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1

An intensified photodiode array detector for space applications  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

2

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

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

3

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

SciTech Connect

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

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

4

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

SciTech Connect

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.

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

5

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

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–acetate–water buffer gradient elution system on a C18 column. The sample extraction data demonstrated that the single

Yuegang Zuo; Hao Chen; Yiwei Deng

2002-01-01

6

Determination of synthetic acaricides residues in beeswax by high-performance liquid chromatography with photodiode array detector.  

PubMed

A multiresidue HPLC method for identification and quantification of the synthetic acaricides fluvalinate, coumaphos, bromopropylate and its metabolite 4,4'-dibromobenzophenone in beeswax has been developed. Different techniques were tested and modified. The method consists of a sample preparation with isooctane followed by solid phase extraction using Florisil columns. Determination of the synthetic acaricides is achieved by HPLC with a photodiode array detector. Analytical performance of the proposed method, including sensitivity, accuracy and precision was satisfactory. The LOD for the analytes varied between 0.1 and 0.2 microg g(-1) wax and the recoveries between 70 and 110%. Relative standard deviation of the repeatability of the method is <15% and reproducibility is <31%. PMID:17386431

Adamczyk, Sabine; Lázaro, Regina; Pérez-Arquillué, Consuelo; Herrera, Antonio

2007-01-01

7

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

PubMed Central

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.

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

2014-01-01

8

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

ERIC Educational Resources Information Center

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…

Jones, Dianna G.

1985-01-01

9

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

E-print Network

, which have approximately 16 times the quantum efficiency of the MCP detector. Scattered light collection of the spectrum allows for more accurate detection of subtle changes in the distribution function, particularly has also been upgraded, allowing the radial viewing location of the TS system to be easily changed

Biewer, Theodore

10

Quantitative and Chemical Fingerprint Analysis for the Quality Evaluation of Isatis indigotica based on Ultra-Performance Liquid Chromatography with Photodiode Array Detector Combined with Chemometric Methods  

PubMed Central

A simple and reliable method of ultra-performance liquid chromatography with photodiode array detector (UPLC-PDA) was developed to control the quality of Radix Isatidis (dried root of Isatis indigotica) for chemical fingerprint analysis and quantitative analysis of eight bioactive constituents, including R,S-goitrin, progoitrin, epiprogoitrin, gluconapin, adenosine, uridine, guanosine, and hypoxanthine. In quantitative analysis, the eight components showed good regression (R > 0.9997) within test ranges, and the recovery method ranged from 99.5% to 103.0%. The UPLC fingerprints of the Radix Isatidis samples were compared by performing chemometric procedures, including similarity analysis, hierarchical clustering analysis, and principal component analysis. The chemometric procedures classified Radix Isatidis and its finished products such that all samples could be successfully grouped according to crude herbs, prepared slices, and adulterant Baphicacanthis cusiae Rhizoma et Radix. The combination of quantitative and chromatographic fingerprint analysis can be used for the quality assessment of Radix Isatidis and its finished products. PMID:22942750

Shi, Yan-Hong; Xie, Zhi-Yong; Wang, Rui; Huang, Shan-Jun; Li, Yi-Ming; Wang, Zheng-Tao

2012-01-01

11

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

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

Liang, Xianrui; Ma, Meiling; Su, Weike

2013-01-01

12

SIMULTANEOUS ANALYSIS OF VITAMIN C AND ASPIRIN IN ASPIRIN C EFFERVESCENT TABLETS BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY–PHOTODIODE ARRAY DETECTOR  

Microsoft Academic Search

High performance liquid chromatographic–photodiode array (HPLC–PDA) method has been employed for the simultaneous determination of vitamin C (ascorbic acid) and aspirin (acetylsalicylic acid) in aspirin C effervescent tablets. Chromatographic separation of ascorbic acid (AA) and acetylsalicylic acid (ASA) was performed by reversed–phase using Betasil C18 column with particle size of 3 µm, 150 mm × 4.6 mm I.D. Optimum separation was achieved in isocratic mode

Zeid Abdullah Alothman; Mohammad Rizwan Khan; M. Naushad; Ayman Abdul Ghfar; Saikh Mohammad Wabaidur

2012-01-01

13

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)

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.

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

2013-02-01

14

Modeling scintillator-photodiodes as detectors for megavoltage CT.  

PubMed

The use of cadmium tungstate (CdWO4) and cesium iodide [CsI(Tl)] scintillation detectors is studied in megavoltage computed tomography (MVCT). A model describing the signal acquired from a scintillation detector has been developed which contains two steps: (1) the calculation of the energy deposited in the crystal due to MeV photons using the EGSnrc Monte Carlo code; and (2) the transport of the optical photons generated in the crystal voxels to photodiodes using the optical Monte Carlo code DETECT2000. The measured detector signals in single CdWO4 and CsI(Tl) scintillation crystals of base 0.275 x 0.8 cm2 and heights 0.4, 1, 1.2, 1.6 and 2 cm were, generally, in good agreement with the signals calculated with the model. A prototype detector array which contains 8 CdWO4 crystals, each 0.275 x 0.8 x 1 cm3, in contact with a 16-element array of photodiodes was built. The measured attenuation of a Cobalt-60 beam as a function of solid water thickness behaves linearly. The frequency dependent modulation transfer function [MTF(f)], noise power spectrum [NPS(f)], and detective quantum efficiency [DQE(f)] were measured for 1.25 MeV photons (in a Cobalt-60 beam). For 6 MV photons, only the MTF(f) was measured from a linear accelerator, where large pulse-to-pulse fluctuations in the output of the linear accelerator did not allow the measurement of the NPS(f). A two-step Monte Carlo simulation was used to model the detector's MTF(f), NPS(f) and DQE(f). The DQE(0) of the detector array was found to be 26% and 19% for 1.25 MeV and 6 MV photons, respectively. For 1.25 MeV photons, the maximum discrepancies between the measured and modeled MTF(f), relative NPS(f) and the DQE(f) were found to be 1.5%, 1.2%, and 1.9%, respectively. For the 6 MV beam, the maximum discrepancy between the modeled and the measured MTF(f) was found to be 2.5%. The modeling is sufficiently accurate for designing appropriate detectors for MVCT. PMID:15191313

Monajemi, T T; Steciw, S; Fallone, B G; Rathee, S

2004-05-01

15

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

Microsoft Academic Search

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

Alexey Vert; Stanislav Soloviev; Alexander Bolotnikov; Peter Sandvik

2009-01-01

16

Photodiode arrays having minimized cross-talk between diodes  

DOEpatents

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.

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

2000-10-17

17

Multidirectional photodiode array for the measurement of solar radiances  

Microsoft Academic Search

An instrument designed to measure the angular variation of an incident radiance field is described. The instrument utilizes a multidetector design which views the incident radiance field from several angular positions simultaneously. A version of the instrument which utilized 13 silicon photodiode detectors has been constructed and used to collect data of interest to the meteorological community. The instrument was

J. M. Davis; C. Vogel; S. K. Cox

1982-01-01

18

Analytical high-speed countercurrent chromatography with photodiode array detection (HSCCC-UV)  

Microsoft Academic Search

The use of analytical high-speed countercurrent chromatography with a photodiode array detector (HSCCC-UV) is described. Reduction of detector noise caused by non-retained stationary phase was achieved by adding an auxiliary solvent (MeOH, isoPrOH) by means of a post-column reactor. The technique was applied to the separation of aromatic compounds and natural products in Hexane-MeOH-Hâ and CHClâ-MeOH-HâO solvent systems. On-line recorded

Schaufelberger

1989-01-01

19

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

SciTech Connect

We present measurements of a 4 element PET detector module that uses a 2{times}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{times}3{times}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 {open_quotes}lossy{close_quotes} 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{degrees}C with a photodiode amplifier peaking time of 2 {mu}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.

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

1994-11-01

20

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

SciTech Connect

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.

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

21

Pyroelectric detector arrays  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

22

Pyroelectric detector arrays  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

23

Large area silicon avalanche photodiodes for scintillation detectors  

NASA Astrophysics Data System (ADS)

Large area (?1 cm 2) silicon avalanche photodiodes (SiAPDs) have been fabricated and their performance as optical detectors for use with scintillating crystals has been measured. Light sensitivity is measured for hexagonal SiAPDs of 1.57 cm 2 total package area, and the energy and timing resolution is measured for these devices coupled to CsI(Tl) scintillators operating as gamma spectrometers.

Farrell, R.; Olschner, F.; Frederick, E.; McConchie, L.; Vanderpuye, K.; Squillante, M. R.; Entine, G.

1990-03-01

24

Large area silicon avalanche photodiodes for scintillation detectors  

Microsoft Academic Search

Large area (~1 cm2) silicon avalanche photodiodes (SiAPDs) have been fabricated and their performance as optical detectors for use with scintillating crystals has been measured. Light sensitivity is measured for hexagonal SiAPDs of 1.57 cm2 total package area, and the energy and timing resolution is measured for these devices coupled to CsI(Tl) scintillators operating as gamma spectrometers.

R. Farrell; F. Olschner; E. Frederick; L. McConchie; K. Vanderpuye; M. R. Squillante; G. Entine

1990-01-01

25

Organic light detectors: photodiodes and phototransistors.  

PubMed

While organic electronics is mostly dominated by light-emitting diodes, photovoltaic cells and transistors, optoelectronics properties peculiar to organic semiconductors make them interesting candidates for the development of innovative and disruptive applications also in the field of light signal detection. In fact, organic-based photoactive media combine effective light absorption in the region of the spectrum from ultraviolet to near-infrared with good photogeneration yield and low-temperature processability over large areas and on virtually every substrate, which might enable innovative optoelectronic systems to be targeted for instance in the field of imaging, optical communications or biomedical sensing. In this review, after a brief resume of photogeneration basics and of devices operation mechanisms, we offer a broad overview of recent progress in the field, focusing on photodiodes and phototransistors. As to the former device category, very interesting values for figures of merit such as photoconversion efficiency, speed and minimum detectable signal level have been attained, and even though the simultaneous optimization of all these relevant parameters is demonstrated in a limited number of papers, real applications are within reach for this technology, as it is testified by the increasing number of realizations going beyond the single-device level and tackling more complex optoelectronic systems. As to phototransistors, a more recent subject of study in the framework of organic electronics, despite a broad distribution in the reported performances, best photoresponsivities outperform amorphous silicon-based devices. This suggests that organic phototransistors have a large potential to be used in a variety of optoelectronic peculiar applications, such as a photo-sensor, opto-isolator, image sensor, optically controlled phase shifter, and opto-electronic switch and memory. PMID:23483718

Baeg, Kang-Jun; Binda, Maddalena; Natali, Dario; Caironi, Mario; Noh, Yong-Young

2013-08-21

26

Photon detection with high gain avalanche photodiode arrays  

Microsoft Academic Search

The detection of light emitted in fast scintillating fibers and Cerenkov radiators used for fiber calorimetry and tracking applications in high energy colliders, requires fast detector arrays with high sensitivity to short wavelength photons. Photomultiplier tubes, the traditional imaging detectors for short wavelength optical radiation, have limited spatial resolution and require expensive anti-magnetic shielding. We report on short wavelength sensitivity

S. Vasile; P. Gothoskar; R. Farrell; D. Sdrulla

1998-01-01

27

Scintillator-photodiode type detectors for multi-energy scanning introscopy  

E-print Network

Results of experimental studies of detector arrays S-PD (scintillator-photodiode) and PRD (scintillator-photoreceiving device) used for X-ray digital radiography have shown that there exist further possibilities to increase spatial resolution of this system up to 2-3 line pairs per mm. Theoretical analysis and experimental studies show that the two-energy detection method not only allows one to detect organics on the background of metal, but also substantially increases (by 3-5 times) the detection ability of the system as a whole, especially if parameters of the S-PD pair are optimized, in particular, when ZnSe(Te) is used in the low-energy circuit. A possibility to distinguish, in principle, between substances with insignificant differences in atomic number has been theoretically proven -- by transition to multi-energy radiography. 3D-imaging has been realized using S-PD detector arrays.

Ryzhikov, V D; Kozin, D N; Lisetskaya, E K; Opolonin, A D; Svishch, V M; Kulik, T V

2002-01-01

28

Scintillator-photodiode type detectors for multi-energy scanning introscopy  

E-print Network

Results of experimental studies of detector arrays S-PD (scintillator-photodiode) and PRD (scintillator-photoreceiving device) used for X-ray digital radiography have shown that there exist further possibilities to increase spatial resolution of this system up to 2-3 line pairs per mm. Theoretical analysis and experimental studies show that the two-energy detection method not only allows one to detect organics on the background of metal, but also substantially increases (by 3-5 times) the detection ability of the system as a whole, especially if parameters of the S-PD pair are optimized, in particular, when ZnSe(Te) is used in the low-energy circuit. A possibility to distinguish, in principle, between substances with insignificant differences in atomic number has been theoretically proven -- by transition to multi-energy radiography. 3D-imaging has been realized using S-PD detector arrays.

V. D. Ryzhikov; S. V. Naydenov; D. N. Kozin; E. K. Lisetskaya; A. D. Opolonin; V. M. Svishch; T. V. Kulik

2002-07-23

29

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

30

Avoiding sensor blindness in Geiger mode avalanche photodiode arrays fabricated in a conventional CMOS process  

NASA Astrophysics Data System (ADS)

The need to move forward in the knowledge of the subatomic world has stimulated the development of new particle colliders. However, the objectives of the next generation of colliders sets unprecedented challenges to the detector performance. The purpose of this contribution is to present a bidimensional array based on avalanche photodiodes operated in the Geiger mode to track high energy particles in future linear colliders. The bidimensional array can function in a gated mode to reduce the probability to detect noise counts interfering with real events. Low reverse overvoltages are used to lessen the dark count rate. Experimental results demonstrate that the prototype fabricated with a standard HV-CMOS process presents an increased efficiency and avoids sensor blindness by applying the proposed techniques.

Vilella, E.; Diéguez, A.

2011-12-01

31

Analytical high-speed countercurrent chromatography with photodiode array detection (HSCCC-UV)  

SciTech Connect

The use of analytical high-speed countercurrent chromatography with a photodiode array detector (HSCCC-UV) is described. Reduction of detector noise caused by non-retained stationary phase was achieved by adding an auxiliary solvent (MeOH, isoPrOH) by means of a post-column reactor. The technique was applied to the separation of aromatic compounds and natural products in Hexane-MeOH-H{sub 2} and CHCl{sub 3}-MeOH-H{sub 2}O solvent systems. On-line recorded UV spectra were almost identical to those obtained with pure standards in methanol. Spectra obtained by HSCCC-UV can be used to characterize separated compounds and facilitate peak identification.

Schaufelberger, D.E. (Chemical Synthesis and Analysis Lab., National Cancer Institute, Frederick Center Research Facility, Frederick, MD (US))

1989-01-01

32

Nano-multiplication region avalanche photodiodes and arrays  

NASA Technical Reports Server (NTRS)

An avalanche photodiode with a nano-scale reach-through structure comprising n-doped and p-doped regions, formed on a silicon island on an insulator, so that the avalanche photodiode may be electrically isolated from other circuitry on other silicon islands on the same silicon chip as the avalanche photodiode. For some embodiments, multiplied holes generated by an avalanche reduces the electric field in the depletion region of the n-doped and p-doped regions to bring about self-quenching of the avalanche photodiode. Other embodiments are described and claimed.

Zheng, Xinyu (Inventor); Pain, Bedabrata (Inventor); Cunningham, Thomas J. (Inventor)

2011-01-01

33

Solid state neutron detector array  

DOEpatents

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.

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

1999-08-17

34

Solid state neutron detector array  

DOEpatents

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.

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

35

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

NASA Astrophysics Data System (ADS)

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.

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

2013-01-01

36

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

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

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

37

X-ray imaging sensor arrays on foil using solution processed organic photodiodes and organic transistors  

NASA Astrophysics Data System (ADS)

We demonstrate organic imaging sensor arrays fabricated on flexible plastic foil with the solution processing route for both photodiodes and thin film transistors. We used the photovoltaic P3HT:PCBM blend for fabricating the photodiodes using spin coating and pentacene as semiconductor material for the TFTs. Photodiodes fabricated with P3HT:PCBM absorb in the green part of the visible spectrum which matches with the typical scintillator output wavelength. The arrays consist of 32x32 pixels with variation in pixel resolution of 200?mx200?m, 300?mx300?m and of 1mmx1mm. The accurate reproducibility of shadow images of the objects demonstrates the potential of these arrays for imaging purposes. We also demonstrate that the crosstalk is relatively insignificant despite the fact that the active photodiode forms a continuous layer in the array. Since both photodiodes and TFTs are made of organic material, they are processed at low temperatures below 150°C on foil which means that these imaging sensors can be flexible, light weight and low cost when compared to conventional amorphous silicon based imaging sensors on rigid substrates. In combination with a scintillator on top of the arrays, we show the potential of these arrays for the X-ray imaging applications.

Kumar, Abhishek; Moet, Date; van der Steen, Jan-Laurens; Tripathi, Ashutosh; Rodriguez, Francisco G.; Maas, Joris; Simon, Matthias; Reutten, Walter; Douglas, Alexander; Raaijmakers, Rob; Malinowski, Pawel E.; Myny, Kris; Shafique, Umar; Andriessen, Ronn; Heremans, Paul; Gelinck, Gerwin

2014-05-01

38

Crosstalk analysis of integrated Geiger-mode avalanche photodiode focal plane arrays  

E-print Network

Arrays of photon-counting Geiger-mode avalanche photodiodes (APDs) sensitive to 1.06 and 1.55 µm wavelengths and as large as 256 x 64 elements on 50 µm pitch have been fabricated for defense applications. As array size, ...

Younger, Richard D.

39

Advanced UV Detectors and Detector Arrays  

NASA Technical Reports Server (NTRS)

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.

Pankove, Jacques I.; Torvik, John

1998-01-01

40

64-element photodiode array for scintillation detection of x-rays  

NASA Astrophysics Data System (ADS)

The paper presents the design, technology and parameters of a new, silicon 64-element linear photodiode array developed at the Institute of Electron Technology (ITE) for the detection of scintillations emitted by CsI scintillators (??550 nm). The arrays are used in a device for examining the content of containers at border crossings under development at the National Centre for Nuclear Research. Two arrays connected with a scintillator block (128 CsI scintillators) form a 128-channel detection module. The array consists of 64 epiplanar photodiode structures (5.1 × 7.2 mm) and a 5.3 mm module. p+-?-n+ photodiode structures are optimised for the detection of radiation of ?? 550 nm wavelength with no voltage applied (photovoltaic mode). The structures are mounted on an epoxy-glass laminate substrate, copper-clad on both sides, on which connections with a common anode and separate cathode leads are located. The photosensitive surface of photodiodes is covered with a special silicone gel, which protects photodiodes against the mechanical impact of scintillators

Wegrzecki, Maciej; Wolski, Dariusz; Bar, Jan; Budzy?ski, Tadeusz; Ch?opik, Arkadiusz; Grabiec, Piotr; K?os, Helena; Panas, Andrzej; Piotrowski, Tadeusz; S?ysz, Wojciech; Stolarski, Maciej; Szmigiel, Dariusz; Wegrzecka, Iwona; Zaborowski, Micha?

2014-08-01

41

Using Photodiodes in the Laboratory.  

ERIC Educational Resources Information Center

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)

Jenkins, T. E.

1995-01-01

42

Demonstration of 4H-SiC avalanche photodiodes linear array  

Microsoft Academic Search

4H-SiC visible blind avalanche photodiode (APD) linear arrays have been fabricated and successfully tested. A 40 pixel linear array with only one bad pixel has been demonstrated. The linear arrays show uniform breakdown voltage and low leakage current. The photoresponse and the excess noise factor of 4H-SiC APD pixels have been studied. A very high multiplication gain with very low

F. Yan; C Qin; J. H Zhao; M Bush; G Olsen; B. K Ng; J. P. R David; R. C Tozer; M Weiner

2003-01-01

43

Demonstration of 4H-SiC avalanche photodiodes linear array  

NASA Astrophysics Data System (ADS)

4H-SiC visible blind avalanche photodiode (APD) linear arrays have been fabricated and successfully tested. A 40 pixel linear array with only one bad pixel has been demonstrated. The linear arrays show uniform breakdown voltage and low leakage current. The photoresponse and the excess noise factor of 4H-SiC APD pixels have been studied. A very high multiplication gain with very low excess noise factors is reported.

Yan, F.; Qin, C.; Zhao, J. H.; Bush, M.; Olsen, G.; Ng, B. K.; David, J. P. R.; Tozer, R. C.; Weiner, M.

2003-02-01

44

Medical Physics, Volume 11, No. 3 1984 , Pages 303310 A photodiode array x-ray imaging system for digital  

E-print Network

Medical Physics, Volume 11, No. 3 1984 , Pages 303­310 A photodiode array x-ray imaging system-noise x-ray images to detect low-contrast structure is described. The system makes use of a 1024-element, self-scanning, photodiode array Reticon RL 1024S optically coupled to an x-ray image intensifier tube

Cunningham, Ian

45

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

NASA Astrophysics Data System (ADS)

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.

Howard, Steven G.

1998-11-01

46

Massively Parallel MRI Detector Arrays  

PubMed Central

Originally proposed as a method to increase sensitivity by extending the locally high-sensitivity of small surface coil elements to larger areas, 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

Keil, Boris; Wald, Lawrence L

2013-01-01

47

A bench-top megavoltage fan-beam CT using CdWO4-photodiode detectors. I. System description and detector characterization.  

PubMed

We describe the components of a bench-top megavoltage computed tomography (MVCT) scanner that uses an 80-element detector array consisting of CdWO4 scintillators coupled to photodiodes. Each CdWO4 crystal is 2.75 x 8 x 10 mm3. The detailed design of the detector array, timing control, and multiplexer are presented. The detectors show a linear response to dose (dose rate was varied by changing the source to detector distance) with a correlation coefficient (R2) nearly unity with the standard deviation of signal at each dose being less than 0.25%. The attenuation of a 6 MV beam by solid water measured by this detector array indicates a small, yet significant spectral hardening that needs to be corrected before image reconstruction. The presampled modulation transfer function is strongly affected by the detector's large pitch and a large improvement can be obtained by reducing the detector pitch. The measured detective quantum efficiency at zero spatial frequency is 18.8% for 6 MV photons which will reduce the dose to the patient in MVCT applications. The detector shows a less than a 2% reduction in response for a dose of 24.5 Gy accumulated in 2 h; however, the lost response is recovered on the following day. A complete recovery can be assumed within the experimental uncertainty (standard deviation <0.5%); however, any smaller permanent damage could not be assessed. PMID:16696485

Rathee, S; Tu, D; Monajemi, T T; Rickey, D W; Fallone, B G

2006-04-01

48

Potential of high-performance liquid chromatography with photodiode array detection in forensic toxicology  

Microsoft Academic Search

The potentials and limitations of high-performance liquid chromatography-photodiode array detection are highlighted in respect to its use in the analysis of different biological matrices followed by the identification of unknowns. The logical analytical approach used in clinical and forensic toxicology, vital for the identification of one or more toxic substances as a cause of intoxication, is largely based on both

Willy E. Lambert; Jan F. Van Bocxlaer; André P. De Leenheer

1997-01-01

49

High resolution interrogation technique based on linear photodiode array spectrometer for fiber Bragg grating sensors  

Microsoft Academic Search

A linear photodiode array spectrometer based, high resolution interrogation technique for fiber Bragg grating sensors is demonstrated. Spline interpolation and Polynomial Approximation Algorithm (PAA) are applied to the data points acquired by the spectrometer to improve the original PAA based interrogation method. Thereby fewer pixels are required to achieve the same resolution as original. Theoretical analysis indicates that if the

Songwei Zhang; Yuliang Liu; Fang Li

2007-01-01

50

Avalanche photodiode array sensor with high-speed CCD delay line readout  

Microsoft Academic Search

A prototype solid-state multi-chip-module (MCM) optical sensor circuit is described. The MCM is designed to sample the optical signals from a fiber-optic array at rates up to 200 MHz. The fiber-optic inputs interface to the MCM avalanche-photodiode (APD) sensor array. The prototype 40 pixel MCM stores approximately 1000 samples from each fiber before readout. This is done on the MCM

Kevin L. Albright; Jeffrey M. Bradley

1999-01-01

51

Detector array with improved spatial resolution for digital radiographic system  

NASA Astrophysics Data System (ADS)

The film radiographic inspection remains among the most reliable methods for inspection of pipelines and metalwares. The worldwide trend of transition from film radiography to digital radiography requires creation of advanced digital radiography systems. The main direction of digital radiography systems development is improvement of spatial resolution. The pixel size of the X-ray film is several microns, while solid-state detector pixels have dimensions of several hundred or several thousand microns. For the most common detectors of "scintillator-photodiode" type, it is impossible in principle to obtain the film pixel sizes. However, the detecting ability for substances that differ by their density and atomic number achieved using "scintillator-photodiode" detectors is by several orders higher. Using a standard experiment scheme with dual-energy detector arrays, our aim was to show that it could be possible to substantially increase the accuracy of supervision of the inspected object. For obtaining shadow X-ray images, a receiving-detecting circuit with a detector array was developed for 200 mm scanning field. Using model digital radiographic systems and standard testing we have evaluated spatial resolution (not worse than 1.25 line pairs/mm) and detecting ability (better than 0.2 mm steel wire behind 6 mm steel).

Ryzhikov, Volodymyr D.; Opolonin, Oleksandr D.; Galkin, Serhiy M.; Volkov, Volodymyr G.; Lysetska, Olena K.; Kostioukevitch, Serhiy A.

2011-09-01

52

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

PubMed

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 µg ml(-1), with correlation coefficients >0.9999. Recoveries of the dye parts in aluminum lake dyes (spiked at levels of 1, 5, 25 µg 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 µg g(-1), respectively. This method was successfully applied in real samples of chewing gum. PMID:21707267

Yang, Yi; Yin, Jie; Shao, Bing

2011-09-01

53

Analysis of alkaloids in Coptis chinensis Franch by accelerated solvent extraction combined with ultra performance liquid chromatographic analysis with photodiode array and tandem mass spectrometry detections  

Microsoft Academic Search

A new method based on accelerated solvent extraction (ASE) followed by ultra performance liquid chromatography (UPLC) analysis has been developed for the identification and quantification of major alkaloids in extracts of Coptis chinensis Franch. The UPLC system consisted of a dual detection system of photodiode array detector (PDA) and positive ion electrospray ionization-tandem mass spectrometry (ESI-MS\\/MS) in sequential configuration. The

Junhui Chen; Fengmei Wang; Jie Liu; Frank Sen-Chun Lee; Xiaoru Wang; Huanghao Yang

2008-01-01

54

Design studies of a high resolution PET detector using APD arrays  

Microsoft Academic Search

The authors evaluated a compact, high resolution PET detector module using avalanche photodiode (APD) arrays to replace bulky position sensitive PMTs. The newly developed APD array is a planar processed 4×4 array which has a 2×2 mm2 pixel size with 0.4 mm gaps between pixels, about 60% quantum efficiency at 420 nm wavelength, and uniform high gain (>1000) across all

Y. Shao; R. W. Silverman; R. Farrell; L. Cirignano; R. Grazioso; K. S. Shah; G. Vissel; M. Clajus; T. O. Tumer; S. R. Cherry

2000-01-01

55

A liquid-helium cooled large-area silicon PIN photodiode x-ray detector  

E-print Network

An x-ray detector using a liquid-helium cooled large-area silicon PIN photodiode has been developed along with a tailor-made charge sensitive preamplifier whose first-stage JFET has been cooled. The operating temperature of the JFET has been varied separately and optimized. The x- and $\\gamma$-ray energy spectra for an \

Yoshizumi Inoue; Shigetaka Moriyama; Hideyuki Hara; Makoto Minowa; Fumio Shimokoshi

1995-04-27

56

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

NASA Astrophysics Data System (ADS)

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.

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

57

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

PubMed

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

Abel, Tobias; Sagmeister, Martin; Lamprecht, Bernhard; Kraker, Elke; Köstler, Stefan; Ungerböck, Birgit; Mayr, Torsten

2012-12-01

58

Reliability of InGaAs detectors and arrays  

NASA Astrophysics Data System (ADS)

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.

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

1992-02-01

59

Low temperature aSi:H photodiodes and flexible image sensor arrays patterned by digital lithography  

Microsoft Academic Search

Hydrogenated amorphous silicon-based image sensor arrays were fabricated on polyethylene naphthalate substrates, with photodiodes optimized for process temperatures of 150 °C. 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

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

2007-01-01

60

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

NASA Astrophysics Data System (ADS)

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 mm×3.0 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.

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

2009-10-01

61

Stressed detector arrays for airborne astronomy  

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

62

A new silicon avalanche photodiode photon counting detector module for astronomy  

Microsoft Academic Search

A new silicon avalanche photodiode photon counting detector module with a peak detection efficiency of 45 percent and a maximum counting rate of more than 3,000,000 cts\\/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 350-150 nm and

N. S. Nightingale

1991-01-01

63

Linear charge coupled device detector array for imaging light propagating in an integrated thin-film optical waveguide  

NASA Technical Reports Server (NTRS)

Device design, fabrication, and operation of a linear charge coupled device (CCD) detector array integrated with a thin film optical waveguide and applications of this structure to integrated optical signal processing and fiber optical communications were discussed. A two phase, overlapping-gate CCD is connected in parallel by means of a series of gates to an array of photodiodes. The photodiode provides an electrode free surface region so that a highly efficient waveguide detector coupling technique can be implemented. A thermally-oxidized layer of SiO2 forms an effective substrate for the optical waveguide.

Chen, C. L.; Boyd, J. T.

1976-01-01

64

Monolithic detector array comprised of >1000 aerial image sensing elements  

NASA Astrophysics Data System (ADS)

A monolithically integrated multi-element photodiode array with 7749 discrete detectors has been fabricated where each sensing element is equipped with a sampling aperture to allow for aerial image measurements with high spatial precision in the focal plane of lithographic lenses. As currently configured, any one of seven 1107-element linear arrays can be used at a given time to allow sampling across the long axis of a scanner lens. The individual elements are located 24 microns apart and are broken down into 27 sets of 41 distinctly different aperture types, with each set spaced 1 mm apart. In addition, the sampling apertures on the device are small enough to allow the device to act as a polarization sensor with high (<50 microns) spatial resolution. The high speed analog output amplifier allows for complete 1107-element images to be obtained at the full repetition rate of lithographic lasers (2KHz).

Kunz, Roderick R.; Rathman, Dennis D.; Spector, Steven J.; Yeung, Michael S.

2003-06-01

65

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

NASA Astrophysics Data System (ADS)

Hydrogenated amorphous silicon-based image sensor arrays were fabricated on polyethylene naphthalate substrates, with photodiodes optimized for process temperatures of 150°C. 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 180×180pixels and with sensitivity of 1.2pW/cm2.

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

2007-08-01

66

Geiger-mode avalanche photodiode focal plane arrays for three-dimensional imaging LADAR  

NASA Astrophysics Data System (ADS)

We report on the development of focal plane arrays (FPAs) employing two-dimensional arrays of InGaAsP-based Geiger-mode avalanche photodiodes (GmAPDs). These FPAs incorporate InP/InGaAs(P) Geiger-mode avalanche photodiodes (GmAPDs) to create pixels that detect single photons at shortwave infrared wavelengths with high efficiency and low dark count rates. GmAPD arrays are hybridized to CMOS read-out integrated circuits (ROICs) that enable independent laser radar (LADAR) time-of-flight measurements for each pixel, providing three-dimensional image data at frame rates approaching 200 kHz. Microlens arrays are used to maintain high fill factor of greater than 70%. We present full-array performance maps for two different types of sensors optimized for operation at 1.06 ?m and 1.55 ?m, respectively. For the 1.06 ?m FPAs, overall photon detection efficiency of >40% is achieved at <20 kHz dark count rates with modest cooling to ~250 K using integrated thermoelectric coolers. We also describe the first evalution of these FPAs when multi-photon pulses are incident on single pixels. The effective detection efficiency for multi-photon pulses shows excellent agreement with predictions based on Poisson statistics. We also characterize the crosstalk as a function of pulse mean photon number. Relative to the intrinsic crosstalk contribution from hot carrier luminescence that occurs during avalanche current flows resulting from single incident photons, we find a modest rise in crosstalk for multi-photon incident pulses that can be accurately explained by direct optical scattering.

Itzler, Mark A.; Entwistle, Mark; Owens, Mark; Patel, Ketan; Jiang, Xudong; Slomkowski, Krystyna; Rangwala, Sabbir; Zalud, Peter F.; Senko, Tom; Tower, John; Ferraro, Joseph

2010-09-01

67

Si:As BIB detector arrays  

NASA Technical Reports Server (NTRS)

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.

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

1986-01-01

68

Astronomical imaging with infrared array detectors  

Microsoft Academic Search

Advances in astronomy which have resulted from the use of IR-sensitive two-dimensional array detectors are reviewed. The technological aspects of IR array detectors are discussed. Observations of star formation regions, planetary nebulae, the Galactic center, activity in other galaxies, and the collision of two galaxies are examined. Pictures illustrating IR imagery from various observatories are presented.

