collection studies were performed for several crystal geometries and surface treatments using both simulations and measurements. In this report, we present a feasible photodiode readout scheme that allows greater than 90% of the available scintillation light created in either BGO or LSO scintillation crystals to be collected by the photodiode readout somewhat compensates for its lower inherent signal to noise ratios and makes it feasible for use in PET. In addition, a coincident timing spectrum resolution of 3.5 ns FWHM was measured using small crystals of LSO, one coupled to a photodiode, the other to a PMT.

  8. A prototype high-resolution animal positron tomograph with avalanche photodiode arrays and LSO crystals

    Microsoft Academic Search

    Sibylle I. Ziegler; Bernd J. Pichler; Guido Boening; Magdalena Rafecas; Wendelin Pimpl; Eckart Lorenz; Norbert Schmitz; Markus Schwaiger

    2001-01-01

    To fully utilize positron emission tomography (PET) as a non-invasive tool for tissue characterization, dedicated instrumentation is being developed which is specially suited for imaging mice and rats. Semiconductor detectors, such as avalanche photodiodes (APDs), may offer an alternative to photomultiplier tubes for the readout of scintillation crystals. Since the scintillation characteristics of lutetium oxyorthosilicate (LSO) are well matched to

  9. Grating spectrograph integrated with photodiode array in InGaAsP\\/InGaAs\\/InP

    Microsoft Academic Search

    C. Cremer; N. Emeis; M. Schier; G. Heise; G. Ebbinghaus; L. Stoll

    1992-01-01

    A grating spectrograph integrated monolithically for the first time in the InGaAsP system with a photodiode array for a dense WDM application is presented for the 1.5 ?m wavelength region. The chip provides 42 wavelength channels with a spacing of 4 mm, a channel crosstalk of approximately -15 dB, an internal photodiode efficiency of 90%, and a photodiode capacitance of

  10. Infrared detectors, sensors, and focal plane arrays; Proceedings of the Meeting, San Diego, CA, Aug. 21, 22, 1986

    SciTech Connect

    Nakamura, H.

    1986-01-01

    Recent advances in IR detectors and their applications are discussed in reviews and reports. Topics addressed include the low-temperature characteristics of InSb photodiodes, B implantation through photochemically deposited SiO/sub 2/ films on Hg(1-x)Cd(x)Te, InAs photovoltaic detectors, detector arrays for low-background space IR astronomy, and buttable arrays of 300 multiplexed InGaAs photodiodes for SWIR imaging. Consideration is given to image-intensification techniques, narrow-band imaging at 8-14 microns, comparison measurements of low-level IR radiometers, and a cryogenic Michelson interferometer spectrometer for Space Shuttle application.

  11. Simultaneous determination of five aluminum lake dyes in chewing gum by HPLC with photodiode array detection.

    PubMed

    Yang, Yi; Yin, Jie; Shao, Bing

    2011-09-01

    A simple and rapid method has been developed and validated for the determination of five food aluminum lake dyes (Tartrazine Al lake, Sunset Yellow Al lake, Ponceau 4R Al lake, Allura Red Al lake and Brilliant Blue Al lake) in chewing gum. The dye portions of the target aluminum lakes were simultaneous extracted with 0.25 M NaOH and cleaned up by liquid-liquid extraction with dichloromethane, followed by further purification using Oasis WAX solid-phase extraction (SPE) cartridges. Analytes were separated by HPLC using an Inertsil ODS-3 column coupled to a photodiode array detector. The amounts of the aluminum lake dyes were finally quantified and indicated as their dye portions using corresponding calibration curves over ranges of 0.5 to 50 礸 ml(-1), with correlation coefficients >0.9999. Recoveries of the dye parts in aluminum lake dyes (spiked at levels of 1, 5, 25 礸 g(-1)) ranged from 72.5 to 116.4%, with relative standard deviations between 0.9 and 6.5%. Limits of detection and limits of quantification for all analytes were 0.15 and 0.50 礸 g(-1), respectively. This method was successfully applied in real samples of chewing gum. PMID:21707267

  12. Design and Initial Results of New AXUV Photodiode Arrays for Bolometric Measurements in Compact Helical System

    NASA Astrophysics Data System (ADS)

    Suzuki, Chihiro; Toi, Kazuo; Okamura, Shoichi; Ida, Katsumi; Takahashi, Chihiro; Peterson, Byron J.

    2002-11-01

    Absolute extreme ultraviolet photodiode (AXUVD) has recently been applied to bolometric measurements of the plasmas because of its nearly flat spectral response over wide photon energy range. In this study, we have applied two 20 channel AXUVD arrays for a new tomographic radiation measurement in Compact Helical System (CHS) heliotron/torsatron. The line of sights are arranged to cover all of the plasma volume from inward to outward shifted configurations. Photogenerated currents are transmitted to current-voltage converters with a factor of 10^5 V/A via a pair of parallel cables, then fed into VME-bus based analog-digital converters for data acquisition. A preliminary result of a single channel measurement exhibits sawtooth-like phenomena synchronized with burst modes of magnetic probes, which is hard to observe with standard bolometers, in low density plasmas sustained by co-injected NBI. Validity of AXUVD as a bolometric measurement in CHS is discussed based on comparison with a pyroelectric detector.

  13. Reliability of InGaAs detectors and arrays

    NASA Astrophysics Data System (ADS)

    Joshi, A. M.; Olsen, G. H.; Patil, S. R.

    1992-02-01

    The mean time to failure (MTTF) for InGaAs planar photodiodes was predicted to be 10 exp 14 hours at room temperature, based on life tests at temperatures of 200, 230, and 250 C (and -12 V reverse bias). This improved value is thought to be due to reductions in leakage current which lead to higher reliability. Significant reduction in background doping of the InGaAs absorption layer and mild doping (about 2 x 10 exp 16/cu cm) of the InP cap layer led to lower leakage currents. The typical room temperature leakage current of a 300 micron diameter photodiode is 300 pA at -5 V, and a 25 percent increase in this value constitutes a failure. For InGaAs photodiode arrays, an additional criterion of failure, 'popcorn noise' is introduced. Popcorn noise exhibits random charge (current) fluctuations in a p-n junction. The predicted MTTF for a 256-element In(0.53)Ga(0.47)As array is 100 hrs for one diode failure and 3 x 10 exp 9 hrs for five diode failures. Undegraded operation was observed with a group of In(0.8)Ga(0.2)As detectors (which absorb light out to 2.6 microns) after 8000 hrs at 125 C.

  14. Filtered and bare vacuum photodiode detectors for VUV monitoring of tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Zweben, S. J.; Taylor, R. J.

    1981-04-01

    The use of filtered and unfiltered vacuum photodiodes as broadband vacuum ultraviolet radiation detectors for tokamak plasmas is discussed. Bare vacuum photodiodes sensitive to wavelengths in the 50 to 1200 A range can be used as a monitor of discharge cleanliness by comparing the height of the hydrogen burnthrough peak to the height of the low-Z burnthrough peak. Vacuum photodiodes filtered with an aluminum silicon alloy foil having a transmission in the 150 to 700 A range are mainly sensitive to low-Z impurity radiation, and those filtered with polypropylene having a transmission in the 50 to 150 A range are sensitive to the hotter (electron temperature greater than or equal to 100 eV) part of the plasma. These detectors may be used on hotter tokamaks in the same way as conventional soft X-ray systems.

  15. Stressed detector arrays for airborne astronomy

    NASA Technical Reports Server (NTRS)

    Stacey, G. J.; Beeman, J. W.; Haller, E. E.; Geis, N.; Poglitsch, A.; Rumitz, M.

    1989-01-01

    The development of stressed Ge:Ga detector arrays for far-infrared astronomy from the Kuiper Airborne Observatory (KAO) is discussed. Researchers successfully constructed and used a three channel detector array on five flights from the KAO, and have conducted laboratory tests of a two-dimensional, 25 elements (5x5) detector array. Each element of the three element array performs as well as the researchers' best single channel detector, as do the tested elements of the 25 channel system. Some of the exciting new science possible with far-infrared detector arrays is also discussed.

  16. Application of a silicon photodiode array for solar edge tracking in the Halogen Occultation Experiment

    NASA Technical Reports Server (NTRS)

    Mauldin, L. E., III; Moore, A. S.; Stump, C. S.; Mayo, L. S.

    1985-01-01

    The optical and electronic design of the Halogen Occultation Experiment (HALOE) elevation sunsensor is described. This system uses a Galilean telescope to form a solar image on a linear silicon photodiode array. The array is a self-scanned, monolithic charge coupled device. The addresses of both solar edges imaged on the array are used by the control/pointing system to scan the HALOE science instantaneous-field-of-view (IFOV) across the vertical solar diameter during instrument calibration, and then maintain the science IFOV four arcmin below the top edge during the science data occultation event. Vertical resolution of 16 arcsec and a radiometric dynamic range of 100 are achieved at the 0.7 micrometer operating wavelength. The design provides for loss of individual photodiode elements without loss of angular tracking capability. The HALOE instrument is a gas correlation radiometer that is now being developed by NASA Langley Research Center for the Upper Atmospheric Research Satellite.

  17. Readout circuitry for continuous high-rate photon detection with arrays of InP Geiger-mode avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Frechette, Jonathan; Grossmann, Peter J.; Busacker, David E.; Jordy, George J.; Duerr, Erik K.; McIntosh, K. Alexander; Oakley, Douglas C.; Bailey, Robert J.; Ruff, Albert C.; Brattain, Michael A.; Funk, Joseph E.; MacDonald, Jason G.; Verghese, Simon

    2012-06-01

    An asynchronous readout integrated circuit (ROIC) has been developed for hybridization to a 32x32 array of single-photon sensitive avalanche photodiodes (APDs). The asynchronous ROIC is capable of simultaneous detection and readout of photon times of arrival, with no array blind time. Each pixel in the array is independently operated by a finite state machine that actively quenches an APD upon a photon detection event, and re-biases the device into Geiger mode after a programmable hold-off time. While an individual APD is in hold-off mode, other elements in the array are biased and available to detect photons. This approach enables high pixel refresh frequency (PRF), making the device suitable for applications including optical communications and frequency-agile ladar. A built-in electronic shutter that de-biases the whole array allows the detector to operate in a gated mode or allows for detection to be temporarily disabled. On-chip data reduction reduces the high bandwidth requirements of simultaneous detection and readout. Additional features include programmable single-pixel disable, region of interest processing, and programmable output data rates. State-based on-chip clock gating reduces overall power draw. ROIC operation has been demonstrated with hybridized InP APDs sensitive to 1.06-?m and 1.55-?m wavelength, and fully packaged focal plane arrays (FPAs) have been assembled and characterized.

  18. Effect of different drying methods on the quality of Angelicae Sinensis Radix evaluated through simultaneously determining four types of major bioactive components by high performance liquid chromatography photodiode array detector and ultra-high performance liquid chromatography quadrupole time-of-flight mass spectrometry.

    PubMed

    Bai, Ying-Jia; Kong, Ming; Xu, Jin-Di; Zhang, Xiao-Lin; Zhou, Shan-Shan; Wang, Xiao-Ning; Liu, Li-Fang; Li, Song-Lin

    2014-06-01

    In the present study, the effect of drying methods on the quality of Angelicae Sinensis Radix (DG), was evaluated by newly developed high performance liquid chromatography photodiode array detector (HPLC-DAD) and ultra-high performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS/MS). Ten major bioactive components including two phenolic acids, two hydroxyl phthalides, four alkyl phthalides and two phthalide dimers were selected as evaluation chemical markers and the newly-established method was qualitatively and quantitatively validated. DG slices and whole roots dried in shade, sun light, hot air, vacuum, microwave, far infrared ray and combination of microwave and far infrared ray as well as the fresh DG samples were determined by the established methods. DG slices dried in hot air kept the similar chemical composition to that of fresh DG, while DG whole roots dried in vacuum retained highest contents of the major components. Coniferyl ferulate and ligustilide degraded significantly in DG slices dried by microwave, far infrared ray and their combination. The influence of such chemical changes induced by different drying methods on the bioactivities of DG warrants further investigation, so that the optimal drying method can be obtained for the standardization of DG herb. PMID:24561333

  19. Filter-free integrated sensor array based on luminescence and absorbance measurements using ring-shaped organic photodiodes.

    PubMed

    Abel, Tobias; Sagmeister, Martin; Lamprecht, Bernhard; Kraker, Elke; K鰏tler, Stefan; Ungerb鯿k, Birgit; Mayr, Torsten

    2012-12-01

    An optical waveguiding sensor array featuring monolithically integrated organic photodiodes as integrated photo-detector, which simplifies the readout system by minimizing the required parts, is presented. The necessity of any optical filters becomes redundant due to the proposed platform geometry, which discriminates between excitation light and sensing signal. The sensor array is capable of measuring luminescence or absorption, and both sensing geometries are based on the identical substrate. It is demonstrated that background light is virtually non-existent. All sensing and waveguide layers, as well as in- and out-coupling elements are assembled by conventional screen-printing techniques. Organic photodiodes are integrated by layer-by-layer vacuum deposition onto glass or common polymer foils. The universal and simple applicability of this sensor chip is demonstrated by sensing schemes for four different analytes. Relative humidity, oxygen, and carbon dioxide are measured in gas phase using luminescence-based sensor schemes; the latter two analytes are also measured by absorbance-based sensor schemes. Furthermore, oxygen and pH in aqueous media were enabled. The consistency of calibration characteristics extending over different sensor chips is verified. PMID:22706404

  20. Integrating Pixel Array Detector Development

    NASA Astrophysics Data System (ADS)

    Gruner, Sol

    2009-03-01

    X-ray experiments are very frequently detector limited at storage ring synchrotron radiation sources, and will be even more so at future x-ray free electron laser and energy recovery linac sources. Limitations most frequently arise from the inability of detectors to efficiently collect and process data at the rates at which the data can be generated. Two bump-bonded silicon pixel array detectors (PADs) are being developed at Cornell University that will greatly enhance data collection capabilities. In these PADs x-rays are converted to electrical signals in a pixelated layer of high resistivity silicon, each pixel of which is connected by a metal solder ``bump'' to a corresponding pixel in a CMOS silicon integrated circuit. Each CMOS pixel contains its own data handling and processing electronics. Since all pixels operate in parallel, the PAD is capable of handling extremely high data throughput. The PAD pixels feature integrating analog front-end electronics which allow extremely high instantaneous count-rates, yet sufficiently high signal-to-noise to be able to detect single x-ray photons. The first PAD is designed for coherent x-ray imaging experiments at the Linac Coherent Light Source (LCLS) at SLAC. This detector frames continuously at the LCLS rate of 120 Hz, where the data for each frame can arrive in femtoseconds. The second detector, a result of a collaboration with the Area Detector Systems Corporation, is designed for high throughput protein crystallography experiments. Both detectors are described, and test data is provided. The capabilities of the detectors suggest a variety of new applications, some of which will be discussed.

  1. Performance comparison of barrier detectors and HgCdTe photodiodes

    NASA Astrophysics Data System (ADS)

    Martyniuk, Piotr; Rogalski, Antoni

    2014-10-01

    Barrier detectors are designed to reduce the dark current associated with Shockley-Read (SR) processes and to decrease the influence of surface leakage current without impeding photocurrent (signal). As a consequence, the absence of a depletion region in barrier detectors offers a way to overcome the disadvantage of the large depletion dark current. Therefore, they are typically implemented in materials with relatively poor SR lifetimes, such as all III-V compounds. It is shown here that despite numerous advantages of III-V barrier detectors over present-day detection technologies, including reduced tunneling and surface leakage currents, normal-incidence absorption, and suppressed Auger recombination, the promise of a superior performance with these detectors in comparison with HgCdTe photodiodes has not been realized yet. The dark current density is higher than that of bulk HgCdTe photodiodes, especially in the mid-wavelength infrared range.

  2. A design for a linear array PIN photodiode for use in a Computed mammo-Tomography (CmT) system

    NASA Astrophysics Data System (ADS)

    Park, Shin-Woong; Yuk, Sunwoo; Park, Jung-Byung; Yi, Yun

    2009-10-01

    A p-i-n (PIN) photodiode has been used in a solid-state detector for X-ray detection as a photosensor of visible light from the scintillator. The most sensitive material used as low-energy X-ray detector in the mammography system is a Gd 2O 2S (GOS). As the light from GOS having a short wavelength in the range of 450-700 nm (peak at 510 nm) is absorbed within a very shallow layer near the surface of photodiode before arriving at depletion region and does not contribute to the signal. For designing the PIN photodiode, it is important to make p-layer as shallow as possible. In order to achieve shallow junction, the optimum conditions of ion implantation such as thickness of SiO 2 oxide barrier, tilting angle of the wafer with respect to incident ion beam, and annealing conditions, have been determined using simulation results. The penetration depths are about 2 ?m for 510 nm, and 7 ?m for 700 nm. It is necessary for adequate depletion depth (about 10 ?m) to acquire the entire incident light. So far, wafers of ?1000 and ?150 ? cm resistivity were chosen, which offer about 15 and 6 ?m depletion depth, respectively. The pixel pitch of photodiode is 0.4 mm3.0 mm and one module has 64 channels in linear array. Depth of the active p-layer is under 0.3 ?m in zero bias. Measured leakage currents under 10 pA/mm 2 for both diodes and junction capacitances are 16 and 29 pF/mm 2 in zero bias for the diodes of ?150 and ?1000 ? cm resistivity, respectively. The breast phantom, which was scanned by the Computed mammo-Tomography (CmT) system with two different detector modules and the data acquisition system, was developed. Little differences for distinct light absorption were shown in the three-dimensional images acquired in this study.

  3. Fingerprint quality control of Tianjihuang by high-performance liquid chromatographyphotodiode array detection

    Microsoft Academic Search

    Li-wei Yang; Ding-hong Wu; Xi Tang; Wei Peng; Xiao-rui Wang; Yan Ma; Wei-wei Su

    2005-01-01

    A novel, simple and accurate fingerprint method was developed using high-performance liquid chromatographyphotodiode array detection (HPLC朌AD) for the quality control of Hypericum japonicum thunb (Tianjihuang), a Chinese herbal medicine used for the treatment of several bacterial diseases, infectious hepatitis, gastrointestinal disorder, internal hemorrhage and tumors. For the first time, the feasibility and advantages of employing chromatographic fingerprint were investigated and

  4. A two-dimensional intensified photodiode array for imaging spectroscopy

    NASA Technical Reports Server (NTRS)

    Tennyson, P. D.; Dymond, K.; Moos, H. W.; Feldman, P. D.; Mackey, E. F.

    1986-01-01

    The Johns Hopkins University is currently developing an instrument to fly aboard NASA's Space Shuttle as a Spartan payload in the late 1980s. This Spartan free flyer will obtain spatially resolved spectra of faint extended emission line objects in the wavelength range 750-1150 A at about 2-A resolution. The use of two-dimensional photon counting detectors will give simultaneous coverage of the 400 A spectral range and the 9 arc-minute spatial resolution along the spectrometer slit. The progress towards the flight detector is reported here with preliminary results from a laboratory breadboard detector, and a comparison with the one-dimensional detector developed for the Hopkins Ultraviolet Telescope. A hardware digital centroiding algorithm has been successfully implemented. The system is ultimately capable of 15-micron resolution in two dimensions at the image plane and can handle continuous counting rates of up to 8000 counts/s.

  5. Screening of seized emerging drugs by ultra-high performance liquid chromatography with photodiode array ultraviolet and mass spectrometric detection.

    PubMed

    Li, Li; Lurie, Ira S

    2014-04-01

    The use of psychoactive "designer drugs" has increased rapidly due to their varying and sometimes ambiguous legal status and their ready access via the Internet and at local "headshops." A quick screening method for samples containing these substances, using ultra-high performance liquid chromatography with photodiode array UV and mass spectrometric detection (UHPLC-PDA/UV-MS), is presented. The method enables the screening of a variety of samples containing emerging/reemerging drugs, including ?-keto phenethylamines (cathinone derivatives), synthetic cannabinoids/cannabimimetics, and phenethylamine derivatives. The use of dual detectors not only provides molecular weight information but also differentiates the drugs by their categories and in some cases even their sub-categories. Moreover, ring positional isomers of cathinone and phenethylamine derivatives can be easily differentiated by their retention times and UV spectra. PMID:24607709

  6. Localization of particle sources with detector arrays

    Microsoft Academic Search

    Arye Nehorai; Eytan Paldi

    1993-01-01

    Develops methods for localizing particle sources using detector arrays. Projection-based arrays are used and general convex, cubical, and spherical surfaces are investigated. Lower bounds are computed on the mean-square angular error (MSAE) for these arrays. The authors propose an algorithm for direction finding with the cubical array and analyze its MSAE. Potential applications of the proposed methods include finding radiation

  7. A prototype high-resolution animal positron tomograph with avalanche photodiode arrays and LSO crystals.

    PubMed

    Ziegler, S I; Pichler, B J; Boening, G; Rafecas, M; Pimpl, W; Lorenz, E; Schmitz, N; Schwaiger, M

    2001-02-01

    To fully utilize positron emission tomography (PET) as a non-invasive tool for tissue characterization, dedicated instrumentation is being developed which is specially suited for imaging mice and rats. Semiconductor detectors, such as avalanche photodiodes (APDs), may offer an alternative to photomultiplier tubes for the readout of scintillation crystals. Since the scintillation characteristics of lutetium oxyorthosilicate (LSO) are well matched to APDs, the combination of LSO and APDs seems favourable, and the goal of this study was to build a positron tomograph with LSO-APD modules to prove the feasibility of such an approach. A prototype PET scanner based on APD readout of small, individual LSO crystals was developed for tracer studies in mice and rats. The tomograph consists of two sectors (86 mm distance), each comprising three LSO-APD modules, which can be rotated for the acquisition of complete projections. In each module, small LSO crystals (3.7 x 3.7 x 12 mm3) are individually coupled to one channel within matrices containing 2x8 square APDs (2.6 x 2.6 mm2 sensitive area per channel). The list-mode data are reconstructed with a penalized weighted least squares algorithm which includes the spatially dependent line spread function of the tomograph. Basic performance parameters were measured with phantoms and first experiments with rats and mice were conducted to introduce this methodology for biomedical imaging. The reconstructed field of view covers 68 mm, which is 80% of the total detector diameter. Image resolution was shown to be 2.4 mm within the whole reconstructed field of view. Using a lower energy threshold of 450 keV, the system sensitivity was 350 Hz/MBq for a line source in air in the centre of the field of view. In a water-filled cylinder of 4.6 cm diameter, the scatter fraction at the centre of the field of view was 16% (450 keV threshold). The count rate was linear up to 700 coincidence counts per second. In vivo studies of anaesthetized rats and mice showed the feasibility of in vivo imaging using this PET scanner. The first LSO-APD prototype tomograph has been successfully introduced for in vivo animal imaging. APD arrays in combination with LSO crystals offer new design possibilities for positron tomographs with finely granulated detector channels. PMID:11303882

  8. Four-layer depth-of-interaction PET detector for high resolution PET using a multi-pixel S8550 avalanche photodiode

    NASA Astrophysics Data System (ADS)

    Nishikido, Fumihiko; Inadama, Naoko; Oda, Ichiro; Shibuya, Kengo; Yoshida, Eiji; Yamaya, Taiga; Kitamura, Keishi; Murayama, Hideo

    2010-09-01

    Avalanche photodiodes (APDs) are being used as photodetectors in positron emission tomography (PET) because they have many advantages over photomultipliers (PMTs) typically used in PET detectors. We have developed a PET detector that consists of a multi-pixel APD and a 6󬝰 array of 1.461.46 mm 24.5 m LYSO crystals for a small animal PET scanner. The detector can identify four-layer depth of interaction (DOI) with a position-sensitive APD coupled to the backside of a crystal array by just an optimized reflector arrangement. Since scintillation lights are shared among many pixels by the method, weaker signals in APD pixels far from the interacting crystals are affected by noise. To evaluate the performance of the four-layer DOI detector with the APD and the influence of electrical noise on our method, we constructed a prototype DOI detector and tested its performance. We found, except for crystal elements on the edge of the crystal array, all crystal elements could be identified from the 2D position histogram. An energy resolution of 16.9% was obtained for the whole crystal array of the APD detector. The results of noise dependence of detector performances indicated that the DOI detector using the APD could achieve sufficient performance even when using application-specific integrated circuits.

  9. Development of a flow-cell alpha detector utilizing microencapsulated CsI:Tl granules and silicon PIN-photodiodes

    Microsoft Academic Search

    Hui Tan; Timothy A. DeVol

    2002-01-01

    A flow-cell detector was developed utilizing microencapsulated granular CsI:Tl and silicon PIN-photodiodes for gross alpha radiation quantification. The CsI:Tl scintillator was crushed and sieved to 63-90 and 90-125 ?m particle size and encapsulated with 10% (ratio of coating layer mass to particle mass) of parylene C polymer. The radiation detector consisted of a CsI:Tl flow-cell and two silicon PIN-photodiodes (PDs).

  10. Development of a flow-cell alpha detector utilizing microencapsulated CsI:Tl granules and silicon PIN-photodiodes

    Microsoft Academic Search

    Hui Tan; Timothy A. DeVol

    2001-01-01

    A flow-cell detector was developed utilizing microencapsulated granular CsI:Tl and Si PIN-photodiode for gross alpha radiation quantification. The CsI:Tl scintillator was crushed and sieved to 63-90 and 90-125 ?m particle size and encapsulated with 10% (ratio of coating layer mass to particle mass) of Parylene C polymer. The radiation detector consisted of a CsI:Tl flow-cell and two silicon PIN-photodiodes (PDs).

  11. Performance comparison of barrier detectors and HgCdTe photodiodes

    NASA Astrophysics Data System (ADS)

    Martyniuk, P.; Rogalski, A.

    2014-06-01

    Recently, a new strategy used to achieve high operation temperature (HOT) infrared photodetectors including III-V compound materials (bulk materials and type-II superlattices) and cascade devices has been observed. Another method to reduce detector's dark current is reducing volume of detector material via a concept of photon trapping detector. The barrier detectors are designed to reduce dark current associated with Shockley-Read (SR) processes and to decrease influence of surface leakage current without impeding photocurrent (signal). In consequence, absence of a depletion region in barrier detectors offers a way to overcome the disadvantage of large depletion dark currents. So, they are typically implemented in materials with relatively poor SR lifetimes, such as all III-V compounds. From considerations presented in the paper results that despite numerous advantages of III-V barrier detectors over present-day detection technologies, including reduced tunneling and surface leakage currents, normal-incidence absorption, and suppressed Auger recombination, the promise of a superior performance of these detectors in comparison to HgCdTe photodiodes, has not been yet realized. The dark current density is higher than that of bulk HgCdTe photodiodes, especially in MWIR range. To attain their full potential, the following essential technological limitations such as short carrier lifetime, passivation, and heterostructure engineering, need to be overcome.

  12. Development of a testbed for flexible a-Si:H photodiode sensing arrays

    NASA Astrophysics Data System (ADS)

    Dominguez, Alfonso; Kunnen, George; Vetrano, Michael; Smith, Joseph; Marrs, Michael; Allee, David R.

    2013-05-01

    Large area, flexible sensing arrays for imaging, biochemical sensing and radiation detection are now possible with the development of flexible active matrix display technology. In particular, large-area flexible imaging arrays can provide considerable advancement in defense and security industries because of their inherent low manufacturing costs and physical plasticity that allows for increased adaptability to non-planar mounting surfaces. For example, a flexible array of photodetectors and lenslets formed into a cylinder could image simultaneously with a 360 degree view without the need for expensive bulky optics or a gimbaled mount. Here we report the design and development of a scalable 16x16 pixel testbed for flexible sensor arrays using commercial-off-the-shelf (COTS) parts and demonstrate the capture of a shadow image with an array of photodiodes and active pixel sensors on a plastic substrate. The image capture system makes use of an array of low-noise, InGaZnO active pixel amplifiers to detect changes in current in 2.4 ?m-thick reverse-biased a-Si:H PIN diodes. A thorough characterization of the responsivity, detectivity, and optical gain of an a- Si:H photodiode is also provided. At the back end, analog capture circuitry progressively scans the array and constructs an image based on the electrical activity in each pixel. The use of correlated-double-sampling to remove fixed pattern noise is shown to significantly improve spatial resolution due to process variations. The testbed can be readily adapted for the development of neutron, alpha-particle, or X-ray detection arrays given an appropriate conversion layer.

  13. A new silicon avalanche photodiode photon counting detector module for astronomy

    Microsoft Academic Search

    N. S. Nightingale; Cavendish Labomtov

    1990-01-01

    A new Silicon avalanche photodiode photon counting detector module with a peak detection efficiency of 45% and a maximum counting rate of more than 3,000,000cts\\/sec is described and its performance assessed over a range of operating conditions. The module should prove ideal for a wide variety of astronomical instrumentation as it covers the spectral range 3501050nm and is compact, rugged

  14. Coordinated observations of optical lightning from space using the FORTE photodiode detector and CCD imager

    Microsoft Academic Search

    D. M. Suszcynsky; T. E. Light; S. Davis; J. L. L. Guillen; W. Myre

    2001-01-01

    This paper presents an overview of the coordinated observation of optical lightning from space using the photodiode detector (PDD) and CCD-based imager known as the Lightning Location System (LLS) aboard the Fast On-Orbit Recording of Transient Events (FORTE) satellite. PDD\\/LLS coincidence statistics are presented and show that both the detected energy density and the detected peak irradiance of optical lightning

  15. Si:As BIB detector arrays

    NASA Technical Reports Server (NTRS)

    Bharat, R.; Petroff, M. D.; Speer, J. J.; Stapelbroek, M. G.

    1986-01-01

    Highlights of the results obtained on arsenic-doped silicon blocked impurity band (BIB) detectors and arrays since the invention of the BIB concept a few years ago are presented. After a brief introduction and a description of the BIB concept, data will be given on single detector performance. Then different arrays that were fabricated will be described and test data presented.

  16. Technique for mounting pyroelectric detector arrays

    NASA Technical Reports Server (NTRS)

    Breckenridge, R. A.; Fripp, A. L.; Robertson, J. B.

    1980-01-01

    Technique is developed at Langley Research Center for mounting pyroelectric detector arrays on silicon integrated circuits. Procedure incorporates normal silicon integrated-circuit technology to form quasi-free mounts for detector arrays. Advantages of technique include lower cost, better image registration, and improved reliability.

  17. Near Infrared Spectroscopic Imaging of NGC 7023 and Charge Trapping in Insb Photodiode Arrays

    NASA Astrophysics Data System (ADS)

    Solomon, Steven L.

    1998-09-01

    We have performed broadband and narrowband spectroscopic infrared imaging of the reflection nebula NGC7023 over the wavelengths 1.2-3.8?m. The dust composition varies widely across the face of the nebula. Both the 3.3?m and 3.4?m dust emission features are bright and variable across the nebula. The bright filaments in NGC7023 (1) are redder than the ambient nebula, (2) are self shielding, (3) have an 3.29?m line to continuum ratio of ~40, (4) show asymmetric spatial profiles and (5) exhibit a 3.4?m/3.29?m emission feature ratio of one half. A simple Hubble law analysis shows that scattered light is insufficient to account for this surface brightness. We have investigated the far infrared-3.29?m feature luminosity correlation in the context of NGC7023. HD200775, the central star of NGC7023, is the dominant radiative excitation source in the nebula. Of the seven stellar objects observed in the frame (excluding HD200775), two were found to be late-type main sequence stars and the remainder were hypothesized to be protostellar objects. We have demonstrated experimentally and theoretically that the latent image phenomenon in astronomical InSb photodiode infrared focal plane arrays passivated with SiOx can be explained by charge trapping at the front surface of the detector array. The type of front surface passivant and the electrical state of the surface both play crucial roles in determining the magnitude of this effect; SiOx exhibits significantly more image latency than does Si3N4. Behaviorally, the latent images are consistent with a modified Shockley, Read, Hall trapping model. The trap energies and cross sections were determined from experimental data; they are consistent with hole traps in the SiOx that lie within approximately 50A of the SiOx/InSb interface. Quantum mechanical tunneling was proposed as the mechanism for populating and depopulating the traps, and the molecular species In2O3 was advanced as a plausible candidate for the traps responsible for latent images in SiOx passivated InSb.

  18. Faraday Cup Detector Array with Electronic Interface

    Microsoft Academic Search

    Adi A. Scheidemann; Frank. J. Schumacher; Robert B. Darling; Arthur Isakharov; Patrick Jones

    2000-01-01

    A position sensitive Faraday cup detector array [FCDA] for ion beam detection has been developed. The FCDA is combined with an electronic multiplexing unit that allows collecting and integrating the charge deposited in the array and simultaneously reading out the same. The interface allows a duty cycle of > 98% for the position sensitive read-out, thus monitoring the entire array

  19. Apparatus and method for heterodyne-generated two-dimensional detector array using a single element detector

    DOEpatents

    Strauss, C.E.

    1997-11-18

    Apparatus and method are disclosed for heterodyne-generated, two-dimensional detector array using a single detector. Synthetic-array heterodyne detection, permits a single-element optical detector to behave as though it were divided into an array of separate heterodyne detector elements. A fifteen-element synthetic array has successfully been experimentally realized on a single-element detector, permitting all of the array elements to be read out continuously and in parallel from one electrical connection. A CO{sub 2} laser and a single-element HgCdTe photodiode are employed. A different heterodyne local oscillator frequency is incident upon the spatially resolvable regions of the detector surface. Thus, different regions are mapped to different heterodyne beat frequencies. One can determine where the photons were incident on the detector surface even though a single electrical connection to the detector is used. This also prevents the destructive interference that occurs when multiple speckles are imaged (similar to spatial diversity), In coherent LIDAR this permits a larger field of view. An acoustooptic modulator generates the local oscillator frequencies and can achieve adequate spatial separation of optical frequencies of the order of a megahertz apart. 4 figs.

  20. Apparatus and method for heterodyne-generated two-dimensional detector array using a single element detector

    DOEpatents

    Strauss, Charlie E. (Santa Fe, NM)

    1997-01-01

    Apparatus and method for heterodyne-generated, two-dimensional detector array using a single detector. Synthetic-array heterodyne detection, permits a single-element optical detector to behave as though it were divided into an array of separate heterodyne detector elements. A fifteen-element synthetic array has successfully been experimentally realized on a single-element detector, permitting all of the array elements to be read out continuously and in parallel from one electrical connection. A CO.sub.2 laser and a single-element HgCdTe photodiode are employed. A different heterodyne local oscillator frequency is incident upon the spatially resolvable regions of the detector surface. Thus, different regions are mapped to different heterodyne beat frequencies. One can determine where the photons were incident on the detector surface even though a single electrical connection to the detector is used. This also prevents the destructive interference that occurs when multiple speckles are imaged (similar to spatial diversity), In coherent LIDAR this permits a larger field of view. An acoustooptic modulator generates the local oscillator frequencies and can achieve adequate spatial separation of optical frequencies of the order of a megahertz apart.

  1. High-speed imaging and wavefront sensing with an infrared avalanche photodiode array

    E-print Network

    Baranec, Christoph; Riddle, Reed; Hall, Donald; Jacobson, Shane; Law, Nicholas M; Chun, Mark

    2015-01-01

    Infrared avalanche photodiode arrays represent a panacea for many branches of astronomy by enabling extremely low-noise, high-speed and even photon-counting measurements at near-infrared wavelengths. We recently demonstrated the use of an early engineering-grade infrared avalanche photodiode array that achieves a correlated double sampling read noise of 0.73 e- in the lab, and a total noise of 2.52 e- on sky, and supports simultaneous high-speed imaging and tip-tilt wavefront sensing with the Robo-AO visible-light laser adaptive optics system at the Palomar Observatory 1.5-m telescope. We report here on the improved image quality achieved simultaneously at visible and infrared wavelengths by using the array as part of an image stabilization control-loop with adaptive-optics sharpened guide stars. We also discuss a newly enabled survey of nearby late M-dwarf multiplicity as well as future uses of this technology in other adaptive optics and high-contrast imaging applications.

  2. Low temperature a-Si :H photodiodes and flexible image sensor arrays patterned by digital lithography

    NASA Astrophysics Data System (ADS)

    Ng, Tse Nga; Lujan, Rene A.; Sambandan, Sanjiv; Street, Robert A.; Limb, Scott; Wong, William S.

    2007-08-01

    Hydrogenated amorphous silicon-based image sensor arrays were fabricated on polyethylene naphthalate substrates, with photodiodes optimized for process temperatures of 150癈. An optimal i-layer thickness was determined to minimize carrier recombination and to maintain sufficient light absorption and acceptable leakage current. Patterning of the thin-film transistor backplane was accomplished using ink-jet printed etch masks. A flexible image sensor is demonstrated with 75dots/in. resolution over 180180pixels and with sensitivity of 1.2pW/cm2.

  3. Thermopile Detector Arrays for Space Science Applications

    NASA Technical Reports Server (NTRS)

    Foote, M. C.; Kenyon, M.; Krueger, T. R.; McCann, T. A.; Chacon, R.; Jones, E. W.; Dickie, M. R.; Schofield, J. T.; McCleese, D. J.; Gaalema, S.

    2004-01-01

    Thermopile detectors are widely used in uncooled applications where small numbers of detectors are required, particularly in low-cost commercial applications or applications requiring accurate radiometry. Arrays of thermopile detectors, however, have not been developed to the extent of uncooled bolometer and pyroelectric/ferroelectric arrays. Efforts at JPL seek to remedy this deficiency by developing high performance thin-film thermopile detectors in both linear and two-dimensional formats. The linear thermopile arrays are produced by bulk micromachining and wire bonded to separate CMOS readout electronic chips. Such arrays are currently being fabricated for the Mars Climate Sounder instrument, scheduled for launch in 2005. Progress is also described towards realizing a two-dimensional thermopile array built over CMOS readout circuitry in the substrate.

  4. Initial characterization of a position-sensitive photodiode/BGO detector for PET (positron emission tomography)

    SciTech Connect

    Derenzo, S.E.; Moses, W.W.; Jackson, H.G.; Turko, B.T.; Cahoon, J.L.; Geyer, A.B.; Vuletich, T.

    1988-11-01

    We present initial results of a position-sensitive photodiode/BGO detector for high resolution, multi-layer positron emission tomography (PET). Position sensitivity is achieved by dividing the 3 mm /times/ 20 mm rectangular photosensitive area along the diagonal to form two triangular segments. Each segment was individually connected to a low-noise amplifier. The photodiodes and crystals were cooled to /minus/100/degree/C to reduce dark current and increase the BGO signal. With an amplifier peaking time of 17 ..mu..sec, the sum of the signals (511 keV photopeak) was 3200 electrons with a full width at half maximum (fwhm) of 750 electrons. The ratio of one signal to the sum determined the depth of interaction with a resolution of 11 mm fwhm. 27 refs., 7 figs.

  5. MOCVD of bandgap-engineered HgCdTe p-n-N-P dual-band infrared detector arrays

    Microsoft Academic Search

    P. Mitra; S. L. Barnes; F. C. Case; M. B. Reine; P. O扗ette; R. Starr; A. Hairston; K. K黨ler; M. H. Weiler; B. L. Musicant

    1997-01-01

    We report the implementation of recent advances in metalorganic chemical vapor deposition (MOCVD) for in situ growth of four-layer HgCdTe mid wave\\/ long wave (MW\\/LW) simultaneous dual-band 64 ? 64 infrared detector arrays. This independently\\u000a accessed, simultaneous, double-heterojunction p-n-N-P dualband detector has two back-to-back stacked photodiodes grown on\\u000a CdZnTe (100) substrates. The LW photodiode is a p-on-n heterojunction grown on

  6. Low-Cost, Precision, Self-Alignment Technique for Coupling Laser and Photodiode Arrays to Polymer Waveguide Arrays on Multilayer PCBs

    Microsoft Academic Search

    Ioannis Papakonstantinou; David R. Selviah; Richard C. A. Pitwon; Dave Milward

    2008-01-01

    The first, to our knowledge, passive, precision, self-alignment technique for direct coupling of vertical cavity surface emitting laser (VCSEL) and photodiode (PD) arrays to an array of polymer buried channel waveguides on a rigid printed circuit board (PCB) is reported. It gives insertion losses as good as the best achieved previously, to within experimental measurement accuracy, but without the need

  7. Optoelectronic measurement for parameters of high-speed flying objects based on laser screen and photodiode array

    NASA Astrophysics Data System (ADS)

    Zhao, Donge; Zhang, Bin; Liu, Ji; Xiao, Kai-jia; Wang, Lei

    2013-09-01

    The impacting or penetrating power of high-speed flying object can be evaluated by its mass and velocity, so the velocity and the mass are two key parameters. Here we present an optoelectronic measurement method for parameters of high-speed flying objects based on parallel laser screen and photodiode array. The system consists of two thin laser screens with parallel each other and certain distance, orthogonal two dimensional photodiode arrays, data acquisition module, control module and data transmission processing module. When the object flies through the thin screen, the incident light of some photodiodes at the corresponding position is blocked and the output states of the corresponding photodiodes are changed. The flying position, which can be used to correct the distance error, velocity and the overall dimension of the object are determined by high-speed sampling and storing all the output states of photodiode array at any sampling moment when the object flying through the thin screens. We employed a line-shaped laser diode and a Fresnel lens with long-focal-length and aberration-free to generate parallel laser screen. The high-speed large-amount parallel data sampling module is comprised of four FPGA-based boards with built-in FIFO buffer memory, and the control module is constructed by one FPGA board and a FLASH memory. Functions simulation and experiment results of the FPGA-based data acquisition storage and the LabVIEW-based data processing indicate that the method and the design are feasible.

  8. Recent advances with mercuric iodide x-ray detectors and large-area silicon avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Dabrowski, Andrzej J.; Iwanczyk, Jan S.; Wang, Yuzhong J.; Madden, Michael C.; Szawlowski, Marek

    1993-10-01

    The paper presents advances in two sensor technologies: (1) Mercuric Iodide (HgI2) X-ray Detector Technology and, (2) Large Area Silicon Avalanche Photodiode (APD) Technology, which after years of development have recently produced commercially viable devices. Large Area Silicon Avalanche Photodiodes, which are solid-state light sensitive devices with internal amplification, combine the convenience, ruggedness and low power consumption of traditional semiconductor p-n and p-i-n photodiodes with the high light sensitivity and large photosensitive area approaching the active areas of traditional vacuum photomultiplier tubes. Device approaching 1-inch diameter with internal gain of up to 1000, have been developed by utilizing a beveled edge structure. By combining APD's with scintillation crystals, resolution of 6% (FWHM) was obtained for 662 keV energy line of 137Cs using a CsI(Tl) scintillator, and 7% (FWHM) was obtained using a NaI(Tl) scintillator. Resolution of 14% (FWHM) at room temperature and 11% (FWHM) at 0 degree(s)C have been obtained for APD's coupled to BGO scintillators. Rise times of 3 ns were measured by applying an impulse signal input, to a 200 mm2 device.

  9. Predictions of silicon avalanche photodiode detector performance in water vapor differential absorption lidar

    NASA Technical Reports Server (NTRS)

    Kenimer, R. L.

    1988-01-01

    Performance analyses are presented which establish that over most of the range of signals expected for a down-looking differential absorption lidar (DIAL) operated at 16 km the silicon avalanche photodiode (APD) is the preferred detector for DIAL measurements of atmospheric water vapor in the 730 nm spectral region. The higher quantum efficiency of the APD's, (0.8-0.9) compared to a photomultiplier's (0.04-0.18) more than offsets the higher noise of an APD receiver. In addition to offering lower noise and hence lower random error the APD's excellent linearity and impulse recovery minimize DIAL systematic errors attributable to the detector. Estimates of the effect of detector system parameters on overall random and systematic DIAL errors are presented, and performance predictions are supported by laboratory characterization data for an APD receiver system.

  10. DETECTOR ARRAYS FOR DIGITAL HOLOGRAPHIC STORAGE

    E-print Network

    Fossum, Eric R.

    ) and CMOS (complementary metal-oxide-semiconductor) active pixel sensors (APS). Both will be introduced and their relative merits presented. In fact, the CMOS APS, a much newer technology, will be shown to offer sensor array A 816x616 element, 17 m pixel pitch CMOS APS detector array designed for DHDS applications1

  11. High-resolution ionization detector and array of such detectors

    DOEpatents

    McGregor, Douglas S. (Ypsilanti, MI); Rojeski, Ronald A. (Pleasanton, CA)

    2001-01-16

    A high-resolution ionization detector and an array of such detectors are described which utilize a reference pattern of conductive or semiconductive material to form interaction, pervious and measurement regions in an ionization substrate of, for example, CdZnTe material. The ionization detector is a room temperature semiconductor radiation detector. Various geometries of such a detector and an array of such detectors produce room temperature operated gamma ray spectrometers with relatively high resolution. For example, a 1 cm.sup.3 detector is capable of measuring .sup.137 Cs 662 keV gamma rays with room temperature energy resolution approaching 2% at FWHM. Two major types of such detectors include a parallel strip semiconductor Frisch grid detector and the geometrically weighted trapezoid prism semiconductor Frisch grid detector. The geometrically weighted detector records room temperature (24.degree. C.) energy resolutions of 2.68% FWHM for .sup.137 Cs 662 keV gamma rays and 2.45% FWHM for .sup.60 Co 1.332 MeV gamma rays. The detectors perform well without any electronic pulse rejection, correction or compensation techniques. The devices operate at room temperature with simple commercially available NIM bin electronics and do not require special preamplifiers or cooling stages for good spectroscopic results.

  12. The LSO\\/APD array as a possible detector for in-beam PET in hadron therapy

    Microsoft Academic Search

    M. Kapusta; P. Crespo; D. Wolski; K. Heidel; L. Heinrich; J. Hutsch; J. Pawelke; M. Sobiella; A. Trzcinska; M. Moszynski; W. Enghardt

    2004-01-01

    We have studied the performance of finger-like LSO:Ce (LSO) crystals coupled one by one to pixels of avalanche photodiode detector (APD) arrays during their operation in coincidence at 12C ion beams of parameters being typical for tumor irradiations. In a first step of these experiments the parameters of the detectors and the signal processing setup have been characterized off-beam, i.e.,

  13. Characterization of madder and garancine in historic French red materials by liquid chromatography-photodiode array detection

    Microsoft Academic Search

    Guillaume Cuoco; Carole Mathe; Paul Archier; Cathy Vieillescazes

    2011-01-01

    A reverse phase liquid chromatography-photodiode array detection method is developed for the characterization of ancient samples of madder. In the past, modifications of the madder chemical composition were carried out by hydrolysing the plant dye precursors in order to increase its red power, the aim of this transformation being to concentrate the red colour of the matter. After extraction of

  14. Modeling Charge Collection in Detector Arrays

    NASA Technical Reports Server (NTRS)

    Hardage, Donna (Technical Monitor); Pickel, J. C.

    2003-01-01

    A detector array charge collection model has been developed for use as an engineering tool to aid in the design of optical sensor missions for operation in the space radiation environment. This model is an enhancement of the prototype array charge collection model that was developed for the Next Generation Space Telescope (NGST) program. The primary enhancements were accounting for drift-assisted diffusion by Monte Carlo modeling techniques and implementing the modeling approaches in a windows-based code. The modeling is concerned with integrated charge collection within discrete pixels in the focal plane array (FPA), with high fidelity spatial resolution. It is applicable to all detector geometries including monolithc charge coupled devices (CCDs), Active Pixel Sensors (APS) and hybrid FPA geometries based on a detector array bump-bonded to a readout integrated circuit (ROIC).

  15. A multi-element detector array for heavy fragments emitted in intermediate energy nuclear reactions

    NASA Astrophysics Data System (ADS)

    Iori, I.; Manduci, L.; Moroni, A.; Scardaoni, R.; Chongwen, Sun; Yuzhao, Zhang; Guangming, Zhang; Giglio, F.; Mora, E.; di Pietro, G.; Dellera, L.; Cortesi, A.; Bassini, R.; Boiano, C.; Brambilla, S.; Malatesta, M.; Bruno, M.; D'Agostino, M.; Fiandri, M. L.; Fuschini, E.; Milazzo, P. M.; Busacchi, G.; Cunsolo, A.; Foti, A.; Gianino, C.; Sava, G.; Gramegna, F.; Buttazzo, P.; Margagliotti, G. V.; Vannini, G.; Auger, G.; Plagnol, E.

    1993-02-01

    To investigate complex fragment emission in intermediate energy nucleus-nucleus collisions, an array of three-element telescopes has been constructed. The array is designed to measure energy, charge and emission angles of fragments with Z values from 2 up to the projectile atomic number when studying reactions in reverse kinematics. In this case it has a good efficiency even for events with complex fragment high multiplicity. Each telescope is made of an ionization chamber (filled with CF4 at a pressure up to 300 mbar), a Si detector (500 ?m thick, position sensitive in two dimensions) and a CsI(Tl) scintillator with photodiode readout.

  16. Signal-to-noise ratio of Geiger-mode avalanche photodiode single-photon counting detectors

    NASA Astrophysics Data System (ADS)

    Kolb, Kimberly

    2014-08-01

    Geiger-mode avalanche photodiodes (GM-APDs) use the avalanche mechanism of semiconductors to amplify signals in individual pixels. With proper thresholding, a pixel will be either "on" (avalanching) or "off." This discrete detection scheme eliminates read noise, which makes these devices capable of counting single photons. Using these detectors for imaging applications requires a well-developed and comprehensive expression for the expected signal-to-noise ratio (SNR). This paper derives the expected SNR of a GM-APD detector in gated operation based on gate length, number of samples, signal flux, dark count rate, photon detection efficiency, and afterpulsing probability. To verify the theoretical results, carrier-level Monte Carlo simulation results are compared to the derived equations and found to be in good agreement.

  17. Profiling and Quantitation of Bacterial Carotenoids by Liquid Chromatography and Photodiode Array Detection

    PubMed Central

    Nelis, H. J.; De Leenheer, A. P.

    1989-01-01

    An analytical method for the profiling and quantitative determination of carotenoids in bacteria is described. Exhaustive extraction of the pigments from four selected bacterial strains required treatment of the cells with potassium hydroxide or liquefied phenol or both before the addition of the extracting solvent (methanol or diethyl ether). The carotenoids in the extracts were separated by nonaqueous reversed-phase liquid chromatography in conjunction with photodiode array absorption detection. The identity of a peak was considered definitive only when both its retention time and absorption spectrum, before and after chemical reactions, matched those of a reference component. In the absence of the latter, most peaks could be tentatively identified. Two examples illustrate how in the analysis of pigmented bacteria errors may result from using nonchromatographic procedures or liquid chromatographic methods lacking sufficient criteria for peak identification. Carotenoids of interest were determined quantitatively when the authentic reference substance was available or, alternatively, were determined semiquantitatively. PMID:16348068

  18. Measurement of impurity emission profiles in CHS Plasma using AXUV photodiode arrays and VUV bandpass filters

    NASA Astrophysics Data System (ADS)

    Suzuki, C.; Peterson, B. J.; Ida, K.

    2004-10-01

    We have designed a compact and low-cost diagnostic system for spatiotemporal distributions of specific vacuum ultraviolet (VUV) emission lines from impurities in Compact Helical System (CHS) plasmas. The system consists of 20 channel absolute extreme ultraviolet photodiode arrays combined with interchangeable thin foil filters which have passbands in the VUV region. A compact mounting module which contains all the components including an in-vacuum preamplifier for immediate current-voltage conversion has been designed and successfully fabricated. A preliminary measurement with a single module using an aluminum foil filter has been carried out for monitoring the behavior of oxygen impurity in CHS, and initial results have been obtained. Two identical modules equipped with Versa Module European bus-based analog-digital converters will be available for future tomographic measurements.

  19. Simultaneous determination of seven lignans in Justicia procumbens by high performance liquid chromatography-photodiode array detection using relative response factors.

    PubMed

    Luo, Zuliang; Kong, Weijun; Qiu, Feng; Yang, Meihua; Li, Qian; Wei, Riwei; Yang, Xiaoli; Qin, Jieping

    2013-02-01

    A simple and sensitive HPLC coupled with photodiode array (HPLC-PDA) method was developed for simultaneous determination of seven lignans in Justicia procumbens using relative response factors (RRFs). The chromatographic separation was performed on a Shiseido Capcell Pak C(18) column (250 4.6 mm id, 5 ?m), a gradient elution of acetonitrile/water, and a photodiode array detector. The column temperature was maintained at 35癈 and the detection wavelength was set at 256 nm. Chinensinaphthol methyl ether was selected as the reference compound for calculating the relative response factors of the lignans. It has shown that the RRFs for lignans are quite similar at 256 nm of detection under different analytical conditions (different columns and HPLC instruments). Using RRFs, not every lignan is needed as a reference standard, making the method ideal for rapid, routine analysis, especially for those laboratories where lignans standards are not readily available. An economic and practicable HPLC method using RRFs was established for the determination of seven lignans in J. procumbens. This method not only can determine multiple indexes in traditional Chinese medicines (TCMs) simultaneously, but also resolve the problem of lacking of chemical standards. It will be a good quality evaluation method and pattern for TCMs. PMID:23355351

  20. Energy resolution of scintillation detectors readout with large area avalanche photodiodes and photomultipliers

    SciTech Connect

    Moszynski, M.; Wolski, D. [Soltan Inst. for Nuclear Studies, Swierk-Otwock (Poland)] [Soltan Inst. for Nuclear Studies, Swierk-Otwock (Poland); Kapusta, M. [Soltan Inst. for Nuclear Studies, Swierk-Otwock (Poland)] [Soltan Inst. for Nuclear Studies, Swierk-Otwock (Poland); [Univ. of Warsaw (Poland). Inst. of Experimental Physics; Szawlowski, M. [Advanced Photonix, Inc., Camarillo, CA (United States)] [Advanced Photonix, Inc., Camarillo, CA (United States); Klamra, W. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Physics] [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Physics

    1998-06-01

    The energy resolution of small NaI(Tl), CsI(Tl), BGO, GSO, YAP and LSO crystals has been studied using 16 mm diameter large area avalanche photodiodes (LAAPD) and a 52 mm diameter photomultiplier. The best result of 4.8% for 662 keV {gamma}-rays from a {sup 137}Cs source was obtained with a 9 mm in diameter by 9 mm high CsI(Tl) scintillator coupled to an LAAPD. Measuring the number of primary electron-hole pairs produced in the LAAPD and photoelectrons in the photomultiplier, as well as the noise contribution of the LAAPD, allowed a quantitative discussion of the results. The energy resolutions measured with LAAPDs are comparable to, or significantly better (at certain emission wavelengths) than, those obtained with the photomultiplier. At energies above 100 keV the energy resolution measured with the majority of crystals and the LAAPD was weakly affected by the photodiode noise contribution. The advantages and limitations of LAAPDs in energy spectrometry with scintillation detectors are also discussed.

  1. The particle detector array AMPHORA

    Microsoft Academic Search

    D. Drain; A. Giorni; D. Hilscher; C. Ristori; J. Alarja; G. Barbier; R. Bertholet; R. Billerey; B. Chambon; B. Cheynis; J. Cran鏾n; A. Dauchy; P. D閟esquelles; A. Fontenille; L. Guyon; D. Heuer; A. Ll鑢es; M. Maurel; E. Monnand; C. Morand; H. Nifenecker; C. Pastor; J. Pouxe; H. Rossner; J. Saint-Martin; F. Schussler; P. Stassi; M. Tournier; J. B. Viano

    1989-01-01

    A 4pi-multidetector consisting of 140 CsI(Tl) detectors has been designed and built to be used for detecting and identifying either light charged particles (with a detection threshold of about 0.4 MeV\\/nucleon) and neutrons or light heavy ions and light charged particles, in the range of energies available at SARA (from 10 to 40 MeV\\/nucleon). The choice of the scintillator material

  2. A small animal PET prototype based on LSO crystals read out by avalanche photodiodes

    Microsoft Academic Search

    O. Fries; S. M. Bradbury; J. Gebauer; I. Holl; E. Lorenz; D. Renker; S. I. Ziegler

    1997-01-01

    Feasibility studies of modern avalanche photodiodes (APDs), coupled to LSO scintillation crystals, have given encouraging results for new detector designs in positron emission tomography (PET). We constructed an experimental set-up for measuring the performance of new arrays of 2 8 detector channels of APD\\/LSO. This gantry allows us to simulate a complete ring of these array detectors and will

  3. Signal processing for an infrared array detector

    SciTech Connect

    Young, M.A.; Smith, G.E.; Pimentel, G.C. (Laboratory of Chemical Biodynamics, Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 (US))

    1989-09-01

    A broadband detection scheme for a time-resolved infrared absorption spectrometer, based on a multielement mercury-cadmium-telluride (MCT) array, has been successfully implemented. The spectrometer achieves a resolution on the 10-ns time scale despite the much larger time constant characteristic of the MCT elements. Our signal-collection circuitry takes advantage of the slow decay by integrating the detector response to pulsed IR radiation. The dynamic range is 100--1 and the resultant noise level is near the detector limit. Data acquisition for the 120 elements is fast enough to allow scan rates of 30--40 Hz. The completed electronics are sufficiently compact to be situated local to the array detector, and the design is relatively inexpensive to construct using commonly found electronic components.

  4. Measurement of 膊睷n diffusion through sandy soil with solar cells photodiodes as the detector.

    PubMed

    Shitrit, Y; Dody, A; Alfassi, Z B; Berant, Z

    2012-02-01

    An experimental system was developed to study the diffusion rate of radon (膊睷n) gas through porous media as a function of soil porosity/grain size and soil water content. Columns with different grain sizes, soil water content and soil depths were used. The system used solar cells photodiodes as alpha (?) detectors. This new detector is highly efficient and low cost compared to other known detectors. Soil water content was found to be the most dominant factor affecting the 膊睷n diffusion rate. A maximum diffusion rate value of (6.5 0.07) 10?? m/s was found in dry conditions. The minimum diffusion value of less than (3.9 0.14) 10?? m/s was found in 2% soil water content. The experimental results were compared with theoretical calculations done with the "GREEN equation". Two discrepancies were observed: the time to equilibrium state in the measurements was longer compare to the calculated values and the ? count rates were lower in the experiment compared with the theoretical calculations. These results can be explained by the differences in the system geometry. PMID:22230015

  5. Optimal design of a generalized compound eye particle detector array

    E-print Network

    Nehorai, Arye

    Optimal design of a generalized compound eye particle detector array Arye Nehoraia, Zhi Liua ABSTRACT We analyze the performance of a novel detector array1 for detecting and localizing particle shape with a lens on top and a particle detectors subarray inside. The array's configuration is inspired

  6. Spatial resolution and depth-of-interaction studies with a PET detector module composed of LSO and an APD array

    Microsoft Academic Search

    An A. R. Fremout; Ruru Chen; Peter Bruyndonckx; Stefaan P. K. Tavernier

    2002-01-01

    Detailed results are given for the study of the spatial resolution obtained with different configurations of lutetium oxyorthosilicate (LSO) scintillation crystals read out by a Hamamatsu 2 8 avalanche photodiode (APD) array. Block detectors as well as small-sized individual LSO crystals have been coupled to the APD matrix. Both one-to-one coupling and light-sharing schemes were investigated. The spatial resolution

  7. MOCVD of bandgap-engineered HgCdTe p-n-N-P dual-band infrared detector arrays

    NASA Astrophysics Data System (ADS)

    Mitra, P.; Barnes, S. L.; Case, F. C.; Reine, M. B.; O'Dette, P.; Starr, R.; Hairston, A.; K黨ler, K.; Weiler, M. H.; Musicant, B. L.

    1997-06-01

    We report the implementation of recent advances in metalorganic chemical vapor deposition (MOCVD) for in situ growth of four-layer HgCdTe mid wave/ long wave (MW/LW) simultaneous dual-band 64 64 infrared detector arrays. This independently accessed, simultaneous, double-heterojunction p-n-N-P dualband detector has two back-to-back stacked photodiodes grown on CdZnTe (100) substrates. The LW photodiode is a p-on-n heterojunction grown on top of an MW N-on-P heterojunction photodiode. Secondary ion mass spectrometry depth profiles of these 28 m thick p-n-N-P dual-band films show four well-defined regions of alloy composition and doping, and agree well with the device design. 64 64 arrays of dual-band detectors were fabricated from these films using electron cyclotron resonance dry etching and CdTe passivation, and hybridized to a dual-band readout chip. Two bump inter-connects in each unit cell provide independent electrical access to the back-to-back MW and LW photodiodes, and allow the MW and LW photocurrents to be separate and independent. The dualband infrared focal plane arrays (IRFPAs) spectral response data at 78K are well-behaved and are fully consistent with that observed in individual singleband LW p-on-n and MW N-on-P heterojunction devices of the same design. The hybridized 64 64 duai-band FPAs have MW and LW average in-band quantum efficiencies of 79 and 67%, and median D* values of 4.8 1011 and 7.1 1010 cm-?Hz/W, in the respective spectral bands at 78K. The data demonstrate that MOCVD has progressed significantly toward being a practical and viable vapor phase in situ growth technology for advanced bandgap-engineered HgCdTe detector arrays.

  8. Development of the ORRUBA Silicon Detector Array

    SciTech Connect

    Pain, S. D. [Rutgers University; Bardayan, Daniel W [ORNL; Blackmon, Jeff C [ORNL; Chae, K. Y. [University of Tennessee, Knoxville (UTK); Chipps, K. [Colorado School of Mines, Golden; Cizewski, J. A. [Rutgers University; Hatarik, Robert [Rutgers University; Johnson, M. S. [Oak Ridge Associated Universities (ORAU); Jones, K. L. [University of Tennessee, Knoxville (UTK); Kapler, R. [University of Tennessee, Knoxville (UTK); Kozub, R. L. [Tennessee Technological University; Matei, Catalin [Oak Ridge Associated Universities (ORAU); Moazen, Brian [University of Tennessee, Knoxville (UTK); Nesaraja, Caroline D [ORNL; O'Malley, Patrick [Rutgers University; Smith, Michael Scott [ORNL; Thomas, J. S. [Rutgers University

    2009-01-01

    High quality radioactive beams have recently made possible the measurement of (d,p) reactions on unstable nuclei in inverse kinematics, which can yield information on the development of single-neutron structure away from stability, and are of astrophysical interest due to the proximity to suggested r-process paths. The Oak Ridge Rutgers University Barrel Array (ORRUBA) is a new high solid-angular coverage array, composed of two rings of silicon detectors, optimized for measuring (d,p) reactions. A partial implementation has been used to measure (d,p) reactions on nuclei around the N = 82 shell closure.

  9. Supercritical fluid chromatography with photodiode array detection for pesticide analysis in papaya and avocado samples.

    PubMed

    Pano-Farias, Norma S; Ceballos-Maga馻, Silvia G; Gonzalez, Jorge; Jurado, Jos M; Mu駃z-Valencia, Roberto

    2015-04-01

    To improve the analysis of pesticides in complex food matrices with economic importance, alternative chromatographic techniques, such as supercritical fluid chromatography, can be used. Supercritical fluid chromatography has barely been applied for pesticide analysis in food matrices. In this paper, an analytical method using supercritical fluid chromatography coupled to a photodiode array detection has been established for the first time for the quantification of pesticides in papaya and avocado. The extraction of methyl parathion, atrazine, ametryn, carbofuran, and carbaryl was performed through the quick, easy, cheap, effective, rugged, and safe methodology. The method was validated using papaya and avocado samples. For papaya, the correlation coefficient values were higher than 0.99; limits of detection and quantification ranged from 130-380 and 220-640 ?g/kg, respectively; recovery values ranged from 72.8-94.6%; precision was lower than 3%. For avocado, limit of detection values were ?450 ?g/kg; precision was lower than 11%; recoveries ranged from 50.0-94.2%. Method feasibility was tested for lime, banana, mango, and melon samples. Our results demonstrate that the proposed method is applicable to methyl parathion, atrazine, ametryn, and carbaryl, toxics pesticides used worldwide. The methodology presented in this work could be applicable to other fruits. PMID:25641906

  10. Single-Photon-Sensitive HgCdTe Avalanche Photodiode Detector

    NASA Technical Reports Server (NTRS)

    Huntington, Andrew

    2013-01-01

    The purpose of this program was to develop single-photon-sensitive short-wavelength infrared (SWIR) and mid-wavelength infrared (MWIR) avalanche photodiode (APD) receivers based on linear-mode HgCdTe APDs, for application by NASA in light detection and ranging (lidar) sensors. Linear-mode photon-counting APDs are desired for lidar because they have a shorter pixel dead time than Geiger APDs, and can detect sequential pulse returns from multiple objects that are closely spaced in range. Linear-mode APDs can also measure photon number, which Geiger APDs cannot, adding an extra dimension to lidar scene data for multi-photon returns. High-gain APDs with low multiplication noise are required for efficient linear-mode detection of single photons because of APD gain statistics -- a low-excess-noise APD will generate detectible current pulses from single photon input at a much higher rate of occurrence than will a noisy APD operated at the same average gain. MWIR and LWIR electron-avalanche HgCdTe APDs have been shown to operate in linear mode at high average avalanche gain (M > 1000) without excess multiplication noise (F = 1), and are therefore very good candidates for linear-mode photon counting. However, detectors fashioned from these narrow-bandgap alloys require aggressive cooling to control thermal dark current. Wider-bandgap SWIR HgCdTe APDs were investigated in this program as a strategy to reduce detector cooling requirements.

  11. Signal processing for an infrared array detector

    Microsoft Academic Search

    M. A. Young; G. E. Smith; G. C. Pimentel

    1989-01-01

    A broadband detection scheme for a time-resolved infrared absorption spectrometer, based on a multielement mercury-cadmium-telluride (MCT) array, has been successfully implemented. The spectrometer achieves a resolution on the 10-ns time scale despite the much larger time constant characteristic of the MCT elements. Our signal-collection circuitry takes advantage of the slow decay by integrating the detector response to pulsed IR radiation.

  12. Thick, segmented CdWO{sub 4}-photodiode detector for cone beam megavoltage CT: A Monte Carlo study of system design parameters

    SciTech Connect

    Monajemi, T. T.; Fallone, B. G.; Rathee, S. [Department of Medical Physics, Cross Cancer Institute, University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada) and Departments of Oncology and Physics, University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada); Department of Medical Physics, Cross Cancer Institute, University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada) and Department of Oncology, University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada)

    2006-12-15

    Megavoltage (MV) imaging detectors have been the focus of research by many groups in recent years. We have been working with segmented CdWO{sub 4} crystals in contact with photodiodes in our lab. The present study uses both x-ray and optical photon transport Monte Carlo simulations to analyze the effects of scintillation crystal height, septa material, beam divergence, and beam spectrum on the modulation transfer function, MTF(f) and zero frequency detective quantum efficiency, DQE(0), of a theoretical area detector. The theoretical detector is comprised of tall, segmented CdWO{sub 4} crystals and two dimensional photodiode arrays with a pitch of 1 mm and a fill factor of 72%. Increasing the crystal height above 10 mm does not result in an improvement in the DQE(0) if the reflection coefficient of the septa is less than 0.8. For a reflection coefficient of 0.975 for the septa, there is a continual gain in the DQE(0) up to 30 mm tall crystals. Similar calculations show that employing a 3.5 MV beam without a flattening filter increases the DQE(0) for 20 mm tall crystals by 9% compared to a typical 6 MV beam with a flattening filter. The severe degradations due to beam divergence on MTF(f) are quantified and suggest the use of focused detectors in MV imaging. It is found that when the effect of optical photons is considered, the presence of divergence can appear as a shift in the location of the input signal as well as loss of spatial resolution.

  13. Adaptive Detector Arrays for Optical Communications Receivers

    NASA Technical Reports Server (NTRS)

    Vilnrotter, V.; Srinivasan, M.

    2000-01-01

    The structure of an optimal adaptive array receiver for ground-based optical communications is described and its performance investigated. Kolmogorov phase screen simulations are used to model the sample functions of the focal-plane signal distribution due to turbulence and to generate realistic spatial distributions of the received optical field. This novel array detector concept reduces interference from background radiation by effectively assigning higher confidence levels at each instant of time to those detector elements that contain significant signal energy and suppressing those that do not. A simpler suboptimum structure that replaces the continuous weighting function of the optimal receiver by a hard decision on the selection of the signal detector elements also is described and evaluated. Approximations and bounds to the error probability are derived and compared with the exact calculations and receiver simulation results. It is shown that, for photon-counting receivers observing Poisson-distributed signals, performance improvements of approximately 5 dB can be obtained over conventional single-detector photon-counting receivers, when operating in high background environments.

  14. Heterojunction model for Focal Plane Array detector devices

    Microsoft Academic Search

    Glenn T. Hess; Thomas J. Sanders; Hang-Ming Dai; Gwendolyn Newsome; Theodore Fischer

    1997-01-01

    Night vision systems for military and commercial applications usually use an Infrared Focal Plane Array (IRFPA) for its radiation detector. Existing IRFPA models lack simplicity for setting up the detector's architecture\\/structure and lack continuity between IR detector material, IR detector processes and detector architecture. This paper will discuss the first version a new IRFPA computer model which is to be

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

    NASA Astrophysics Data System (ADS)

    Baptista, Brian

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

  16. Schottky type photodiodes as detectors in the VUV and soft x-ray range.

    PubMed

    Krumrey, M; Tegeler, E; Barth, J; Krisch, M; Sch鋐ers, F; Wolf, R

    1988-10-15

    The quantum efficiencies of semiconductor photodiodes have been measured at photon energies from 5 to 3500 eV. For silicon photodiodes strong radiation-induced effects were found. GaAsP and GaP Schottky diodes show remarkable stability and high quantum efficiency. Use of Schottky diodes for spectroscopic and radiometric measurements is discussed. PMID:20539564

  17. A silicon avalanche photodiode detector circuit for Nd:YAG laser scattering

    SciTech Connect

    Hsieh, C.L.; Haskovec, J.; Carlstrom, T.N.; DeBoo, J.C.; Greenfield, C.M.; Snider, R.T.; Trost, P.

    1990-06-01

    A silicon avalanche photodiode with an internal gain of about 50 to 100 is used in a temperature controlled environment to measure the Nd:YAG laser Thomson scattered spectrum in the wavelength range from 700 to 1150 nm. A charge sensitive preamplifier has been developed for minimizing the noise contribution from the detector electronics. Signal levels as low as 20 photoelectrons (S/N = 1) can be detected. Measurements show that both the signal and the variance of the signal vary linearly with the input light level over the range of interest, indicating Poisson statistics. The signal is processed using a 100 ns delay line and a differential amplifier which subtracts the low frequency background light component. The background signal is amplified with a computer controlled variable gain amplifier and is used for an estimate of the measurement error, calibration, and Z{sub eff} measurements of the plasma. The signal processing has been analyzed using a theoretical model to aid the system design and establish the procedure for data error analysis. 4 refs., 5 figs.

  18. A large-area monolithic array of silicon drift detectors for medical imaging

    NASA Astrophysics Data System (ADS)

    Fiorini, C.; Gola, A.; Longoni, A.; Zanchi, M.; Restelli, A.; Perotti, F.; Lechner, P.; Soltau, H.; Str黡er, L.

    2006-11-01

    Monolithic arrays of silicon drift detectors (SDDs) have been recently proposed to be used with scintillators for high-position-resolution ?-ray imaging applications. Thanks to the low electronics noise due to the small value of the output capacitance, the SDD offers better noise performances with respect to conventional photodiodes of the same geometry. Small monolithic arrays of SDDs have been used as photodetector of the scintillation light in a first prototype of Anger Camera for ?-ray imaging characterized by an intrinsic resolution better than 0.3 mm. In this work, we present a new large-area monolithic array of SDDs. It consists of a single chip composed of 77 single hexagonal units, each one with an active area of 8.7 mm 2, for a total active area of the device of 6.7 cm 2. It represents the largest monolithic array of SDDs with on-chip JFETs produced up to now for X-ray and ?-ray detection. The results achieved in the experimental characterization of a first prototype of the detector array are presented, both with X and visible photons. The energy resolution measured at 6 keV with the single unit of the array is of 142 eV at -10 癈, while a QE>90% was measured at ?=550 nm.

  19. Astronomical imaging with infrared array detectors.

    PubMed

    Gatley, I; Depoy, D L; Fowler, A M

    1988-12-01

    History shows that progress in astronomy often stems directly from technological innovation and that each portion of the electromagnetic spectrum offers unique insights into the nature of the universe. Most recently, the widespread availability of infrared-sensitive two-dimensional array detectors has led to dramatic improvements in the capabilities of conventional ground-based observatories. The impact of this new technology on our understanding of a wide variety of phenomena is illustrated here by infrared pictures of star-forming regions, of nebulae produced by the late stages of stellar evolution, of the nucleus of our own galaxy(the Milky Way), and of activity in other galaxies. PMID:17817072

  20. Fingerprint analysis of fruiting bodies of cultured Cordyceps militaris by high-performance liquid chromatography-photodiode array detection.

    PubMed

    Yu, Rongmin; Ye, Bin; Yan, Chunyan; Song, Liyan; Zhang, Zhang; Yang, Wei; Zhao, Yu

    2007-07-27

    We have developed and optimized a novel, efficient and accurate fingerprint method using high-performance liquid chromatography-photodiode array detection (HPLC-DAD) for the quality control of cultured Cordyceps militaris (L.) Link. The feasibility and advantages of the used chromatographic fingerprint were verified for the evaluation of cultured C. militaris by systematically comparing chromatograms with a professional analytical software recommended by State Food and Drug Administration (SFDA) of PR China. The results revealed that the chromatographic fingerprint combining similarity evaluation could efficiently identify and distinguish cultured C. militaris from different sources. PMID:17512693

  1. Linear arrays of InGaAs/InP avalanche photodiodes for 1.0-1.7 micron

    NASA Technical Reports Server (NTRS)

    Ackley, D. E.; Hladky, J.; Lange, M. J.; Mason, S.; Erickson, G.; Olsen, G. H.; Ban, V. S.; Forrest, S. R.; Staller, C.

    1990-01-01

    Separate absorption and multiplication InGaAs/InP avalanche photodiodes (SAM-APDs) with a floating guard ring structure that is well-suited to array applications have been successfully demonstrated. Individual APDs have breakdown voltages greater than 80 V, multiplications over 40 at 100 nA dark current, and uniform spatial gain profiles. Uniform I-V characteristics and gains have been measured over linear dimensions as large as 1.2 cm. Gains over 10 at low multiplied dark currents were measured on 21 consecutive devices at the wafer level.

  2. Design of a high sensitivity emitter-detector avalanche photodiode imager using very high transmittance, back-illuminated, silicon-on-sapphire

    NASA Astrophysics Data System (ADS)

    Stern, Alvin G.

    2012-06-01

    We present a detailed design study for a novel solid-state focal plane array of silicon avalanche photodiodes (APDs) using an advanced silicon-on-sapphire substrate incorporating an antireflective bilayer consisting of crystalline aluminum nitride (AlN) and amorphous, non-stoichiometric, silicon rich, silicon nitride (a-SiNX<1.33) between the silicon and sapphire. The substrate supports electrical and optical integration of a nearly 100% quantum efficiency, silicon APD capable of operating with wide dynamic range in dual linear or Geiger-mode, with a gallium nitride (GaN) laser diode in each pixel. The APD device and epitaxially grown GaN laser are fabricated within a crystallographically etched silicon mesa. The high resolution 27 ?m emitter-detector pixel design enables single photon sensitive, solid-state focal plane arrays (FPAs), with passive and active imaging capability in a single FPA. The square 27 ?m emitter-detector pixel achieves SNR>10 in active detection mode for Lambert surfaces at 20,000 m.

  3. Double-Layer Silicon PIN Photodiode X-Ray Detector for a Future X-ray Timing Mission

    E-print Network

    Hua Feng; Philip Kaaret; Hans Andersson

    2006-06-01

    A double-layer silicon detector consisting of two 500micron-thick silicon PIN photodiodes with independent readouts was mounted in a vacuum chamber and tested with X-ray sources. The detector is sensitive from 1-30 keV with an effective area of 6 mm^2. The detector performs best at -35 C with an energy resolution of 220 eV (FWHM, full width at half maximum) at 5.9 keV, and is able to operate at room temperature, +25 C, with moderate resolution around 760 eV (FWHM). The response of the top layer sensor is highly uniform across the sensitive area. This large-format silicon detector is appropriate for future X-ray timing missions.

  4. A novel, SiPM-array-based, monolithic scintillator detector for PET.

    PubMed

    Schaart, Dennis R; van Dam, Herman T; Seifert, Stefan; Vinke, Ruud; Dendooven, Peter; L鰄ner, Herbert; Beekman, Freek J

    2009-06-01

    Silicon photomultipliers (SiPMs) are of great interest to positron emission tomography (PET), as they enable new detector geometries, for e.g., depth-of-interaction (DOI) determination, are MR compatible, and offer faster response and higher gain than other solid-state photosensors such as avalanche photodiodes. Here we present a novel detector design with DOI correction, in which a position-sensitive SiPM array is used to read out a monolithic scintillator. Initial characterization of a prototype detector consisting of a 4 x 4 SiPM array coupled to either the front or back surface of a 13.2 mm x 13.2 mm x 10 mm LYSO:Ce(3+) crystal shows that front-side readout results in significantly better performance than conventional back-side readout. Spatial resolutions <1.6 mm full-width-at-half-maximum (FWHM) were measured at the detector centre in response to an approximately 0.54 mm FWHM diameter test beam. Hardly any resolution losses were observed at angles of incidence up to 45 degrees , demonstrating excellent DOI correction. About 14% FWHM energy resolution was obtained. The timing resolution, measured in coincidence with a BaF(2) detector, equals 960 ps FWHM. PMID:19443953

  5. Assessment of HgCdTe photodiodes and quantum well infrared photoconductors for long wavelength focal plane arrays

    Microsoft Academic Search

    Antoni Rogalski

    1999-01-01

    Recent trends in infrared detectors are towards large, electronically addressed two-dimensional arrays. In the long wavelength infrared (LWIR) spectral range HgCdTe focal plane arrays (FPAs) occupy a dominant position. However, the slow progress in the development of large LWIR photovoltaic HgCdTe infrared imaging arrays and the rapid achievements of novel semiconductor heterostructure systems have made it necessary to foresee the

  6. A LSO scintillator array for a PET detector module with depth of interaction measurement

    SciTech Connect

    Huber, J.S.; Moses, W.W.; Andreaco, M.S.; Petterson, O.

    2000-10-30

    We present construction methods and performance results for a production scintillator array of 64 optically isolated, 3 mm x 3 mm x 30 mm sized LSO crystals. This scintillator array has been developed for a PET detector module consisting of the 8x8 LSO array coupled on one end to a single photomultiplier tube (PMT) and on the opposite end to a 64 pixel array of silicon photodiodes (PD). The PMT provides an accurate timing pulse and initial energy discrimination, the PD identifies the crystal of interaction, the sum provides a total energy signal, and the PD/(PD+PMT) ratio determines the depth of interaction (DOI). Unlike the previous LSO array prototypes, we now glue Lumirror reflector material directly onto 4 sides of each crystal to obtain an easily manufactured, mechanically rugged array with our desired depth dependence. With 511 keV excitation, we obtain a total energy signal of 3600 electrons, pulse-height resolution of 25% fwhm, and 6-15 mm fwhm DOI resolution.

  7. Development of a (Hg, Cd)Te photodiode detector, Phase 2. [for 10.6 micron spectral region

    NASA Technical Reports Server (NTRS)

    1972-01-01

    High speed sensitive (Hg,Cd)Te photodiode detectors operating in the 77 to 90 K temperature range have been developed for the 10.6 micron spectral region. P-N junctions formed by impurity (gold) diffusion in p-type (Hg, Cd) Te have been investigated. It is shown that the bandwidth and quantum efficiency of a diode are a constant for a fixed ratio of mobility/lifetime ratio of minority carriers. The minority carrier mobility and lifetime uniquely determine the bandwidth and quantum efficiency and indicate the shallow n on p (Hg,Cd) Te diodes are preferable as high performance, high frequency devices.

  8. Housing for an ionization detector array in a tomographic scanner

    Microsoft Academic Search

    B. D. Peerenboom; K. L. Sypal

    1984-01-01

    An improved housing construction for electrical apparatus is disclosed, the housing having particular utility as a housing suitable for an ionization detector array of a tomographic X-ray scanner. The housing comprises at least two mating sections which, upon assembly and juxtaposition one to another, form a closed interior chamber adapted to receive the detector array, or other electrical apparatus. A

  9. The Impact of Array Detectors on Raman Spectroscopy

    ERIC Educational Resources Information Center

    Denson, Stephen C.; Pommier, Carolyn J. S.; Denton, M. Bonner

    2007-01-01

    The impact of array detectors in the field of Raman spectroscopy and all low-light-level spectroscopic techniques is examined. The high sensitivity of array detectors has allowed Raman spectroscopy to be used to detect compounds at part per million concentrations and to perform Raman analyses at advantageous wavelengths.

  10. Organic non-volatile resistive photo-switches for flexible image detector arrays.

    PubMed

    Nau, Sebastian; Wolf, Christoph; Sax, Stefan; List-Kratochvil, Emil J W

    2015-02-01

    A unique implementation of an organic image detector using resistive photo-switchable pixels is presented. This resistive photo-switch comprises the vertical integration of an organic photodiode and an organic resistive switching memory element. The photodiodes act as a photosensitive element while the resistive switching elements simultaneously store the detected light information. PMID:25534514

  11. Popcorn noise in linear In0.53Ga0.47As detector arrays

    NASA Astrophysics Data System (ADS)

    Joshi, Abhay M.; Olsen, Gregory H.; Ban, Vladimir S.; Mykietyn, E.; Mohr, D. R.

    1992-08-01

    Popcorn noise, also called burst noise, manifests itself as a random charge fluctuation in linear In(subscript 0.53)Ga(subscript 0.47)As detector arrays. The noise is not present in all the devices; it may affect only 1 or 2% of the photodiodes at a moderately high reverse bias (5 V) but represents a potential performance limitation for the InGaAs photodetector arrays. The random charge fluctuations can be of the order of a few hundred to a million electrons at room temperature and can also be observed at temperatures as low as 200 K. Our studies suggest that dislocations which originate in the InP substrate are the major cause of popcorn noise. This noise can be significantly reduced or completely eliminated by reducing the reverse bias of the photodiodes from 5 V to 2 V or less. Crystal defects seem to cause the popcorn noise when the diode is substantially depleted. A lower reverse bias prevents the depletion width from reaching these defects and thereby prevents the possible generation of popcorn noise.

  12. Multiwavelength infrared focal plane array detector

    NASA Technical Reports Server (NTRS)

    Forrest, Stephen R. (Inventor); Olsen, Gregory H. (Inventor); Kim, Dong-Su (Inventor); Lange, Michael J. (Inventor)

    1995-01-01

    A multiwavelength focal plane array infrared detector is included on a common substrate having formed on its top face a plurality of In.sub.x Ga.sub.1-x As (x.ltoreq.0.53) absorption layers, between each pair of which a plurality of InAs.sub.y P.sub.1-y (y<1) buffer layers are formed having substantially increasing lattice parameters, respectively, relative to said substrate, for preventing lattice mismatch dislocations from propagating through successive ones of the absorption layers of decreasing bandgap relative to said substrate, whereby a plurality of detectors for detecting different wavelengths of light for a given pixel are provided by removing material above given areas of successive ones of the absorption layers, which areas are doped to form a pn junction with the surrounding unexposed portions of associated absorption layers, respectively, with metal contacts being formed on a portion of each of the exposed areas, and on the bottom of the substrate for facilitating electrical connections thereto.

  13. The Trace Analysis of DEET in Water using an On-line Preconcentration Column and Liquid Chromatography with UV Photodiode Array Detection

    EPA Science Inventory

    A method for the detection of trace levels of N,N-diethyl-m-toluamide (DEET) in water is discussed. The method utilizes an on-line preconcentration column in series with high performance liquid chromatography (HPLC) and UV photodiode array detection. DEET, a common insect repel...

  14. Filtered Silicon Photodiodes for Plasma Diagnostics

    NASA Astrophysics Data System (ADS)

    Idzorek, George; Bartlett, Roger

    1999-11-01

    Silicon photodiodes possess excellent properties for measuring low temperature plasmas. These include a nominally flat response, insensitivity to surface contamination, low voltage biasing requirements, sensitivity to low energy photons, excellent detector to detector response reproducibility, and ability to operate in poor vacuum or gas backfilled experiments. We have characterized silicon photodiodes from 1 eV to 10 keV photon energy for time response and signal saturation levels. Our 'standard' detector assembly, the XUV-7, provides seven 0.2x0.2 mm photodiodes arrayed on a 5.3 mm circle in a vacuum leak-tight, electrically isolated, low noise, high bandwidth, x-ray filtered assembly in a compact package 94 mm long by 37 mm diameter. Other custom-built assemblies provide readouts for transmission grating spectrometers, and act as tiny x-ray detectors used in confined space applications. We have used our silicon photodiodes to diagnose low-density plasmas produced on explosive pulsed power experiments with Bremsstrahlung temperatures of about 100 eV and also high-density z-pinch plasmas with Planckian temperatures up to 200 eV.

  15. Review of reliability issues of metal-semiconductor-metal and avalanche photodiode photonic detectors

    Microsoft Academic Search

    Kevin F Brennan; Joe Haralson; Joseph W Parks; Ali Salem

    1999-01-01

    In this paper, we present a brief review of the principal mechanisms that influence the reliability of metal杝emiconductor杕etal (MSM) interdigitated photodetectors and avalanche photodiodes (APD). The most important mechanism influencing reliability in these devices is the dark current. However, other mechanisms such as edge and microplasmic breakdown and electrode degradation, can also affect device reliability. In this study, we describe

  16. Ion implanted photodiode detectors in epitaxial /Ga/x/In/1-x//As

    NASA Technical Reports Server (NTRS)

    Ajmera, P. K.; Hauser, J. R.

    1975-01-01

    Ion implanted p-n junction photodiodes in epitaxially grown (Ga(x)In(1-x))As material are reported on here. Photoresponse in these diodes was investigated for approximately the entire composition range of x between zero and one. High values for quantum efficiency were obtained for the devices with a high value of x.

  17. Noise reduction methods of single photon detector based on InGaAs/InP avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Krivyakin, G. K.; Pleshkov, A. S.; Zverev, A. V.; Ryabtsev, I. I.; Kurochkin, V. L.

    2014-10-01

    This work is dedicated to the problem of noise reduction of single photon detector development based on InGaAs-InP avalanche photodiodes. Dark count probability and quantum efficiency of the detectors have been measured. We present the experimental fiber based quantum key distribution setup with phase coding of single photon states. The autocompensation two way optical scheme (plug&play) is used. The single photon source is the strongly attenuated laser pulse which goes through two paths of Mach-Zehnder interferometer where it undergoes the phase coding. Quantum channel is formed by 25 km single mode fiber. To generate the quantum key the four phases BB84 protocol is used.

  18. Capillary electrophoresis with photodiode array detection of processable poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate aqueous dispersions.

    PubMed

    Diah, Anang W M; Holdsworth, Clovia I; Holdsworth, John L; Belcher, Warwick; Quirino, Joselito P

    2012-12-01

    The application of capillary electrophoresis (CE) with on-line photodiode array detection to the analysis of processable poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate (PEDOT/PSS) aqueous dispersions is presented. The dispersions were prepared by oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT) in the presence of PSS. The separation of PEDOT/PSS complexes and PSS was achieved using sodium borate (pH 9.2) in a fused silica capillary and positive polarity. The electrophoretic behavior and UV spectra of the negatively charged complexes were correlated to the amount of PEDOT attached to PSS. The ability of CE to predict the conductivity of films produced from spin coating of PEDOT/PSS dispersions was also proposed. PMID:23092869

  19. A validated high performance liquid chromatograph-photodiode array method for simultaneous determination of 10 bioactive components in compound hongdoushan capsule

    PubMed Central

    Zhu, Liancai; Yang, Xian; Tan, Jun; Wang, Bochu; Zhang, Xue

    2014-01-01

    Background: The compound Hongdoushan capsule (CHC) is widely known as compound herbal preparation and is often used to treat ovarian cancer and breast cancer, and to enhance the body immunity, etc., in clinical practice. Objective: To determine simultaneously 10 bioactive components from CHC, namely glycyrrhetinic acid, liquiritin, glycyrrhizin, baccatin III, 10-deacetylbaccatin III, cephalomannine, taxol, ginsenoside Rg1, ginsenoside Re, and ginsenoside Rb1. Materials and Methods: A high performance liquid chromatograph method coupled with photodiode array detector was developed and validated for the 1st time. Chromatographic analysis was performed on a SHIMADZU C18 by utilizing a gradient elution program. The mobile phase was acetonitrile (A)-water (B) at a flow rate of 0.8 mL/min. Results: The calibration curve was linear over the investigated concentration ranges with the values of r2 higher than 0.9993 for all the 10 bioactive components. The average recovery rates range from 98.4% to 100.5% with relative standard deviations ?2.9%. The developed method was successfully applied to analyze 10 compounds in six CHC samples from different batches. In addition, the herbal sources of 32 chromatographic peaks were identified through comparative studying on chromatograms of standard, the respective extracts of Hongdoushan, RenShen, GanCao, and CHC. Conclusion: All the results imply that the accurate and reproducible method developed has high separation rate and enables the determination of 10 bioactive components in a single run for the quality control of CHC. PMID:24696551

  20. Coherent Detector Arrays for Continuum and Spectral Line Applications

    NASA Technical Reports Server (NTRS)

    Gaier, Todd C.

    2006-01-01

    This viewgraph presentation reviews the requirements for improved coherent detector arrays for use in continuum and spectral line applications. With detectors approaching fundamental limits, large arrays offer the only path to sensitivity improvement. Monolithic Microwave Integrated Circuit (MMIC) technology offers a straightforward path to massive focal plane millimeter wave arrays: The technology will readily support continuum imagers, polarimeters and spectral line receivers from 30-110 GHz. Science programs, particularly large field blind surveys will benefit from simultaneous observations of hundreds or thousands of pixels 1000 element array is competitive with a cost less than $2M.

  1. Stability and quantum efficiency performance of silicon photodiode detectors in the far ultraviolet.

    PubMed

    Canfield, L R; Kerner, J; Korde, R

    1989-09-15

    Recent improvements in silicon photodiode fabrication technology have resulted in the production of photodiodes which are stable after prolonged exposure to short wavelength radiation and which have efficiencies in the far ultraviolet close to those predicted using a value of 3.63 eV for electron-hole pair production in Si. Quantum efficiency and stability data are presented in the 6-124-eV region for several variations on the basic successful design and on devices with extremely thin silicon dioxide antireflecting/passivating layers. The results indicate that the oxide is dominant in determining many of the performance parameters and that a stable efficient far ultraviolet diode can be fabricated by careful control of the Si-SiO(2) interface quality. PMID:20555802

  2. Stability and quantum efficiency performance of silicon photodiode detectors in the far ultraviolet

    NASA Astrophysics Data System (ADS)

    Canfield, L. R.; Kerner, Jonathan; Korde, Raj

    1989-09-01

    Recent improvements in silicon photodiode fabrication technology have resulted in the production of photodiodes which are stable after prolonged exposure to short wavelength radiation and which have efficiencies in the far ultraviolet close to those predicted using a value of 3.63 eV for electron-hole pair production in Si. Quantum efficiency and stability data are presented in the 6-124-eV region for several variations on the basic successful design and on devices with extremely thin silicon dioxide antireflecting/passivating layers. The results indicate that the oxide is dominant in determining many of the performance parameters and that a stable efficient far ultraviolet diode can be fabricated by careful control of the Si-SiO2 interface quality.

  3. Energy resolution of scintillation detectors readout with large area avalanche photodiodes and photomultipliers

    Microsoft Academic Search

    M. Moszynski; M. Kapusta; D. Wolski; M. Szawlowski; W. Klamra

    1998-01-01

    The energy resolution of small NaI(Tl), CsI(Tl), BGO, GSO, YAP and LSO crystals has been studied using 16 mm diameter large area avalanche photodiodes (LAAPD) and a 52 mm diameter photomultiplier. The best result of 4.8% for 662 keV ?-rays from a 137Cs source was obtained with a 9 mm in diameter by 9 mm high CsI(Tl) scintillator coupled to

  4. The channeling avalanche photodiode - A novel ultra-low-noise interdigitated p-n junction detector

    Microsoft Academic Search

    F. Capasso

    1982-01-01

    A novel avalanche photodiode (APD) concept, the channeling APD, is proposed. Using a new interdigitated p-n junction structure, electrons and holes are spatially separated and impact ionize in layers of different band gap. Thus the effective ionization-rates ratio can be made extremely high (kappa = alpha\\/beta greater than 100), while maintaining a high gain, by a proper choice of the

  5. PbS-PbSe IR detector arrays

    NASA Technical Reports Server (NTRS)

    Barrett, John R. (Inventor)

    1986-01-01

    A silicon wafer is provided which does not employ individually bonded leads between the IR sensitive elements and the input stages of multiplexers. The wafer is first coated with lead selenide in a first detector array area and is thereafter coated with lead sulfide within a second detector array area. The described steps result in the direct chemical deposition of lead selenide and lead sulfide upon the silicon wafer to eliminate individual wire bonding, bumping, flip chipping, planar interconnecting methods of connecting detector array elements to silicon chip circuitry, e.g., multiplexers, to enable easy fabrication of very long arrays. The electrode structure employed, produces an increase in the electrical field gradient between the electrodes for a given volume of detector material, relative to conventional electrode configurations.

  6. Achieving a Linear Dose Rate Response in Pulse-Mode Silicon Photodiode Scintillation Detectors Over a Wide Range of Excitations

    NASA Astrophysics Data System (ADS)

    Carroll, Lewis

    2014-02-01

    We are developing a new dose calibrator for nuclear pharmacies that can measure radioactivity in a vial or syringe without handling it directly or removing it from its transport shield 損ig. The calibrator's detector comprises twin opposing scintillating crystals coupled to Si photodiodes and current-amplifying trans-resistance amplifiers. Such a scheme is inherently linear with respect to dose rate over a wide range of radiation intensities, but accuracy at low activity levels may be impaired, beyond the effects of meager photon statistics, by baseline fluctuation and drift inevitably present in high-gain, current-mode photodiode amplifiers. The work described here is motivated by our desire to enhance accuracy at low excitations while maintaining linearity at high excitations. Thus, we are also evaluating a novel 損ulse-mode analog signal processing scheme that employs a linear threshold discriminator to virtually eliminate baseline fluctuation and drift. We will show the results of a side-by-side comparison of current-mode versus pulse-mode signal processing schemes, including perturbing factors affecting linearity and accuracy at very low and very high excitations. Bench testing over a wide range of excitations is done using a Poisson random pulse generator plus an LED light source to simulate excitations up to 106 detected counts per second without the need to handle and store large amounts of radioactive material.

  7. The Indiana silicon sphere 4? charged-particle detector array

    Microsoft Academic Search

    K. Kwiatkowski; D. S Bracken; K. B Morley; J. Brzychczyk; E Renshaw Foxford; K. Komisarcik; V. E Viola; N. R Yoder; J. Dorsett; J. Poehlman; N. Madden; J. Ottarson

    1995-01-01

    A low threshold charged particle detector array for the study of fragmentation processes in light-ion-induced reactions has been constructed and successfully implemented at the IUCF and Saturne II accelerators. The array consists of 162-triple-element detector telescopes mounted in a spherical geometry and covering 74% of 4? in solid angle. Telescope elements are composed of (1) an axial-field gas ionization chamber

  8. Data acquisition for experiments with multi-detector arrays

    NASA Astrophysics Data System (ADS)

    Chatterjee, A.; Kamerkar, Sushil; Jethra, A. K.; Padmini, S.; Diwakar, M. P.; Pande, S. S.; Ghodgaonkar, M. D.

    2001-07-01

    Experiments with multi-detector arrays have special requirements and place higher demands on computer data acquisition systems. In this contribution we discuss data acquisition systems with special emphasis on multi-detector arrays and in particular we describe a new data acquisition system, AMPS which we have developed recently which is in regular use in experiments at the Pelletron Laboratory, Mumbai. This includes the in-house development of a dedicated crate controller, PC interface card and software.

  9. Comparative Performance of the Photomultiplier Tube and the Silicon Avalanche Photodiode When Used as Detectors in Angular Scattering Measurements

    NASA Astrophysics Data System (ADS)

    Kroner, D. O.; Nelson, R. M.; Boryta, M. D.; Hapke, B. W.; Manatt, K.; Smythe, W. D.

    2014-12-01

    We report the results of a comparative study of two types of photometric detectors that are commonly used for, spacecraft, ground-based telescope, and laboratory observations in support of precise angular scattering investigations of the type described in a companion paper (Nelson et al., this meeting). The performance of the state of the art Hamamatsu C12703-01 Silicon Avalanche photodiode (SAD) was compared to that of the Hamamatsu R928 Photomultiplier tube (PMT). The Hamamatsu R928 evolved from a sequence of photometric detectors with a long history of use in support of laboratory and remote sensing studies, tracing backwards to include the RCA 1P21 and the RCA 931A. Two newly acquired SADs were bench tested along with a new R928 photomultiplier tube that was thermoelectrically cooled to -10 deg C. The SAD's employed electronic thermal compensation supplied by the manufacturer. The SADs and PMT measured electromagnetic radiation from solid-state lasers of wavelength 635 nm after the radiation was reflected from diffusely-scattering surfaces of varying albedos. The SADs were housed on tripods that were co-aligned with the PMT and laser. The photometric detectors were placed 4.3 meters from a reflecting disk. The disk was rotated to reduce the effect of laser speckle. All detectors in the experiment were equipped with notch filters that transmit light only of the wavelength emitted by the laser. Three SR830 DSP Lock-in Amplifiers were connected to the detectors and various setting configurations were compared in order to optimize signal to noise. Neutral Density filters (ND 0,3 and ND 0,9) were placed in the light path to determine the linearity in the response function of the detectors. We conclude that in this application SADs and PMTs produce comparable photometric precision and fidelity. SADs offer greater convenience because thermal compensation circuitry is integrated with the detector. This work was partially supported by NASA's Cassini Science Investigation program.

  10. Revolutionary impact of today's array detector technology on chemical analysis

    NASA Astrophysics Data System (ADS)

    Radspinner, David A.; Fields, Robert E.; Earle, Colin W.; Denton, M. Bonner

    1991-12-01

    State-of-the-art array detector technology is having a profound impact on numerous types of chemical analysis. The unique capabilities of these detectors create unprecedented opportunities in the various domains of high resolution, ultra sensitive optical spectroscopy. These array detectors, including charge coupled devices (CCDs) and charge injection devices (CIDs) have found successful application in molecular fluorescence, chemiluminescence, and atomic emission spectroscopies. The potential of these detectors for spatial and spectral imaging has been realized in a variety of applications including thin layer chromatography and flow cytometry. Applications of array detectors to these areas are discussed along with the inherently unique methods of operation such as random access integration, time delay integration, and flat fielding.

  11. Charge Transport in Arrays of Semiconductor Gamma-Ray Detectors

    Microsoft Academic Search

    H. H. Barrett; J. D. Eskin; H. B. Barber

    1995-01-01

    We analyze the effects of electrode size on performance of arrays of semiconductor gamma-ray detectors, especially when there is significant charge trapping. With large electrodes, motions of holes and electrons are of equal importance, but when the positive electrode is segmented into an array of small elements the contributions of holes to the output, and hence the effects of hole

  12. The next generation of monolithic infrared detector arrays

    Microsoft Academic Search

    Abhay M. Joshi; Murzy Jhabvala; Peter Shu

    1998-01-01

    Recently NASA announced an initiative ``X-2000'' whose ultimate goal is ``satellite-on-a-chip.'' We propose advanced, Monolithic InGaAs-on-silicon Short Wave Infrared (SWIR), and Monolithic InSb-on-silicon Medium Wave Infrared (MWIR) detector arrays for X-2000. To achieve ``satellite-on-a-chip'' goal, it is imperative to have a fully integrated Focal Plane Array on one wafer substrate, preferably silicon. A (512512) High Resolution Focal Plane Array structure

  13. Turntable Wide Band Infrared Detector Array for Space Situational Awareness

    Microsoft Academic Search

    J. Andrews; S. Restaino; S. Teare; S. Krishna; C. Wilcox; T. Martinez

    2007-01-01

    The Center for High Technology Materials at the University of New Mexico has been investigating tunable quantum well\\/dot detectors for infrared detection. These devices have been manufactured in 300 x 256 pixel arrays and can be adjusted to obtain a maximum responsivity to wavelengths ranging from 1 mm to 10 mm by applying an external bias voltage. This detector has

  14. Silicon photodiode characterization from 1 eV to 10 keV

    NASA Astrophysics Data System (ADS)

    Idzorek, George C.; Bartlett, R. J.

    1997-10-01

    Silicon photodiodes offer a number of advantages over conventional photocathode type soft x-ray detectors in pulsed power experiments. These include a nominally flat response, insensitivity to surface contamination, low voltage biasing requirements, sensitivity to low energy photons, excellent detector to detector response reproducibility, and ability to operate in poor vacuum or gas backfilled experiments. Silicon photodiodes available from International Radiation Detectors (IRD), Torrance, California have been characterized for absolute photon response from 1 eV to 10 keV photon energy, time response, and signal saturation levels. We have assembled individually filtered photodiodes into an array designated the XUV-7. The XUV-7 provides seven photodiodes in a vacuum leak tight, electrically isolated, low noise, high bandwidth, x-ray filtered assembly in a compact package with a 3.7 cm outside diameter. In addition we have assembled the diodes in other custom configurations as detectors for spectrometers. Our calibration measurements show factor of ten deviations from the silicon photodiode theoretical flat response due to diode sensitivity outside the center 'sensitive area.' Detector response reproducibility between diodes appears to be better than 5%. Time response measurements show a 10 - 90% rise time of about 0.1 nanoseconds and a fall time of about 0.5 nanoseconds. Silicon photodiodes have proven to be a versatile and useful complement to our standard photocathode detectors for soft x-ray measurement and are very competitive with diamond for a number of applications.

  15. Triangular-barrier quantum rod photodiodes: Their fabrication and detector characteristics

    SciTech Connect

    Ohmori, M.; Kobayashi, Y.; Vitushinskiy, P.; Nakamura, S.; Kojima, T.; Sakaki, H. [Toyota Technological Institute, 2-12-1 Hisakata, Tempaku-ku, Nagoya 468-0034 (Japan)

    2014-02-24

    We have fabricated a GaAs-based triangular-barrier photodiode, in which self-assembled InGaAs quantum rods (Q-rods) are embedded in its barrier region. Transport study at 100?K has shown that electrons start to flow mainly through Q-rods when a bias is set above a threshold. Upon illumination, photo-generated holes are found to accumulate in the middle portion of Q-rods and efficiently lower the local barrier height, yielding the responsivity as high as 10{sup 5}?A/W at the incident light of 1 fW.

  16. 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.

  17. Vacuum photodiode detectors for broadband vacuum ultraviolet detection in the Saha Institute of Nuclear Physics Tokamak

    NASA Astrophysics Data System (ADS)

    Rao, C. V. S.; Shankara Joisa, Y.; Hansalia, C. J.; Hui, Amit K.; Paul, Ratan; Ranjan, Prabhat

    1997-02-01

    We report on the application of the vacuum photodiode to detect vacuum ultraviolet (VUV) radiation emitted from the Saha Institute of Nuclear Physics (SINP) Tokamak. It is simple to fabricate and provides broadband spectral response in the VUV and ultrasoft x ray (10 eV-1 keV). In our design, a stainless steel photocathode is used, which has a response identical to tungsten in the wavelength range 100-1200 . Its surface is passivated, to minimize contamination and monolayer deposition, by electropolishing it. Some representative experimental results illustrating the range of applicability are presented with special emphasis on its performance in disruptive shots.

  18. Investigation of depth-of-interaction by pulse shape discrimination in multicrystal detectors read out by avalanche photodiodes

    SciTech Connect

    Saoudi, A.; Pepin, C.M.; Dion, F.; Bentourkia, M.; Lecomte, R. [ Univ. de Sherbrooke, Quebec (Canada). Dept. of Nuclear Medicine and Radiobiology] [Univ. de Sherbrooke, Quebec (Canada). Dept. of Nuclear Medicine and Radiobiology; Andreaco, M.; Casey, M.; Nutt, R. [CTI PET Systems Inc., Knoxville, TN (United States)] [CTI PET Systems Inc., Knoxville, TN (United States); Dautet, H. [EG and G Optoelectronics, Vaudreuil, Quebec (Canada)] [EG and G Optoelectronics, Vaudreuil, Quebec (Canada)

    1999-06-01

    The measurement of depth of interaction (DOI) within detectors is necessary to improve resolution uniformity across the FOV of small diameter PET scanners. DOI encoding by pulse shape discrimination (PSD) has definite advantages as it requires only one readout per pixel and it allows DOI measurement of photoelectric and Compton events. The PSD time characteristics of various scintillators were studied with avalanche photodiodes (APD) and the identification capability was tested in multi-crystal assemblies with up to four scintillators. In the PSD time spectrum of an APD-GSO/LSO/BGO/CsI(Tl) assembly, four distinct time peaks at 45, 26, 88 and 150 ns relative to a fast test pulse, having resolution of 10.6, 5.2, 20 and 27 ns, can be easily separated. Whereas the number and position of scintillators in the multi-crystal assemblies affect detector performance, the ability to identify crystals is not compromised. Compton events have a significant effect on PSD accuracy, suggesting that photopeak energy gating should be used for better crystal identification. However, more sophisticated PSD techniques using parametric time-energy histograms can also improve crystal identification in cases where PSD time or energy discrimination alone is inadequate. These results confirm the feasibility of PSD DOI encoding with APD-based detectors for PET.

  19. Comparison of magnetic resonance imaging-compatible optical detectors for in-magnet tissue spectroscopy: photodiodes versus silicon photomultipliers

    NASA Astrophysics Data System (ADS)

    El-Ghussein, Fadi; Jiang, Shudong; Pogue, Brian W.; Paulsen, Keith D.

    2014-07-01

    Tissue spectroscopy inside the magnetic resonance imaging (MRI) system adds a significant value by measuring fast vascular hemoglobin responses or completing spectroscopic identification of diagnostically relevant molecules. Advances in this type of spectroscopy instrumentation have largely focused on fiber coupling into and out of the MRI; however, nonmagnetic detectors can now be placed inside the scanner with signal amplification performed remotely to the high field environment for optimized light detection. In this study, the two possible detector options, such as silicon photodiodes (PD) and silicon photomultipliers (SiPM), were systematically examined for dynamic range and wavelength performance. Results show that PDs offer 10 (160 dB) dynamic range with sensitivity down to 1 pW, whereas SiPMs have 10 (140 dB) dynamic range and sensitivity down to 10 pW. A second major difference is the spectral sensitivity of the two detectors. Here, wavelengths in the 940 nm range are efficiently captured by PDs (but not SiPMs), likely making them the superior choice for broadband spectroscopy guided by MRI.

  20. Comparison of magnetic resonance imaging-compatible optical detectors for in-magnet tissue spectroscopy: photodiodes versus silicon photomultipliers

    PubMed Central

    El-Ghussein, Fadi; Jiang, Shudong; Pogue, Brian W.; Paulsen, Keith D.

    2014-01-01

    Abstract. Tissue spectroscopy inside the magnetic resonance imaging (MRI) system adds a significant value by measuring fast vascular hemoglobin responses or completing spectroscopic identification of diagnostically relevant molecules. Advances in this type of spectroscopy instrumentation have largely focused on fiber coupling into and out of the MRI; however, nonmagnetic detectors can now be placed inside the scanner with signal amplification performed remotely to the high field environment for optimized light detection. In this study, the two possible detector options, such as silicon photodiodes (PD) and silicon photomultipliers (SiPM), were systematically examined for dynamic range and wavelength performance. Results show that PDs offer 108 (160燿B) dynamic range with sensitivity down to 1 pW, whereas SiPMs have 107 (140燿B) dynamic range and sensitivity down to 10爌W. A second major difference is the spectral sensitivity of the two detectors. Here, wavelengths in the 940爊m range are efficiently captured by PDs (but not SiPMs), likely making them the superior choice for broadband spectroscopy guided by MRI. PMID:25006986

  1. Enhanced photoresponse of conformal TiO{sub 2}/Ag nanorod array-based Schottky photodiodes fabricated via successive glancing angle and atomic layer deposition

    SciTech Connect

    Haider, Ali; Biyikli, Necmi, E-mail: biyikli@unam.bilkent.edu.tr [National Nanotechnology Research Center (UNAM), Bilkent University, Bilkent, Ankara 06800, Turkey and Institute of Materials Science and Nanotechnology, Bilkent University, Bilkent, Ankara 06800 (Turkey); Cansizoglu, Hilal; Cansizoglu, Mehmet Fatih; Karabacak, Tansel [Department of Physics and Astronomy, University of Arkansas at Little Rock, Little Rock, Arkansas 72204 (United States); Okyay, Ali Kemal [National Nanotechnology Research Center (UNAM), Bilkent University, Bilkent, Ankara 06800 (Turkey); Institute of Materials Science and Nanotechnology, Bilkent University, Bilkent, Ankara 06800 (Turkey); Department of Electrical and Electronics Engineering, Bilkent University, Bilkent, Ankara 06800 (Turkey)

    2015-01-01

    In this study, the authors demonstrate a proof of concept nanostructured photodiode fabrication method via successive glancing angle deposition (GLAD) and atomic layer deposition (ALD). The fabricated metal-semiconductor nanorod (NR) arrays offer enhanced photoresponse compared to conventional planar thin-film counterparts. Silver (Ag) metallic NR arrays were deposited on Ag-film/Si templates by utilizing GLAD. Subsequently, titanium dioxide (TiO{sub 2}) was deposited conformally on Ag NRs via ALD. Scanning electron microscopy studies confirmed the successful formation of vertically aligned Ag NRs deposited via GLAD and conformal deposition of TiO{sub 2} on Ag NRs via ALD. Following the growth of TiO{sub 2} on Ag NRs, aluminum metallic top contacts were formed to complete the fabrication of NR-based Schottky photodiodes. Nanostructured devices exhibited a photo response enhancement factor of 1.49??10{sup 2} under a reverse bias of 3 V.