Ian Gatley; D. L. Depoy; A. M. Fowler

1988-01-01

69

Integration of a concentric five element InAIAs/InGaAs avalanche photodiode array in a stabilized bi-static optical assembly  

NASA Astrophysics Data System (ADS)

In free space optical communication, photodetectors serve not only as communications receivers but as position sensitive detectors (PSD) for pointing, tracking, and stabilization. Typically, two separate detectors are utilized to perform these tasks but recent advances in the fabrication and development of large area, low noise avalanche photodiode (APD) arrays have enabled these devices to be used both as PSDs and as data communication receivers. This combined functionality allows for more flexibility and simplicity in optical assembly design without sacrificing the sensitivity and bandwidth performance of smaller, single element data receivers. This work presents a large area, five element concentric avalanche photodiode array rated for bandwidths beyond 1GHz with a measured carrier ionization ratio of approximately 0.2 at moderate APD gains. We discuss the integration of this array in a bi-static optical interrogator where it acts as a data receiver and provides position information for pointing and stabilization. In addition to front-end and digital electronics design, we also describe the optical assembly design and the development of a pointing and stabilization algorithm.

Ferraro, Mike S.; Mahon, Rita; Rabinovich, William S.; Murphy, James L.; Freeman, Wade T.; Frawley, Steve; Goetz, Peter G.; Burris, Harris R.; Thomas, Linda M.; Clark, William R.; Waters, William D.; Vaccaro, Kenneth; Krejca, Brian; Mathieu, Barry M.

2014-06-01

70

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

NASA Technical Reports Server (NTRS)

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.

Kenimer, R. L.

1988-01-01

71

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

DOEpatents

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.

Strauss, C.E.

1997-11-18

72

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

DOEpatents

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.

Strauss, Charlie E. (Santa Fe, NM)

1997-01-01

73

Thermopile Detector Arrays for Space Science Applications  

NASA Technical Reports Server (NTRS)

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.

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

74

Type-II InAs/GaSb photodiodes and focal plane arrays aimed at high operating temperatures  

NASA Astrophysics Data System (ADS)

Recent efforts to improve the performance of type II InAs/GaSb superlattice photodiodes and focal plane arrays (FPA) have been reviewed. The theoretical bandstructure models have been discussed first. A review of recent developments in growth and characterization techniques is given. The efforts to improve the performance of MWIR photodiodes and focal plane arrays (FPAs) have been reviewed and the latest results have been reported. It is shown that these improvements has resulted in background limited performance (BLIP) of single element photodiodes up to 180 K. FPA shows a constant noise equivalent temperature difference (NEDT) of 11 mK up to 120 K and it shows human body imaging up to 170 K.

Razeghi, M.; Abdollahi Pour, S.; Huang, E. K.; Chen, G.; Haddadi, A.; Nguyen, B. M.

2011-09-01

75

Seamless tiling of amorphous silicon photodiode-TFT arrays for very large area X-ray image sensors [digital radiography  

Microsoft Academic Search

The authors propose a method for producing a truly seamless tiled image sensor from four identical subarrays, such that the resulting tiled image sensor has no missing pixels. Four standard amorphous silicon photodiode-TFT (thin film transistor) arrays are cut parallel to the busbars, in the space between the bus-bar and the preceding pixel electrode. The cut is done in such

M. J. Powell; J. R. Hughes; N. C. Bird; C. Glasse; T. R. King

1998-01-01

76

Synchronous Photodiode-Signal Sampler  

NASA Technical Reports Server (NTRS)

Synchronous sampling circuit increases signal-to-noise ratio of measurements of chopped signal of known phase and frequency in presence of low-frequency or dc background noise. Used with linear array of photoelectric sensors for locating edge of metal plate. Multiplexing circuit cycles through 16 light-emitting-diode/photodiode pairs, under computer control. Synchronized with multiplexer so edge detector makes one background-subtracted signal measurement per emitter/detector pair in turn.

Primus, Howard K.

1988-01-01

77

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

SciTech Connect

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.

Suzuki, C.; Peterson, B.J.; Ida, K. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan)

2004-10-01

78

Nondestructive assessment of internal quality of Gannan navel orange by photodiode array spectrometer  

NASA Astrophysics Data System (ADS)

The photodiode array (PDA) spectrometer combined with partial least square (PLS) was developed to rapid measure the internal quality indices of Gannan navel orange nondestructively in the wavelength range of 550-950nm. The original spectra were processed by standard normal variate (SNV) and Savitzky-Golay (SG) smooth method. The optimal models of internal quality indices were determined after different spectral windows chosen. The optimal model of soluble solids content (SSC), total acidity (TA) and ratio of them were developed with RMSECV = 0.5118Brix%, 0.0856% and 2.0617 by PLS method, respectively. The optimal spectral windows were 700-950nm, 600-750nm and 600-950nm for measuring internal indices nondestructively by PDA. The results illustrated that PDA with PLS method were a rapid tool to measure the internal quality indices of Gannan navel orange nondestructively.

Sun, Xudong; Zhou, Huamao; Zhou, Wenchao; Liu, Yande

2008-12-01

79

1 16 Pt\\/4H-SiC Schottky Photodiode Array for Low-Level EUV and UV Spectroscopic Detection  

Microsoft Academic Search

This letter reports on a 1 times 16 Pt\\/4H-SiC Schottky photodiode array with a total detection area of 136.5 mm2 operating at the wavelength from 400 nm down to 7.5 nm. The array has an ultra low leakage current of 6.4 and 51 fA at -0.4 and -5 V, respectively. In the vacuum ultraviolet (UV) range from 200 nm down

Jun Hu; Xiaobin Xin; Charles L. Joseph; Xueqing Li; Jian H. Zhao

2008-01-01

80

High-speed bridge circuit for InGaAs avalanche photodiode single-photon detector  

NASA Astrophysics Data System (ADS)

Because of low power consumption and small footprint, avalanche photodiodes (APD) have been commonly applied to photon detection. Recently, high speed quantum communication has been demonstrated for high bit-rate quantum key distribution. For the high speed quantum communication, photon detectors should operate at GHz-clock frequencies. We propose balanced detection circuits for GHz-clock operation of InGaAs-APD photon detectors. The balanced single photon detector operates with sinusoidal wave gating. The sinusoidal wave appearing in the output is removed by the subtraction from APD signal without sharp band-elimination filters. Omission of the sharp filters removes the constraint on the operating frequency of the single photon detector. We present two designs, one works with two identical APDs, the other with one APD and a low-pass filter. The sinusoidal gating enables to eliminate the gating noise even with the simple configuration of the latter design. We demonstrated the balanced single photon detector operating with 1.020GHz clock at 233 K, 193 K, and 186.5 K. The dark count probability was 4.0 x 10-4 counts/pulse with the quantum efficiency of 10% at 233K, and 1.6 x 10-4 counts/pulse at 186.5 K. These results were obtained with easily available APDs (NR8300FP-C.C, RENESASS) originally developed for optical time-domain reflectmeters.

Hashimoto, Hirofumi; Tomita, Akihisa; Okamoto, Atsushi

2014-02-01

81

High-resolution ionization detector and array of such detectors  

DOEpatents

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.

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

2001-01-16

82

Determination of nitroaromatic explosives and their degradation products in unsaturated-zone water samples by high-performance liquid chromatography with photodiode-array, mass spectrometric, and tandem mass spectrometric detection  

USGS Publications Warehouse

Mass spectrometry and tandem mass spectrometry, coupled by a thermospray interface to a high-performance liguid chromatography system and equipped with a photodiode array detector, were used to determine the presence of nitroaromatic explosives and their degradation products in USA unsaturated-zone water samples. Using this approach, the lower limits of quantitation for explosives determined by mass spectrometry in this study typically ranged from 10 to 100 ng/l.

Gates, P. M.; Furlong, E. T.; Dorsey, T. F.; Burkhardt, M. R.

1996-01-01

83

Monolithic short wave infrared (SWIR) detector array  

NASA Technical Reports Server (NTRS)

A monolithic self-scanned linear detector array was developed for remote sensing in the 1.1- 2.4-micron spectral region. A high-density IRCCD test chip was fabricated to verify new design approaches required for the detector array. The driving factors in the Schottky barrier IRCCD (Pdsub2Si) process development are the attainment of detector yield, uniformity, adequate quantum efficiency, and lowest possible dark current consistent with radiometric accuracy. A dual-band module was designed that consists of two linear detector arrays. The sensor architecture places the floating diffusion output structure in the middle of the chip, away from the butt edges. A focal plane package was conceptualized and includes a polycrystalline silicon substrate carrying a two-layer, thick-film interconnecting conductor pattern and five epoxy-mounted modules. A polycrystalline silicon cover encloses the modules and bond wires, and serves as a radiation and EMI shield, thermal conductor, and contamination seal.

1983-01-01

84

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

Microsoft Academic Search

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.,

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

85

Array of germanium detectors for nuclear safeguards  

SciTech Connect

Our gamma-ray spectrometer system, designed for field use, offers high efficiency and high resolution for safeguards applications. The system consists of three 40% high-purity germanium detectors and a LeCroy 3500 data-acquisition system that calculates a composite spectrum for the three detectors. The LeCroy 3500 mainframe can be operated remotely from the detector array with control exercised through moderns and the telephone system. System performance with a mixed source of /sup 125/Sb, /sup 154/Eu, and /sup 155/Eu confirms the expected efficiency of 120% with an overall resolution that is between the resolution of the best detector and that of the worst.

Moss, C.E.; Bernard, W.; Dowdy, E.J.; Garcia, C.; Lucas, M.C.; Pratt, J.C.

1983-01-01

86

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

PubMed

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°C 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

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

2013-02-01

87

Initial characterization of a BGO-photodiode detector for high resolution positron emission tomography  

SciTech Connect

Spatial resolution in positron emission tomography is currently limited by the resolution of the detectors. This work presents the initial characterization of a detector design using small bismuth germanate (BGO) crystals individually coupled to silicon photodiodes (SPDs) for crystal identification, and coupled in groups to phototubes (PMTs) for coincidence timing. A 3 mm x 3 mm x 3 mm BGO crystal coupled only to an SPD can achieve a 511 keV photopeak resolution of 8.7% FWHM at -150/sup 0/C, using a pulse peaking time of 10 ..mu..s. When two 3 mm x 3 mm x 15 mm BGO crystals are coupled individually to SPDs and also coupled to a common 14 mm diam PMT, the SPDs detect the 511 keV photopeak with a resolution of 30% FWHM at -76/sup 0/C. In coincidence with an opposing 3 mm wide BGO crystal, the SPDs are able to identify the crystal of interaction with good signal-to-noise ratio, and the detector pair resolution is 2 mm FWHM. 32 references, 7 figures, 3 tables.

Derenzo, S.E.

1983-11-01

88

Analysis of Safflower Yellow in Food by Liquid Chromatography with Photodiode Array and Electrospray Mass Spectrometric Detection  

Microsoft Academic Search

The aim of the present study was to examine the applicability of liquid chromatography (LC) with photodiode array detection (PAD) and mass spectrometry (MS) for the determination of natural food colorants such as safflower yellow in foods. The main coloring constituents in safflower yellow as investigated by LC\\/PAD, were safflomin A (SF?A) and safflomin B (SF?B). The development of an

Koichi Inoue; Yuko Yamashita; Yoshihiro Yoshimura; Makiko Yamada; Mikio Nakamura; Yoshio Ito; Hiroyuki Nakazawa

2003-01-01

89

Modular radiation detector array and module  

SciTech Connect

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

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

1982-07-06

90

Single-Photon-Sensitive HgCdTe Avalanche Photodiode Detector  

NASA Technical Reports Server (NTRS)

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.

Huntington, Andrew

2013-01-01

91

Classification performance of carbon black-polymer composite vapor detector arrays as a function of array size and detector composition  

Microsoft Academic Search

The vapor classification performance of arrays of conducting polymer composite vapor detectors has been evaluated as a function of the number and type of detectors in an array. Quantitative performance comparisons were facilitated by challenging a collection of detector arrays with vapor discrimination tasks that were sufficiently difficult that at least some of the arrays did not exhibit perfect classification

Michael C Burl; Brian C Sisk; Thomas P Vaid; Nathan S Lewis

2002-01-01

92

Simultaneous determination of 12 chemical constituents in the traditional Chinese Medicinal Prescription Xiao-Yao-San-Jia-Wei by HPLC coupled with photodiode array detection.  

PubMed

An HPLC-photodiode array (PDA) detection method was established for the simultaneous determination of 12 components in Xiao-Yao-San-Jia-Wei (XYSJW): geniposide, puerarin, paeoniflorin, ferulic acid, liquiritin, hesperidin, naringin, paeonol, daidzein, glycyrrhizic acid, honokiol, and magnolol. These were separated in less than 70 min using a Waters Symmetry Shield RP 18 column with gradient elution using (A) acetonitrile, (B) water, and (C) acetic acid at a flow rate of 1 ml/min, and with a PDA detector. All calibration curves showed good linear regression (r(2)>0.9992) within the test ranges. The method was validated for specificity, accuracy, precision, and limits of detection. The proposed method enables in a single run the simultaneous identification and determination for quality control of 12 multi-structural components of XYSJW forming the basis of its therapeutic effect. PMID:18977108

Zhang, Hongmin; Chen, Shiwei; Qin, Feng; Huang, Xi; Ren, Ping; Gu, Xinqi

2008-12-15

93

Terahertz detectors and focal plane arrays  

NASA Astrophysics Data System (ADS)

Terahertz (THz) technology is one of emerging technologies that will change our life. A lot of attractive applications in security, medicine, biology, astronomy, and non-destructive materials testing have been demonstrated already. However, the realization of 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. As a result, THz radiation is resistant to the techniques commonly employed in these well established neighbouring bands. In the paper, issues associated with the development and exploitation of THz radiation detectors and focal plane arrays are discussed. Historical impressive progress in THz detector sensitivity in a period of more than half century is analyzed. More attention is put on the basic physical phenomena and the recent progress in both direct and heterodyne detectors. After short description of general classification of THz detectors, more details concern Schottky barrier diodes, pair braking detectors, hot electron mixers and field-effect transistor detectors, where links between THz devices and modern technologies such as micromachining are underlined. Also, the operational conditions of THz detectors and their upper performance limits are reviewed. Finally, recent advances in novel nanoelectronic materials and technologies are described. It is expected that applications of nanoscale materials and devices will open the door for further performance improvement in THz detectors.

Rogalski, A.; Sizov, F.

2011-09-01

94

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

NASA Astrophysics Data System (ADS)

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

Baptista, Brian

95

EUV detectors based on AlGaN-on-Si Schottky photodiodes  

NASA Astrophysics Data System (ADS)

Photodetectors designed for the Extreme Ultraviolet (EUV) range with the Aluminum Gallium Nitride (AlGaN) active layer are reported. AlGaN layers were grown by Molecular Beam Epitaxy (MBE) on Si(111) wafers. Different device structures were designed and fabricated, including single pixel detectors and 2D detector arrays. Sensitivity in different configurations was demonstrated, including front- and backside illumination. The latter was possible after integration of the detector chips with dedicated Si-based readouts using high-density In bump arrays and flip-chip bonding. In order to avoid radiation absorption in silicon, the substrate was removed, leaving a submicron-thin membrane of AlGaN active layer suspended on top of an array of In bumps. Optoelectrical characterization was performed using different UV light sources, also in the synchrotron beamlines providing radiation down to the EUV range. The measured cut-off wavelength of the active layer used was 280 nm, with a rejection ratio of the visible radiation above 3 orders of magnitude. Spectral responsivity and quantum efficiency values

Malinowski, P. E.; Duboz, J.-Y.; De Moor, P.; Minoglou, K.; John, J.; Srivastava, P.; Semond, F.; Frayssinet, E.; BenMoussa, A.; Giordanengo, B.; Van Hoof, C.; Mertens, R.

2011-05-01

96

Large Area Avalanche Photodiode Detectors for a Small Etendue Thomson Scattering Diagnostic  

NASA Astrophysics Data System (ADS)

The RFP requires a close conducting shell and small field errors. For this reason diagnostic ports are kept small, leading to a small etendue (0.19 mm^2-str) for TS light collection optics. In addition, the MST RFP operates at a low plasma density of ~ 10^13cm-3. Thomson scattered light levels are therefore lower than those found typically in tokamaks. Recently the MST TS system was upgraded to overcome the low signal level associated with its operational environment and to produce accurate single shot temperature measurements. Signal to noise enhancement was accomplished primarily through the use of 11 large area avalanche photodiode detectors with high quantum efficiency (90%) and low noise. Spectral coverage was increased from 50 nm to 100 nm. Single channel signal to noise improvement of 5X is expected, reducing the uncertainty in the electron temperature measurements from ~ 40% to ~ 10%. Preliminary results are reported. This work was supported by the U.S. D.O.E.

Biewer, T. M.; Stoneking, M. R.; den Hartog, D. J.

1996-11-01

97

Development of the ORRUBA Silicon Detector Array  

SciTech Connect

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.

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

98

SQUID Multiplexers for Cryogenic Detector Arrays  

NASA Technical Reports Server (NTRS)

SQUID multiplexers make it possible to build arrays of thousands of cryogenic detectors with a manageable number of readout channels. We are developing time-division SQUID multiplexers based on Nb trilayer SQUIDs to read arrays of superconducting transition-edge sensors. Our first-generation, 8-channel SQUID multiplexer was used in FIBRE, a one-dimensional TES array for submillimeter astronomy. Our second-generation 32-pixel multiplexer, based on an improved architecture, has been developed for instruments including Constellation-X, SCUBA-2, and solar x-ray astronomy missions. SCUBA-2, which is being developed for the James Clerk Maxwell Telescope, will have more than 10,000 pixels. We are now developing a third-generation architecture based on superconducting hot-electron switches. The use of SQUID multiplexers in instruments operating at above 2 K will also be discussed.

Irwin, Kent; Beall, James; Deiker, Steve; Doriese, Randy; Duncan, William; Hilton, Gene; Moseley, S. Harvey; Reintsema, Carl; Stahle, Caroline; Ullom, Joel; Vale, Leila

2004-01-01

99

Multiband selection with linear array detectors  

NASA Technical Reports Server (NTRS)

Several techniques that can be used in an earth-imaging system to separate the linear image formed after the collecting optics into the desired spectral band are examined. The advantages and disadvantages of the Multispectral Linear Array (MLA) multiple optics, the MLA adjacent arrays, the imaging spectrometer, and the MLA beam splitter are discussed. The beam-splitter design approach utilizes, in addition to relatively broad spectral region separation, a movable Multiband Selection Device (MSD), placed between the exit ports of the beam splitter and a linear array detector, permitting many bands to be selected. The successful development and test of the MSD is described. The device demonstrated the capacity to provide a wide field of view, visible-to-near IR/short-wave IR and thermal IR capability, and a multiplicity of spectral bands and polarization measuring means, as well as a reasonable size and weight at minimal cost and risk compared to a spectrometer design approach.

Richard, H. L.; Barnes, W. L.

1985-01-01

100

Adaptive Detector Arrays for Optical Communications Receivers  

NASA Technical Reports Server (NTRS)

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.

Vilnrotter, V.; Srinivasan, M.

2000-01-01

101

Identification and quantitation of iodotyrosines and iodothyronines in proteins using high-performance liquid chromatography by photodiode-array ultraviolet-visible detection.  

PubMed

We describe a new method for the separation, identification and quantitation of iodotyrosines and iodothyronines [3-monoiodo-L-tyrosine (MIT), 3,5-diiodo-L-tyrosine (DIT), L-thyronine (T0), 3,5-diiodo-L-thyronine (T2), 3,5,3'-triiodo-L-thyronine (T3), reverse 3,3',5'-triiodo-L-thyronine (rT3) and 3,3',5,5'-tetraiodo-L-thyronine (T4)]. Reversed-phase high-performance liquid chromatography (RP-HPLC) was performed on a Nucleosil C8 column with photodiode-array UV-Vis detection. A clearly defined elution profile was obtained of each iodoamino acid (iodotyrosines and iodothyronines) using a linear gradient from 20 to 80% phase B (90% acetonitrile, 10% water, 0.1% TFA), phase A (water, 0.1% TFA, pH 2.0) eluted over 40 min. Iodoamino acid composition was determined, taking into account retention times and spectral characteristics. Thyroid protein samples were digested enzymatically and the complex mixture of IAA was then injected onto the RP-HPLC system. A photodiode-array detector with a dynamic range in the UV-Vis region was used in the HPLC system to monitor the absorbance at different wavelengths continuously, collecting data which were compared with standard samples. Each IAA was quantitated using linear calibration curves obtained at 280 nm. This method allowed identification and quantitation of iodoamino acids from diverse sources in the range 2-500 ng, avoiding the need to radiolabel samples. The technique was tested with in vitro iodinated and non-iodinated human thyroglobulin and the recoveries ranged from 84 to 91%. PMID:9029324

de la Vieja, A; Calero, M; Santisteban, P; Lamas, L

1997-01-10

102

Design of a back-illuminated, crystallographically etched, silicon-on-sapphire avalanche photodiode with monolithically integrated microlens, for dual-mode passive & active imaging arrays  

NASA Astrophysics Data System (ADS)

There is a growing need in space and environmental research applications for dual-mode, passive and active 2D and 3D ladar imaging methods. To fill this need, an advanced back-illuminated avalanche photodiode (APD) design is presented based on crystallographically etched (100) epitaxial silicon on R-plane sapphire (SOS), enabling single photon sensitive, solid-state focal plane arrays (FPAs) with wide dynamic range, supporting passive and active imaging capability in a single FPA. When (100) silicon is properly etched with KOH:IPA:H2O solution through a thermally grown oxide mask, square based pyramidal frustum or mesa arrays result with the four mesa sidewalls of the APD formed by (111) silicon planes that intersect the (100) planes at a crystallographic angle, ?c = 54.7°. The APD device is fabricated in the mesa using conventional silicon processing technology. Detectors are back-illuminated through light focusing microlenses fabricated in the thinned, AR-coated sapphire substrate. The APDs share a common, front-side anode contact, made locally at the base of each device mesa. A low resistance (Al) or (Cu) metal anode grid fills the space between pixels and also inhibits optical cross-talk. SOS-APD arrays are indium bump-bonded to CMOS readout ICs to produce hybrid FPAs. The quantum efficiency for the square 27 µm pixels exceeds 50% for 250 nm < ? < 400 nm and exceeds 80% for 400 nm < ? < 700 nm. The sapphire microlenses compensate detector quantum efficiency loss resulting from the mesa geometry and yield 100% sensitive-area-fill-factor arrays, limited in size only by the wafer diameter.

Stern, Alvin G.; Cole, Daniel C.

2008-12-01

103

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

E-print Network

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.

Feng, H; Feng, Hua; Kaaret, Philip

2006-01-01

104

InP-based Geiger-mode avalanche photodiode arrays for three-dimensional imaging at 1.06 ?m  

NASA Astrophysics Data System (ADS)

We report on the development of 32 x 32 focal plane arrays (FPAs) based on InGaAsP/InP Geiger-mode avalanche photodiodes (GmAPDs) designed for use in three-dimensional (3-D) laser radar imaging systems at 1064 nm. To our knowledge, this is the first realization of FPAs for 3-D imaging that employ a planar-passivated buried-junction InP-based GmAPD device platform. This development also included the design and fabrication of custom readout integrate circuits (ROICs) to perform avalanche detection and time-of-flight measurements on a per-pixel basis. We demonstrate photodiode arrays (PDAs) with a very narrow breakdown voltage distribution width of 0.34 V, corresponding to a breakdown voltage total variation of less than +/- 0.2%. At an excess bias voltage of 3.3 V, which provides 40% pixel-level single photon detection efficiency, we achieve average dark count rates of 2 kHz at an operating temperature of 248 K. We present the characterization of optical crosstalk induced by hot carrier luminescence during avalanche events, where we show that the worst-case crosstalk probability per pixel, which occurs for nearest neighbors, has a value of less than 1.6% and exhibits anisotropy due to isolation trench etch geometry. To demonstrate the FPA response to optical density variations, we show a simple image of a broadened optical beam.

Itzler, Mark A.; Entwistle, Mark; Owens, Mark; Jiang, Xudong; Patel, Ketan; Slomkowski, Krystyna; Koch, Tim; Rangwala, Sabbir; Zalud, Peter F.; Yu, Young; Tower, John; Ferraro, Joseph

2009-05-01

105

Development of high-transmittance back-illuminated silicon-on-sapphire substrates thinned below 25 micrometers and bonded to fused silica for high quantum efficiency and high resolution avalanche photodiode imaging arrays  

NASA Astrophysics Data System (ADS)

There is a growing need in 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. To support the fabrication of large scale, high quantum efficiency and high resolution silicon avalanche photodiode arrays and other advanced solid-state optoelectronics, a novel, high transmittance, backilluminated silicon-on-sapphire substrate has been developed incorporating a single crystal, epitaxially grown aluminum nitride (AlN) antireflective layer between silicon and R-plane sapphire, that provides refractive index matching to improve the optical transmittance into silicon from sapphire. A one quarter wavelength magnesium fluoride antireflective layer deposited on the back-side of the sapphire improves optical transmittance from the ambient into the sapphire. The magnesium fluoride plane of the Si-(AlN)-sapphire substrate is bonded to a fused silica wafer that provides mechanical support, allowing the sapphire to be thinned below 25 micrometers to improve back-illuminated optical transmittance, while suppressing indirect optical crosstalk from APD emitted light undergoing reflections in the sapphire, to enable high quantum efficiency and high resolution detector arrays.

Stern, Alvin G.

2012-03-01

106

Microphone array based novel infant deafness detector.  

PubMed

This work focuses on an infant deafness detector unit, using the concept of microphone array. This instrument is based on the principle of evoked acoustic emissions (OAEs). The key feature of the microphone array is its ability to increase signal-to-noise ratio (SNR) and reproducibility of the OAE responses. These further significantly contribute to improve the sensitivity and specificity of the overall system. Low level sound pressure values are recorded by the sensitive microphones in microphone array unit and processed using TI's DSP6416. The sound stimulus transmitted to human ear is generated and controlled by the 6416 DSP (Digital signal processor). Hardware circuit details and the algorithm used in signal processing are discussed in this paper. Standard averaging technique is used in the implemented algorithm. The final result speaks about the hearing capacity of a patient. The proof that the usage of microphone arrays leads to better SNR values than using a single microphone in an OAE probe, is successfully carried out in this work. PMID:21097204

Agnihotri, Chinmayee; Thiyagarajan, S; Kalyansundar, Archana

2010-01-01

107

Astronomical imaging with infrared array detectors.  

PubMed

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

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

1988-12-01

108

Impact of a New Highly Sensitive HgCdTe Avalanche Photodiode Detector on Receiver Performance for the CO2 Sounder Lidar for the ASCENDS Mission  

NASA Astrophysics Data System (ADS)

NASA Goddard Space Flight Center (GSFC) is currently developing a CO2 lidar as a candidate for the NASA's planned ASCENDS mission under the support of Earth Science Technology Office (ESTO) Instrument Incubator Program (IIP). As part of this work we have demonstrated new type of lower noise HgCdTe avalanche photodiode (APD) multi-element detector for the lidar receiver. This significantly improves the receiver sensitivity, lower the laser power, and reduce the receiver telescope size compared to InGaAs photomultiplier tubes (PMT) and APDs currently used. The HgCdTe APD arrays were designed and manufactured by DRS Technologies, Reconnaissance, Surveillance and Target Acquisition (RSTA) Division, which combines their mature HgCdTe APD detector in a hybrid package with a new custom cryogenic silicon preamplifier. The new detectors were specially designed for our airborne CO2 lidar and operate at ~ 77K inside a turn-key closed-cycle cooler. The detector has 80 ?m square pixels in a 4x4 array, and >70% fill factor and was custom designed to match the optics of our airborne and eventually space-based CO2 lidar. The initial results of evaluating the detector at NASA GSFC showed the HgCdTe APD assembly has a quantum efficiency of ~90% near 1550-nm, >500 APD gain, 8-10 MHz electrical bandwidth, and an average noise equivalent power of <1fW/Hz1/2. The detector also has a much wider linear dynamic range than PMTs, since it operates in a linear analog mode and has variable gain. Given the wide range of surface reflectivities this is important for ASCENDS. The new detector also greatly improves our CO2 lidar's receiver sensitivity. Calculations show it enables us to reduce the laser transmitter power by half for the space borne instrument while staying with a conventional reasonably sized (~1.2 m) diameter receiver telescope. We will show analysis and laboratory test results of the CO2 lidar performance using a receiver with this new detector. We are also funded by NASA ESTO to develop a high bandwidth HgCdTe APD under an Advanced Component Technology (ACT) program. DRS RSTA will use a new higher speed preamplifier and reduce the input capacitance to further reduce the noise and achieve linear mode photon counting performance.

Sun, X.; Abshire, J. B.

2013-12-01

109

Digital radiography: Present detectors and future developments  

SciTech Connect

Present detectors for digital radiography are of two classes: real time detectors and storage (non real time) types. Present real time detectors consist of image intensifier tubes with an internal cesium iodide layer x-ray converter. Non real time detectors involve linear sweep arrays or storage detectors such as film. Future detectors discussed here can be of both types utilizing new technologies such as hydrogenated amorphous silicon photodiode arrays coupled to thin film transistor arrays. 17 refs., 10 figs.

Perez-Mendez, V.

1990-08-01

110

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...

111

Simultaneous analysis of anthocyanins and flavonols in petals of lotus ( Nelumbo) cultivars by high-performance liquid chromatography-photodiode array detection\\/electrospray ionization mass spectrometry  

Microsoft Academic Search

A fast and reliable HPLC method for the simultaneous separation of anthocyanins and flavonols in lotus petals was developed based on the study of four candidate solvent systems. Fifteen flavonoids were identified by high-performance liquid chromatography with photodiode array detection\\/mass spectrometry. Among them, two anthocyanins and nine flavonols were discovered in lotus petals for the first time. This work is

Rui-Zhen Yang; Xiao-Lei Wei; Fen-Fang Gao; Liang-Sheng Wang; Hui-Jin Zhang; Yan-Jun Xu; Chong-Hui Li; Yu-Xuan Ge; Jing-Jing Zhang; Jie Zhang

2009-01-01

112

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

Microsoft Academic Search

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

Berthold Büchele; Thomas Simmet

2003-01-01

113

CORSIKA Simulation of the Telescope Array Surface Detector  

E-print Network

The Telescope Array is the largest experiment studying ultra-high energy cosmic rays in the northern hemisphere. The detection area of the experiment consists of an array of 507 surface detectors, and a fluorescence detector divided into three sites at the periphery. The viewing directions of the 38 fluorescence telescopes point over the air space above the surface array. In this paper, we describe a technique that we have developed for simulating the response of the array of surface detectors of the Telescope Array experiment. The two primary components of this method are (a) the generation of a detailed CORSIKA Monte Carlo simulation with all known characteristics of the data, and (b) the validation of the simulation by a direct comparison with the Telescope Array surface detector data. This technique allows us to make a very accurate calculation of the acceptance of the array. We also describe a study of systematic uncertainties in this acceptance calculation.

,

2014-01-01

114

Indium antimonide large-format detector arrays  

NASA Astrophysics Data System (ADS)

Large format infrared imaging sensors are required to achieve simultaneously high resolution and wide field of view image data. Infrared sensors are generally required to be cooled from room temperature to cryogenic temperatures in less than 10 min thousands of times during their lifetime. The challenge is to remove mechanical stress, which is due to different materials with different coefficients of expansion, over a very wide temperature range and at the same time, provide a high sensitivity and high resolution image data. These challenges are met by developing a hybrid where the indium antimonide detector elements (pixels) are unconnected islands that essentially float on a silicon substrate and form a near perfect match to the silicon read-out circuit. Since the pixels are unconnected and isolated from each other, the array is reticulated. This paper shows that the front side illuminated and reticulated element indium antimonide focal plane developed at L-3 Cincinnati Electronics are robust, approach background limited sensitivity limit, and provide the resolution expected of the reticulated pixel array.

Davis, Mike; Greiner, Mark

2011-06-01

115

Multiwavelength infrared focal plane array detector  

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

116

The Impact of Array Detectors on Raman Spectroscopy  

ERIC Educational Resources Information Center

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.

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

2007-01-01

117

Fabrication of Pop-up Detector Arrays on Si Wafers  

NASA Technical Reports Server (NTRS)

High sensitivity is a basic requirement for a new generation of thermal detectors. To meet the requirement, close-packed, two-dimensional silicon detector arrays have been developed in NASA Goddard Space Flight Center. The goal of the task is to fabricate detector arrays configured with thermal detectors such as infrared bolometers and x-ray calorimeters to use in space fliGht missions. This paper focuses on the fabrication and the mechanical testing of detector arrays in a 0.2 mm pixel size, the smallest pop-up detectors being developed so far. These array structures, nicknamed "PUDS" for "Pop-Up Detectors", are fabricated on I pm thick, single-crystal, silicon membranes. Their designs have been refined so we can utilize the flexibility of thin silicon films by actually folding the silicon membranes to 90 degrees in order to obtain close-packed two-dimensional arrays. The PUD elements consist of a detector platform and two legs for mechanical support while also serving as electrical and thermal paths. Torsion bars and cantilevers connecting the detector platform to the legs provide additional flexures for strain relief. Using micro-electromechanical structure (MEMS) fabrication techniques, including photolithography, anisotropic chemical etching, reactive-ion etching, and laser dicing, we have fabricated PLTD detector arrays of fourteen designs with a variation of four parameters including cantilever length, torsion bar length and width, and leg length. Folding tests were conducted to test mechanical stress distribution for the array structures. We obtained folding yields and selected optimum design parameters to reach minimal stress levels. Computer simulation was also employed to verify mechanical behaviors of PUDs in the folding process. In addition, scanning electron microscopy was utilized to examine the flatness of detectors and the alignment of detector pixels in arrays. The fabrication of thermistors and heaters on the pop-up detectors is under way, preparing us for the next step of the experiment, the thermal test.