  2. Determination of eleutheroside E and eleutheroside B in rat plasma and tissue by high-performance liquid chromatography using solid-phase extraction and photodiode array detection

    Microsoft Academic Search

    Shi lan Feng; Fang di Hu; Jian xiong Zhao; Xi Liu

    2006-01-01

    A HPLC method with photodiode array detection (PDA) was developed for the determination and a pharmacokinetic study of eleutheroside E (ELU E) and eleutheroside B (ELU B) in rat plasma and tissue following an eleutherococcus injection. The analysis was performed on a Kromasil C18 column, using water-acetonitrile as the gradient mobile phase and 0.8mL\\/min flow rate. Detection wavelengths of ELU

  3. Automated on-line liquid chromatographyphotodiode array杕ass spectrometry method with dilution line for the determination of bisphenol A and 4-octylphenol in serum

    Microsoft Academic Search

    Min Liu; Yuki Hashi; Fengyun Pan; Jianguo Yao; Guanqun Song; Jin-Ming Lin

    2006-01-01

    A novel on-line liquid chromatographyphotodiode array detection杕ass spectrometry (LC朌AD朚S) system was established with restricted-access media (RAM) pre-column and dilution line combined with a column-switching valve. The serum samples were injected directly onto pre-column under diluted condition by dilution line. After elution of proteins in the serum, the analytes were backflushed onto an ODS analytical column using a six-port column-switching device.

  4. Optimisation on the two-layer stack gamma detectors of CsI(Tl) coupled with a pin photodiode for non-destructive testing.

    PubMed

    Bai, Jin Hyoung; Whang, Joo Ho

    2011-07-01

    This paper proposed the two-layer stack scintillator-coupled photodiode detector to improve the measurement accuracy of the gamma-ray scanning. Both MCNPX and DETECT97 code were used to design the detector. The two manufactured two-layer stack gamma detectors were used to measure the density profile of the distillation column of the radiographic non-intrusive process diagnostic area. To compare the measurement accuracy of the density profile through the non-destructive transmission test, the relative error of the four fluids used for the process diagnostics was analysed. To summarise the measurement results with regard to the relative error of the NaI(Tl) detector and the manufactured detector by material as well as the total relative error, the total relative error of the NaI(Tl) detector was about 15.7 %, whereas that of the two-layer stack CsI(Tl) with photodiode detectors were about 5 %. This paper confirmed that the measurement accuracy of the detector proposed was improved by about three times as compared with the NaI(Tl) detector mostly used for non-destructive testing. PMID:21561939

  5. Design of a large-area CsI(Tl) photo-diode array for explosives detection by neutron-activation gamma-ray spectroscopy

    Microsoft Academic Search

    R. J Evans; I. D Jupp; F Lei; D Ramsden

    1999-01-01

    A design for a large area, position-sensitive gamma-ray spectrometer for use in imaging explosive materials is described. The design has been optimised for use in the energy range from 2 to 12MeV. At 5MeV, the spectral resolution of each CsI(Tl)-photodiode pixel is better than 3% FWHM. The multi-element detector system, when used in conjunction with a coded-aperture mask, is able

  6. Adaptive Waveform Correlation Detectors for Arrays: Algorithms for Autonomous Calibration

    SciTech Connect

    Ringdal, F; Harris, D B; Dodge, D; Gibbons, S J

    2009-07-23

    Waveform correlation detectors compare a signal template with successive windows of a continuous data stream and report a detection when the correlation coefficient, or some comparable detection statistic, exceeds a specified threshold. Since correlation detectors exploit the fine structure of the full waveform, they are exquisitely sensitive when compared to power (STA/LTA) detectors. The drawback of correlation detectors is that they require complete knowledge of the signal to be detected, which limits such methods to instances of seismicity in which a very similar signal has already been observed by every station used. Such instances include earthquake swarms, aftershock sequences, repeating industrial seismicity, and many other forms of controlled explosions. The reduction in the detection threshold is even greater when the techniques are applied to arrays since stacking can be performed on the individual channel correlation traces to achieve significant array gain. In previous years we have characterized the decrease in detection threshold afforded by correlation detection across an array or network when observations of a previous event provide an adequate template for signals from subsequent events located near the calibration event. Last year we examined two related issues: (1) the size of the source region calibration footprint afforded by a master event, and (2) the use of temporally incoherent detectors designed to detect the gross envelope structure of the signal to extend the footprint. In Case 1, results from the PETROBAR-1 marine refraction profile indicated that array correlation gain was usable at inter-source separations out to one or two wavelengths. In Case 2, we found that incoherent detectors developed from a magnitude 6 event near Svalbard were successful at detecting aftershocks where correlation detectors derived from individual aftershocks were not. Incoherent detectors might provide 'seed' events for correlation detectors that then could extend detection to lower magnitudes. This year we addressed a problem long known to limit the acceptance of correlation detectors in practice: the labor intensive development of templates. For example, existing design methods cannot keep pace with rapidly unfolding aftershock sequences. We successfully built and tested an object-oriented framework (as described in our 2005 proposal) for autonomous calibration of waveform correlation detectors for an array. The framework contains a dynamic list of detectors of several types operating on a continuous array data stream. The list has permanent detectors: beam forming power (STA/LTA) detectors which serve the purpose of detecting signals not yet characterized with a waveform template. The framework also contains an arbitrary number of subspace detectors which are launched automatically using the waveforms from validated power detections as templates. The implementation is very efficient such that the computational cost of adding subspace detectors was low. The framework contains a supervisor that oversees the validation of power detections, and periodically halts the processing to revise the portfolio of detectors. The process of revision consists of collecting the waveforms from all detections, performing cross-correlations pairwise among all waveforms, clustering the detections using correlations as a distance measure, then creating a new subspace detector from each cluster. The collection of new subspace detectors replaces the existing portfolio and processing of the data stream resumes. This elaborate scheme was implemented to prevent proliferation of closely-related subspace detectors. The method performed very well on several simple sequences: 2005 'drumbeat' events observed locally at Mt. St. Helens, and the 2003 Orinda, CA aftershock sequence. Our principal test entailed detection of the aftershocks of the San Simeon earthquake using the NVAR array; in this case, the system automatically detected and categorized approximately 2/3 of the events above magnitude 2.8.

  7. [Structure identification of reactive dyes by high performance liquid chromatography-photodiode array detection/mass spectrometry].

    PubMed

    Fu, Xinmei; Zhang, Rong; Wu, Zuwang

    2014-11-01

    Based on years of experience on analyzing reactive dyes by high performance liquid chromatography-photodiode array detection/mass spectrometry (HPLC-DAD/MS), the essential applications for current structure identification of the commercial reactive dyes are summa- rized in three aspects. Commercial dyes always include several kinds of components. They are assistants for increasing solubility of synthetic dyes, multi-color synthetic dyes and their by-products derived from synthesis and storage. HPLC-DAD/MS technique can separate most of the components, and provide UV-Vis spectra and mass spectra individually. The separation and analysis can be achieved only through one injection without pre-purification of commercial dyes. Compared with traditional analytical methods, HPLC-DAD/MS technique reduces greatly not only the workload of analysis but also provides fully the actual compositions of the dyestuff. The reactive groups can react with ethanolamine or diethanolamine under moderate condition without structure destruction of dyes. The molecular masses before and after derivatization can be determined by MS, and then the type and number of reactive groups can be ascertained by so called "mass difference by derivative method". The chromophore of the dye can be identified by full spectrum scanning function of DAD. HPLC-DAD/MS analytical technique is very special and useful for the structure analysis of multi-component mixed commercial dyes. As examples, the identifications of three multi-component mixed structures of commercial dyes (Reactive Gray, Reactive Supra Black and Reactive Marine Blue) were given. PMID:25764650

  8. Determination of psychotropic phenylalkylamine derivatives in biological matrices by high-performance liquid chromatography with photodiode-array detection.

    PubMed

    Helmlin, H J; Brenneisen, R

    1992-02-28

    Several procedures using high-performance liquid chromatography with photodiode-array detection have been developed to create phytochemical and toxicological profiles of phenylalkylamine derivatives in biological samples (e.g. plant materials and urine). Mescaline-containing cactus samples were extracted with basic methanol, using methoxamine as internal standard; the extraction and clean-up of urine samples were performed on cation-exchange solid-phase extraction columns. The extracts were separated on a 3-micron ODS column with acetonitrile-water-phosphoric acid-hexylamine as the mobile phase. Peak detection was performed at 198 or 205 nm; peak identity and homogeneity were ascertained by on-line scanning of the UV spectra from 190 to 300 nm. The detection limit of phenylalkylamine derivatives in urine and cactus material was 0.026-0.056 micrograms/ml and 0.04 micrograms/mg, respectively. Following a single oral dose of 1.7 mg/kg methylenedioxymethylamphetamine (MDMA) the concentrations found in urine ranged from 1.48 to 5.05 micrograms/ml MDMA and 0.07-0.90 micrograms/ml methylenedioxyamphetamine (a metabolite of MDMA). The mescaline content of the cactus Trichocereus pachanoi varied between 1.09 and 23.75 micrograms/mg. PMID:1639916

  9. Optimization of a liquid chromatography method based on simultaneous electrospray ionization mass spectrometric and ultraviolet photodiode array detection for analysis of flavonoid glycosides.

    PubMed

    Cuyckens, Filip; Claeys, Magda

    2002-01-01

    Different reversed-phase liquid chromatography (LC) columns of conventional dimensions were coupled to an ultraviolet photodiode array detector (UV-DAD) and a magnetic sector-type spectrometer, equipped with an electrospray ionization (ESI) source, by a laboratory-made flow splitter. A mixture of three flavonoid-O-glycosides was employed to examine the effects of the solvent composition, the flow rate, the stationary phase, the pH and the organic acid added, on the chromatographic separation, the UV-DAD detection, the ESI process and the entire LC system with ESI-MS and UV-DAD detection. In the positive ion mode, methanol containing 1% acetic acid was by far the most sensitive in ESI-MS analysis, whereas an acetonitrile/water mobile phase containing 0.5% formic acid was proved to give the best sensitivity in LC/ESI-MS/UV-DAD analysis. In the negative ion mode, the highest sensitivity was obtained with a mobile phase containing 0.1% formic acid, while addition of bases decreased the sensititvity. The optimal flow rate was higher in negative ESI (20-50 micro L/min) than in positive ESI (5 micro L/min), and the percentage of organic phase had an influence on the sensitivity of ESI-MS detection. With regard to the selection of a suitable C(18) reversed-phase LC column, a column which is well end-capped is to be preferred, because residual silanol groups appear to impair the separation of flavonoid glycosides. The optimized LC/ESI-MS/UV-DAD method was applied to a commercial Crataegus extract, which is used in phytomedicine to treat cardiovascular problems and is known to be rich in flavonoids. It is demonstrated how UV spectra and first-order ESI mass spectra allow a fast characterization of flavonoids, even if reference compounds are not available or at hand. PMID:12478580

  10. Hybrid photomultiplier tube and photodiode parallel detection array for wideband optical spectroscopy of the breast guided by magnetic resonance imaging.

    PubMed

    El-Ghussein, Fadi; Mastanduno, Michael A; Jiang, Shudong; Pogue, Brian W; Paulsen, Keith D

    2014-01-01

    A new optical parallel detection system of hybrid frequency and continuous-wave domains was developed to improve the data quality and accuracy in recovery of all breast optical properties. This new system was deployed in a previously existing system for magnetic resonance imaging (MRI)-guided spectroscopy, and allows incorporation of additional near-infrared wavelengths beyond 850 nm, with interlaced channels of photomultiplier tubes (PMTs) and silicon photodiodes (PDs). The acquisition time for obtaining frequency-domain data at six wavelengths (660, 735, 785, 808, 826, and 849 nm) and continuous-wave data at three wavelengths (903, 912, and 948 nm) is 12 min. The dynamic ranges of the detected signal are 105 and 106 for PMT and PD detectors, respectively. Compared to the previous detection system, the SNR ratio of frequency-domain detection was improved by nearly 103 through the addition of an RF amplifier and the utilization of programmable gain. The current system is being utilized in a clinical trial imaging suspected breast cancer tumors as detected by contrast MRI scans. PMID:23979460

  11. HgCdTe infrared detectors and focal plane arrays

    Microsoft Academic Search

    J. Bajaj

    1998-01-01

    Recent advances in the areas of Mercury Cadmium Telluride (HgCdTe) material growth, detector array fabrication and Read Out Integrated Circuit (ROIC) design and fabrication have led to the demonstration of high resolution, low noise and large format reliable hybrid Infrared Focal Plane Arrays (IRFPAs). MBE HgCdTe based p-on-n planar heterostructure device fabrication has emerged as a viable technology for manufacturing

  12. High-energy interactions in kinetic inductance detectors arrays

    NASA Astrophysics Data System (ADS)

    D'Addabbo, A.; Calvo, M.; Goupy, J.; Benoit, A.; Bourrion, O.; Catalano, A.; Macias-Perez, J. F.; Monfardini, A.

    2014-07-01

    The impacts of Cosmic Rays on the detectors are a key problem for space-based missions. We are studying the effects of such interactions on arrays of Kinetic Inductance Detectors (KID), in order to adapt this technology for use on board of satellites. Before proposing a new technology such as the Kinetic Inductance Detectors for a space-based mission, the problem of the Cosmic Rays that hit the detectors during in-flight operation has to be studied in detail. We present here several tests carried out with KID exposed to radioactive sources, which we use to reproduce the physical interactions induced by primary Cosmic Rays, and we report the results obtained adopting different solutions in terms of substrate materials and array geometries. We conclude by outlining the main guidelines to follow for fabricating KID for spacebased applications.

  13. Curved focal plane detector array for wide field cameras.

    PubMed

    Dumas, Delphine; Fendler, Manuel; Baier, Nicolas; Primot, J閞鬽e; le Coarer, Etienne

    2012-08-01

    Miniaturization is the main goal for system design in future cameras. This paper offers a novel method to scale down the optical system and to improve the image quality. As with the human retina, the detector array is spherically bent to fit the curved image surface; so the field curvature aberration is directly suppressed, leading to a better resolution and a simplified optical design. By thinning the substrate, the device is monolithically curved without modifying the fabrication process of the active pixels. Optical characterizations have been performed on planar and curved focal plane based cameras to illustrate the optical advantages of detector array curvature. PMID:22859030

  14. 128 128 long-wavelength/mid-wavelength two-color HgCdTe infrared focal plane array detector with ultralow spectral cross talk.

    PubMed

    Hu, Weida; Ye, Zhenhua; Liao, Lei; Chen, Honglei; Chen, Lu; Ding, Ruijun; He, Li; Chen, Xiaoshuang; Lu, Wei

    2014-09-01

    High temporal and spatial coherent simultaneous long-wavelength/mid-wavelength (LW/MW) two-color focal plane array (FPA) infrared detection is the cutting-edge technique for third-generation infrared remote sensing. In this Letter, HgCdTe LW/MW two-color infrared detectors were designed and fabricated. The top long-wavelength and bottom mid-wavelength infrared planar photodiodes were processed by selective B(+)-implantation after etching the long-wavelength epilayer into a curvature and exposing the mid-wavelength layers for the implantation of the n region of the MW photodiode by a micro-mesa array technique. A 128128??MW/LW HgCdTe infrared FPA detector is fabricated photo-lithographically by simultaneous nonplanar B(+)-implantation of the LW and MW photodiodes, passivation and metallization of the sidewalls, mesa isolation, and flip-chip hybridization with a read-out integrated circuit. The inner mechanisms for suppressing the cross talk and improving photoresponse have been carried out by combining experimental work with numerical simulations. PMID:25166105

  15. SRAM As An Array Of Energetic-Ion Detectors

    NASA Technical Reports Server (NTRS)

    Buehler, Martin G.; Blaes, Brent R.; Lieneweg, Udo; Nixon, Robert H.

    1993-01-01

    Static random-access memory (SRAM) designed for use as array of energetic-ion detectors. Exploits well-known tendency of incident energetic ions to cause bit flips in cells of electronic memories. Design of ion-detector SRAM involves modifications of standard SRAM design to increase sensitivity to ions. Device fabricated by use of conventional complementary metal oxide/semiconductor (CMOS) processes. Potential uses include gas densimetry, position sensing, and measurement of cosmic-ray spectrum.

  16. Integrated uncooled infrared detector imaging arrays

    Microsoft Academic Search

    R. A. Wood; C. J. Han; P. W. Kruse

    1992-01-01

    The authors describe a new type of infrared (IR) focal plane consisting of a 2-D array of microminiature bolometers (microbolometers) fabricated, complete with readout electronics, as a monolithic silicon chip. These focal planes require no cooling for sensitive detection of IR radiation. The authors report high-quality IR imaging obtained with such focal planes

  17. Empirical approach to the description of spectral performance degradation of silicon photodiodes used as particle detectors

    NASA Astrophysics Data System (ADS)

    Kalinka, G.; Nov醟, M.; Simon, A.; Pastuovi?, .; Jak歩?, M.; Kiss, . Z.

    2009-06-01

    The spectral deterioration of Hamamatsu S5821 silicon photodiodes for ion types and energies frequently used in Ion Beam Analysis was investigated. Focused proton beams with energies 430 keV and 2 MeV were applied to generate radiation damage via an area selective ion implantation in unbiased diodes at room temperature. The variations of spectroscopic features were measured "in situ" by Ion Beam Induced Current (IBIC) method as a function of fluence, within the 10 9-5 10 12 ion/cm 2 range and diode bias voltages, between 0 and 100 V. An empirical model has been developed to describe the radiation damage. Equations are derived for the variations of the normalized peak position and peak width. The derived empirical equations are physically correct, as far as they account for the superposition of the influence of charge carrier trapping by native and radiation-induced defects and for the effect of charge carrier velocity saturation with electric field strength, as well.

  18. The channeling avalanche photodiode - A novel ultra-low-noise interdigitated p-n junction detector

    NASA Astrophysics Data System (ADS)

    Capasso, F.

    1982-09-01

    A novel avalanche photodiode (APD) concept, the channeling APD, is proposed. Using a new interdigitated p-n junction structure, electrons and holes are spatially separated and impact ionize in layers of different band gap. Thus the effective ionization-rates ratio can be made extremely high (kappa = alpha/beta greater than 100), while maintaining a high gain, by a proper choice of the band gap difference. In the limit of large kappa, this device mimics a channeltron photomultiplier. This structure can be fabricated using most III-V lattice matched heterojunctions, including long-wavelength materials for fiber-optical communications (1.3-1.6 micron). The design of three channeling APD's using Al(0.45)Ga(0.55)As/GaAs, InP/In(0.53)Ga(0.47)As, and AlAs(0.92)/GaSb heterojunctions is discussed in detail. Other important features of this structure are the unique capacitance-voltage characteristic, which may be important in varactor diode applications, and the interdigitized geometry which allows the depletion of large volumes of semiconductor materials doped to levels as high as 10 to the 17th/cu cm.

  19. High responsivity and wide bandwidth operation of InP-based pin-photodiode array monolithically integrated with 90 hybrid using butt-joint regrowth

    NASA Astrophysics Data System (ADS)

    Yagi, Hideki; Inoue, Naoko; Masuyama, Ryuji; Katsuyama, Tomokazu; Kikuchi, Takehiko; Onishi, Yutaka; Yoneda, Yoshihiro; Shoji, Hajime

    2014-02-01

    The InP-based pin-photodiode array monolithically integrated with a 90 hybrid consisting of multimode interference structures was fabricated using the butt-joint regrowth for compact 100 Gbps coherent receivers. The low dark current of less than 0.2 nA was obtained with InP passivation effect through the selective regrowth process in four-channel photodiodes. A responsivity including total loss of 8.3 dB in the waveguide was as high as 0.14 A/W. The wide 3 dB bandwidth of 24 GHz at a low reverse bias voltage of 1.6 V was also achieved under high optical input power conditions (photocurrent: 4 mA).

  20. 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.

  1. An Event Reconstruction Method for the Telescope Array Fluorescence Detectors

    SciTech Connect

    Fujii, T.; Ogio, S.; Yamazaki, K. [Graduate Schiool of Science, Osaka City University, Sumiyoshi, Osaka 558-8585 (Japan); Fukushima, M.; Ikeda, D.; Sagawa, H.; Takahashi, Y.; Tameda, Y. [Institute of Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Hayashi, K.; Ishimori, R.; Kobayashi, Y.; Tokuno, H.; Tsunesada, Y. [Graduate School of Science and Engineering, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 (Japan); Honda, K.; Tomida, T. [Graduate School of Medicine and Engineering, University of Yamanashi, Kofu, Yamanashi 400-8511 (Japan); Udo, S. [Faculty of Engineering, Kanagawa University, Yokohama, Kanagawa 221-8686 (Japan)

    2011-09-22

    We measure arrival directions, energies and mass composition of ultra-high energy cosmic rays with air fluorescence detector telescopes. The longitudinal profile of the cosmic ray induced extensive air shower cascade is imaged on focal plane of the telescope camera. Here, we show an event reconstruction method to obtain the primary information from data collected by the Telescope Array Fluorescence Detectors. In particular, we report on an ''Inverse Monte Carlo (IMC)'' method in which the reconstruction process searches for an optimum solution via repeated Monte Carlo simulations including characteristics of all detectors, atmospheric conditions, photon emission and scattering processes.

  2. Influence of temperature and bias voltage on the performance of a high resolution PET detector built with position sensitive avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Vandenbroucke, A.; McLaughlin, T. J.; Levin, C. S.

    2012-08-01

    We evaluate the performance of an 8 8 array of 0.9 0.9 1 mm3 cerium doped lutetium oxyothosilicate (LSO) crystals coupled to a position sensitive avalanche photodiode (PSAPD) as a function of bias voltage and temperature. We use this detector to develop a general methodology to optimize bias voltage, temperature, and gain for PET detectors using semiconductor photodetectors. This detector module will be used in a novel high resolution positron emission tomography (PET) camera dedicated to breast imaging under construction in our lab. Due to the tight packing of many PSAPDs in the system a thermal gradient is expected across the imaging heads. Data were collected for 11 PSAPD temperatures between 5癈 and 40癈 using a thermo-electric (Peltier) device. At each temperature the bias voltage was varied in steps of 5 V over a 50 V range. We present three methods to predict the optimal bias voltage at every temperature: one based on optimizing the coincidence time resolution, the others based on the relative change in PSAPD gain and leakage current due to the onset of hole multiplication. Optimal gain could also be predicted based on the quality of the flood histogram. At optimal bias voltage, the energy resolution degrades as (10.50.1)+((0.0380.006)/ 癈稵)%. Time resolution stays constant at 2.370.02 ns below 15癈. Above this temperature, time resolution deteriorates as (1.670.06)+((0.0420.002)/癈稵)ns. Even at high temperatures, all 64 crystal position peaks in the flood histogram are still clearly visible. The width of the peaks in the flood histogram show a quadratic degradation with temperature: (2.60.1)10-2+(1.60.2)10-5/(癈)2稵2. We conclude that both the quality of the flood histogram as well as the coincidence time resolution are better parameters to estimate the optimal bias voltage, than energy resolution. Optimal bias voltage is found to be dependent on the value of k, the ratio between hole and electron multiplication. We achieve optimal bias at a similar gain at all temperatures. The optimal bias voltage changes linearly across the observed range.

  3. First Results from the Telescope Array RAdar (TARA) Detector

    NASA Astrophysics Data System (ADS)

    Myers, Isaac

    2014-03-01

    The TARA cosmic ray detector has been in operation for about a year and a half. This bi-static radar detector was designed with the goal of detecting cosmic rays in coincidence with Telescope Array (TA). A new high power (25 kW, 5 MW effective radiated power) transmitter and antenna array and 250 MHz fPGA-based DAQ have been operational since August 2013. The eight-Yagi antenna array broadcasts a 54.1 MHz tone across the TA surface detector array toward our receiver station 50 km away at the Long Ridge fluorescence detector. Receiving antennas feed an intelligent DAQ that self-adjusts to the fluctuating radio background and which employs a bank of matched filters that search in real-time for chirp radar echoes. Millions of triggers have been collected in this mode. A second mode is a forced trigger scheme that uses the trigger status of the fluorescence telescope. Of those triggers collected in FD-triggered mode, about 800 correspond with well-reconstructed TA events. I will describe recent advancements in calibrating key components in the transmitter and receiver RF chains and the analysis of FD-triggered data. Work supported by W.M. Keck Foundation and NSF.

  4. A Broadband Superconducting Detector Suitable for Use in Large Arrays

    NASA Technical Reports Server (NTRS)

    Day, Peter K.; LeDuc, Henry G.; Mazin, Benjamin A.; Vayonakis, Anastasios; Zmuldzinas, Jonas

    2003-01-01

    Cryogenic detectors are extremely sensitive and have a wide variety of applications (particularly in astronomy), but are difficult to integrate into large arrays like a modern CCD (charge-coupled device) camera. As current detectors of the cosmic microwave background (CMB) already have sensitivities comparable to the noise arising from the random arrival of CMB photons, the further gains in sensitivity needed to probe the very early Universe will have to arise from large arrays. A similar situation is encountered at other wavelengths. Single-pixel X-ray detectors now have a resolving power of (Delta)E < 5 eV for single 6-keV photons, and future X-ray astronomy missions anticipate the need for 1,000-pixel arrays. Here we report the demonstration of a superconducting detector that is easily fabricated and can readily be incorporated into such an array. Its sensitivity is already within an order of magnitude of that needed for CMB observations, and its energy resolution is similarly close to the targets required for future X-ray astronomy missions.

  5. A diffuse reflectance spectral imaging system for tumor margin assessment using custom annular photodiode arrays

    PubMed Central

    Dhar, Sulochana; Lo, Justin Y.; Palmer, Gregory M.; Brooke, Martin A.; Nichols, Brandon S.; Yu, Bing; Ramanujam, Nirmala; Jokerst, Nan M.

    2012-01-01

    Diffuse reflectance spectroscopy (DRS) is a well-established method to quantitatively distinguish between benign and cancerous tissue for tumor margin assessment. Current multipixel DRS margin assessment tools are bulky fiber-based probes that have limited scalability. Reported herein is a new approach to multipixel DRS probe design, which utilizes direct detection of the DRS signal by using optimized custom photodetectors in direct contact with the tissue. This first fiberless DRS imaging system for tumor margin assessment consists of a 4 4 array of annular silicon photodetectors and a constrained free-space light delivery tube optimized to deliver light across a 256 mm2 imaging area. This system has 4.5 mm spatial resolution. The signal-to-noise ratio measured for normal and malignant breast tissue-mimicking phantoms was 35 dB to 45 dB for ? = 470 nm to 600 nm. PMID:23243571

  6. Beam profile monitor for the NSLS VUV ring employing linear photodiode arrays

    NASA Astrophysics Data System (ADS)

    Nawrocky, R. J.; Galayda, J.; Yu, L. H.; Shu, D. M.

    Among the most important parameters of a storage accelerator are the position and size of the particle beam. In an electron machine, these parameters can be derived from measurements of the emitted synchroton radiation. A system which monitors the two-dimensional profile of the synchrotron light in the NSLS VUV ring commercially available high-resolution linear photosensitive diode arrays is discussed. The optical system was designed to match the size of the image space to the dimensions of the diode sensor area. The scanning rate is automatically adjusted to hold the peaks of the profiles constant over a wide range of beam intensity variations. Video signals from the diode sensors can be readily interfaced to a computer for beam diagnostic purposes. Optics and factors determining the overall resolution of the system are discussed. Preliminary results of beam observations are presented.

  7. A diffuse reflectance spectral imaging system for tumor margin assessment using custom annular photodiode arrays.

    PubMed

    Dhar, Sulochana; Lo, Justin Y; Palmer, Gregory M; Brooke, Martin A; Nichols, Brandon S; Yu, Bing; Ramanujam, Nirmala; Jokerst, Nan M

    2012-12-01

    Diffuse reflectance spectroscopy (DRS) is a well-established method to quantitatively distinguish between benign and cancerous tissue for tumor margin assessment. Current multipixel DRS margin assessment tools are bulky fiber-based probes that have limited scalability. Reported herein is a new approach to multipixel DRS probe design, which utilizes direct detection of the DRS signal by using optimized custom photodetectors in direct contact with the tissue. This first fiberless DRS imaging system for tumor margin assessment consists of a 4 4 array of annular silicon photodetectors and a constrained free-space light delivery tube optimized to deliver light across a 256 mm(2) imaging area. This system has 4.5 mm spatial resolution. The signal-to-noise ratio measured for normal and malignant breast tissue-mimicking phantoms was 35 dB to 45 dB for ? = 470 nm to 600 nm. PMID:23243571

  8. Quantification of patulin in fruit leathers by ultra-high-performance liquid chromatography-photodiode array (UPLC-PDA).

    PubMed

    Maragos, Chris M; Busman, Mark; Ma, Liang; Bobell, John

    2015-07-01

    Patulin is a mycotoxin commonly found in certain fruit and fruit products. For this reason many countries have established regulatory limits pertaining to, in particular, apple juice and apple products. Fruit leathers are produced by dehydrating fruit puree, leaving a sweet product that has a leathery texture. A recent report in the literature described the detection of patulin at substantial levels in fruit leathers. To investigate this further, an ultra-high-performance liquid chromatography-photodiode array (UPLC-PDA) method was developed for the sensitive detection of patulin in fruit leathers. Investigations were also made of the suitability of direct analysis in real time-mass spectrometry (DART-MS) for detection of patulin from the surface of fruit leathers. Results indicated DART-MS was insufficiently sensitive for quantification from the surface of home-style apple leathers, although patulin spiked onto the surface of leather or peel could be detected. The UPLC-PDA method was used to determine the fate of patulin during the preparation of home-made fruit leathers. Interestingly, when a home-style process was used, the patulin was not destroyed, but rather increased in concentration as the puree was dehydrated. The UPLC-PDA method was also used to screen for patulin in commercial fruit leathers. Of the 36 products tested, 14 were above the limit of detection (3.5?g爇g(-1)) and nine were above the limit of quantification (12?g爇g(-1)). Positive samples were confirmed by UPLC-MS/MS. Only one sample was found above the US regulatory limit for single-strength apple juice products (50?g爇g(-1)). These results suggest patulin can be concentrated during preparation and can be found in fruit leathers. The limited survey suggests that patulin is fairly prevalent in such commercial products, but that the levels are usually low. PMID:25832782

  9. A readout for large arrays of microwave kinetic inductance detectors.

    PubMed

    McHugh, Sean; Mazin, Benjamin A; Serfass, Bruno; Meeker, Seth; O'Brien, Kieran; Duan, Ran; Raffanti, Rick; Werthimer, Dan

    2012-04-01

    Microwave kinetic inductance detectors (MKIDs) are superconducting detectors capable of counting single photons and measuring their energy in the UV, optical, and near-IR. MKIDs feature intrinsic frequency domain multiplexing (FDM) at microwave frequencies, allowing the construction and readout of large arrays. Due to the microwave FDM, MKIDs do not require the complex cryogenic multiplexing electronics used for similar detectors, such as transition edge sensors, but instead transfer this complexity to room temperature electronics where they present a formidable signal processing challenge. In this paper, we describe the first successful effort to build a readout for a photon counting optical/near-IR astronomical instrument, the ARray Camera for Optical to Near-infrared Spectrophotometry. This readout is based on open source hardware developed by the Collaboration for Astronomy Signal Processing and Electronics Research. Designed principally for radio telescope backends, it is flexible enough to be used for a variety of signal processing applications. PMID:22559560

  10. Experimental realization of a metamaterial detector focal plane array.

    PubMed

    Shrekenhamer, David; Xu, Wangren; Venkatesh, Suresh; Schurig, David; Sonkusale, Sameer; Padilla, Willie J

    2012-10-26

    We present a metamaterial absorber detector array that enables room-temperature, narrow-band detection of gigahertz (GHz) radiation in the S band (2-4 GHz). The system is implemented in a commercial printed circuit board process and we characterize the detector sensitivity and angular dependence. A modified metamaterial absorber geometry allows for each unit cell to act as an isolated detector pixel and to collectively form a focal plane array . Each pixel can have a dedicated microwave receiver chain and functions together as a hybrid device tuned to maximize the efficiency of detected power. The demonstrated subwavelength pixel shows detected sensitivity of -77 dBm, corresponding to a radiation power density of 27 nW/m(2), with pixel to pixel coupling interference below -14 dB at 2.5 GHz. PMID:23215222

  11. Applications of pyroelectric materials in array-based detectors.

    PubMed

    Holden, Anthony J

    2011-09-01

    The development of low-cost, uncooled (room temperature operation) thermal detector arrays has been accelerating in recent years and now commercial products are becoming widely available. As costs come down and volumes rise, these devices are entering the consumer marketplace, providing everything from sophisticated security and people-monitoring devices to hand-held thermal imagers for preventative maintenance and building inspection. Two technologies have established significant market shares in uncooled thermal detector array products. These are resistive microbolometers and pyroelectric ceramics. To address the true mass market, the pyroelectric arrays offer significant cost advantage. In this paper, recent developments in a variety of products based on pyroelectric ceramic arrays are described and their performance and applicability are compared and contrasted with competing technologies. This includes the use of low-element-count arrays for applications in people counting and queue measurement, and the drive for cost-effective imaging arrays for mass-market thermal imaging. The technical challenges in materials production, device development, and low-cost manufacture are reviewed and future opportunities and challenges are outlined. PMID:21937335

  12. Microuidic integration on detector arrays for absorption and uorescence micro-spectrometers

    E-print Network

    Quake, Stephen R.

    -channel spectrometers de畁ed on complementary metal oxide semiconductor (CMOS) silicon detector arrays can be usedMicro痷idic integration on detector arrays for absorption and 痷orescence micro-spectrometers Mark micro-channels with 甽tered silicon detector arrays. Elastomers are excellent transparent materials

  13. New approach to detector array receiver performance analysis for laser satellite communication

    Microsoft Academic Search

    Eyal Kayton; Daniel M. Marom; Shlomi Arnon

    2002-01-01

    Laser satellite communication is one of the most promising methods of communication outside the earth's atmosphere. In the continuing quest to optimize atmospheric optical wireless communication, arrays of photodetectors are replacing solitary photodetectors in receivers, affording the advantages of the small fast photodiode while effectively increasing the receiver aperture. Thus, power dispersed by atmospheric turbulence and scattering may be collected

  14. Order-sorting filter transmittance measured with an array detector

    NASA Technical Reports Server (NTRS)

    Heaney, James B.; Bradley, Scott E.; Bly, Vincent T.; Ewin, Audrey J.; La, Anh T.

    1993-01-01

    The simultaneous measurement of the spectrally and spatially variant transmittance of a linear variable order-sorting filter in a manner that closely resembles its conditions of actual use is described. The transmittance of a prototype order-sorting filter was measured in the 400- to 880-nm wavelength region by illuminating it with the output beam of a spectrophotometer while the filter was attached to the front of a 30 x 32 pixel silicon array detector. The filter was designed to be used in the output beam of a grating spectrometer to prevent the dispersal of higher diffracted orders onto an array detector. Areas of the filter that were spatially matched to the corresponding detector pixel column had measured peak transmittances of about 90 percent that were uniform to within +/- 1.5 percent along a given column. Transmittances for incident wavelengths shorter than the desired bandpass, corresponding to the order overlap region, were measured in the 0.003 range. Line spread function measurements made with the array detector indicated no significant beam spreading caused by inserting the filter into the beam.

  15. Short wave infrared InGaAs focal plane arrays detector: the performance optimization of photosensitive element

    NASA Astrophysics Data System (ADS)

    Gao, Xin-jiang; Tang, Zun-lie; Zhang, Xiu-chuan; Chen, Yang; Jiang, Li-qun; Cheng, Hong-bing

    2009-07-01

    Significant progress has been achieved in technology of the InGaAs focal plane arrays (FPA) detector operating in short wave infrared (SWIR) last two decades. The no cryogenic cooling, low manufacturing cost, low power, high sensitivity and maneuverability features inherent of InGaAs FPA make it as a mainstream SWIR FPA in a variety of critical military, national security, aerospace, telecommunications and industrial applications. These various types of passive image sensing or active illumination image detecting systems included range-gated imaging, 3-Dimensional Ladar, covert surveillance, pulsed laser beam profiling, machine vision, semiconductor inspection, free space optical communications beam tracker, hyperspectroscopy imaging and many others. In this paper the status and perspectives of hybrid InGaAs FPA which is composed of detector array (PDA) and CMOS readout integrate circuit (ROIC) are reviewed briefly. For various low light levels applications such as starlight or night sky illumination, we have made use of the interface circuit of capacitive feedback transimpedance amplifier (CTIA) in which the integration capacitor was adjustable, therefore implements of the physical and electrical characteristics matches between detector arrays and readout intergrate circuit was achieved excellently. Taking into account the influences of InGaAs detector arrays' optoelectronic characteristics on performance of the FPA, we discussed the key parameters of the photodiode in detailed, and the tradeoff between the responsivity, dark current, impedance at zero bias and junction capacitance of photosensitive element has been made to root out the impact factors. As a result of the educed approach of the photodiode's characteristics optimizing which involve with InGaAs PDA design and process, a high performance InGaAs FPA of 30um pixel pitch and 320256 format has been developed of which the response spectrum range over 0.9um to 1.7um, the mean peak detectivity (?=1.55?m) was 61012 cmHz1/2W-1 and dynamics range reached 68 dB at room temperature. Making use of the fabricated 320256 InGaAs FPA, the concerning objects can be imaged in the low light level or nightglow background.

  16. Testing and characterization of the CYCLOPS HgCdTe focal plane detector array

    NASA Astrophysics Data System (ADS)

    Poropat, G. V.

    1993-08-01

    Optoelectronics Division has developed an advanced technology demonstrator utilizing an infrared focal plane detector array to assess the feasibility of using passive infrared sensors for ADF applications. To model the performance of the sensor the characteristics of the focal plane detector array have been measured. The measurement of the characteristics of large scale detector arrays and the testing of these arrays present problems which are not encountered with single element infrared detectors. Optoelectronics Division has gained considerable experience in these processes during the development of the 'Cyclops' technology demonstrator. The procedures used in characterizing the HgCdTe focal plane detector array and the results obtained are described.

  17. New results from the Antarctic Muon And Neutrino Detector Array

    NASA Astrophysics Data System (ADS)

    AMANDA Collaboration; Ackermann, M.; Ahrens, J.; Albrecht, H.; Atlee, D. W.; Bai, X.; Bay, R.; Bartelt, M.; Barwick, S. W.; Becka, T.; Becker, K.-H.; Becker, J. K.; Bernardini, E.; Bertrand, D.; Boersma, D. J.; B鰏er, S.; Botner, O.; Bouchta, A.; Bouhali, O.; Braun, J.; Burgess, C.; Burgess, T.; Castermans, T.; Chirkin, D.; Coarasa, J. A.; Collin, B.; Conrad, J.; Cooley, J.; Cowen, D. F.; Davour, A.; de Clercq, C.; De Young, T.; Desiati, P.; Ekstr鰉, P.; Feser, T.; Gaisser, T. K.; Ganugapati, R.; Geenen, H.; Gerhardt, L.; Goldschmidt, A.; Gro, A.; Hallgren, A.; Halzen, F.; Hanson, K.; Hardtke, D.; Hardtke, R.; Harenberg, T.; Hauschildt, T.; Helbing, K.; Hellwig, M.; Herquet, P.; Hill, G. C.; Hodges, J.; Hubert, D.; Hughey, B.; Hulth, P. O.; Hultqvist, K.; Hundertmark, S.; Jacobsen, J.; Kampert, K.-H.; Karle, A.; Kelley, J.; Kestel, M.; K鰌ke, L.; Kowalski, M.; Krasberg, M.; Kuehn, K.; Leich, H.; Leuthold, M.; Lundberg, J.; Madsen, J.; Mandli, K.; Marciniewski, P.; Matis, H. S.; McParland, C. P.; Messarius, T.; Minaeva, Y.; Mio?inovi?, P.; Morse, R.; M黱ich, K.; Nahnhauer, R.; Nam, J. W.; Neunh鰂fer, T.; Niessen, P.; Nygren, D. R.; 謌elman, H.; Olbrechts, Ph.; P閞ez de Los Heros, C.; Pohl, A. C.; Porrata, R.; Price, P. B.; Przybylski, G. T.; Rawlins, K.; Resconi, E.; Rhode, W.; Ribordy, M.; Richter, S.; Rodr韌uez Martino, J.; Sander, H.-G.; Schinarakis, K.; Schlenstedt, S.; Schneider, D.; Schwarz, R.; Seo, S. H.; Silvestri, A.; Solarz, M.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Steele, D.; Steffen, P.; Stokstad, R. G.; Sulanke, K.-H.; Taboada, I.; Tarasova, O.; Thollander, L.; Tilav, S.; Vandenbroucke, J.; Voicu, L. C.; Wagner, W.; Walck, C.; Walter, M.; Wang, Y. R.; Wiebusch, C. H.; Wischnewski, R.; Wissing, H.; Woschnagg, K.; Yodh, G.

    2005-06-01

    We present recent results from the Antarctic Muon And Neutrino Detector Array (AMANDA) on searches for high-energy neutrinos of extraterrestrial origin. We have searched for a diffuse flux of neutrinos, neutrino point sources and neutrinos from GRBs and from WIMP annihilations in the Sun or the center of the Earth. We also present a preliminary result on the first energy spectrum above a few TeV for atmospheric neutrinos.

  18. A 90 element CdTe array detector

    Microsoft Academic Search

    Y. Iwase; M. Funaki; A. Onozuka; M. Ohmori

    1992-01-01

    The fabrication of a CdTe array radiation detector and its radiation detection characteristics are described. In order to obtain high efficiency of charge collection and realize uniform detection sensitivity, current-voltage characteristics with the combination of large and small barrier height contacts and three kinds of CdTe crystals have been investigated. It was found that the Schottky barrier height of electroless

  19. Distributed Antenna-Coupled TES for FIR Detectors Arrays

    NASA Technical Reports Server (NTRS)

    Day, Peter K.; Leduc, Henry G.; Dowell, C. Darren; Lee, Richard A.; Zmuidzinas, Jonas

    2007-01-01

    We describe a new architecture for a superconducting detector for the submillimeter and far-infrared. This detector uses a distributed hot-electron transition edge sensor (TES) to collect the power from a focal-plane-filling slot antenna array. The sensors lay directly across the slots of the antenna and match the antenna impedance of about 30 ohms. Each pixel contains many sensors that are wired in parallel as a single distributed TES, which results in a low impedance that readily matches to a multiplexed SQUID readout These detectors are inherently polarization sensitive, with very low cross-polarization response, but can also be configured to sum both polarizations. The dual-polarization design can have a bandwidth of 50The use of electron-phonon decoupling eliminates the need for micro-machining, making the focal plane much easier to fabricate than with absorber-coupled, mechanically isolated pixels. We discuss applications of these detectors and a hybridization scheme compatible with arrays of tens of thousands of pixels.

  20. Imaging MAMA detector systems. [Multi-Anode Microchannel Array

    NASA Technical Reports Server (NTRS)

    Slater, David C.; Timothy, J. G.; Morgan, Jeffrey S.; Kasle, David B.

    1990-01-01

    Imaging multianode microchannel array (MAMA) detector systems with 1024 x 1024 pixel formats have been produced for visible and UV wavelengths; the UV types employ 'solar blind' photocathodes whose detective quantum efficiencies are significantly higher than those of currently available CCDs operating at far-UV and EUV wavelengths. Attention is presently given to the configurations and performance capabilities of state-of-the-art MAMA detectors, with a view to the development requirements of the hybrid electronic circuits needed for forthcoming spacecraft-sensor applications. Gain, dark noise, uniformity, and dynamic range performance data are presented for the curved-channel 'chevron', 'Z-plate', and helical-channel high gain microchannel plate configurations that are currently under evaluation with MAMA detector systems.

  1. The Telescope Array Middle Drum fluorescence detector simulation on GPUs

    NASA Astrophysics Data System (ADS)

    Abu-Zayyad, Tareq; Telescope-Array Collaboration

    2014-06-01

    In recent years, the Graphics Processing Unit (GPU) has been recognized and widely used as an accelerator for many scientific calculations. In general, problems amenable to parallelization are ones that benefit most from the use of GPUs. The Monte Carlo simulation of fluorescence detector response to air showers presents many opportunities for parallelization. In this paper we report on a Monte Carlo program used for the simulation of the Telescope Array Fluorescence Detector located at the Middle Drum site which uses GPU acceleration. All of the physics simulation from shower development, light production and atmospheric attenuation, as well as, the realistic detector optics and electronics simulations are done on the GPU. A detailed description of the code implementation is given, and results on the accuracy and performance of the simulation are presented as well. Improvements in computational throughput in excess of 50 are reported and the accuracy of the results is on par with the CPU implementation of the simulation.

  2. Ultraviolet spectroscopy of Comet Austin (1989c1) using a two-dimensional diode array detector

    NASA Astrophysics Data System (ADS)

    Sahnow, David James

    A two-dimensional, photon-counting intensified photodiode array detector has been constructed and successfully tested in the laboratory and on a spectrograph in three sounding rocket flights. The detector is an extension of the one-dimensional intensified diode array detector used in the Hopkins Ultraviolet Telescope. Extensive laboratory measurements have shown that it can successfully centroid with sub-diode resolution, and can be used in place of ranicon detectors to measure the spectra of faint objects. The instrument successfully obtained long slit far-ultraviolet spectra (1250-1850 A) of Comet Austin (1989 c1) on 21 April 1990. Emissions of OI, CI, SI and CO were detected during the 270 seconds of data acquisition. The spectral resolution was 5.5 A, while the spatial resolution was limited by pointing jitter to approximately 30 arcseconds. The spatial profiles of the carbon and oxygen emissions show narrow enhancements which are suggestive of a cometary outburst which occurred 15-20 hours before the observation. The overall shape of the atomic carbon profile is similar to those measured during two observations of Comet Halley (1986 III), and is similarly incompatible with photodissociation of CO as its primary source, as determined by model calculations. The CO profile, however, is consistent with that of a parent molecule evaporating directly from the nucleus, with a production rate of 4 plus or minus 1 x 1027 molecules s-1. The O I lambda 1304 emission, also similar in spatial shape to that detected in Halley, includes a contribution due to Bowen fluorescence induced by solar HI Lyman-beta, and its profile can be understood as that due to the photodissociation of H2O, with a production rate of 6.2 plus or minus 0.3 x 1028 molecules s-1, giving an abundance of CO relative to water of 6.5 percent. Spatial profiles of SI lambda 1814 were also obtained, with profiles attributable to that of a daughter product of short-lived species such as CS2 and H2S.

  3. Multicolor focal plane array detector technology: a review

    NASA Astrophysics Data System (ADS)

    Abedin, M. Nurul; Refaat, Tamer F.; Zawodny, Joseph M.; Sandford, Steve P.; Singh, Upendra N.; Bandara, Sumith V.; Gunapala, Sarath D.; Bhat, Ishwara; Barnes, Norman P.

    2003-11-01

    A major concern today is to accurately measure CO2, O3, H2O, and CH4 in the atmosphere for the prediction of climate and weather. These measurements are critical for understanding the Earth's atmosphere, atmospheric chemistry, and systemic forcing driving climactic changes. For these measurements, detectors with high quantum efficiency and near background limited performance detectivity over a wide wavelength range are necessary. In this article, we will review the state-of-the-art single and multicolor detector technologies in a wide spectral-range, for use in space-based and airborne remote sensing applications. Simultaneous detection in multi-wavelength bands with a single focal plane array (FPA) will result in reduction or elimination of heavy and complex optical components now required for wavelength differentiation in atmospheric remote sensors leading to smaller, lighter, simpler instruments with higher performance. Discussions are focused on current and the most recently developed FPA in addition to emphasizing future development in UV-to-Far infrared multicolor FPA detectors for next generation space-based instruments to measure water vapor and greenhouse gases. This novel detector component will make instruments designed for these critical measurements more efficient while reducing complexity and associated electronics and weight. Finally, we will discuss the on-going detector technology efforts at NASA Langley Research Center (LaRC), Jet Propulsion Laboratory (JPL), and Rensselaer Polytechnic Institute (RPI).

  4. Polarization-dependent sensing of a self-assembled monolayer using biaxial nanohole arrays

    E-print Network

    Brolo, Alexandre G.

    on local refractive index changes at the surface of a noble metal is the physical mechanism explored in SPR of sensing applications are underway.9,1315 Other than SPR sensing, subwavelength hole arrays in metal films a photodiode or detector array to detect transmission. It is more straightforward to integrate a laser/detector

  5. Dual APD array readout of LSO crystals: optimization of crystal surface treatment

    Microsoft Academic Search

    Y. Shao; K. Meadors; R. W. Silverman; R. Farrell; L. Cirignano; R. Grazioso; K. S. Shah; S. R. Cherry

    2002-01-01

    We are developing a compact positron emission tomography (PET) detector module with a depth of interaction capability (DOI) based on a lutetium oxyorthosilicate (LSO) scintillator array coupled at both ends by avalanche photodiode (APD) arrays. This leads to a detector with high sensitivity that can provide high and uniform image resolution. We report studies on improving the DOI resolution by

  6. Fast, High-Precision Readout Circuit for Detector Arrays

    NASA Technical Reports Server (NTRS)

    Rider, David M.; Hancock, Bruce R.; Key, Richard W.; Cunningham, Thomas J.; Wrigley, Chris J.; Seshadri, Suresh; Sander, Stanley P.; Blavier, Jean-Francois L.

    2013-01-01

    The GEO-CAPE mission described in NASA's Earth Science and Applications Decadal Survey requires high spatial, temporal, and spectral resolution measurements to monitor and characterize the rapidly changing chemistry of the troposphere over North and South Americas. High-frame-rate focal plane arrays (FPAs) with many pixels are needed to enable such measurements. A high-throughput digital detector readout integrated circuit (ROIC) that meets the GEO-CAPE FPA needs has been developed, fabricated, and tested. The ROIC is based on an innovative charge integrating, fast, high-precision analog-to-digital circuit that is built into each pixel. The 128128-pixel ROIC digitizes all 16,384 pixels simultaneously at frame rates up to 16 kHz to provide a completely digital output on a single integrated circuit at an unprecedented rate of 262 million pixels per second. The approach eliminates the need for off focal plane electronics, greatly reducing volume, mass, and power compared to conventional FPA implementations. A focal plane based on this ROIC will require less than 2 W of power on a 11-cm integrated circuit. The ROIC is fabricated of silicon using CMOS technology. It is designed to be indium bump bonded to a variety of detector materials including silicon PIN diodes, indium antimonide (InSb), indium gallium arsenide (In- GaAs), and mercury cadmium telluride (HgCdTe) detector arrays to provide coverage over a broad spectral range in the infrared, visible, and ultraviolet spectral ranges.

  7. An MLC calibration method using a detector array

    SciTech Connect

    Simon, Thomas A.; Kahler, Darren; Simon, William E.; Fox, Christopher; Li, Jonathan; Palta, Jatinder; Liu, Chihray [Department of Nuclear and Radiological Engineering, University of Florida, 202 Nuclear Science Building, Gainesville, Florida 32611-8300 (United States); Sun Nuclear Corporation, 425-A Pineda Court, Melbourne, Florida 32940 (United States) and Department of Radiation Oncology, Health Science Center, University of Florida, P.O. Box 100385, Gainesville, Florida 32610-0385 (United States); Department of Radiation Oncology, Health Science Center, University of Florida, P.O. Box 100385, Gainesville, Florida 32610-0385 (United States); Sun Nuclear Corporation, 425-A Pineda Court, Melbourne, Florida 32940 (United States); Department of Radiation Oncology, Tulane University, 1415 Tulane Ave, HC65, New Orleans, Louisiana 70112 (United States); Department of Radiation Oncology, Health Science Center, University of Florida, P.O. Box 100385, Gainesville, Florida 32610-0385 (United States)

    2009-10-15

    Purpose: The authors have developed a quantitative calibration method for a multileaf collimator (MLC) which measures individual leaf positions relative to the MLC backup jaw on an Elekta Synergy linear accelerator. Methods: The method utilizes a commercially available two-axis detector array (Profiler 2; Sun Nuclear Corporation, Melbourne, FL). To calibrate the MLC bank, its backup jaw is positioned at the central axis and the opposing jaw is retracted to create a half-beam configuration. The position of the backup jaws field edge is then measured with the array to obtain what is termed the radiation defined reference line. The positions of the individual leaf ends relative to this reference line are then inferred by the detector response in the leaf end penumbra. Iteratively adjusting and remeasuring the leaf end positions to within specifications completes the calibration. Using the backup jaw as a reference for the leaf end positions is based on three assumptions: (1) The leading edge of an MLC leaf bank is parallel to its backup jaw's leading edge, (2) the backup jaw position is reproducible, and (3) the measured radiation field edge created by each leaf end is representative of that leaf's position. Data from an electronic portal imaging device (EPID) were used in a similar analysis to check the results obtained with the array. Results: The relative leaf end positions measured with the array differed from those measured with the EPID by an average of 0.11 {+-}0.09 mm per leaf. The maximum leaf positional change measured with the Profiler 2 over a 3 month period was 0.51 mm. A leaf positional accuracy of {+-}0.4 mm is easily attainable through the iterative calibration process. The method requires an average of 40 min to measure both leaf banks. Conclusions: This work demonstrates that the Profiler 2 is an effective tool for efficient and quantitative MLC quality assurance and calibration.