Li, Mary J.; Allen, Christine A.; Gordon, Scott A.; Kuhn, Jonathan L.; Mott, David B.; Stahle, Caroline K.; Wang, Liqin L.

1999-01-01

118

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

NASA Astrophysics Data System (ADS)

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.

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

1992-08-01

119

Differential optical proximity detector  

NASA Technical Reports Server (NTRS)

Updated detector can operate under ambient light and uses multiple detectors to locate objects in several different spacial volumes. Sensitivity is approved by scanning field-of-view twice: once with coherent light source turned on and once with background light only. Detector outputs for two cases are amplified and subtracted for each photodiode sensor in array, to eliminate effect of background light.

Johnston, A. R.; Shimada, K.; Tippins, H. H., Jr.

1977-01-01

120

Quantification of fumaric acid in liver, spleen and urine by high-performance liquid chromatography coupled to photodiode-array detection.  

PubMed

Quantification of fumaric acid, an endogenous dicarboxylic acid with interesting biomedical applications either through its own biological activity or as a linker constitutive of the porous iron(III) fumarate metal organic framework (MOF) MIL-88A based drug nanocarrier (MIL stands for Material from Institut Lavoisier), has been developed in different rat biological complex media (liver, spleen and urine). After a liquid-liquid extraction procedure, fumaric acid concentration was determined by a simple and accurate high-performance liquid chromatography (HPLC) method coupled to a photodiode-array detector (PDA) using aminosalicylic acid as internal standard (IS) and a gradient elution. The recovery of fumaric acid reaches 89% and 92% for urine (for concentrations of 0.05 and 1?gml(-1), respectively) and 90% for liver and spleen tissues, exceeding 89% in all instances in comparison with the IS. Linearity has been kept from 0.05 to 1?gml(-1) and from 0.5 to 10?gg(-1) of fumaric acid in urine and tissues, respectively. The limit of detection of the method was 0.01?g per injection. This method has finally allowed the quantification of fumaric acid in rat urine and tissue samples after the intravenous administration of MIL-88A nanoparticles. PMID:21820831

Baati, Tarek; Horcajada, Patricia; Gref, Ruxandra; Couvreur, Patrick; Serre, Christian

2011-12-01

121

Detector array for measuring far-field energy density distribution of repetitively pulsed laser  

NASA Astrophysics Data System (ADS)

A system based on detector array is developed to measure the far-field temporal and spatial distribution and absolute pulse energy density of the laser beam. In this experiment, the duration of the laser pulse is about 15ns, the repetition rate is 400Hz, and the diameter of the far-field beam is about 60cm. The detector array is composed of 112 Si-PIN photodiode detectors and arranged to be a disk with spatial sample rate of 0.4cm -1. Charge sensitive amplifiers and baseline restoration circuits are used to collect photocurrent of the detectors, and current-input AD converters with integrator front-end are used to digitalize the multi channel signals. The far-field laser beam profile is reconstructed with the spatial sample data using special arithmetic of spatial interpolation. The system is capable for absolutely measuring far-field energy density distribution of repetitively pulsed laser, with response wavelength between 400nm and 1100nm, minimal detectable pulse duration of about 10ns, and energy density of 0.1-100?J/cm2.

Yang, Pengling; Feng, Guobin; Wang, Qunshu; Wang, Jingjin; Cheng, Jianping

2008-03-01

122

Development of a Validated HPLC/Photodiode Array Method for the Determination of Isomenthone in the Aerial Parts of Ziziphora tenuior L.  

PubMed Central

Background Ziziphora tenuior L. known as Kakuti in Persian, is used in traditional medicine for fever, dysentery, uterus infection and as an analgesic. It is used also in the treatment of gastrointestinal disorders as carminative, or remedy of diarrhea or nausea. Major components of plant essential oil including pulegone, isomenthone, thymol, menthone, and piperitone are suggested to be responsible for the mentioned medicinal properties. Objectives In the present study, a normal high performance liquid chromatography (HPLC)/photodiode array validated method for quantification of isomenthone, one of the major constituents of Ziziphora, was established for the first time with a simple, rapid and accurate method. Materials and Methods HPLC analysis was done on a Waters system, equipped with 515 HPLC pump and waters 2996 photodiode array detector. The column was a Nova-Pak Silica (3.9 × 150 mm), and Empower software was used for the determination of the compounds and processing the data. The method was validated according to USP 32 requirements. Results A selective method for the resolution of isomenthone from two nearest peaks, thymol, and carvacrol was obtained with gradient system of hexane (A), and hexane: ethyl acetate (9:1) (B), starting with A: B (100:0) for 2 minutes, then 0?20% B in 5 minutes, A:B (80:20) for 5 minutes, then 20-30% B in 3 minutes, 30-100% B for 5 minutes, A:B (0:100) for 4 minutes following with equilibrating for 10 minutes. The flow rate was 1 mL/min at 22?C and the injection volume for the standards and the samples was 20 ?L. The retention time for isomenthone was found to be 7.45 minutes. The regression equation was y = 143235x - 2433 with the correlation co-factor R2 = 0.9992 and the percent recovery of 65.4 ± 3.85%. The sample obtained from 5 g of Z. teniour dried powder in 6 mL extract was standardized to contain 1.14 ± 0.030 ?L/mL isomenthone which is equivalent to % 1.37 ?L/g of the dried powdered plant. Limit of detection (LOD) and Limit of Quantification (LOQ) were 0.037, and 0.122 µL/mL determined by using the formula based on the signal to noise ratio. Conclusions Due to this fact that plant extracts may cause irreversible damages to the capillary GC columns, using validated HPLC method for the analysis of these compounds in cruse plant extracts is recommended. PMID:24624211

Ghassemi, Nasrollah; Ghanadian, Mustafa; Ghaemmaghami, Lili; Kiani, Haran

2013-01-01

123

Spada: An Array of Spad Detectors For Astrophysical Applications  

Microsoft Academic Search

Astrophysical studies require accurate, sensitive and fast detectors to detect faint sources with high variability. Recently an array of Single Photon Avalanche Diodes (SPAD), SPADA, has been developed. This array is suitable for competitive adaptive optics operations and fast transient image acquisition at a fraction of the current cost of imaging arrays. The fabricated solid-state photon counters are rugged, easily

Giovanni Bonanno; Massimiliano Belluso; Franco Zappa; Simone Tisa; Sergio Cova; Piera Maccagnani; Domenico Bonaccini Calia; Roberto Saletti; Roberto Roncella; Sergio Billotta

2005-01-01

124

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

NASA Astrophysics Data System (ADS)

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 “pig”. 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 “pulse-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.

Carroll, Lewis

2014-02-01

125

Deployment of the SNO Neutral Current Detector Array  

NASA Astrophysics Data System (ADS)

An array of low background neutron detectors has recently been installed in the heavy water region of the SNO detector. The neutral current detector (NCD) array consists of 36 proportional counters filled with ^3He-CF4 gas and 4 proportional counters filled with ^4He-CF_4. These detectors were deployed using specially designed hardware that conforms to the high radiopurity requirements in SNO. NCD segments are laser welded in place directly over the access point to the heavy water of the SNO detector and lowered into the detector volume using a hauldown mechanism. A one-of-a-kind remotely operated vehicle (ROV) is employed to remove the NCD string from the hauldown system and install it in the designated location within the detector. Many aspects of the array deployment process will be presented.

Heise, Jaret

2004-05-01

126

The NSLS 100 element solid state array detector  

Microsoft Academic Search

X-ray absorption studies of dilute samples require fluorescence detection techniques. Since signal-to-noise ratios are governed by the ratio of fluorescent to scattered photons counted by a detector, solid state detectors which can discriminate between fluorescence and scattered photons have become the instruments of choice for trace element measurements. Commercially available 13 element Ge array detectors permitting total count rates <

L. R. Furenlid; H. W. Kraner; L. C. Rogers; S. P. Cramer; D. Stephani; R. H. Beuttenmuller; J. Beren

1992-01-01

127

Design and testing of an active quenching circuit for an avalanche photodiode photon detector  

NASA Technical Reports Server (NTRS)

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.

Arbel, D.; Schwartz, J. A.

1991-01-01

128

Mirror telescope for long linear detector arrays  

NASA Astrophysics Data System (ADS)

Detector developments raise the possibility of achieving high resolution images, employing linear arrays of over 3000 pixels, in any of the atmospheric windows extending from the visual to the far infra-red. Simultaneous capture with fusion of the VNIR, MWIR & LWIR images requires a reflective optical system. Reasons are given for the choice of a 4 mirror anastigmatic telescope for the basic imaging system which is combined with another 4 mirror afocal telescope to cover a 60 degree field in wide angle mode. To permit ground based trials, a mirror scanner covers a 40 degree field in either mode. Choice of a telescope with projected entrance pupil was essential for a compact system. Focus and mode changes are all made by the movement of flat mirrors. A particular arrangement of these folds contributes towards a rational structure with the mirror groups mounted on optical axes perpendicular to a common base. The methods used to ensure dimensional stability including the design and mounting of the beamsplitters are described.

Lidwell, Michael O.

1998-10-01

129

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

PubMed

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. PMID:25006986

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

2014-07-01

130

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

131

Development of 58 x 62 Si:Sb detector arrays  

NASA Technical Reports Server (NTRS)

The fabrication of antimony doped silicon (Si:Sb) detector arrays are described for use in 30 micron infrared imaging applications. The operation of the multiplexer readout circuit which will be used for this application is also described.

Worley, S.; Gaalema, S.

1986-01-01

132

PbS-PbSe IR detector arrays  

NASA Technical Reports Server (NTRS)

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.

Barrett, John R. (Inventor)

1986-01-01

133

Superconducting-nanowire single-photon-detector linear array  

E-print Network

We designed, fabricated, and tested a one-dimensional array of superconducting-nanowire single-photon detectors, integrated with on-chip inductors and resistors. The architecture is suitable for monolithic integration on ...

Zhao, Qingyuan

134

High-performance liquid chromatography with photodiode array detection for determination of nobiletin content in the brain and serum of mice administrated the natural compound  

Microsoft Academic Search

We recently demonstrated that nobiletin, a citrus flavonoid, exhibits anti-dementia action in animals. However, no determination\\u000a methods for the content of nobiletin with beneficial action in the brain of nobiletin-administered animals have been developed,\\u000a nor has its pharmacokinetics been revealed completely. Here, we established the high-performance liquid chromatography\\/photodiode\\u000a array detection method for nobiletin determination using Bond Elut C18 SPE cartridges

Daisuke Saigusa; Masatoshi Shibuya; Daisuke Jinno; Hiroyuki Yamakoshi; Yoshiharu Iwabuchi; Akihito Yokosuka; Yoshihiro Mimaki; Akira Naganuma; Yasushi Ohizumi; Yoshihisa Tomioka; Tohru Yamakuni

135

Analysis of tetrabromobisphenol A and other phenolic compounds in water samples by non-aqueous capillary electrophoresis coupled to photodiode array ultraviolet detection  

Microsoft Academic Search

Non-aqueous capillary electrophoresis (NACE) with large-volume sample stacking injection using the electroosmotic flow pump (LVSEP) has been developed for the determination of tetrabromobisphenol A (TBBPA) and other phenolic compounds in environmental matrices. Methanol has been used as run buffer solvent to reduce the electroosmotic flow (EOF). Identification and quantification of the analytes was performed by photodiode array ultraviolet detection. LVSEP–NACE

E. Blanco; M. C. Casais; M. C. Mejuto; R. Cela

2005-01-01

136

Use of high-performance liquid chromatography with photodiode-array UV detection for the creation of a 600-compound library application to forensic toxicology  

Microsoft Academic Search

A high-performance liquid chromatographic method is described with photodiode array detection for systematic toxicological analysis in human blood and urine. After a single step liquid-liquid extraction using Toxi-Tube A, drugs are analyzed with a multi step gradient (phosphate pH 3.8-acetonitrile) on a Symmetry C8 5-?m column (250 mm × 4.6 mm I.D.) (Waters), operated at 30°C. The flow-rate is varied

Yvan Gaillard; Gilbert Pépin

1997-01-01

137

Determination of 40 synthetic food colors in drinks and candies by high-performance liquid chromatography using a short column with photodiode array detection  

Microsoft Academic Search

Forty synthetic food colors were determined in drinks and candies by reversed-phase high-performance liquid chromatography with photodiode array detection. The following food colors were analyzed within 19min using a short analytical column (50mm×4.6mm i.d., 1.8?m) at 50°C with gradient elution: Ponceau 6R, Tartrazine, Fast yellow AB, Amaranth, Indigotine, Naphthol yellow S, Chrysoine, Ponceau 4R, Sunset yellow FCF, Red 10B, Orange

N. Yoshioka; K. Ichihashi

2008-01-01

138

Determination of saffron ( Crocus sativus L.) components in crude plant extract using high-performance liquid chromatography-UV-visible photodiode-array detection-mass spectrometry  

Microsoft Academic Search

The determination of saffron components in crude plant extracts by high-performance liquid chromatography -UV-visible photodiode-array detection on-line with mass spectrometry is described. The method is shown to be suitable for the determination of picrocrocin, the glycosidic precursor of safranal, safranal and flavonoids; it is the technique of choice for the analysis of crocetin glycosides (crocins) carrying one up to five

Petros A. Tarantilis; George Tsoupras; Moschos Polissiou

1995-01-01

139

Particle Identification in the NIMROD-ISiS Detector Array  

SciTech Connect

Interest in the influence of the neutron-to-proton (N/Z) ratio on multifragmenting nuclei has demanded an improvement in the capabilities of multi-detector arrays as well as the companion analysis methods. The particle identification method used in the NIMROD-ISiS 4{pi} array is described. Performance of the detectors and the analysis method are presented for the reaction of {sup 86}Kr+{sup 64}Ni at 35 MeV/u.

Wuenschel, S.; Hagel, K.; May, L. W.; Wada, R.; Yennello, S. J. [Texas A and M University Cyclotron Institute College Station TX 77843 (United States)

2009-03-10

140

Particle Identification in the NIMROD-ISiS Detector Array  

E-print Network

Interest in the influence of the neutron-to-proton (N/Z) ratio on multifragmenting nuclei has demanded an improvement in the capabilities of multi-detector arrays as well as the companion analysis methods. The particle identification method used in the NIMROD-ISiS 4 $\\pi$ array is described. Performance of the detectors and the analysis method are presented for the reaction of 86Kr+64Ni at 35MeV/u.

S. Wuenschel; K. Hagel; L. W. May; R. Wada; S. J. Yennello

2009-03-04

141

Large area germanium detector arrays for lung counting: what is the optimum number of detectors?  

PubMed

Using the Lawrence Livermore National Laboratory (LLNL) torso phantom to calibrate a lung counting system can lead to the conclusion that three large area (i.e. >70 mm diameter) Ge detectors will outperform a four-detector array and provide a lower MDA as a four-detector array of large area Ge detectors covers a significant portion of inactive tissue (i.e. non-lung tissue). The lungs of the LLNL phantom, which are approximately 10 cm too short compared with real lungs, also suggests that a two-detector array could be used under limited circumstances. When tested with modified lungs that are more human-like, it was found that the four-detector array showed the best counting efficiency and the lowest MDA. Fortunately, these findings indicate that, although the LLNL phantom's lungs are too short, there is no adverse impact on the calibration of a lung counter. PMID:17151008

Kramer, Gary H; Hauck, Barry M

2007-01-01

142

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

Microsoft Academic Search

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

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

1999-01-01

143

Ultrasound-assisted extraction of phenolic compounds from strawberries prior to liquid chromatographic separation and photodiode array ultraviolet detection.  

PubMed

Ultrasound-assisted extraction was used for the determination of phenolic compounds present in strawberries. The optimization study of the extraction was carried out using spiked samples (100 mg/kg). The sample immersed in an aqueous solution containing hydrochloric acid (0.4 M) was sonicated for 2 min (duty cycle 0.2 s, output amplitude 20% of the nominal amplitude of the converter, applied power 100 W with the probe placed 1cm from the bottom of the water bath and 5 cm from the walls of the precipitate glass). Subsequent separation was carried out by liquid chromatography (LC) with photodiode array UV detection. Calibration curves using the standard addition in green strawberries typically gave linear dynamic ranges of 2-300 mg/l for all analytes; R(2) values exceeded 0.996 in all cases. The method was applied to two types of strawberries to demonstrate the applicability of the proposed method, which is much faster and produces less analyte degradation than methods as solid-liquid, subcritical water and microwave-assisted extraction. PMID:16203008

Herrera, M C; de Castro, M D Luque

2005-12-23

144

Feasibility study to determine correct focus by analyzing photon distributions on Geiger-mode avalanche photodiode focal plane array  

NASA Astrophysics Data System (ADS)

A method to determine correct focus in direct detection laser radar system using Geiger-mode avalanche photodiode focal plane array (GmAPD-FPA) is proposed. It is implemented by laser pulses with controlled beam diameter and energy on a distant target. And the time-of-flight (TOF) of laser pulses are obtained for each pixel in GmAPD-FPA. With multiple laser pulses, time correlated single photon counting (TCSPC) is carried out to obtain target detection probability. Using target detection probabilities of each pixel, the photon distribution on GmAPD-FPA is acquired. The condition to determine correct focus is the minimum photon distribution in GmAPD-FPA. In theory part, the range of laser pulse energy is decided. The experiments are carried out with commercial 1x8 pixel GmAPD-FPA. The experimental results show that the focus position is founded using this method and a spatial resolution of a laser radar system is improved where the 1x8 pixel GmAPD-FPA is located in focus position.

Kim, Tae Hoon; Kong, Hong Jin; Jo, Sung Eun; Oh, Min Seok

2011-06-01

145

Charge Transport in Arrays of Semiconductor Gamma-Ray Detectors  

Microsoft Academic Search

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

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

1995-01-01

146

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

PubMed Central

Abstract. 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

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

2013-01-01

147

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

NASA Astrophysics Data System (ADS)

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.

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

2014-01-01

148

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

PubMed

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

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

2014-01-01

149

Small HgCdTe infrared detector arrays from UWA  

Microsoft Academic Search

Single infrared detectors and small arrays find widespread applications in spectroscopy, radiometry, scanning imaging systems, target tracking etc. The technology of such devices based on mercury cadmium telluride (HgCdTe), the material of choice for high performance infrared detectors, has been a subject of intensive research in many countries. Projects conducted in this field at The University of Western Australia resulted

J. Antoszewski; C. A. Musca; J. M. Dell; L. Faraone; M. Wagener; I. Switala; R. Oermann

2002-01-01

150

64-Pixel linear-array Si-APD detector for X-ray time-resolved experiments  

NASA Astrophysics Data System (ADS)

We have developed a silicon avalanche-photodiode (Si-APD) linear array detector to be used for time-resolved measurements in pulsed synchrotron X-ray experiments. The Si-APD linear array consists of 64 pixels 100×200 ?m2, with a pixel pitch of 150 ?m and a depletion depth of 10 ?m. The nanosecond response and high counting rate of the Si-APD are very valuable for time-resolved X-ray diffraction experiments using pulsed synchrotron radiation. A detector system that can resolve successive X-ray pulses within a short interval of 2 ns would be very efficient for recording the intensity and position of X-ray diffraction patterns within a nanosecond period. A prototype detector system equipped with an ultrafast application-specific integrated circuit, field-programmable gate arrays and network processor boards was fabricated. It allowed a high count-rate of >107 cps per channel with a synchrotron X-ray beam; however, the time resolution was limited to 10 ns. The detector successfully recorded small-angle X-ray scattering by scanning the detector position.

Kishimoto, S.; Yonemura, H.; Adachi, S.; Shimazaki, S.; Ikeno, M.; Saito, M.; Taniguchi, T.; Tanaka, M.

2013-12-01

151

Towards large scale HTS Josephson detector arrays for THz imaging  

NASA Astrophysics Data System (ADS)

We present the design and implementation of a high-temperature superconducting (HTS) Josephson junction detector array for terahertz (THz) imaging. The array device is made of ten YBa2Cu3Ox-7 (YBCO) step-edge junctions coupled to gold thin-film ring-slot antennas on a MgO substrate. The design and characterization of the detector array in response to a 0.6 THz signal are presented. The development of multi-channel biasing and read-out electronics and the system integration with a commercial cryocooler are also described.

Du, J.; Hellicar, A. D.; Leslie, K. E.; Nikolic, N.; Hanham, S. M.; Macfarlane, J. C.; Foley, C. P.

2013-11-01

152

Analysis of alkaloids in Coptis chinensis Franch by accelerated solvent extraction combined with ultra performance liquid chromatographic analysis with photodiode array and tandem mass spectrometry detections.  

PubMed

A new method based on accelerated solvent extraction (ASE) followed by ultra performance liquid chromatography (UPLC) analysis has been developed for the identification and quantification of major alkaloids in extracts of Coptis chinensis Franch. The UPLC system consisted of a dual detection system of photodiode array detector (PDA) and positive ion electrospray ionization-tandem mass spectrometry (ESI-MS/MS) in sequential configuration. The operational parameters of ASE including extraction solvent, extraction temperature, static extraction time and extraction cycles were optimized. UPLC analysis was performed on an ACQUITY UPLC BEH C(18) column eluted by a mobile phase of acetonitrile spiked with a buffer solution consisting of 0.50% acetic acid and 20 mmol L(-1) ammonium acetate. A tandem quadrupole spectrometer operating in either full scan mode or in MS/MS mode for multiple reaction monitoring (MRM) was used for the identification and quantitative analysis of eight major alkaloids in C. chinensis Franch extracts. The samples were also analyzed on a high-performance liquid chromatography-electrospray ionization-time-of-flight mass spectrometry (HPLC-ESI-TOF-MS) system to confirm the identification results. Three of the eight major alkaloids, berberine, palmatine and jatrorrhizine were quantified by UPLC-PDA and UPLC-MS/MS. The results indicated that both UPLC-PDA and UPLC-MS/MS methods were simple, sensitive and reliable for the determination of alkaloids in C. chinensis Franch. Seven Huanglian samples from different locations were analyzed using the established methods. UPLC fingerprints based on the distribution of the eight major alkaloids can serve as a rapid and reliable method for the authentication and quality evaluation of traditional Chinese medicine (TCM) herbs. PMID:18395058

Chen, Junhui; Wang, Fengmei; Liu, Jie; Lee, Frank Sen-Chun; Wang, Xiaoru; Yang, Huanghao

2008-04-21

153

Beam profile monitor for the NSLS vuv ring employing linear photodiode arrays  

SciTech Connect

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 synchrotron radiation. We discuss a system which monitors the two-dimensional profile of the synchrotron light in the NSLS vuv ring using commercially available high-resolution linear photosensitive diode arrays. The optical system has been 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.

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

1985-01-01

154

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

PubMed Central

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

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

2012-01-01

155

Bolometeric detector arrays for CMB polarimetry  

NASA Technical Reports Server (NTRS)

We describe the development of antenna coupled bolometers for CMB polarization experiments. The necessary components of a bolometric CMB polarimeter - a beam forming element, a band defining filter, and detectors - are all fabricated on a silicon chip with photolithography.

Kuo, C. L.; Bock, J. J.; Day, P.; Goldin, A.; Golwala, S.; Holmes, W.; Irwin, K.; Kenyon, M.; Lange, A. E.; LeDuc, H. G.; Rossinot, P.; Sterb, J.; Vayonakis, A.; Wang, G.; Yun, M.; Zmuidzinas, J.

2005-01-01

156

Adaptive Waveform Correlation Detectors for Arrays: Algorithms for Autonomous Calibration  

SciTech Connect

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.

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

2009-07-23

157

Integrated Miniature Arrays of Optical Biomolecule Detectors  

NASA Technical Reports Server (NTRS)

Integrated miniature planar arrays of optical sensors for detecting specific biochemicals in extremely small quantities have been proposed. An array of this type would have an area of about 1 cm2. Each element of the array would include an optical microresonator that would have a high value of the resonance quality factor (Q . 107). The surface of each microresonator would be derivatized to make it bind molecules of a species of interest, and such binding would introduce a measurable change in the optical properties of the microresonator. Because each microresonator could be derivatized for detection of a specific biochemical different from those of the other microresonators, it would be possible to detect multiple specific biochemicals by simultaneous or sequential interrogation of all the elements in the array. Moreover, the derivatization would make it unnecessary to prepare samples by chemical tagging. Such interrogation would be effected by means of a grid of row and column polymer-based optical waveguides that would be integral parts of a chip on which the array would be fabricated. The row and column polymer-based optical waveguides would intersect at the elements of the array (see figure). At each intersection, the row and column waveguides would be optically coupled to one of the microresonators. The polymer-based waveguides would be connected via optical fibers to external light sources and photodetectors. One set of waveguides and fibers (e.g., the row waveguides and fibers) would couple light from the sources to the resonators; the other set of waveguides and fibers (e.g., the column waveguides and fibers) would couple light from the microresonators to the photodetectors. Each microresonator could be addressed individually by row and column for measurement of its optical transmission. Optionally, the chip could be fabricated so that each microresonator would lie inside a microwell, into which a microscopic liquid sample could be dispensed.

Iltchenko, Vladimir; Maleki, Lute; Lin, Ying; Le, Thanh

2009-01-01

158

Infrared detector arrays with integrating cryogenic read-out electronics  

NASA Astrophysics Data System (ADS)

Depending on the application different types of integrating cryogenic read out electronics are used for extrinsic photoconductive detectors and detector arrays. They integrate the current flowing through the detector during a given integration time by charging a capacity. To test the different detector units with respect to their sensitivity different evaluation methods are used for the determination of the noise produced by the whole assembly. To evaluate its amount different methods of signal processing as non destructive read out (NDR), correlated double sampling (CDS) and data averaging are implemented. The different methods of signal and data processing used for the tests of the detector units as well as results obtained at selected detector assemblies are presented and discussed.

Engemann, D.; Faymonville, R.; Felten, R.; Frenzl, O.

1991-02-01

159

High-energy interactions in kinetic inductance detectors arrays  

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

160

Uncooled Detectors Challenges for THz/sub-THz Arrays Imaging  

NASA Astrophysics Data System (ADS)

Some problems and challenges for applications of uncooled or slightly cooled detectors (not deeper than to 77 K) for sub-THz and THz (terahertz) arrays are briefly discussed. The possibilities to involve detectors based on plasmon resonance FETs (field effect transistors) and those based on warm electron effect narrow-gap semiconductor bolometers are speculated, as they seem to be promising for using in large format broadband arrays of low-cost systems, though they are still in the stage of research and optimization.

Sizov, Fiodor F.; Reva, Vladimir P.; Golenkov, Alexandr G.; Zabudsky, Vyacheslav V.

2011-10-01

161

SRAM As An Array Of Energetic-Ion Detectors  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

162

Cosmic rays studied with a hybrid high school detector array  

E-print Network

The LORUN/NAHSA system is a pathfinder for hybrid cosmic ray research combined with education and outreach in the field of astro-particle physics. Particle detectors and radio antennae were mainly setup by students and placed on public buildings. After fully digital data acquisition, coincidence detections were selected. Three candidate events confirmed a working prototype, which can be multiplied to extend further particle detector arrays on high schools.

A. Nigl; C. Timmermans; P. Schellart; J. Kuijpers; H. Falcke; A. Horneffer; C. M. de Vos; Y. Koopman; H. J. Pepping; G. Schoonderbeek

2008-09-16

163

New 36-Element Pixel Array Detector at the ANBF - Choosing the Right Detector for your Beamline  

SciTech Connect

The Pixel Array Detector for XAFS data collection recently commissioned at the Australian National Beamline Facility is well matched to a busy second-generation bending magnet source where both high and low-flux applications are routinely encountered. In combination with the digital counting chain, throughput has improved by approximately a factor of 5. Detector resolution deteriorates slightly at high count rates.

Foran, Garry; Hester, James [Australian Synchrotron Research Program, KEK-PF, Oho 1-1, Tsukuba, Ibaraki, 3050801 (Japan); Garrett, Richard [Australian Synchrotron Research Program, KEK-PF, Oho 1-1, Tsukuba, Ibaraki, 3050801 (Japan); ANSTO, PMBI, Menai, NSW 2234 (Australia); Dressler, Pierre; Fonne, Charles; Beau, Jean-Olivier; Lampert, Marie-Odile [Canberra-Eurisys, 1, chemin de la Roseraie, Parc des Tanneries, 67380 Lingolsheim (France)

2007-01-19

164

Recent advances in avalanche photodiodes  

Microsoft Academic Search

In this paper we review recent advancements in the performance of avalanche photodiodes (APDs). APDs designed for fiber optic receivers, low-level ultra-violet detection, and Geiger-mode single photon detectors will be discussed.

J. C. Campbell

2008-01-01

165

Separation of picrocrocin, cis-trans-crocins and safranal of saffron using high-performance liquid chromatography with photodiode-array detection.  

PubMed

High-performance liquid chromatography with photodiode-array detection was used to separate picrocrocin (bitter-tasting component, glucoside of safranal), cis/trans-crocins (carotenoids, glucosyl esters of crocetin) and safranal (flavour, monoterpene aldehyde) of saffron. All components of pure red Greek saffron were extracted from dried stigma with 50% methanol. These compounds were detected, separated collected and identified simultaneously using a Merck LiChroCART 125-4 Superspher 100 RP-18 (4 microns) column and as mobile phase a linear gradient from 20% to 100% acetonitrile in water in 20 min with a detection wavelength at 308 nm. PMID:8012549

Tarantilis, P A; Polissiou, M; Manfait, M

1994-03-25

166

Simultaneous analysis of anthocyanins and flavonols in petals of lotus (Nelumbo) cultivars by high-performance liquid chromatography-photodiode array detection/electrospray ionization mass spectrometry.  

PubMed

A fast and reliable HPLC method for the simultaneous separation of anthocyanins and flavonols in lotus petals was developed based on the study of four candidate solvent systems. Fifteen flavonoids were identified by high-performance liquid chromatography with photodiode array detection/mass spectrometry. Among them, two anthocyanins and nine flavonols were discovered in lotus petals for the first time. This work is valuable for both the hybrid breeding on lotus oriented to flower color and the utilization of lotus petals as functional food materials. PMID:19062023

Yang, Rui-Zhen; Wei, Xiao-Lei; Gao, Fen-Fang; Wang, Liang-Sheng; Zhang, Hui-Jin; Xu, Yan-Jun; Li, Chong-Hui; Ge, Yu-Xuan; Zhang, Jing-Jing; Zhang, Jie

2009-01-01

167

An Event Reconstruction Method for the Telescope Array Fluorescence Detectors  

SciTech Connect

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.

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

168

Veto Detectors for the Micro-Modular Neutron Array  

NASA Astrophysics Data System (ADS)

Current neutron detectors at the National Superconducting Cyclotron Laboratory have a detection efficiency of ten percent for single neutron hits and one percent for double neutron hits. The Modular Neutron Array (MoNA), a large-area neutron detector consisting of 144 individual plastic scintillator modules, will have detection efficiencies of seventy percent for single neutron hits and nearly fifty percent for double neutron hits. MoNA will measure the energy of neutrons by time-of-flight relative to a start detector and the position by the time difference of the signals between both ends. Tests were conducted on a small subset of MoNA, ?MoNA, that consisted of eight MoNA detector bars. Two veto detectors placed in front of ?MoNA were used in these first test experiments where neutrons and charged particles were produced from high-energy ^36Ar and ^8Li beams. The veto detectors discriminated between neutrons and charged particles that hit the array following a reaction of the beam. The veto detectors were very thin, so most neutrons passed through them and into the modules without losing energy. However, the charged particles were easily identifiable when they passed through the veto paddles, allowing the differentiation between actual neutron events and background events of charged particles.

Lu, Yao; Baumann, Thomas; Thoennessen, Michael; Tryggestad, Erik; Evanger, Melanie; Luther, Bryan; Rajabali, Mustafa; Turner, Ramsey

2002-10-01

169

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

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

170

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

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

171

Plans for CHICOS a detector array in California High Schools  

Microsoft Academic Search

The California HIgh school Cosmic ray ObServatory, CHICOS, is a collabora-tive project involving Caltech, Cal State Northridge, UC Irvine, and local high school physics teachers to site a large array of particle detectors at high schools in the Los Angeles area. The Los Angeles basin is quite unique in that there is a very large area (> 5000 km2 )

R. D. McKeown; R. Carr; J. Gao; T. Guerrera; S. Horton-Smith; T. Ito; R. Seki; S.-P. Li; A. Shoup; G. Yodh

2001-01-01

172

Conceptual design of a hybrid Ge:Ga detector array  

NASA Technical Reports Server (NTRS)

For potential applications in space infrared astronomy missions such as the Space Infrared Telescope Facility and the Large Deployable Reflector, integrated arrays of long-wavelength detectors are desired. The results of a feasibility study which developed a design for applying integrated array techniques to a long-wavelength (gallium-doped germanium) material to achieve spectral coverage between 30 and 200 microns are presented. An approach which builds up a two-dimensional array by stacking linear detector modules is presented. The spectral response of the Ge:Ga detectors is extended to 200 microns by application of uniaxial stress to the stack of modules. The detectors are assembled with 1 mm spacing between the elements. Multiplexed readout of each module is accomplished with integration sampling of a metal-oxide-semiconductor (MOS) switch chip. Aspects of the overall design, including the anticipated level of particle effects on the array in the space environment, a transparent electrode design for 200 microns response, estimates of optical crosstalk, and mechanical stress design calculations are included.

Parry, C. M.

1984-01-01

173

High resolution decoding of Multi-Anode Microchannel Array detectors  

NASA Astrophysics Data System (ADS)

The Multi-Anode Microchannel Array (MAMA) is a photon counting detector which utilizes a photocathode for photon to electron conversion, a microchannel plate (MCP) for signal amplification and a proximity focused anode array for position sensitivity. The detector electronics decode the position of an event through coincidence discrimination. The decoding algorithm which associates a given event with the appropriate pixel is determined by the geometry of the array. A new algorithm incorporated into a CMOS Application Specific Integrated Circuit (ASIC) decoder which improves the pixel spatial resolution is described. The new algorithm does not degrade the detector throughput and does not require any modifications to the detector tube. The standard MAMA detector has a pixel size of 25 x 25 square microns, but with the new decoder circuit the pixel size is reduced to 12.5 x 12.5 square microns. We have built the first set of decode electronics utilizing the new ASIC chips and report here on the first imaging tests of this system.

Kasle, David B.; Morgan, Jeffrey S.

1991-10-01

174

Keck array and BICEP3: spectral characterization of 5000+ detectors  

NASA Astrophysics Data System (ADS)

The inflationary paradigm of the early universe predicts a stochastic background of gravitational waves which would generate a B-mode polarization pattern in the cosmic microwave background (CMB) at degree angular scales. Precise measurement of B-modes is one of the most compelling observational goals in modern cosmology. Since 2011, the Keck Array has deployed over 2500 transition edge sensor (TES) bolometer detectors at 100 and 150 GHz to the South Pole in pursuit of degree-scale B-modes, and Bicep3 will follow in 2015 with 2500 more at 100 GHz. Characterizing the spectral response of these detectors is important for controlling systematic effects that could lead to leakage from the temperature to polarization signal, and for understanding potential coupling to atmospheric and astrophysical emission lines. We present complete spectral characterization of the Keck Array detectors, made with a Martin-Puplett Fourier Transform Spectrometer at the South Pole, and preliminary spectra of Bicep3 detectors taken in lab. We show band centers and effective bandwidths for both Keck Array bands, and use models of the atmosphere at the South Pole to cross check our absolute calibration. Our procedure for obtaining interferograms in the field with automated 4-axis coupling to the focal plane represents an important step towards efficient and complete spectral characterization of next-generation instruments more than 10000 detectors.

Karkare, K. S.; Ade, P. A. R.; Ahmed, Z.; Aikin, R. W.; Alexander, K. D.; Amiri, M.; Barkats, D.; Benton, S. J.; Bischoff, C. A.; Bock, J. J.; Bonetti, J. A.; Brevik, J. A.; Buder, I.; Bullock, E. W.; Burger, B.; Connors, J.; Crill, B. P.; Davis, G.; Dowell, C. D.; Duband, L.; Filippini, J. P.; Fliescher, S. T.; Golwala, S. R.; Gordon, M. S.; Grayson, J. A.; Halpern, M.; Hasselfield, M.; Hildebrandt, S. R.; Hilton, G. C.; Hristov, V. V.; Hui, H.; Irwin, K. D.; Kang, J. H.; Karpel, E.; Kefeli, S.; Kernasovskiy, S. A.; Kovac, J. M.; Kuo, C. L.; Leitch, E. M.; Lueker, M.; Mason, P.; Megerian, K. G.; Netterfield, C. B.; Nguyen, H. T.; O'Brient, R.; Ogburn, R. W.; Pryke, C. L.; Reintsema, C. D.; Richter, S.; Schwarz, R.; Sheehy, C. D.; Staniszewski, Z. K.; Sudiwala, R. V.; Teply, G. P.; Thompson, K. L.; Tolan, J. E.; Turner, A. D.; Vieregg, A.; Weber, A.; Wong, C. L.; Wu, W. L. K.; Yoon, K. W.

2014-08-01

175

Signal Attenuation Curve for Different Surface Detector Arrays  

NASA Astrophysics Data System (ADS)

Modern cosmic ray experiments consisting of large array of particle detectors measure the signals of electromagnetic or muon components or their combination. The correction for an amount of atmosphere passed is applied to the surface detector signal before its conversion to the shower energy. Either Monte Carlo based approach assuming certain composition of primaries or indirect estimation using real data and assuming isotropy of arrival directions can be used. Toy surface arrays of different sensitivities to electromagnetic and muon components are assumed in MC simulations to study effects imposed on attenuation curves for varying composition or possible high energy anisotropy. The possible sensitivity of the attenuation curve to the mass composition is also tested for different array types focusing on a future apparatus that can separate muon and electromagnetic component signals.

Vicha, J.; Travnicek, P.; Nosek, D.; Ebr, J.

2014-06-01

176

A readout for large arrays of microwave kinetic inductance detectors  

NASA Astrophysics Data System (ADS)

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.

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

2012-04-01

177

Experimental realization of a metamaterial detector focal plane array.  

PubMed

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

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

2012-10-26

178

Applications of pyroelectric materials in array-based detectors.  

PubMed

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

Holden, Anthony J

2011-09-01

179

Prototype Imaging Cd-Zn-Te Array Detector  

E-print Network

We describe initial results of our program to develop and test Cd-Zn-Te (CZT) detectors with a pixellated array readout. Our primary interest is in the development of relatively thick CZT detectors for use in astrophysical coded aperture telescopes with response extending over the energy range $\\sim 10-600$ keV. The coded aperture imaging configuration requires only relatively large area pixels (1-3 mm), whereas the desired high energy response requires detector thicknesses of at least 3-5 mm. We have developed a prototype detector employing a 10 x 10 x 5 mm CZT substrate and 4 x 4 pixel (1.5 mm each) readout with gold metal contacts for the pixels and continuous gold contact for the bias on the opposite detector face. This MSM contact configuration was fabricated by RMD and tested at Harvard for uniformity, efficiency and spatial as well as spectral resolution. We have developed an ASIC readout (IDE-VA-1) and analysis system and report results, including $\\sim 4$% (FWHM) energy resolution at 60 keV. A prototype design for a full imaging detector array is discussed.

P. F. Bloser; T. Narita; J. E. Grindlay; K. Shah

1998-01-15

180

Determination of sulphonated azo dyes in food by ion-pair liquid chromatography with photodiode array and electrospray mass spectrometry detection.  

PubMed

An ion-pair liquid chromatography method with on-line photodiode-array and electrospray mass spectrometry detection was developed to determine 10 commonly used sulphonated azo dyes (Tartrazine, Amaranth, New Coccine, Sunset Yellow FCF, Allura Red AC, Ponceau R, Ponceau 3R, Orange I, Orange II and Metanil Yellow) in food. A reversed phase C(18) column with gradient elution was utilized to separate these compounds. Triethylamine was added in the mobile phase as an ion-pair reagent for chromatographic separation. Photodiode-array detection was employed for quantitative determination and electrospray mass spectrometry was used for identification. Good linearity (0.05-10 ppm, r(2)=0.999) and detection limit (<0.01 ppm) were determined with 5 mul injection. In addition, precision and accuracy associated with this newly developed method will be presented. A liquid extraction method was also developed to extract these dyes from different foodstuffs. The application of this method was demonstrated by analyzing sulphonated azo dyes in soft drinks, fruit jam, and salted vegetables. PMID:18968541

Fuh, Ming-Ren; Chia, Kan-Jung

2002-03-11

181

Calibration and operational data for a compact photodiode detector useful for monitoring the location of moving sources of positron emitting radioisotopes  

NASA Astrophysics Data System (ADS)

D-Pace has developed a compact cost-effective gamma detector system based on technology licensed from TRIUMF [1]. These photodiode detectors are convenient for detecting the presence of positron emitting radioisotopes, particularly for the case of transport of radioisotopes from a PET cyclotron to hotlab, or from one location to another in an automated radiochemistry processing unit. This paper describes recent calibration experiments undertaken at the Turku PET Centre for stationary and moving sources of F18 and C11 in standard setups. The practical diagnostic utility of using several of these devices to track the transport of radioisotopes from the cyclotron to hotlab is illustrated. For example, such a detector system provides: a semi-quantitative indication of total activity, speed of transport, location of any activity lost en route and effectiveness of follow-up system flushes, a means of identifying bolus break-up, feedback useful for deciding when to change out tubing.

Marsland, M. G.; Dehnel, M. P.; Johansson, S.; Rajander, J.; Solin, O.; Theroux, J.; Stewart, T. M.; Christensen, T.; Hollinger, C.

2013-04-01

182

Order-sorting filter transmittance measured with an array detector  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

183

The NSLS 100 element solid state array detector  

SciTech Connect

X-ray absorption studies of dilute samples require fluorescence detection techniques. Since signal-to-noise ratios are governed by the ratio of fluorescent to scattered photons counted by a detector, solid state detectors which can discriminate between fluorescence and scattered photons have become the instruments of choice for trace element measurements. Commercially available 13 element Ge array detectors permitting total count rates < 500,000 counts per second are now in routine use. Since x-ray absorption beamlines at high brightness synchrotron sources can already illuminate most dilute samples with enough flux to saturate the current generation of solid state detectors, the development of next-generation instruments with significantly higher total count rates is essential. We present the design and current status of the 100 element Si array detector being developed in a collaboration between the NSLS and the Instrumentation Division at Brookhaven National Laboratory. The detecting array consists of a 10*10 matrix of 4mm * 4mm elements laid out on a single piece of ultra-high purity silicon mounted at the front end of a liquid nitrogen dewar assembly. A matrix of charge sensitive integrating preamplifiers feed signals to an array of shaping amplifiers, single channel analyzers, and scalers. An electronic switch, delay amplifier, linear gate, digital scope, peak sensing A to D converter, and histogramming memory module provide for complete diagnostics and channel calibration. The entire instrument is controlled by a LabView 2 application on a MacII ci; the software also provides full control over beamline hardware and performs the data collection.

Furenlid, L.R.; Kraner, H.W.; Rogers, L.C.; Stephani, D.; Beuttenmuller, R.H.; Beren, J. (Brookhaven National Lab., Upton, NY (United States)); Cramer, S.P. (California Univ., Davis, CA (United States). Dept. of Applied Science)

1991-01-01

184

The NSLS 100 element solid state array detector  

SciTech Connect

X-ray absorption studies of dilute samples require fluorescence detection techniques. Since signal-to-noise ratios are governed by the ratio of fluorescent to scattered photons counted by a detector, solid state detectors which can discriminate between fluorescence and scattered photons have become the instruments of choice for trace element measurements. Commercially available 13 element Ge array detectors permitting total count rates < 500,000 counts per second are now in routine use. Since x-ray absorption beamlines at high brightness synchrotron sources can already illuminate most dilute samples with enough flux to saturate the current generation of solid state detectors, the development of next-generation instruments with significantly higher total count rates is essential. We present the design and current status of the 100 element Si array detector being developed in a collaboration between the NSLS and the Instrumentation Division at Brookhaven National Laboratory. The detecting array consists of a 10*10 matrix of 4mm * 4mm elements laid out on a single piece of ultra-high purity silicon mounted at the front end of a liquid nitrogen dewar assembly. A matrix of charge sensitive integrating preamplifiers feed signals to an array of shaping amplifiers, single channel analyzers, and scalers. An electronic switch, delay amplifier, linear gate, digital scope, peak sensing A to D converter, and histogramming memory module provide for complete diagnostics and channel calibration. The entire instrument is controlled by a LabView 2 application on a MacII ci; the software also provides full control over beamline hardware and performs the data collection.

Furenlid, L.R.; Kraner, H.W.; Rogers, L.C.; Stephani, D.; Beuttenmuller, R.H.; Beren, J. [Brookhaven National Lab., Upton, NY (United States); Cramer, S.P. [California Univ., Davis, CA (United States). Dept. of Applied Science

1991-12-31

185

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

Microsoft Academic Search

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

G. V. Poropat

1992-01-01

186

Charge-coupled CMOS and hybrid detector arrays  

NASA Astrophysics Data System (ADS)

Over a decade has passed since complementary metal oxide semiconductor (CMOS) imaging detectors made their move into the charge-coupled device (CCD) arena. Low cost, low power, on-chip system integration, high-speed operation and tolerance to high-energy radiation sources are unique features that make CMOS detectors popular. However, it remains unclear if CMOS arrays can compete with the CCD in high performance applications (e.g., scientific). This paper compares fundamental performance parameters common to both CMOS and CCD imagers, and lists specific SMOS performance deficiencies that prevent the technology from high end use. In this paper we will present custom CMOS pixel designs and related fabrication processes that solve most deficiencies. We will also discuss "hybrid" imaging arrays that marry the advantages of CCD and CMOS producing sensors with superior performance in comparison to CCD and CMOS bulk monolithic sensors. CCD to CMOS, CMOS to CMOS and CMOS SOI hybrids are reviewed.

Janesick, James R.

2004-01-01

187

A 90 element CdTe array detector  

Microsoft Academic Search

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

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

1992-01-01

188

A current mode detector array for ? -ray asymmetry measurements  

Microsoft Academic Search

We have built a CsI(Tl) ?-ray detector array for the NPDGamma experiment to search for a small parity-violating directional asymmetry in the angular distribution of 2.2MeV ?-rays from the capture of polarized cold neutrons by protons with a sensitivity of several ppb. The weak pion–nucleon coupling constant can be determined from this asymmetry. The small size of the asymmetry requires

M. T. Gericke; C. Blessinger; J. D. Bowman; R. C. Gillis; J. Hartfield; T. Ino; M. Leuschner; Y. Masuda; G. S. Mitchell; S. Muto; H. Nann; S. A. Page; S. I. Penttilä; W. D. Ramsay; P.-N. Seo; W. M. Snow; J. Tasson; W. S. Wilburn

2005-01-01

189

Pyroelectric linear array IR detectors with CCD multiplexer  

Microsoft Academic Search

Responsive pyroelectric linear arrays are described. After a short representation of the principal detector function, the pyroelectric materials L-alanine doped triglycine sulfate (DTGS:L-A) and lithium niobate (LiNbO3) are characterized, and the system parts pyroelectric chip, CCD-multiplexer, and hybrid arrangement are described in detail. Finally, the measured properties responsivity, noise equivalent power, and modulation transfer function are summarized.

Volkmar Norkus; Norbert Neumann; Ludwig Walther; Guenter Hofmann; Jorg Schieferdecker; Matthias G. Krauss; Helmut Budzier; Norbert Hess

1991-01-01

190

Pyroelectric linear array IR detectors with CCD multiplexer  

NASA Astrophysics Data System (ADS)

Responsive pyroelectric linear arrays are described. After a short representation of the principal detector function, the pyroelectric materials L-alanine doped triglycine sulfate (DTGS:L-A) and lithium niobate (LiNbO3) are characterized, and the system parts pyroelectric chip, CCD-multiplexer, and hybrid arrangement are described in detail. Finally, the measured properties responsivity, noise equivalent power, and modulation transfer function are summarized.

Norkus, Volkmar; Neumann, Norbert; Walther, Ludwig; Hofmann, Guenter; Schieferdecker, Jorg; Krauss, Matthias G.; Budzier, Helmut; Hess, Norbert

1991-08-01

191

The Telescope Array Middle Drum fluorescence detector simulation on GPUs  

NASA Astrophysics Data System (ADS)

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.

Abu-Zayyad, Tareq; Telescope-Array Collaboration

2014-06-01

192

READOUT SYSTEM FOR ARRAYS OF FRISCH-RING CDZNTE DETECTORS.  

SciTech Connect

Frisch-ring CdZnTe detectors have demonstrated good energy resolution for identifying isotopes, <1% FWHM at 662 keV, and good efficiency for detecting gamma rays. We will fabricate and test at Brookhaven National Laboratory an integrated module of a 64-element array of 6 x 6 x 12 mm{sup 3} Frisch-ring detectors, coupled with a readout electronics system. It supports 64 readout channels, and includes front-end electronics, signal processing circuit, USB interface and high-voltage power supply. The data-acquisition software is used to process the data stream, which includes amplitude and timing information for each detected event. This paper describes the design and assembly of the detector modules, readout electronics, and a conceptual prototype system. Some test results are also reported.

CUI, Y.; BOLOTNIKOV, A.E.; CAMARDA, G.S.; DE GERONIMO, G.; O'CONNOR, P.; JAMES, R.B.; KARGAR, A.; HARRISON, M.J.; MCGREGOR, D.S.

2006-10-29

193

Autofocus technique for three-dimensional imaging, direct-detection laser radar using Geiger-mode avalanche photodiode focal-plane array.  

PubMed

An autofocus technique is proposed for a three-dimensional imaging, direct-detection laser radar system that uses a Geiger-mode avalanche photodiode focal plane array (GmAPD-FPA). This technique is implemented by pointing laser pulses on a target of interest and observing its scattered photon distribution on a GmAPD-FPA. Measuring the standard deviation of the photon distribution on a GmAPD-FPA enables the best focus condition to be found. The feasibility of this technique is demonstrated experimentally by employing a 1 × 8 pixel GmAPD-FPA. It is shown that the spatial resolution improves when the GmAPD-FPA is located in the best focus position found by the autofocus technique. PMID:21165141

Oh, Min Seok; Kong, Hong Jin; Kim, Tae Hoon; Jo, Sung Eun

2010-12-15

194

SiC avalanche photodiodes  

Microsoft Academic Search

Ultraviolet detectors are becoming increasingly important in medical, military, and environmental applications, including biological agent detection and non-line-of-sight (NLOS) communications. SiC avalanche photodiodes (APDs) are an attractive candidate for those applications that place a premium on detectors that are compact, rugged, and inexpensive. This paper presents an overview of 4H-SiC APDs.

J. C. Campbell; Han-Din Liu; D. Mcintosh; Xiaogang Bai

2007-01-01

195

Design of a silicon avalanche photodiode pixel with integrated laser diode using back-illuminated crystallographically etched silicon-on-sapphire with monolithically integrated microlens for dual-mode passive and active imaging arrays  

NASA Astrophysics Data System (ADS)

There is a growing need in scientific research applications for dual-mode, passive and active 2D and 3D LADAR imaging methods. To fill this need, an advanced back-illuminated silicon avalanche photodiode (APD) design is presented using a novel silicon-on-sapphire substrate incorporating a crystalline aluminum nitride (AlN) antireflective layer between the silicon and R-plane sapphire. This allows integration of a high quantum efficiency silicon APD with a gallium nitride (GaN) laser diode in each pixel. The pixel design enables single photon sensitive, solid-state focal plane arrays (FPAs) with wide dynamic range, supporting passive and active imaging capability in a single FPA. When (100) silicon is properly etched with TMAH solution, square based pyramidal frustum or mesa arrays result with the four mesa sidewalls of the APD formed by (111) silicon planes that intersect the (100) planes at a crystallographic angle, ? c = 54.7°. The APD device is fabricated in the mesa using conventional silicon processing technology. The GaN laser diode is fabricated by epitaxial growth inside of an inverted, etched cavity in the silicon mesa. Microlenses are fabricated in the thinned, and AR-coated sapphire substrate. The APDs share a common, front-side anode contact, and laser diodes share a common cathode. A low resistance (Al) or (Cu) metal anode grid fills the space between pixels and also inhibits optical crosstalk. SOS-APD arrays are flip-chip bump-bonded to CMOS readout ICs to produce hybrid FPAs. The square 27 ?m emitter-detector pixel achieves SNR > 1 in active detection mode for Lambert surfaces at 1,000 meters.

Stern, Alvin G.

2010-08-01

196

Design of micro-sensor-array detector for toxic gas  

NASA Astrophysics Data System (ADS)

To quickly measure the trace concentration of the single component toxic gas (e.g. sarin), a micro-array toxic gas detector is designed. A 3 x 3 gas sensor array with metalloporphyrins as sensitive materials is introduced. A micro-capsule that can be easy to be loaded and unloaded is designed for the gas reaction. A fiber-array optical path is designed, which is based on the principle that gas sensors will show different colors after reaction with the toxic gas. The tricolor information about the concentration of gas is collected by the color liner CCD. A control handling system with C8051F021 MCU as the core is implemented and embedded into the detector to perform the functions of gas sampling, data collection and analysis calculation. Data acquisition experimental results show that the proposed scheme can effectively collect the color information after gas reaction. Moreover, the system has many important advantages, such as small size, compact structure, high degree of automation, fast detection speed and high performance-cost ratio, etc.

Liao, Hai-yang; Tian, Peng

2010-08-01

197

Novel Multiplexing Technique for Detector and Mixer Arrays  

NASA Technical Reports Server (NTRS)

Future submillimeter and far-infrared space telescopes will require large-format (many 1000's of elements) imaging detector arrays to perform state-of-the-art astronomical observations. A crucial issue related to a focal plane array is a readout scheme which is compatible with large numbers of cryogenically-cooled (typically < 1 K) detectors elements. When the number of elements becomes of the order of thousands, the physical layout for individual readout amplifiers becomes nearly impossible to realize for practical systems. Another important concern is the large number of wires leading to a 0.1-0.3 K platform. In the case of superconducting transition edge sensors (TES), a scheme for time-division multiplexing of SQUID read-out amplifiers has been recently demonstrated. In this scheme the number of SQUIDs is equal to the number (N) of the detectors, but only one SQUID is turned on at a time. The SQUIDs are connected in series in each column of the array, so the number of wires leading to the amplifiers can be reduced, but it is still of the order of N. Another approach uses a frequency domain multiplexing scheme of the bolometer array. The bolometers are biased with ac currents whose frequencies are individual for each element and are much higher than the bolometer bandwidth. The output signals are connected in series in a summing loop which is coupled to a single SQUID amplifier. The total number of channels depends on the ratio between the SQUID bandwidth and the bolometer bandwidth and can be at least 100 according to the authors. An important concern about this technique is a contribution of the out-of-band Johnson noise which multiplies by factor N(exp 1/2) for each frequency channel. We propose a novel solution for large format arrays based on the Hadamard transform coding technique which requires only one amplifier to read out the entire array of potentially many 1000's of elements and uses approximately 10 wires between the cold stage and room temperature electronics. This can significantly reduce the complexity of the readout circuits.

Karasik, Boris S.; McGrath, William R.

2001-01-01

198

Design of HgCdTe heterojunction photodiodes on Si substrate  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

199

An MLC calibration method using a detector array  

SciTech Connect

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.

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

200

An MLC calibration method using a detector array  

PubMed Central

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. PMID:19928080

Simon, Thomas A.; Kahler, Darren; Simon, William E.; Fox, Christopher; Li, Jonathan; Palta, Jatinder; Liu, Chihray

2009-01-01

201

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

Microsoft Academic Search

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

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

2002-01-01

202

Photon-counting detector arrays based on microchannel array plates. [for image enhancement  

NASA Technical Reports Server (NTRS)

The recent development of the channel electron multiplier (CEM) and its miniaturization into the microchannel array plate (MCP) offers the possibility of fully combining the advantages of the photographic and photoelectric detection systems. The MCP has an image-intensifying capability and the potential of being developed to yield signal outputs superior to those of conventional photomultipliers. In particular, the MCP has a photon-counting capability with a negligible dark-count rate. Furthermore, the MCP can operate stably and efficiently at extreme-ultraviolet and soft X-ray wavelengths in a windowless configuration or can be integrated with a photo-cathode in a sealed tube for use at ultraviolet and visible wavelengths. The operation of one- and two-dimensional photon-counting detector arrays based on the MCP at extreme-ultraviolet wavelengths is described, and the design of sealed arrays for use at ultraviolet and visible wavelengths is briefly discussed.

Timothy, J. G.

1975-01-01

203

Multispectral breast imaging using a ten-wavelength, 64x64 source/detector channels silicon photodiode-based diffuse optical tomography system  

SciTech Connect

We describe a compact diffuse optical tomography system specifically designed for breast imaging. The system consists of 64 silicon photodiode detectors, 64 excitation points, and 10 diode lasers in the near-infrared region, allowing multispectral, three-dimensional optical imaging of breast tissue. We also detail the system performance and optimization through a calibration procedure. The system is evaluated using tissue-like phantom experiments and an in vivo clinic experiment. Quantitative two-dimensional (2D) and three-dimensional (3D) images of absorption and reduced scattering coefficients are obtained from these experiments. The ten-wavelength spectra of the extracted reduced scattering coefficient enable quantitative morphological images to be reconstructed with this system. From the in vivo clinic experiment, functional images including deoxyhemoglobin, oxyhemoglobin, and water concentration are recovered and tumors are detected with correct size and position compared with the mammography.

Li Changqing; Zhao Hongzhi; Anderson, Bonnie; Jiang Huabei [Department of Biomedical Engineering, University of Florida, Gainesville, Florida 32611-6131 (United States); Department of Radiology, Oconee Memorial Hospital, Seneca, South Carolina 29672 (United States); Department of Biomedical Engineering, University of Florida, Gainesville, Florida 32611-6131 (United States)

2006-03-15

204

Advanced Antenna-Coupled Superconducting Detector Arrays for CMB Polarimetry  

NASA Astrophysics Data System (ADS)

We are developing high-sensitivity millimeter-wave detector arrays for measuring the polarization of the cosmic microwave background (CMB). This development is directed to advance the technology readiness of the Inflation Probe mission in NASA's Physics of the Cosmos program. The Inflation Probe is a fourth-generation CMB satellite that will measure the polarization of the CMB to astrophysical limits, characterizing the inflationary polarization signal, mapping large-scale structure based on polarization induced by gravitational lensing, and mapping Galactic magnetic fields through measurements of polarized dust emission. The inflationary polarization signal is produced by a background of gravitational waves from the epoch of inflation, an exponential expansion of space-time in the early universe, with an amplitude that depends on the physical mechanism producing inflation. The inflationary polarization signal may be distinguished by its unique 'B-mode' vector properties from polarization from the density variations that predominantly source CMB temperature anisotropy. Mission concepts for the Inflation Probe are being developed in the US, Europe and Japan. The arrays are based on planar antennas that provide integral beam collimation, polarization analysis, and spectral band definition in a compact lithographed format that eliminates discrete fore-optics such as lenses and feedhorns. The antennas are coupled to transition-edge superconducting bolometers, read out with multiplexed SQUID current amplifiers. The superconducting sensors and readouts developed in this program share common technologies with NASA X-ray and FIR detector applications. Our program targets developments required for space observations, and we discuss our technical progress over the past two years and plans for future development. We are incorporating arrays into active sub-orbital and ground-based experiments, which advance technology readiness while producing state of the art CMB polarization measurements.

Bock, James

2014-01-01

205

Capillary Array Waveguide Amplified Fluorescence Detector for mHealth  

PubMed Central

Mobile Health (mHealth) analytical technologies are potentially useful for carrying out modern medical diagnostics in resource-poor settings. Effective mHealth devices for underserved populations need to be simple, low cost, and portable. Although cell phone cameras have been used for biodetection, their sensitivity is a limiting factor because currently it is too low to be effective for many mHealth applications, which depend on detection of weak fluorescent signals. To improve the sensitivity of portable phones, a capillary tube array was developed to amplify fluorescence signals using their waveguide properties. An array configured with 36 capillary tubes was demonstrated to have a ~100X increase in sensitivity, lowering the limit of detection (LOD) of mobile phones from 1000 nM to 10 nM for fluorescein. To confirm that the amplification was due to waveguide behavior, we coated the external surfaces of the capillaries with silver. The silver coating interfered with the waveguide behavior and diminished the fluorescence signal, thereby proving that the waveguide behavior was the main mechanism for enhancing optical sensitivity. The optical configuration described here is novel in several ways. First, the use of capillaries waveguide properties to improve detection of weak florescence signal is new. Second we describe here a three dimensional illumination system, while conventional angular laser waveguide illumination is spot (or line), which is functionally one-dimensional illumination, can illuminate only a single capillary or a single column (when a line generator is used) of capillaries and thus inherently limits the multiplexing capability of detection. The planar illumination demonstrated in this work enables illumination of a two dimensional capillary array (e.g. x columns and y rows of capillaries). In addition, the waveguide light propagation via the capillary wall provides a third dimension for illumination along the axis of the capillaries. Such an array can potentially be used for sensitive analysis of multiple fluorescent detection assays simultaneously. The simple phone based capillary array approach presented in this paper is capable of amplifying weak fluorescent signals thereby improving the sensitivity of optical detectors based on mobile phones. This may allow sensitive biological assays to be measured with low sensitivity detectors and may make mHealth practical for many diagnostics applications, especially in resource-poor and global health settings. PMID:24039345

Balsam, Joshua; Bruck, Hugh Alan; Rasooly, Avraham

2013-01-01

206

Antenna coupled detectors for 2D staring focal plane arrays  

NASA Astrophysics Data System (ADS)

Millimeter-wave (mmW)/sub-mmW/THz region of the electro-magnetic spectrum enables imaging thru clothing and other obscurants such as fog, clouds, smoke, sand, and dust. Therefore considerable interest exists in developing low cost millimeter-wave imaging (MMWI) systems. Previous MMWI systems have evolved from crude mechanically scanned, single element receiver systems into very complex multiple receiver camera systems. Initial systems required many expensive mmW integrated-circuit low-noise amplifiers. In order to reduce the cost and complexity of the existing systems, attempts have been made to develop new mmW imaging sensors employing direct detection arrays. In this paper, we report on Raytheon's recent development of a unique focal plane array technology, which operates broadly from the mmW through the sub-mmW/THz region. Raytheon's innovative nano-antenna based detector enables low cost production of 2D staring mmW focal plane arrays (mmW FPA), which not only have equivalent sensitivity and performance to existing MMWI systems, but require no mechanical scanning.

Gritz, Michael A.; Kolasa, Borys; Lail, Brian; Burkholder, Robert; Chen, Leonard

2013-06-01

207

IDENTIFICATION AND QUANTITATION OF ALKYLATED NUCLEOBASIS BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY WITH UV PHOTODIODE ARRAY DETECTION  

EPA Science Inventory

The application of UV diode array detection in high-performance liquid chromatographic (HPLC) identification and quantitation of several classes of synthetic and commercially available alkylated nucleobases is investigated. uantitative spectral overlays of these compounds to meth...

208

Time-dependent photon number discrimination of InGaAs/InP avalanche photodiode single-photon detector.  

PubMed

We investigated the photon-number-resolving (PNR) performance of the InGaAs/InP avalanche photodiode (APD) as a function of the electric gate width and the photon arrival time. The optimal electric gate width was around 1 ns for PNR measurements in our experiment, which provided a PNR capability up to three photons per pulse when the detection efficiency was ~20%. And the dependence of the PNR performance on the arrival time of the photons showed that the photon number could be better resolved if the photons arrived on the rising edge of the electric gate than on the falling edge. In addition, we found that with the increase of the electric gate width, PNR performance got worse. The observation would be helpful for improving the PNR performance of the InGaAs/InP APD in the gated mode. PMID:21221161

Jian, Yi; Wu, E; Chen, Xiuliang; Wu, Guang; Zeng, Heping

2011-01-01

209

Electrical breakdown gas detector featuring carbon nanotube array electrodes.  

PubMed

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

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

2008-01-01

210

InGaAs detector arrays hermetic encapsulation technology  

NASA Astrophysics Data System (ADS)

In this paper, 256×1 and 512×1 element linear InGaAs detector arrays are hermetic packaged. Some processes were studied, including the structure design, thermoelectric cooler (TEC) heat load performance test, TEC vacuum baking, the window sealing, the seam welding of the cover lid and shell, and so on. The results show that the cooling temperature difference of TEC can reach over 55 K at room temperature, and it decreases by about 0.51 K with each additional 50 mW heat load. TEC works well after 500 hours of baking at 120 °C. The leakage rate tests show the assembly is better than 10-5 Pa.cm3/s.

Xu, Qinfei; Liu, Dafu

2010-10-01

211

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

NASA Technical Reports Server (NTRS)

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.

Ando, K. J.