  8. Undersampling Correction for Array Detector-Based Satellite Spectrometers

    NASA Technical Reports Server (NTRS)

    Chance, Kelly; Kurosu, Thomas P.; Sioris, Christopher E.

    2004-01-01

    Array detector-based instruments are now fundamental to measurements of ozone and other atmospheric trace gases from space in the ultraviolet, visible, and infrared. The present generation of such instruments suffers, to a greater or lesser degree, from undersampling of the spectra, leading to difficulties in the analysis of atmospheric radiances. We provide extended analysis of the undersampling suffered by modem satellite spectrometers, which include Global Ozone Monitoring Experiment (GOME), Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY), Ozone Monitoring Instrument (OMI), and Ozone Mapping and Profiler Suite (OMPS). The analysis includes basic undersampling, the effects of binning into separate detector pixels, and the application of high-resolution Fraunhofer spectral data to correct for undersampling in many useful cases.

  9. A three wavelength infrared focal plane array detector element

    Microsoft Academic Search

    Dong-Su Kim; Stephen R. Forrest; Michael J. Lange; Gregory H. Olsen; Marshall J. Cohen

    1994-01-01

    We have demonstrated a novel three wavelength InGaAs focal plane array pixel element for detection at wavelengths from 0.9-2.6 ?m, where each of three wavelength sensitive detectors are individually addressable. This device consists of successively smaller bandgap layers of InxGa1-xAs (x⩾0.53), separated by compositionally graded layers of InAsyP1-y to decrease defects induced by lattice mismatch strain with the InP substrate.

  10. Design of HgCdTe heterojunction photodiodes on Si substrate

    NASA Astrophysics Data System (ADS)

    Zhang, P.; Ye, Z. H.; Chen, Y. Y.; Lin, C.; Hu, X. N.; Ding, R. J.; He, L.

    2014-05-01

    An innovative heterojunction photodiode structure in HgCdTe-on-Si long-wavelength (LW) infrared focal plane array (IRFPA) detector is investigated in this paper. The quantum efficiency and the photoresponse of devices have been numerically simulated, using Crosslight Technology Computer Aided Design (TCAD) software. Simulation results indicate that in contrast to the p+-on-n homojunction photodiode, the heterojunction photodiode effectively suppresses the crosstalk between adjacent pixels and interface recombination between HgCdTe active region and buffer layer on Si substrate. And in the range of the LW-band, the quantum efficiency of the heterojunction photodiode increases by 35.5%. Furthermore, the heterojunction photodiode acquires the narrow-band response spectrum desired in the application of the LW IRFPA detectors as the p+-on-n homojunction photodiode with the optical filter. Finally, the smaller bulk resistance of its heavily doped N-type layer ensures the uniformity of the pixel series resistance in the large format IRFPAs.

  11. Crystal Identification In Modular Array Detectors For High Spatial Resolution PET

    NASA Astrophysics Data System (ADS)

    Weinberg, Irving N.; Dahlbom, Magnus; Ricci, Anthony; Hoffman, Edward J.

    1986-01-01

    The use of detector arrays in PET has been proposed and studied as a economical means of obtaining very high resolution images. The properties of detector arrays for use in high resolution PET scanners were investigated. Analytical approximations and Monte Carlo simulations were used to design detector arrays consisting of six to eight crystals coupled to two photomultipliers to allow identification of the individual crystals. Arrays of 2.85 mm thick crystals of Bismuth Germanate (BGO), Gadolinium Orthosilicate (GSO), and Barium Fluoride (BaF2) were examined. The effect of interdetector materials such as lead, and plastic on positioning accuracy was tested. Assembled arrays of six 2.85 mm thick BG0 crystals yielded line spread function FWHMs of 2.4 to 3.2 millimeters. The limiting resolution of detector arrays was found to be defined by the scintillation light yield of the crystals, the light gathering efficiency of the detector arrays, and the fraction of interdetector scatter.

  12. Multiplexed detector arrays for 1.55-1.7 microns imaging

    NASA Astrophysics Data System (ADS)

    Moy, J. P.; Rebondy, J.; Reboul, J.-P.; Villard, M.; Kazmiersky, K.

    1985-10-01

    The design features of the photodiodes, readout circuit and assembly of the SPOT III short wave IR scanner for vegetation and soil moisture measurements are discussed. InGaAs photodiodes on an InP substrate have been manufactured in arrays of several hundred elements using chemical vapor deposition methods. This technology features diffused epitaxy-formed wafers wire-cut into elements placed along two staggered lines of 30 x 50 sq microns mesas with a 2 microns pitch. A dark current density of -1 V has been obtained in the 1/100,000 A/sq cm range over a narrow temperature range. Arrays of 300 elements have exhibited satisfactory sensitivity in the 1.55-1.70 micron interval. The elements are connected to the CCD lateral inputs by means of wedge-bonding. In operation, 150 elements will be accessed in the vidicon mode.

  13. The hybrid energy spectrum of Telescope Array's Middle Drum Detector and surface array

    NASA Astrophysics Data System (ADS)

    Abbasi, R. U.; Abe, M.; Abu-Zayyad, T.; Allen, M. G.; Anderson, R.; Azuma, R.; Barcikowski, E.; Belz, J. W.; Bergman, D. R.; Blake, S. A.; Cady, R.; Chae, M. J.; Cheon, B. G.; Chiba, J.; Chikawa, M.; Cho, W. R.; Fujii, T.; Fukushima, M.; Goto, T.; Hanlon, W.; Hayashi, Y.; Hayashida, N.; Hibino, K.; Honda, K.; Ikeda, D.; Inoue, N.; Ishii, T.; Ishimori, R.; Ito, H.; Ivanov, D.; Jui, C. C. H.; Kadota, K.; Kakimoto, F.; Kalashev, O.; Kasahara, K.; Kawai, H.; Kawakami, S.; Kawana, S.; Kawata, K.; Kido, E.; Kim, H. B.; Kim, J. H.; Kim, J. H.; Kitamura, S.; Kitamura, Y.; Kuzmin, V.; Kwon, Y. J.; Lan, J.; Lim, S. I.; Lundquist, J. P.; Machida, K.; Martens, K.; Matsuda, T.; Matsuyama, T.; Matthews, J. N.; Minamino, M.; Mukai, K.; Myers, I.; Nagasawa, K.; Nagataki, S.; Nakamura, T.; Nonaka, T.; Nozato, A.; Ogio, S.; Ogura, J.; Ohnishi, M.; Ohoka, H.; Oki, K.; Okuda, T.; Ono, M.; Oshima, A.; Ozawa, S.; Park, I. H.; Pshirkov, M. S.; Rodriguez, D. C.; Rubtsov, G.; Ryu, D.; Sagawa, H.; Sakurai, N.; Sampson, A. L.; Scott, L. M.; Shah, P. D.; Shibata, F.; Shibata, T.; Shimodaira, H.; Shin, B. K.; Shin, H. S.; Smith, J. D.; Sokolsky, P.; Springer, R. W.; Stokes, B. T.; Stratton, S. R.; Stroman, T. A.; Suzawa, T.; Takamura, M.; Takeda, M.; Takeishi, R.; Taketa, A.; Takita, M.; Tameda, Y.; Tanaka, H.; Tanaka, K.; Tanaka, M.; Thomas, S. B.; Thomson, G. B.; Tinyakov, P.; Tkachev, I.; Tokuno, H.; Tomida, T.; Troitsky, S.; Tsunesada, Y.; Tsutsumi, K.; Uchihori, Y.; Udo, S.; Urban, F.; Vasiloff, G.; Wong, T.; Yamane, R.; Yamaoka, H.; Yamazaki, K.; Yang, J.; Yashiro, K.; Yoneda, Y.; Yoshida, S.; Yoshii, H.; Zollinger, R.; Zundel, Z.

    2015-08-01

    The Telescope Array experiment studies ultra high energy cosmic rays using a hybrid detector. Fluorescence telescopes measure the longitudinal development of the extensive air shower generated when a primary cosmic ray particle interacts with the atmosphere. Meanwhile, scintillator detectors measure the lateral distribution of secondary shower particles that hit the ground. The Middle Drum (MD) fluorescence telescope station consists of 14 telescopes from the High Resolution Fly's Eye (HiRes) experiment, providing a direct link back to the HiRes measurements. Using the scintillator detector data in conjunction with the telescope data improves the geometrical reconstruction of the showers significantly, and hence, provides a more accurate reconstruction of the energy of the primary particle. The Middle Drum hybrid spectrum is presented and compared to that measured by the Middle Drum station in monocular mode. Further, the hybrid data establishes a link between the Middle Drum data and the surface array. A comparison between the Middle Drum hybrid energy spectrum and scintillator Surface Detector (SD) spectrum is also shown.

  14. An LSO scintillator array for a PET detector module with depth of interaction measurement

    Microsoft Academic Search

    J. S. Huber; W. W. Moses; M. S. Andreaco; O. Petterson

    2001-01-01

    Presents construction methods and performance results for a production scintillator array of 64 optically isolated, 3 mm3 mm30 mm sized LSO crystals. This scintillator array has been developed for a PET detector module consisting of the 88 LSO array coupled on one end to a single photomultiplier tube (PMT) and on the opposite end to a 64 pixel array of

  15. A YSO\\/LSO phoswich array detector for single and coincidence photon imaging

    Microsoft Academic Search

    M. Dahlbom; L. R. MacDonald; M. Schmand; L. Eriksson; M. Andreaco; C. Williams

    1998-01-01

    The performance of a phoswich array detector module for possible use in a combined single and coincidence photon imaging system has been evaluated. The detector consist of a linear array of discrete 4󫶕5 mm3 YSO elements coupled to a combined detector array\\/light guide of LSO, 10 mm thick. Since the scintillation light decay time is different in YSO and LSO

  16. Analysis of 12 different pentacyclic triterpenic acids from frankincense in human plasma by high-performance liquid chromatography and photodiode array detection.

    PubMed

    B點hele, Berthold; Simmet, Thomas

    2003-10-01

    For the determination of pentacyclic triterpenes of the boswellic acid family in human plasma a novel sensitive method was developed combining serial extraction on diatomaceous earth and graphitized carbon black followed by reversed phase high-performance liquid chromatography (HPLC) and photodiode array detection. The overall average extraction yield of 12 different pentacyclic triterpenic acids was approximately 66%. The calibration graphs were linear with coefficients of correlation for all compounds greater than 0.999. The overall within-day and between-day coefficients of variation (CV) for the 12 pentacyclic triterpenic acids were 5.6 and 6.8%, respectively. This HPLC procedure delivers the analytical sensitivity, precision and accuracy required for clinical pharmacokinetic and therapeutic studies. PMID:14522040

  17. Optimal extraction and fingerprint analysis of Cnidii fructus by accelerated solvent extraction and high performance liquid chromatographic analysis with photodiode array and mass spectrometry detections.

    PubMed

    Gao, Fangyuan; Hu, Yongsheng; Ye, Xiaolan; Li, Ji; Chen, Zhao; Fan, Guorong

    2013-12-01

    A confirmatory and reliable procedure has been developed for extraction and determination of Cnidii fructus by accelerated solvent extraction (ASE) and high-performance liquid chromatography coupled with photodiode array, electrospray ionisation ion trap tandem mass spectrometry and time of flight mass spectrometry (HPLC-PDA-ESI-ITMS(n)/TOF-MS). The determination method enabled the characterisation of sixteen bioactive components in C. fructus and quantification of three major coumarins, namely osthole, imperatorin and isopimpinellin. Response surface methodology (RSM) was employed to optimise the extraction parameters yielding the optimum conditions of ASE (extraction temperature 122 癈, extraction time 5 min and two static cycles). And the total contents of three major coumarins extracted by ASE under the optimum conditions was significantly higher than those by reflux and ultrasonic extraction (P<0.05) with better reproducibility. At last, the proposed method coupled with pattern recognition was applied to analysis of C. fructus from eight different regions in China. PMID:23870916

  18. Excess noise in GaAs and AlGaAs avalanche photodiodes with GaSb absorption regions梒omposite structures grown using interfacial misfit arrays

    NASA Astrophysics Data System (ADS)

    Craig, A. P.; Reyner, C. J.; Marshall, A. R. J.; Huffaker, D. L.

    2014-05-01

    Interfacial misfit arrays were embedded within two avalanche photodiode (APD) structures. This allowed GaSb absorption layers to be combined with wide-bandgap multiplication regions, consisting of GaAs and Al0.8Ga0.2As, respectively. The GaAs APD represents the simplest case. The Al0.8Ga0.2As APD shows reduced dark currents of 5.07 ?Acm-2 at 90% of the breakdown voltage, and values for effective k =?/? below 0.2. Random-path-length modeled excess noise is compared with experimental data, for both samples. The designs could be developed further, allowing operation to be extended to longer wavelengths, using other established absorber materials which are lattice matched to GaSb.

  19. Ultra-performance LC-photodiode array-e?-ESI-MS/MS screening method for the detection of radical-scavenging natural antioxidants from radix et rhizoma Rhei.

    PubMed

    Wang, Guo-Ying; Chen, Fang-Fang; Shi, Yan-Ping

    2011-02-01

    A novel ultra-performance LC-photodiode array-el-ESI-MS/MS screening method was developed for the detection and identification of natural antioxidants from radix et rhizoma Rhei. Nine compounds were found to possess a potential antioxidant activity, and their free radical-scavenging capacities were investigated in detail. The nine compounds were identified as 1-O-galloyl-2-O-cinnamoylglucose, 6-hydroxymusizin-8-O-?-D-glucopyranoside, (+)-catechin, gallic acid 3-O-?-D-glucopyranoside, trans-3,5,4'-trihydroxystilbene- 4'-O-?-D-(2"-O-galloyl)-glucopyranoside, sennoside A, 4-(4'-hydroxyphenyl)-2- butanone-4'-O-?-D-(2"-O-galloyl-6"-O-p-coumaroyl) glucopyranoside, emodin-8-O-(6'-Omalonyl) glucopyranoside, and physcion-8-O-?-D-glucopyranoside. The reactivity and SC(50) values of those compounds were investigated, respectively. 1-O-Galloyl-2-O-cinnamoylglucose showed the strongest capability for scavenging 1,1-diphenyl-2-picrylhydrazylfree radical; trans-3,5,4'-trihydroxystilbene-4'-O-?-D-(2"-O-galloyl) glucopyranoside showed the strongest capability for scavenging superoxide radical; 4-(4'-hydroxyphenyl)-2-butanone- 4'-O-2-D-(2"-O-galloyl-6"-O-p-coumaroyl) glucopyranoside exhibited the highest reactivity in the lipid peroxidation processes. The use of the analytical screening method based on ultra-performance LC-photodiode array-el-ESI-MS/MS would provide a new way for rapid detection of radical-scavenging natural compounds from radix et rhizoma Rhei or complex matrices. PMID:21268249

  20. Separation and measurement of clofibroyl coenzyme A and clofibric acid in rat liver after clofibrate adminstration by reversed-phase high-performance liquid chromatography with photodiode array detection.

    PubMed

    Lygre, T; Aarsaether, N; Stensland, E; Aarsland, A; Berge, R K

    1986-08-22

    A method to identify and quantitate clofibric acid and clofibroyl coenzyme A (CoA) products in rat liver was developed using reversed-phase high-performance liquid chromatography. The system was developed with baseline separation of clofibroyl-CoA from clofibric acid using isocratic elution, with a mobile phase consisting of 52% methanol and 28 mM potassium phosphate buffer (pH 4.2). With this high methanol concentration, the large amount of UV-absorbing materials present in the liver extracts were eluted earlier than the investigated compounds. Clofibroyl-CoA has a characteristic absorbance spectrum with distinct peaks at 260 and 230 nm, while clofibric acid showed only a distinct peak at 230 nm. Using an on-line photodiode array detector, the spectra could be recorded during analysis without interrupting the flow of the mobile phase. This spectral analysis identification possibilities and evaluation of the purity of the chromatographic peaks. In a perchloric extract of rat liver, the recovery of clofibric acid and clofibroyl-CoA added to the liver extract ranged from 70 to 80%. A linear relationship was observed between clofibric acid and clofibroyl-CoA concentration and the area of their peaks in the chromatogram. The detection limit of the method was lower than 5 pmol for both compounds when the absorbance was recorded at 230 nm. The method could be used without modification for the estimation of clofibroyl-CoA and clofibric acid in biological extracts. PMID:3771728

  1. Rapid and sensitive high-performance liquid chromatographic method for simultaneous determination of retinol, alpha-tocopherol, 25-hydroxyvitamin D3 and 25-hydroxyvitamin D2 in human plasma with photodiode-array ultraviolet detection.

    PubMed

    Alvarez, J C; De Mazancourt, P

    2001-05-01

    A new rapid and sensitive high-performance liquid chromatographic method using 0.5 ml of plasma has been developed for the simultaneous determination of retinol (vitamin A), alpha-tocopherol (vitamin E), 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3. The eluate was monitored with a photodiode-array detector with two fixed wavelengths (267 nm for vitamin D, 292 nm for alpha-tocopherol and retinol). For all compounds, including internal standards, the method provides extraction recoveries greater than 81%. Detection limits were equal to or lower than 1.5 microg/l for the 4 vitamins. Linearity of standards was excellent (r>0.999 in all cases). Intra-day and inter-day precision were generally acceptable; the intra-dayassay C.V. was 3/4 7.7 for all compounds and the inter-day-assay C.V. was <9.2% except for the lower concentrations of 25-hydroxyvitamin D3, 25-hydroxyvitamin D2 and alpha-tocopherol (10.8, 11.8 and 11.9, respectively). The important properties of the present method are its ease of use, its rapidity, since sample preparation was achieved in 15 min and all the compounds were eluted in less than 15 min, and its small sample volume required (=0.5 ml), which enables it to be used in pediatric practice. PMID:11393696

  2. Spectral x-ray diffraction using a 6 megapixel photon counting array detector

    NASA Astrophysics Data System (ADS)

    Muir, Ryan D.; Pogranichniy, Nicholas R.; Muir, J. Lewis; Sullivan, Shane Z.; Battaile, Kevin P.; Mulichak, Anne M.; Toth, Scott J.; Keefe, Lisa J.; Simpson, Garth J.

    2015-03-01

    Pixel-array array detectors allow single-photon counting to be performed on a massively parallel scale, with several million counting circuits and detectors in the array. Because the number of photoelectrons produced at the detector surface depends on the photon energy, these detectors offer the possibility of spectral imaging. In this work, a statistical model of the instrument response is used to calibrate the detector on a per-pixel basis. In turn, the calibrated sensor was used to perform separation of dual-energy diffraction measurements into two monochromatic images. Targeting applications include multi-wavelength diffraction to aid in protein structure determination and X-ray diffraction imaging.

  3. Development of photodetection system based on multipixel avalanche Geiger photodiodes with WLS for LXe low-background detectors

    NASA Astrophysics Data System (ADS)

    Akimov, D. Yu.; Akindinov, A. V.; Alexandrov, I. S.; Burenkov, A. A.; Danilov, M. V.; Kovalenko, A. G.; Stekhanov, V. N.

    2010-04-01

    A multipixel avalanche Geiger photodiode with a p-terphenyl wavelength shifter in front of it has been tested in the liquid xenon to detect the 175-nm scintillation light. The global detection efficiency of the VUV photons of ~10% is obtained. A photodetection system with sensitivity to sub-keV ionization and few-mm coordinate accuracy is proposed for LXe low-background experiments.

  4. Progress in focal plane array technologies

    NASA Astrophysics Data System (ADS)

    Rogalski, Antoni

    2012-03-01

    Development of focal plane arrays started in seventies last century and has revolutionized imaging systems in the next decades. This paper presents progress in optical detector technology of focal plane arrays during the past twenty years. At the beginning of paper, emphasises are given on integrated detector assembly and cooling requirements of different types of detectors. Next, the classification of two types of detectors (photon detectors and thermal detectors) is done on the basis of their principle of operation. This topic is followed by general overview of focal plane array architectures. The main subject of paper is concentrated on describing of material systems and detectors operated in different spectral ranges. Special attention is given on recent progress in their detector technologies. Discussion is focused mainly on current and the most rapidly developing focal plane arrays including: CdZnTe detectors, AlGaN photodiodes, visible CCD and CMOS imaging systems, HgCdTe heterostructure photodiodes, quantum well AlGaAs/GaAs photoresistors, and thermal detectors. Emphasis is also given on far-infrared and sub-millimetre wave detector arrays. Finally, the outlook for near-future trends in optical detector technologies is presented.

  5. Application of liquid chromatography with mass spectrometry combined with photodiode array detection and tandem mass spectrometry for monitoring pesticides in surface waters.

    PubMed

    Jeannot, R; Sabik, H; Sauvard, E; Genin, E

    2000-05-19

    Liquid chromatography with photodiode array detection (LC-DAD) and liquid chromatography with mass spectrometry (LC-MS) are two techniques that have been widely used in monitoring pesticides and their degradation products in the environment. However, the application of liquid chromatography with tandem mass spectrometry (LC-MS-MS) for such purposes, once considered too costly, is now gaining considerable ground. In this study, we compare these methods for the multi-residue analysis of pesticides in surface waters collected from the central and southeastern regions of France, and from the St. Lawrence River in Canada. Forty-eight pesticides belonging to eight different classes (triazine, amide, phenylurea, triazole, triazinone, benzimidazole, morpholine, phenoxyalkanoic), along with some of their degradation products, were monitored on a regular basis in the surface waters. For LC-MS, we used the electrospray ionization (ESI) interface in the negative ionization mode on acidic pesticides (phenoxyalkanoic, sulfonylurea), and the atmospheric pressure chemical ionization (APCI) interface in the positive ionization mode on the remaining chemicals. Different extraction techniques were employed, including liquid-liquid extraction with dichloromethane, and solid-phase extraction using C18-bonded silica and graphitized carbon black cartridges. Eleven of the target chemicals (desethylatrazine, desisopropylatrazine, atrazine, simazine, terbuthylazine, metolachlor, carbendazime, bentazone, penconazole, diuron and isoproturon) were detected by LC-MS at concentrations ranging from 20 to 900 ng/l in the surface waters from France, and six pesticides (atrazine, desethylatrazine, desisopropylatrazine, cyanazine, simazine and metolachlor) were detected by LC-MS and LC-MS-MS at concentrations ranging from 3 to 52 ng/l in the samples drawn from the St. Lawrence River. There was good correlation between the LC-DAD and LC-MS techniques for 60 samples. The slope of the curves expressing the relationship between the results obtained with LC-DAD versus those obtained by LC-MS was near 1, with a correlation coefficient (r) of over 0.93. The identification potential of the LC-MS technique, however, was greater than that of the LC-DAD; its mass spectra, mainly reflecting the pseudomolecular ion resulting from a protonation or a deprotonation of the molecule, was rich in information. The LC-MS-MS technique with ion trap detectors, tested against the LC-MS on 10 surface water samples, gave results that correlated well with the LC-MS results, albeit generating mass spectra that yielded far more information about the structure of unknown substances. The sensitivity of the LC-MS-MS was equivalent to the selected ion monitoring (SIM) acquisition mode in LC-MS. The detection limits of the target pesticides ranged from 20 to 100 ng/l for the LC-MS technique (under full scan acquisition), and from 2 to 6 ng/l for LC-MS-MS. These limits were improved by a factor of almost 10 by increasing the sample volume to 10 l. PMID:10870695

  6. Assessment study of infrared detector arrays for low-background astronomical research

    NASA Technical Reports Server (NTRS)

    Ando, K. J.

    1978-01-01

    The current state-of-the-art of infrared detector arrays employing charge coupled devices (CCD) or charge injection devices (CID) readout are assessed. The applicability, limitations and potentials of such arrays under the low-background astronomical observing conditions of interest for SIRFT (Shuttle Infrared Telescope Facility) are determined. The following are reviewed: (1) monolithic extrinsic arrays; (2) monolithic intrinsic arrays; (3) charge injection devices; and (4) hybrid arrays.

  7. A multichannel X-ray detector

    Microsoft Academic Search

    H. C. Gerritsen; H. van Brug; F. Bijkerk; M. J. van der Wiel

    1986-01-01

    A multichannel X-ray detector with a spatial resolution of 0.13 mm and a maximum of 200 effective channels is described. The detector consists of a conversion electrode to convert X-rays into electrons, a microchannel-plate\\/phosphor-screen assembly to amplify the electron signal, a self-scanning array containing 1024 photodiodes, and optics to form an image from the phosphor screen on the self-scanning array.

  8. Electrical breakdown gas detector featuring carbon nanotube array electrodes.

    PubMed

    Kim, Seongyul; Pal, Sunil; Ajayan, Pulickel M; Borca-Tasciuc, Theodorian; Koratkar, Nikhil

    2008-01-01

    We demonstrate here detection of dichloro-difluoro-methane and oxygen in mixtures with helium using a carbon nanotube electrical breakdown sensor device. The sensor is comprised of an aligned array of multiwalled carbon nanotubes deposited on a nickel based super-alloy (Inconel 600) as the anode; the counter electrode is a planar nickel sheet. By monitoring the electrical breakdown characteristics of oxygen and dichloro-difluoro-methane in a background of helium, we find that the detection limit for dichloro-difluoro-methane is approximately 0.1% and the corresponding limit for oxygen is approximately 1%. A phenomenologigal model is proposed to describe the trends observed in detection of the two mixtures. These results indicate that carbon nanotube based electrical breakdown sensors show potential as end detectors in gas-chromatography devices. PMID:18468093

  9. Microfluidic integration on detector arrays for absorption and fluorescence micro-spectrometers

    Microsoft Academic Search

    Mark L. Adams; Markus Enzelberger; Stephen Quake; Axel Scherer

    2003-01-01

    We describe a new approach for miniaturizing spectrometers by combining replica molded elastomeric micro-channels with filtered silicon detector arrays. Elastomers are excellent transparent materials, which provide hermetic seals to silicon dioxide and allow sensitive absorption and fluorescent spectroscopy in the visible and near-UV wavelength range. When integrated on dense detector arrays, such spectroscopy can be conducted on picoliter sample volumes.

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

    SciTech Connect

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

    2010-06-01

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

  11. Developing Seedless Growth of ZnO Micro/Nanowire Arrays towards ZnO/FeS2/CuI P-I-N Photodiode Application

    PubMed Central

    Yang, Zhi; Wang, Minqiang; Shukla, Sudhanshu; Zhu, Yue; Deng, Jianping; Ge, Hu; Wang, Xingzhi; Xiong, Qihua

    2015-01-01

    A seedless hydrothermal method is developed to grow high density and vertically aligned ZnO micro/nanowire arrays with low defect density on metal films under the saturated nutrition solution. In particular, the mechanism of seedless method is discussed here. A buffer layer can be confirmed by transmission electron microscopy (TEM), which may release the elastic strain between ZnO and substrate to achieve this highly mismatched heteroepitaxial structures. Based on ZnO micro/nanowire arrays with excellent wettability surface, we prepared ZnO-FeS2-CuI p-i-n photodiode by all-solution processed method with the high rectifying ratio of 197 at 1?V. Under AM 1.5 condition, the Jsc of 0.5?mA/cm2, on-off current ratio of 371 and fast photoresponse at zero bias voltage were obtained. This good performance comes from excellent collection ability of photogenerated electrons and holes due to the increased depletion layer width for p-i-n structure. Finally, the high responsivity around 900?nm shows the potential as near infrared photodetectors applications. PMID:26077658

  12. Developing Seedless Growth of ZnO Micro/Nanowire Arrays towards ZnO/FeS2/CuI P-I-N Photodiode Application.

    PubMed

    Yang, Zhi; Wang, Minqiang; Shukla, Sudhanshu; Zhu, Yue; Deng, Jianping; Ge, Hu; Wang, Xingzhi; Xiong, Qihua

    2015-01-01

    A seedless hydrothermal method is developed to grow high density and vertically aligned ZnO micro/nanowire arrays with low defect density on metal films under the saturated nutrition solution. In particular, the mechanism of seedless method is discussed here. A buffer layer can be confirmed by transmission electron microscopy (TEM), which may release the elastic strain between ZnO and substrate to achieve this highly mismatched heteroepitaxial structures. Based on ZnO micro/nanowire arrays with excellent wettability surface, we prepared ZnO-FeS2-CuI p-i-n photodiode by all-solution processed method with the high rectifying ratio of 197 at 1?V. Under AM 1.5 condition, the Jsc of 0.5?mA/cm(2), on-off current ratio of 371 and fast photoresponse at zero bias voltage were obtained. This good performance comes from excellent collection ability of photogenerated electrons and holes due to the increased depletion layer width for p-i-n structure. Finally, the high responsivity around 900?nm shows the potential as near infrared photodetectors applications. PMID:26077658

  13. Gamma Ray Array Detector Trigger Sub-System

    E-print Network

    Zhong-Wei, Du; Yi, Qian; KongJie,

    2012-01-01

    Gamma Ray Array Detector (GRAD) is one of External Target Facility (ETF) subsystems at the Heavy Ion Research Facility at Lanzhou. The trigger subsystem of the GRAD has been developed based on Field Programmable Gate Array (FPGAs) and PXI interface. The GRAD trigger subsystem makes prompt L1 trigger decisions to select valid events. These decisions are made by processing the hit signals from 1024 CsI scintillators of the GRAD. According to the physical requirements, the GRAD trigger subsystem generates 12-bit trigger signals that are passed to the ETF global trigger system. In addition, the GRAD trigger subsystem generates trigger data that are packed and transmitted to the host computer via PXI bus for off-line analysis. The trigger processing is implemented in the front-end electronics and one FPGA of the trigger module. The logic of PXI transmission and reconfiguration is implemented in the other FPGA of the trigger module. The reliable and efficient performance in the Gamma-ray experiments demonstrates th...

  14. Demonstration of a passive, low-noise, millimeter-wave detector array for imaging

    NASA Astrophysics Data System (ADS)

    Wikner, David; Grossman, Erich

    2009-05-01

    The design of a millimeter-wave (MMW) camera is presented. The camera is meant to serve as a demonstration platform for a new 32-channel MMW detector array that requires no pre-amplification prior to detection. The Army Research Laboratory (ARL) and National Institute of Standards and Technology (NIST) have worked with the Defense Advanced Research Projects Agency and several contractors for four years to develop an affordable MMW detector array technology suitable for use in a large staring array. The camera described uses one particular embodiment of detector array that resulted from the program. This paper reviews the design of the MMW optics that will be used to form imagery with the linear array and the tradeoffs made in that design. Also presented are the results of laboratory tests of the detector array that were made at both ARL and NIST.

  15. Energy spectrum measured by the telescope array surface detector

    NASA Astrophysics Data System (ADS)

    Ivanov, Dmitri

    2012-05-01

    Two conflicting measurements of the ultra high energy cosmic ray (UHECR) flux have been reported by the Akeno Giant Air Shower Array (AGASA) and the High Resolution Fly's Eye (HiRes) experiments. HiRes observes a 5sigma suppression at E = 1019.75 eV, which is in agreement with the prediction of Greisen-Zatsepin-Kuz'min (GZK) theory. AGASA, in contrast, sees the flux extended well beyond E = 1020 eV with no visible break, suggesting that the flux is limited only by the rate at which the sources can produce the UHECR and not by interaction of energetic particles with the cosmic microwave background, thus challenging the relativistic invariance principle. In response to this discrepancy, a new experiment named the Telescope Array (TA) has been deployed, which combines the detection elements used separately by HiRes and AGASA. We describe the TA surface detector (SD) analysis using a technique new to the field, which consists of a detailed Monte-Carlo (MC) simulation of the SD response to the natural cosmic rays, validating the MC by comparing its distributions with the data, and calculation of the SD aperture from the MC. We will also describe our reconstruction procedure, based solely upon the data, and its application to both data and the MC. Finally, we will describe the energy spectrum resulting from this analysis, which is found to be in excellent agreement with the HiRes result, and as such, is the first confirmation of the GZK effect by a ground array of scintillation counters.

  16. Method of fabricating multiwavelength infrared focal plane array detector

    NASA Technical Reports Server (NTRS)

    Forrest, Stephen R. (Inventor); Olsen, Gregory H. (Inventor); Kim, Dong-Su (Inventor); Lange, Michael J. (Inventor)

    1996-01-01

    A multiwavelength local plane array infrared detector is included on a common substrate having formed on its top face a plurality of In.sub.x Ga.sub.1-x As (x.ltoreq.0.53) absorption layers, between each pair of which a plurality of InAs.sub.y P.sub.1-y (y.ltoreq.1) buffer layers are formed having substantially increasing lattice parameters, respectively, relative to said substrate, for preventing lattice mismatch dislocations from propagating through successive ones of the absorption layers of decreasing bandgap relative to said substrate, whereby a plurality of detectors for detecting different wavelengths of light for a given pixel are provided by removing material above given areas of successive ones of the absorption layers, which areas are doped to form a pn junction with the surrounding unexposed portions of associated absorption layers, respectively, with metal contacts being formed on a portion of each of the exposed areas, and on the bottom of the substrate for facilitating electrical connections thereto.

  17. Motion artifacts from an inverse-geometry CT system with multiple detector arrays

    Microsoft Academic Search

    Samuel Mazin; Norbert Pelc

    2006-01-01

    Inverse-geometry CT (IGCT) is a promising new scanning geometry. Employing a scanned-anode x-ray source array the system is expected to provide sub-second volumetric imaging with isotropic resolution and no conebeam effects. Three detector arrays spaced apart laterally can achieve a 50 cm in-plane FOV with a 31 cm source. However, when three separate detector arrays are used, motion artifacts are

  18. A Low-Cost 128 128 Uncooled Infrared Detector Array in CMOS Process

    Microsoft Academic Search

    Selim Eminoglu; Mahmud Yusuf Tanrikulu; Tayfun Akin

    2008-01-01

    This paper discusses the implementation of a low-cost 128 times 128 uncooled infrared microbolometer detector array together with its integrated readout circuit (ROC) using a standard 0.35 mum n-well CMOS and post-CMOS MEMS processes. The detector array can be created with simple bulk-micromachining processes after the CMOS fabrication, without the need for any complicated lithography or deposition steps. The array

  19. Cerenkov radiators for photodiodes

    SciTech Connect

    Toevs, J.W.; Young, C.S.; Zagarino, P.A.; Seno, R.D.

    1982-01-01

    Several materials have been examined for use as Cerenkov converters in front of photodiodes in an effort to find a gamma detector system that has more sensitivity than a Compton detector but makes little sacrifice in bandwidth. Suprasil (fused silica) and UVT Lucite (acrylic) were 10-100 times more sensitive than a Compton detector and provided almost the same bandwidth. Barium fluoride provided almost 1000 times the sensitivity, but with a factor of 3 or 4 reduction in bandwidth. Relative sensitivities are strongly dependent on beam composition; the Cerenkov package is less sensitive to a pure ..gamma..-ray beam than to a ..gamma..-electron shower beam. Hence, beam composition must be considered in any application of these detectors.

  20. Performance of the First Detector Station for SEASA the Stockholm Educational Air Shower Array

    E-print Network

    Haviland, David

    Performance of the First Detector Station for SEASA the Stockholm Educational Air Shower Array ray air shower particles. Each station consists of three plastic scintillator detectors and employs to reconstruct the angle of incidence of the air showers. The timing resolution and detector separations

  1. Instrumentation Assembly, Characterization and Deployment of the Multichroic Detector Array for ACTPol

    NASA Astrophysics Data System (ADS)

    Ho, Shuay-Pwu; ACTPol Collaboration

    2015-04-01

    The Atacama Cosmology Telescope Polarimeter (ACTPol) is a polarization sensitive receiver for the 6 m Atacama Cosmology Telescope. ACTPol will make measurements of the small angular scale polarization anisotropies in the Cosmic Microwave Background (CMB). The deployment of the detector arrays for the receiver was fully completed in January, 2015. The entire focal plane is composed of three detector arrays, containing over 3000 transition edge sensors (TES) in total. The first two detector arrays, observing at 146 GHz were deployed in 2013 and 2014 respectively. The third and final array is designed to be multichroic, sensitive to both 90 GHz and 150 GHz, enabling increased sensitivity for observations of the CMB. In this talk I will focus on the laboratory assembly and characterization of the final detector array as well as its current status of deployment.

  2. Nova photodiode cooling undergraduate Research

    NASA Astrophysics Data System (ADS)

    Meyer, Benjamin

    2010-01-01

    Nova, an experiment that will study oscillation of neutrinos and ordering of neutrino masses, consists of a 200-ton detector on the Fermilab site (near detector) and a 14,000 ton detector in Northern Minnesota (far detector). These detectors require a massive amount of photodetectors (12,500 in all), called Hamamatsu Avalanche Photodiodes (APDs). These APDs require a stable temperature of -15C. I will describe tests of heat sink and thermoelectric cooler (TEC) designs (taken at Indiana University) to meet specifications for the APDs. These tests were done as a student in an REU (Research Experience for Undergraduates) during the summer of 2009.

  3. A Prototype Three-Dimensional Position Sensitive CdZnTe Detector Array

    SciTech Connect

    Zhang, Feng; He, Zhong; Seifert, Carolyn E.

    2007-08-01

    A new CdZnTe gamma-ray spectrometer system that employs two layers of modular detector arrays is being developed under the collaboration between the University of Michigan and the Pacific Northwest National Labaratory (PNNL). Each layer can accommodate up to three by three 3-dimensional position sensitive CdZnTe gamma-ray spectrometers. This array system is based on the newly developed VAS_UM/TAT4 ASIC readout electronics. Each of the nine detector modules consists of a pixellated CdZnTe detector and a VAS_UM/TAT4 ASIC frontend board. Each 1.51.51.0 cm3 CdZnTe detector employs an array of 11 by 11 pixellated anodes and a planar cathode. The energy depositions and 3-dimensional positions of individual interactions of each incident gamma ray can be obtained from pulse amplitude, location of each pixel anode and the drift time of electrons. Ten detectors were tested individually and half of them achieved resolution of <1.0% FWHM at 662 keV for single-pixel events (~30% of all 662 keV full energy deposition events). Two of them were tested in a simple array to verify that the upgrade to an array system does not sacrifice the performance of individual detectors. Experimental results of individual detectors and a twodetector array system are presented, and possible causes for several worse performing detectors are discussed.

  4. Focal plane arrays: Technology and applications; Proceedings of the Meeting, Cannes, France, Nov. 19, 20, 1987

    SciTech Connect

    Chatard, J.P.

    1988-01-01

    Focal plane array (FPA) technology is reviewed, and astrophysical and space applications of FPAs are described. Particular papers are presented on a CCD for SWIR photodiode multiplexing, the performance of a thermal imager using a hybrid pyroelectric detector array with MOSFET readout, a near-IR focal FPA for the Infrared Space Observatory camera (ISOCAM), FPAs for the ISOPHOT experiment, and performance measurements on a 32x32 InSb charge inspection device detector array for astronomical observations.

  5. Progress of Multicolor Single Detector to Detector Array Development for Remote Sensing

    NASA Technical Reports Server (NTRS)

    Abedin, M. Nurul; Refaat, Tamer F.; Bhat, Ishwara; Xiao, Ye-Gao; Bandra, Sumith; Gunapala, Sarath D.

    2004-01-01

    Knowledge of the spatial and temporal distribution of atmospheric species such as CO2, O3, H2O, and CH4 is important for understanding the chemistry and physical cycles involving Earth s atmosphere. Although several remote sensing techniques are suitable for such measurements they are considered high cost techniques involving complicated instrumentation. Therefore, simultaneous measurement of atmospheric species using a single remote sensing instrument is significant for minimizing cost, size and complexity. While maintaining the instrument sensitivity and range, quality of multicolor detector, in terms of high quantum efficiency and low noise are vital for these missions. As the first step for developing multicolor focal plan array, the structure of a single element multicolor detector is presented in this paper. The detector consists of three p-n junction layers of Si, GaSb and InAs wafer bonded to cover the spectral range UV to 900 nm, 800 nm to 1.7 m, and 1.5 m to 3.4 m, respectively. Modeling of the absorption coefficient for each material was carried out for optimizing the layers thicknesses for maximum absorption. The resulted quantum efficiency of each layer has been determined except InAs layer. The optical and electrical characterization of each layer structure is reported including dark current and spectral response measurements of Si pin structure and of GaSb and InAs p-n junctions. The effect of the material processing is discussed.

  6. Delta-Doped CCDs as Detector Arrays in Mass Spectrometers

    NASA Technical Reports Server (NTRS)

    Nikzad, Shouleh; Jones, Todd; Jewell, April; Sinha, Mahadeva

    2007-01-01

    In a conventional mass spectrometer, charged particles (ions) are dispersed through a magnetic sector onto an MCP at an output (focal) plane. In the MCP, the impinging charged particles excite electron cascades that afford signal gain. Electrons leaving the MCP can be read out by any of a variety of means; most commonly, they are post-accelerated onto a solid-state detector array, wherein the electron pulses are converted to photons, which, in turn, are converted to measurable electric-current pulses by photodetectors. Each step in the conversion from the impinging charged particles to the output 26 NASA Tech Briefs, February 2007 current pulses reduces spatial resolution and increases noise, thereby reducing the overall sensitivity and performance of the mass spectrometer. Hence, it would be preferable to make a direct measurement of the spatial distribution of charged particles impinging on the focal plane. The utility of delta-doped CCDs as detectors of charged particles was reported in two articles in NASA Tech Briefs, Vol. 22, No. 7 (July 1998): "Delta-Doped CCDs as Low-Energy-Particle Detectors" (NPO-20178) on page 48 and "Delta- Doped CCDs for Measuring Energies of Positive Ions" (NPO-20253) on page 50. In the present developmental miniature mass spectrometers, the above mentioned miniaturization and performance advantages contributed by the use of delta-doped CCDs are combined with the advantages afforded by the Mattauch-Herzog design. The Mattauch- Herzog design is a double-focusing spectrometer design involving an electric and a magnetic sector, where the ions of different masses are spatially separated along the focal plane of magnetic sector. A delta-doped CCD at the focal plane measures the signals of all the charged-particle species simultaneously at high sensitivity and high resolution, thereby nearly instantaneously providing a complete, high-quality mass spectrum. The simultaneous nature of the measurement of ions stands in contrast to that of a scanning mass spectrometer, in which abundances of different masses are measured at successive times.

  7. The development and test of ultra-large-format multi-anode microchannel array detector systems

    NASA Technical Reports Server (NTRS)

    Timothy, J. G.

    1984-01-01

    The specific tasks that were accomplished with each of the key elements of the multi-anode microchannel array detector system are described. The modes of operation of position-sensitive electronic readout systems for use with high-gain microchannel plates are described and their performance characteristics compared and contrasted. Multi-anode microchannel array detector systems with formats as large as 256 x 1024 pixels are currently under evaluation. Preliminary performance data for sealed ultraviolet and visible-light detector tubes show that the detector systems have unique characteristics which make them complementary to photoconductive array detectors, such as CCDs, and superior to alternative pulse-counting detector systems employing high-gain MCPs.

  8. Infrared detectors and focal plane arrays; Proceedings of the Meeting, Orlando, FL, Apr. 18, 19, 1990

    NASA Astrophysics Data System (ADS)

    Dereniak, Eustace L.; Sampson, Robert E.

    1990-09-01

    The papers contained in this volume provide an overview of recent advances and the current state of developments in the field of infrared detectors and focal plane arrays. Topics discussed include nickel silicide Schottky-barrier detectors for short-wavelength infrared applications; high performance PtSi linear and focal plane arrays; and multispectral band Schottky-barrier IRSSD for remote-sensing applications. Papers are also presented on the performance of an Insi hybrid focal array; characterization of IR focal plane test stations; GaAs CCD readout for engineered bandgap detectors; and fire detection system for aircraft cargo bays.

  9. Ultrasound-assisted solid-phase extraction coupled with photodiode-array and fluorescence detection for chemotaxonomy of isoflavone phytoestrogens in Trifolium L. (Clover) species.

    PubMed

    Zg髍ka, Grazyna

    2009-04-01

    Detailed chemotaxonomic studies were undertaken to establish the qualitative profile and real amounts of the pharmacologically active isoflavone aglycones genistein, daidzein, formononetin, and biochanin A in aerial parts of thirteen Trifolium L. (clover) species, native to Poland. A newly elaborated micropreparative technique--SPE--on BakerBond octadecyl, cyclohexyl, and phenyl cartridges was used in combination with ultrasound-assisted extraction for isolation of isoflavone aglycones from hydrolyzed samples. The effectiveness of all three SPE sorbents in the purification of plant extracts was compared and very high recoveries (>96%) were documented for four isoflavones. Classical photodiode-array and very sensitive fluorescence detection, coupled with reversed-phase high-performance liquid chromatography (RP-HPLC), were employed to obtain the most reliable qualitative and quantitative results. Chemotaxonomic differences combined with flower color variability were demonstrated within thirteen clover species. Concentration levels of particular isoflavones in ten Trifolium species possessing flowers with white, pink, or purple-red corolla ranged from approximately 3 to approximately 3300 microg/g dry weight, while in three yellow flowering clovers (T. aureum, T. dubium, and T. campestre) isoflavone compounds have not been detected at all. RSD values, determined for intra- and inter-day precision of the quantitative results, were not higher than 6.2% and 7.1%, respectively. PMID:19226567

  10. Identification and analysis of alkaloids in cortex Phellodendron amurense by high-performance liquid chromatography with electrospray ionization mass spectrometry coupled with photodiode array detection.

    PubMed

    Xian, Xiaoyan; Sun, Bohang; Ye, Xueting; Zhang, Guanying; Hou, Pengyi; Gao, Huiyuan

    2014-07-01

    Alkaloids from Cortex Phellodendron amurense Rupr. were identified to determine the material basis for the bioactivity of this herb. HPLC-ESI-MS with photodiode array detection coupled to XCharge C18 column was applied to analyze the alkaloids qualitatively and quantitatively. A total of 37 alkaloids were identified and tentatively characterized from the ethanol extract by online ESI-MS(n) fragmentation and UV spectral analysis. A total of ten alkaloids, including four novel natural products, were tentatively identified for the first time in P. amurense. The fragmentation pathways for certain compounds were analyzed. The contents of a pair of isomers (columbamine and jatrorrhizine) and four main alkaloids (phellodendrine, magnoflorine, berberine, and palmatine) were simultaneously quantified using the aforementioned method. Results showed that the newly discovered and known components of P. amurense were helpful in determining the material basis for the bioactivity of the herb. The application of the XCharge C18 column is a suitable and practical method for the isolation of alkaloids in plants. PMID:24723373

  11. Determination of polymer additives-antioxidants and ultraviolet (UV) absorbers by high-performance liquid chromatography coupled with UV photodiode array detection in food simulants.

    PubMed

    Gao, Yali; Gu, Yanxiang; Wei, Yun

    2011-12-28

    An analytical method for the quantitative determination of migration levels of polymer additives such as antioxidants and UV absorbers in food packages by high-performance liquid chromatography coupled with UV-vis photodiode array detection has been developed. The pretreatment step involved solid-phase extraction with silica C18 cartridges. The analytical method showed good linearity, presenting regression coefficients (R(2)) ? 0.9990 for all compounds. This optimized method was also validated with respect to precision, reproducibility, stability, and accuracy. The limits of detection and quantification were between 0.09 and 1.72 ?g mL(-1) and between 0.20 and 5.64 ?g mL(-1) for 12 analytes, respectively. Recoveries were in the range of 67.48 and 108.55%, with relative standard deviations between 2.76 and 9.81%. Migration levels of antioxidants and UV absorbers were determined. Butylated hydroxyanisole, 2,6-di-tert-butyl-4-methylphenol (BHT), 2,4-di-tert-butylphenol, Cyanox 2246, Irganox 1035, Tinuvin 326, Tinuvin 328, Irganox 1010, and Irganox 1330 were detected; BHT and Cyanox 2246 were at higher levels than the specific migration levels in some food simulants. PMID:22141443

  12. Use of single photon counting detector arrays in combined PET/MR: Characterization of LYSO-SiPM detector modules and comparison with a LSO-APD detector

    NASA Astrophysics Data System (ADS)

    Spanoudaki, V. C.; Mann, A. B.; Otte, A. N.; Konorov, I.; Torres-Espallardo, I.; Paul, S.; Ziegler, S. I.

    2007-12-01

    We propose in this study a novel PET detector concept as insert for simultaneous PET/MR imaging, using arrays of Silicon Photomultipliers (SiPMs) as photodetectors, read out by a data acquisition system based on sampling ADCs. A 2 2 LSO-SiPM detector array and four single channel LYSO-SiPM detectors have been evaluated and compared to a LSO-APD detector. A 17.9% energy resolution and a 1.4 ns time resolution have been measured. No degradation of these values could be detected when simultaneous MR acquisitions were performed. The non-linear detector behaviour due to the limited dynamic range and recovery time effects has been studied. In addition, the contribution of dark counts and optical crosstalk for PET applications was also addressed. The feasibility for position localization of the incident light to a SiPM array using Anger logic has been investigated.

  13. Photodiode-Coupled Light Modulator

    NASA Technical Reports Server (NTRS)

    Maserjian, Joseph; Eng, Sverre T.

    1989-01-01

    Absorption of one light beam controls transmission of another. High-performance monolithic light modulator comprised of p-doped/intrinsic/n-doped (PIN) GaAs photodiode grown directly over InAs/GaAs PIN multiple-quantum-well (MQW) diode. Photodiode-coupled multiple-quantum-well modulator includes advanced semi-conductor microstructures enhancing electro-optical properties. Using standard lithographic and etching techniques for defining picture elements, structures fabricated into two-dimensional arrays for use as spatial light modulators.

  14. Monte Carlo simulation of the standardization of 22Na using scintillation detector arrays.

    PubMed

    Sato, Y; Murayama, H; Yamada, T; Hasegawa, T; Oda, K; Unno, Y; Yunoki, A

    2010-01-01

    In order to calibrate PET devices by a sealed point source, we contrived an absolute activity measurement method for the sealed point source using scintillation detector arrays. This new method was verified by EGS5 Monte Carlo simulation. PMID:20083411

  15. Method of fabricating a PbS-PbSe IR detector array

    NASA Technical Reports Server (NTRS)

    Barrett, John R. (Inventor)

    1987-01-01

    A silicon wafer is provided which does not employ individually bonded leads between the IR sensitive elements and the input stages of multiplexers. The wafer is first coated with lead selenide in a first detector array area and is thereafter coated with lead sulfide within a second detector array area. The described steps result in the direct chemical deposition of lead selenide and lead sulfide upon the silicon wafer to eliminate individual wire bonding, bumping, flip chiping, planar interconnecting methods of connecting detector array elements to silicon chip circuitry, e.g., multiplexers, to enable easy fabrication of very long arrays. The electrode structure employed, produces an increase in the electrical field gradient between the electrodes for a given volume of detector material, relative to conventional electrode configurations.

  16. Evaluation of selected detector arrays for space applications

    NASA Technical Reports Server (NTRS)

    Lowrance, J. L.

    1986-01-01

    The development of a high density Schottky barrier Infrared Charged Coupled Device (IRCCD) type image sensor for earth observation was initiated. A dual band 512 pixel linear array was developed, which was capable of being butted end to end to make an arbitrarily long linear array. Measurement made on palladium silicide IRCCDs that were two-dimensional 63 x 32 pixel arrays were summarized. The test data on a 512 pixel linear array is also summarized.

  17. Characterization of small CdTe detectors to be used for linear and matrix arrays

    Microsoft Academic Search

    F. Casali; D. Bollini; P. Chirco; M. Rossi; G. Baldazzi; W. Dusi; E. Caroli; G. Di Cocco; A. Donati; G. Landini; J. B. Stephen

    1992-01-01

    The authors describe a comparison performed between two types of CdTe detectors operating in different configurations, considering the possibility of constructing array detectors for medical and industrial applications, and the development of a multi-probe matrix array for use in astrophysics, such as for the detection of 511-keV annihilation radiation. The main interest was in the development and optimization of small

  18. Read-Noise Characterization of Focal Plane Array Detectors via Mean-Variance Analysis

    SciTech Connect

    Sperline, Roger P.; Knight, Andrew K.; Gresham, Christopher A.; Koppenaal, David W.; Hieftje, Gary M.; Denton, M Bonner B.

    2005-11-01

    Mean-variance analysis is described as a method for characterization of the read-noise and gain of Focal Plane Array (FPA) detectors, including CCDs, CIDs, and CMOS multiplexers (IR arrays). Practical FPA detector characterization is outlined. The non-destructive readout capability available in some FPA devices is discussed as a means for signal-to-noise ratio improvement. Derivations of the equations are fully presented to unify understanding of this method by the spectroscopic community.

  19. Studies on the fabrication method for the array of polycrystalline mercuric iodide detectors

    NASA Astrophysics Data System (ADS)

    Zheng, Wei-feng; Shi, Wei-min; Li, Dong-mei; Qin, Juan; Wang, Lin-jun; Huang, Jian; Yu, Jun-yang; Xia, Yi-ben

    2009-07-01

    The Mercuric Iodide (HgI2) semiconductor array detectors possess the characters of low noise, high detection efficiency, high energy resolution and working in room temperature. In this work, modified hot-wall physical vapor deposition (HW-PVD) method was used to grow high-quality polycrystalline HgI2 thin-films on ITO glasses, and then 44 and 88 HgI2 array detectors for X-ray radiation were fabricated. We used two fabrication processes for polycrystalline HgI2 array detectors. One was using mask made of stainless steel with good flexibility; while the other was to photo lithography the array on the ITO glass. The main purpose for this work was to compare the electrical properties of polycrystalline HgI2 array detectors fabricated from different processes, and to find out the optimal process for HgI2 detectors. Results indicated that the photo lithography method was a better way to fabricate polycrystalline mercuric iodide array detector than using mask method.

  20. Development of a Gamma-ray Burst Detector Based on the Silicon Drift Detector Array and Scintillators

    SciTech Connect

    Yamaoka, Kazutaka; Arai, Yusuke; Doshida, Takaaki; Watanabe, Tsuyoshi; Tsutsui, Akihito; Asano, Satoshi; Yoshida, Kotaro; Yoshida, Atsumasa [Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara, Kanagawa 229-8558 (Japan); Pahlke, Andreas [KETEK GmbH, Hofer Strasse 3, 81737 Munchen (Germany); Ikeda, Hirokazu; Takahashi, Tadayuki [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (ISAS/JAXA), 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan); Mori, Kunishiro [Clear Pulse Ltd, 6-25-17 Chuoh, Ohta-ku, Tokyo 143-0024 (Japan); Kato, Hiroshi [Makishima Cosmic Radiation Laboratory, Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

    2008-05-22

    We propose a gamma-ray burst (GRB) detector combining the silicon drift detector (SDD) array and scintillators with broadband X-ray and gamma-ray coverage (0.5-1000 keV or more), high energy resolution (2-10%) and high time resolution ({approx}{mu}s) in space. To realize such compact high-performance detector without photomultiplier tubes, we constructed proto-type model using KETEK SDD with a detection area of 1 cm{sup 2} and BGO crystal. The detector shows a very good performance. Obtained FWHM energy resolution was 191 eV at 5.9 keV in the SDD, while 6.5 % at 662 keV in the BGO at -30 deg. C. Evaluation of the 7 channel SDD array and development of analog ASIC for its readout are also presented.