1978-01-01

212

Simultaneous analysis of trans- and cis-isomers of 2-glucosyloxycinnamic acids and coumarin derivatives in Dendrobium thyrsiflorum by high-performance liquid chromatography (HPLC)-photodiode array detection (DAD)-electrospray ionization (ESI)-tandem mass spectrometry (MS)  

Microsoft Academic Search

A novel method has been developed for simultaneous analysis for three pairs of trans- and cis-isomers of 2-glucosyloxycinnamic acids, along with their biogenic metabolites (three coumarin derivatives including scopoletin, scoparone and ayapin) in a Chinese medicinal herb Dendrobium thyrsiflorum by using high-performance liquid chromatography (HPLC)-photodiode array detection (DAD)-electrospray ionization (ESI)-tandem mass spectrometry (MS). The method was carried out by using

Guangnong Zhang; Fang Zhang; Li Yang; Enyuan Zhu; Zhengtao Wang; Luoshan Xu; Zhibi Hu

2006-01-01

213

Identification of the thermal degradation products of g-triiodothyronine sodium (liothyronine sodium) by reversed-phase high-performance liquid chromatography with photodiode-array UV and mass spectrometric detection  

Microsoft Academic Search

The degradation products of the thermally stressed amino acid l-triiodothyronine sodium (liothyronine sodium) were investigated by high-performance liquid chromatography (HPLC) with photodiode-array UV detection and with mass spectrometric detection. Samples stressed at 80°C show a reproducible degradation pattern. Usually, amino acids are degraded to the corresponding aldehyde with one less carbon atom by oxidative deamination (Strecker degradation). In contrast, the

M. Andre; R. Domanig; E. Riemer; H. Moser; A. Groeppelin

1996-01-01

214

Method of fabricating multiwavelength infrared focal plane array detector  

NASA Technical Reports Server (NTRS)

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.

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

1996-01-01

215

Energy spectrum measured by the telescope array surface detector  

NASA Astrophysics Data System (ADS)

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.

Ivanov, Dmitri

2012-05-01

216

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

SciTech Connect

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

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

2010-06-01

217

Determination of nitrofurans in animal feeds by liquid chromatography-UV photodiode array detection and liquid chromatography-ionspray tandem mass spectrometry.  

PubMed

Within the EU, the use of nitrofurans is prohibited in food production animals. For this reason detection of these compounds in feedingstuffs, at whatever limit, constitutes an offence under EU legislation. This detection generally involves the use of analytical methods with limits of quantification lowers than 1 mg kg(-1). These procedures are unsuitable for the detection and confirmation of trace amounts of nitrofurans in feedingstuffs due to contamination. It is well known that very low concentrations of these compounds can be the source of residues of nitrofuran metabolites in meat and other edible products obtained from animals consuming the contaminated feed. The present multi-compound method was capable of measuring very low concentrations of nitrofurantoin (NFT), nitrofurazone (NFZ), furazolidone (FZD) and furaltadone (FTD) in animal feed using nifuroxazide (NXZ) as internal standard. Following ethyl acetate extraction at mild alkaline conditions and purification on NH2 column, the nitrofurans are determined using liquid chromatography with photodiode-array detection (LC-DAD). It was observed a CCalpha ranged from 50 to 100 microg kg(-1). The liquid chromatography-tandem mass spectrometric (LC-MS/MS) procedure was used to confirm the identity of the suspected presence of any of the nitrofuran compounds. PMID:17386735

Barbosa, Jorge; Moura, Sara; Barbosa, Rita; Ramos, Fernando; da Silveira, Maria Irene Noronha

2007-03-14

218

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

PubMed

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

Zgórka, Grazyna

2009-04-01

219

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

PubMed

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

Gao, Yali; Gu, Yanxiang; Wei, Yun

2011-12-28

220

Quantification of trimesic acid in liver, spleen and urine by high-performance liquid chromatography coupled to a photodiode-array detection.  

PubMed

The quantification of trimesic acid, a constitutive organic linker from the biodegradable porous iron(III) trimesate MIL-100(Fe) (MIL stands for Materials from Institut Lavoisier), has been performed in different biological complex media (liver, spleen and urine) using a liquid-liquid extraction procedure. A recovery exceeding 92 wt% was achieved from rat tissues and urine spiked with trimesic acid. After extraction, the determination of the trimesic acid concentration was realised by using a simple and accurate high-performance liquid chromatography (HPLC) method using photodiode-array detection (PDA) and aminosalicylic acid, as internal standard. Linearity of this method was kept from 0.01 to 100mg of trimesic acid per liter of urine and from 0.05 to 5.00 wt% of trimesic acid per tissue weight. The limit of detection of the method was 0.01 ?g per injection. This method was finally applied to analyze and quantify the amount of trimesic acid in rat urine and tissue samples at the different stages of degradation of MIL-100(Fe). PMID:21727049

Baati, Tarek; Horcajada, Patricia; Gref, Ruxandra; Couvreur, Patrick; Serre, Christian

2011-08-01

221

Quantification of tetramethyl-terephthalic acid in rat liver, spleen and urine matrices by liquid-liquid phase extraction and HPLC-photodiode array detection.  

PubMed

Tetramethyl-terephthalate (TMT) is the constitutive linker of the flexible porous iron(III) carboxylate Metal Organic Framework (MOF) MIL-88B_4CH? based drug nanocarrier (MIL stands for Material from Institut Lavoisier). A method for the determination of the concentration of tetramethyl-terephthalic acid has been developed in different biological rat matrices (liver, spleen and urine) using a liquid-liquid phase extraction and high-performance liquid chromatography (HPLC) coupled to photodiode array detection with 4-aminosalicylic acid as internal standard. The extraction conditions of TMT have been varied from urine to tissue depending on the complexity of the biological matrices. The chromatographic separation was performed with a gradient elution. In all matrices, the limits of detection and quantification of TMT was 0.01 and 0.05 ?g ml?¹, respectively. The recovery of the TMT reached 86, 89 and 97% for urine, spleen and liver tissues, respectively. The linearity of the calibration curves in urine and tissues was satisfactory in all cases as evidenced by correlation coefficients >0.990. The within-day and between-day precisions were <15% (n=6) and the accuracy ranged in all cases between 86 and 103%. This method has finally allowed the quantification of TMT in rat urine and in tissue samples of rats administered intravenously with iron(III) tetramethyltherepthalate MIL-88B_4CH? nanoparticles. PMID:22608098

Baati, Tarek; Horcajada, Patricia; David, Olivier; Gref, Ruxandra; Couvreur, Patrick; Serre, Christian

2012-01-01

222

Advanced ultra-performance liquid chromatography-photodiode array-quadrupole time-of-flight mass spectrometric methods for simultaneous screening and quantification of triterpenoids in Poria cocos.  

PubMed

A sensitive, precise and accurate method was developed to screen and quantify triterpenoids based on ultra-performance liquid chromatography-photodiode array-quadrupole time-of-flight mass spectrometry (UPLC-PDA-QTOF-MS). An exact neutral loss scan of 62.0004 Da (CH2O3) was used to selectively detect triterpenoids in Poria cocos, followed by a survey scan for exact masses of precursor and fragment ions of these triterpenoids. The developed method was applied to quantify seven major triterpenoids in 40 P. cocos samples of different origins within 18 min, and a total of 31 triterpenoids were unequivocally or tentatively identified. Principal component analysis of these samples showed a clear separation of three groups, and ten triterpenoids play key roles in differentiating these samples were obtained from the OPLS-DA variable influence on projection (VIP) plot and then unequivocally or tentatively identified. The developed method can be applied for rapid bitterness evaluation, quality control and authenticity establishment of P. cocos. PMID:24444932

Xia, Bing; Zhou, Yan; Tan, Hong Sheng; Ding, Li Sheng; Xu, Hong Xi

2014-01-01

223

Determination of 40 synthetic food colors in drinks and candies by high-performance liquid chromatography using a short column with photodiode array detection.  

PubMed

Forty synthetic food colors were determined in drinks and candies by reversed-phase high-performance liquid chromatography with photodiode array detection. The following food colors were analyzed within 19 min using a short analytical column (50 mm x 4.6 mm i.d., 1.8 microm) at 50 degrees C with gradient elution: Ponceau 6R, Tartrazine, Fast yellow AB, Amaranth, Indigotine, Naphthol yellow S, Chrysoine, Ponceau 4R, Sunset yellow FCF, Red 10B, Orange G, Acid violet 7, Brilliant black PN, Allura red AC, Yellow 2G, Red 2G, Uranine, Fast red E, Green S, Ponceau 2R, Azorubine, Orange I, Quinoline yellow, Martius yellow, Ponceau SX, Ponceau 3R, Fast green FCF, Eosine, Brilliant blue FCF, Orange II, Orange RN, Acid blue 1, Erythrosine, Amido black 10B, Acid red 52, Patent blue V, Acid green 9, Phloxine B, Benzyl violet 4B, and Rose bengal. The recoveries of these compounds added to soft drinks and candies at 5 microg/g ranged from 76.6 to 115.0%, and relative standard deviations (R.S.D.s) were within 6.0%. The limits of detection and the limits of quantitation were 0.03 and 0.1 microg/g, respectively. PMID:18371797

Yoshioka, N; Ichihashi, K

2008-02-15

224

HgCdTe e-APD detector arrays with single photon sensitivity for space lidar applications  

NASA Astrophysics Data System (ADS)

A multi-element HgCdTe electron initiated avalanche photodiode (e-APD) array has been developed for space lidar. The detector array was fabricated with 4.3?m cutoff HgCdTe with a spectral response from 0.4 to 4.3 ?m. We have demonstrated a 4x4 e-APD array with 80 ?m square elements followed by a custom cryogenic CMOS read-out integrated circuit (ROIC). The device operates at 77K inside a small closed-cycle cooler-Dewar with the support electronics integrated in a field programmable gate array. Measurements showed a unity gain quantum efficiency of about 90% at 1.5-1.6 ?m wavelength. The bulk dark current of the HgCdTe e-APD at 77K was less than 50,000 input referred electrons/s at 12 V APD bias where the APD gain was 620 and the measured noise equivalent power (NEP) was 0.4 fW/Hz1/2. The electrical bandwidth of the device was about 6 MHz, mostly limited by the ROIC, but sufficient for the lidar application. Although the devices were designed for low bandwidth pulse detections, the high gain and low dark current enabled them to be used for single photon detections. Because the APD was biased below the break-down voltage, the output is linear to the input signal and there were no nonlinear effect such as dead-time and afterpulsing, and no need for gated operation. A new series of HgCdTe e-APDs have also been developed with a much wider bandwidth ROIC and higher APD gain, which is expected to give a much better performance in single photon detections.

Sun, Xiaoli; Abshire, James B.; Beck, Jeffrey D.

2014-05-01

225

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

NASA Astrophysics Data System (ADS)

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.

Wikner, David; Grossman, Erich

2009-05-01

226

Mechanics of cadmium telluride-zinc telluride nucleation on (112) Si for mercury cadmium telluride infrared photo-diode arrays  

Microsoft Academic Search

Epitaxy of CdTe\\/ZnTe on the extremely large lattice mismatched Si leads to high density of dislocations, multi-domain facets, rough surface morphology, and often Cd-terminated surface polarity. These problems, related to the mode of nucleation and growth, limit its application to manufacture improved HgCdTe based large area infrared focal plane arrays. Thermo-kinetics of ZnTe nucleation on \\

Nibir Kumar Dhar

1997-01-01

227

Measuring dose distributions for enhanced dynamic wedges using a multichamber detector array.  

PubMed

This paper investigates measuring dose distributions for enhanced dynamic wedges (EDWs) using a commercial multichamber detector array. The technical aspects of using the chamber array, including chamber calibration, selection of measurement parameters, and use of the reference chamber, have been fully investigated. The measurement results from the chamber array were also confirmed by those from the single chamber and radiographic film measurements. The results reported here showed that proper operation of the chamber array is essential to measure dose accurately for the EDW fields; the chamber detector array can be used more efficiently than a single chamber without compromising the dose measurement accuracy. PMID:9304581

Liu, H H; Lief, E P; McCullough, E C

1997-09-01

228

Evaluation of chamber response function influence on IMRT verification using 2D commercial detector arrays  

Microsoft Academic Search

This work is devoted to studying the influence of chamber response functions on the standard IMRT verification for the different detector technologies available on commercial devices. We have tested three of the most used 2D detector arrays for radiotherapy dosimetry verification, based on air-ionization chambers and diode detectors. The response function has been carefully simulated using the Monte Carlo method

A Gago-Arias; L Brualla-González; D M González-Castaño; F Gómez; M Sánchez García; V Luna Vega; J Mosquera Sueiro; J Pardo-Montero

2012-01-01

229

Driving spectral resolution to the noise limit in semiconductor gamma detector arrays  

Microsoft Academic Search

Shape time adjustment of a standard detector circuit improves the resolution of a single pixel of a detector array to the noise limit. Steady flow of gamma generated charge, in a detector bulk, induces fast signal build-up, as the charge arrives near to a single pixel. The build-up period is shorter than the electron transition time from contact to contact.

Uri Lachish

2000-01-01

230

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

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

231

Analytical model of single-X-ray photon counting pixel-array detectors  

NASA Astrophysics Data System (ADS)

Single-X-ray-photon counting pixel array detectors are now widely used on synchrotron beamlines for X-ray diffraction and imaging experiments. Efforts have been carried out in the recent years to extend X-ray detector system analysis to include charge-sharing effects and characteristic X-ray re-absorption on image quality parameters such as MTF, NPS and DQE. These efforts led to the formulation of an analytical model of single-X-ray-photon counting pixel array detectors which is presented in this contribution to the IWORID-2013 conference. This model links together imaging and spectroscopic performance of pixel array detectors. It provides a framework for optimising the design of single-energy threshold, multiple-energy thresholds and energy-sensitive pixel array detectors. This analytical model is applied to typical silicon- and CdTe-based pixel sensor geometries associated to single-X-ray processing read-out electronics.

Marchal, J.; McGrath, J.; Medjoubi, K.

2014-03-01

232

Leakage mechanisms and potential performance of molecular-beam epitaxially grown GaInAsSb 2.4 {mu}m photodiode detectors  

SciTech Connect

We report on the growth, processing, and characterization of uncoated, unpassivated GaInAsSb detector mesa photodiodes with a cutoff wavelength of 2.4 {mu}m. We find peak room temperature specific detectivity value of 6x10{sup 10} cm Hz{sup 1/2}/W and maximum zero-bias resistivity of 25 {omega} cm{sup 2}. The zero-bias resistivities of mesas with areas ranging from 50{sup 2} {mu}m{sup 2} to 1 mm{sup 2} were found to be limited by generation-recombination currents at mesa sidewalls. At low temperatures, devices were limited by Ohmic leakage, which is likely due to the formation of oxides on the sidewalls. After 6 months of aging, Ohmic leakage becomes the limiting factor at room temperature as well. Based on experimentally obtained material parameters in this and other studies, an upper limit D* and R{sub 0}A were estimated for GaInAsSb materials and compared to those HgCdTe and InGaAs.

Prineas, J. P.; Yager, J.; Seyedmohamadi, S. [Department of Physics and Astronomy, Optical Sciences and Technology Center, University of Iowa, Iowa City, Iowa 52242 (United States); Olesberg, J. T. [Department of Chemistry, Optical Sciences and Technology Center, University of Iowa, Iowa City, Iowa 52242 (United States)

2008-05-15

233

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

NASA Technical Reports Server (NTRS)

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.

Timothy, J. G.

1984-01-01

234

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

NASA Astrophysics Data System (ADS)

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.

Dereniak, Eustace L.; Sampson, Robert E.

1990-09-01

235

The Design and Performance of the 384: Element Submillimeter Detector Array for SHARC II  

NASA Technical Reports Server (NTRS)

We report on the performance of the SHARC II detector, a 12 x 32 array of ion implanted Si pop-up bolometers. This 384 element detector array was built as a prototype for the High Angular Resolution Widefield Camera (HAWC) for the Stratospheric Observatory for Infrared Astronomy (SOFIA). We will discuss the design process, the characterization of the detectors, and the performance of the array in the SHARC II instrument. SHARC II is now a facility instrument on the Caltech Submillimeter Observatory, providing background-limited imaging at 350 and 450 microns.

Moseley, Samuel H.; Allen, Christine; Benford, Dominic; Silverberg, Robert; Staguhn, Johannes; Dowell, Darren; Phillips, Tom

2003-01-01

236

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

PubMed

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

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

2012-01-01

237

Three-dimensional numerical simulation of planar P+n heterojunction In0.53Ga0.47As photodiodes in dense arrays part I: dark current dependence on device geometry  

NASA Astrophysics Data System (ADS)

Low light level imaging applications requiring high detectivity demand photon shot noise limited performance at temperatures near 300K. Analytical models, however, have provided limited insight on underlying mechanisms limiting performance in conventional planar double heterointerface In0.53Ga0.47As on InP P+n photodiodes for imaging the visible and short wave infrared. Quantitative modeling provides tools to investigate performance sensitivities and their underlying mechanisms. In this work we use three-dimensional numerical simulation to investigate intrinsically limited diffusion and Shockley-Read-Hall generation recombination dark currents for a planar P+n photodiode situated in a 3×3 mini array. We assess the influence of geometry by varying pitch, junction location, and photodiode size. Modeling shows that SRH generation currents, not including surface effects, vary with both junction perimeter and area, and that the perimeter component dominates small radius junctions. By varying the axial junction placement we show that widegap junctions result in bias-dependent quantum efficiencies that require higher reverse bias, and result in higher dark currents, than shallow homojunctions at comparable efficiencies. Finally, numerical simulation explains lateral diffusion current suppression in dense arrays in terms of suppressed minority carrier density gradients. The analysis demonstrates that the boundary condition applicable to dense arrays requires no lateral diffusion current at symmetry planes bisecting segments connecting uniformly reverse biased nearest neighbor diodes. Following Grimbergen, this leads to radial geometry curves describing dark intrinsic diffusion reductions with pitch. The quantitative modeling provides insight explaining the observation that the ideal diode equation correctly estimates dense array dark diffusion currents.

Wichman, Adam R.; DeWames, Roger E.; Bellotti, Enrico

2014-06-01

238

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

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

239

Simultaneous determination of pseudoephedrine hydrochloride, chlorpheniramine maleate, and dextromethorphan hydrobromide by second-derivative photodiode array spectroscopy.  

PubMed

The simultaneous determination of the active ingredients in multicomponent pharmaceutical products normally requires the use of a separation technique, such as HPLC or GC, followed by quantitation. Presented here is a rapid, validated, analytical method that does not require prior separation for the simultaneous determination of three drugs, pseudoephedrine hydrochloride, chlorpheniramine maleate, and dextromethorphan hydrobromide, in a tablet formulation. A diode array spectrophotometer, capable of multicomponent analysis, was used for the quantitation. The utility of this method was demonstrated in two ways: the analysis of a chewable pediatric tablet (formulation CP) containing 7.5 mg of pseudoephedrine hydrochloride, 0.5 mg of chlorpheniramine maleate, and 2.5 mg of dextromethorphan hydrobromide, and the dissolution analysis of a hydroxypropyl methylcellulose-based sustained-release tablet (formulation SR) containing 120 mg of pseudoephedrine hydrochloride, 8 mg of chlorpheniramine maleate, and 60 mg of dextromethorphan hydrobromide. The sensitivity of this assay is 7.5 micrograms/mL for pseudoephedrine hydrochloride, 1.0 micrograms/mL for chlorpheniramine maleate, and 5.0 micrograms/mL for dextromethorphan hydrobromide, using the second-derivative spectra of the absorbance with respect to wavelength. Determinations were made in 0.1 M sodium acetate buffer at pH 5.0 using a 1-cm quartz cell. Absorbance spectra, and their first and second derivatives, from 240 to 300 nm were used for the determination. The results obtained by this method compared favorably with the results obtained by a validated HPLC method. PMID:3210162

Murtha, J L; Julian, T N; Radebaugh, G W

1988-08-01

240

Evaluation of selected detector arrays for space applications  

NASA Technical Reports Server (NTRS)

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.

Lowrance, J. L.

1986-01-01

241

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

PubMed

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

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

2010-01-01

242

Method of fabricating a PbS-PbSe IR detector array  

NASA Technical Reports Server (NTRS)

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.

Barrett, John R. (Inventor)

1987-01-01

243

Test structures and performance analysis for uncooled resistance bolometer detector arrays  

NASA Astrophysics Data System (ADS)

The performance of uncooled infrared focal plane detector arrays depends on optimization of critical parameters which are determined by geometrical design and the electrical, optical and thermophysical properties of the detector materials. It is desirable to monitor these parameters during array preparation using test cells which are independent of the main array and which can subsequently be used to provide data for performance analysis. This paper describes the use of test structures which function as process control modules and monitor cells for material parameters, from which array operability and performance can be assessed. The focal plane detector arrays described in the paper were designed by Electro-optic Sensor Design and manufactured by the Defence Science and Technology Organization, Australia, in collaboration with the Defence Research Establishment, Sweden.

Liddiard, Kevin C.; Reinhold, Olaf; Ringh, Ulf; Jansson, Christer

1998-07-01

244

Multiplexed readout of MMC detector arrays using non-hysteretic rf-SQUIDs  

E-print Network

Metallic magnetic calorimeters (MMCs) are widely used for various experiments in fields ranging from atomic and nuclear physics to x-ray spectroscopy, laboratory astrophysics or material science. Whereas in previous experiments single pixel detectors or small arrays have been used, for future applications large arrays are needed. Therefore, suitable multiplexing techniques for MMC arrays are currently under development. A promising approach for the readout of large arrays is the microwave SQUID multiplexer that operates in the frequency domain and that employs non-hysteretic rf-SQUIDs to transduce the detector signals into a frequency shift of high $Q$ resonators which can be monitored by using standard microwave measurement techniques. In this paper we discuss the design and the expected performance of a recently developed and fabricated 64 pixel detector array with integrated microwave SQUID multiplexer. First experimental data were obtained characterizing dc-SQUIDs with virtually identical washer design.

Kempf, S; Gastaldo, L; Fleischmann, A; Enss, C

2013-01-01

245

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

Microsoft Academic Search

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

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

246

Three-Dimensional Position Sensitive CdZnTe Detector Array for PNNL  

Microsoft Academic Search

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 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

Feng Zhang; Zhong He; Carolyn E. Seifert

2006-01-01

247

Arrays of SiO2 substrate-free micromechanical uncooled infrared and terahertz detectors  

NASA Astrophysics Data System (ADS)

We describe the design, fabrication, and characterization of arrays of uncooled infrared and terahertz micromechanical detectors that utilize SiO2 as a main structural material. Materials with highly dissimilar coefficients of thermal expansion, namely, Al and SiO2, were used to form folded bimaterial regions. This approach improved the detector sensitivity by 12 times compared to SiNx-based detectors of similar shape and size. Two types of structural SiO2 layers were investigated: thermally grown and plasma-enhanced chemical-vapor-deposited SiO2. Fabrication of the detector arrays relied on a straightforward process flow that involved three photolithography steps and no wet etching. The noise equivalent temperature difference intrinsic to the detectors fabricated during this work can reach 3.8 mK when excluding any contribution from the optical readout used to interrogate the arrays.

Grbovic, D.; Lavrik, N. V.; Rajic, S.; Datskos, P. G.

2008-09-01

248

Characteristics of stereo images from detectors in focal plane array.  

PubMed

The equivalent ray geometry of two horizontally aligned detectors at the focal plane of the main antenna in a millimeter wave imaging system is analyzed to reveal the reason why the images from the detectors are fused as an image with a depth sense. Scanning the main antenna in both horizontal and vertical directions makes each detector perform as a camera, and the two detectors can work like a stereo camera in the millimeter wave range. However, the stereo camera geometry is different from that of the stereo camera used in the visual spectral range because the detectors' viewing directions are diverging to each other and they are a certain distance apart. The depth sense is mainly induced by the distance between detectors. The images obtained from the detectors in the millimeter imaging system are perceived with a good depth sense. The disparities responsible for the depth sense are identified in the images. PMID:21734748

Son, Jung-Young; Yeom, Seokwon; Chun, Joo-Hwan; Guschin, Vladmir P; Lee, Dong-Su

2011-07-01

249

Silicon technology in ion detection--a high resolution detector array  

Microsoft Academic Search

A new ion detecto array integrated on a silicon chip with a high spatial resolution has been designed at Aberystwyth. Integrated circuits are mounted on a ceramic substrate beneath a microchannel plate electron multiplier giving a small, light, low power, very low noise module. An array containing 384 detectors with a spatial resolution of 25 microns has been fully tested

K. Birkinshaw; D. P. Langstaff

1994-01-01

250

A biologically inspired compound-eye detector array part II: Statistical performance analysis  

Microsoft Academic Search

This is the second part of our paper. In this paper, we propose, model, and analyze the performance of a detector array for localizing far-field particle-emitting sources, which is inspired by but generalizes the compound eye of insects. The array consists of multiple eyelets, each having a conical module with a lens on its top and an inner subarray containing

Zhi Liu; Arye Nehorai; Eytan Paldi

2009-01-01

251

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

E-print Network

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

Gardel, Margaret

252

Development of a Versatile Array of Neutron Detectors at Low Energy  

NASA Astrophysics Data System (ADS)

The Versatile Array of Neutron Detectors at Low Energy (VANDLE) is a new array of plastic scintillator bars under development for measurements at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The array is highly modular allowing the configuration of the individual elements to be optimized for particular experimental requirements, such as (d,n) and beta-delayed neutron-decay measurements with neutron-rich rare isotope beams.

Matei, C.; Bardayan, D. W.; Blackmon, J. C.; Cizewski, J. A.; Grzywacz, R. K.; Liddick, S. N.; Padgett, S. W.; Peters, W. A.; Sarazin, F.

2009-03-01

253

Integrated filter and detector array for spectral imaging  

NASA Technical Reports Server (NTRS)

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.

Labaw, Clayton C. (inventor)

1992-01-01

254

Simulation of near-infrared photodiode detectors based on ?-FeSi2/4H-SiC heterojunctions  

NASA Astrophysics Data System (ADS)

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.

Pu, Hong-Bin; He, Xin; Quan, Ru-Dai; Cao, Lin; Chen, Zhi-Ming

2013-03-01

255

A position sensitive detector system consisting of an array of mini-proportional counters  

NASA Astrophysics Data System (ADS)

A new position sensitive detector system has been developed for the Hard X-ray Imaging Spectrometer launched aboard the NASA Solar Maximum Mission. The instrument operates in the energy range 3.5 - 30 keV. The Xe-gas filled detector system consists of a photon absorption compartment and an array of 900 mini-proportional counters. The detector lay-out and the system performance are described.

van Beek, H. F.; Boelee, A.; van der Laan, J. J. M.; Mels, W. A.

1984-02-01

256

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

Microsoft Academic Search

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

J. Abraham; P. Abreu; M. Aglietta; E. J. Ahn; D. Allard; I. Allekotte; J. Allen; J. Alvarez-Muñiz; M. Ambrosio; L. Anchordoqui; S. Andringa; T. Anticic; A. Anzalone; C. Aramo; E. Arganda; K. Arisaka; F. Arqueros; H. Asorey; P. Assis; J. Aublin; G. Avila; T. Bäcker; D. Badagnani; M. Balzer; K. B. Barber; A. F. Barbosa; S. L. C. Barroso; B. Baughman; P. Bauleo; J. J. Beatty; B. R. Becker; K. H. Becker; A. Bellétoile; J. A. Bellido; S. Benzvi; C. Berat; T. Bergmann; X. Bertou; P. L. Biermann; P. Billoir; O. Blanch-Bigas; F. Blanco; M. Blanco; H. Blümer; M. Bohácová; D. Boncioli; C. Bonifazi; R. Bonino; N. Borodai; J. Brack; P. Brogueira; W. C. Brown; R. Bruijn; P. Buchholz; A. Bueno; R. E. Burton; N. G. Busca; K. S. Caballero-Mora; L. Caramete; R. Caruso; A. Castellina; O. Catalano; G. Cataldi; L. Cazon; R. Cester; J. Chauvin; A. Chiavassa; J. A. Chinellato; A. Chou; J. Chudoba; R. W. Clay; E. Colombo; M. R. Coluccia; R. Conceição; F. Contreras; H. Cook; M. J. Cooper; J. Coppens; A. Cordier; U. Cotti; S. Coutu; C. E. Covault; A. Creusot; A. Criss; J. Cronin; A. Curutiu; S. Dagoret-Campagne; R. Dallier; K. Daumiller; B. R. Dawson; R. M. de Almeida; C. de Donato; S. J. de Jong; G. De La Vega; I. De Mitri; V. de Souza; K. D. de Vries; G. Decerprit; L. del Peral; O. Deligny; A. Della Selva; C. Delle Fratte; H. Dembinski; C. Di Giulio; J. C. Diaz; M. L. Díaz Castro; P. N. Diep; C. Dobrigkeit; J. C. D’Olivo; P. N. Dong; A. Dorofeev; J. C. dos Anjos; M. T. Dova; D. D’Urso; I. Dutan; M. A. DuVernois; J. Ebr; R. Engel; M. Erdmann; C. O. Escobar; A. Etchegoyen; P. Facal San Luis; H. Falcke; G. Farrar; A. C. Fauth; N. Fazzini; A. Ferrero; B. Fick; A. Filevich; A. Filipcic; I. Fleck; S. Fliescher; C. E. Fracchiolla; E. D. Fraenkel; U. Fröhlich; W. Fulgione; R. F. Gamarra; S. Gambetta; B. García; D. García Gámez; D. Garcia-Pinto; X. Garrido; G. Gelmini; H. Gemmeke; P. L. Ghia; U. Giaccari; M. Giller; H. Glass; L. M. Goggin; M. S. Gold; G. Golup; F. Gomez Albarracin; M. Gómez Berisso; P. Gonçalves; D. Gonzalez; J. G. Gonzalez; D. Góra; A. Gorgi; P. Gouffon; S. R. Gozzini; E. Grashorn; S. Grebe; M. Grigat; A. F. Grillo; Y. Guardincerri; F. Guarino; G. P. Guedes; J. D. Hague; V. Halenka; P. Hansen; D. Harari; S. Harmsma; J. L. Harton; A. Haungs; T. Hebbeker; D. Heck; A. E. Herve; C. Hojvat; V. C. Holmes; P. Homola; J. R. Hörandel; A. Horneffer; M. Hrabovský; T. Huege; M. Hussain; M. Iarlori; A. Insolia; F. Ionita; A. Italiano; S. Jiraskova; K. Kadija; M. Kaducak; K. H. Kampert; T. Karova; P. Kasper; B. Kégl; B. Keilhauer; A. Keivani; J. Kelley; E. Kemp; R. M. Kieckhafer; H. O. Klages; M. Kleifges; J. Kleinfeller; R. Knapik; J. Knapp; D.-H. Koang; A. Krieger; O. Krömer; D. Kruppke-Hansen; F. Kuehn; D. Kuempel; K. Kulbartz; N. Kunka; A. Kusenko; G. La Rosa; C. Lachaud; B. L. Lago; P. Lautridou; M. S. A. B. Leão; D. Lebrun; P. Lebrun; J. Lee; M. A. Leigui de Oliveira; A. Lemiere; A. Letessier-Selvon; I. Lhenry-Yvon; R. López; A. Lopez Agüera; K. Louedec; J. Lozano Bahilo; A. Lucero; M. Ludwig; H. Lyberis; M. C. Maccarone; C. Macolino; S. Maldera; D. Mandat; P. Mantsch; A. G. Mariazzi; V. Marin; I. C. Maris; H. R. Marquez Falcon; G. Marsella; D. Martello; O. Martínez Bravo; H. J. Mathes; J. Matthews; G. Matthiae; D. Maurizio; P. O. Mazur; M. McEwen; G. Medina-Tanco; M. Melissas; D. Melo; E. Menichetti; A. Menshikov; C. Meurer; S. Micanovic; M. I. Micheletti; W. Miller; L. Miramonti; S. Mollerach; M. Monasor; D. Monnier Ragaigne; F. Montanet; B. Morales; C. Morello; E. Moreno; J. C. Moreno; C. Morris; M. Mostafá; S. Mueller; M. A. Muller; R. Mussa; G. Navarra; J. L. Navarro; S. Navas; P. Necesal; L. Nellen; P. T. Nhung; N. Nierstenhoefer; D. Nitz; D. Nosek; L. Nozka; M. Nyklicek; J. Oehlschläger; A. Olinto; P. Oliva; V. M. Olmos-Gilbaja; M. Ortiz; N. Pacheco; D. Pakk Selmi-Dei; M. Palatka; J. Pallotta; N. Palmieri; G. Parente; E. Parizot; S. Parlati; A. Parra; J. Parrisius; R. D. Parsons; S. Pastor; T. Paul; V. Pavlidou; K. Payet; M. Pech; R. Pelayo; I. M. Pepe; L. Perrone; R. Pesce; E. Petermann; S. Petrera; P. Petrinca; A. Petrolini; Y. Petrov; J. Petrovic; C. Pfendner; R. Piegaia; T. Pierog; M. Pimenta; V. Pirronello; M. Platino; V. H. Ponce; M. Pontz; P. Privitera; M. Prouza; E. J. Quel; J. Rautenberg; O. Ravel; D. Ravignani; A. Redondo; B. Revenu; F. A. S. Rezende; J. Ridky; S. Riggi; M. Risse; P. Ristori; C. Rivière; V. Rizi; C. Robledo; G. Rodriguez; J. Rodriguez Martino; J. Rodriguez Rojo; I. Rodriguez-Cabo; M. D. Rodríguez-Frías; G. Ros; J. Rosado; T. Rossler; M. Roth; B. Rouillé-d’Orfeuil; E. Roulet; A. C. Rovero; F. Salamida; H. Salazar; G. Salina; F. Sánchez; M. Santander; C. E. Santo; E. Santo; E. M. Santos; F. Sarazin; S. Sarkar; R. Sato; N. Scharf; V. Scherini; H. Schieler; P. Schiffer; A. Schmidt; F. Schmidt

2010-01-01

257

Driving spectral resolution to the noise limit in semiconductor gamma detector arrays  

Microsoft Academic Search

Shape-time adjustment of a standard detector circuit improves the resolution of a single pixel of a detector array to the noise limit. The steady flow of gamma generated charge, in a detector bulk, induces fast signal build-up, as the charge arrives near a single pixel. The build-up period is shorter than the electron transition time from contact to contact. The

Uri Lachish

2001-01-01

258

Modulation transfer function of a triangular pixel array detector.  

PubMed

The modulation transfer function (MTF) is the main parameter that is used to evaluate image quality in electro-optical systems. Detector sampling MTF in most electro-optical systems determines the cutoff frequency of the system. The MTF of the detector depends on its pixel shape. In this work, we calculated the MTF of a detector with an equilateral triangular pixel shape. Some new results were found in deriving the MTF for the equilateral triangular pixel shape. PMID:25121458

Karimzadeh, Ayatollah

2014-07-01

259

The utility of available low quantum efficiency detector arrays for tactical imaging  

NASA Astrophysics Data System (ADS)

A mosaic detector array which uses a charge coupled array to integrate and multiplex signals is significantly limited by charge saturation. Detection of warm targets by infrared sensing through the atmosphere tends to be limited more by clutter than by random fluctuations. For missions at television frame rates the important attributes of the detector array are good spatial resolution and uniformity of response. Responsive quantum efficiency is relatively unimportant. Operation at 3 to 4.2 microns offers advantages of resolution and larger rate of change of radiant signal with temperature.

Jamieson, J. A.

1980-01-01

260

Waveguide biosensor with integrated detector array for tuberculosis testing  

NASA Astrophysics Data System (ADS)

A label-free immunoassay using a local evanescent array coupled (LEAC) biosensor is reported. Complementary metal oxide semiconductor chips with integrated photoconductor arrays are used to detect an antibody to a M. tuberculosis protein antigen, HspX. The metrology limits of the LEAC sensor using dc and ac measurement systems correspond to average film thicknesses of 28 and 14 pm, respectively. Limits of detection are 87 and 108 pm, respectively, for mouse immunoglobulin G antibody patterning and antigen detection.

Yan, Rongjin; Lynn, N. Scott; Kingry, Luke C.; Yi, Zhangjing; Slayden, Richard A.; Dandy, David S.; Lear, Kevin L.

2011-01-01

261

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

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

262

Semiconductor detectors and focal plane arrays for far-infrared imaging  

NASA Astrophysics Data System (ADS)

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.

Rogalski, A.

2013-12-01

263

National Array of Neutron Detectors (NAND): A versatile tool for nuclear reaction studies  

NASA Astrophysics Data System (ADS)

The first phase of the National Array of Neutron Detectors (NAND) consisting of 26 neutron detectors has been commissioned at the Inter University Accelerator Centre (IUAC), New Delhi. The motivation behind setting up of such a detector system is the need for more accurate and efficient study of reaction mechanisms in the projectile energy range of 5-8 MeV/n using heavy ion beams from a 15 UD Pelletron and an upgraded LINAC booster facility at IUAC. The above detector array can be used for inclusive as well as exclusive measurements of reaction products of which at least one product is a neutron. While inclusive measurements can be made using only the neutron detectors along with the time of flight technique and a pulsed beam, exclusive measurements can be performed by detecting neutrons in coincidence with charged particles and/or fission fragments detected with ancillary detectors. The array can also be used for neutron tagged gamma-ray spectroscopy in (HI, xn) reactions by detecting gamma-rays in coincidence with the neutrons in a compact geometrical configuration. The various features and the performance of the different aspects of the array are described in the present paper.

Golda, K. S.; Jhingan, A.; Sugathan, P.; Singh, Hardev; Singh, R. P.; Behera, B. R.; Mandal, S.; Kothari, A.; Gupta, Arti; Zacharias, J.; Archunan, M.; Barua, P.; Venkataramanan, S.; Bhowmik, R. K.; Govil, I. M.; Datta, S. K.; Chatterjee, M. B.

2014-11-01

264

Optochemical sensor based on screenprinted fluorescent sensorspots surrounded by organic photodiodes for multianalyte detection  

NASA Astrophysics Data System (ADS)

A compact, integrated photoluminescence based oxygen sensor, utilizing an organic light emitting device (OLED) as the light source and an organic photodiode (OPD) as the detection unit, is described. The detection system of the sensor array consists of an array of circular screen-printed fluorescent sensor spots surrounded by organic photodiodes as integrated fluorescence detectors. The OPD originates from the well-known Tang photodiode, consisting of a stacked layer of copper phthalocyanine (CuPc, p-type material) and perylene tetracarboxylic bisbenzimidazole (PTCBi, n-type material). An additional layer of tris-8-hydroxyquinolinatoaluminium (Alq3, n-type material) was inserted between the PTCBi layer and cathode. An ORMOCERR layer was used as encapsulation layer. For excitation an organic light emitting diode is used. The sensor spot and the detector are processed on the same flexible substrate. This approach not only simplifies the detection system by minimizing the numbers of required optical components - no optical filters have to be used for separating the excitation light and the luminescent emission-, but also has a large potential for low-cost sensor applications. The feasibility of the concept is demonstrated by an integrated oxygen sensor, indicating good performance. Sensor schemes for other chemical parameters are proposed.

Kraker, E.; Lamprecht, B.; Haase, A.; Jakopic, G.; Abel, T.; Konrad, C.; Köstler, S.; Tscherner, M.; Stadlober, B.; Mayr, T.

2010-08-01

265

A cooled avalanche photodiode with high photon detection probability  

NASA Technical Reports Server (NTRS)

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.

Robinson, D. L.; Metscher, B. D.

1986-01-01

266

Real-time human identification using a pyroelectric infrared detector array and hidden Markov models  

NASA Astrophysics Data System (ADS)

This paper proposes a real-time human identification system using a pyroelectric infrared (PIR) detector array and hidden Markov models (HMMs). A PIR detector array with masked Fresnel lens arrays is used to generate digital sequential data that can represent a human motion feature. HMMs are trained to statistically model the motion features of individuals through an expectation-maximization (EM) learning process. Human subjects are recognized by evaluating a set of new feature data against the trained HMMs using the maximum-likelihood (ML) criterion. We have developed a prototype system to verify the proposed method. Sensor modules with different numbers of detectors and different sampling masks were tested to maximize the identification capability of the sensor system.

Fang, Jian-Shuen; Hao, Qi; Brady, David J.; Guenther, Bob D.; Hsu, Ken Y.

2006-07-01

267

Application and Design of Satellite Infrared Spectral Imaging Radiometers with Uncooled Microbolometer Array Detectors  

NASA Technical Reports Server (NTRS)

Uncooled infrared microbolometer array detectors have application for space borne spectral imaging radiometer of several types to lower size, power and cost and provide improved performance. Other advantages of eliminating cooling requirement are simplified systems, simplified satellite integration and improved reliability. A prototype microbolometer instrument for cloud observations was flown on the STS-85 space shuttle mission. Extensive data were acquired at_km resolution at four thermal infrared wavelength bands. From the 320x280 detector array both spectral and angular information can be used to advantage in cloud retrievals and has been demonstrated. An engineering model Compact Visible and Infrared Imaging Radiometer (COVIR) for small satellite missions has been developed. Application of advanced microbolometer array detectors for three axis stabilized GOES thermal imagers has been studied.

Spinhirne, James; Lancaster, Regie; Maschhoff, Kevin; Starr, David OC (Technical Monitor)

2001-01-01

268

Description of the Role of Shot Noise in Spectroscopic Absorption and Emission Measurements with Photodiode and Photomultiplier Tube Detectors: Information for an Instrumental Analysis Course  

ERIC Educational Resources Information Center

A description of shot noise and the role it plays in absorption and emission measurements using photodiode and photomultiplier tube detection systems is presented. This description includes derivations of useful forms of the shot noise equation based on Poisson counting statistics. This approach can deepen student understanding of a fundamental…

McClain, Robert L.; Wright, John C.

2014-01-01

269

Integrating 128 element InSb array - Recent results. [for spaceborne infrared spectrometers  

NASA Technical Reports Server (NTRS)

There has been a continuing evolution toward larger arrays of infrared detectors, and the technology base derived from the Galileo Near Infrared Mapping Spectrometer (NIMS) has been expanded to linear arrays including from 128 to 512 elements. This advance is based on the commercial availability of high-quality InSb photodiodes and 128/256 element FET switch MUX's (multiplexing elements). The present investigation is concerned with an experimental 128-element linear imager using InSb detectors and silicon MUX for readout. Attention is given to detector array electrical characteristics, the detector readout architecture, noise, and special effects.

Bailey, G.

1982-01-01

270

Liquid-helium scintillation detection with germanium photodiodes  

SciTech Connect

Special high-purity germanium photodiodes have been developed for the direct detection of vacuum ultraviolet scintillations in liquid helium. The photodiodes are immersed in the liquid helium, and scintillations are detected through one of the bare sides of the photodiodes. Test results with scintillation photons produced by 5.3-MeV ..cap alpha.. particles are presented. The use of these photodiodes as liquid-helium scintillation detectors may offer substantial improvements over the alternate detection method requiring the use of wavelength shifters and photomultiplier tubes.

Luke, P.N.; Haller, E.E.; Steiner, H.M.

1982-05-01

271

IR Imaging Using Arrays of SiO2 Micromechanical Detectors  

SciTech Connect

In this letter, we describe the fabrication of an array of bimaterial detectors for infrared (IR) imaging that utilize SiO2 as a structural material. All the substrate material underneath the active area of each detector element was removed. Each detector element incorporates an optical resonant cavity layer in the IR absorbing region of the sensing element. The simplified microfabrication process requires only four photolithographic steps with no wet etching or sacrificial layers. The thermomechanical deflection sensitivity was 7.9 10-3 rad/K which corresponds to a noise equivalent temperature difference (NETD) of 2.9 mK. In the present work the array was used to capture IR images while operating at room temperature and atmospheric pressure and no need for vacuum packaging. The average measured NETD of our IR detector system was approximately 200 mK but some sensing elements exhibited an NETD of 50 mK.

Grbovic, Dragoslav [ORNL; Lavrik, Nickolay V [ORNL; Rajic, Slobodan [ORNL; Datskos, Panos G [ORNL; Hunter, Scott Robert [ORNL

2012-01-01

272

Infrared imaging using arrays of SiO2 micromechanical detectors.  

PubMed

In this Letter, we describe the fabrication of an array of bimaterial detectors for infrared (IR) imaging that utilize SiO(2) as a structural material. All the substrate material underneath the active area of each detector element was removed. Each detector element incorporates an optical resonant cavity layer in the IR-absorbing region of the sensing element. The simplified microfabrication process requires only four photolithographic steps with no wet etching or sacrificial layers. The thermomechanical deflection sensitivity was 7.9×10(-3) rad/K, which corresponds to a noise equivalent temperature difference (NETD) of 2.9 mK. In the present work, the array was used to capture IR images while operating at room temperature and atmospheric pressure without the need for vacuum packaging. The average measured NETD of our IR detector system was approximately 200 mK, but some sensing elements exhibited an NETD of 50 mK. PMID:23027247

Datskos, P G; Lavrik, N V; Hunter, S R; Rajic, S; Grbovic, D

2012-10-01

273

High-efficiency microstructured semiconductor neutron detectors that are arrayed, dual-integrated, and stacked.  

PubMed

Silicon diodes with large aspect ratio 3D microstructures backfilled with 6LiF show a significant increase in neutron detection efficiency beyond that of conventional thin-film coated planar devices. Described in this work are advancements in the technology using detector stacking methods and summed-detector 6×6-element arraying methods to dramatically increase the sensitivity to thermal neutrons. The intrinsic detection efficiency of the 6×6 array for normal-incident 0.0253 eV neutrons was found 6.8% compared against a calibrated 3He proportional counter. PMID:22365111

Bellinger, Steven L; Fronk, Ryan G; Sobering, Timothy J; McGregor, Douglas S

2012-07-01

274

The 20 element HgI2 energy dispersive x ray array detector system  

NASA Astrophysics Data System (ADS)

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.

Iwanczyk, J. A.; Dorri, N.; Wang, M.; Szczebiot, R. W.; Dabrowski, A. J.; Hedman, B.; Hodgson, K. O.; Patt, B. E.

1991-11-01

275

Infrared detector arrays with multiplexing cryogenic read-out electronics for Isophot  

NASA Astrophysics Data System (ADS)

Cryogenic read-out electronic circuits are developed in a CMOS technology for the multiplexing operation (at temperatures of 4 K and below) of extrinsic photoconducting detectors and detector arrays of Ge and Si in the Infrared Space Observatory instrument Isophot, covering the wavelength region 10-200 microns. Measurements on the 66-element spectroscopic array Isophot-S2 show an NEP around 4 x 10 to the -17th W/sq rt Hz and a voltage responsivity of 100 TV/Ws in low-background operation.

Engemann, D.; Faymonville, R.; Felten, R.; Frenzl, O.; Meyer, K.

1989-05-01

276

Silicon technology in ion detection--a high resolution detector array  

NASA Astrophysics Data System (ADS)

A new ion detecto array integrated on a silicon chip with a high spatial resolution has been designed at Aberystwyth. Integrated circuits are mounted on a ceramic substrate beneath a microchannel plate electron multiplier giving a small, light, low power, very low noise module. An array containing 384 detectors with a spatial resolution of 25 microns has been fully tested and test results are presented.

Birkinshaw, K.; Langstaff, D. P.

1994-04-01

277

Development of a mercuric iodide detector array for medical imaging applications  

Microsoft Academic Search

A nineteen element mercuric iodide (HgI2) detector array has been developed as a prototype for a larger (169 element) array, which is intended for use as an intra-operative gamma camera (IOGC). This work is motivated by the need for identifying and removing residual tumor cells after the removal of bulk tumor, while sparing normal tissue. Prior to surgery, a tumor

Bradley E Patt; Jan S Iwanczyk; Martin P Tornai; Craig S Levin; Edward J Hoffman

1995-01-01

278

Advanced numerical modeling and hybridization techniques for third-generation infrared detector pixel arrays  

NASA Astrophysics Data System (ADS)

Infrared (IR) detectors are well established as a vital sensor technology for military, defense and commercial applications. Due to the expense and effort required to fabricate pixel arrays, it is imperative to develop numerical simulation models to perform predictive device simulations which assess device characteristics and design considerations. Towards this end, we have developed a robust three-dimensional (3D) numerical simulation model for IR detector pixel arrays. We used the finite-difference time-domain technique to compute the optical characteristics including the reflectance and the carrier generation rate in the device. Subsequently, we employ the finite element method to solve the drift-diffusion equations to compute the electrical characteristics including the I(V) characteristics, quantum efficiency, crosstalk and modulation transfer function. We use our 3D numerical model to study a new class of detector based on the nBn-architecture. This detector is a unipolar unity-gain barrier device consisting of a narrow-gap absorber layer, a wide-gap barrier layer, and a narrow-gap collector layer. We use our model to study the underlying physics of these devices and to explain the anomalously long lateral collection lengths for photocarriers measured experimentally. Next, we investigate the crosstalk in HgCdTe photovoltaic pixel arrays employing a photon-trapping (PT) structure realized with a periodic array of pillars intended to provide broadband operation. The PT region drastically reduces the crosstalk; making the use of the PT structures not only useful to obtain broadband operation, but also desirable for reducing crosstalk, especially in small pitch detector arrays. Then, the power and flexibility of the nBn architecture is coupled with a PT structure to engineer spectrally filtering detectors. Last, we developed a technique to reduce the cost of large-format, high performance HgCdTe detectors by nondestructively screen-testing detector arrays prior to their final hybridization onto expensive silicon read-out integrated circuit (ROIC) chips. The approach is to temporarily hybridize each candidate HgCdTe detector array to a standard reusable ROIC for complete screen testing. We tested the technique by temporarily hybridizing LPE grown HgCdTe test chips to fan-out boards and characterizing their performance.

Schuster, Jonathan

279

Germanium blocked-impurity-band detector arrays - Unpassivated devices with bulk substrates  

NASA Technical Reports Server (NTRS)

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.

Watson, Dan M.; Guptill, Matthew T.; Huffman, James E.; Krabach, Timothy N.; Raines, S. N.; Satyapal, Shobita

1993-01-01

280

Circuit for high resolution decoding of multi-anode microchannel array detectors  

NASA Technical Reports Server (NTRS)

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.

Kasle, David B. (inventor)

1995-01-01

281

Instrumentation and performance of the water Cherenkov detector array at Sierra La Negra site  

NASA Astrophysics Data System (ADS)

We present results from the operation of the high mountain array of 4 water Cherenkov detectors located at 4550 m. a.s.l. located at Sierra Negra mountain (N 18 59.1, W 97 18.76 ) near of Puebla city in Mexico. The detectors consist of 4 light-tight cylindrical containers of 4 m2 cross section separated 25m. The vertices of the array form a triangle with one detector in the middle. The detector containers are filled with 5000 l of purified water and have a 5'' photomultiplier (EMI model 9030 A) facing down along the cylindrical axes. The acquisition electronics consists of scalers counting the number of particles every 5 ms, and an osciloscope used to fully record the traces of the four signals coming from the water Cherenkov detectors. The trigger signals correspond to photon candidate coming from a selected direction with an accuracy lower than one degree. Data and preliminary analysis are described corresponding to the last six months when operation of this detector array has been stable.

Salazar, H.; Alvarez, C.; Martinez, O.; et al.

282

Adaptive non-uniformity correction method based on temperature for infrared detector array  

NASA Astrophysics Data System (ADS)

The existence of non-uniformities in the responsitivity of the element array is a severe problem typical to common infrared detector. These non-uniformities result in a "curtain'' like fixed pattern noises (FPN) that appear in the image. Some random noise can be restrained by the method kind of equalization method. But the fixed pattern noise can only be removed by .non uniformity correction method. The produce of non uniformities of detector array is the combined action of infrared detector array, readout circuit, semiconductor device performance, the amplifier circuit and optical system. Conventional linear correction techniques require costly recalibration due to the drift of the detector or changes in temperature. Therefore, an adaptive non-uniformity method is needed to solve this problem. A lot factors including detectors and environment conditions variety are considered to analyze and conduct the cause of detector drift. Several experiments are designed to verify the guess. Based on the experiments, an adaptive non-uniformity correction method is put forward in this paper. The strength of this method lies in its simplicity and low computational complexity. Extensive experimental results demonstrate the disadvantage of traditional non-uniformity correct method is conquered by the proposed scheme.

Zhang, Zhijie; Yue, Song; Hong, Pu; Jia, Guowei; Lei, Bo

2013-09-01

283

High performance SPAD array detectors for parallel photon timing applications  

NASA Astrophysics Data System (ADS)

Over the past few years there has been a growing interest in monolithic arrays of single photon avalanche diodes (SPAD) for spatially resolved detection of faint ultrafast optical signals. SPADs implemented in planar technologies offer the typical advantages of microelectronic devices (small size, ruggedness, low voltage, low power, etc.). Furthermore, they have inherently higher photon detection efficiency than PMTs and are able to provide, beside sensitivities down to single-photons, very high acquisition speeds. Although currently available silicon devices reached remarkable performance, nevertheless further improvements are needed in order to meet the requirements of most demanding timeresolved techniques, it is necessary to face problems like electrical crosstalk between adjacent pixel, high detection efficiency in the red spectral range, large area, low dark counting rate. Moreover to develop array with high number of pixel became more and more important to develop all the TCSPC electronics with picosecond resolution to create a new family of detection system for TCSPC applications. Recent advances in our research on single photon time resolved array is here presented.

Rech, I.; Cammi, C.; Crotti, M.; Gulinatti, A.; Maccagnani, P.; Ghioni, M.; Cova, S.

2011-10-01

284

Development and test of photon-counting microchannel plate detector arrays for use on space telescopes  

NASA Technical Reports Server (NTRS)

The full sensitivity, dynamic range, and photometric stability of microchannel array plates(MCP) are incorporated into a photon-counting detection system for space operations. Components of the system include feedback-free MCP's for high gain and saturated output pulse-height distribution with a stable response; multi-anode readout arrays mounted in proximity focus with the output face of the MCP; and multi-layer ceramic headers to provide electrical interface between the anode array in a sealed detector tube and the associated electronics.

Timothy, J. G.

1976-01-01

285

Silicon Wafer-Scale Substrate for Microshutters and Detector Arrays  

NASA Technical Reports Server (NTRS)

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.

Jhabvala, Murzy; Franz, David E.; Ewin, Audrey J.; Jhabvala, Christine; Babu, Sachi; Snodgrass, Stephen; Costen, Nicholas; Zincke, Christian

2009-01-01

286

High-performance ferroelectric and magnetoresistive materials for next-generation thermal detector arrays  

NASA Astrophysics Data System (ADS)

This paper discusses the potential thermal imaging performance achievable from thermal detector arrays and concludes that the current generation of thin-film ferroelectric and resistance bolometer based detector arrays are limited by the detector materials used. It is proposed that the next generation of large uncooled focal plane arrays will need to look towards higher performance detector materials - particularly if they aim to approach the fundamental performance limits and compete with cooled photon detector arrays. Two examples of bolometer thin-film materials are described that achieve high performance from operating around phase transitions. The material Lead Scandium Tantalate (PST) has a paraelectric-to-ferroelectric phase transition around room temperature and is used with an applied field in the dielectric bolometer mode for thermal imaging. PST films grown by sputtering and liquid-source CVD have shown merit figures for thermal imaging a factor of 2 to 3 times higher than PZT-based pyroelectric thin films. The material Lanthanum Calcium Manganite (LCMO) has a paramagnetic to ferromagnetic phase transition around -20oC. This paper describes recent measurements of TCR and 1/f noise in pulsed laser-deposited LCMO films on Neodymium Gallate substrates. These results show that LCMO not only has high TCR's - up to 30%/K - but also low 1/f excess noise, with bolometer merit figures at least an order of magnitude higher than Vanadium Oxide, making it ideal for the next generation of microbolometer arrays. These high performance properties come at the expense of processing complexities and novel device designs will need to be introduced to realize the potential of these materials in the next generation of thermal detectors.

Todd, Michael A.; Donohue, Paul P.; Watton, Rex; Williams, Dennis J.; Anthony, Carl J.; Blamire, Mark G.

2002-12-01

287

Dual source and dual detector arrays tetrahedron beam computed tomography for image guided radiotherapy.  

PubMed

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. PMID:24434681

Kim, Joshua; Lu, Weiguo; Zhang, Tiezhi

2014-02-01

288

Detector Arrays for the James Webb Space Telescope Near-Infrared Spectrograph  

NASA Technical Reports Server (NTRS)

The James Webb Space Telescope's (JWST) Near Infrared Spectrograph (NIRSpec) incorporates two 5 micron cutoff (lambda(sub co) = 5 microns) 2048x2048 pixel Teledyne HgCdTe HAWAII-2RG sensor chip assemblies. These detector arrays, and the two Teledyne SIDECAR application specific integrated circuits that control them, are operated in space at T approx. 37 K. In this article, we provide a brief introduction to NIRSpec, its detector subsystem (DS), detector readout in the space radiation environment, and present a snapshot of the developmental status of the NIRSpec DS as integration and testing of the engineering test unit begins.

Rauscher, Bernard J.; Alexander, David; Brambora, Clifford K.; Derro, Rebecca; Engler, Chuck; Fox, Ori; Garrison, Matthew B.; Henegar, Greg; Hill, robert J.; Johnson, Thomas; Lindler, Don J.; Manthripragada, Sridhar S.; Marshall, Ceryl; Mott, Brent; Parr, Thomas M.; Roher, Wayne D.; Shakoorzadeh, Kamdin B.; Smith, Miles; Waczynski, Augustyn; Wen, Yiting; Wilson, Donna; Xia-Serafino, Wei

2007-01-01

289

Laboratory characterization of direct readout Si:Sb and Si:Ga infrared detector arrays  

NASA Technical Reports Server (NTRS)

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.

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

290

X-ray source considerations in operation of digital detector arrays  

NASA Astrophysics Data System (ADS)

Digital Detector Arrays (DDA) are increasingly replacing film in radiography applications. Standards exist for characterizing the performance of these detectors, and for using them in specific inspections. We have observed that the selection of the x-ray source to use with these detectors can also have a significant influence on the performance. We look at differences between standard, and micro-focus x-ray tubes, and end-window vs. side-window micro-focus tubes. We find that for best results, one must calibrate the DDA for the source settings used during an inspection. This is particularly true for variable-focus sources.

Jensen, Terrence; Wendt, Scott

2014-02-01

291

A Current Mode Detector Array for Gamma-Ray Asymmetry Measurements  

E-print Network

We have built a CsI(Tl) gamma-ray detector array for the NPDGamma experiment to search for a small parity-violating directional asymmetry in the angular distribution of 2.2 MeV gamma-rays from the capture of polarized cold neutrons by protons with a sensitivity of several ppb. The weak pion-nucleon coupling constant can be determined from this asymmetry. The small size of the asymmetry requires a high cold neutron flux, control of systematic errors at the ppb level, and the use of current mode gamma-ray detection with vacuum photo diodes and low-noise solid-state preamplifiers. The average detector photoelectron yield was determined to be 1300 photoelectrons per MeV. The RMS width seen in the measurement is therefore dominated by the fluctuations in the number of gamma rays absorbed in the detector (counting statistics) rather than the intrinsic detector noise. The detectors were tested for noise performance, sensitivity to magnetic fields, pedestal stability and cosmic background. False asymmetries due to gain changes and electronic pickup in the detector system were measured to be consistent with zero to an accuracy of $10^{-9}$ in a few hours. We report on the design, operating criteria, and the results of measurements performed to test the detector array.

M. T. Gericke; C. Blessinger; J. D. Bowman; R. C. Gillis; J. Hartfield; T. Ino; M. Leuschner; Y. Masuda; G. S. Mitchell; S. Muto; H. Nann; S. A. Page; S. I. Penttil{ä}}; W. D. Ramsay; P. -N. Seo; W. M. Snow; J. Tasson; W. S. Wilburn

2004-11-11

292

Two-color thermal detector with thermal chopping for infrared focal-plane arrays.  

PubMed

Micromachined thermal infrared (IR) detectors are emerging into the marketplace to provide high-performance thermal (IR) imagery at low cost. Thermal detectors can be improved when a tunable wavelength response is provided and when a thermal chopper is incorporated into the detector by use of microelectromechanical (MEM) elements. Most thermal detectors require a chopper, continuous synchronous chopping in the case of pyroelectric detectors, or asynchronous chopping in the case of staring microbolometers. Mechanical choppers are bulky and costly. We present the fundamental principles of micromachined thermal detectors that possess tunable wavelength or color response and a technique for thermal chopping. A micromirror, switching between two spatial positions under the detector, provides a response to two wavelength windows by tuning the optical resonant cavity. The image can then be integrated at the readout level to achieve a multicolor IR picture. A thermal MEM chopper can be used instead of a mechanical chopper to maintain the same video frame rate and to allow for an interlaced resetting of staring thermal arrays. Unlike the second generation of uncooled IR arrays, the actual temperature of objects can be obtained by a comparison of the response in two wavelength windows, in addition to the direct measurement of IR power that they radiate in the entire 8-14-microm spectral region. PMID:18357274

Leonov, V N; Butler, D P

2001-06-01

293

Digital Radiography and Computed Tomography Project -- Fully Integrated Linear Detector ArrayStatus Report  

SciTech Connect

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.

Tim Roney; Robert Seifert; Bob Pink; Mike Smith

2011-09-01

294

Development of 256 x 256 Element Impurity Band Conduction Infrared Detector Arrays for Astronomy  

NASA Technical Reports Server (NTRS)

This report describes the work performed on a one and a half year advance technology program to develop Impurity Band Conduction (IBC) detectors with very low dark current, high quantum efficiency, and with good repeatable processes. The program fabricated several epitaxial growths of Si:As detecting layers from 15 to 35 microns thick and analyzed the performance versus the thickness and the Arsenic concentration of these epitaxial layers. Some of the epitaxial runs did not yield because of excessive residual impurities. The thicker epitaxial layers and the ones with higher Arsenic concentration resulted in good detectors with low dark currents and good quantum efficiency. The program hybridized six detector die from the best detector wafers to a low noise, 256 x 256 readout array and delivered the hybrids to NASA Ames for a more detailed study of the performance of the detectors.

Domingo, George

1997-01-01

295

Characterization and simulation of linear scintillator arrays for low-energy x-ray detection  

NASA Astrophysics Data System (ADS)

Current x-ray imaging in many industrial and medical applications uses different scintillator materials coupled to photodiode arrays. Knowledge of the light distribution and photoelectron signal allows for the improvement of the imaging properties of such devices. We have measured and simulated the pixel scintillation light distribution collected by the photodiode arrays for four commercial scintillator arrays made of cesium iodide, cadmium tungstate and gadolinium oxysulfide with pitches of 0.8 mm and 1.6 mm. We used a collimated low-energy x-ray beam to study the collected signal in each array element and the effective fill factors determined from the photodiode geometry, backing material and radiation transport in the scintillator. A proper description of the optical parameters of these detectors provides excellent agreement of the experimental results with Monte Carlo simulations performed with MANTIS.

Franco, L.; Gómez, F.; Badano, A.

2008-11-01

296

Search for ultra-high energy photons using Telescope Array surface detector  

SciTech Connect

We search for ultra-high energy photons by analyzing geometrical properties of shower fronts of events registered by the Telescope Array surface detector. By making use of an event-by-event statistical method, we derive an upper limit on the absolute flux of primary photons with energies above 10{sup 19} eV.

Rubtsov, G. I.; Troitsky, S. V. [Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, 117312 (Russian Federation); Ivanov, D.; Stokes, B. T. [Rutgers - State University of New Jersey, Piscataway (United States); Thomson, G. B. [University of Utah, High Energy Astrophysics Institute, Salt Lake City, Utah (United States)

2011-09-22

297

Photodiode and photomultiplier areal sensitivity anomalies  

NASA Technical Reports Server (NTRS)

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.

Youngbluth, O., Jr.

1977-01-01

298

Charge Sharing and Charge Loss in a Cadmium-Zinc-Telluride Fine-Pixel Detector Array  

NASA Technical Reports Server (NTRS)

Because of its high atomic number, room temperature operation, low noise, and high spatial resolution a Cadmium-Zinc-Telluride (CZT) multi-pixel detector is ideal for hard x-ray astrophysical observation. As part of on-going research at MSFC (Marshall Space Flight Center) to develop multi-pixel CdZnTe detectors for this purpose, we have measured charge sharing and charge loss for a 4x4 (750micron pitch), lmm thick pixel array and modeled these results using a Monte-Carlo simulation. This model was then used to predict the amount of charge sharing for a much finer pixel array (with a 300micron pitch). Future work will enable us to compare the simulated results for the finer array to measured values.

Gaskin, J. A.; Sharma, D. P.; Ramsey, B. D.; Six, N. Frank (Technical Monitor)

2002-01-01

299

Thermal IR imaging system using a self-scanned HgCdTe/CCD detector array  

NASA Technical Reports Server (NTRS)

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.

Husain-Abidi, A. S.; Ostrow, H.; Rubin, B.

1980-01-01

300

Measurement of the UHECR Energy Spectrum by the Telescope Array Fluorescence Detectors  

NASA Astrophysics Data System (ADS)

Ultra-high-energy cosmic rays (UHECRs), subatomic charged particles of extraterrestrial origin and with kinetic energies near or exceeding 10^18 eV, are very rare. The Telescope Array (TA) experiment in western Utah is the northern hemisphere's largest UHECR detector, and consists of three atmospheric fluorescence detectors (FDs) and a ground array of 507 scintillator detectors. In stand-alone ``monocular'' operation, the FDs can observe the widest range in primary UHECR energies. One FD employs refurbished hardware from the High-Resolution Fly's Eye experiment; the remaining two FDs were designed for TA and employ new hardware and analysis. We will present the UHECR energy spectrum measured by the FDs in monocular mode using data collected during the first four years of operation.

Stroman, Thomas; Bergman, Douglas

2013-04-01

301

Recent progress with multi-anode microchannel array detector systems. [for use in instruments on telescopes  

NASA Technical Reports Server (NTRS)

The construction and modes of operation of Multi-Anode Microchannel Arrays (MAMA's) are briefly reviewed. The MAMA detectors, which are a family of photoelectric, photon-counting array detectors being developed specifically for use in instruments on ground-based and space-borne telescopes, combine the high sensitivity and photometric stability of a conventional channel electron multiplier with a high-resolution imaging capability. The MAMA detectors feature low applied potential (less than 3 kV), high gain (greater than 10 to the 6th electrons/pulse), an absolute event timing accuracy of 100 ns or better, a very long count lifetime (greater than 2.5 x 10 to the 11th counts/sq mm), and a power consumption of less than 30 W for a complete system

Timothy, J. G.