  1. Signal to Noise Ratio of APD-Based Monolithic Scintillator Detectors for High Resolution PET

    Microsoft Academic Search

    Marnix C. Maas; Dennis R. Schaart; Herman T. van Dam; Jan Huizenga; J. C. Brouwer; Peter Bruyndonckx; Cedric Lemaitre; Carel W. E. van Eijk

    2008-01-01

    Monolithic scintillator detectors, consisting of several cm3 of scintillating material coupled to one or more Hamamatsu S8550 avalanche photodiode (APD) arrays, are proposed as detectors for high resolution positron emission tomography (PET). In this work, the factors contributing to the variance on the signals are investigated, and their effects on the energy, time and spatial resolutions are analyzed. Good agreement

  2. A Near-Infrared 64-pixel Superconducting Nanowire Single Photon Detector Array with Integrated Multiplexed Readout

    E-print Network

    Allman, M S; Stevens, M; Gerrits, T; Horansky, R D; Lita, A E; Marsili, F; Beyer, A; Shaw, M D; Kumor, D; Mirin, R; Nam, S W

    2015-01-01

    We demonstrate a 64-pixel free-space-coupled array of superconducting nanowire single photon detectors optimized for high detection efficiency in the near-infrared range. An integrated, readily scalable, multiplexed readout scheme is employed to reduce the number of readout lines to 16. The cryogenic, optical, and electronic packaging to read out the array, as well as characterization measurements are discussed.

  3. A near-infrared 64-pixel superconducting nanowire single photon detector array with integrated multiplexed readout

    NASA Astrophysics Data System (ADS)

    Allman, M. S.; Verma, V. B.; Stevens, M.; Gerrits, T.; Horansky, R. D.; Lita, A. E.; Marsili, F.; Beyer, A.; Shaw, M. D.; Kumor, D.; Mirin, R.; Nam, S. W.

    2015-05-01

    We demonstrate a 64-pixel free-space-coupled array of superconducting nanowire single photon detectors optimized for high detection efficiency in the near-infrared range. An integrated, readily scalable, multiplexed readout scheme is employed to reduce the number of readout lines to 16. The cryogenic, optical, and electronic packaging to read out the array as well as characterization measurements are discussed.

  4. Modulation Transfer Function (MTF) measurement techniques for lenses and linear detector arrays

    NASA Technical Reports Server (NTRS)

    Schnabel, J. J., Jr.; Kaishoven, J. E., Jr.; Tom, D.

    1984-01-01

    Application is the determination of the Modulation Transfer Function (MTF) for linear detector arrays. A system set up requires knowledge of the MTF of the imaging lens. Procedure for this measurement is described for standard optical lab equipment. Given this information, various possible approaches to MTF measurement for linear arrays is described. The knife edge method is then described in detail.

  5. Observation of high energy atmospheric neutrinos with the Antarctic muon and neutrino detector array

    Microsoft Academic Search

    J. Ahrens; E. Andr閟; X. Bai; G. Barouch; S. W. Barwick; R. C. Bay; T. Becka; K.-H. Becker; D. Bertrand; F. Binon; A. Biron; J. Booth; O. Botner; A. Bouchta; O. Bouhali; M. M. Boyce; S. Carius; A. Chen; D. Chirkin; J. Conrad; J. Cooley; C. G. S. Costa; D. F. Cowen; E. Dalberg; C. de Clercq; T. De Young; P. Desiati; J.-P. Dewulf; P. Doksus; J. Edsj; P. Ekstr鰉; T. Feser; J.-M. Fr鑢e; T. K. Gaisser; M. Gaug; A. Goldschmidt; A. Hallgren; F. Halzen; K. Hanson; R. Hardtke; T. Hauschildt; M. Hellwig; H. Heukenkamp; G. C. Hill; P. O. Hulth; S. Hundertmark; J. Jacobsen; A. Karle; J. Kim; B. Koci; L. K鰌ke; M. Kowalski; J. I. Lamoureux; H. Leich; M. Leuthold; P. Lindahl; I. Liubarsky; P. Loaiza; D. M. Lowder; J. Madsen; P. Marciniewski; H. S. Matis; C. P. McParland; T. C. Miller; Y. Minaeva; P. Miocinovic; P. C. Mock; R. Morse; T. Neunh鰂fer; P. Niessen; D. R. Nygren; H. 謌elman; Ph. Olbrechts; C. P閞ez de Los Heros; A. C. Pohl; R. Porrata; P. B. Price; G. T. Przybylski; K. Rawlins; C. Reed; W. Rhode; M. Ribordy; S. Richter; J. Rodr韌uez Martino; P. Romenesko; D. Ross; H.-G. Sander; T. Schmidt; D. Schneider; R. Schwarz; A. Silvestri; M. Solarz; G. M. Spiczak; C. Spiering; N. Starinsky; D. Steele; P. Steffen; R. G. Stokstad; O. Streicher; P. Sudhoff; K.-H. Sulanke; I. Taboada; L. Thollander; T. Thon; S. Tilav; M. Vander Donckt; C. Walck; C. Weinheimer; C. H. Wiebusch; C. Wiedeman; R. Wischnewski; H. Wissing; K. Woschnagg; W. Wu; G. Yodh; S. Young

    2002-01-01

    The Antarctic muon and neutrino detector array (AMANDA) began collecting data with ten strings in 1997. Results from the first year of operation are presented. Neutrinos coming through the Earth from the Northern Hemisphere are identified by secondary muons moving upward through the array. Cosmic rays in the atmosphere generate a background of downward moving muons, which are about 106

  6. The FPGA Pixel Array Detector Marianne S. Hromalik a,b,n

    E-print Network

    Gruner, Sol M.

    The FPGA Pixel Array Detector Marianne S. Hromalik a,b,n , Katherine S. Green b , Hugh T. Philipp b field programmable gate array (FPGA) into a 3-layer device along with a high-resistivity diode detection an energy-discriminating photon-counting front end with photon hits streamed directly to the FPGA via

  7. Radiated power accounting and impurity transport estimates at the CDX-U spherical torus using photodiode arrays and FUV spectroscopy.

    NASA Astrophysics Data System (ADS)

    Soukhanovskii, V. A.; Stutman, D.; Iovea, M.; Finkenthal, M.; Moos, H. W.; Hoffman, D.; Munsat, T.; Menard, J.; Majeski, R.; Kaita, R.; Jones, B.; Spaleta, J.; Taylor, G.; Efthimion, P.

    1999-11-01

    The recently installed tangentially viewing ten channel fast AXUV diode array, together with poloidally viewing spectrally filtered SXR arrays, the XUV, FUV, visible spectrometers and the fast filtered CCD camera are used for radiated power measurements and intrinsic impurity transport estimates at the CDX-U spherical torus, in plasmas with tens of kA current and temperature in sub-hundred eV range. The inferred carbon, oxygen and hydrogen emissivity profiles and measured Te and ne profiles are used as inputs for impurity transport and collisional-radiative models. Bolometric corrections are derived to account for non-linearity of the AXUV diode spectral response to lower energy photons. The impact of charge exchange between impurity ions and neutrals on impurity transport and radiated power is investigated. The temperature diagnostics potential of the CIV/CV spectral line ratio is discussed and comparisons to the Thomson scattering and EBW measurements are made. This work is supported by U.S. DoE Grant DE-FG02-86ER53214 at JHU and DoE Contract No. DE-AC02-76-CHO-3073 at PPPL.

  8. Stable, high quantum efficiency silicon photodiodes for vacuum-UV applications

    NASA Astrophysics Data System (ADS)

    Korde, Raj; Canfield, L. Randall; Wallis, Brad

    1988-01-01

    Silicon photodiodes have been developed by defect-free phosphorus diffusion having practically no carrier recombination at the SiSiO2 interface or in the front diffused region. The quantum efficiency of these photodiodes was found to be around 120 percent at 100 nm. Unlike the previously tested silicon photodiodes, the developed photodiodes exhibit extremely stable quantum efficiency over extended periods of time. The possibility of using these photodiodes as vacuum ultraviolet detector standards is being currently investigated.

  9. A PCI Based Data Acquisition System for Ground Array Detectors with Wireless Synchronization through GPS

    Microsoft Academic Search

    P. Assis; P. Brogueira; L. Melo; M. Pimenta; J. C. Silva; J. Varela

    2003-01-01

    The synchronization of ground based cosmic ray detectors is a recurring problem. Traditional acquisition systems usually drive signal cables from each station of an array of detectors to a central acquisition system. In the context of ULTRA, a support experiment for the EUSO mission, a distributed wireless acquisition system based on a PCI board with synchronization through GPS was developed.

  10. 2D Array of Far-infrared Thermal Detectors: Noise Measurements and Processing Issues

    NASA Technical Reports Server (NTRS)

    Lakew, B.; Aslam, S.; Stevenson, T.

    2008-01-01

    A magnesium diboride (MgB2) detector 2D array for use in future space-based spectrometers is being developed at GSFC. Expected pixel sensitivities and comparison to current state-of-the-art infrared (IR) detectors will be discussed.

  11. Photoelectric array detectors for use at XUV wavelengths. [for Spacelab solar-physics facilities

    NASA Technical Reports Server (NTRS)

    Timothy, J. G.

    1981-01-01

    The characteristics of photoelectric detector systems for use at visible-light, ultraviolet, and X-ray wavelengths are briefly reviewed in the context of the needs of the Spacelab solar-physics facilities. Photoelectric array detectors for use at XUV wavelengths between 90 and 1500 A are described, and their use in the ESA Grazing-Incidence Solar Telescope (GRIST) facility is discussed.

  12. Chemical imaging of cotton fibers using an infrared microscope and a focal-plane array detector

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this presentation, the chemical imaging of cotton fibers with an infrared microscope and a Focal-Plane Array (FPA) detector will be discussed. Infrared spectroscopy can provide us with information on the structure and quality of cotton fibers. In addition, FPA detectors allow for simultaneous spe...

  13. Study and Testing of a Pixel Array Detector for Electron Microscope Application

    E-print Network

    Gardel, Margaret

    Study and Testing of a Pixel Array Detector for Electron Microscope Application Thomas A Caswell to the detectors and the electron microscopes. Adapting the PAD for us in an electron microscope is a project of the experimental work the microscope was operated by Peter Ercius. He was also instrumental in my introduction

  14. Development of a dark matter detector using series arrays of superconducting tunnel junctions

    Microsoft Academic Search

    E. Esposito; L. Angrave; N. E. Booth; R. J. Gaitskell; T. J. Giles; C. H鰏s; E. P. Houwman; M. J. J. van den Putte; G. L. Salmon; S. W鋘ninger

    1996-01-01

    We are developing a dark matter detector for Weakly Interacting Massive Particles (WIMPs) using Series Arrays of Superconducting Tunnel Junctions (SASTJs) to read out phonon signals from absorber crystals. We discuss the factors which have determined the choice of our detector scheme. As an improvement over previously produced SASTJs using a shadow mask technique, a new fabrication process of high-quality

  15. Potential for SPECT cameras utilizing photodiode readout of scintillator crystals

    SciTech Connect

    Moses, W.W.; Derenzo, S.E.; Gruber, G.J.; Huesman, R.H. [Lawrence Berkeley Lab., CA (United States)] [and others

    1997-05-01

    We present a conceptual design for a SPECT detector consisting of an array of 3x3x5 mm CsI(Tl) scintillator crystals individually read out by an array of 3 mm square silicon photodiodes. The interaction position is not determined by Anger logic, but by the location of the individual crystal/photodiode element in which the gamma ray is observed. Since the design is modular (each module typically having 64 crystals, photodiodes, and charge amplifiers, and one multiplexer circuit to reduce the number of readout channels), a large variety of camera geometries can be realized. Advantages of this design over conventional cameras (NaI(Tl) scintillator/photomultiplier tube) are lower gain drift (i.e. higher stability), smaller size, significantly higher count rate capability, and potentially lower cost. For the 141 keV emissions of Tc-99m, both CsI(Tl) and NaI(Tl) have 85-90% photoelectric fraction, but CsI(TI) has an attenuation length of 3.0 mm as compared to 4.5 mm for NaI(Tl). Thus, a 5 mm thick CsI(Tl) camera has singular efficiency to a Nal(Tl) camera with a 7.5 mm thickness (between 1/4 and 3/8 inch). The light output of CsI(Tl) is 25% higher than that of Nal(Tl), and while its 565 nm emissions are not efficiently detected with photomultiplier tubes, they are well matched to photodiode detection.

  16. Simultaneous determination of thirteen beta-blockers and one metabolite by gradient high-performance liquid chromatography with photodiode-array UV detection.

    PubMed

    Delamoye, Magali; Duverneuil, Charlotte; Paraire, Fran鏾is; de Mazancourt, Philippe; Alvarez, Jean-Claude

    2004-04-20

    A new rapid and sensitive high-performance liquid chromatography (HPLC) method has been developed for the simultaneous identification and quantification in human plasma of the 13 most commonly prescribed beta-blockers and one active metabolite-atenolol, sotalol, diacetolol, carteolol, nadolol, pindolol, acebutolol, metoprolol, celiprolol, oxprenolol, labetalol, propranolol, tertatolol and betaxolol. It involves liquid-liquid extraction procedures followed by liquid chromatography coupled to photodiode-array UV detection with a fixed wavelength at 220 nm for quantification. Compounds were separated on a 5 microm Hypurity C(18) (ThermoHypersil) analytical column (250 mm x 4.6 mm, i.d.) using a gradient of acetonitrile-phosphate buffer pH 3.8 at a flow rate of 1.0 ml/min. The total analysis time was 26 min per sample. Extraction recoveries were between 74 and 113% for the polar compounds and between 20 and 56% for the most apolar compounds. Calibration lines were linear in the range from 25 to 1000 ng/ml for all compounds excepted carteolol and nadolol (50-1000 ng/ml), all of them with coefficients of determination (r2 values) >/=0.994. Limits of detection (LODs) ranged from 5 to 10 ng/ml. Intra-assay and inter-assay precision and accuracy were studied at two concentration levels (100 and 500 ng/ml). The intra-assay coefficients of variation (CVs) for all compounds were

  17. Influence of nonpolar substances on the extraction efficiency of six alkaloids in Zoagumhwan investigated by ultra performance liquid chromatography and photodiode array detection.

    PubMed

    Zhao, Yanling; Jia, Lei; Yang, Hongbo; Wang, Jiabo; Zhang, Ping; Li, Ruisheng; Gong, Man; Luo, Shengqiang; Liu, Shijing; Xiao, Xiaohe

    2012-01-01

    A reverse phase ultra performance liquid chromatography and photodiode array (UPLC-PDA) detection method was established for the determination of six alkaloids in Zoagumhwan (ZGW), and further for investigating the influence of nonpolar substances on the extraction efficiency of these alkaloids. The method was based on a BEH C(18) (50 mm 2.1 mm, 1.7 ?m) column and mobile phase of aqueous phosphoric acid and acetonitrile including 0.05% buffer solution under gradient elution. ZGW samples of ZGW I, II, III and IV were obtained and prepared by pre-processing the crude materials of Coptidis rhizoma and Evodiae fructus using four technologies, namely direct water decoction, removal of nonpolar substances in Evodiae fructus by supercritical fluid extraction (SFE), removal of nonpolar substances in ZGW by SFE and removal of nonpolar substances in ZGW by steam distillation. The developed and validated UPLC-PDA method was precise, accurate and sensitive enough based on the facts that the six alkaloids showed good regression (r > 0.9998), the limit of detections and quantifications for six alkaloids were less than 28.8 and 94.5 ng/mL, respectively, and the recovery was in the range of 98.56%-103.24%. The sequence of the total contents of six alkaloids in these samples was ZGW II > ZGW IV > ZGW III > ZGW I. ZGW II, in which nonpolar substances, including essential oils, were firstly removed from Evodiae fructus by SFE, had the highest content of the total alkaloids, indicating that extraction efficiency of the total alkaloids could be remarkably increased after Evodiae fructus being extracted by SFE. PMID:23174900

  18. A 4 pi charged-particle detector array for light-ion-induced nuclear fragmentation studies

    Microsoft Academic Search

    K. Kwiatkowski; A. Alexander; D. S. Bracken; J. Brzychczyk; J. Dorsett; R. Ensman; E. Renshaw Foxford; K. Komisarcik; K. N. McDonald; K. B. Morley; J. Poehlman; C. Powell; V. E. Viola; N. R. Yoder; J. Ottarson; N. Madden

    1994-01-01

    Operating characteristics of the Indiana Silicon Sphere 4 pi detector array are outlined. The detector geometry is spherical, with 90 telescopes in the forward hemisphere and 72 at backward angles, covering a total solid angle of 74% of 4pi. Each telescope consists of a simple gas-ion chamber, operated with C3F8 gas, followed by a 0.5 mm thick ion-implanted silicon detector

  19. Investigation of depth-of-interaction by pulse shape discrimination in multicrystal detectors read out by avalanche photodiodes

    Microsoft Academic Search

    A. Saoudi; C. M. Pepin; F. Dion; M. Bentourkia; R. Lecomte; M. Andreaco; M. Casey; R. Nutt; H. Dautet

    1999-01-01

    The measurement of depth of interaction (DOI) within detectors is necessary to improve resolution uniformity across the FOV of small diameter PET scanners. DOI encoding by pulse shape discrimination (PSD) has definite advantages as it requires only one readout per pixel and it allows DOI measurement of photoelectric and Compton events. The PSD time characteristics of various scintillators were studied

  20. Integrated filter and detector array for spectral imaging

    NASA Technical Reports Server (NTRS)

    Labaw, Clayton C. (inventor)

    1992-01-01

    A spectral imaging system having an integrated filter and photodetector array is disclosed. The filter has narrow transmission bands which vary in frequency along the photodetector array. The frequency variation of the transmission bands is matched to, and aligned with, the frequency variation of a received spectral image. The filter is deposited directly on the photodetector array by a low temperature deposition process. By depositing the filter directly on the photodetector array, permanent alignment is achieved for all temperatures, spectral crosstalk is substantially eliminated, and a high signal to noise ratio is achieved.

  1. Trigger and aperture of the surface detector array of the Pierre Auger Observatory

    NASA Astrophysics Data System (ADS)

    Abraham, J.; Abreu, P.; Aglietta, M.; Ahn, E. J.; Allard, D.; Allekotte, I.; Allen, J.; Alvarez-Mu駃z, J.; Ambrosio, M.; Anchordoqui, L.; Andringa, S.; Anti?i?, T.; Anzalone, A.; Aramo, C.; Arganda, E.; Arisaka, K.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avila, G.; B鋍ker, T.; Badagnani, D.; Balzer, M.; Barber, K. B.; Barbosa, A. F.; Barroso, S. L. C.; Baughman, B.; Bauleo, P.; Beatty, J. J.; Becker, B. R.; Becker, K. H.; Bell閠oile, A.; Bellido, J. A.; Benzvi, S.; Berat, C.; Bergmann, T.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanch-Bigas, O.; Blanco, F.; Blanco, M.; Bleve, C.; Bl黰er, H.; Boh?ov, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brogueira, P.; Brown, W. C.; Bruijn, R.; Buchholz, P.; Bueno, A.; Burton, R. E.; Busca, N. G.; Caballero-Mora, K. S.; Caramete, L.; Caruso, R.; Castellina, A.; Catalano, O.; Cataldi, G.; Cazon, L.; Cester, R.; Chauvin, J.; Chiavassa, A.; Chinellato, J. A.; Chou, A.; Chudoba, J.; Clay, R. W.; Colombo, E.; Coluccia, M. R.; Concei玢o, R.; Contreras, F.; Cook, H.; Cooper, M. J.; Coppens, J.; Cordier, A.; Cotti, U.; Coutu, S.; Covault, C. E.; Creusot, A.; Criss, A.; Cronin, J.; Curutiu, A.; Dagoret-Campagne, S.; Dallier, R.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; de Domenico, M.; de Donato, C.; de Jong, S. J.; de La Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; de Mitri, I.; de Souza, V.; de Vries, K. D.; Decerprit, G.; Del Peral, L.; Deligny, O.; Della Selva, A.; Delle Fratte, C.; Dembinski, H.; di Giulio, C.; Diaz, J. C.; D韆z Castro, M. L.; Diep, P. N.; Dobrigkeit, C.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; Dos Anjos, J. C.; Dova, M. T.; D'Urso, D.; Dutan, I.; Duvernois, M. A.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferrero, A.; Fick, B.; Filevich, A.; Filip?i?, A.; Fleck, I.; Fliescher, S.; Fracchiolla, C. E.; Fraenkel, E. D.; Fr鰄lich, U.; Fulgione, W.; Gamarra, R. F.; Gambetta, S.; Garc韆, B.; Garc韆 G醡ez, D.; Garcia-Pinto, D.; Garrido, X.; Gelmini, G.; Gemmeke, H.; Ghia, P. L.; Giaccari, U.; Giller, M.; Glass, H.; Goggin, L. M.; Gold, M. S.; Golup, G.; Gomez Albarracin, F.; G髆ez Berisso, M.; Gon鏰lves, P.; Gonzalez, D.; Gonzalez, J. G.; G髍a, D.; Gorgi, A.; Gouffon, P.; Gozzini, S. R.; Grashorn, E.; Grebe, S.; Grigat, M.; Grillo, A. F.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Hague, J. D.; Halenka, V.; Hansen, P.; Harari, D.; Harmsma, S.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Herve, A. E.; Hojvat, C.; Holmes, V. C.; Homola, P.; H鰎andel, J. R.; Horneffer, A.; Hrabovsk, M.; Huege, T.; Hussain, M.; Iarlori, M.; Insolia, A.; Ionita, F.; Italiano, A.; Jiraskova, S.; Kadija, K.; Kaducak, M.; Kampert, K. H.; Karova, T.; Kasper, P.; K間l, B.; Keilhauer, B.; Keivani, A.; Kelley, J.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapik, R.; Knapp, J.; Koang, D.-H.; Krieger, A.; Kr鰉er, O.; Kruppke-Hansen, D.; Kuehn, F.; Kuempel, D.; Kulbartz, K.; Kunka, N.; Kusenko, A.; La Rosa, G.; Lachaud, C.; Lago, B. L.; Lautridou, P.; Le鉶, M. S. A. B.; Lebrun, D.; Lebrun, P.; Lee, J.; Leigui de Oliveira, M. A.; Lemiere, A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; L髉ez, R.; Lopez Ag黣ra, A.; Louedec, K.; Lozano Bahilo, J.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Macolino, C.; Maldera, S.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Maris, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Mart韓ez Bravo, O.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurizio, D.; Mazur, P. O.; McEwen, M.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Meurer, C.; Mi?anovi?, S.; Micheletti, M. I.; Miller, W.; Miramonti, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, E.; Moreno, J. C.; Morris, C.; Mostaf, M.; Mueller, S.; Muller, M. A.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Nhung, P. T.; Nierstenhoefer, N.; Nitz, D.; Nosek, D.; No瀔a, L.; Nyklicek, M.; Oehlschl鋑er, J.; Olinto, A.; Oliva, P.; Olmos-Gilbaja, V. M.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parizot, E.; Parlati, S.; Parra, A.; Parrisius, J.; Parsons, R. D.; Pastor, S.; Paul, T.; Pavlidou, V.; Payet, K.; Pech, M.; Pe?ala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrinca, P.; Petrolini, A.; Petrov, Y.; Petrovic, J.; Pfendner, C.; Piegaia, R.; Pierog, T.; Pimenta, M.; Pirronello, V.; Platino, M.; Ponce, V. H.; Pontz, M.; Privitera, P.; Prouza, M.; Quel, E. J.; Rautenberg, J.; Ravel, O.

    2010-01-01

    The surface detector array of the Pierre Auger Observatory consists of 1600 water-Cherenkov detectors, for the study of extensive air showers (EAS) generated by ultra-high-energy cosmic rays. We describe the trigger hierarchy, from the identification of candidate showers at the level of a single detector, amongst a large background (mainly random single cosmic ray muons), up to the selection of real events and the rejection of random coincidences. Such trigger makes the surface detector array fully efficient for the detection of EAS with energy above 31018eV, for all zenith angles between 0? and 60?, independently of the position of the impact point and of the mass of the primary particle. In these range of energies and angles, the exposure of the surface array can be determined purely on the basis of the geometrical acceptance.

  2. IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 50, NO. 5, MAY 2003 1233 Analysis of CMOS Photodiodes--Part I

    E-print Network

    Hornsey, Richard

    photodiode arrays. Index Terms--Active pixel sensor (APS), CMOS image sensor, CMOS photodiode, edgeIEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 50, NO. 5, MAY 2003 1233 Analysis of CMOS Photodiodes Abstract--An improved one-dimensional (1-D) analysis of CMOS photodiode has been derived in which

  3. Sensor modelling for the Cyclops focal plane detector array based technology demonstrator

    NASA Astrophysics Data System (ADS)

    Poropat, G. V.

    1992-12-01

    The Surveillance Research Laboratory of the DSTO has developed a technology demonstrator utilizing an infrared focal plane detector array to assess the feasibility of using large scale infrared detector arrays for ADF applications. The imaging sensor which has been developed requires no scanning mechanism and uses an array of mercury cadmium telluride detectors sensitive to radiation in the 8 um to 12 um spectral region to produce an image. The sensor was tested in a series of airborne trails and the results obtained from these trials will be used to evaluate the performance of focal plane detector array based systems. A mathematical model of the sensor has been used to evaluate the performance of the sensor. The mathematical model has been developed to meet the requirements imposed by analysis of the performance of this sensor. The model is based on the description of the operation of the elements of the detector array as photon counters. A description of the model used for the analysis of the data obtained using the sensor is presented here.

  4. Semiconductor detectors and focal plane arrays for far-infrared imaging

    NASA Astrophysics Data System (ADS)

    Rogalski, A.

    2013-12-01

    The detection of far-infrared (far-IR) and sub-mm-wave radiation is resistant to the commonly employed techniques in the neighbouring microwave and IR frequency bands. In this wavelength detection range the use of solid state detectors has been hampered for the reasons of transit time of charge carriers being larger than the time of one oscillation period of radiation. Also the energy of radiation quanta is substantially smaller than the thermal energy at room temperature and even liquid nitrogen temperature. The realization of terahertz (THz) emitters and receivers is a challenge because the frequencies are too high for conventional electronics and the photon energies are too small for classical optics. Development of semiconductor focal plane arrays started in seventies last century and has revolutionized imaging systems in the next decades. This paper presents progress in far-IR and sub-mm-wave semiconductor detector technology of focal plane arrays during the past twenty years. Special attention is given on recent progress in the detector technologies for real-time uncooled THz focal plane arrays such as Schottky barrier arrays, field-effect transistor detectors, and microbolometers. Also cryogenically cooled silicon and germanium extrinsic photoconductor arrays, and semiconductor bolometer arrays are considered.

  5. Quantum Well and Quantum Dot Modeling for Advanced Infrared Detectors and Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Ting, David; Gunapala, S. D.; Bandara, S. V.; Hill, C. J.

    2006-01-01

    This viewgraph presentation reviews the modeling of Quantum Well Infrared Detectors (QWIP) and Quantum Dot Infrared Detectors (QDIP) in the development of Focal Plane Arrays (FPA). The QWIP Detector being developed is a dual band detector. It is capable of running on two bands Long-Wave Infrared (LWIR) and Medium Wavelength Infrared (MWIR). The same large-format dual-band FPA technology can be applied to Quantum Dot Infrared Photodetector (QDIP) with no modification, once QDIP exceeds QWIP in single device performance. Details of the devices are reviewed.

  6. A YSO/LSO phoswich array detector for single and coincidence photon imaging

    SciTech Connect

    Dahlbom, M.; MacDonald, L.R. [Univ. of California, Los Angeles, CA (United States). School of Medicine] [Univ. of California, Los Angeles, CA (United States). School of Medicine; Schmand, M. [Max-Planck Inst. for Neurological Research, Cologne (Germany)] [Max-Planck Inst. for Neurological Research, Cologne (Germany); Eriksson, L. [Karolinska Hospital, Stockholm (Sweden). Dept. of Clinical Neurophysiology] [Karolinska Hospital, Stockholm (Sweden). Dept. of Clinical Neurophysiology; Andreaco, M.; Williams, C. [CTI Inc., Knoxville, TN (United States)] [CTI Inc., Knoxville, TN (United States)

    1998-06-01

    The performance of a phoswich array detector module for possible use in a combined single and coincidence photon imaging system has been evaluated. The assumption is that this detection module would allow the construction of a combined SPECT/PET imaging system with better count rate performance in the coincidence mode compared to current dual headed scintillation cameras. The detector consist of a linear array of discrete 4 x 4 x 15 mm{sup 3} YSO elements coupled to a combined detector array/light guide of LSO, 10 mm thick. Since the scintillation light decay time is different in YSO and LSO (70 and 40 ns, respectively), events originating from the two detector materials can be separated by pulse shape discrimination. The front layer of YSO could then be used for detection of low energy, single photon events and the LSO layer for coincidence detection of annihilation radiation. The light collection of the PMTs coupled to the detector was found to be adequate to accurately identify each detector element in the array using the same positioning logic used in conventional BGO block detectors. The average energy resolution of the YSO elements at 140 keV for the block detector was found to be 14.5% FWHM, ranging from 13.8 to 15.4%. Spatial resolution of the detector block in single photon mode, using a high resolution collimator (geometric resolution 6.5 mm at 10 cm) was measured by scanning a {sup 99m}Tc line source. The resolution at 5 and 10 cm from the collimator face was found to be 5.9 and 8.5 mm FWHM, respectively.

  7. Electro-Optical Characteristics of P+n In0.53Ga0.47As Hetero-Junction Photodiodes in Large Format Dense Focal Plane Arrays

    NASA Astrophysics Data System (ADS)

    DeWames, R.; Littleton, R.; Witte, K.; Wichman, A.; Bellotti, E.; Pellegrino, J.

    2015-03-01

    This paper is concerned with focal plane array (FPA) data and use of analytical and three-dimensional numerical simulation methods to determine the physical effects and processes limiting performance. For shallow homojunction P+n designs the temperature dependence of dark current for T < 300 K depends on the intrinsic carrier concentration of the In0.53Ga0.47As material, implying that the dominant dark currents are generation and recombination (G-R) currents originating in the depletion regions of the double layer planar heterostructure (DLPH) photodiode. In the analytical model differences from bulk G-R behavior are modeled with a G-R like perimeter-dependent shunt current conjectured to originate at the InP/InGaAs interface. In this description the fitting property is the effective conductivity, ? eff(T), in mho cm-1. Variation in the data suggests ? eff (300 K) values of 1.2 10-11-4.6 10-11 mho cm-1). Substrate removal extends the quantum efficiency (QE) spectral band into the visible region. However, dead-layer effects limit the QE to 10% at a wavelength of 0.5 ?m. For starlight-no moon illumination conditions, the signal-to-noise ratio is estimated to be 50 at an operating temperature of 300 K. A major result of the 3D numerical simulation of the device is the prediction of a perimeter G-R current not associated with the properties of the metallurgical interface. Another is the prediction that for a junction positioned in the larger band gap InP cap layer the QE is bias-dependent and that a relatively large reverse bias ?0.9 V is needed for the QE to saturate to the shallow homojunction value. At this higher bias the dark current is larger than the shallow homojunction value. The 3D numerical model and the analytical model agree in predicting and explaining the measured radiatively limited diffusion current originating at the n-side of the junction. The calculations of the area-dependent G-R current for the condition studied are also in agreement. Unique advantages of the 3D numerical simulation are the ability to mimic real device structures, achieve deeper understanding of the real physical effects associated with the various methods of junction formation, and predict how device designs will function.

  8. Measurement of the Proton-Air Cross Section with Telescope Array's Middle Drum Detector and Surface Array in Hybrid Mode

    E-print Network

    R. U. Abbasi; M. Abe; T. Abu-Zayyad; M. Allen; R. Anderson; R. Azuma; E. Barcikowski; J. W. Belz; D. R. Bergman; S. A. Blake; R. Cady; M. J. Chae; B. G. Cheon; J. Chiba; M. Chikawa; W. R. Cho; T. Fujii; M. Fukushima; T. Goto; W. Hanlon; Y. Hayashi; N. Hayashida; K. Hibino; K. Honda1; D. Ikeda; N. Inoue; T. Ishii; R. Ishimori; H. Ito; D. Ivanov; C. C. H. Jui; K. Kadota; F. Kakimoto; O. Kalashev; K. Kasahara; H. Kawai; S. Kawakami; S. Kawana; K. Kawata; E. Kido; H. B. Kim; J. H. Kim; J. H. Kim; S. Kitamura; Y. Kitamura; V. Kuzmin; Y. J. Kwon; J. Lan1; S. I. Lim; J. P. Lundquist; K. Machida; K. Martens; T. Matsuda; T. Matsuyama; J. N. Matthews; M. Minamino; K. Mukai; I. Myers; K. Nagasawa; S. Nagataki1; T. Nakamura; T. Nonaka; A. Nozato; S. Ogio; J. Ogura; M. Ohnishi; H. Ohoka; K. Oki; T. Okuda; M. Ono; A. Oshima; S. Ozawa; I. H. Park; M. S. Pshirkov; D. C. Rodriguez; G. Rubtsov; D. Ryu; H. Sagawa; N. Sakurai; A. L. Sampson; L. M. Scott; P. D. Shah; F. Shibata; T. Shibata; H. Shimodaira; B. K. Shin; J. D. Smith; P. Sokolsky; R. W. Springer; B. T. Stokes; S. R. Stratton; T. A. Stroman; T. Suzawa; M. Takamura; M. Takeda; R. Takeishi; A. Taketa; M. Takita; Y. Tameda; H. Tanaka; K. Tanaka; M. Tanaka; S. B. Thomas; G. B. Thomson; P. Tinyakov; I. Tkachev; H. Tokuno; T. Tomida; S. Troitsky; Y. Tsunesada; K. Tsutsumi; Y. Uchihori; S. Udo; F. Urban; G. Vasiloff; T. Wong; R. Yamane; H. Yamaoka; K. Yamazaki; J. Yang; K. Yashiro; Y. Yoneda; S. Yoshida; H. Yoshii; R. Zollinger; Z. Zundel

    2015-05-07

    In this work we are reporting on the measurement of the proton-air inelastic cross section $\\sigma^{\\rm inel}_{\\rm p-air}$ using the Telescope Array (TA) detector. Based on the measurement of the $\\sigma^{\\rm inel}_{\\rm p-air}$ the proton-proton cross section $\\sigma_{\\rm p-p}$ value is also determined at $\\sqrt{s} = 95$ TeV. Detecting cosmic ray events at ultra high energies with Telescope Array enables us to study this fundamental parameter that we are otherwise unable to access with particle accelerators. The data used in this report is collected over five years using hybrid events observed by the Middle Drum fluorescence detector together with the surface array detector. The value of the $\\sigma^{\\rm inel}_{\\rm p-air}$ is found to be equal to $ 567.0 \\pm 70.5 [{\\rm Stat.}] ^{+25}_{-29} [{\\rm Sys.}]$ mb. The total proton-proton cross section is subsequently inferred from Glauber Formalism and Block, Halzen and Stanev QCD inspired fit and is found to be equal to $170_{-44}^{+48} [{\\rm Stat.}] \\pm _{-19}^{+17} [{\\rm Sys.}] $mb.

  9. The Ultra-High Energy Cosmic Ray Spectrum Measured by the Telescope Array's Middle Drum Detector

    E-print Network

    Douglas Rodriguez; Matt Wood for the Telescope Array Collaboration

    2011-02-08

    The Telescope Array's Middle Drum fluorescence detector was constructed using refurbished telescopes from the High Resolution Fly's Eye (HiRes) experiment. As such, there is a direct comparison between these two experiments' fluorescence energy spectra. An energy spectrum has been calculated based on one year of collected data by the Middle Drum site of Telescope Array and agrees well with the HiRes monocular spectra. The quality of the Middle Drum results has also been determined to show good agreement.

  10. The Ultra-High Energy Cosmic Ray Spectrum Measured by the Telescope Array's Middle Drum Detector

    E-print Network

    Rodriguez, Douglas

    2011-01-01

    The Telescope Array's Middle Drum fluorescence detector was constructed using refurbished telescopes from the High Resolution Fly's Eye (HiRes) experiment. As such, there is a direct comparison between these two experiments' fluorescence energy spectra. An energy spectrum has been calculated based on one year of collected data by the Middle Drum site of Telescope Array and agrees well with the HiRes monocular spectra. The quality of the Middle Drum results has also been determined to show good agreement.

  11. The 20 element HgI2 energy dispersive x ray array detector system

    NASA Astrophysics Data System (ADS)

    Iwanczyk, J. A.; Dorri, N.; Wang, M.; Szczebiot, R. W.; Dabrowski, A. J.; Hedman, B.; Hodgson, K. O.; Patt, B. E.

    1991-11-01

    This paper describes recent progress in the development of HgI2 energy dispersive x-ray detector arrays and associated miniaturized processing electronics for synchrotron radiation research applications. The experimental results with a 20 element array detector were obtained under realistic synchrotron beam conditions at SSRL. An energy resolution of 250 eV (FWHM) at 5.9 keV (Mn-K(sub a)) was achieved. Energy resolution and throughput measurements versus input count rate and energy of incoming radiation have been measured. Extended X-ray Absorption Fine Structure (EXAFS) spectra were taken from diluted samples simulating proteins with nickel.

  12. Simulation of near-infrared photodiode detectors based on ?-FeSi2/4H-SiC heterojunctions

    NASA Astrophysics Data System (ADS)

    Pu, Hong-Bin; He, Xin; Quan, Ru-Dai; Cao, Lin; Chen, Zhi-Ming

    2013-03-01

    In this paper, we propose a near-infrared p-type ?-FeSi2/n-type 4H-SiC heterojunction photodetector with semiconducting silicide (?-FeSi2) as the active region for the first time. The optoelectronic characteristics of the photodetector are simulated using a commercial simulator at room temperature. The results show that the photodetector has a good rectifying character and a good response to near-infrared light. Interface states should be minimized to obtain a lower reverse leakage current. The response spectrum of the ?-FeSi2/4H-SiC detector, which consists of a p-type ?-FeSi2 absorption layer with a doping concentration of 1 1015 cm-3 and a thickness of 2.5 ?m, has a peak of 755 mA/W at 1.42 ?m. The illumination of the SiC side obtains a higher responsivity than that of the ?-FeSi2 side. The results illustrate that the ?-FeSi2/4H-SiC heterojunction can be used as a near-infrared photodetector compatible with near-infrared optically-activated SiC-based power switching devices.

  13. Circuit for high resolution decoding of multi-anode microchannel array detectors

    NASA Technical Reports Server (NTRS)

    Kasle, David B. (inventor)

    1995-01-01

    A circuit for high resolution decoding of multi-anode microchannel array detectors consisting of input registers accepting transient inputs from the anode array; anode encoding logic circuits connected to the input registers; midpoint pipeline registers connected to the anode encoding logic circuits; and pixel decoding logic circuits connected to the midpoint pipeline registers is described. A high resolution algorithm circuit operates in parallel with the pixel decoding logic circuit and computes a high resolution least significant bit to enhance the multianode microchannel array detector's spatial resolution by halving the pixel size and doubling the number of pixels in each axis of the anode array. A multiplexer is connected to the pixel decoding logic circuit and allows a user selectable pixel address output according to the actual multi-anode microchannel array detector anode array size. An output register concatenates the high resolution least significant bit onto the standard ten bit pixel address location to provide an eleven bit pixel address, and also stores the full eleven bit pixel address. A timing and control state machine is connected to the input registers, the anode encoding logic circuits, and the output register for managing the overall operation of the circuit.

  14. Germanium blocked-impurity-band detector arrays - Unpassivated devices with bulk substrates

    NASA Technical Reports Server (NTRS)

    Watson, Dan M.; Guptill, Matthew T.; Huffman, James E.; Krabach, Timothy N.; Raines, S. N.; Satyapal, Shobita

    1993-01-01

    We have fabricated and characterized six-element monolithic arrays of Ge:Ga blocked-impurity-band detectors, with threshold wavelength 220 microns, peak quantum efficiency 14 percent, detective quantum efficiency 9 percent, dark current 300 e(-)/s, and response uniformity better than 4 percent. The devices are described very well by the standard model of blocked-impurity-band detectors and appear to satisfy many of the requirements of low-background astronomical instruments.

  15. X-ray and gamma-ray imaging with monolithic CdZnTe detector arrays

    Microsoft Academic Search

    F. Patrick Doty; S. J. Friesenhahn; Jack F. Butler; Paul L. Hink

    1993-01-01

    CdZnTe crystals useful for room temperature x-ray astronomy detectors have recently been developed. Uniform response and good energy resolution in the 3 to 300 keV range have been demonstrated for large area detectors and monolithic arrays. Spectral resolution of 2.9 keV for the 59.5 keV (superscript 241)Am line, and resolved 661 keV peak from (superscript 137)Cs were recently achieved at

  16. The development and test of multi-anode microchannel array detector systems. 2: Soft X-ray detectors

    NASA Technical Reports Server (NTRS)

    Timothy, J. G.

    1983-01-01

    The techniques and procedures for producing very-large-format pulse-counting array detector systems for use in forthcoming high-energy astrophysics facilities were defined, and the structures and performance characteristics of high-sensitivity photocathodes for use at soft X-ray wavelengths between 100 and 1 A were determined. The progress made to date in each of these areas are described and the tasks that will be undertaken when the program is continued are summarized.

  17. NOY: a neutrino observatory network project based on stand alone air shower detector arrays

    NASA Astrophysics Data System (ADS)

    Montanet, F.; Lebrun, D.; Chauvin, J.; Lagorio, E.; Stassi, P.

    2011-09-01

    We have developed a self powered stand alone particle detector array dedicated to the observation of horizontal tau air showers induced by high energy neutrinos interacting in mountain rock. Air shower particle detection reaches a 100% duty cycle and is practically free of background when compared to Cherenkov light or radio techniques. It is thus better suited for rare neutrino event search. An appropriate mountain to valley topological configuration has been identified and the first array will be deployed on an inclined slope at an elevation of 1500 m facing Southern Alps near the city of Grenoble (France). A full simulation has been performed. A neutrino energy dependent mountain tomography chart is obtained using a neutrino and tau propagation code together with a detailed cartography and elevation map of the region. The array acceptance is then evaluated between 1 PeV and 100 EeV by simulating decaying tau air showers across the valley. The effective detection surface is determined by the shower lateral extension at array location and is hence much larger than the array geometrical area. The array exposure will be 1014 cm2 sr s at 100 PeV. Several independent arrays can be deployed with the aim of constituting a large distributed observatory. Some other sites are already under study. At last, special care is dedicated to the educational and outreach aspects of such a cosmic ray detector.

  18. Dual source and dual detector arrays tetrahedron beam computed tomography for image guided radiotherapy

    NASA Astrophysics Data System (ADS)

    Kim, Joshua; Lu, Weiguo; Zhang, Tiezhi

    2014-02-01

    Cone-beam computed tomography (CBCT) is an important online imaging modality for image guided radiotherapy. But suboptimal image quality and the lack of a real-time stereoscopic imaging function limit its implementation in advanced treatment techniques, such as online adaptive and 4D radiotherapy. Tetrahedron beam computed tomography (TBCT) is a novel online imaging modality designed to improve on the image quality provided by CBCT. TBCT geometry is flexible, and multiple detector and source arrays can be used for different applications. In this paper, we describe a novel dual source-dual detector TBCT system that is specially designed for LINAC radiation treatment machines. The imaging system is positioned in-line with the MV beam and is composed of two linear array x-ray sources mounted aside the electrical portal imaging device and two linear arrays of x-ray detectors mounted below the machine head. The detector and x-ray source arrays are orthogonal to each other, and each pair of source and detector arrays forms a tetrahedral volume. Four planer images can be obtained from different view angles at each gantry position at a frame rate as high as 20 frames per second. The overlapped regions provide a stereoscopic field of view of approximately 10-15 cm. With a half gantry rotation, a volumetric CT image can be reconstructed having a 45 cm field of view. Due to the scatter rejecting design of the TBCT geometry, the system can potentially produce high quality 2D and 3D images with less radiation exposure. The design of the dual source-dual detector system is described, and preliminary results of studies performed on numerical phantoms and simulated patient data are presented.

  19. Status of LWIR HgCdTe infrared detector technology

    NASA Technical Reports Server (NTRS)

    Reine, M. B.

    1990-01-01

    The performance requirements that today's advanced Long Wavelength Infrared (LWIR) focal plane arrays place on the HgCdTe photovoltaic detector array are summarized. The theoretical performance limits for intrinsic LWIR HgCdTe detectors are reviewed as functions of cutoff wavelength and operating temperature. The status of LWIR HgCdTe photovoltaic detectors is reviewed and compared to the focal plane array (FPA) requirements and to the theoretical limits. Emphasis is placed on recent data for two-layer HgCdTe PLE heterojunction photodiodes grown at Loral with cutoff wavelengths ranging between 10 and 19 microns at temperatures of 70 to 80 K. Development trends in LWIR HgCdTe detector technology are outlined, and conclusions are drawn about the ability for photovoltaic HgCdTe detector arrays to satisfy a wide variety of advanced FPA array applications.

  20. Extending the Astronomical Application of Photon Counting HgCdTe Linear Avalanche Photo-Diode Arrays to Low Background Space Observations.

    NASA Astrophysics Data System (ADS)

    Hall, Donald

    The high quantum efficiency and very low dark current, together with the ability to set the wavelength cutoff from one to far beyond 5.5 microns, of large format HAWAII HgCdTe arrays have already made them the workhorse for NASA space astronomy (and related) observations in the 1 to 5.5 micron infrared. They have performed outstandingly on Hubble Wide Field Camera 3 and WISE (and also Deep Impact/EPOXI and OCO-2) and are crucial to the two major NASA Astrophysics missions, JWST and WFIRST, and to Euclid. The proposed investigation seeks to extend these benefits to the most demanding observations those that seek to wring information from only a few photons (starved due to either the intrinsic faintness of the source or the need for high spectral or time resolution) or to discriminate a weak signature against a bright source. We will characterize, and optimize for space astronomy observations, the unique linear avalanche properties of HgCdTe photo-diodes (HgCdTe L-APDs) that allow noiseless (i.e. faithfully preserves the Poisson statistics of the incoming photons) avalanche multiplication of individual photo-electrons. 2.5 micron HgCdTe L-APD technology, developed for infrared eye-safe LIDAR and range gated imaging, is already benefiting infrared wavefront sensing for ground based adaptive optics. In HgCdTe the L-APD gain and the onset voltage for tunneling current are exponential functions of bandgap while also varying with cryogenic operating temperature. The unique HgCdTe bandgap engineering that allows tuning of the cutoff wavelength can be used to critically improve avalanche performance for specific applications. We will thoroughly evaluate avalanche performance at several representative bandgaps so as to allow model prediction of performance over the critical 1 to 5 micron spectral interval. The proposed investigation will hybridize modest 32x32 arrays of HgCdTe L-APDs to photon counting readouts already developed under another award and characterize their infrared photon counting performance at the low and ultra-low backgrounds required for NASA space astronomy missions. Specifically this will involve 1) Measuring the gain normalized dark count rate and avalanche gain of 2.5, 3.3 and 4 micron cutoff HgCdTe at cryogenic temperatures from 30 to 80 K and bias voltages up to 20 V, 2) Using these results to validate and refine models of avalanche gain along with generation- recombination and surface trap induced tunneling current in L-APD HgCdTe and, 3) Modeling the gain normalized dark count rate, surface tunneling current and avalanche gain of 2 to 5 micron cutoff HgCdTe L-APD arrays for astrophysics and other NASA missions. The overall objective of the investigation is to develop the tools to identify the sweet spot in bandgap and cryogenic operating temperature for each specific NASA astrophysics mission and to accurately predict ultimate performance. HgCdTe L-APD technology offers to NASA the ultimate performance for space astronomy in photon starved applications such as: 1) ultra-low background, extra- Zodiacal imaging and faint object spectroscopy from elliptical orbits beyond the asteroid belt with missions such as Extra-Zodiacal Explorer, 2) spectroscopy of the faintest O/IR sources from near earth and L-2 orbit at moderate to high resolution and, 3) time domain astronomy observations (photometric or spectral variations at frequencies above 1 Hz) of sources as diverse as close binaries, accretion disks, compact objects etc. HgCdTe L- APD arrays have the potential to enable new classes of missions and to bring critical observations within reach of the capabilities of the NASA SMD Astrophysics Explorer program. As they utilize the same mature TRL base as the large format JWST HgCdTe arrays, requiring only qualification of n-on-p material operated at higher bias voltages, the path to flight qualification is unusually direct.

  1. Plasmonic Nanoslit Array Enhanced Metal-Semiconductor-Metal Optical Detectors

    E-print Network

    Eryilmaz, Sukru Burc; Okyay, Ali K

    2014-01-01

    Metallic nanoslit arrays integrated on germanium metal-semiconductor-metal photodetectors show many folds of absorption enhancement for transverse-magnetic polarization in the telecommunication C-band. Such high enhancement is attributed to resonant interference of surface plasmon modes at the metal-semiconductor interface. Horizontal surface plasmon modes were reported earlier to inhibit photodetector performance. We computationally show, however, that horizontal modes enhance the efficiency of surface devices despite reducing transmitted light in the far field.

  2. Laboratory characterization of direct readout Si:Sb and Si:Ga infrared detector arrays

    NASA Technical Reports Server (NTRS)

    Mckelvey, Mark E.; Moss, Nicolas N.; Mcmurray, R. E., Jr.; Estrada, John A.; Goebel, John H.; Mccreight, Craig R.; Savage, Maureen L.; Junga, Frank; Whittemore, Thomas

    1989-01-01

    Highlights of recent results obtained at Ames Research Center in performance evaluations of infrared detector arrays are presented. Antimony- and gallium-doped silicon direct readout 58x62 element hybrid devices from Ames' ongoing detector technology development program are described. The observed characteristics meet most of the performance goals specified by the Space Infrared Telescope Facility (SIRTF) instrument teams and compare favorably with the best performance reported for discrete non-integrating extrinsic silicon detectors. Initial results of radiation environment testing are reported, and non-ideal behavior demonstrated by these test devices is discussed.

  3. Silicon Wafer-Scale Substrate for Microshutters and Detector Arrays

    NASA Technical Reports Server (NTRS)

    Jhabvala, Murzy; Franz, David E.; Ewin, Audrey J.; Jhabvala, Christine; Babu, Sachi; Snodgrass, Stephen; Costen, Nicholas; Zincke, Christian

    2009-01-01

    The silicon substrate carrier was created so that a large-area array (in this case 62,000+ elements of a microshutter array) and a variety of discrete passive and active devices could be mounted on a single board, similar to a printed circuit board. However, the density and number of interconnects far exceeds the capabilities of printed circuit board technology. To overcome this hurdle, a method was developed to fabricate this carrier out of silicon and implement silicon integrated circuit (IC) technology. This method achieves a large number of high-density metal interconnects; a 100-percent yield over a 6-in. (approximately equal to 15-cm) diameter wafer (one unit per wafer); a rigid, thermally compatible structure (all components and operating conditions) to cryogenic temperatures; re-workability and component replaceability, if required; and the ability to precisely cut large-area holes through the substrate. A method that would employ indium bump technology along with wafer-scale integration onto a silicon carrier was also developed. By establishing a silicon-based version of a printed circuit board, the objectives could be met with one solution. The silicon substrate would be 2 mm thick to survive the environmental loads of a launch. More than 2,300 metal traces and over 1,500 individual wire bonds are required. To mate the microshutter array to the silicon substrate, more than 10,000 indium bumps are required. A window was cut in the substrate to allow the light signal to pass through the substrate and reach the microshutter array. The substrate was also the receptacle for multiple unpackaged IC die wire-bonded directly to the substrate (thus conserving space over conventionally packaged die). Unique features of this technology include the implementation of a 2-mmthick silicon wafer to withstand extreme mechanical loads (from a rocket launch); integrated polysilicon resistor heaters directly on the substrate; the precise formation of an open aperture (approximately equal to 3x3cm) without any crack propagation; implementation of IR transmission blocking techniques; and compatibility with indium bump bonding. Although designed for the microshutter arrays for the NIRSpec instrument on the James Webb Space Telescope, these substrates can be linked to microshutter applications in the photomask generation and stepper equipment used to make ICs and microelectromechanical system (MEMS) devices.

  4. A cooled avalanche photodiode with high photon detection probability

    NASA Technical Reports Server (NTRS)

    Robinson, D. L.; Metscher, B. D.

    1986-01-01

    An avalanche photodiode has been operated as a photon-counting detector with 2 to 3 times the sensitivity of currently-available photomultiplier tubes. APD (avalanche photodiodes) detection probabilities that exceed 27% and approach 50% have been measured at an optimum operating temperature which minimizes noise. The sources of noise and their dependence on operating temperature and bias voltage are discussed.

  5. Multicolor focal plane array detector technology: a review

    Microsoft Academic Search

    M. Nurul Abedin; Tamer F. Refaat; Joseph M. Zawodny; Steve P. Sandford; Upendra N. Singh; Sumith V. Bandara; Sarath D. Gunapala; Ishwara Bhat; Norman P. Barnes

    2003-01-01

    A major concern today is to accurately measure CO2, O3, H2O, and CH4 in the atmosphere for the prediction of climate and weather. These measurements are critical for understanding the Earth's atmosphere, atmospheric chemistry, and systemic forcing driving climactic changes. For these measurements, detectors with high quantum efficiency and near background limited performance detectivity over a wide wavelength range are

  6. Multicolor Focal Plane Array Detector Technology: A Review

    Microsoft Academic Search

    M. Nurul Abedin; Tamer F. Refaat; Joseph Zawodny; Steve P. Sandford; Upendra N. Singh; Sumith Bandra; Sarath D. Gunapala; Ishwara Bhat; Norman P. Barnes

    2003-01-01

    A major concern today is to accurately measure CO2, O3, H2O, and CH4 in the atmosphere for the prediction of climate and weather. These measurements are critical for understanding the Earth's atmosphere, atmospheric chemistry, and systemic forces driving climactic changes. For these measurements, detectors with high quantum efficiency and near background limited performance detectivity over a wide wavelength range are

  7. Polycrystalline CVD diamond pixel array detector for nuclear particles monitoring

    NASA Astrophysics Data System (ADS)

    Pacilli, M.; Allegrini, P.; Girolami, M.; Conte, G.; Spiriti, E.; Ralchenko, V. G.; Komlenok, M. S.; Khomic, A. A.; Konov, V. I.