1982-01-01

302

Status of LWIR HgCdTe infrared detector technology  

NASA Technical Reports Server (NTRS)

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.

Reine, M. B.

1990-01-01

303

High-resolution ultrasonic imaging using an etalon detector array  

PubMed Central

A photoacoustic imaging system was built and tested to demonstrate the feasibility of high-resolution low-noise ultrasonic imaging based on parallel detection using polymer etalons. Its capability of detecting ultrasound at different elements simultaneously in the optical end was verified by imaging three 49 ?m beads. An average noise-equivalent pressure of 3.6 kPa over 50 MHz for 50 ?m diameter detection elements in a two-dimensional array with a diameter of 1.35 mm and a detection bandwidth of 75 MHz at –3 dB was measured. These results demonstrate the potential of polymer etalons for high-frame-rate high-resolution three-dimensional photoacoustic and ultrasound pulse-echo imaging. PMID:19529842

Huang, Sheng-Wen; Hou, Yang; Ashkenazi, Shai; O'Donnell, Matthew

2008-01-01

304

CdZnTe and CdTe detector arrays for hard X-ray and gamma-ray astronomy  

Microsoft Academic Search

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

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

305

An Asic for High-Speed and High-Resolution Decoding of MultiAnode Microchannel Array Detectors  

Microsoft Academic Search

The Multi-Anode Microchannel Array (MAMA) is a microchannel plate-based photon-counting detector with applications in ground-based and space-based astronomy. The detector requires a digital decoder to determine the position of each photon event, and the decoding algorithm that associates a given event with the appropriate pixel is determined by the geometry of the detector's anode array. An Application Specific Integrated Circuit

David Benjamin Kasle

1992-01-01

306

NORSAR Final Scientific Report Adaptive Waveform Correlation Detectors for Arrays: Algorithms for Autonomous Calibration  

SciTech Connect

Correlation detection is a relatively new approach in seismology that offers significant advantages in increased sensitivity and event screening over standard energy detection algorithms. The basic concept is that a representative event waveform is used as a template (i.e. matched filter) that is correlated against a continuous, possibly multichannel, data stream to detect new occurrences of that same signal. These algorithms are therefore effective at detecting repeating events, such as explosions and aftershocks at a specific location. This final report summarizes the results of a three-year cooperative project undertaken by NORSAR and Lawrence Livermore National Laboratory. The overall objective has been to develop and test a new advanced, automatic approach to seismic detection using waveform correlation. The principal goal is to develop an adaptive processing algorithm. By this we mean that the detector is initiated using a basic set of reference ('master') events to be used in the correlation process, and then an automatic algorithm is applied successively to provide improved performance by extending the set of master events selectively and strategically. These additional master events are generated by an independent, conventional detection system. A periodic analyst review will then be applied to verify the performance and, if necessary, adjust and consolidate the master event set. A primary focus of this project has been the application of waveform correlation techniques to seismic arrays. The basic procedure is to perform correlation on the individual channels, and then stack the correlation traces using zero-delay beam forming. Array methods such as frequency-wavenumber analysis can be applied to this set of correlation traces to help guarantee the validity of detections and lower the detection threshold. In principle, the deployment of correlation detectors against seismically active regions could involve very large numbers of very specific detectors. To meet this challenge, we have examined two strategies: (1) use of subspace detectors, a multi-dimensional extension of correlators, which allow representation and detection of signals exhibiting some degree of variation; and (2) autonomous calibration of many subspace and correlation detectors in an adaptive detection framework, subject to analyst review. Because correlation detectors are relatively new to seismology, a significant amount of research on how to tune these detectors has been needed to address later calibration efforts that will arise as they are adopted for operational use. We have approached these challenges by carrying out a number of case studies, encompassing various monitoring scenarios such as earthquake aftershock sequences and swarms, recurring mining explosions, other types of explosions, and rockbursts. We have studied several different geographical regions (the European Arctic, Central Asia, and the western United States). We have drawn on available Ground Truth data in assessing the results of the various processing schemes. In all cases, we have benefited from the high-quality seismic arrays or networks available in these regions, and we have thus been able to evaluate the performance of array-based correlation processing under a variety of conditions. The main results of the project are summarized as follows: (1) Array-based waveform correlation has been demonstrated to lower significantly detection thresholds in comparison with standard single-channel waveform correlation. (2) Frequency-wavenumber analysis of the correlation traces on a small-aperture array provides an effective method for screening out a certain category of false alarms, and can therefore be used to improve detector sensitivity by lowering the threshold for automatic array detection. (3) We have developed and tested a framework for autonomous correlation detection. The framework comprises a set of conventional (STA/LTA) detectors on a collection of array beams, augmented by correlation and subspace detectors. The detectors are applied in parallel. (4) We have expe

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

2009-04-16

307

3D Dose Verification Using Tomotherapy CT Detector Array  

SciTech Connect

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.

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

308

Sol-gel derived barium strontium titanate thin films for uncooled infrared detector array applications  

NASA Astrophysics Data System (ADS)

Columnar Ba0.8Sr0.2TiO3 films with a grain size of 100 to 200 nm have been obtained from a 0.05M precursor solution. Electrical measurements indicated these films showed a pyroelectric coefficient of 4.1 × 10-4 C/m2K at room temperature, and a leakage current of 1.42 × 10-7 A/cm2 under 100 kV/cm electrical field. The Ba0.8Sr0.2TiO3 films have been used for fabricating a 1 × 16 elements infrared detector linear array with a bulk micromachining technique. The array pixels with a sensitive area of 500 × 300 ?m2 have a detectivity of 2.3 × 108 cmHz½W-1 at 23°C and 35 Hz. By using these infrared detector arrays, thermal images were successfully obtained at room temperature. These results indicate the sol-gel derived Ba0.8Sr0.2TiO3 films from a 0.05M precursor solution are suitable for uncooled infrared detector array applications.

Cheng, Jian-Gong; Tang, Jun; Chu, Junhao

2002-12-01

309

Integration of PMCC detector in seismic operational automatic processing chain. Validation on MMAI array.  

NASA Astrophysics Data System (ADS)

The PMCC method (Progressive Multi-Channels Correlation; Cansi, 1995) has been applied to the Mount Meiron array (MMAI station code) with the perspective to improve data processing such as detection and categorization. PMCC algorithm is based on a study of the cross-correlation functions between each stations of the array, which leads to a consistent set of time-delays when a seismic phase is present. The set of time-delays allows calculation of horizontal velocity and azimuth of arrival wavefront. We show that PMCC detector with a configuration designed for P-wave characteristics allows improving significantly the detection threshold of MMAI array compared to standard seismic-to-noise ratio detectors. |In addition a comparison of pmcc performance for several International Monitoring System (IMS) to the current array detector used by the International Data Center (IDC) is given. Moreover, the analysis of P-wave parameters gives a first insight to the categorization issue. Statistic approach applied to PMCC results allow identification of seismic sequence and differentiation with independent seismic or noise detections. Categorization is essential to reduce drastically the number of detections, in order to integer PMCC results in operational automatic detection processing chain. We propose also a python routine for uploading pmcc detections into database for storage compatible with CTBTO environment.

Cano, Y.; Ben-Horin, Y.

2012-04-01

310

The performance of 2D array detectors for light sheet based fluorescence correlation spectroscopy.  

PubMed

Single plane illumination microscopy based fluorescence correlation spectroscopy (SPIM-FCS) is a new method for imaging FCS in 3D samples, providing diffusion coefficients, transport, flow velocities and concentrations in an imaging mode. SPIM-FCS records correlation functions over a whole plane in a sample, which requires array detectors for recording the fluorescence signal. Several types of image sensors are suitable for FCS. They differ in properties such as effective area per pixel, quantum efficiency, noise level and read-out speed. Here we compare the performance of several low light array detectors based on three different technologies: (1) Single-photon avalanche diode (SPAD) arrays, (2) passive-pixel electron multiplying charge coupled device (EMCCD) and (3) active-pixel scientific-grade complementary metal oxide semiconductor cameras (sCMOS). We discuss the influence of the detector characteristics on the effective FCS observation volume, and demonstrate that light sheet based SPIM-FCS provides absolute diffusion coefficients. This is verified by parallel measurements with confocal FCS, single particle tracking (SPT), and the determination of concentration gradients in space and time. While EMCCD cameras have a temporal resolution in the millisecond range, sCMOS cameras and SPAD arrays can extend the time resolution of SPIM-FCS down to 10 ?s or lower. PMID:23571955

Singh, Anand Pratap; Krieger, Jan Wolfgang; Buchholz, Jan; Charbon, Edoardo; Langowski, Jörg; Wohland, Thorsten

2013-04-01

311

Materials preparation and fabrication of pyroelectric polymer/silicon MOSFET detector arrays. Final report  

SciTech Connect

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.

Bloomfield, P. [Drexel Univ., Philadelphia, PA (United States). Dept. of Materials Engineering

1992-03-27

312

Underground Water Cherenkov Muon Detector Array with the Tibet Air Shower Array for Gamma-Ray Astronomy in the 100 TeV Region  

E-print Network

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.

The Tibet AS Gamma Collaboration; M. Amenomori

2006-11-01

313

Underground Water Cherenkov Muon Detector Array with the Tibet Air Shower Array for Gamma-Ray Astronomy in the 100 TeV Region  

E-print Network

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.

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; Lü, 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; Saitô, 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

314

Detection and localization of particle-emitting sources with compound-eye inspired detector arrays  

NASA Astrophysics Data System (ADS)

We develop methods to detect and localize particle-emitting sources using detector arrays that are inspired by biological compound eyes. The sources of interest may be optical, nuclear, or cosmic; they emit particles such as visible photons, neutrons, protons, or charged particles. Our results may have wide applications to artificial vision, which can be important in robotics (robot vision) or medicine (e.g., artificial eyes for the blind); security, where the detection of nuclear materials is needed; or astronomy. This dissertation consists of three parts. First, we detect a far-field particle source using two directional detector arrays: cubic and spherical. We propose a mean-difference test (MDT) detector, analyze its statistical performance, and show that the MDT has a number of advantages over the generalized likelihood- ratio test (GLRT). Second, we localize the source by proposing a novel biologically inspired detector array, whose configuration generalizes the compound eye of insects. This array combines the advantages of compound eyes (e.g., large field-of-view) and human eyes (e.g., high angular resolution). Based on a statistical model of the array measurements, we analyze the array performance by computing the Cramérao bound (CRB) on the error in estimating the source direction. We also derive lower bounds on the mean-square angular error (MSAE) of the source localization and investigate the MSAE of two source- direction estimators. Numerical examples, including the optimal array design, are presented to further illustrate the array performance. Third, we derive a statistical angular resolution limit (ARL) on resolving two closely spaced point sources in a three-dimensional frame, which is applicable to various measurement models (e.g., radar, sonar, or astronomy). Using the asymptotic analysis of the GLRT, we derive the ARL with constraints on the probabilities of false alarm and detection. Our results give explicit analytical expression for the ARL that is proportional to the square root of the CRB on the angular source separation, or equivalently to the lower bound on the MSAE.

Liu, Zhi

2007-08-01

315

The blocking probability of Geiger-mode avalanche photo-diodes  

NASA Astrophysics Data System (ADS)

When a photon is detected by a Geiger-mode avalanche photo-diode (GMAPD), the detector is rendered inactive, or blocked, for a certain period of time. In this paper we derive the blocking probability for a GMAPD whose input is either an unmodulated, Bernoulli modulated or pulse-position-modulated (PPM) Poisson process. We demonstrate how the PPM and Bernoulli cases differ, illustrating that the PPM blocking probability is larger than the Bernoulli. The blocking rates may be decreased by focusing the incident light on an array of detectors. We show that the binomial output statistics of an array of GMAPDs may be modeled as Poisson and measure the error in this approximation via the relative entropies of the two distributions.

Moision, Bruce; Srinivasan, Meera; Hamkins, Jon

2005-08-01

316

High-dynamic-range coherent diffractive imaging: ptychography using the mixed-mode pixel array detector  

PubMed Central

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 µm?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 ‘still’ 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

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

317

High-dynamic-range coherent diffractive imaging: ptychography using the mixed-mode pixel array detector.  

PubMed

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 × 10(8) 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 × 10(10)?photons µm(-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 `still' 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

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

2014-09-01

318

Testing the Large-area multi-Institutional Scintillator Array (LISA) Neutron Detector  

NASA Astrophysics Data System (ADS)

The 144 detector modules comprising the Large-area multi-Institutional Scintillator Array (LISA) neutron detector were tested at each of the nine primarily undergraduate institutions. Each module is a 200 cm by 10 cm by 10 cm bar of EJ-200 organic plastic scintillator a with a photomultiplier tube mounted on each end. We used cosmic rays both to ensure that each module was light tight as well as to characterize position and time resolution. In addition, we measured each module's light attenuation using gamma sources. Results will be presented.

Nagi, T. B.; Rethman, K. M.; Purtell, K. A.; Haagsma, A. J.; Deroo, C.; Jacobson, M.; Kuhn, S.; Peters, A. R.; Ndong, M.; Stewart, S. A.; Torstrick, Z.; Anthony, R.; Chen, H.; Howe, A.; Badger, N. S.; Miller, M. D.; Foster, B. J.; Rice, L. C.; Vest, C.; Aulie, A. B.; Grovom, A.; Elliot, L.; Kasavan, P.

2010-11-01

319

DALI2: A NaI(Tl) detector array for measurements of ? rays from fast nuclei  

NASA Astrophysics Data System (ADS)

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.

Takeuchi, S.; Motobayashi, T.; Togano, Y.; Matsushita, M.; Aoi, N.; Demichi, K.; Hasegawa, H.; Murakami, H.

2014-11-01

320

The cosmology large angular scale surveyor (CLASS): 38-GHz detector array of bolometric polarimeters  

NASA Astrophysics Data System (ADS)

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.

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; Dünner, 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

321

MOCVD growth of ZnO nanowire arrays for advanced UV detectors  

NASA Astrophysics Data System (ADS)

Zinc oxide (ZnO) is a biocompatible and versatile functional material having a bandgap of 3.37 eV that exhibits both semiconducting and piezoelectric properties and has a diverse group of growth morphologies. We have grown highly ordered vertical arrays of ZnO nanowires (NWs) using a metal organic chemical vapor deposition (MOCVD) growth process on various substrates. The NWs were grown on p-Si (100), SiO2, and m-plane sapphire substrates. The structural and optical properties of the grown vertically aligned ZnO NW arrays were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL) measurements. The unique diffraction pattern for ZnO (002) concurred with the SEM inspection indicating vertical orientation of the NWs. UV detectors based on ZnO NWs offer high UV sensitivity and low visible sensitivity for applications such as missile plume detection and threat warning. Compared to the photomultiplier tubes (PMTs) prevalent in current missile warning systems, the NW detector arrays are expected to exhibit low noise, extended lifetimes, and low power requirements for UV detector applications.

Rivera, Abdiel; Mazady, Anas; Zeller, John; Anwar, Mehdi; Manzur, Tariq; Sood, Ashok

2013-03-01

322

Signal encoding method for a time-of-flight PET detector using a silicon photomultiplier array  

NASA Astrophysics Data System (ADS)

The silicon photomultiplier (SiPM) is a promising photosensor for magnetic resonance (MR) compatible time-of-flight (TOF) positron emission tomography (PET) scanners. The compact size of the SiPM allows direct one-to-one coupling between the scintillation crystal and the photosensor, yielding better timing and energy resolutions than the light sharing methods that have to be used in photomultiplier tube (PMT) PET systems. However, the one-to-one coupling scheme requires a huge volume of readout and processing electronics if no electric signal multiplexing or encoding scheme is properly applied. In this paper, we develop an electric signal encoding scheme for SiPM array based TOF PET detector blocks with the aim of reducing the complexity and volume of the signal readout and processing electronics. In an M×N SiPM array, the output signal of each channel in the SiPM array is divided into two signal lines. These output lines are then tied together in row and column lines. The row and column signals are used to measure the energy and timing information (or vice versa) of each incident gamma-ray event, respectively. Each SiPM channel was directly coupled to a 3×3×20 mm3 LGSO crystal. The reference detector, which was used to measure timing, consisted of an R9800 PMT and a 4×4×10 mm3 LYSO crystal and had a single time resolution of ~200 ps (FWHM). Leading edge discriminators were used to determine coincident events. Dedicated front-end electronics were developed, and the timing and energy resolutions of SiPM arrays with different array sizes (4×4, 8×8, and 12×12) were compared. Breakdown voltage of each SiPM channel was measured using energy spectra within various bias voltages. Coincidence events were measured using a 22Na point source. The average coincidence time resolution of 4×4, 8×8, and 12×12 SiPM arrays were 316 ps, 320 ps, and 335 ps (FWHM), respectively. The energy resolution of 4×4, 8×8, and 12×12 SiPM arrays were 11.8%, 12.5%, and 12.8% (FWHM), respectively. Because of length differences between each SiPM channel and summed signal output on printed a circuit board, propagation delay of ~111 ps was observed. A signal encoding method for a TOF PET block detector using SiPMs has been developed to reduce the complexity and volume of the signal readout and processing electronics required. The proposed method showed promising results, which were measured for various SiPM array sizes.

Kwon, Sun Il; Lee, Jae Sung

2014-10-01

323

Microelectrode Arrays with Overlapped Diffusion Layers as Electroanalytical Detectors: Theory and Basic Applications  

PubMed Central

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

Tomcik, Peter

2013-01-01

324

Performance of charge-injection-device infrared detector arrays at low and moderate backgrounds  

NASA Technical Reports Server (NTRS)

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.

Mckelvey, M. E.; Mccreight, C. R.; Goebel, J. H.; Reeves, A. A.

1985-01-01

325

Development of Ta-based STJ X-ray Detector Arrays for Synchrotron Science  

NASA Astrophysics Data System (ADS)

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.

Carpenter, M. H.; Friedrich, S.; Hall, J. A.; Harris, J.; Cantor, R.

2014-08-01

326

Optimizing the use of detector arrays for measuring intensity correlations of photon pairs  

NASA Astrophysics Data System (ADS)

Intensity correlation measurements form the basis of many experiments based on spontaneous parametric down-conversion. In the most common situation, two single-photon avalanche diodes and coincidence electronics are used in the detection of the photon pairs, and the coincidence count distributions are measured by making use of some scanning procedure. Here we analyze the measurement of intensity correlations using multielement detector arrays. By considering the detector parameters such as the detection and noise probabilities, we found that the mean number of detected photons that maximizes the visibility of the two-photon correlations is approximately equal to the mean number of noise events in the detector array. We provide expressions predicting the strength of the measured intensity correlations as a function of the detector parameters and on the mean number of detected photons. We experimentally test our predictions by measuring far-field intensity correlations of spontaneous parametric down-conversion with an electron multiplying charge-coupled device camera, finding excellent agreement with the theoretical analysis.

Tasca, Daniel S.; Edgar, Matthew P.; Izdebski, Frauke; Buller, Gerald S.; Padgett, Miles J.

2013-07-01

327

Charge-coupled-device/fiberoptic taper array X-ray detector for protein crystallography  

SciTech Connect

A large area, charge-couple-device (CCD) based fiberoptic taper array detector (APS-1) has been installed at the insertion-device beamline of the Structural Biology Center at the ANL Advanced Photon Source. The detector is used in protein crystallography diffraction experiments, where the objective is to measure the position and intensity of X-ray Bragg peaks in diffraction images. Large imaging area, very high spatial resolution, high X-ray sensitivity, good detective quantum efficiency, low noise, wide dynamic range, excellent stability and short readout time are all fundamental requirements in this application. The APS-1 detector converts the two-dimensional X-ray patterns to a visible light images by a thin layer of X-ray sensitive phosphor. The phosphor coating is directly deposited on the large ends of nine fiberoptic tapers arranged in a 3x3 array. Nine, thermoelectrically cooled 1024 x 1024 pixel CCD`s image the patterns, demagnified by the tapers. After geometrical and uniformity corrections, the nine areas give a continuous image of the detector face with virtually no gaps between the individual tapers. The 18 parallel analog signal-processing channels and analog-to-digital converters assure short readout time and low readout noise.

Naday, I.; Ross, S.; Westbrook, E.M.; Zentai, G.

1997-03-01

328

X-ray analog pixel array detector for single synchrotron bunch time-resolved imaging  

PubMed Central

Dynamic X-ray studies can reach temporal resolutions limited by only the X-ray pulse duration if the detector is fast enough to segregate synchrotron pulses. An analog integrating pixel array detector with in-pixel storage and temporal resolution of around 150?ns, sufficient to isolate pulses, is presented. Analog integration minimizes count-rate limitations and in-pixel storage captures successive pulses. Fundamental tests of noise and linearity as well as high-speed laser measurements are shown. The detector resolved individual bunch trains at the Cornell High Energy Synchrotron Source at levels of up to 3.7 × 103?X-rays per pixel per train. When applied to turn-by-turn X-ray beam characterization, single-shot intensity measurements were made with a repeatability of 0.4% and horizontal oscillations of the positron cloud were detected. PMID:21335901

Koerner, Lucas J.; Gruner, Sol M.

2011-01-01

329

Numerical Simulation of the Modulation Transfer Function in HgCdTe Detector Arrays  

NASA Astrophysics Data System (ADS)

In this work, we develop a method for simulating the modulation transfer function (MTF) of infrared detector arrays, which is based on numerical evaluation of the detector physics. The finite-difference time-domain and finite element methods are used to solve the electromagnetic and electrical equations for the device, respectively. We show how the total MTF can be deconvolved to examine the effects of specific physical processes. We introduce the MTF area difference and use it to quantify the effectiveness of several crosstalk mitigation techniques in improving the system MTF. We then apply our simulation methods to two-thirds generation mercury cadmium telluride (HgCdTe) detector architectures. The methodology is general, can be implemented with commercially available software, has experimentally realizable analogs, and is extendable to other material systems and device designs.

Pinkie, Benjamin; Bellotti, Enrico

2014-08-01

330

A micro GC detector array based on chemiresistors employing various surface functionalized monolayer-protected gold nanoparticles.  

PubMed

Aspects of the design, fabrication, and characterization of a chemiresistor type of microdetector for use in conjunction with gas chromatograph are described. The detector was manufactured on silicon chips using microelectromechanical systems (MEMS) technology. Detection was based on measuring changes in resistance across a film comprised of monolayer-protected gold nanoclusters (MPCs). When chromatographic separated molecules entered the detector cell, the MPC film absorbed vapor and undergoes swelling, then the resistance changes accordingly. Thiolates were used as ligand shells to encapsulate the nano-gold core and to manipulate the selectivity of the detector array. The dimensions of the ?-detector array were 14(L)×3.9(W)×1.2(H)mm. Mixtures of eight volatile organic compounds with different functional groups and volatility were tested to characterize the selectivity of the ?-detector array. The detector responses were rapid, reversible, and linear for all of the tested compounds. The detection limits ranged from 2 to 111ng, and were related to both the compound volatility and the selectivity of the surface ligands on the gold nanoparticles. Design and operation parameters such as flow rate, detector temperature, and width of the micro-fluidic channel were investigated. Reduction of the detector temperature resulted in improved sensitivity due to increased absorption. When a wider flow channel was used, the signal-to-noise ratio was improved due to the larger sensing area. The extremely low power consumption and small size makes this ?-detector array potentially useful for the development of integrated ?-GC. PMID:22265482

Jian, Rih-Sheng; Huang, Rui-Xuan; Lu, Chia-Jung

2012-01-15

331

Performance of semi-insulating gallium arsenide X-ray pixel detectors with current-integrating readout  

Microsoft Academic Search

First images are presented from tests of a semi-insulating gallium arsenide X-ray imaging detector, flip-chip bonded to a current integrating CMOS readout chip. The detector is designed for applications in synchrotron X-ray imaging. The X-ray sensing part of the detector consists of a 150mum thick GaAs photodiode containing an array of 92×100 pixels, each 150mum by 150mum in size. Operating

P. J. Sellin; G. Rossi; M. J. Renzi; A. P. Knights; E. F. Eikenberry; M. W. Tate; S. L. Barna; R. L. Wixted; S. M. Gruner

2001-01-01

332

A compact 64-pixel CsI(T1)/Si PIN photodiode imaging module with IC readout  

SciTech Connect

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.

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

333

Two dimensional extensible array configuration for EMCCD-based solid state x-ray detectors  

PubMed Central

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 ?m2 (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 3×3 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

Sharma, P.; Vasan, S.N. Swetadri; Cartwright, A. N.; Titus, A. H.; Bednarek, D.R.; Rudin, S.

2012-01-01

334

Automated characterization of single-photon avalanche photodiode  

E-print Network

We report an automated characterization of a single-photon detector based on commercial silicon avalanche photodiode (PerkinElmer C30902SH). The photodiode is characterized by I-V curves at different illumination levels (darkness, 10 pW and 10 uW), dark count rate and photon detection efficiency at different bias voltages. The automated characterization routine is implemented in C++ running on a Linux computer.

Aina M. M. Ghazali; Audun N. Bugge; Sebastien Sauge; Vadim Makarov

2012-02-08

335

A Current Mode Detector Array for Gamma-Ray Asymmetry Measurements  

E-print Network

We have built a CsI(Tl) gamma-ray detector array for the NPDGamma experiment to search for a small parity-violating directional asymmetry in the angular distribution of 2.2 MeV gamma-rays from the capture of polarized cold neutrons by protons with a sensitivity of several ppb. The weak pion-nucleon coupling constant can be determined from this asymmetry. The small size of the asymmetry requires a high cold neutron flux, control of systematic errors at the ppb level, and the use of current mode gamma-ray detection with vacuum photo diodes and low-noise solid-state preamplifiers. The average detector photoelectron yield was determined to be 1300 photoelectrons per MeV. The RMS width seen in the measurement is therefore dominated by the fluctuations in the number of gamma rays absorbed in the detector (counting statistics) rather than the intrinsic detector noise. The detectors were tested for noise performance, sensitivity to magnetic fields, pedestal stability and cosmic background. False asymmetries due to ga...

Gericke, M T; Bowman, J D; Gillis, R C; Hartfield, J; Ino, T; Leuschner, M; Masuda, Y; Mitchell, G S; Muto, S; Nann, H; Page, S A; Penttil"a, S I; Ramsay, W D; Seo, P N; Snow, W M; Tasson, J; Wilburn, W S

2004-01-01

336

Automated Calibration Procedures for an Array of Position-resolving NaI-Detectors  

NASA Astrophysics Data System (ADS)

Recently, a new experimental setup called uc(stripsi) was constructed at Florida State University's superconducting accelerator laboratory. It consists of two annular, double--sided Silicon strip detectors and an array of 24 position--resolving NaI(Tl) scintillation detectors. In a first experiment performed in July 2002, the setup was used to detect ???? coincidence events from the ^12C(^16O,?) ^24Mg reaction, with the aim of measuring the quadruple angular correlations and, thus, determine spins of high-lying states in ^24Mg. In this experiment, the 24 NaI-- detectors measure both energies and positions of the ?--rays emitted from the nuclear reaction. In order to accomplish that, each detector possesses two photomultiplier tubes attached to the opposite ends of a cylindrical crystal. Since the scintillation light is attenuated as it travels through the crystal, the relative light output on both sides can be used to reconstruct the position of the ? ray along the cylinder axis. This presentation focuses on the calibration and data analysis methods employed in the analysis of signals from these detectors. We tested two different hypotheses in the reconstruction of ?--ray energy and position. The first method assumes exponential light attenuation, the second a linear attenuation. We will compare the merits of both approaches. We developed software tools to automatically determine compensation for electronic gain drifts which occurred during the experiment.

Lee, Yik-Kheng; Diffenderfer, Eric; Fridmann, Joel; Wiedenhoever, Ingo

2002-10-01

337

Photon Counting Energy Dispersive Detector Arrays for X-ray Imaging  

PubMed Central

The development of an innovative detector technology for photon-counting in X-ray imaging is reported. This new generation of detectors, based on pixellated cadmium telluride (CdTe) and cadmium zinc telluride (CZT) detector arrays electrically connected to application specific integrated circuits (ASICs) for readout, will produce fast and highly efficient photon-counting and energy-dispersive X-ray imaging. There are a number of applications that can greatly benefit from these novel imagers including mammography, planar radiography, and computed tomography (CT). Systems based on this new detector technology can provide compositional analysis of tissue through spectroscopic X-ray imaging, significantly improve overall image quality, and may significantly reduce X-ray dose to the patient. A very high X-ray flux is utilized in many of these applications. For example, CT scanners can produce ~100 Mphotons/mm2/s in the unattenuated beam. High flux is required in order to collect sufficient photon statistics in the measurement of the transmitted flux (attenuated beam) during the very short time frame of a CT scan. This high count rate combined with a need for high detection efficiency requires the development of detector structures that can provide a response signal much faster than the transit time of carriers over the whole detector thickness. We have developed CdTe and CZT detector array structures which are 3 mm thick with 16×16 pixels and a 1 mm pixel pitch. These structures, in the two different implementations presented here, utilize either a small pixel effect or a drift phenomenon. An energy resolution of 4.75% at 122 keV has been obtained with a 30 ns peaking time using discrete electronics and a 57Co source. An output rate of 6×106 counts per second per individual pixel has been obtained with our ASIC readout electronics and a clinical CT X-ray tube. Additionally, the first clinical CT images, taken with several of our prototype photon-counting and energy-dispersive detector modules, are shown. PMID:19920884

Iwanczyk, Jan S.; Nygård, Einar; Meirav, Oded; Arenson, Jerry; Barber, William C.; Hartsough, Neal E.; Malakhov, Nail; Wessel, Jan C.

2009-01-01

338

Population density estimated from locations of individuals on a passive detector array  

USGS Publications Warehouse

The density of a closed population of animals occupying stable home ranges may be estimated from detections of individuals on an array of detectors, using newly developed methods for spatially explicit capture–recapture. Likelihood-based methods provide estimates for data from multi-catch traps or from devices that record presence without restricting animal movement ("proximity" detectors such as camera traps and hair snags). As originally proposed, these methods require multiple sampling intervals. We show that equally precise and unbiased estimates may be obtained from a single sampling interval, using only the spatial pattern of detections. This considerably extends the range of possible applications, and we illustrate the potential by estimating density from simulated detections of bird vocalizations on a microphone array. Acoustic detection can be defined as occurring when received signal strength exceeds a threshold. We suggest detection models for binary acoustic data, and for continuous data comprising measurements of all signals above the threshold. While binary data are often sufficient for density estimation, modeling signal strength improves precision when the microphone array is small.

Efford, Murray G.; Dawson, Deanna K.; Borchers, David L.

2009-01-01

339

Fabrication and characterization of individually addressable vertical-cavity surface-emitting laser arrays and integrated VCSEL/PIN detector arrays  

NASA Astrophysics Data System (ADS)

With the emergence of the internet, the demand for high data transmission rates in short haul area networks and fiber-to-the- desktop applications is increasing every year. Densely packed one-dimensional and two-dimensional vertical-cavity surface-emitting laser (VCSEL) arrays offer new possibilities for future short haul parallel optical links, free-space optical interconnects at the chip-to-chip, board-to-board, and on-board level. In this paper, we describe the manufacturing process of individually addressable two-dimensional VCSEL arrays, PIN detector arrays, and integrated VCSEL / PIN detector arrays. We also present measurement results of the fabricated devices and comment on the reliability.

Kasten, A. M.; Giannopoulos, A. V.; Long, C.; Chen, C.; Choquette, K. D.

2007-02-01

340

Detectivity of a UV-B photodiode  

Microsoft Academic Search

This paper reports on the transmission by a thin silver filter of the UV-B band, and on the suitability of this filter for use in combination with a silicon photodiode to make a simple, versatile detector for the UV-B band. The UV-B band, from 280 to 320 nanometers, is considered the most dangerous region of ultraviolet sunlight which reaches the

Joseph C. Larrabee; V. C. Baisley; Robert E. Huffman; Robert D. Meade; J. Joannopoulos

1994-01-01

341

Automated detection and interpretation of spectral information using cross-correlation, millilitre volumes, pneumatic nebulization sample introduction and inductively coupled plasma-atomic emission spectrometry with photodiode array detection  

NASA Astrophysics Data System (ADS)

A method for automated detection and interpretation of spectral information from ˜230 nm spectral windows, millilitre volume samples for 15 elements is presented. The basic approach involves cross-correlation of a spectral pattern obtained by running laboratory prepared multi-element `unknowns' with a reference spectral pattern obtained by running a single element standard. From the resultant cross-correlogram, it can be decided whether or not the sought-for reference spectral pattern (and the corresponding element) are present in the unknown. Spectral patterns were acquired using an inductively coupled plasma-atomic emission spectrometry (ICP-AES) system equipped with a linear, 1024-element, photo-diode array (Leco, Plasmarray). Reference spectral patterns for Al, Au, Be, Cd, Cu, Ga, Mg, Mn, Ni, Pd, Si, Sc, Y, Sr and Zn were converted to noise-free and interference-free binary software masks and, subsequently, to analogue software masks. Cross-correlation of the analogue masks with spectral patterns acquired by running multi-element unknowns is discussed, an algorithm that does not rely on fast Fourier transforms (FFT) to calculate cross-correlations is presented and a context-sensitive, colour-coded and interrogatable periodic table graphical user-interface that presents the likely composition of an unknown on the computer screen is described in detail.