    2013-02-01

    We report the 90Sr beta response of a polycrystalline diamond pixel detector fabricated using metal-less graphitic ohmic contacts. Laser induced graphitization was used to realize multiple squared conductive contacts with 1mm 1mm area, 0.2 mm apart, on one detector side while on the other side, for biasing, a 9mm 9mm large graphite contact was realized. A proximity board was used to wire bonding nine pixels at a time and evaluate the charge collection homogeneity among the 36 detector pixels. Different configurations of biasing were experimented to test the charge collection and noise performance: connecting the pixel at the ground potential of the charge amplifier led to best results and minimum noise pedestal. The expected exponential trend typical of beta particles has been observed. Reversing the bias polarity the pulse height distribution (PHD) does not changes and signal saturation of any pixel was observed around 200V (0.4 V/?m). Reasonable pixels response uniformity has been evidenced even if smaller pitch 50100 ?m structures need to be tested.

  8. Dual energy imaging in mammography: Cross-talk study in a Si array detector

    E-print Network

    Ramello, Luciano

    Dual energy imaging in mammography: Cross-talk study in a Si array detector G. Baldazzi a , D.59.H; 87.59.E; 29.40.W Keywords: Medical imaging equipment; Digital radiography; Mammography; Solid mammography stands in the reduction of the dose released to patients and in the improvement of the contrast

  9. Implementation of an Affine-Covariant Feature Detector in Field-Programmable Gate Arrays

    E-print Network

    MacLean, W. James

    directions. While these features are not scale invariant, subsequent advances such as SIFT features [4, 5 different scales to provide scale invariance. Rotational invariance is usually achieved with a signature (orImplementation of an Affine-Covariant Feature Detector in Field-Programmable Gate Arrays Cristina

  10. Faraday cup detector array with electronic multiplexing for multichannel mass spectrometry

    Microsoft Academic Search

    A. A. Scheidemann; R. B. Darling; F. J. Schumacher; A. Isakharov

    2002-01-01

    A Faraday cup detector array (FCDA) and electronic multiplexing circuit have been developed for position sensitive ion beam detection. The entire FCDA always remains open to intercept the incident ion beam flux, and each cup is periodically and sequentially discharged through the electronic multiplexer. This produces true multichannel ion beam detection since none of the incident ion beam flux is

  11. Fabrication of large array of superconducting-tunnel-junction detectors for mass spectrometry

    Microsoft Academic Search

    Y. E. Chen; M. Ukibe; A. Kushino; M. Ohkubo

    2006-01-01

    Superconducting tunnel junction (STJ) detectors have a fast time response and a low threshold to detect such quanta as phonons. These characteristics are advantageous to their applications in mass spectrometry for large molecules. However, one drawback is small active area, which cancels out the high quantum efficiency for large molecules. In this study, therefore, arrays of 100 niobium-based proximized STJ

  12. Preamplifier development for superconducting tunnel junction array X-ray detector electronics

    Microsoft Academic Search

    W. K. Warburton; J. Harris; M. Carpenter; L. Fabris; S. Friedrich

    2010-01-01

    We have developed a very low noise preamplifier that meets the low-cost, high-density requirements for use with superconducting tunnel junction (STJ) arrays. The design allows the STJs' bias points to be digitally set at the ?V level. We then trace out noise versus bias curves under computer control and, by showing the correlation between this noise and detector energy resolution,

  13. Advances in mercuric iodide energy dispersive x-ray array detectors and associated miniaturized processing electronics (invited)

    NASA Astrophysics Data System (ADS)

    Iwanczyk, J. S.; Dorri, N.; Wang, M.; Szawlowski, M.; Warburton, W. K.; Hedman, B.; Hodgson, K. O.

    1989-07-01

    There are important areas of synchrotron radiation research which would strongly benefit from the availability of energy dispersive detector arrays with high energy resolution and good spatial resolution. The goal of this developmental project is to produce a several element mercuric iodide (HgI2) submodule, which can later be multiplied and grouped into larger arrays of 100-400 elements. A prototype five-element HgI2 array detector was constructed and tested using a synchrotron radiation beam at SSRL. An energy resolution of 280 eV (FWHM) has been obtained for the MnK? line at 5.9 keV. Miniaturized processing electronics were developed in parallel with array advancement. To date, we have completed the hybridized preamplifier and finished breadboarding a computer controlled amplifier. The system integration aspects of large array detectors were studied, producing a conceptual design for both the detector array and its computerized data-acquisition and analysis system.

  14. Digital Radiography and Computed Tomography Project -- Fully Integrated Linear Detector ArrayStatus Report

    SciTech Connect

    Tim Roney; Robert Seifert; Bob Pink; Mike Smith

    2011-09-01

    The field-portable Digital Radiography and Computed Tomography (DRCT) x-ray inspection systems developed for the Project Manager for NonStockpile Chemical Materiel (PMNSCM) over the past 13 years have used linear diode detector arrays from two manufacturers; Thomson and Thales. These two manufacturers no longer produce this type of detector. In the interest of insuring the long term viability of the portable DRCT single munitions inspection systems and to improve the imaging capabilities, this project has been investigating improved, commercially available detectors. During FY-10, detectors were evaluated and one in particular, manufactured by Detection Technologies (DT), Inc, was acquired for possible integration into the DRCT systems. The remainder of this report describes the work performed in FY-11 to complete evaluations and fully integrate the detector onto a representative DRCT platform.

  15. 112-Pixel Arrays of High-Efficiency STJ X-Ray Detectors

    NASA Astrophysics Data System (ADS)

    Friedrich, S.; Harris, J.; Warburton, W. K.; Carpenter, M. H.; Hall, J. A.; Cantor, R.

    2014-08-01

    We are developing the next generation of high-resolution high-speed X-ray detectors based on superconducting tunnel junctions (STJs). They consist of 112-pixel arrays of 208 m 208 m Ta-Al--Al-Ta tunnel junctions whose Ta absorber increases the detection efficiency compared to earlier Nb-based STJs. To read out these medium size detector arrays we have also developed a compact and scalable 32-channel preamplifier with an input voltage noise 1 nV/Hz and a dc voltage bias for stable STJ operation between Fiske mode resonances. The pixels have a uniform response across the array, an energy resolution between 7.5 and 9.5 eV FWHM at 525 eV, and can be operated at several 1,000 counts/s per pixel.

  16. CdZnTe and CdTe detector arrays for hard X-ray and gamma-ray astronomy

    Microsoft Academic Search

    C. M Stahle; B. H Parker; A. M Parsons; L. M Barbier; S. D Barthelmy; N. A Gehrels; D. M Palmer; S. J Snodgrass; J Tueller

    1999-01-01

    A variety of CdZnTe and CdTe detector arrays were fabricated at NASA\\/GSFC for use in hard X-ray and gamma-ray astronomy. Mosaic, pixel, and 3-D position-sensitive detector arrays were built to demonstrate the capabilities for high-resolution imaging and spectroscopy for 10 to 2MeV. This paper will summarize the different arrays and their applications for instruments being developed at NASA\\/GSFC. Specific topics

  17. Emerging contaminant determination in water samples by liquid chromatography using a monolithic column coupled with a photodiode array detector.

    PubMed

    Salvatierra-Stamp, Vilma Del C; Ceballos-Maga馻, Silvia G; Gonzalez, Jorge; Jurado, Jose M; Mu駃z-Valencia, Roberto

    2015-06-01

    Concern about the presence of emerging contaminants in the environment has increased because biological activity at low concentrations爃as been observed. The difficulty of detecting and quantifying these compounds encourages the development of analytical methods with highly sensitive and selective analytical procedures. Pharmaceuticals, pesticides, and industrial chemicals are used and finally discarded to the environment. This paper provides a rapid and sensitive analytical method for the quantification of eight emerging contaminants (carbamazepine, carbofuran, bisphenol A, diuron, 17 ? ethinylestradiol, ametryn, carbazole, and triclosan). A two-level full factorial design for optimization of chromatographic separation and sample preparation was performed. The separation using a monolithic column (Onyx C18) achieved baseline resolution for all compounds in 4.6爉in. The optimized sample treatment involved a preconcentration step by means of solid-phase extraction using HF Bond Elut-C18 cartridges, achieving an enrichment factor of 2222. Under optimum conditions, good linearity was obtained with a correlation coefficient higher than 0.999. The limits of detection and quantification for carbamazepine, carbofuran, bisphenol A, diuron, 17 ? ethinylestradiol, ametryn, and carbazole were in the range of 0.01-208.7 and 0.03-695.7爊g燣(-1), respectively, and for triclosan, the limit of detection and quantification was 0.67 and 2.25?g燣(-1), respectively. Precision evaluated as relative standard deviations was lower than 15%. The proposed method was found robust. Finally, the method was successfully applied to superficial water samples. PMID:25860655

  18. Simultaneous quantification of six main active constituents in Chinese Angelica by high-performance liquid chromatography with photodiode array detector

    PubMed Central

    Ying, Li; Si-Wang, Wang; Hong-Hai, Tu; Wei, Cao

    2013-01-01

    Background: Angelica sinensis is a famous traditional Chinese medicinalherb, which is predominantly used in the treatment of gynecological conditions. It is the first report for the simultaneous determination of six major active components in Chinese Angelica, which is important for quality control. Objective: A validated HPLC-PAD method was first developed to evaluate the quality of crude and processed Radix Angelica through simultaneous determination of six bioactive compounds, namely ferulic acid, senkyunolide I, senkyunolide H, coniferyl ferulate, Z/E-ligustilide and Z/E-butylidenephthalide. Materials and Methods: Samples were separated on a Xtimate機18 column (250 4.6 mm, 5 ?m) and detected by PAD. Mobile phase was composed of (A) aqueous phosphoric acid (0.02%, v/v) and (B) acetonitrile (MeCN) (including 10% tetrahydrofuran, v/v) using a gradient elution. Analytes were performed at 30癈 with a flow rate of 1.0 mL/min. Results: All calibration curves showed good linear regression (r2 ? 0.9963) within the tested ranges, and the recovery of the method was in the range of 91.927105.859%. Conclusion: The results demonstrate that the developed method is accurate and reproducible and could be readily utilized as a suitable quality control method for the quantification of Radix Angelica. PMID:23772106

  19. The Hybrid Energy Spectrum of TA's Middle Drum Detector and Surface Array

    E-print Network

    ,

    2014-01-01

    The Telescope Array experiment studies ultra high energy cosmic rays using a hybrid detector. Fluorescence telescopes measure the longitudinal development of the extensive air shower generated when a primary cosmic ray particle interacts with the atmosphere. Meanwhile, scintillator detectors measure the lateral distribution of secondary shower particles that hit the ground. The Middle Drum (MD) fluorescence telescope station consists of 14 telescopes from the High Resolution Fly's Eye (HiRes) experiment, providing a direct link back to the HiRes measurements. Using the scintillator detector data in conjunction with the telescope data improves the geometrical reconstruction of the showers significantly, and hence, provides a more accurate reconstruction of the energy of the primary particle. The Middle Drum hybrid spectrum is presented and compared to that measured by the Middle Drum station in monocular mode. Further, the hybrid data establishes a link between the Middle Drum data and the surface array. A com...

  20. Multiple detector focal plane array ultraviolet spectrometer for the AMPS laboratory

    NASA Technical Reports Server (NTRS)

    Feldman, P. D.

    1975-01-01

    The possibility of meeting the requirements of the amps spectroscopic instrumentation by using a multi-element focal plane detector array in a conventional spectrograph mount was examined. The requirements of the detector array were determined from the optical design of the spectrometer which in turn depends on the desired level of resolution and sensitivity required. The choice of available detectors and their associated electronics and controls was surveyed, bearing in mind that the data collection rate from this system is so great that on-board processing and reduction of data are absolutely essential. Finally, parallel developments in instrumentation for imaging in astronomy were examined, both in the ultraviolet (for the Large Space Telescope as well as other rocket and satellite programs) and in the visible, to determine what progress in that area can have direct bearing on atmospheric spectroscopy.

  1. Thermal IR imaging system using a self-scanned HgCdTe/CCD detector array

    NASA Technical Reports Server (NTRS)

    Husain-Abidi, A. S.; Ostrow, H.; Rubin, B.

    1980-01-01

    It is likely that future high resolution earth observation imaging systems will utilize self-scanned IR detectors. In an initial step toward this goal, an IR imaging system operating in the 10 to 12 micron spectral region has been developed. This system uses a 9-element HgCdTe/CCD linear array operating in the photoconductive mode, nine pre-amplifiers and a silicon CCD multiplexer integrated into a focal plane assembly. Opto-mechanical techniques are used to scan the scene and images are produced in real time. The imaging performance of this system is described and measurements of noise, responsivity, specific detectivity, and detector sensitivity profiles are presented. The requirements for more advanced detector arrays for use in future NASA remote sensing missions are also discussed.

  2. A linear array silicon pixel detector: images of a mammographic test object and evaluation of delivered doses

    Microsoft Academic Search

    F. Arfelli; V. Bonvicini; A. Bravin; G. Cantatore; E. Castelli; L. Dalla Palma; M. Di Michiel; R. Longo; A. Olivo; S. Pani; D. Pontoni; P. Poropat; M. Prest; A. Rashevsky; G. Tromba; A. Vacchi

    1997-01-01

    We present images of a mammographic test object obtained using a linear array silicon pixel detector capable of single-photon counting. The detector pixel size was and images were acquired by scanning the test object between the laminar detector and the x-ray source with a scanning step of . A molybdenum anode tube was used with two different filtrations: 2 mm

  3. Optical comparison of detector arrays from modulation transfer function measurements with laser speckle patterns

    NASA Astrophysics Data System (ADS)

    Fern醤dez-Oliveras, Alicia; Pozo, Antonio M.; Rubi駉, Manuel

    2012-04-01

    Charge-coupled device (CCD) and complementary metal-oxide semiconductor (CMOS) matrices offer excellent features in imaging systems. A suitability evaluation of either technology according to a specific application requires a complete characterization of the different detector types. A system is optically characterized by the modulation transfer function (MTF), which represents its response in spatial frequency of this system. One of the methods to measure the MTF uses a laser speckle pattern as the object. Here, we comparatively examine the results provided by the speckle method to determine the MTF for detectors of two types: CCD and CMOS. We generate the speckle pattern using a laser and an integrating sphere with an aperture at its exit port. The aperture determined the spatial-frequency content of the pattern registered in the detector. The precision in determining the MTF of the CCD was studied using two different apertures: a single-slit and a double-slit. For the single-slit, we propose a new procedure of fitting the experimental data which resolves the drawbacks of the conventional procedure. To study the CMOS detector, we used the single-slit because it offered lower uncertainty and better reproducibility. The differences between the MTF values of the CCD and the CMOS detectors proved significant for the spatial frequencies higher than 50 cycles/mm, which is half of the interval studied with both arrays. For these spatial frequencies, our results demonstrate that the CCD detector presented MTF values higher than those of the CMOS array.

  4. Underground Water Cherenkov Muon Detector Array with the Tibet Air Shower Array for Gamma-Ray Astronomy in the 100 TeV Region

    E-print Network

    Amenomori, M; Bi, X J; Chen, D; Cui, S W; Feng Zhao Yang; Danzengluobu; Ding, L K; Feng Cun Feng; Feng, Z; Feng, Z Y; Gao, X Y; Geng, Q X; Guo, H W; He, H H; He, M; Hibino, K; Hotta, N; Haibing, H; Hu, H B; Huang, J; Jia, H Y; Kajino, F; Kasahara, K; Katayose, Y; Kato, C; Kawata, K; Labaciren; Le, G M; Li, A F; Li, J Y; L, H; Lu, S L; Meng, X R; Mizutani, K; Mu, J; Munakata, K; Nagai, A; Nanj, H; Nishizawa, M; Ohnishi, M; Ohta, I; Onuma, H; Ouchi, T; Ozawa, S; Ren, J R; Sait, T; Saito, T Y; Sakata, M; Sako, T K; Sasaki, T; Shibata, M; Shiomi, A; Shirai, T; Sugimoto, H; Takita, M; Tan, Y H; Tateyama, N; Tori, S; Wang, B; Tsuchiya, H; Udo, S; Wang, X; Wang, Y G; Wu, H R; Xue Liang; Yamamoto, Y; Yan, C T; Yang, X C; Yasue, S; Ye, Z H; Yu, G C; Yuan, A F; Yuda, T; Zhang, H M; Zhamg, N J; Zhamg, X, Y; Zhamg, Y; Zhamg, Yi; Zha Xisang Zhu; Zhou, X X; al, et

    2006-01-01

    We propose to build a large water-Cherenkov-type muon-detector array (Tibet MD array) around the 37,000 m$^{2}$ Tibet air shower array (Tibet AS array) already constructed at 4,300 m above sea level in Tibet, China. Each muon detector is a waterproof concrete pool, 6 m wide $\\times$ 6 m long $\\times$ 1.5 m deep in size, equipped with a 20 inch-in-diameter PMT. The Tibet MD array consists of 240 muon detectors set up 2.5 m underground. Its total effective area will be 8,640 m$^{2}$ for muon detection. The Tibet MD array will significantly improve gamma-ray sensitivity of the Tibet AS array in the 100 TeV region (10-1000 TeV) by means of gamma/hadron separation based on counting the number of muons accompanying an air shower. The Tibet AS+MD array will have the sensitivity to gamma rays in the 100 TeV region by an order of magnitude better than any other previous existing detectors in the world.

  5. Speckle-based modulation transfer function measurements for comparative evaluation of CCD and CMOS detector arrays

    NASA Astrophysics Data System (ADS)

    Fern醤dez-Oliveras, Alicia; Pozo, Antonio M.; Rubi駉, Manuel

    2013-01-01

    Charge-coupled device (CCD) and complementary metal-oxide semiconductor (CMOS) matrices offer excellent features in imaging systems. For assessing the suitability of each technology according to the application, the complete characterization of the detector arrays becomes necessary. A system is optically characterized by the modulation transfer function (MTF). We have comparatively studied the results provided by the speckle method for detectors of two types: CCD and CMOS. To do so, we first analysed the precision in determining the MTF of the CCD using two apertures at the exit port of an integrating sphere: a single and a double-slit. For the single-slit, we propose a new procedure of fitting the experimental data which overcomes the drawbacks of the conventional procedure. Since it offered lower uncertainty and better reproducibility, the single-slit was used for the study with the CMOS detector. Significant differences were found between the MTF of the CCD and the CMOS detectors.

  6. Materials preparation and fabrication of pyroelectric polymer/silicon MOSFET detector arrays. Final report

    SciTech Connect

    Bloomfield, P. [Drexel Univ., Philadelphia, PA (United States). Dept. of Materials Engineering

    1992-03-27

    The authors have delivered several 64-element linear arrays of pyroelectric elements fully integrated on silicon wafers with MOS readout devices. They have delivered detailed drawings of the linear arrays to LANL. They have processed a series of two inch wafers per submitted design. Each two inch wafer contains two 64 element arrays. After spin-coating copolymer onto the arrays, vacuum depositing the top electrodes, and polarizing the copolymer films so as to make them pyroelectrically active, each wafer was split in half. The authors developed a thicker oxide coating separating the extended gate electrode (beneath the polymer detector) from the silicon. This should reduce its parasitic capacitance and hence improve the S/N. They provided LANL three processed 64 element sensor arrays. Each array was affixed to a connector panel and selected solder pads of the common ground, the common source voltage supply connections, the 64 individual drain connections, and the 64 drain connections (for direct pyroelectric sensing response rather than the MOSFET action) were wire bonded to the connector panel solder pads. This entails (64 + 64 + 1 + 1) = 130 possible bond connections per 64 element array. This report now details the processing steps and the progress of the individual wafers as they were carried through from beginning to end.

  7. Photodiode-Based X-Ray Beam-Position Monitor With High Spatial-Resolution for the NSLS-II Beamlines

    SciTech Connect

    Yoon, P.S.; Siddons, D. P.

    2009-05-25

    We developed a photodiode-based monochromatic X-ray beam-position monitor (X-BPM) with high spatial resolution for the project beamlines of the NSLS-II. A ring array of 32 Si PIN-junction photodiodes were designed for use as a position sensor, and a low-noise HERMES4 ASIC chip was integrated into the electronic readout system. A series of precision measurements to characterize electrically the Si-photodiode sensor and the ASIC chip demonstrated that the inherent noise is sufficiently below tolerance levels. Following up modeling of detector's performance, including geometrical optimization using a Gaussian beam, we fabricated and assembled a first prototype. In this paper, we describe the development of this new state-of-the-art X-ray BPM along the beamline, in particular, downstream from the monochromator.

  8. 3D Dose Verification Using Tomotherapy CT Detector Array

    SciTech Connect

    Sheng Ke, E-mail: ks2mc@virginia.edu [Department of Radiation Oncology, University of Virginia, Charlottesville, VA (United States); Jones, Ryan; Yang Wensha; Saraiya, Siddharth; Schneider, Bernard [Department of Radiation Oncology, University of Virginia, Charlottesville, VA (United States); Chen Quan; Sobering, Geoff; Olivera, Gustavo [TomoTherapy, Inc., Madison, WI (United States); Read, Paul [Department of Radiation Oncology, University of Virginia, Charlottesville, VA (United States)

    2012-02-01

    Purpose: To evaluate a three-dimensional dose verification method based on the exit dose using the onboard detector of tomotherapy. Methods and Materials: The study included 347 treatment fractions from 24 patients, including 10 prostate, 5 head and neck (HN), and 9 spinal stereotactic body radiation therapy (SBRT) cases. Detector sonograms were retrieved and back-projected to calculate entrance fluence, which was then forward-projected on the CT images to calculate the verification dose, which was compared with ion chamber and film measurement in the QA plans and with the planning dose in patient plans. Results: Root mean square (RMS) errors of 2.0%, 2.2%, and 2.0% were observed comparing the dose verification (DV) and the ion chamber measured point dose in the phantom plans for HN, prostate, and spinal SBRT patients, respectively. When cumulative dose in the entire treatment is considered, for HN patients, the error of the mean dose to the planning target volume (PTV) varied from 1.47% to 5.62% with a RMS error of 3.55%. For prostate patients, the error of the mean dose to the prostate target volume varied from -5.11% to 3.29%, with a RMS error of 2.49%. The RMS error of maximum doses to the bladder and the rectum were 2.34% (-4.17% to 2.61%) and 2.64% (-4.54% to 3.94%), respectively. For the nine spinal SBRT patients, the RMS error of the minimum dose to the PTV was 2.43% (-5.39% to 2.48%). The RMS error of maximum dose to the spinal cord was 1.05% (-2.86% to 0.89%). Conclusions: An excellent agreement was observed between the measurement and the verification dose. In the patient treatments, the agreement in doses to the majority of PTVs and organs at risk is within 5% for the cumulative treatment course doses. The dosimetric error strongly depends on the error in multileaf collimator leaf opening time with a sensitivity correlating to the gantry rotation period.

  9. Effects of intercrystal crosstalk on multielement LSO\\/APD PET detectors

    Microsoft Academic Search

    Paul Vaska; Sean P. Stoll; C. L. Woody; David J. Schlyer; Sepideh Shokouhi

    2003-01-01

    One of the most promising high resolution positron emission tomography detector designs comprises an array of small, optically isolated scintillator crystals each coupled to an independent photosensor, such as an avalanche photodiode (APD). However, crosstalk between crystals (due to Compton scatter, photoelectron escape, or incomplete optical isolation) can significantly degrade performance and is expected to increase as crystals become narrower

  10. Experiments with silicon array detectors in the RGO coude spectrograph

    NASA Astrophysics Data System (ADS)

    Harmer, C. F. W.; Harmer, D. L.

    Tests of two detectors, recently developed at the Royal Greenwich Observatory, are presented. An intensified reticon system which is used in a photon counting mode, and a directly illuminated cooled CID, were both tested on the coude spectrograph of the 30 in. telescope at Herstmonceux. The separation of component spectra in a composite star is examined by the reticon system, by observing spectral regions at about 4 A/mm in 58 Per and several giants with spectral types G9-K2. Beta Gem is then subtracted from 58 Per, and the resulting spectrum is presented. This system has been improved in terms of electronic stability, the transfer lens (now operating at full aperture), and the counts (linear to a few percent accuracy up to 3 photons/s/channel). The CID was tested for its potential in high resolution spectroscopy. It is found that improved accuracy could be achieved by illuminating more pixels along the slit, either by trailing or by utilizing a superpositioning image slicer. Starlink was a crucial element in the assessment of both systems.

  11. High-performance liquid chromatographic determination of acetyl-11-keto-alpha-boswellic acid, a novel pentacyclic triterpenoid, in plasma using a fluorinated stationary phase and photodiode array detection: application in pharmacokinetic studies.

    PubMed

    B點hele, Berthold; Zugmaier, Waltraud; Genze, Felicitas; Simmet, Thomas

    2005-12-27

    A rapid, sensitive and selective HPLC separation with photodiode array detection was developed for the analysis of the novel pentacyclic triterpenoid acetyl-11-keto-alpha-boswellic acid. Complete baseline separation of acetyl-11-keto-alpha-boswellic acid from the corresponding isomer acetyl-11-keto-beta-boswellic acid was achieved on a fluorinated stationary phase. The standard curve was linear from 0.98 nmol/l to 196 nmol/l acetyl-11-keto-alpha-boswellic acid. The compound was isolated from chick embryonic plasma using extraction on diatomaceous earth with an overall average extraction yield of 82%. This method was applied in a kinetic study on the chick chorioallantoic membrane model (CAM) and showed unequivocal separation between acetyl-11-keto-alpha-boswellic acid and acetyl-11-keto-beta-boswellic acid unachievable so far. PMID:16266833

  12. Pixel array detector for the capture of femtosecond duration x-ray images

    NASA Astrophysics Data System (ADS)

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

    2007-09-01

    An imaging Pixel Array Detector (PAD) is being developed to record x-ray scattering images from single particles at the SLAC Linac Coherent Light Source (LCLS) x-ray free electron laser. The LCLS will deliver x-ray pulses of 5-200 femtosecond duration 120 times per second. Proposed experiments require that the scatter from each pulse be independently recorded. This necessitates a detector with a charge integrating front-end because the high instantaneous arrival rate of photons (> 1000 photons per pixel in femtoseconds) exceeds the processing speed capabilities of digital counting detectors. Other capabilities of the PAD are a frame rate >120 Hz, a full-well depth in excess of 2000 8-keV photons, a detective quantum efficiency near unity, and the ability to readily differentiate between 0 and 1 photons per pixel. The detector will be a 4x4 array of subunit tiles. Each tile consists of two silicon chips solder-bump bonded together. A pixelated 500 micron thick, fully depleted silicon chip converts x-ray energy into charge carriers. The charge created is conveyed by solder connecting bumps to a CMOS ASIC in which each pixel has its own signal processing electronics. Each tile has ~190 x 190 pixels, resulting in a detector of > 760 x 760 pixels. Tests of prototype 16x16 readout pixel arrays show a read noise equivalent to 0.14 8-keV photons. Features of the detector include an in-pixel parallel 14-bit digitization scheme, and the capability to be configured with an adaptable, 2-level, 2D gain profile. The development of the read-out electronics and the effects of tiling on dead area are also discussed.

  13. Photoacoustic projection imaging using a 64-channel fiber optic detector array

    NASA Astrophysics Data System (ADS)

    Bauer-Marschallinger, Johannes; Felbermayer, Karoline; Bouchal, Klaus-Dieter; Veres, Istvan A.; Gr黱, Hubert; Burgholzer, Peter; Berer, Thomas

    2015-03-01

    In this work we present photoacoustic projection imaging with a 64-channel integrating line detector array, which average the pressure over cylindrical surfaces. For imaging, the line detectors are arranged parallel to each other on a cylindrical surface surrounding a specimen. Thereby, the three-dimensional imaging problem is reduced to a twodimensional problem, facilitating projection imaging. After acquisition of a dataset of pressure signals, a twodimensional photoacoustic projection image is reconstructed. The 64 channel line detector array is realized using optical fibers being part of interferometers. The parts of the interferometers used to detect the ultrasonic pressure waves consist of graded-index polymer-optical fibers (POFs), which exhibit better sensitivity than standard glass-optical fibers. Ultrasonic waves impinging on the POFs change the phase of light in the fiber-core due to the strain-optic effect. This phase shifts, representing the pressure signals, are demodulated using high-bandwidth balanced photo-detectors. The 64 detectors are optically multiplexed to 16 detection channels, thereby allowing fast imaging. Results are shown on a Rhodamine B dyed microsphere.

  14. Development of Yangbajing Air shower Core detector array for a new EAS hybrid Experiment

    E-print Network

    Jinsheng Liu; Jing Huang; Ding Chen; Ying Zhang; Liuming Zhai; Xu Chen; Xiaobin Hu; Yuhui Lin; Xueyao Zhang; Cunfeng Feng; Huanyu Jia; Xunxiu Zhou; DanZengLuoBu; Tianlu Chen; Haijin Li; Maoyuan Liu; Aifang Yuan

    2015-07-06

    Aiming at the observation of cosmic-ray chemical composition at the "knee" energy region, we have been developinga new type air-shower core detector (YAC, Yangbajing Air shower Core detector array) to be set up at Yangbajing (90.522$^\\circ$ E, 30.102$^\\circ$ N, 4300 m above sea level, atmospheric depth: 606 g/m$^2$) in Tibet, China. YAC works together with the Tibet air-shower array (Tibet-III) and an underground water cherenkov muon detector array (MD) as a hybrid experiment. Each YAC detector unit consists of lead plates of 3.5 cm thick and a scintillation counter which detects the burst size induced by high energy particles in the air-shower cores. The burst size can be measured from 1 MIP (Minimum Ionization Particle) to $10^{6}$ MIPs. The first phase of this experiment, named "YAC-I", consists of 16 YAC detectors each having the size 40 cm $\\times$ 50 cm and distributing in a grid with an effective area of 10 m$^{2}$. YAC-I is used to check hadronic interaction models. The second phase of the experiment, called "YAC-II", consists of 124 YAC detectors with coverage about 500 m$^2$. The inner 100 detectors of 80 cm $\\times $ 50 cm each are deployed in a 10 $\\times$ 10 matrix from with a 1.9 m separation and the outer 24 detectors of 100 cm $\\times$ 50 cm each are distributed around them to reject non-core events whose shower cores are far from the YAC-II array. YAC-II is used to study the primary cosmic-ray composition, in particular, to obtain the energy spectra of proton, helium and iron nuclei between 5$\\times$$10^{13}$ eV and $10^{16}$ eV covering the "knee" and also being connected with direct observations at energies around 100 TeV. We present the design and performance of YAC-II in this paper.

  15. Speckle spectroscopy; an application for the multi-anode microchannel array detector system

    NASA Technical Reports Server (NTRS)

    Butcher, H. R.; Joseph, C. L.; Timothy, J. G.

    1982-01-01

    Plans to combine the High Angular Resolution Imager/Spectrometer on the 4-meter Mayall telescope at the Kitt Peak National Observatory and the (256 x 1024)-pixel Multi-Anode Microchannel Array detector system to produce a unique instrument for speckle spectroscopy are described. The pulse-counting detector system will provide distortion-free imaging and will time tag each spatially-resolved photon event with an accuracy of 100 ns. The Imager/Spectrometer will provide a spatial resolution of 0.07 arcsec orthogonal to the plane of dispersion and 0.18 arcsec in the plane of dispersion.

  16. High-dynamic-range coherent diffractive imaging: ptychography using the mixed-mode pixel array detector

    PubMed Central

    Giewekemeyer, Klaus; Philipp, Hugh T.; Wilke, Robin N.; Aquila, Andrew; Osterhoff, Markus; Tate, Mark W.; Shanks, Katherine S.; Zozulya, Alexey V.; Salditt, Tim; Gruner, Sol M.; Mancuso, Adrian P.

    2014-01-01

    Coherent (X-ray) diffractive imaging (CDI) is an increasingly popular form of X-ray microscopy, mainly due to its potential to produce high-resolution images and the lack of an objective lens between the sample and its corresponding imaging detector. One challenge, however, is that very high dynamic range diffraction data must be collected to produce both quantitative and high-resolution images. In this work, hard X-ray ptychographic coherent diffractive imaging has been performed at the P10 beamline of the PETRA?III synchrotron to demonstrate the potential of a very wide dynamic range imaging X-ray detector (the Mixed-Mode Pixel Array Detector, or MM-PAD). The detector is capable of single photon detection, detecting fluxes exceeding 1 108 8-keV photons pixel?1 s?1, and framing at 1?kHz. A ptychographic reconstruction was performed using a peak focal intensity on the order of 1 1010?photons 祄?2 s?1 within an area of approximately 325?nm 603?nm. This was done without need of a beam stop and with a very modest attenuation, while 憇till images of the empty beam far-field intensity were recorded without any attenuation. The treatment of the detector frames and CDI methodology for reconstruction of non-sensitive detector regions, partially also extending the active detector area, are described. PMID:25178008

  17. Photodiode and photomultiplier areal sensitivity anomalies

    NASA Technical Reports Server (NTRS)

    Youngbluth, O., Jr.

    1977-01-01

    Several silicon photodiodes and photomultipliers were tested to determine signal variations as a light spot was scanned over the photosensitive surface of these detectors. Qualitative and quantitative data is presented to demonstrate the areal sensitivity anomalies. These anomalies are related back to the fabrication techniques of the manufacturers.

  18. Photo sensor array technology development

    NASA Technical Reports Server (NTRS)

    Rossman, M. W.; Young, V. F.; Beall, J. R.

    1977-01-01

    The development of an improved capability photo sensor array imager for use in a Viking '75 type facsimile camera is presented. This imager consists of silicon photodiodes and lead sulfide detectors to cover a spectral range from 0.4 to 2.7 microns. An optical design specifying filter configurations and convergence angles is described. Three electronics design approaches: AC-chopped light, DC-dual detector, and DC-single detector, are investigated. Experimental and calculated results are compared whenever possible using breadboard testing and tolerance analysis techniques. Results show that any design used must be forgiving of the relative instability of lead sulfide detectors. A final design using lead sulfide detectors and associated electronics is implemented by fabrication of a hybrid prototype device. Test results of this device show a good agreement with calculated values.

  19. Acceptance and Angular Resolution of an Infill Array for the Pierre Auger Surface Detector

    SciTech Connect

    Medina, C. [Tandar Laboratory (CAC - CNEA), Buenos Aires (Argentina); Gomez Berisso, M.; Allekotte, I. [I. Balseiro and Centro Atomico Bariloche (CNEA), Bariloche (Argentina); Etchegoyen, A.; Supanitsky, D. [Tandar Laboratory (CAC - CNEA), Buenos Aires (Argentina); CONICET, Buenos Aires (Argentina); Medina-Tanco, G. [I. Astronomico e Geofisico, Univ. de Sao Paulo, Sao Paulo (Brazil)

    2007-02-12

    The Pierre Auger Observatory has been designed to study the highest-energy cosmic rays in nature (E {>=} 1019 eV). The determination of their arrival direction, energy and composition is performed by the analysis of the atmospheric showers they produce. The Auger Surface Array will consist of 1600 water Cerenkov detectors placed in an equilateral triangular grid of 1.5 km. In this paper we show how adding a ''small'' area of surface detectors at half the above mentioned spacing would make it possible to lower the detection threshold by one order of magnitude, thus allowing the Observatory to reach lower energies where the cross-over from galactic to extragalactic sources is expected. We also analyze the angular resolution that can be attained with such an infill array.

  20. DALI2: A NaI(Tl) detector array for measurements of ? rays from fast nuclei

    NASA Astrophysics Data System (ADS)

    Takeuchi, S.; Motobayashi, T.; Togano, Y.; Matsushita, M.; Aoi, N.; Demichi, K.; Hasegawa, H.; Murakami, H.

    2014-11-01

    A NaI(Tl) detector array called DALI2 (Detector Array for Low Intensity radiation 2) has been constructed for in-beam ?-ray spectroscopy experiments with fast radioactive isotope (RI) beams. It consists typically of 186 NaI(Tl) scintillators covering polar angles from ~15 to ~160 with an average angular resolution of 6 in full width at half maximum. Its high granularity (good angular resolution) enables Doppler-shift corrections that result in, for example, 10% energy resolution and 20% full-energy photopeak efficiency for 1-MeV ? rays emitted from fast-moving nuclei (velocities of v/c?0.6). DALI2 has been employed successfully in numerous experiments using fast RI beams with velocities of v/c=0.3-0.6 provided by the RIKEN RI Beam Factory.

  1. The cosmology large angular scale surveyor (CLASS): 38-GHz detector array of bolometric polarimeters

    NASA Astrophysics Data System (ADS)

    Appel, John W.; Ali, Aamir; Amiri, Mandana; Araujo, Derek; Bennet, Charles L.; Boone, Fletcher; Chan, Manwei; Cho, Hsiao-Mei; Chuss, David T.; Colazo, Felipe; Crowe, Erik; Denis, Kevin; D黱ner, Rolando; Eimer, Joseph; Essinger-Hileman, Thomas; Gothe, Dominik; Halpern, Mark; Harrington, Kathleen; Hilton, Gene; Hinshaw, Gary F.; Huang, Caroline; Irwin, Kent; Jones, Glenn; Karakula, John; Kogut, Alan J.; Larson, David; Limon, Michele; Lowry, Lindsay; Marriage, Tobias; Mehrle, Nicholas; Miller, Amber D.; Miller, Nathan; Moseley, Samuel H.; Novak, Giles; Reintsema, Carl; Rostem, Karwan; Stevenson, Thomas; Towner, Deborah; U-Yen, Kongpop; Wagner, Emily; Watts, Duncan; Wollack, Edward; Xu, Zhilei; Zeng, Lingzhen

    2014-07-01

    The Cosmology Large Angular Scale Surveyor (CLASS) experiment aims to map the polarization of the Cosmic Microwave Background (CMB) at angular scales larger than a few degrees. Operating from Cerro Toco in the Atacama Desert of Chile, it will observe over 65% of the sky at 38, 93, 148, and 217 GHz. In this paper we discuss the design, construction, and characterization of the CLASS 38 GHz detector focal plane, the first ever Q-band bolometric polarimeter array.

  2. Noise analysis and performance of a selfscanned linear InSb detector array

    Microsoft Academic Search

    G. Finger; M. Meyer; A. F. M. Moorwood

    1987-01-01

    A noise model for detectors operated in the capacitive discharge mode is presented. It is used to analyze the noise performance of the ESO nested timing readout technique applied to a linear 32-element InSb array which is multiplexed by a silicon switched-FET shift register. Analysis shows that KTC noise of the video line is the major noise contribution; it can

  3. The multi-element mercuric iodide detector array with computer controlled miniaturized electronics for EXAFS

    Microsoft Academic Search

    B. E. Patt; J. S. Iwanczyk; R. Szczebiot; G. Maculewicz; M. Wang; Y. J. Wang; B. Hedman; K. O. Hodgson; A. D. Cox

    1995-01-01

    Construction of a 100-element HgI2 detector array, with miniaturized electronics, and software developed for synchrotron applications in the 5 keV to 35 keV region has been completed. Recently, extended X-ray absorption fine structure (EXAFS) data on dilute (~1 mM) metallo-protein samples were obtained with up to seventy-five elements of the system installed. The data quality obtained is excellent and shows

  4. The Long Wavelength Array: A Ground-Based Coronal Mass Ejection Detector

    Microsoft Academic Search

    T. J. W. Lazio; N. E. Kassim; P. Rodriguez; N. Gopalswamy; W. C. Erickson

    1999-01-01

    We describe the Long Wavelength Array (LWA), a ground-based radio interferometer capable of serving as a coronal mass ejection (CME) detector. Previous low-frequency (nu < 50 MHz) coronal sounding experiments have shown that CMEs exhibit large radar cross sections. The LWA will serve as the imaging receiver for a bi-static radar observatory that will open an entirely new field of

  5. Digital data acquisition modules for instrumenting large segmented germanium detector arrays

    Microsoft Academic Search

    Hui Tan; Wolfgang Hennig; Mark Walby; Anthony Fallu-Labruyere; Jack Harris; Dimitry Breus; Peter Grudberg; William K. Warburton; Constantin Vaman; Thomas Glasmacher; Paul Mantica; David Miller; Krzysztof Starosta; Philip Voss

    2008-01-01

    XIA LLC has developed a 16-channel digital gamma-ray spectrometer (DGF Pixie-16) and associated electronics for instrumenting segmented germanium detector systems with large numbers of channels. The Pixie-16 is a CompactPCI\\/PXI-based data acquisition module equipped with 100 MHz 12-bit digitizers, signal processing field programmable gate arrays and a digital signal processor. Housed in a custom 6U PXI chassis, its operation can

  6. Feasibility study of a compact high resolution dual layer LSO-APD detector module for positron emission tomography

    Microsoft Academic Search

    B. J. Pichler; G. Boning; M. Rafecas; W. Pimpl; E. Korenz; M. Schwaiger; S. I. Ziegler

    1998-01-01

    An existing high resolution scanner for positron emission tomography (PET) of small animals was modified to investigate a scheme of depth-of-interaction (DOI) detection. The detectors were based on the readout of small (3.73.712 mm3) lutetium oxyorthosilicate (LSO) crystals with avalanche photodiodes (APD). For DOI measurements, 4 detector modules (arrays of 28 LSO-APD detectors) were mounted on a rotatable gantry in

  7. Microelectrode arrays with overlapped diffusion layers as electroanalytical detectors: theory and basic applications.

    PubMed

    Tom?韐, Peter

    2013-01-01

    This contribution contains a survey of basic literature dealing with arrays of microelectrodes with overlapping diffusion layers as prospective tools in contemporary electrochemistry. Photolithographic thin layer technology allows the fabrication of sensors of micrometric dimensions separated with a very small gap. This fact allows the diffusion layers of single microelectrodes to overlap as members of the array. Various basic types of microelectrode arrays with interacting diffusion layers are described and their analytical abilities are accented. Theoretical approaches to diffusion layer overlapping and the consequences of close constitution effects such as collection efficiency and redox cycling are discussed. Examples of basis applications in electroanalytical chemistry such as amperometric detectors in HPLC and substitutional stripping voltammetry are also given. PMID:24152927

  8. Performance of charge-injection-device infrared detector arrays at low and moderate backgrounds

    NASA Technical Reports Server (NTRS)

    Mckelvey, M. E.; Mccreight, C. R.; Goebel, J. H.; Reeves, A. A.

    1985-01-01

    Three 2 x 64 element charge injection device infrared detector arrays were tested at low and moderate background to evaluate their usefulness for space based astronomical observations. Testing was conducted both in the laboratory and in ground based telescope observations. The devices showed an average readout noise level below 200 equivalent electrons, a peak responsivity of 4 A/W, and a noise equivalent power of 3x10 sq root of W/Hz. Array well capacity was measured to be significantly smaller than predicted. The measured sensitivity, which compares well with that of nonintegrating discrete extrinsic silicon photoconductors, shows these arrays to be useful for certain astronomical observations. However, the measured readout efficiency and frequency response represent serious limitations in low background applications.

  9. Microelectrode Arrays with Overlapped Diffusion Layers as Electroanalytical Detectors: Theory and Basic Applications

    PubMed Central

    Tom?韐, Peter

    2013-01-01

    This contribution contains a survey of basic literature dealing with arrays of microelectrodes with overlapping diffusion layers as prospective tools in contemporary electrochemistry. Photolithographic thin layer technology allows the fabrication of sensors of micrometric dimensions separated with a very small gap. This fact allows the diffusion layers of single microelectrodes to overlap as members of the array. Various basic types of microelectrode arrays with interacting diffusion layers are described and their analytical abilities are accented. Theoretical approaches to diffusion layer overlapping and the consequences of close constitution effects such as collection efficiency and redox cycling are discussed. Examples of basis applications in electroanalytical chemistry such as amperometric detectors in HPLC and substitutional stripping voltammetry are also given. PMID:24152927

  10. Experimental study of double beta decay modes using a CdZnTe detector array

    E-print Network

    J. V. Dawson; C. Goessling; B. Janutta; M. Junker; T. Koettig; D. Muenstermann; S. Rajek; C. Reeve; O. Schulz; J. R. Wilson; K. Zuber

    2009-09-25

    An array of sixteen 1 cm^3 CdZnTe semiconductor detectors was operated at the Gran Sasso Underground Laboratory (LNGS) to further investigate the feasibility of double-beta decay searches with such devices. As one of the double-beta decay experiments with the highest granularity the 4 x 4 array accumulated an overall exposure of 18 kg days. The setup and performance of the array is described. Half-life limits for various double-beta decay modes of Cd, Zn and Te isotopes are obtained. No signal has been found, but several limits beyond 10^20 years have been performed. They are an order of magnitude better than those obtained with this technology before and comparable to most other experimental approaches for the isotopes under investigation. An improved limit for the beta^+/EC decay of Te 120 is given.

  11. The role of localized junction leakage in the temperature-dependent laser-beam-induced current spectra for HgCdTe infrared focal plane array photodiodes

    SciTech Connect

    Feng, A. L.; Li, G., E-mail: liguang1971@ahu.edu.cn, E-mail: xschen@mail.sitp.ac.cn; He, G.; Sun, Z. Q. [School of Physics and Materials Science and Anhui Key Laboratory of Information Materials and Devices, Anhui University, Hefei 230601 (China); Hu, W. D.; Chen, X. S., E-mail: liguang1971@ahu.edu.cn, E-mail: xschen@mail.sitp.ac.cn; Yin, F.; Zhang, B.; Lu, W. [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China)

    2013-11-07

    We have performed the study on the dependence of laser beam induced current (LBIC) spectra on the temperature for the vacancy-doped molecular beam epitaxy grown Hg{sub 1?x}Cd{sub x}Te (x?=?0.31) photodiodes by both experiment and numerical simulations. It is found that the measured LBIC signal has different distributions for different temperature extents. The LBIC profile tends to be more asymmetric with increasing temperature below 170?K. But the LBIC profile becomes more symmetric with increasing temperature above 170?K. Based on a localized leakage model, it is indicated that the localized junction leakage can lead to asymmetric LBIC signal, in good agreement with the experimental data. The reason is that the trap-assisted tunneling current is the dominant leakage current at the cryogenic temperature below 170?K while the diffusion current component becomes dominant above the temperature of 170?K. The results are helpful for us to better clarify the mechanism of the dependence of LBIC spectra on temperature for the applications of HgCdTe infrared photodiodes.

  12. The role of localized junction leakage in the temperature-dependent laser-beam-induced current spectra for HgCdTe infrared focal plane array photodiodes

    NASA Astrophysics Data System (ADS)

    Feng, A. L.; Li, G.; He, G.; Sun, Z. Q.; Hu, W. D.; Chen, X. S.; Yin, F.; Zhang, B.; Lu, W.

    2013-11-01

    We have performed the study on the dependence of laser beam induced current (LBIC) spectra on the temperature for the vacancy-doped molecular beam epitaxy grown Hg1-xCdxTe (x = 0.31) photodiodes by both experiment and numerical simulations. It is found that the measured LBIC signal has different distributions for different temperature extents. The LBIC profile tends to be more asymmetric with increasing temperature below 170 K. But the LBIC profile becomes more symmetric with increasing temperature above 170 K. Based on a localized leakage model, it is indicated that the localized junction leakage can lead to asymmetric LBIC signal, in good agreement with the experimental data. The reason is that the trap-assisted tunneling current is the dominant leakage current at the cryogenic temperature below 170 K while the diffusion current component becomes dominant above the temperature of 170 K. The results are helpful for us to better clarify the mechanism of the dependence of LBIC spectra on temperature for the applications of HgCdTe infrared photodiodes.

  13. Pixel Array Detector for Time-Resolved X-ray Science, September 1, 1997 - September 14, 2000

    SciTech Connect

    Gruner, Sol M.

    2000-11-07

    Progress on the design, fabrication, testing and assembly of two-layer Pixel Array Detectors (PADs) is described. The PADs are developed for challenging time-resolved X-ray imaging applications at synchrotron radiation X-ray sources.

  14. Development of Ta-based STJ X-ray Detector Arrays for Synchrotron Science

    NASA Astrophysics Data System (ADS)

    Carpenter, M. H.; Friedrich, S.; Hall, J. A.; Harris, J.; Cantor, R.

    2014-08-01

    We are developing a cryogen-free Ta-based superconducting tunnel junction (STJ) detector for soft X-ray spectroscopy at synchrotrons. With an energy resolution 10 times higher than conventional solid-state X-ray detectors and count-rate capabilities above 5 kHz/pixel, STJ detectors offer potentially increased sensitivity for fluorescence-yield X-ray absorption spectroscopy (FY-XAS). We have developed 36-pixel arrays of 208 208 m Ta STJs with an energy resolution of 9 eV FWHM at the 525 eV oxygen K line. Compared to earlier Nb-based STJs, Ta-STJs offer improved energy resolution and absorption efficiency and extend the operating range to several keV. Here we describe the integration of the 36-pixel arrays into a cryogen-free, user-friendly X-ray spectrometer. A computer-controlled adiabatic demagnetization refrigerator coupled to a two-stage pulse tube refrigerator allows operation below 100 mK. The detector chip is located at the end of a 42 cm shielded snout for insertion into the analysis chamber. The system is currently being commissioned at the Advanced Light Source synchrotron.

  15. Characterization of Nanometer Step Structure Formation During the Fabrication of Large-Scale Superconducting-Tunnel-Junction Array Detectors

    Microsoft Academic Search

    Masahiro Ukibe; Akira Kurokawa; Masataka Ohkubo

    2009-01-01

    Superconducting-tunnel-junction (STJ) array detectors with an effective sensitive area of 4 mm2 were fabricated for mass spectrometry. An array detector has one hundred Nb\\/Al\\/AlOx\\/Al\\/Nb junctions with a 200 mum-square sensitive area. The junctions are quasi-horizontally arranged on a 10 mm-square chip. In the course of fabrication processes, we have found that an anomalous nanometer-step structure appears within the junctions located

  16. Cooled avalanche photodiode used for photon detection

    NASA Technical Reports Server (NTRS)

    Robinson, Deborah L.; Metscher, Brian D.

    1987-01-01

    Commercial avalanche photodiodes have been operated as single-photon detectors at an optimum operating temperature and bias voltage. These detectors were found to be 1.5 to 3 times more sensitive than presently-available photomultiplier tubes (PPMTs). Both single-photon detection probability and detector noise increase with bias voltage; detection probabilities greater than 25 percent were obtained with detector noise levels comparable to the noise of a PMT; higher probabilities were measured at higher noise levels. The sources of noise and their dependence on temperature and bias voltage are discussed.

  17. Photon detection with cooled avalanche photodiodes

    NASA Technical Reports Server (NTRS)

    Robinson, D. L.; Metscher, B. D.

    1987-01-01

    Commercial avalanche photodiodes have been operated as single-photon detectors at an optimum operating temperature and bias voltage. These detectors were found to be 1.5-3 times more sensitive than presently available photomultiplier tubes (PMTs). Both single-photon detection probability and detector noise increase with bias voltage; detection probabilities greater than twice that of a PMT were obtained with detector noise levels below 100 counts per second. Higher probabilities were measured at higher noise levels. The sources of noise and their dependence on temperature and bias voltage are discussed.

  18. Low-flux measurements with Cornell's LCLS integrating pixel array detector

    NASA Astrophysics Data System (ADS)

    Philipp, Hugh T.; Tate, Mark W.; Gruner, Sol M.

    2011-11-01

    Next generation light sources are revolutionizing x-ray science by delivering ultra-intense, hard x-ray pulses many orders of magnitude brighter and shorter in duration than previously achievable. Maximizing the scientific potential of these light sources requires the development of suitable detectors. Experiments such as coherent x-ray imaging of single particles require detectors that can record extremely high instantaneous flux rates produced by femtosecond x-ray pulses (i.e. thousands of photons incident on a single pixel of an area detector in a few femtoseconds) while also being able to accurately distinguish single photon events so that many thousands of frames of data can be used to reconstruct extremely low flux information (e.g. less than 1/1000 photons per pixel per frame). This paper presents data from an integrating pixel array detector (PAD) possessing the ability to record high- and low-flux x-ray data at an X-ray Free Electron Laser (XFEL). Methods are presented to process extremely low-flux data (less than 1/10000 8-keV x-rays per pixel per frame) to accurately recover diffraction patterns from thousands of frames. The data were collected using a detector developed by Cornell for the Linac Coherent Light Source (LCLS) at SLAC National Lab. A copy of this detector was delivered to SLAC in the middle of 2008. The ASIC developed for this detector was used by SLAC as the basis for the CS-PAD (Cornell SLAC-PAD) being used on the Coherent X-ray Imaging beamline at the LCLS. These methods extend beyond XFEL applications because they allow for the suppression of dark accumulation noise which typically limits the low-flux capability of integrating detectors on conventional x-ray sources.

  19. Two dimensional extensible array configuration for EMCCD-based solid state x-ray detectors.

    PubMed

    Sharma, P; Vasan, S N Swetadri; Cartwright, A N; Titus, A H; Bednarek, D R; Rudin, S

    2012-01-01

    We have designed and developed from the discrete component level a high resolution dynamic x- ray detector to be used for fluoroscopic and angiographic medical imaging. The heart of the detector is a 1024 1024 pixel electron multiplying charge coupled device (EMCCD) with a pixel size of 13 13 ?m(2) (Model CCD201-20, e2v Technologies, Inc.), bonded to a fiber optic plate (FOP), and optically coupled to a 350 ?m thick micro-columnar CsI(TI) scintillator via a fiber optic taper (FOT). Our aim is to design an array of these detectors that could be extended to any arbitrary X Y size in two dimensions to provide a larger field of view (FOV). A physical configuration for a 33 array is presented that includes two major sub-systems. First is an optical front end that includes (i) a phosphor to convert the x-ray photons into light photons, and (ii) a fused array of FOTs that focuses light photons from the phosphor onto an array of EMCCD's optically coupled using FOPs. Second is an electronic front end that includes (i) an FPGA board used for generating clocks and for data acquisition (ii) driver boards to drive and digitize the analog output from the EMCCDs, (iii) a power board, and (iv) headboards to hold the EMCCD's while they are connected to their respective driver board using flex cables. This configuration provides a larger FOV as well as region-of- interest (ROI) high-resolution imaging as required by modern neurovascular procedures. PMID:22822419

  20. Monolithic multichannel ultraviolet detector arrays and continuous phase evolution in MgxZn1xO composition spreads

    E-print Network

    Rubloff, Gary W.

    whose potential device applications include UV lasers,1,2 transparent con- ducting films for solar cellsMonolithic multichannel ultraviolet detector arrays and continuous phase evolution in MgxZn1纗 the spread is used as a basis for compact broadband photodetector arrays with a range of detection

  1. A four-pixel single-photon pulse-position array fabricated from WSi superconducting nanowire single-photon detectors

    SciTech Connect

    Verma, V. B., E-mail: verma@nist.gov; Horansky, R.; Lita, A. E.; Mirin, R. P.; Nam, S. W. [National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305 (United States); Marsili, F.; Stern, J. A.; Shaw, M. D. [Jet Propulsion Laboratory, 4800 Oak Grove Dr., Pasadena, California 91109 (United States)

    2014-02-03

    We demonstrate a scalable readout scheme for an infrared single-photon pulse-position camera consisting of WSi superconducting nanowire single-photon detectors. For an N N array, only 2 N wires are required to obtain the position of a detection event. As a proof-of-principle, we show results from a 2 2 array.

  2. DETECTORS AND EXPERIMENTAL METHODS: Study of the characteristics of a scintillation array and single pixels for nuclear medicine imaging applications

    Microsoft Academic Search

    Jie Zhu; Hong-Guang Ma; Wen-Yan Ma; Hui Zeng; Zhao-Min Wang; Zi-Zong Xu

    2009-01-01

    By using a pixelized Nal(Tl) crystal array coupled to a R2486 PSPMT, the characteristics of the array and of a single pixel, such as the light output, energy resolution, peak-to-valley ratio (P\\/V) and imaging performance of the detector were studied. The pixel size of the NaI(TI) scintillation pixel array is 2 mm2 mm5 mm. There are in total 484 pixels

  3. Characterization of direct readout Si:Sb and Si:Ga infrared detector arrays for space-based astronomy

    Microsoft Academic Search

    Mark E. McKelvey; Craig R. McCreight; John H. Goebel; Nicolas N. Moss; Maureen L. Savage

    1988-01-01

    Preliminary test results from the evaluation of Si:Sb and Si:Ga 58 x 62-element infrared detector arrays are presented. These devices are being characterized under background conditions and readout rates representative of operation in orbiting, crogenically-cooled infrared observatories. The arrays are hybridized to silicon direct-readout multiplexers which allow random-access and nondestructive readout. Array performance optimization is being conducted with a flexible

  4. MEDEA: a multi element detector array for gamma ray and light charged particle detection at the LNS-Catania

    Microsoft Academic Search

    E. Migneco; C. Agodi; R. Alba; G. Bellia; R. Coniglione; A. del Zoppo; P. Finocchiaro; C. Maiolino; P. Piattelli; G. Raia; P. Sapienza

    1992-01-01

    A 4 pi highly granular Mutli Element DEtector Array (MEDEA) for gamma-rays and light charged particles is described. Its basic configuration consists of 180 barium fluoride scintillator crystals, arranged in the shape of a ball, plus a forward angle wall of 120 phoswich detectors. The inner radius of the ball (22 cm) and the distance of the wall from the

  5. A compact 64-pixel CsI(T1)/Si PIN photodiode imaging module with IC readout

    SciTech Connect

    Gruber, Gregory J.; Choong, Woon-Seng; Moses, William W.; Derenzo, Stephen E.; Holland, Stephen E.; Pedrali-Noy, Marzio; Krieger, Brad; Mandelli, Emanuele; Meddeler, Gerrit; Wang, Nadine W.

    2001-08-09

    We characterize the performance of a complete 64-pixel compact gamma camera imaging module consisting of optically isolated 3 mm 3 mm 5 mm CsI(Tl) crystals coupled to a custom array of low-noise Si PIN photodiodes read out by a custom IC. At 50 V bias the custom 64-pixel photodiode arrays demonstrate an average leakage current of 28 pA per 3 mm 3 mm pixel, a 98.5 percent yield of pixels with <100 pA leakage, and a quantum efficiency of about 80 percent for 540 nm CsI(Tl) scintillation photons. The custom 64-channel readout IC uses low-noise preamplifiers, shaper amplifiers, and a winner-take-all (WTA) multiplexer. The IC demonstrates maximum gain of 120 mV / 1000 e-, the ability to select the largest input signal in less than 150 ns, and low electronic noise at 8 ms peaking time ranging from 25 e- rms (unloaded) to an estimated 180 e- rms (photodiode load of 3 pF, 50 pA). At room temperature a complete 64-pixel detector module employing a custom photodiode array and readout IC demonstrates an average energy resolution of 23.4 percent fwhm and an intrinsic spatial resolution of 3.3 mm fwhm for the 140 keV emissions of 99mTc. Construction of an array of such imaging modules is straightforward, hence this technology shows strong potential for numerous compact gamma camera applications, including scintimammography.

  6. Three-dimensional modeling and inversion of x-ray pinhole detector arrays

    SciTech Connect

    Tritz, K.; Stutman, D.; Delgado-Aparicio, L.; Finkenthal, M. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218 (United States)

    2006-10-15

    X-ray pinhole detectors are a common and useful diagnostic for high temperature and fusion-grade plasmas. While the measurements from such diagnostics are line integrated, local emission can be recovered by inverting or modeling the data using varying assumptions including toroidal symmetry, flux surface isoemissivity, and one-dimensional (1D) chordal lines of sight. This last assumption is often valid when the structure sizes and gradient scale lengths of interest are much larger than the spatial resolution of the detector elements. However, x-ray measurements of, for example, the strong gradients in the H-mode pedestal may require a full three-dimensional (3D) treatment of the detector geometry when the emission of the plasma has a significant variation within the field of view, especially in a high-triangularity, low aspect ratio plasma. Modeling of a high spatial resolution tangential edge array for NSTX has shown that a proper 3D treatment can improve the effective spatial resolution of the detector by 10%-40% depending on the modeled signal-to-noise ratio and gradient scale length. Results from a general treatment of arbitrary detector geometry will provide a guideline for the amount of systematic error that can be expected by a 1D versus 3D field of view analysis.

  7. Soft x-ray array system with variable filters for the DIII-D tokamak

    SciTech Connect

    Hollmann, E. M.; Chousal, L.; Hernandez, R. [University of California, San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417 (United States); Fisher, R. K.; Jackson, G. L.; Pidcoe, S. V.; Taussig, D. A. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); Lanctot, M. J. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94550 (United States); Shankara, J. [Institute for Plasma Research, Bhat, Gandhinagar (India)

    2011-11-15

    Recent upgrades to the soft x-ray (SXR) array system on the DIII-D tokamak are described. The system consists of two 32-channel arrays at one toroidal location and three toroidally distributed 12-channel arrays. The 32-channel arrays have been completely rebuilt to allow the switching of SXR filters without breaking vacuum. The 12-channel arrays have had upgrades performed to detectors, view slits, and data acquisition. Absolute extreme ultraviolet (AXUV) photodiodes are used as detectors in all arrays, allowing detection of photons ranging in energy from 2 eV to 10 keV. In the fixed-filter arrays, 127 {mu}m Be filters are used. In the variable-filter arrays, filter wheels are used to switch between five different possible pinhole/filter combinations.

  8. Soft x-ray array system with variable filters for the DIII-D tokamak

    NASA Astrophysics Data System (ADS)

    Hollmann, E. M.; Chousal, L.; Fisher, R. K.; Hernandez, R.; Jackson, G. L.; Lanctot, M. J.; Pidcoe, S. V.; Shankara, J.; Taussig, D. A.

    2011-11-01

    Recent upgrades to the soft x-ray (SXR) array system on the DIII-D tokamak are described. The system consists of two 32-channel arrays at one toroidal location and three toroidally distributed 12-channel arrays. The 32-channel arrays have been completely rebuilt to allow the switching of SXR filters without breaking vacuum. The 12-channel arrays have had upgrades performed to detectors, view slits, and data acquisition. Absolute extreme ultraviolet (AXUV) photodiodes are used as detectors in all arrays, allowing detection of photons ranging in energy from 2 eV to 10 keV. In the fixed-filter arrays, 127 ?m Be filters are used. In the variable-filter arrays, filter wheels are used to switch between five different possible pinhole/filter combinations.

  9. Array detector for high energy laser based on diffuse transmission sampling

    SciTech Connect

    Pang, Miao [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China) [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang, 621900 China (China); Key Laboratory of High Energy Laser, CAEP, Mianyang 621900 (China); Rong, Jian [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China)] [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Zhou, Shan; Wu, Juan; Zhang, Wei; Hu, Xiaoyang [Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang, 621900 China (China)] [Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang, 621900 China (China); Fan, Guobin [Key Laboratory of High Energy Laser, CAEP, Mianyang 621900 (China)] [Key Laboratory of High Energy Laser, CAEP, Mianyang 621900 (China)

    2014-01-15

    In order to improve the ability and accuracy of measuring the temporal杝patial distribution of the intensity of a large-size, high-energy laser beam, a novel array detecting method based on diffuse transmission sampling is proposed. The measurement principle and the design of the sampling and attenuating unit are presented. High-temperature-resistant diffuse transmission material is used to sample and attenuate a high energy laser beam. Pure copper, whose surface is first sand-blasted and then gold-plated, is applied to scatter the incident high-energy laser beam. The formula for the attenuation ratio was derived in detail. We developed two large-aperture array detectors with spatial resolution of 5 mm, spatial duty ratio of 20%, and useable angle range of 30 without varying the responsivity, the non-uniformity in the laser profile measurement is below 1%, and the repeatability error in the laser power measurement is approximately 1%. The maximal energy density that the array detector can endure is more than 10 kJ/cm{sup 2}.

  10. Development of an ultra-low-power x-ray-photon-resolving imaging detector array

    NASA Astrophysics Data System (ADS)

    Sun, Shunming; Downey, Stephen; Gaalema, Stephen; Gates, James L.; Jernigan, J. Garrett; Kaaret, Philip; MacIntosh, Scott; Ramsey, Brian; Wall, Bruce

    2010-08-01

    We report on progress to develop and demonstrate CZT and Si hybrid detector arrays for future NASA missions in X-ray and Gamma-ray astronomy. The primary goal for these detectors is consistent with the design concept for the EXIST mission1 and will also be appropriate for other NASA applications and ground-based projects. In particular we target science instruments that have large aperture (multiple square meters) and therefore require a low power ROIC (readout integrated circuits) design (< 10 microwatt per pixel in quiescent mode). The design also must achieve good energy resolution for single photon detection for X rays in the range 5-600 keV with a CZT sense layer and 2-30 keV with a Si sense layer. The target CZT arrays are 2 cm 2 cm with 600 micron square-shaped pixels. The low power smart pixel detects rare X-ray hits with an adjustable threshold setting. A test array of 7 5 pixels with a 5 mm thick CZT sense layer demonstrates that the low power pixel can successfully detect X-rays with {50 readout noise electrons RMS.

  11. Pixel array detector for time-resolved x-ray scattering

    SciTech Connect

    Rodricks, B.G. [Experimental Facilities Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States)] [Experimental Facilities Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Barna, S.L.; Gruner, S.M.; Shepherd, J.A.; Tate, M.W.; Wixted, R.L. [Department of Physics, Princeton University, Princeton, NJ 08544 (United States)] [Department of Physics, Princeton University, Princeton, NJ 08544 (United States)

    1996-09-01

    This paper describes the development of a large area hybrid pixel detector designed for time-resolved synchrotron x-ray scattering experiments in which limited frames, with a high framing rate, are required. The final design parameters call for a 1024{times}1024 pixel array device with 150-micron pixels that is 100{percent} quantum efficient for x-rays with energy up to 20 keV, with a framing rate in the microsecond range. The device will consist of a fully depleted diode array bump bonded to a CMOS electronic storage capacitor array with eight frames per pixel. The two devices may be separated by a x-ray blocking layer that protects the radiation-sensitive electronics layer from damage. The signal is integrated in the electronics layer and stored in one of eight CMOS capacitors. After eight frames are taken, the data are then read out, using clocking electronics external to the detector, and stored in a RAM disk. Results will be presented on the development of a prototype 4{times}4 pixel electronics layer that is capable of storing at least 10,000 12-keV x-ray photons for a capacity of over 50 million electrons with a noise corresponding to 2 x-ray photons per pixel. The diode detective layer and electronics storage layer along with the radiation damage and blocking layers will be discussed. {copyright} {ital 1996 American Institute of Physics.}

  12. Prototype detector for 6keV x-rays using nine series arrays of tunnel junctions

    Microsoft Academic Search

    William C. Barber; Roger W. Bland; Robert T. Johnson; Kenneth E. Laws; Julie S. Lee; Simon E. Labov; Carl A. Mears

    1994-01-01

    We have fabricated a device consisting of nine arrays of series- connected superconducting aluminum tunnel junctions on a thin sapphire substrate, as a detector of 6-keV X-rays. Tunnel junctions are of interest as particle detectors because their theoretical minimum excitation energy is on the order of one milli-electron volt, a factor of one thousand lower than conventional semiconductor detectors. We

  13. Pixel array detector for X-ray free electron laser experiments

    NASA Astrophysics Data System (ADS)

    Philipp, Hugh T.; Hromalik, Marianne; Tate, Mark; Koerner, Lucas; Gruner, Sol M.

    2011-09-01

    X-ray free electron lasers (XFELs) promise to revolutionize X-ray science with extremely high peak brilliances and femtosecond X-ray pulses. This will require novel detectors to fully realize the potential of these new sources. There are many current detector development projects aimed at the many challenges of meeting the XFEL requirements [1,2]. This paper describes a pixel array detector (PAD) that has been developed for the Coherent X-ray Imaging experiment at the Linac Coherent Light Source (LCLS) at the SLAC National Laboratory [3]. The detector features 14-bit in-pixel digitization; a 2-level in-pixel gain setting that can be used to make an arbitrary 2-D gain pattern that is adaptable to a particular experiment; the ability to handle instantaneous X-ray flux rates of 10 17 photons per second; and continuous frames rates in excess of 120 Hz. The detector uses direct detection of X-rays in a silicon diode. The charge produced by the diode is integrated in a pixilated application specific integrated circuit (ASIC) which digitizes collected holes with single X-ray photon capability. Each ASIC is 194185 pixels, each pixel is 110 ?m110 ?m on a side. Each pixel can detect up to 2500 X-rays per frame in low-gain mode, yet easily detects single photons at high-gain. Cooled, single-chip detectors have been built and meet all the required specifications. SLAC National Laboratory is engaged in constructing a tiled, multi-chip 15161516 pixel detector.

  14. 1024 1024 Si:As IBC detector arrays for JWST MIRI

    NASA Astrophysics Data System (ADS)

    Love, Peter J.; Hoffman, Alan W.; Lum, Nancy A.; Ando, Ken J.; Rosbeck, Joe; Ritchie, William D.; Therrien, Neil J.; Holcombe, Roger S.; Corrales, Elizabeth

    2005-08-01

    1K 1K Si:As Impurity Band Conduction (IBC) arrays have been developed by RVS for the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI). MIRI provides imaging, coronagraphy, and low and medium resolution spectroscopy over the 5 - 28 ?m band. The IBC devices are also suitable for other low-background applications. The Si:As IBC detectors have a pixel dimension of 25 ?m and respond to infrared radiation between 5 and 28 ?m, covering an important Mid-IR region beyond the 1 - 5 ?m range covered by the JWST NIRCam and NIRSpec instruments. Due to high terrestrial backgrounds at the longer Mid-IR wavelengths, it is very difficult to conduct ground-based observations at these wavelengths. Hence, the MIRI instrument on JWST can provide science not obtainable from the ground. We describe results of the development of a new 1024 1024 Si:As IBC array that responds with high quantum efficiency over the wavelength range 5 to 28 ?m. The previous generation's largest, most sensitive infrared (IR) detectors at these wavelengths were the 256 256 / 30 ?m pitch Si:As IBC devices built by Raytheon for the SIRTF/IRAC instrument1. Detector performance results will be discussed, including relative spectral response, Responsive Quantum Efficiency (RQE) vs. detector bias, and dark current versus temperature. In addition, Sensor Chip Assembly (SCA) data will be presented from the first Engineering SCAs. The detector ROIC utilizes a PMOS Source Follower per Detector (SFD) input circuit with a well capacity of about 2 105 electrons. The read noise of the "bare" MUX is less than 12 e- rms with Fowler-8 sampling at an operating temperature of 7 K. A companion paper by Craig McMurtry (University of Rochester) will discuss the details of SB305 MUX noise measurements2. Other features of the IBC array include 4 video outputs and a separate reference output with a frame rate of 0.36 Hz (2.75 sec frame time). Power dissipation is about 0.5 mW at a 0.36 Hz frame rate. Reset modes include both global reset and reset by row (ripple mode). Reference pixels are built-in to the output data stream. The 1K 1K IBC is packaged in a robust modular package that consists of a multilayer motherboard, SiC pedestal, and cable assembly with 51-pin MDM connector. All materials of construction were chosen to match the thermal expansion coefficient of Silicon to provide excellent module thermal cycle reliability for cycling between room temperature and 7 K.

  15. A new detector for mass spectrometry: Direct detection of low energy ions using a multi-pixel photon counter

    SciTech Connect

    Wilman, Edward S.; Gardiner, Sara H.; Vallance, Claire [Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Rd, Oxford OX1 3TA (United Kingdom); Nomerotski, Andrei [Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Rd, Oxford OX1 3RH (United Kingdom); Turchetta, Renato [Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom); Brouard, Mark [Department of Chemistry, University of Oxford, Physical and Theoretical Chemistry Laboratory, South Parks Rd, Oxford OX1 3QZ (United Kingdom)

    2012-01-15

    A new type of ion detector for mass spectrometry and general detection of low energy ions is presented. The detector consists of a scintillator optically coupled to a single-photon avalanche photodiode (SPAD) array. A prototype sensor has been constructed from a LYSO (Lu{sub 1.8}Y{sub 0.2}SiO{sub 5}(Ce)) scintillator crystal coupled to a commercial SPAD array detector. As proof of concept, the detector is used to record the time-of-flight mass spectra of butanone and carbon disulphide, and the dependence of detection sensitivity on the ion kinetic energy is characterised.

  16. Array-based carbon black-polymer composite vapor detectors for detection of DNT in environments containing complex analyte mixtures

    NASA Astrophysics Data System (ADS)

    Briglin, Shawn M.; Freund, Michael S.; Sisk, Brian C.; Lewis, Nathan S.

    2001-10-01

    Thin films of carbon black-organic polymer composites have been deposited across two metallic leads, with sorption of vapors producing swelling-induced resistance changes of the detector films. To identify and classify vapors, arrays of such vapor sensing elements have been constructed in which each element of the array contains a different polymer as the insulating phase and a common conductor, carbon black, as the conducting phase. The differing gas-solid partition coefficients for the various polymers of the detector array produce a pattern of differential resistance changes that is used to classify vapors and vapor mixtures. The performance of this detector array system towards 2,4-dinitrotoluene, the predominant signature in the vapor phase above land mines, in the presence high concentrations of water or of acetone has been evaluated.

  17. An aging study of the signal and noise characteristics in large-area CMOS detectors

    Microsoft Academic Search

    Jong Chul Han; Seungman Yun; Chang Hwy Lim; Tae Gyun Youm; Sung Kyn Heo; Tae Woo Kim; Ian Cunningham; Ho Kyung Kim

    2010-01-01

    For a detector consisting of a phosphor screen and a photodiode array made by complementary metal-oxidesemiconductor (CMOS) process, we have experimentally re-investigated the long-term stability of the signal and noise characteristics as a function of the accumulated dose at the entrance surface of the detector in addition to the previous study [IEEE Trans. Nucl. Sci. 56(3) 1121 (2009)]. The irradiation

  18. Observation of high energy atmospheric neutrinos with antarctic muon and neutrino detector array

    SciTech Connect

    Ahrens, J.; Andres, E.; Bai, X.; Barouch, G.; Barwick, S.W.; Bay, R.C.; Becka, T.; Becker, K.-H.; Bertrand, D.; Binon, F.; Biron, A.; Booth, J.; Botner, O.; Bouchta, A.; Bouhali, O.; Boyce, M.M.; Carius, S.; Chen, A.; Chirkin, D.; Conrad, J.; Cooley, J.; Costa, C.G.S.; Cowen, D.F.; Dalberg, E.; De Clercq, C.; DeYoung, T.; Desiati, P.; Dewulf, J.-P.; Doksus, P.; Edsjo, J.; Ekstrom, P.; Feser, T.; Frere, J.-M.; Gaisser, T.K.; Gaug, M.; Goldschmidt, A.; Hallgren, A.; Halzen, F.; Hanson, K.; Hardtke, R.; Hauschildt, T.; Hellwig, M.; Heukenkamp, H.; Hill, G.C.; Hulth, P.O.; Hundertmark, S.; Jacobsen, J.; Karle, A.; Kim, J.; Koci, B.; Kopke, L.; Kowalski, M.; Lamoureux, J.I.; Leich, H.; Leuthold, M.; Lindahl, P.; Liubarsky, I.; Loaiza, P.; Lowder, D.M.; Madsen, J.; Marciniewski, P.; Matis, H.S.; McParland, C.P.; Miller, T.C.; Minaeva, Y.; Miocinovic, P.; Mock, P.C.; Morse, R.; Neunhoffer, T.; Niessen, P.; Nygren, D.R.; Ogelman, H.; Olbrechts, Ph.; Perez de los Heros, C.; Pohl, A.C.; Porrata, R.; Price, P.B.; Przybylski, G.T.; Rawlins, K.; Reed, C.; Rhode, W.; Ribordy, M.; Richter, S.; Rodriguez Martino, J.; Romenesko, P.; Ross, D.; Sander, H.-G.; Schmidt, T.; Schneider, D.; Schwarz, R.; Silvestri, A.; Solarz, M.; Spiczak, G.M.; Spiering, C.; Starinsky, N.; Steele, D.; Steffen, P.; Stokstad, R.G.; Streicher, O.; Sudhoff, P.; Sulanke, K.-H.; Taboada, I.; Thollander, L.; Thon, T.; Tilav, S.; Vander Donckt, M.; Walck, C.; Weinheimer, C.; Wiebusch, C.H.; Wiedeman, C.; Wischnewski, R.; Wissing, H.; Woschnagg, K.; Wu, W.; Yodh, G.; Young, S.

    2002-05-07

    The Antarctic Muon and Neutrino Detector Array (AMANDA) began collecting data with ten strings in 1997. Results from the first year of operation are presented. Neutrinos coming through the Earth from the Northern Hemisphere are identified by secondary muons moving upward through the array. Cosmic rays in the atmosphere generate a background of downward moving muons, which are about 10{sup 6} times more abundant than the upward moving muons. Over 130 days of exposure, we observed a total of about 300 neutrino events. In the same period, a background of 1.05 x 10{sup 9} cosmic ray muon events was recorded. The observed neutrino flux is consistent with atmospheric neutrino predictions. Monte Carlo simulations indicate that 90 percent of these events lie in the energy range 66 GeV to 3.4 TeV. The observation of atmospheric neutrinos consistent with expectations establishes AMANDA-B10 as a working neutrino telescope.

  19. Micro Cantilever Movement Detection with an Amorphous Silicon Array of Position Sensitive Detectors

    PubMed Central

    Contreras, Javier; Costa, Daniel; Pereira, Sonia; Fortunato, Elvira; Martins, Rodrigo; Wierzbicki, Rafal; Heerlein, Holger; Ferreira, Isabel

    2010-01-01

    The movement of a micro cantilever was detected via a self constructed portable data acquisition prototype system which integrates a linear array of 32 1D amorphous silicon position sensitive detectors (PSD). The system was mounted on a microscope using a metal structure platform and the movement of the 30 ?m wide by 400 ?m long cantilever was tracked by analyzing the signals acquired by the 32 sensor array electronic readout system and the relevant data algorithm. The obtained results show a linear behavior of the photocurrent relating X and Y movement, with a non-linearity of about 3%, a spatial resolution of less than 2 ?m along the lateral dimension of the sensor as well as of less than 3 ?m along the perpendicular dimension of the sensor, when detecting just the micro-cantilever, and a spatial resolution of less than 1 ?m when detecting the holding structure. PMID:22163648

  20. DENSITY: software for analysing capture-recapture data from passive detector arrays

    USGS Publications Warehouse

    Efford, M.G.; Dawson, D.K.; Robbins, C.S.

    2004-01-01

    A general computer-intensive method is described for fitting spatial detection functions to capture-recapture data from arrays of passive detectors such as live traps and mist nets. The method is used to estimate the population density of 10 species of breeding birds sampled by mist-netting in deciduous forest at Patuxent Research Refuge, Laurel, Maryland, U.S.A., from 1961 to 1972. Total density (9.9 ? 0.6 ha-1 mean ? SE) appeared to decline over time (slope -0.41 ? 0.15 ha-1y-1). The mean precision of annual estimates for all 10 species pooled was acceptable (CV(D) = 14%). Spatial analysis of closed-population capture-recapture data highlighted deficiencies in non-spatial methodologies. For example, effective trapping area cannot be assumed constant when detection probability is variable. Simulation may be used to evaluate alternative designs for mist net arrays where density estimation is a study goal.

  1. Using a germanium detector array to mimic double-beta decays to excited states

    NASA Astrophysics Data System (ADS)

    Kazkaz, Kareem

    2005-04-01

    In the wake of neutrino oscillation experiments verifying that neutrinos have mass, there has been a lot of interest in ^76Ge double-beta decay. Double-beta decays can proceed either to the ground state or an excited state of the daughter nucleus. The ratios of the rates of these decay modes can give guidance to determining the underlying structure of nuclear matrix elements. The rates of these decays, however, are very small, so for the purpose of developing analysis toolkits for the Majorana Experiment it helps to create similar signals with rates useable in a non-low-background environment. We present methods of using a segmented natural germanium detector to mimic the signature of double-beta decay to an excited state, along with preliminary analysis of these signals from an above ground detector array.

  2. Mosaic wedge-and-strip arrays for large format microchannel plate detectors

    NASA Technical Reports Server (NTRS)

    Martin, Christopher; Rasmussen, Andrew

    1989-01-01

    The authors present a novel method for joining wedge-and-strip patterns on single anodes in a mosaic array. With only a modest increase in complexity over three-conductor anodes currently in use, the ultimate detector position resolution can be significantly improved, and large-format microchannel plate detectors with pore-size-limited resolution are made possible. The problem of the transition from one anode to the next has been solved with a novel linear encoding scheme, which exhibits essentially distortionless behavior at boundaries parallel to the conducting elements and only slight distortion at the orthogonal boundaries. The ultimate resolution for two anode designs, one designed for large-format imaging and the other for high-resolution spectroscopy, is also predicted.

  3. Short range laser obstacle detector. [for surface vehicles using laser diode array

    NASA Technical Reports Server (NTRS)

    Kuriger, W. L. (inventor)

    1973-01-01

    A short range obstacle detector for surface vehicles is described which utilizes an array of laser diodes. The diodes operate one at a time, with one diode for each adjacent azimuth sector. A vibrating mirror a short distance above the surface provides continuous scanning in elevation for all azimuth sectors. A diode laser is synchronized with the vibrating mirror to enable one diode laser to be fired, by pulses from a clock pulse source, a number of times during each elevation scan cycle. The time for a given pulse of light to be reflected from an obstacle and received is detected as a measure of range to the obstacle.

  4. Developing Neutron Detector Array VANDLE for Nucleosynthesis Studies in X-Ray Bursts and Supernova Explosions

    NASA Astrophysics Data System (ADS)

    Spassova, Irena; Cizewski, J. A.; Peters, W. A.; Matei, C.; Blackmon, J. C.

    2010-01-01

    The Versatile Array of Neutron Detectors at Low Energy (VANDLE) is being developed to study the properties of unstable atomic nuclei via (d,n) reactions and beta delayed neutron emission. The (d,n) reactions, on unstable nuclei such as 56Ni, are of great interest in understanding the synthesis of heavy proton-rich nuclei in X-ray bursts and Supernova explosions. This doubly-magic nucleus is thought to be an important link in the production of heavy elements and a waiting point in the rp-process, which typically occurs in these explosive environments. The VANDLE array will be comprised of individual scintillator bars of two set lengths: 2 m and 60 cm, coupled to photomultiplier tubes (PMTs). It will allow us to study the 2H(56Ni,n)57Cu reaction cross section, and allow us to calculate the reaction rate for the 56Ni(p,?)57Cu reaction. The prototypes for these bars are undergoing testing. The attenuation length of the scintillator bar plays a direct role in the detector efficiency, while the position and timing calibrations help pinpoint where an event occurred in the bar. By using different configurations and sources, it was possible to measure the attenuation length and the position and timing resolutions. Experiments have also been performed pertaining to the materials used in coupling the scintillator to the PMT. All these tests will help optimize the performance of the detectors. The experimental results for the prototype detectors will be presented. This work was supported in part by the U.S. Department of Energy and National Science Foundation.

  5. Far Field Monitoring of Rogue Nuclear Activity with an Array of Large anti-neutrino Detectors

    E-print Network

    Eugene Guillian

    2006-09-27

    The result of a study on the use of an array of large anti-neutrino detectors for the purpose of monitoring rogue nuclear activity is presented. Targeted regional monitoring of a nation bordering large bodies of water with no pre-existing legal nuclear activity may be possible at a cost of about several billion dollars, assuming several as-yet-untested schemes pan out in the next two decades. These are: (1) the enabling of a water-based detector to detect reactor anti-neutrinos by doping with GdCl$_3$; (2) the deployment of a KamLAND-like detector in a deep-sea environment; and (3) the scaling of a Super-Kamiokande-like detector to a size of one or more megatons. The first may well prove feasible, and should be tested by phase-III Super-Kamiokande in the next few years. The second is more of a challenge, but may well be tested by the Hanohano collaboration in the coming decade. The third is perhaps the least certain, with no schedule for construction of any such device in the foreseeable future. In addition to the regional monitoring scheme, several global, untargeted monitoring schemes were considered. All schemes were found to fail benchmark sensitivity levels by a wide margin, and to cost at least several trillion dollars.

  6. Array of HgI2 detectors on the HL-1M Tokamak

    NASA Astrophysics Data System (ADS)

    Jinwei, Yang; Wei, Zhang; Shiqing, Wang

    2004-08-01

    An array of seven HgI2 detectors, which are suitable for detecting the time and space evolution of the x-ray radiation flux and energy spectrum in the range between 15-150 keV relevant to suprathermal electron and runaway electrons was installed on the HL-1M Tokamak (R0=1.02 m, a=0.26 m, BT=3.5 T, IP=350 kA, ne=3-61013 cm-3, Te=0.8-1.5 keV). Our iodine mercury (HgI2) semiconductor detectors possess the properties of low noise level, high detection efficiency, high counting rate, high energy resolution, and working at room temperature. Every detector is a high quality, high purity detector cut out of a big size HgI2 crystal. A new type of multichannel energy spectrometer with a high speed acquisition system was developed. Therefore, the spatial and temporal distribution of the x-ray energy spectrum induced by thermal and superthermal electrons can be observed.

  7. Performance of common-grid pixelated CZT detector with different array geometries

    NASA Astrophysics Data System (ADS)

    Yang, G.; Xiao, S.; Ma, Y.; Zhang, L.

    2015-06-01

    A 4 4 common-grid pixelated CZT detector with four different array geometries has been designed and fabricated. The impact of small pixel effect, guide effect of the steering grid and edge effect on detector performance has been investigated. Both the weighting potential and the real electric field distributions have been calculated for better understanding the charge induction and collection. Results show that with constant pixel pitch, smaller anode pixel suffers from serious charge loss in volume and surface layer between anode pixels and steering grid. The small pixel effect is not strong enough to remove hole trailing for lager anode pixel. A relative high potential difference between anode pixels and steering grid leads to sufficient charge collection resulting in a better detector performance, especially for smaller anode pixels. In addition to edge and corner effects due to faulty or imperfect fabrication of the detector, the weighting potential distribution difference is an inherent physical effect that alter the profile of the induced signals in edge and corner pixels.

  8. THE COSMIC-RAY ENERGY SPECTRUM OBSERVED WITH THE SURFACE DETECTOR OF THE TELESCOPE ARRAY EXPERIMENT

    SciTech Connect

    Abu-Zayyad, T.; Allen, M.; Anderson, R.; Barcikowski, E.; Belz, J. W.; Bergman, D. R.; Blake, S. A.; Cady, R.; Hanlon, W. [High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah (United States); Aida, R. [University of Yamanashi, Interdisciplinary Graduate School of Medicine and Engineering, Kofu, Yamanashi (Japan); Azuma, R.; Fukuda, T. [Graduate School of Science and Engineering, Tokyo Institute of Technology, Meguro, Tokyo (Japan); Cheon, B. G.; Cho, E. J. [Department of Physics and Research Institute of Natural Science, Hanyang University, Seongdong-gu, Seoul (Korea, Republic of); Chiba, J. [Department of Physics, Tokyo University of Science, Noda, Chiba (Japan); Chikawa, M. [Department of Physics, Kinki University, Higashi Osaka, Osaka (Japan); Cho, W. R. [Department of Physics, Yonsei University, Seodaemun-gu, Seoul (Korea, Republic of); Fujii, H. [Institute of Particle and Nuclear Studies, KEK, Tsukuba, Ibaraki (Japan); Fujii, T. [Graduate School of Science, Osaka City University, Osaka, Osaka (Japan); Fukushima, M. [Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba (Japan); and others

    2013-05-01

    The Telescope Array (TA) collaboration has measured the energy spectrum of ultra-high energy cosmic rays (UHECRs) with primary energies above 1.6 Multiplication-Sign 10{sup 18} eV. This measurement is based upon four years of observation by the surface detector component of TA. The spectrum shows a dip at an energy of 4.6 Multiplication-Sign 10{sup 18} eV and a steepening at 5.4 Multiplication-Sign 10{sup 19} eV which is consistent with the expectation from the GZK cutoff. We present the results of a technique, new to the analysis of UHECR surface detector data, that involves generating a complete simulation of UHECRs striking the TA surface detector. The procedure starts with shower simulations using the CORSIKA Monte Carlo program where we have solved the problems caused by use of the ''thinning'' approximation. This simulation method allows us to make an accurate calculation of the acceptance of the detector for the energies concerned.

  9. A study of vacuum-ultraviolet stability of silicon photodiodes

    NASA Astrophysics Data System (ADS)

    Zabrodsky, V. V.; Belik, V. P.; Aruev, P. N.; Ber, B. Ya.; Bobashev, S. V.; Petrenko, M. V.; Sukhanov, V. L.

    2012-09-01

    Silicon photodiodes have been tested for resistance to vacuum-ultraviolet radiation at 121.6 nm. The responsivities of the p- n and n- p photodiodes under study were found to degrade by tens of percent at a VUV radiation dose on the order of tens of mJ/cm2. The effect of reversible photocurrent relaxation has been observed in detectors based on n- p structures.

  10. Response of a photodiode coupled with boron for neutron detection

    NASA Astrophysics Data System (ADS)

    Kang, K. H.; Jeon, H. B.; Kim, G. N.; Park, H.; Hyun, H. J.; Kah, D. H.

    2014-11-01

    We have studied a silicon semiconductor detector as an alternative to commercial 3He-gas-based neutron detectors. In this paper, we present a measurement of the energy spectrum of neutron-induced secondary radiation by using a silicon detector. Polyethylene was used to produce thermal neutrons by using a 252Cf radioactive source. The photodiode was then irradiated by thermal neutrons, followed by a 10B converter that produced charged particles. This configuration was found to have a better response to neutrons than a moderator-converter-photodiode configuration. By comparing the measurements with Geant4 simulations, the air gap between the photodiode and the converter was determined to be 0.3 mm and the detector response of the semiconductor device was found to be a smeared Gaussian function with ? = 0.1.

  11. Development of novel on-chip, customer-design spiral biasing adaptor on for Si drift detectors and detector arrays for X-ray and nuclear physics experiments

    NASA Astrophysics Data System (ADS)

    Li, Zheng; Chen, Wei

    2014-11-01

    A novel on-chip, customer-design spiral biasing adaptor (SBA) has been developed. A single SBA is used for biasing a Si drift detector (SDD) and SDD array. The use of an SBA reduces the biasing current. This paper shows the calculation of the geometry of an SBA and an SDD to get the best drift field in the SDD and SDD array. Prototype SBAs have been fabricated to verify the concept. Electrical measurements on these SBAs are in agreement with the expectations. The new SDD array with an SBA can be used for X-ray detection and in nuclear physics experiments.

  12. Three-dimensional modeling and simulation of large-format hybrid indium antimonide detector arrays

    NASA Astrophysics Data System (ADS)

    Zhang, Li-Wen; Shao, Ming; Zhang, Xiao-Ling; Meng, Qing-Duan; Wang, Jin-Chan; Lv, Yan-Qiu

    2013-10-01

    Infrared sensors, such as indium antimonide (InSb) detectors, are generally required to be cooled to 77 K in operation. High fracture probability under thermal shock, especially in large InSb infrared focal plane arrays (IRFPAs), limits their applicability. It is necessary to establish a realistic three-dimensional (3-D) structural model of large-format InSb IRFPAs. However, few data are available on 3-D high-fidelity structural modeling and simulation of large IRFPAs due to their complicated structure and huge meshing numbers. A simple equivalent modeling method had been used in our early works, which could reduce meshing numbers, but did not consider the complicated structure, and also brought a new problem that the equivalent outer region of the model was not consistent with the actual IRFPAs. To solve the problems, an improved equivalent modeling method is proposed, where a small-format array is first split into two parts and then employed to equivalently replace the real large-format array. A 3-D high-fidelity structural model of large-format hybrid InSb IRFPAs is developed; here, a 3232 array is adopted to replace the real 128128 array. The results show that the simulated stress and strain distribution characteristics of InSb chip are well in agreement with the fracture photograph of actual 128128 InSb IRFPAs in testing, verifying the validity and feasibility of the 3-D structural model of large-format IRFPAs. All these are beneficial to further explore fracture mechanisms and improve the reliability of large-format hybrid InSb IRFPAs.

  13. Growth of ZnO Nanowire Arrays for Advanced Ultraviolet Detectors

    NASA Astrophysics Data System (ADS)

    Zeller, John; Manzur, Tariq; Anwar, A. F. Mehdi; Sood, Ashok K.

    2012-02-01

    Zinc oxide (ZnO) provides a unique wide bandgap biocompatible material system exhibiting both semiconducting and piezoelectric properties. Bulk ZnO has a bandgap of 3.37 eV that corresponds to emissions in the solar blind ultraviolet (UV) spectral band (240-280 nm). We have grown highly ordered vertical arrays of ZnO nanowires using the metal organic chemical vapor deposition (MOCVD) technique on Si, silicon dioxide, c-plane sapphire, and GaN epitaxial substrates. UV detectors based on ZnO nanowires offer the highest UV sensitivity and lowest visible sensitivity for applications such as missile plume detection and threat warning. The development of UV detectors based on vertical nanowire arrays requires an innovative fabrication approach involving precise deposition of metal contacts, where UV sensor performance depends to a large extent on the growth conditions as well as on the substrate used. We will present experimental results on the structural, electrical, and optical properties of ZnO nanowires grown for UV sensing applications.

  14. Performance analysis of MIMO FSO systems with radial array beams and finite sized detectors

    NASA Astrophysics Data System (ADS)

    G鰇鏴, Muhsin C.; Kamac?o?lu, Canan; Uysal, Murat; Baykal, Yahya

    2014-10-01

    Multiple-input multiple-output (MIMO) systems are employed in free space optical (FSO) links to mitigate the degrading effects of atmospheric turbulence. In this paper, we consider a MIMO FSO system with practical transmitter and receiver configurations that consists of a radial laser array with Gaussian beams and finite sized detectors. We formulate the average received intensity and the power scinitillation as a function of the receiver coordinates in the presence of weak atmospheric turbulence by using the extended Huygens-Fresnel principle. Then, integrations over the finite sized multiple detectors are performed and the effect of the receiver aperture averaging is quantified. We further derive an outage probability expression of this MIMO system in the presence of turbulence-induced fading channels. Using the derived expressions, we demonstrate the effect of several practical system parameters such as the ring radius, the number of array beamlets, the source size, the link length, structure constant and the receiver aperture radius on the system performance.

  15. Far infrared thermal detectors for laser radiometry using a carbon nanotube array.

    PubMed

    Lehman, John H; Lee, Bob; Grossman, Erich N

    2011-07-20

    We present a description of a 1.5 mm long, vertically aligned carbon nanotube array (VANTA) on a thermopile and separately on a pyroelectric detector. Three VANTA samples, having average lengths of 40 ?m, 150 ?m, and 1.5 mm were evaluated with respect to reflectance at a laser wavelength of 394 ?m(760 GHz), and we found that the reflectance decreases substantially with increasing tube length, ranging from 0.38 to 0.23 to 0.01, respectively. The responsivity of the thermopile by electrical heating (98.4 mA/W) was equal to that by optical heating (98.0 mA/W) within the uncertainty of the measurement. We analyzed the frequency response and temporal response and found a thermal decay period of 500 ms, which is consistent with the specific heat of comparable VANTAs in the literature. The extremely low (0.01) reflectance of the 1.5 mm VANTAs and the fact that the array is readily transferable to the detector's surface is, to our knowledge, unprecedented. PMID:21772397

  16. Avalanche photodiode detection statistics for direct detection laser radar

    Microsoft Academic Search

    Douglas G. Youmans

    1992-01-01

    The detection statistics of avalanche photodiode detectors when used in laser radar systems are examined. In the laser radar systems considered here, a diffuse hard target is illuminated by a transmitted laser beam and the photons subtended by the receiving aperture and focused onto the detector obey negative-binomial statistics. The specific negative-binomial distribution is determined by the coherence length of

  17. Evaluation of bismuth germanate detectors

    SciTech Connect

    Swinth, K.L.; Eschbach, P.A.

    1993-12-01

    During International Atomic Energy Agency (IAEA) safeguards inspections, one of the activities is the verification of materials in the inventory through quantitative or qualitative measurements. Performance of these measurements requires an array of sophisticated detectors, electronics, shields, and stands. This requires the transport and handling of delicate systems that are both heavy and bulky. The increasing sophistication and miniaturization of electronic and computer systems have led to progressive reductions in both the weight and the bulk of such electronics. However, to take full advantage of these improvements, similar reductions must also occur in the size and weight of the detectors. The purpose of this study was to explore the usefulness of one type of new detector, the bismuth germinate (BGO) scintillator. The purpose was to test detectors for their performance at high (fission products) and low ({sup 235}U) photon energies. Information is also provided on other scintillators, including those using photodiode-coupled cesium iodide and germanium orthosilicate.

  18. Dosimetric performance and array assessment of plastic scintillation detectors for stereotactic radiosurgery quality assurance

    SciTech Connect

    Gagnon, Jean-Christophe; Theriault, Dany; Guillot, Mathieu; Archambault, Louis; Beddar, Sam; Gingras, Luc; Beaulieu, Luc [Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec G1K 7P4 (Canada) and Departement de Radio-Oncologie, Hotel-Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec G1R 2J6 (Canada); Departement de Radio-Oncologie, Hotel-Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec G1R 2J6 (Canada); Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec G1K 7P4 (Canada) and Departement de Radio-Oncologie, Hotel-Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec G1R 2J6 (Canada); Department of Radiation Physics, Unit 94, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States); Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec G1K 7P4 (Canada) and Departement de Radio-Oncologie, Hotel-Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec G1R 2J6 (Canada)

    2012-01-15

    Purpose: To compare the performance of plastic scintillation detectors (PSD) for quality assurance (QA) in stereotactic radiosurgery conditions to a microion-chamber (IC), Gafchromic EBT2 films, 60 008 shielded photon diode (SD) and unshielded diodes (UD), and assess a new 2D crosshair array prototype adapted to small field dosimetry. Methods: The PSD consists of a 1 mm diameter by 1 mm long scintillating fiber (BCF-60, Saint-Gobain, Inc.) coupled to a polymethyl-methacrylate optical fiber (Eska premier, Mitsubishi Rayon Co., Ltd., Tokyo, Japan). Output factors (S{sub c,p}) for apertures used in radiosurgery ranging from 4 to 40 mm in diameter have been measured. The PSD crosshair array (PSDCA) is a water equivalent device made up of 49 PSDs contained in a 1.63 cm radius area. Dose profiles measurements were taken for radiosurgery fields using the PSDCA and were compared to other dosimeters. Moreover, a typical stereotactic radiosurgery treatment using four noncoplanar arcs was delivered on a spherical phantom in which UD, IC, or PSD was placed. Using the Xknife planning system (Integra Radionics Burlington, MA), 15 Gy was prescribed at the isocenter, where each detector was positioned. Results: Output Factors measured by the PSD have a mean difference of 1.3% with Gafchromic EBT2 when normalized to a 10 x 10 cm{sup 2} field, and 1.0% when compared with UD measurements normalized to the 35 mm diameter cone. Dose profiles taken with the PSD crosshair array agreed with other single detectors dose profiles in spite of the presence of the 49 PSDs. Gamma values comparing 1D dose profiles obtained with PSD crosshair array with Gafchromic EBT2 and UD measured profiles shows 98.3% and 100.0%, respectively, of detector passing the gamma acceptance criteria of 0.3 mm and 2%. The dose measured by the PSD for a complete stereotactic radiosurgery treatment is comparable to the planned dose corrected for its SD-based S{sub c,p} within 1.4% and 0.7% for 5 and 35 mm diameter cone, respectively. Furthermore, volume averaging of the IC can be observed for the 5 mm aperture where it differs by as much as 9.1% compared to the PSD measurement. The angular dependency of the UD is also observed, unveiled by an under-response around 2.5% of both 5 and 35 mm apertures. Conclusions: Output Factors and dose profiles measurements performed, respectively, with the PSD and the PSDCA were in agreement with those obtained with the UD and EBT2 films. For stereotactic radiosurgery treatment verification, the PSD gives accurate results compared to the planning system and the IC once the latter is corrected to compensate for the averaging effect of the IC. The PSD provides precise results when used as a single detector or in a dense array, resulting in a great potential for stereotactic radiosurgery QA measurements.

  19. Qualitative and quantitative analysis of cinobufacini injection using rapid separation liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry and HPLC-photodiode array detection, a feasible strategy for the quality control of Chinese medicine injections.

    PubMed

    Zhao, Haiyu; Wu, Xu; Wang, Hongjie; Gao, Bo; Yang, Jian; Si, Nan; Bian, Baolin

    2013-02-01

    Cinobufacini injection, prepared from the skin of Bufo bufo gargarizans Cantor, has presented its significant effects on the treatment of hepatitis and various cancers in the clinic. However, as an unclear complex chemical system, the optimization of its quality control markers has been a long-term challenge. In present study, a feasible strategy integrated markers screening, determination, and statistical analysis was efficiently proposed, especially for the undefined Chinese medicine injections. First, rapid separation LC-quadrupole-TOF-MS method was applied in the identification of 19 major compounds in the cinobufacini injection for the first time. Further, nine high-level contents active compounds were selected as quality control markers for the quantification analysis. An acceptable and validated determination method was established in 17 batches of cinobufacini injection by HPLC-photodiode array detection method, including linear regression relationship (r(2), 0.9996-1), precisions (RSD, 0.02-1.35%), repeatability (RSD, 0.05-1.97%), stability (RSD, 0.1-3.85%), and recovery (95.88-104.89%). Each analyte was detected at its maximum ultraviolet spectra wavelength. Finally, based on the quantification results, principal component analysis was performed on the quality assessment of cinobufacini injections. This three-step strategy provides a newly feasible solution for the quality control of Chinese medicine injections. PMID:23292876

  20. Ultrasound-assisted matrix solid phase dispersive extraction for the simultaneous analysis of ?-lactams (four penicillins and eight cephalosporins) in milk by high performance liquid chromatography with photodiode array detection.

    PubMed

    Karageorgou, Eftichia G; Samanidou, Victoria F; Papadoyannis, Ioannis N

    2012-10-01

    The application of ultrasound-assisted matrix solid phase dispersive extraction for the confirmatory analysis of 12 ?-lactam antibiotics in milk by high performance liquid chromatography with photodiode array detection has been proposed herein. Four penicillins (cloxacillin, dicloxacillin, oxacillin, and amoxicillin) and eight cephalosporins (cefaclor, cefadroxil, ceftiofur, cefuroxime, cefoperazone, cefazolin, cephalexin, and cefotaxime) are effectively extracted using a mixed sorbent of Quick Easy Cheap Effective Rugged Safe technique and OASIS HLB providing a matrix free from any endogenous interference. Examined analytes were well resolved on an Inertsil ODS-3 analytical column with a mobile phase of CH(3)COONH(4) (0.05 M) and acetonitrile delivered under a gradient program. 1,7-Dimethyl-xanthine was used as internal standard. The method was validated meeting the European Legislation determining linearity, selectivity, stability, decision limit, detection capability, accuracy, precision, and ruggedness according to the Youden approach. Recoveries of all antibiotics rated from 85.0 to 115.7%, while RSD values were <12.7%. Finally, the method was successfully applied to milk samples purchased from local market. PMID:22941669

  1. Robust method for investigating nitrogen metabolism of 15N labeled amino acids using AccQ昑ag ultra performance liquid chromatography-photodiode array-electrospray ionization-mass spectrometry: application to a parasitic plant-plant interaction.

    PubMed

    Gaudin, Zachary; Cerveau, Delphine; Marnet, Nathalie; Bouchereau, Alain; Delavault, Philippe; Simier, Philippe; Pouvreau, Jean-Bernard

    2014-01-21

    An AccQ昑ag ultra performance liquid chromatography-photodiode array-electrospray ionization-mass spectrometry (AccQ昑ag-UPLC-PDA-ESI-MS) method is presented here for the fast, robust, and sensitive quantification of (15)N isotopologue enrichment of amino acids in biological samples, as for example in the special biotic interaction between the cultivated specie Brassica napus (rapeseed) and the parasitic weed Phelipanche ramosa (broomrape). This method was developed and validated using amino acid standard solutions containing (15)N amino acid isotopologues and/or biological unlabeled extracts. Apparatus optimization, limits of detection and quantification, quantification reproducibility, and calculation method of (15)N isotopologue enrichment are presented. Using this method, we could demonstrate that young parasite tubercles assimilate inorganic nitrogen as (15)N-ammonium when supplied directly through batch incubation but not when supplied by translocation from host root phloem, contrary to (15)N2-glutamine. (15)N2-glutamine mobility from host roots to parasite tubercles followed by its low metabolism in tubercles suggests that the host-derived glutamine acts as an important nitrogen containing storage compound in the young tubercle of Phelipanche ramosa. PMID:24359440

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

    E-print Network

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

    2007-10-11

    A large BaF2 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 gamma rays (E>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 cm X 3.5 cm X 35.0 cm). 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.

  3. LAMBDA: Large Area Modular BaF2 Detector Array for the measurement of high energy ? 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 ? 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 3.53.5 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.

  4. Non-local means-based nonuniformity correction for infrared focal-plane array detectors

    NASA Astrophysics Data System (ADS)

    Yu, Hui; Zhang, Zhi-jie; Chen, Fu-sheng; Wang, Chen-sheng

    2014-11-01

    The infrared imaging systems are normally based on the infrared focal-plane array (IRFPA) which can be considered as an array of independent detectors aligned at the focal plane of the imaging system. Unfortunately, every detector on the IRFPA may have a different response to the same input infrared signal which is known as the nonuniformity problem. Then we can observe the fixed pattern noise (FPN) from the resulting images. Standard nonuniformity correction (NUC) methods need to be recalibrated after a short period of time due the temporal drift of the FPN. Scene-based nonuniformity correction (NUC) techniques eliminate the need for calibration by correction coefficients based on the scene being viewed. However, in the scene-based NUC method the problem of ghosting artifacts widely seriously decreases the image quality, which can degrade the performance of many applications such as target detection and track. This paper proposed an improved scene-based method based on the retina-like neural network approach. The method incorporates the use of non-local means (NLM) method into the estimation of the gain and the offset of each detector. This method can not only estimates the accurate correction coefficient but also restrict the ghosting artifacts efficiently. The proposed method relies on the use of NLM method which is a very successful image denoising method. And then the NLM used here can preserve the image edges efficiently and obtain a reliable spatial estimation. We tested the proposed NUC method by applying it to an IR sequence of frames. The performance of the proposed method was compared the other well-established adaptive NUC techniques.

  5. Intensity information extraction in Geiger mode detector array based three-dimensional imaging applications

    NASA Astrophysics Data System (ADS)

    Wang, Fei

    2013-09-01

    Geiger-mode detectors have single photon sensitivity and picoseconds timing resolution, which make it a good candidate for low light level ranging applications, especially in the case of flash three dimensional imaging applications where the received laser power is extremely limited. Another advantage of Geiger-mode APD is their capability of large output current which can drive CMOS timing circuit directly, which means that larger format focal plane arrays can be easily fabricated using the mature CMOS technology. However Geiger-mode detector based FPAs can only measure the range information of a scene but not the reflectivity. Reflectivity is a major characteristic which can help target classification and identification. According to Poisson statistic nature, detection probability is tightly connected to the incident number of photon. Employing this relation, a signal intensity estimation method based on probability inversion is proposed. Instead of measuring intensity directly, several detections are conducted, then the detection probability is obtained and the intensity is estimated using this method. The relation between the estimator's accuracy, measuring range and number of detections are discussed based on statistical theory. Finally Monte-Carlo simulation is conducted to verify the correctness of this theory. Using 100 times of detection, signal intensity equal to 4.6 photons per detection can be measured using this method. With slight modification of measuring strategy, intensity information can be obtained using current Geiger-mode detector based FPAs, which can enrich the information acquired and broaden the application field of current technology.

  6. Development of a unit cell for a Ge:Ga detector array

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Two modules of gallium-doped germanium (Ge:Ga) infrared detectors with integrated multiplexing readouts and supporting drive electronics were designed and tested. This development investigated the feasibility of producing two-dimensional Ge:Ga arrays by stacking linear modules in a housing capable of providing uniaxial stress for enhanced long-wavelength response. Each module includes 8 detectors (1x1x2 mm) mounted to a sapphire board. The element spacing is 12 microns. The back faces of the detector elements are beveled with an 18 deg angle, which was proved to significantly enhance optical absorption. Each module includes a different silicon metal-oxide semiconductor field effect transistor (MOSFET) readout. The first circuit was built from discrete MOSFET components; the second incorporated devices taken from low-temperature integrated circuit multiplexers. The latter circuit exhibited much lower stray capacitance and improved stability. Using these switched-FET circuits, it was demonstrated that burst readout, with multiplexer active only during the readout period, could successfully be implemented at approximately 3.5 K.

  7. [Research on the neas infrared focal plane array detector imaging technology used in the laser warning].

    PubMed

    Wang, Zhi-Bin; Huang, Yan-Fei; Wang, Yao-Li; Zhang, Rui; Wang, Yan-Chao

    2014-04-01

    In order to achieve the incoming laser's accurate position, it is necessary to improve the detected laser's direction resolution. The InGaAs focal plane array detector with the type of FPA-320 x 256-C was selected as the core component of the diffraction grating laser warning device. The detection theory of laser wavelength and direction based on diffraction grating was introduced. The drive circuit was designed through the analysis of the detector's performance and parameters. Under the FPGA' s timing control, the detector's analog output was sampled by the high-speed AD. The data was cached to FPGA's extended SRAM, and then transferred to a PC through USB. Labview on a PC collects the raw data for processing and displaying. The imaging experiments were completed with the above method. With the wavelength of 1550 nm and 980 nm laser from different directions the diffraction images were detected. Through analysis the location of the zero order and one order can be determined. According to the grating diffraction theory, the wavelength and the direction of the two-dimensional angle can be calculated. It indicates that the wavelength error is less than 10 nm, and the angle error is less than 1 degrees. PMID:25007645

  8. Evaluation of linear array MOSFET detectors for in vivo dosimetry to measure rectal dose in HDR brachytherapy

    Microsoft Academic Search

    Aisling Haughey; George Coalter; Koki Mugabe

    The study aimed to assess the suitability of linear array metal oxide semiconductor field effect transistor detectors (MOSFETs)\\u000a as in vivo dosimeters to measure rectal dose in high dose rate brachytherapy treatments. The MOSFET arrays were calibrated\\u000a with an Ir192 source and phantom measurements were performed to check agreement with the treatment planning system. The angular\\u000a dependence, linearity and constancy

  9. Physics-based simulation of the modulation transfer function in HgCdTe infrared detector arrays.

    PubMed

    Pinkie, Benjamin; Schuster, Jonathan; Bellotti, Enrico

    2013-07-15

    We have developed a numerical technique for performing physics-based simulations of the modulation transfer function (MTF) of infrared detector focal plane arrays. The finite-difference time-domain and finite element methods are employed to determine the electromagnetic and electrical response, respectively. We show how the total MTF can be decomposed to analyze the effect of lateral diffusion of charge carriers and present several methods for mitigation of such effects. We employ our numerical technique to analyze the MTF of a HgCdTe two-color bias-selectable infrared detector array. PMID:23939107

  10. Coherent summation of spatially distorted laser Doppler signals by using a two-dimensional heterodyne detector array

    NASA Technical Reports Server (NTRS)

    Chan, Kin P.; Killinger, Dennis K.

    1992-01-01

    Phase-sensitive coherent summation of individual heterodyne detector array signals was demonstrated for the enhanced detection of spatially distorted laser Doppler returns. With the use of a 2 x 2 heterodyne detector array, the phase and amplitude of a time-varying speckle pattern was detected, and the signal-to-noise ratio of the Doppler shift estimate was shown to be improved by a factor of 2, depending on the extent of spatial coherence loss. These results are shown to agree with a first-order analysis and indicate the advantage of coherent summation for both short-range laser Doppler velocimetry and long-range atmospheric coherent lidar.

  11. Optical fiber readout of scintillator arrays using a multi-channel PMT: a high resolution PET detector for animal imaging

    Microsoft Academic Search

    Simon R. Cherry; Yiping Shao; Stefan Siegel; Robert W. Silverman; Erkan Mumcuoglu; Ken Meadors; Michael E. Phelps

    1996-01-01

    The authors report the results from a new high resolution gamma ray imaging detector designed for use in a positron emission tomography (PET) system dedicated to small animal imaging. The detectors consist of an 88 array of 2󫎽0 mm bismuth germanate (BGO) crystals coupled by 2 mm diameter double clad optical fibers to a 64 pixel multi-channel photomultiplier tube (MC-PMT).

  12. Third-generation infrared photodetector arrays

    NASA Astrophysics Data System (ADS)

    Rogalski, A.; Antoszewski, J.; Faraone, L.

    2009-05-01

    Hitherto, two distinct families of multielement detector arrays have been used for infrared (IR) imaging system applications: linear arrays for scanning systems (first generation) and two-dimensional arrays for staring systems (second generation). Nowadays, third-generation IR systems are being developed which, in the common understanding, provide enhanced capabilities such as larger numbers of pixels, higher frame rates, better thermal resolution, multicolor functionality, and/or other on-chip signal-processing functions. In this paper, fundamental and technological issues associated with the development and exploitation of third-generation IR photon detectors are discussed. In this class of detectors the two main competitors, HgCdTe photodiodes and quantum-well photoconductors, are considered. This is followed by discussions focused on the most recently developed focal plane arrays based on type-II strained-layer superlattices and quantum dot IR photodetectors. The main challenges facing multicolor devices are concerned with complicated device structures, thicker and multilayer material growth, and more difficult device fabrication, especially for large array sizes and/or small pixel dimensions. This paper also presents and discusses the ongoing detector technology challenges that are being addressed in order to develop third-generation infrared photodetector arrays.

  13. Irradiation stability of silicon photodiodes for extreme-ultraviolet radiation

    NASA Astrophysics Data System (ADS)

    Scholze, Frank; Klein, Roman; Bock, Thomas

    2003-10-01

    Photodiodes are used as easy-to-operate detectors in the extreme-ultraviolet spectral range. At the Physikalisch-Technische Bundesanstalt photodiodes are calibrated with an uncertainty of spectral responsivity of 0.3% or less. Stable photodiodes are a prerequisite for the dissemination of these high-accuracy calibrations to customers. Silicon photodiodes with different top layers were exposed to intense extreme-ultraviolet irradiation. Diodes coated with diamondlike carbon or TiSiN proved to be stable within a few percent up to a radiant exposure of 100 kJ/cm2. The changes in responsivity could be explained as being due to carbon contamination and to changes in the internal charge collection efficiency. In ultrahigh vacuum, no indication of oxidation was found.

  14. Three-dimensional numerical simulation of planar P+n heterojunction In0.53Ga0.47As photodiodes in dense arrays part II: modulation transfer function modeling

    NASA Astrophysics Data System (ADS)

    Wichman, Adam R.; DeWames, Roger E.; Bellotti, Enrico

    2014-06-01

    Processing improvements have facilitated manufacturing reduced pixel dimensions for lattice-matched InGaAs on InP short-wave infrared detectors. Due to its technological maturity, this material system continues to garner attention for low-light level imaging applications. With pixel dimensions smaller than minority carrier diffusion lengths, optimizing array performance by reducing crosstalk from lateral carrier diffusion remains an important design issue. Analytical models, however, have provided limited insight on underlying mechanisms limiting device performance in the conventional planar double heterointerface device. Quantitative modeling provides tools to investigate performance sensitivities and their underlying mechanisms. In this work we develop a three-dimensional numerical simulation for dense P+n In0.53Ga0.47As on InP photo detector focal plane arrays using a conventional planar, back-illuminated structure. We evaluate optical generation with finite-difference time-domain analysis, and model carrier transport in a drift diffusion analysis simultaneously solving the carrier continuity and Poisson equations. Using this model we investigate modulation transfer function variations with pixel pitch and diffused junction geometries for small dimension arrays. By accounting for carrier diffusion effects, these results should provide a benchmark against which to evaluate modulation transfer function contributions from other effects, such as crosstalk attributable to photon recycling.

  15. Effect of atmospheric turbulence on the bit error probability of a space to ground near infrared laser communications link using binary pulse position modulation and an avalanche photodiode detector

    NASA Technical Reports Server (NTRS)

    Safren, H. G.

    1987-01-01

    The effect of atmospheric turbulence on the bit error rate of a space-to-ground near infrared laser communications link is investigated, for a link using binary pulse position modulation and an avalanche photodiode detector. Formulas are presented for the mean and variance of the bit error rate as a function of signal strength. Because these formulas require numerical integration, they are of limited practical use. Approximate formulas are derived which are easy to compute and sufficiently accurate for system feasibility studies, as shown by numerical comparison with the exact formulas. A very simple formula is derived for the bit error rate as a function of signal strength, which requires only the evaluation of an error function. It is shown by numerical calculations that, for realistic values of the system parameters, the increase in the bit error rate due to turbulence does not exceed about thirty percent for signal strengths of four hundred photons per bit or less. The increase in signal strength required to maintain an error rate of one in 10 million is about one or two tenths of a db.

  16. A 48 APD array, consisting of two monolithic silicon wafers, coupled to a 32-channel LSO matrix for high-resolution PET

    Microsoft Academic Search

    Bernd J. Pichler; Florian Bernecker; Guido B鰊ing; Magdalena Rafecas; Wendelin Pimpl; Markus Schwaiger; Eckart Lorenz; Sibylle I. Ziegler

    2001-01-01

    Avalanche photodiodes (APDs) offer new design options for high-resolution positron emission tomography (PET) detectors. The goal of this study was the design of a very compact PET detector module with two layers. For this purpose, new monolithic arrays of 48 densely packed APDs (each with a 1.61.6 mm2 sensitive area) were developed and evaluated for their suitability to read out

  17. High-speed visible-blind GaN-based indiumtinoxide Schottky photodiodes

    E-print Network

    Aytur, Orhan

    layers, AlxGa1 xN/GaN-based visible/solar-blind photodiodes PDs with excellent detector performances haveHigh-speed visible-blind GaN-based indium璽in璷xide Schottky photodiodes Necmi Biyikli,a) Tolga Ankara 06533, Turkey Received 5 July 2001; accepted for publication 13 August 2001 We have fabricated GaN

  18. Device localization and dynamic scan plane selection using a wireless MRI detector array

    PubMed Central

    Riffe, Matthew J.; Yutzy, Stephen R.; Jiang, Yun; Twieg, Michael D.; Blumenthal, Colin J.; Hsu, Daniel P.; Pan, Li; Gilson, Wesley D.; Sunshine, Jeffrey L.; Flask, Christopher A.; Duerk, Jeffrey L.; Nakamoto, Dean; Gulani, Vikas; Griswold, Mark A.

    2013-01-01

    Purpose A prototype wireless guidance device using single sideband amplitude modulation (SSB) is presented for a 1.5T MRI system. Methods The device contained three fiducial markers each mounted to an independent receiver coil equipped with wireless SSB technology. Acquiring orthogonal projections of these markers determined the position and orientation of the device, which was used to define the scan plane for a subsequent image acquisition. Device localization and scan plane update required approximately 30 ms, so it could be interleaved with high temporal resolution imaging. Since the wireless device is used for localization and doesn抰 require full imaging capability, the design of the SSB wireless system was simplified by allowing an asynchronous clock between the transmitter and receiver. Results When coupled to a high readout bandwidth, the error caused by the lack of a shared frequency reference was quantified to be less than one pixel (0.78 mm) in the projection acquisitions. Image-guidance with the prototype was demonstrated with a phantom where a needle was successfully guided to a target and contrast was delivered. Conclusion The feasibility of active tracking with a wireless detector array is demonstrated. Wireless arrays could be incorporated into devices to assist in image-guided procedures. PMID:23900921

  19. Design of a smart pixel multispectral imaging array using 3D stacked thin film detectors on Si CMOS circuits

    Microsoft Academic Search

    K. Lee; S. Seo; S. Huang; Y. Joo; W. A. Doolittle; S. Fike; N. Jokerst; M. Brooke; A. Brown

    2000-01-01

    We discuss the design of a smart multispectral imaging system which can be fabricated with independently optimized detector arrays and Si CMOS circuits, which are stacked in three dimensions on top of one another for complete physical registration of the multispectral image. This smart multispectral imager utilizes the heterogeneous integration of thin film GaN (UV), MCT (MWIR), and Si CMOS

  20. Extraction of real-space correlation function of a rough surface by light scattering using diode array detectors

    E-print Network

    Wang, Gwo-Ching

    Extraction of real-space correlation function of a rough surface by light scattering using diode distribution profile of light scattering. A novel diode array detectors arrangement was used to obtain-ray dif- fraction, atom diffraction, and light scattering, are also useful in the quantitative study

  1. Detection of ultra-high energy neutrino interactions in ice: comparing radio detector array designs

    NASA Astrophysics Data System (ADS)

    Bechtol, Keith; Vieregg, Abigail

    2014-08-01

    Ultra-high energy (UHE, >10^18 eV) cosmic neutrinos are anticipated to reveal the most distant, most obscured, and highest energy particle accelerators in the Universe. An almost guaranteed flux of UHE neutrinos is predicted from the interactions of UHE cosmic rays with the cosmic microwave background, and additional contributions may arise from prompt emission at individual sources. The spectrum of UHE neutrinos is a sensitive discriminator of the cosmological evolution of UHE sources, as well as the composition of UHE cosmic rays. At the same time, UHE neutrinos will enable several tests of fundamental physics, including constraints on the neutrino-nucleon interaction cross section at center-of-momentum energies ~100 TeV, and searches for Lorentz invariance violation.Theoretical predictions and subsequent laboratory measurements of coherent radio emission from showers initiated by neutrino interactions in dielectric media (e.g., ice, sand, salt, lunar regolith) have motivated diverse experimental approaches involving "detectors" comprised of up to millions of cubic kilometers of natural materials. I will discuss simulation results comparing the expected performance of several proposed radio detector array designs with subterranean, ice shelf, and above ice configurations.

  2. Developments in HgCdTe avalanche photodiode technology and applications

    NASA Astrophysics Data System (ADS)

    Ashcroft, Andrew; Baker, Ian

    2010-04-01

    SELEX Galileo has developed avalanche photodiode technology in HgCdTe to serve a whole range of applications in defence, security, commercial and space research. Burst-illumination LIDAR (BIL), using a near-infrared pulse laser and a fast, gated detector, is now adopted for most long range imaging applications. New results from range trials using prototype systems based on multifunctional and 3D detectors are reported. In the astronomy field, APD arrays at 2.5 ?m cutoff can provide near-single photon sensitivity for future wavefront sensors and interferometric applications. Under a contract from European Southern Observatories arrays have been successfully demonstrated with gains up to 20 and negligible dark current at 77K. Under a European Space Agency contract, a large area, single element detector has been designed for the 2.015?m CO2 absorption line. The sensor is specifically designed to be operated at 200K so that thermoelectric cooling is viable. The element is made up of many sub-pixel diodes each deselectable to ensure high breakdown in the macro-pixel. The latest results of the detector and its associated transimpedance amplifier (TIA) are presented.

  3. Progress in the use of avalanche photodiodes for readout for calorimeters

    SciTech Connect

    Fenker, H.; Morgan, K.; Regan, T.

    1991-09-01

    During the past year the Superconducting Super Collider Tracking Group has progressed from acquisition of its first avalanche photodiode (APD) to installation of a 96-channel array of the devices. The work was motivated by the desire to learn how to use APDs as the sensitive elements in a fiber tracking detector, moderated by the presence of limited resources and the absence of activity within groups outside the SSC Laboratory on such a project. We chose, therefore, to team up with an ongoing research effort which intended to evaluate both pre-shower and shower-maximum detectors and various means of sensing the light produced. The pre-shower detector is made of layers of scintillating fibers similar to a fiber tracker. The shower-maximum detector uses optical fibers to transmit the light from scintillating plates to the readout devices. Our contribution has been to develop the APD array for use in this test from concept to operation. Currently, the equipment is installed in Fermilab's MP beamline awaiting delivery to the final 36 APDs and exposure to the beam. 9 refs., 18 figs.

  4. Cuban and Brazilian red propolis: botanical origin and comparative analysis by high-performance liquid chromatography-photodiode array detection/electrospray ionization tandem mass spectrometry.

    PubMed

    Piccinelli, Anna Lisa; Lotti, Cinzia; Campone, Luca; Cuesta-Rubio, Osmany; Campo Fernandez, Mercedes; Rastrelli, Luca

    2011-06-22

    Chemical composition of propolis depends on the specificity of the local flora at the site of collection and thus on the geographic and climatic characteristics of this place. This paper describes a comparative analysis of Cuban red propolis (CRP), Brazilian red propolis (BRP), and Dalbergia ecastophyllum exudates (DEE) by high-performance liquid chromatography with diode-array detection and tandem mass spectrometry. The aim of this study was to investigate the overall chemical profile and the botanical origin of red propolis and to suggest similarities and differences between samples collected in different tropical regions. Isoliquiritigenin (1), liquiritigenin and naringenin (2 and 17), isoflavones (3-4 and 16), isoflavans (5-7 and 18), and pterocarpans (8-13) were detected in CRP, BRP, and DEE, whereas polyisoprenylated benzophenones (PPBs) guttiferone E/xanthochymol (14a,b) and oblongifolin A (15) were detected only in BRP. Pigments responsible for the red color of DEE and red propolis were also identified as two C30 isoflavans, the new retusapurpurin B (19) and retusapurpurin A (20). PPBs and pigments were isolated and unambiguously characterized by 1D and 2D NMR analysis. These results show that red propolis samples from different tropical zones have a similar chemical composition. DEE is the main red propolis source, but the presence of PPBs in BRP suggests the contribution of different botanical sources for Brazilian samples. This chemical information is important for quality control of red propolis and its commercial products and for biological study. PMID:21598949

  5. Ultraviolet photodetectors and imaging arrays based on III-V nitride heterostructures

    NASA Astrophysics Data System (ADS)

    Brown, Jeffrey David

    2000-10-01

    The III-V nitride class of compound semiconductors has received much attention in the last decade. These materials have a wide, direct bandgap, making them a prime candidate for optoelectronic devices in the blue, green, and ultraviolet spectral regions. These materials exhibit impressive optical, electrical, and thermal properties, even though there are fundamental materials issues that are thus far unresolved. This work explores the application of III-V nitride semiconductors to optical detectors in the ultraviolet region of the electromagnetic spectrum. Metalorganic vapor phase epitaxy was used to synthesize thin film p-i-n photodiode structures on double side polished sapphire substrates; these films were characterized for optical, electrical and structural properties. The grown structures were designed to respond to a predetermined region of the UV spectrum when illuminated from the substrate side. These structures were fabricated into devices using generally accepted techniques for dry etching and p and n-contact metallizations. Test devices were characterized using tools developed by the author. These devices demonstrated as high as 80% quantum efficiency and extremely low dark currents; resulting in spectral detectivities as large as 6 * 1013 cmHz1/2W-1. Devices were designed and demonstrated for a series of detection regions ranging from 365 nm to 250 nm. Photolithography masks were designed to allow the fabrication of photodiode arrays that would hybridize to commercially available CMOS based readout integrated circuits (ROICs), used routinely for infrared photodiode imaging. Photodiode arrays were fabricated and indium bumps were deposited onto the diode contacts and the ROICs to provide electrical connection. The hybrid detector arrays were placed in leadless chip carriers, wirebonded, and connected to commercially available drive and readout circuitry. Images of UV scenes were focused onto the arrays using fused quartz lenses. These images and movies were successfully collected at frame rates up to 240 Hz using both 32 x 32 and 128 x 128 III-V nitride based UV photodiode imagers.

  6. Retrieval of ultraviolet spectral irradiance from filtered photodiode measurements

    NASA Astrophysics Data System (ADS)

    Zorzano, Mar韆-Paz; V醶quez, Luis; Jimenez, Salvador

    2009-11-01

    We derived a general purpose method to retrieve the ultraviolet (UV) spectral irradiance using filtered photodiodes. The algorithm retrieves through an iterative process, which is based on the application of the mean value theorem, the six unknown coefficients of an interpolating polynomial function of order 5. For illustration we retrieve the incident spectral irradiance of three representative study cases. We consider the output currents induced on six SiC filtered photodiodes by a D2 lamp in vacuum, by the same lamp with ozone absorption and by a Martian-like solar spectrum. The algorithm converges to an interpolating function that reproduces the spectrum within the range of response of the photodiodes and with an integral error <0.6% for each channel for the vacuum D2 spectrum. Since two photodiodes are centered on the ozone absorption band, this method successfully detects ozone absorption and estimates its ambient terrestrial concentration with <4% error. This algorithm will be used to retrieve the Martian surface incident spectrum with REMS UV photodiodes on board the MSL Rover mission (NASA). This method can be equivalently used with commercial photodiodes for other applications where an inexpensive, small and light detector is preferred to conventional spectroradiometers.

  7. Determination of selected water-soluble vitamins using hydrophilic chromatography: a comparison of photodiode array, fluorescence, and coulometric detection, and validation in a breakfast cereal matrix.

    PubMed

    Langer, Swen; Lodge, John K

    2014-06-01

    Water-soluble vitamins are an important class of compounds that require quantification from food sources to monitor nutritional value. In this study we have analysed six water-soluble B vitamins ([thiamine (B1), riboflavin (B2), nicotinic acid (B3, NAc), nicotinamide (B3, NAm), pyridoxal (B6), folic acid (B9)], and ascorbic acid (vit C) with hydrophilic interaction liquid chromatography (HILIC), and compared UV, fluorescent (FLD) and coulometric detection to optimise a method to quantitate the vitamins from food sources. Employing UV/diode array (DAD) and fluorimetric detection, six B vitamins were detected in a single run using gradient elution from 100% to 60% solvent B [10mM ammonium acetate, pH 5.0, in acetonitrile and water 95:5 (v:v)] over 18 min. UV detection was performed at 268 nm for B1, 260 nm for both B3 species and 284 nm for B9. FLD was employed for B2 at excitation wavelength of 268 nm, emission of 513 nm, and 284 nm/317 nm for B6. Coulometric detection can be used to detect B6 and B9, and vit C, and was performed isocratically at 75% and 85% of solvent B, respectively. B6 was analysed at a potential of 720 mV, while B9 was analysed at 600 mV, and vit C at 30 mV. Retention times (0.96 to 11.81 min), intra-day repeatability (CV 1.6 to 3.6), inter-day variability (CV 1.8 to 11.1), and linearity (R 0.9877 to 0.9995) remained good under these conditions with limits of detection varying from 6.6 to 164.6 ng mL(-1), limits of quantification between 16.8 and 548.7 ng mL(-1). The method was successfully applied for quantification of six B vitamins from a fortified food product and is, to our knowledge, the first to simultaneously determine multiple water-soluble vitamins extracted from a food matrix using HILIC. PMID:24792530

  8. Uncooled infrared detector with 12?m pixel pitch video graphics array

    NASA Astrophysics Data System (ADS)

    Endoh, Tsutomu; Tohyama, Shigeru; Yamazaki, Takao; Tanaka, Yutaka; Okuyama, Kuniyuki; Kurashina, Seiji; Miyoshi, Masaru; Katoh, Kouji; Yamamoto, Takashi; Okuda, Yuuhi; Sasaki, Tokuhito; Ishizaki, Haruo; Nakajima, Tomohiko; Shinoda, Kentaro; Tsuchiya, Tetsuo

    2013-06-01

    Uncooled infrared detectors with 12?m pixel pitch video graphics array (VGA) have been developed. To improve the signal to noise ratio (SNR) for 12?m pixel pitch, a highly sensitive bolometer material, an advanced pixel structure for thermal isolation and a newly designed read-out IC (ROIC) have been also developed. The bolometer material has been improved by using vanadium niobate. Over a wide range of temperature, temperature coefficient of resistance (TCR) is achieved higher level than -3.6%/K, which is 2 times higher than that for the conventional bolometer material. For thermal isolation, thermal conductance (Gth) value for the new pixel structure, fabricated by using triple level sacrificial layer process, is estimated to be 5nW/K, which is 1/5 times lower than that for the conventional pixel structure. On the other hand, since the imaging area is reduced by the pixel pitch, the uniformity of pixel can be improved. This enables to remove the non-uniformity correction (NUC) circuit in the ROIC. Removal of this circuit is effective for low power and low noise. This 12?m pixel pitch VGA detector is packaged in a compact (24 24 6.5 mm) and lightweight (11g) ceramic package. In addition, it has been incorporated in a newly developed prototype miniature imager. The miniature imager has dimension of 25(H) 25(W) 28(L) mm and weight of 30g. This imager is compact and small enough to fit in your hand. Hereafter, this imager is greatly expected to be applied to mobile systems.

  9. Microwave Nonlinearities in Photodiodes

    Microsoft Academic Search

    Keith Jake Williams

    1994-01-01

    The nonlinearities in p-i-n photodiodes have been measured and numerically modeled. Harmonic distortion, response reduction, and sinusoidal output distortion measurements were made with two single-frequency offset-phased-locked Nd:YAG lasers, which provided a source dynamic range greater than 130 dB, a 1 MHz to 50 GHz frequency range, and optical powers up to 10 mW. A semi-classical approach was used to solve

  10. Update on the Fabrication and Performance of 2-D Arrays of Superconducting Magnesium Diboride (MgB2) Thermal Detectors for Outer-Planets Exploration

    NASA Technical Reports Server (NTRS)

    Lakew, Brook; Aslam, S.

    2011-01-01

    Detectors with better performance than the current thermopile detectors that operate at room temperature will be needed at the focal plane of far-infrared instruments on future planetary exploration missions. We will present an update on recent results from the 2-D array of MgB2 thermal detectors being currently developed at NASA Goddard. Noise and sensitivity results will be presented and compared to thermal detectors currently in use on planetary missions.

  11. Hybrid AlGaN-SiC Avalanche Photodiode for Deep-UV Photon Detection

    NASA Technical Reports Server (NTRS)

    Aslam, Shahid; Herrero, Federico A.; Sigwarth, John; Goldsman, Neil; Akturk, Akin

    2010-01-01

    The proposed device is capable of counting ultraviolet (UV) photons, is compatible for inclusion into space instruments, and has applications as deep- UV detectors for calibration systems, curing systems, and crack detection. The device is based on a Separate Absorption and Charge Multiplication (SACM) structure. It is based on aluminum gallium nitride (AlGaN) absorber on a silicon carbide APD (avalanche photodiode). The AlGaN layer absorbs incident UV photons and injects photogenerated carriers into an underlying SiC APD that is operated in Geiger mode and provides current multiplication via avalanche breakdown. The solid-state detector is capable of sensing 100-to-365-nanometer wavelength radiation at a flux level as low as 6 photons/pixel/s. Advantages include, visible-light blindness, operation in harsh environments (e.g., high temperatures), deep-UV detection response, high gain, and Geiger mode operation at low voltage. Furthermore, the device can also be designed in array formats, e.g., linear arrays or 2D arrays (micropixels inside a superpixel).

  12. Initial results from the Sherbrooke avalanche photodiode positron tomograph

    Microsoft Academic Search

    R. Lecomte; J. Cadorette; S. Rodrigue; D. Lapointe; D. Rouleau; M. Bentourkia; R. Yao; P. Msaki

    1996-01-01

    The design features and engineering constraints of a PET system based on avalanche photodiode (APD) detectors have been described in a previous report. Here, the authors present the initial results obtained with the Sherbrooke APD-PET scanner, a very high spatial resolution device designed for dynamic imaging of small and medium-sized laboratory animals such as rats, cats, rabbits and small monkeys.

  13. Effect of detector nonlinearity and image persistence on CARS derived temperatures

    Microsoft Academic Search

    D. R. Snelling; G. J. Smallwood; T. Parameswaran

    1989-01-01

    The image persistence of self-scanning photodiode arrays (IPDA) incorporating P-20 phosphor-based intensifiers is shown to make them unsuitable for single-pulse CARS temperature measurements in turbulent combustion. Correcting CARS flame spectra for the nonlinear response of the IPDA detectors increases CARS-derived temperatures by about 3-6 percent. This error is partially offset by correcting for the perturbations in the N2 vibrational population

  14. Effect of detector nonlinearity and image persistence on CARS derived temperatures

    Microsoft Academic Search

    D. R. Snelling; G. J. Smallwood; T. Parameswaran

    1989-01-01

    The image persistence of self-scanning photodiode arrays (IPDA) incorporating P-20 phosphor-based intensifiers is shown to make them unsuitable for single-plus CARS temperature measurements in turbulent combustion. Correcting CARS flame spectra for the nonlinear response of the IPDA detectors increases CARS derived temperatures \\/approx\\/3--6%. This error is partially offset by correcting for the perturbations in the N vibrational population resulting from

  15. Feasibility of MatriXX 2D detector array for HDR brachytherapy planning system assessment

    NASA Astrophysics Data System (ADS)

    Zeman, Jozef; Valenta, Jiri; Gabris, Frantisek; Grezdo, Jozef; Stastna, Simona

    2012-10-01

    IBA Dosimetry GmbH participated in the Joint Research Project 慖ncreasing cancer treatment efficacy using 3D brachytherapy as a non-funded partner in the work package which was mostly dedicated to the determination of dose-to-water distribution from a high-dose-rate (HDR) brachytherapy source. The dose distribution was measured with a MatriXX (MXX) 2D detector array and compared with Dose Cube Data, calculated by treatment planning systems (TPS). All measurements and calculations were performed in cooperation with OUSA, Bratislava and FNB, Prague. The comparison has been carried out for three irradiation geometries: single source position, single line and four line motions of the source, and with the effective point of measurement in a plane at 6 mm, 10 mm and 20 mm distance from the source position. The comparison of the MXX measurements and the TPS calculations was evaluated by the commercial IBA Dosimetry software OmniPro I'mRT (1) as the difference between maximum of measured and calculated values and (2) as the maximum difference between the two-dimensional distributions of measured and calculated values. The dose distribution was evaluated by the gamma method with parameters 3 mm and 3%. All differences of comparison of the MXX measurements and TPS calculations were within the range 10% and the ?-index was less than 1 for 96% (or 97%, respectively) of the dose distribution in the plane at 10 mm distance from the source position.

  16. Evolution of miniature detectors and focal plane arrays for infrared sensors

    NASA Technical Reports Server (NTRS)

    Watts, Louis A.

    1993-01-01

    Sensors that are sensitive in the infrared spectral region have been under continuous development since the WW2 era. A quest for the military advantage of 'seeing in the dark' has pushed thermal imaging technology toward high spatial and temporal resolution for night vision equipment, fire control, search track, and seeker 'homing' guidance sensing devices. Similarly, scientific applications have pushed spectral resolution for chemical analysis, remote sensing of earth resources, and astronomical exploration applications. As a result of these developments, focal plane arrays (FPA) are now available with sufficient sensitivity for both high spatial and narrow bandwidth spectral resolution imaging over large fields of view. Such devices combined with emerging opto-electronic developments in integrated FPA data processing techniques can yield miniature sensors capable of imaging reflected sunlight in the near IR and emitted thermal energy in the Mid-wave (MWIR) and longwave (LWIR) IR spectral regions. Robotic space sensors equipped with advanced versions of these FPA's will provide high resolution 'pictures' of their surroundings, perform remote analysis of solid, liquid, and gas matter, or selectively look for 'signatures' of specific objects. Evolutionary trends and projections of future low power micro detector FPA developments for day/night operation or use in adverse viewing conditions are presented in the following test.

  17. Combining transverse field detectors and color filter arrays to improve multispectral imaging systems.

    PubMed

    Mart韓ez, Miguel A; Valero, Eva M; Hern醤dez-Andr閟, Javier; Romero, Javier; Langfelder, Giacomo

    2014-05-01

    This work focuses on the improvement of a multispectral imaging sensor based on transverse field detectors (TFDs). We aimed to achieve a higher color and spectral accuracy in the estimation of spectral reflectances from sensor responses. Such an improvement was done by combining these recently developed silicon-based sensors with color filter arrays (CFAs). Consequently, we sacrificed the filter-less full spatial resolution property of TFDs to narrow down the spectrally broad sensitivities of these sensors. We designed and performed several experiments to test the influence of different design features on the estimation quality (type of sensor, tunability, interleaved polarization, use of CFAs, type of CFAs, number of shots), some of which are exclusive to TFDs. We compared systems that use a TFD with systems that use normal monochrome sensors, both combined with multispectral CFAs as well as common RGB filters present in commercial digital color cameras. Results showed that a system that combines TFDs and CFAs performs better than systems with the same type of multispectral CFA and other sensors, or even the same TFDs combined with different kinds of filters used in common imaging systems. We propose CFA+TFD-based systems with one or two shots, depending on the possibility of using longer capturing times or not. Improved TFD systems thus emerge as an interesting possibility for multispectral acquisition, which overcomes the limited accuracy found in previous studies. PMID:24921886

  18. Validated HPLC-Diode Array Detector Method for Simultaneous Evaluation of Six Quality Markers in Coffee.

    PubMed

    Gant, Anastasia; Leyva, Vanessa E; Gonzalez, Ana E; Maruenda, Helena

    2015-01-01

    Nicotinic acid, N-methylpyridinium ion, and trigonelline are well studied nutritional biomarkers present in coffee, and they are indicators of thermal decomposition during roasting. However, no method is yet available for their simultaneous determination. This paper describes a rapid and validated HPLC-diode array detector method for the simultaneous quantitation of caffeine, trigonelline, nicotinic acid, N-methylpyridinium ion, 5-caffeoylquinic acid, and 5-hydroxymethyl furfural that is applicable to three coffee matrixes: green, roasted, and instant. Baseline separation among all compounds was achieved in 30 min using a phenyl-hexyl RP column (250 4.6 mm, 5 ?m particle size), 0.3% aqueous formic buffer (pH 2.4)-methanol mobile phase at a flow rate of 1 mL/min, and a column temperature at 30癈. The method showed good linear correlation (r(2) > 0.9985), precision (less than 3.9%), sensitivity (LOD = 0.023-0.237 ?g/mL; LOQ = 0.069-0.711 ?g/mL), and recovery (84-102%) for all compounds. This simplified method is amenable for a more complete routine evaluation of coffee in industry. PMID:25857885

  19. Optofluidic holographic microscopy with custom field of view (FoV) using a linear array detector.

    PubMed

    Bianco, V; Paturzo, M; Marchesano, V; Gallotta, I; Di Schiavi, E; Ferraro, P

    2015-05-01

    Simple and effective imaging strategies are of utmost interest for applications on a lab-on-chip scale. In fact, the majority of diagnostic tools for medical as well as biotechnological studies still employ image-based approaches. Having onboard the chip a compact but powerful imaging apparatus with multiple imaging capabilities, such as 3D dynamic focusing along the optical axis, unlimited field of view (FoV) and double outputs, namely, intensity and quantitative phase-contrast maps of biological objects, is of extreme importance for the next generation of Lab-on-a-Chip (LoC) devices. Here we present a coherent 3D microscopy approach with a holographic modality that is specifically suitable for studying biological samples while they simply flow along microfluidic paths. The LoC device is equipped with a compact linear array detector to capture and generate a new conceptual type of a digital hologram in the space-time domain, named here as Space-Time Digital Hologram (STDH). The reported results show that the method is a promising diagnostic tool for optofluidic investigations of biological specimens. PMID:25832808

  20. Infrared thermal detector array using Eu(TTA)3-based temperature sensitive paint for optical readable thermal imaging device

    NASA Astrophysics Data System (ADS)

    Wang, Min; Tsukamoto, Takashiro; Tanaka, Shuji

    2015-03-01

    This paper presents the design and fabrication of an infrared (IR) thermal detector array made of Eu(TTA)3-based temperature sensitive paint (TSP). The TSP emits 610?nm visible luminescence depending on temperature, and works as an IR-to-visible converter. An optical readout system was designed to excite and observe the detector array using a 355?nm light-emitting diode (LED) and a charge-coupled-device (CCD) camera, respectively. The temperature coefficient of the TSP was measured to be ?1.58%?K?1, and thermal images of a 400?癈 object were successfully obtained. The noise analysis showed that the noise-equivalent temperature difference (NETD) of the imaging system was about 4.5?K.

  1. Breadboard linear array scan imager program

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The performance was evaluated of large scale integration photodiode arrays in a linear array scan imaging system breadboard for application to multispectral remote sensing of the earth's resources. Objectives, approach, implementation, and test results of the program are presented.

  2. Resonant-cavity avalanche photodiodes and narrow spectral response photodiodes

    Microsoft Academic Search

    K. A. Anselm; S. S. Murtaza; Ben G. Streetman; Joe C. Campbell

    1996-01-01

    The performance of conventional photodiodes is limited by an intrinsic tradeoff between quantum efficiency and bandwidth. We have successfully demonstrated that resonant-cavity photodiodes can simultaneously achieve high quantum efficiency and wide bandwidths. The resonant-cavity approach increases the absorption through multiple reflections between two parallel mirrors. In addition, the wavelength selective spectral response offers potential advantages for applications where filtering is

  3. High performance charge transfer device detectors

    SciTech Connect

    Sweedler, J.V.; Bilhorn, R.B.; Epperson, P.M.; Sims, G.R.; Denton, M.B.

    1988-02-15

    There is great interest in replacing single-channel photomultiplier tubes (PMTs) with multichannel devices (1,2). Multichannel detectors such as vidicons, intensified target vidicons, image dissectors, and photodiode arrays (PDAs) do not offer the sensitivity, dynamic range, and noise performance necessary to be competitive with the PMT in many situations. Successful application of these multichannel detectors is limited to experimental conditions in which the multichannel advantage outweighs the noise, cross talk, and dynamic-range disadvantages. New multichannel alternatives to PMT detection are now capable of superior sensitivity and dynamic range when compared on a detector element by detector element basis. In fact, some of these devices exceed the sensitivity and dynamic range of all other available detectors. The performance of charge transfer devices (CTDs) has advanced to the point where the application of this technology to the field of analytical chemistry is appropriate. In the first of this two-part series, the theory, design, operation, and performance of CTD detectors are described. CTDs are solid-state multichannel detectors. These detectors integrate signal information as light strikes them, much like photographic film. The amount of charge generated in a CTD detector is measured either by moving the charge form the detector element where it is collected to a charge-sensing amplifier, or by moving it within the detector element and measuring the voltage change induced by this movement.

  4. Miniature focal plane mass spectrometer with 1000-pixel modified-CCD detector array for direct ion measurement

    NASA Astrophysics Data System (ADS)

    Sinha, Mahadeva P.; Wadsworth, Mark

    2005-02-01

    A high performance, focal plane miniature mass spectrometer (MMS) of Mattauch-Herzog geometry with a CCD-based array detector for the direct and simultaneous measurements of different mass ions is described. Miniaturization (10cm5cm5cm,395g) was accomplished by using high-energy-product magnet material (Nd-B-Fe alloy) and a high permeability yoke material (V-Co-Fe Alloy) for the fabrication of the magnetic sector. The electrostatic sector was machined from a single piece of machinable ceramic (MACOR). All the components of the analyzer are mounted on a single plate, which facilitate their alignment and make the instrument rugged. The modified-CCD based ion detector array has 1000 elements (20?m2mm) and was invented in our laboratory. The photosensitive part of the CCD was replaced with a metal-oxide-semiconductor (MOS) capacitor for ion detection. The ion sensing capacitor plates are connected to the CCD gates that are operated in the fill-and spill mode providing a gain in the charge domain for the signal ions and minimizing various noises during measurements. The results reported in this article are the first application of this detector array for direct ion measurement and successfully prove the new technology. The MMS with the array detector can measure masses up to 250u with a unit mass resolution and expected to possess a sensitivity of detecting 5ions. The above attributes make MMS suitable for space applications for isotopic and chemical analysis and also for field applications on earth.

  5. FT-IR spectroscopic imaging microscopy of wheat kernels using a Mercury朇admium朤elluride focal-plane array detector

    Microsoft Academic Search

    Curtis Marcott; Robert C Reeder; Joseph A Sweat; Dia D Panzer; David L Wetzel

    1999-01-01

    A 6464 Mercury朇admium朤elluride (MCT) focal-plane array detector attached to a Fourier transform infrared (FT-IR) microscope was used to spectroscopically image 8-?m-thick cross-sections of wheat kernels in the fingerprint region of the infrared spectrum. After fast-Fourier transformation of the raw image interferograms, the data can be displayed as either a series of spectroscopic images collected at individual wavelengths, or as a

  6. A novel simultaneous unipolar multispectral integrated technology approach for HgCdTe IR detectors and focal plane arrays

    Microsoft Academic Search

    W. E. Tennant; M. Thomas; L. J. Kozlowski; W. V. McLevige; D. D. Edwall; M. Zandian; K. Spariosu; G. Hildebrand; V. Gil; P. Ely; M. Muzilla; A. Stoltz; J. H. Dinan

    2001-01-01

    In the last few years Rockwell has developed a novel simultaneous unipolar multispectral integrated HgCdTe detector and focal\\u000a plane array technology that is a natural and relatively straightforward derivative of our baseline double layer planar heterostructure\\u000a (DLPH) molecular beam epitaxial (MBE) technology. Recently this technology was awarded a U.S. patent. This simultaneous unipolar\\u000a multispectral integrated technology (SUMIT) shares the high

  7. Miniature focal plane mass spectrometer with 1000-pixel modified-CCD detector array for direct ion measurement

    SciTech Connect

    Sinha, Mahadeva P.; Wadsworth, Mark [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States); Tangent Technologies, Inc., Monrovia, California 91016 (United States)

    2005-02-01

    A high performance, focal plane miniature mass spectrometer (MMS) of Mattauch-Herzog geometry with a CCD-based array detector for the direct and simultaneous measurements of different mass ions is described. Miniaturization (10 cmx5 cmx5 cm,395 g) was accomplished by using high-energy-product magnet material (Nd-B-Fe alloy) and a high permeability yoke material (V-Co-Fe Alloy) for the fabrication of the magnetic sector. The electrostatic sector was machined from a single piece of machinable ceramic (MACOR). All the components of the analyzer are mounted on a single plate, which facilitate their alignment and make the instrument rugged. The modified-CCD based ion detector array has 1000 elements (20 {mu}mx2 mm) and was invented in our laboratory. The photosensitive part of the CCD was replaced with a metal-oxide-semiconductor (MOS) capacitor for ion detection. The ion sensing capacitor plates are connected to the CCD gates that are operated in the fill-and spill mode providing a gain in the charge domain for the signal ions and minimizing various noises during measurements. The results reported in this article are the first application of this detector array for direct ion measurement and successfully prove the new technology. The MMS with the array detector can measure masses up to 250 u with a unit mass resolution and expected to possess a sensitivity of detecting {approx}5 ions. The above attributes make MMS suitable for space applications for isotopic and chemical analysis and also for field applications on earth.

  8. Measuring extensive air showers with Cherenkov light detectors of the Yakutsk array: the energy spectrum of cosmic rays

    Microsoft Academic Search

    A. A. Ivanov; S. P. Knurenko; I. Ye. Sleptsov

    2009-01-01

    The energy spectrum of cosmic rays in the range E?1015 eV to 61019 eV is studied in this paper using air Cherenkov light detectors of the Yakutsk array. The total flux of photons produced by the relativistic electrons (including positrons as well, hereafter) of extensive air showers in the atmosphere is used as an energy estimator of the primary particle

  9. Measuring extensive air showers with Cherenkov light detectors of the Yakutsk array: the energy spectrum of cosmic rays

    Microsoft Academic Search

    A. A. Ivanov; S. P. Knurenko; I. Ye Sleptsov

    2009-01-01

    The energy spectrum of cosmic rays in the range E~1015 eV to 61019 eV is studied in this paper using air Cherenkov light detectors of the Yakutsk array. The total flux of photons produced by the relativistic electrons (including positrons as well, hereafter) of extensive air showers in the atmosphere is used as an energy estimator of the primary particle

  10. An evaluation to design high performance pinhole array detector module for four head SPECT: a simulation study

    NASA Astrophysics Data System (ADS)

    Rahman, Tasneem; Tahtali, Murat; Pickering, Mark R.

    2014-09-01

    The purpose of this study is to derive optimized parameters for a detector module employing an off-the-shelf X-ray camera and a pinhole array collimator applicable for a range of different SPECT systems. Monte Carlo simulations using the Geant4 application for tomographic emission (GATE) were performed to estimate the performance of the pinhole array collimators and were compared to that of low energy high resolution (LEHR) parallel-hole collimator in a four head SPECT system. A detector module was simulated to have 48 mm by 48 mm active area along with 1mm, 1.6mm and 2 mm pinhole aperture sizes at 0.48 mm pitch on a tungsten plate. Perpendicular lead septa were employed to verify overlapping and non-overlapping projections against a proper acceptance angle without lead septa. A uniform shape cylindrical water phantom was used to evaluate the performance of the proposed four head SPECT system of the pinhole array detector module. For each head, 100 pinhole configurations were evaluated based on sensitivity and detection efficiency for 140 keV ?-rays, and compared to LEHR parallel-hole collimator. SPECT images were reconstructed based on filtered back projection (FBP) algorithm where neither scatter nor attenuation corrections were performed. A better reconstruction algorithm development for this specific system is in progress. Nevertheless, activity distribution was well visualized using the backprojection algorithm. In this study, we have evaluated several quantitative and comparative analyses for a pinhole array imaging system providing high detection efficiency and better system sensitivity over a large FOV, comparing to the conventional four head SPECT system. The proposed detector module is expected to provide improved performance in various SPECT imaging.

  11. Three-dimensional array of scintillation crystals with proper reflector arrangement for a depth of interaction detector

    Microsoft Academic Search

    Narimichi Orita; Hideo Murayama; Hideyuki Kawai; Naoko Inadama; Tomoaki Tsuda

    2005-01-01

    A new method to acquire four-layer depth of interaction (DOI) information is proposed for the next generation positron emission tomography scanner (jPET-D4) that realizes high resolution and high sensitivity. The detector module of the jPET-D4 is a 16164 Gd2SiO5: Ce (GSO) multicrystal array coupled with a 256 ch flat panel position sensitive photomultiplier tube (256 ch FP-PMT) having large opening

  12. 1K X 1K Si:As IBC detector arrays for JWST MIRI and other applications

    Microsoft Academic Search

    Peter J. Love; Alan W. Hoffman; Nancy A. Lum; Ken J. Ando; William D. Ritchie; Neil J. Therrien; Andrew G. Toth; Roger S. Holcombe

    2004-01-01

    1K 1K Si:As Impurity Band Conduction (IBC) arrays have been developed by Raytheon Vision Systems (RVS) for the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI). The devices are also suitable for other low-background applications. The Si:As IBC detectors respond out to ~28 microns, covering an important mid-IR region beyond the 1-5 micron range covered by the JWST NIRCam

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

    SciTech Connect

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

    2012-05-15

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

  14. Retroreflector arrays for better light collection efficiency of ?-ray imaging detectors with continuous scintillation crystals without DOI misestimation

    NASA Astrophysics Data System (ADS)

    Ros, A.; Lerche, Ch W.; Sebastia, A.; Sanchez, F.; Benlloch, J. M.

    2014-04-01

    A method to improve light collection efficiency of ?-ray imaging detectors by using retroreflector arrays has been tested, simulations of the behaviour of the scintillation light illuminating the retroreflector surface have been made. Measurements including retroreflector arrays in the setup have also been taken. For the measurements, positron emission tomography (PET) detectors with continuous scintillation crystals have been used. Each detector module consists of a continuous LSO-scintillator of dimensions 49x49x10 mm3 and a H8500 position-sensitive photo-multiplier (PSPMT) from Hamamatsu. By using a continuous scintillation crystal, the scintillation light distribution has not been destroyed and the energy, the centroids along the x- and y-direction and the depth of interaction (DOI) can be estimated. Simulations have also been run taking into account the use of continuous scintillation crystals. Due to the geometry of the continuous scintillation crystals in comparison with pixelated crystals, a good light collection efficiency is necessary to correctly reconstruct the impact point of the ?-ray. The aim of this study is to investigate whether micro-machine retro-reflectors improve light yield without misestimation of the impact point. The results shows an improvement on the energy and centroid resolutions without worsening the depth of interaction resolution. Therefore it can be concluded that using retroreflector arrays at the entrance side of the scintillation crystal improves light collection efficiency without worsening the impact point estimation.

  15. Study of Ultra-High Energy Cosmic Ray Composition Using Telescope Array's Middle Drum Detector and Surface Array in Hybrid Mode

    E-print Network

    Abbasi, R U; Abu-Zayyad, T; Allen, M; Anderson, R; Azuma, R; Barcikowski, E; Belz, J W; Bergman, D R; Blake, S A; Cady, R; Chae, M J; Cheon, B G; Chiba, J; Chikawa, M; Cho, W R; Fujii, T; Fukushima, M; Goto, T; Hanlon, W; Hayashi, Y; Hayashida, N; Hibino, K; Honda, K; Ikeda, D; Inoue, N; Ishii, T; Ishimori, R; Ito, H; Ivanov, D; Jui, C C H; Kadota, K; Kakimoto, F; Kalashev, O; Kasahara, K; Kawai, H; Kawakami, S; Kawana, S; Kawata, K; Kido, E; Kim, H B; Kim, J H; Kitamura, S; Kitamura, Y; Kuzmin, V; Kwon, Y J; Lan, J; Lim, S I; Lundquist, J P; Machida, K; Martens, K; Matsuda, T; Matsuyama, T; Matthews, J N; Minamino, M; Mukai, Y; Myers, I; Nagasawa, K; Nagataki, S; Nakamura, T; Nonaka, T; Nozato, A; Ogio, S; Ogura, J; Ohnishi, M; Ohoka, H; Oki, K; Okuda, T; Ono, M; Oshima, A; Ozawa, S; Park, I H; Pshirkov, M S; Rodriguez, D C; Rubtsov, G; Ryu, D; Sagawa, H; Sakurai, N; Sampson, A L; Scott, L M; Shah, P D; Shibata, F; Shibata, T; Shimodaira, H; Shin, B K; Shin, H S; Smith, J D; Sokolsky, P; Springer, R W; Stokes, B T; Stratton, S R; Stroman, T; Suzawa, T; Takamura, M; Takeda, M; Takeishi, R; Taketa, A; Takita, M; Tameda, Y; Tanaka, H; Tanaka, K; Tanaka, M; Thomas, S B; Thomson, G B; Tinyakov, P; Tkachev, I; Tokuno, H; Tomida, T; Troitsky, S; Tsunesada, Y; Tsutsumi, K; Uchihori, Y; Udo, S; Urban, F; Vasiloff, G; Wong, T; Yamane, R; Yamaoka, H; Yamazaki, K; Yang, J; Yashiro, K; Yoneda, Y; Yoshida, S; Yoshiia, H; Zollinger, R; Zundel, Z

    2014-01-01

    Previous measurements of the composition of Ultra-High energy Cosmic Rays (UHECRs) made by the High Resolution Fly's Eye (HiRes) and Pierre Auger Observatory (PAO) are seemingly contradictory but utilize different detection methods, as HiRes was a stereo detector and PAO is a hybrid detector. The five year Telescope Array (TA) Middle Drum hybrid composition measurement is similar in methodology to PAO, and good agreement is evident between data and a light, largely protonic composition using simulations from a variety of hadronic models for the comparison of both elongation rate and shower fluctuations. This is in good agreement with the HiRes results. This analysis is presented using two methods: data cuts using simple geometrical variables and a new pattern recognition technique.

  16. Spitzer Space Telescope: Dark Current and Total Noise Prediction for InSb Detector Arrays in the Infrared Array Camera (IRAC) for the Post-Cryogen Era

    Microsoft Academic Search

    Craig W. McMurtry; Judith L. Pipher; William J. Forrest

    Duringtheexpected5+yearsofoperation,theSpitzerSpaceTelescopeisandwillcontinuetoproduceoutstand- inginfraredimagesandspectra,andgreatlyfurtherscientiflcunderstandingofouruniverse. TheSpitzerSpace Telescope's instruments are cryogenically cooled to achieve low dark current and low noise. After the cryogens are exhausted, the Spitzer Space Telescope will only be cooled by passively radiating into space. The detector arrays in the IRAC instrument are expected to equilibrate at approximately 30K. The two shortest wavelength channels(3.6 and4.5 micron)employ InSbdetectorarraysandareexpectedtofunction andperformwith only amodestdegradationinsensitivity. Thus,anextendedmissionispossibleforSpitzer.

  17. Low-energy nuclear radiation detection with a silicon photodiode

    Microsoft Academic Search

    Hisao Yamamoto; Satoru Hatakeyama; Toshiyuki Norimura; Takehiko Tsuchiya

    1989-01-01

    A radiation detector was fabricated from a commercial silicon photodiode, after removing its transparent cover cap and surface coating. The window thickness of the detector fabricated was evaluated to be 23 mug\\/cm2. The area of the depletion region was 13.2 mm2 and its depth was estimated to be about 100 mum. The energy resolution (FWHM) was 2.0 keV for conversion

  18. Investigation of avalanche photodiodes radiation hardness for baryonic matter studies

    E-print Network

    Kushpil, V; Ladygin, V P; Kugler, A; Kushpil, S; Svoboda, O; Tlust, P

    2015-01-01

    Modern avalanche photodiodes (APDs) with high gain are good device candidates for light readout from detectors applied in relativistic heavy ion collisions experiments. The results of the investigations of the APDs properties from Zecotek, Ketek and Hamamatsu manufacturers after irradiation using secondary neutrons from cyclotron facility U120M at NPI of ASCR in \\v{R}e\\v{z} are presented. The results of the investigations can be used for the design of the detectors for the experiments at NICA and FAIR.

  19. Infrared focal plane array based on MWIR\\/LWIR dual-band QWIPs: detector optimization and array properties

    Microsoft Academic Search

    Harald Schneider; Thomas Maier; Joachim Fleissner; Martin Walther; Peter Koidl; Gunter Weimann; Wolfgang Cabanski; Marcus Finck; Peter Menger; Werner Rode; Johann Ziegler

    2005-01-01

    Quantum well infrared photodetectors (QWIPs) have gained maturity for large focal plane arrays (FPA) with excellent thermal resolution, low 1\\/f noise, low fixed-pattern noise, and high pixel operability. Due to their spectrally narrow absorption, QWIPs are particularly suitable for thermal imaging applications involving several atmospheric transmission bands or several colors within the same band. We report on our progress on

  20. A 32-channel LSO matrix coupled to a monolithic 48 APD array for high resolution PET

    Microsoft Academic Search

    B. J. Pichler; G. Boening; M. Rafecas; W. Pimpl; M. Schwaiger; S. I. Ziegler

    2000-01-01

    Summary form only given as follows: Avalanche Photodiodes (APD) offer new design options for high resolution PET detectors. New, monolithic arrays of 48 densely packed APDs (each with a 1.6 mm1.6 mm sensitive area) were developed and evaluated for their suitability to read out 32 small (2 mm2 mm6 mm) LSO crystals. The gain of the APDs was about 10,