Karanassios, V.; Drouin, P. J.; Spiers, G. A.

1998-08-01

342

Micro-mirror arrays for spectroscopic applications  

NASA Astrophysics Data System (ADS)

Visible and Near Infrared (NIR) spectroscopy finds use in a number of applications including security, biomedicine, military, materials science, and materials processing areas to name a few. Visible red and NIR ranges are particularly valuable for in vivo studies because photons in this range have very low potential energy and are hence usually considered noninvasive. Integrated spectrometers operating in the NIR spectral range can have high resolution and transmission, low cost, and can exhibit low noise depending on detection properties and light throughput. Optical and NIR spectrometers in this and other work have been shown to operate under normal environmental conditions (such as temperature, atmospheric gases, and humidity) and do not generally require vacuum operation. In this research, the "spectral analysis" sections of a micro-mirror based Reflective Adaptive Slit (RAS) with single InGaAs photodiode spectrometer has been studied and compared to a conventional InGaAs array detector based spectrometer. It should be noted that in both approach, either RAS with single photodiode or Conventional Array Detector (CAD) based spectrometry, the spectrometer system requires a dispersive element (prism or grating) or filter to separate the polychromatic light beam under analysis. If the system is a so called "active" system, a light source is also needed. In this work we test, model, and compare a Reflective Adaptive Slit micro-mirror based single element photodiode system to a commercial array detector based spectrometer. Within the context of the Reflective single photodiode micro-mirror Slit spectrometer, we are establishing a set of optical requirements to ideally cover a number of applications. In addition to experimental performance comparisons between the spectrometer approaches, we will report on the performance requirements and environmental issues for these NIR spectrometers.

Duncan, W. M.; Maxwell, C. J.

2014-03-01

343

DENSITY: software for analysing capture-recapture data from passive detector arrays  

USGS Publications Warehouse

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.

Efford, M.G.; Dawson, D.K.; Robbins, C.S.

2004-01-01

344

Observation of high energy atmospheric neutrinos with antarctic muon and neutrino detector array  

SciTech Connect

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.

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

345

Design and performance of blocked-impurity-band detector focal plane arrays  

NASA Astrophysics Data System (ADS)

The design, fabrication, and performance of hybrid focal-plane arrays for the long-wavelength IR region are discussed. The arrays are based on Si:As back-illuminated blocked-impurity-band (BIBIB) detectors and switched-MOSFET multiplexers to provide anomaly-free cryogenic operation. The fundamental principles of hybrid arrays and BIBIB detection are reviewed; the development of the multiplexer is described in detail; and the results of performance tests on a 500-element array are presented. Diagrams, drawings, graphs, photographs, and tables of numerical data are provided. Performance parameters include operating temperature 4-12 K, integration time from 62.5 microsec to 300 sec, source-follower gain 0.7, node capacitance 400-460 fF, rms read noise at 3-kHz bandwidth 26 microV (output) and 110 electrons (input), maximum charge capacity greater than 2 x 10 to the 6th electrons, and power dissipation (in 1 msec integration time) less than 5 microW/pixel.

Stetson, S. B.; Reynolds, D. B.; Stapelbroek, M. G.; Stermer, R. L.

1986-01-01

346

Development of a Versatile Array of Neutron Detectors at Low Energy  

NASA Astrophysics Data System (ADS)

The development of radioactive ion beams at the Holifield Radioactive Ion Beam Facility at ORNL allows the study of many neutron- and proton-rich nuclei. Proton transfer with (d,n) reactions is an excellent tool for measuring single-proton strength in neutron-rich nuclei near the Z=28 and 50 shell closures. On the proton-rich side (d,n) reactions on ^56Ni and ^25Al are relevant for nuclear astrophysics. We also propose measurements of beta decay properties in nuclei near ^78Ni and ^132Sn to determine beta decay lifetimes and branching ratios. The Versatile Array of Neutron Detectors at Low Energy (VANDLE) is a new array of plastic scintillator bars under development at ORNL. The array is highly modular allowing the configuration of the individual elements to be optimized for particular experimental requirements. We propose one configuration optimized for beta-delayed neutron emission studies and one optimized for (d,n) reactions. The scientific motivation and details of the testing and design of the array will be presented.

Matei, Catalin; Bardayan, D. W.; Blackmon, J. C.; Cizewski, J. A.; Peters, W. A.; Grzywacz, R. K.; Liddick, S. N.; Padgett, S. W.; Pain, S. D.; Sarazin, F.

2008-10-01

347

Parallel Beam Approximation for Calculation of Detection Efficiency of Crystals in PET Detector Arrays  

PubMed Central

In this work we propose a parallel beam approximation for the computation of the detection efficiency of crystals in a PET detector array. In this approximation the detection efficiency of a crystal is estimated using the distance between source and the crystal and the pre-calculated detection cross section of the crystal in a crystal array which is calculated for a uniform parallel beam of gammas. The pre-calculated detection cross sections for a few representative incident angles and gamma energies can be used to create a look-up table to be used in simulation studies or practical implementation of scatter or random correction algorithms. Utilizing the symmetries of the square crystal array, the pre-calculated look-up tables can be relatively small. The detection cross sections can be measured experimentally, calculated analytically or simulated using a Monte Carlo (MC) approach. In this work we used a MC simulation that takes into account the energy windowing, Compton scattering and factors in the “block effect”. The parallel beam approximation was validated by a separate MC simulation using point sources located at different positions around a crystal array. Experimentally measured detection efficiencies were compared with Monte Carlo simulated detection efficiencies. Results suggest that the parallel beam approximation provides an efficient and accurate way to compute the crystal detection efficiency, which can be used for estimation of random and scatter coincidences for PET data corrections.

Komarov, Sergey; Song, Tae Yong; Wu, Heyu; Tai, Yuan-Chuan

2014-01-01

348

Validation of an immunoassay method for the determination of traces of carbaryl in vegetable and fruit extracts by liquid chromatography with photodiode array and mass spectrometric detection  

Microsoft Academic Search

A competitive enzyme-linked immunosorbent assay (ELISA) method for carbaryl quantitation in crop extracts was validated by liquid chromatography (LC) with diode array detection (DAD). For this purpose, six crops (banana, carrot, green bean, orange, peach and potato) were chosen for recovery and reproducibility studies. The general sample preparation included extraction with methanol followed by liquid–liquid partitioning and clean-up on Celite–charcoal

G. S Nunes; M. P Marco; M. L Ribeiro; D Barceló

1998-01-01

349

Evaluation of a far infrared Ge:Ga multiplexed detector array  

NASA Technical Reports Server (NTRS)

The performance of a multielement Ge:Ga linear array under low-background conditions is investigated. On-focal plane switching is accomplished by MOSFET switches and the integrated charge is made available through MOSFET source followers. The tests were conducted at 106 microns and the radiation on the detectors was confined to a spectral window 1.25 microns wide using a stack of cold filters. At 4.2 K, the responsivity was measured to be nominally 584 A/W, and the NEP was 1.0 x 10 exp -16 W/sq rt Hz. A detailed description of the test setup and the procedure is presented.

Farhoomand, Jam; Mccreight, Craig

1990-01-01

350

Simulations and developments of the Low Energy Neutron detector Array LENA  

NASA Astrophysics Data System (ADS)

Prototypes of the Low Energy Neutron detector Array (LENA) have been tested and compared with detailed GEANT simulations. LENA will consist of plastic scintillation bars with the dimensions 1000×45×10 mm3. The tests have been performed with ?-ray sources and neutrons originating from the neutron-induced fission of 235U. The simulations agreed very well with the measured response and were therefore used to simulate the response to mono-energetic neutrons with different detection thresholds. LENA will be used to detect low-energy neutrons from (p,n)-type reactions with low momentum transfer foreseen at the R3B and EXL setups at FAIR, Darmstadt.

Langer, C.; Algora, A.; Couture, A.; Csatlós, M.; Gulyás, J.; Heil, M.; Krasznahorkay, A.; O'Donnell, J. M.; Plag, R.; Reifarth, R.; Stuhl, L.; Sonnabend, K.; Tornyi, T.; Tovesson, F.

2011-12-01

351

A new detector for mass spectrometry: Direct detection of low energy ions using a multi-pixel photon counter  

SciTech Connect

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.

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

352

A 2-D Array of Superconducting Magnesium Diboride (MgB2) Far-IR Thermal Detectors for Planetary Exploration  

NASA Technical Reports Server (NTRS)

A 2-D array of superconducting Magnesium Diboride(MgB2) far IR thermal detectors has been fabricated. Such an array is intended to be at the focal plane of future generation thermal imaging far-IR instruments that will investigate the outer planets and their icy moons. Fabrication and processing of the pixels of the array as well as noise characterization of architectured MgB2 thin films will be presented. Challenges and solutions for improving the performance of the array will be discussed.

Lakew, Brook

2009-01-01

353

Photodiodes for ten micrometer laser communication systems  

NASA Technical Reports Server (NTRS)

The performance is discussed of 10-micron mercury-cadmiumtelluride and lead-tin-telluride photodiodes in laser heterodyne communication systems. The dependence of detector quantum efficiency, resistance, frequency response, and signal-to-noise ratio on temperature, bias, and local oscillator power are examined. Included in the discussion is an analysis of the feasibility of high temperature operation, and ability of the detector to dissipate power to a heat sink is explored. Some aspects of direct detection response are considered and figures showing flux levels from a blackbody presented.

Cohen, S. C.

1972-01-01

354

Dark current measurement of Type-II superlattice infrared focal plane array detector  

NASA Astrophysics Data System (ADS)

We report the result of a dark current measurement of a Type-II superlattice (T2SL) infrared focal plane array (FPA), which consists of a 6 ?m cutoff T2SL detector array and the readout integration circuit (ROIC) ISC0903 of FLIR Systems. In order to measure the dark current of the FPA, we obtained images with different exposure times in a fully closed cold shield of 77 K. Using the temporal change rate of the output and considering the charge conversion efficiency of the ROIC, we obtained a dark current density with an average value of 4 × 10-5 A/cm2 at a bias of -100 mV. We also compare the result of the FPA dark current measurement with that of a test element group (TEG), which was a single pixel detector, fabricated by the same process as the FPA. The dark current density of the TEG was 3 × 10-6 A/cm2 at a bias of -100 mV, lower than that of the FPA. We discuss the discrepancy between the dark current densities of the FPA and the TEG.

Sakai, Michito; Katayama, Haruyoshi; Murooka, Junpei; Kimata, Masafumi; Iguchi, Yasuhiro

2014-06-01

355

Attenuation study for Tibet Water Cherenkov Muon Detector Array-A  

E-print Network

This work aims at online calibrating the signal attenuation of the long cable used in Tibet Water Cherenkov Muon detector array-A (Tibet MD-A) under the 37 000 m2 Tibet air shower array. Based on the waterproof connection of the PMT (R3600_06) with the signal cable, and the characters of the high voltage divider, terminal reflection method is explored and used for measuring the signal attenuation with a practical way to eliminate the contribution of the pulse baseline (pedestal). Comparison measurement between it and QDC (Charge-to-Digital Conversion) data taking method are carried out by using open-ended cables, confirming that terminal reflection method is a fast and convenient method, and suitable to online calibrate the signal attenuation for Tibet MD-A. At 26\\degree C, the measured attenuation coefficient with the 250-m cable, permanently connected to the PMT, is ~13.9%. Also, the cable frequency response is measured by using the sinusoidal signals, which could be used to study the time dispersion of the real signal produced with Tibet MD-A detector via Fourier analysis.

Quanbu Gou; Yiqing Guo; Cheng Liu; Xiangli Qian; Zhengtao Hou

2011-03-22

356

Attenuation study for Tibet Water Cherenkov Muon Detector Array-A  

E-print Network

The attenuation study of the long cable used in Tibet Water Cherenkov Muon Detector Array-A, called Tibet MD-A (one of 12 Tibet MD detectors), under the 37000 m2 Tibet air shower array, is reported. The cable frequency response is measured by using the sinusoidal signals, with which the influence of the cable on the pulse rise time is obtained. For the reason that the commercial 20 inch PMT (R3600_06) has a waterproof connection with the signal cable, one end of the signal cable is permanently connected to the PMT. Terminal reflection method is tested and used for measuring the signal attenuation. During the measurement, a practical way to eliminate the uncertainty caused by the baseline of the signal is achieved. To check the terminal reflection method, comparison measurement between it and QDC data taking method are carried out by using open-ended cables. The confirmed terminal reflection method is a fast and convenient method being suitable to online measure the signal attenuation for Tibet MD-A. The measu...

Gou, Quanbu; Liu, Cheng; Feng, Zhaoyang; Qian, Xiangli; Hou, Zhengtao

2011-01-01

357

CMOS detector arrays in a virtual 10-kilopixel camera for coherent terahertz real-time imaging.  

PubMed

We demonstrate the principle applicability of antenna-coupled complementary metal oxide semiconductor (CMOS) field-effect transistor arrays as cameras for real-time coherent imaging at 591.4 GHz. By scanning a few detectors across the image plane, we synthesize a focal-plane array of 100×100 pixels with an active area of 20×20 mm2, which is applied to imaging in transmission and reflection geometries. Individual detector pixels exhibit a voltage conversion loss of 24 dB and a noise figure of 41 dB for 16 ?W of the local oscillator (LO) drive. For object illumination, we use a radio-frequency (RF) source with 432 ?W at 590 GHz. Coherent detection is realized by quasioptical superposition of the image and the LO beam with 247 ?W. At an effective frame rate of 17 Hz, we achieve a maximum dynamic range of 30 dB in the center of the image and more than 20 dB within a disk of 18 mm diameter. The system has been used for surface reconstruction resolving a height difference in the ?m range. PMID:22344098

Boppel, Sebastian; Lisauskas, Alvydas; Max, Alexander; Krozer, Viktor; Roskos, Hartmut G

2012-02-15

358

Far infrared thermal detectors for laser radiometry using a carbon nanotube array  

SciTech Connect

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 {mu}m, 150 {mu}m, and 1.5 mm were evaluated with respect to reflectance at a laser wavelength of 394 {mu}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.

Lehman, John H.; Lee, Bob; Grossman, Erich N.

2011-07-20

359

Performance analysis of MIMO FSO systems with radial array beams and finite sized detectors  

NASA Astrophysics Data System (ADS)

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.

Gökçe, Muhsin C.; Kamac?o?lu, Canan; Uysal, Murat; Baykal, Yahya

2014-10-01

360

Performance assessment of a 2D array of plastic scintillation detectors for IMRT quality assurance.  

PubMed

The purposes of this work are to assess the performance of a 2D plastic scintillation detectors array prototype for quality assurance in intensity-modulated radiation therapy (IMRT) and to determine its sensitivity and specificity to positioning errors of one multileaf collimator (MLC) leaf and one MLC leaf bank by applying the principles of signal detection theory. Ten treatment plans (step-and-shoot delivery) and one volumetric modulated arc therapy plan were measured and compared to calculations from two treatment-planning systems (TPSs) and to radiochromic films. The averages gamma passing rates per beam found for the step-and-shoot plans were 95.8% for the criteria (3%, 2 mm), 97.8% for the criteria (4%, 2 mm), and 98.1% for the criteria (3%, 3 mm) when measurements were compared to TPS calculations. The receiver operating characteristic curves for the one leaf errors and one leaf bank errors were determined from simulations (theoretical upper limits) and measurements. This work concludes that arrays of plastic scintillation detectors could be used for IMRT quality assurance in clinics. The use of signal detection theory could improve the quality of dosimetric verifications in radiation therapy by providing optimal discrimination criteria for the detection of different classes of errors. PMID:23756497

Guillot, Mathieu; Gingras, Luc; Archambault, Louis; Beddar, Sam; Beaulieu, Luc

2013-07-01

361

Dosimetric performance and array assessment of plastic scintillation detectors for stereotactic radiosurgery quality assurance  

SciTech Connect

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.

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

362

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)

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.

Safren, H. G.

1987-01-01

363

Superconducting-nanowire single-photon-detector linear array Qingyuan Zhao, Adam McCaughan, Francesco Bellei, Faraz Najafi, Domenico De Fazio, Andrew Dane, Yachin  

E-print Network

.1063/1.2221516 Fiber-coupled single-photon detectors based on NbN superconducting nanostructures for practical quantum-dimensional array of superconducting-nanowire single- photon detectors, integrated with on-chip inductors

Berggren, Karl K.

364

Uncooled Thermopile Infrared Detector Linear Arrays with Detectivity Greater Than 10(super script9) cmHZ(super script 1/2)/W  

NASA Technical Reports Server (NTRS)

We have fabricated 63-element linear arrays of micromachined thermopile infrared detectors on silicon substrates. Each detector consists of a suspended silicon nitride membrane with 11 thermocouples of sputtered Bi-Te and Bi-Sb-Te films.

Foote, Marc C.; Jones, Eric W.; Caillat, Thierry

1997-01-01

365

ZnO homojunction photodiodes based on Sb-doped p-type nanowire array and n-type film for ultraviolet detection  

NASA Astrophysics Data System (ADS)

ZnO p-n homojunctions based on Sb-doped p-type nanowire array and n-type film were grown by combining chemical vapor deposition (for nanowires) with molecular-beam epitaxy (for film). Indium tin oxide and Ti/Au were used as contacts to the ZnO nanowires and film, respectively. Characteristics of field-effect transistors using ZnO nanowires as channels indicate p-type conductivity of the nanowires. Electron beam induced current profiling confirmed the existence of ZnO p-n homojunction. Rectifying I-V characteristic showed a turn-on voltage of around 3 V. Very good response to ultraviolet light illumination was observed from photocurrent measurements.

Wang, Guoping; Chu, Sheng; Zhan, Ning; Lin, Yuqing; Chernyak, Leonid; Liu, Jianlin

2011-01-01

366

ZnO homojunction photodiodes based on Sb-doped p-type nanowire array and n-type film for ultraviolet detection  

SciTech Connect

ZnO p-n homojunctions based on Sb-doped p-type nanowire array and n-type film were grown by combining chemical vapor deposition (for nanowires) with molecular-beam epitaxy (for film). Indium tin oxide and Ti/Au were used as contacts to the ZnO nanowires and film, respectively. Characteristics of field-effect transistors using ZnO nanowires as channels indicate p-type conductivity of the nanowires. Electron beam induced current profiling confirmed the existence of ZnO p-n homojunction. Rectifying I-V characteristic showed a turn-on voltage of around 3 V. Very good response to ultraviolet light illumination was observed from photocurrent measurements.

Wang Guoping; Chu Sheng; Zhan Ning; Liu Jianlin [Department of Electrical Engineering, Quantum Structures Laboratory, University of California at Riverside, Riverside, California 92521 (United States); Lin Yuqing; Chernyak, Leonid [Department of Physics, University of Central Florida, Orlando, Florida 32816-2385 (United States)

2011-01-24

367

Results of a two-color detector array in bulk mercury cadmium telluride  

NASA Astrophysics Data System (ADS)

It is well established that for a reduction of clutter and enhancement of desired features/contrast, one will require the use of multispectral focal plane arrays. These arrays will be highly beneficial for a variety of applications such as missile warning and guidance, precision strike, overhead surveillance, target detection, recognition, acquisition and tracking, thermal imaging, navigational aids and night vision, etc. Currently a common approach for the fabrication of multispectral arrays is via epitaxial deposition of layers of mercury cadmium telluride of different compositions on top of each other. Here we start with a bulk wafer of mercury cadmium telluride with a composition that is suitable for the detection of one of the required wavelengths. Next, the compositions suitable for the detection of other wavelengths are achieved via selective deposition and diffusion of CdTe or HgTe. Thus the individual detector elements corresponding to the different colors lie in the same plane and not on top of each other. These can now be interfaced to simple multiplexers, rather than those with switching capabilities. Additional advantages include improvements in cost and producibility.

Jindal, Bal K.

1994-07-01

368

LENDA: A low energy neutron detector array for experiments with radioactive beams in inverse kinematics  

NASA Astrophysics Data System (ADS)

The Low Energy Neutron Detector Array (LENDA) is a neutron time-of-flight (TOF) spectrometer developed at the National Superconducting Cyclotron Laboratory (NSCL) for use in inverse kinematics experiments with rare isotope beams. Its design has been motivated by the need to study the spin-isospin response of unstable nuclei using (p,n) charge-exchange reactions at intermediate energies (>100 MeV/u). It can be used, however, for any reaction study that involves emission of low energy neutrons (150 keV to 10 MeV). The array consists of 24 plastic scintillator bars and is capable of registering the recoiling neutron energy and angle with high detection efficiency. The neutron energy is determined by the time-of-flight technique, while the position of interaction is deduced using the timing and energy information from the two photomultipliers of each bar. A simple test setup utilizing radioactive sources has been used to characterize the array. Results of test measurements are compared with simulations. A neutron energy threshold of <150 keV, an intrinsic time (position) resolution of ˜ 400 ps (˜ 6 cm) and an efficiency >20% for neutrons below 4 MeV have been obtained.

Perdikakis, G.; Sasano, M.; Austin, Sam M.; Bazin, D.; Caesar, C.; Cannon, S.; Deaven, J. M.; Doster, H. J.; Guess, C. J.; Hitt, G. W.; Marks, J.; Meharchand, R.; Nguyen, D. T.; Peterman, D.; Prinke, A.; Scott, M.; Shimbara, Y.; Thorne, K.; Valdez, L.; Zegers, R. G. T.

2012-09-01

369

A 2×2 array of EMCCD-based solid state x-ray detectors.  

PubMed

We have designed and developed a new solid-state x-ray imaging system that consists of a 2×2 array of electron multiplying charge coupled devices (EMCCDs). This system is intended for fluoroscopic and angiographic medical imaging. The key components are the four 1024 × 1024 pixel EMCCDs with a pixel size of 13 × 13 µm(2). Each EMCCD is bonded to a fiber optic plate (FOP), and optically coupled to a 350 µm thick micro-columnar CsI(TI) scintillator via a 3.22?1 fiber optic taper (FOT). The detector provides x-ray images of 9 line pairs/mm resolution at 15 frames/sec and real-time live video at 30 frames/sec with binning at a lower resolution, independent of the electronic gain applied to the EMCCD. The total field of view (FOV) of the array is 8.45 cm × 8.45 cm. The system is designed to also provide the ability to do region-of- interest imaging (ROI) by selectively enabling individual modules of the array. PMID:23367292

Sharma, P; Swetadri Vasan, S N; Titus, A H; Cartwright, A N; Bednarek, D R; Rudin, S

2012-01-01

370

[Research on the neas infrared focal plane array detector imaging technology used in the laser warning].  

PubMed

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

Wang, Zhi-Bin; Huang, Yan-Fei; Wang, Yao-Li; Zhang, Rui; Wang, Yan-Chao

2014-04-01

371

Small-angle solution scattering using the mixed-mode pixel array detector  

PubMed Central

Solution small-angle X-ray scattering (SAXS) measurements were obtained using a 128 × 128 pixel X-ray mixed-mode pixel array detector (MMPAD) with an 860?µs readout time. The MMPAD offers advantages for SAXS experiments: a pixel full-well of >2 × 107 10?keV X-rays, a maximum flux rate of 108?X-rays pixel?1 s?1, and a sub-pixel point-spread function. Data from the MMPAD were quantitatively compared with data from a charge-coupled device (CCD) fiber-optically coupled to a phosphor screen. MMPAD solution SAXS data from lysozyme solutions were of equal or better quality than data captured by the CCD. The read-noise (normalized by pixel area) of the MMPAD was less than that of the CCD by an average factor of 3.0. Short sample-to-detector distances were required owing to the small MMPAD area (19.2?mm × 19.2?mm), and were revealed to be advantageous with respect to detector read-noise. As predicted by the Shannon sampling theory and confirmed by the acquisition of lysozyme solution SAXS curves, the MMPAD at short distances is capable of sufficiently sampling a solution SAXS curve for protein shape analysis. The readout speed of the MMPAD was demonstrated by continuously monitoring lysozyme sample evolution as radiation damage accumulated. These experiments prove that a small suitably configured MMPAD is appropriate for time-resolved solution scattering measurements. PMID:21335900

Koerner, Lucas J.; Gillilan, Richard E.; Green, Katherine S.; Wang, Suntao; Gruner, Sol M.

2011-01-01

372

Development of a unit cell for a Ge:Ga detector array  

NASA Technical Reports Server (NTRS)

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.

1988-01-01

373

Quantum-dot based avalanche photodiodes for mid-infrared Majeed M. Hayat a  

E-print Network

Quantum-dot based avalanche photodiodes for mid-infrared sensing Majeed M. Hayat a , Oh-Hyun Kwon b ABSTRACT A mid-infrared sensor is proposed in which an intersubband quantum-dot (QD) detector is integrated temperatures. Keywords: Quantum dots, avalanche photodiodes, infrared, sensors, mid-wave infrared, avalanche

Hayat, Majeed M.

374

SiPM detectors for the ASTRI project in the framework of the Cherenkov Telescope Array  

NASA Astrophysics Data System (ADS)

The Cherenkov Telescope Array (CTA) is a worldwide new generation project aimed at realizing an array of a hundred ground based gamma-ray telescopes. ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) is the Italian project whose primary target is the development of an end-to-end prototype, named ASTRI SST-2M, of the CTA small size class of telescopes devoted to investigation of the highest energy region, from 1 to 100 TeV. Next target is the implementation of an ASTRI/CTA mini-array based on seven identical telescopes. Silicon Photo-Multipliers (SiPMs) are the semiconductor photosensor devices designated to constitute the camera detection system at the focal plane of the ASTRI telescopes. SiPM photosensors are suitable for the detection of the Cherenkov flashes, since they are very fast and sensitive to the light in the 300-700nm wavelength spectrum. Their drawbacks compared to the traditional photomultiplier tubes are high dark count rates, after-pulsing and optical cross-talk contributions, and intrinsic gains strongly dependent on temperature. Nonetheless, for a single pixel, the dark count rate is well below the Night Sky Background, the effects of cross-talk and afterpulses are typically lower than 20%, and the gain can be kept stable against temperature variations by means of adequate bias voltage compensation strategies. This work presents and discusses some experimental results from a large set of measurements performed on the SiPM sensors to be used for the ASTRI SST-2M prototype camera and on recently developed detectors demonstrating outstanding performance for the future evolution of the project in the ASTRI/CTA mini-array.

Billotta, Sergio; Marano, Davide; Bonanno, Giovanni; Belluso, Massimiliano; Grillo, Alessandro; Garozzo, Salvatore; Romeo, Giuseppe; Timpanaro, Maria Cristina; Maccarone, Maria Concetta C.; Catalano, Osvaldo; La Rosa, Giovanni; Sottile, Giuseppe; Impiombato, Domenico; Gargano, Carmelo; Giarrusso, Salavtore

2014-07-01

375

Simultaneous determination of phenolic acids and flavonoids in rice using solid-phase extraction and RP-HPLC with photodiode array detection.  

PubMed

An analytical method based on an optimized solid-phase extraction procedure and followed by high-performance liquid chromatography (HPLC) separation with diode array detection was developed and validated for the simultaneous determination of phenolic acids (gallic, protocatechuic, 4-hydroxy-benzoic, vanillic, caffeic, syringic, p-coumaric, ferulic, sinapic, and cinnamic acids), flavanols (catechin and epicatechin), flavonols (myricetin, quercetin, kaempferol, quercetin-3-O-glucoside, hyperoside, and rutin), flavones (luteolin and apigenin) and flavanones (naringenin and hesperidin) in rice flour (Oryza sativa L.). Chromatographic separation was carried out on a PerfectSil Target ODS-3 (250 mm × 4.6 mm, 3 ?m) column at temperature 25°C using a mobile phase, consisting of 0.5% (v/v) acetic acid in water, methanol, and acetonitrile at a flow rate 1 mL min(-1) , under gradient elution conditions. Application of optimum extraction conditions, elaborated on both Lichrolut C(18) and Oasis HLB cartridges, have led to extraction of phenolic acids and flavonoids from rice flour with mean recoveries 84.3-113.0%. The developed method was validated in terms of linearity, accuracy, precision, stability, and sensitivity. Repeatability (n = 5) and inter-day precision (n = 4) revealed relative standard deviation (RSD) <13%. The optimized method was successfully applied to the analysis of phenolic acids and flavonoids in pigmented (red and black rice) and non-pigmented rice (brown rice) samples. PMID:22761138

Irakli, Maria N; Samanidou, Victoria F; Biliaderis, Costas G; Papadoyannis, Ioannis N

2012-07-01

376

Coherent summation of spatially distorted laser Doppler signals by using a two-dimensional heterodyne detector array  

NASA Technical Reports Server (NTRS)

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.

Chan, Kin P.; Killinger, Dennis K.

1992-01-01

377

X-ray micro-CT with a displaced detector array: application to helical cone-beam reconstruction.  

PubMed

In x-ray micro-CT applications, it is useful to increase the field of view by offsetting a two-dimensional (2D) detector array. In this technical note, we briefly review the methods for image reconstruction with an asymmetric 2D detector array, elaborate on the use of an associated weighting scheme in the case of helical/spiral cone-beam scanning, and perform a series of numerical tests to demonstrate helical cone-beam image reconstruction with such an arrangement. PMID:14596314

Liu, Vinson; Lariviere, Nicholas R; Wang, Ge

2003-10-01

378

Exploration of the metrological performance of a gas detector based on an array of unspecific infrared filters  

Microsoft Academic Search

The feasibility of a non-dispersive infrared (NDIR) gas detection system based on an array on non-specific detectors is studied in this work. The measurement system, that is intended to be low cost and of reduced dimension, is aimed to the simultaneous quantitative detection of different gases with IR absorption bands in the region of the 1000–4000cm?1. The detector is a

R. Rubio; J. Santander; J. Fonollosa; L. Fonseca; I. Gràcia; C. Cané; M. Moreno; S. Marco

2006-01-01

379

Infrared Detector Activities at NASA Langley Research Center  

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

380

An Asic for High-Speed and High-Resolution Decoding of Multi-Anode Microchannel Array Detectors  

NASA Astrophysics Data System (ADS)

The Multi-Anode Microchannel Array (MAMA) is a microchannel plate-based photon-counting detector with applications in ground-based and space-based astronomy. The detector requires a digital decoder to determine the position of each photon event, and the decoding algorithm that associates a given event with the appropriate pixel is determined by the geometry of the detector's anode array. An Application Specific Integrated Circuit (ASIC) version of a MAMA decoder, suitable for both ground-based and space-based applications, has been designed, fabricated and tested successfully. The design was fabricated in commercial 1.5 micron CMOS gate array technology, and the chip is smaller, faster, incorporates more options and uses less power than comparable discrete component decoders. The chip has performed well in preliminary radiation exposure tests and incorporates a new high resolution decoding algorithm that has the potential to double the detector's spatial resolution. The performance of a new high resolution algorithm has been demonstrated. The algorithm does not degrade the pulse-pair resolution of the detector; moreover, it requires no modifications to the detector tube. Besides improving image quality, high resolution decoding has the potential to lower power consumption and increase the detector signal-to-noise ratio. In addition, high resolution decoding allows the use of smaller telescopes while still preserving detector resolution, thereby decreasing satellite payload size and weight. Detector response measurements demonstrate that high resolution decoding yields at least a 60% enhancement in spatial resolution with a 25 micron MAMA detector. Detector response models which assume a Gaussian pixel response function for both low and high resolution pixels have been shown to match the actual measured detector response to within 9%. High resolution decoding is robust; variations in detector operating parameters produced at most a 6% difference in spatial resolution. Measurements of detector response indicate that the spatial resolution achieved by the high resolution decoding algorithm depends primarily on the microchannel plate pore resolution. Other parameters were found to have only second order effects on the spatial resolution. Detector responses of both the low resolution decoding and high resolution decoding algorithms display excellent temporal stability.

Kasle, David Benjamin

1992-01-01

381

Nuclear Structure of Radioactive Neutron-Rich Nuclei with 4pi Detector Arrays  

SciTech Connect

In-beam studies of {gamma}-ray spectroscopy of radioactive neutron-rich nuclei using the 4{pi} TIGRESS array at TRIUMF requires a ''tag'' to improve the selectivity of the detected {gamma} rays in the high {gamma}-ray background produced by radioactive beams and the need for Doppler-shift correction. We propose development of two types of large solid angle auxiliary charged particle detectors to be used in conjunction with TRIGRESS in order to provide the required tag. The initial phase of detector development will focus on research involving light-mass radioactive beams with Z {le} 20. Gas avalanche detectors, such as CHICO, are not the ideal detector for lighter ions. Therefore, a new detector system, called Bambino, is being developed that is based on commercially available CD type position-sensitive silicon detectors. Three CD-S2 detectors, with a thickness of 140 {micro}m, have been ordered from Micron Semiconductor Ltd. A split spherical target chamber will be built in Rochester to accommodate two of those CD detectors in both forward and backward directions. These detectors will be placed 3 cm from the target, providing an angular coverage from 20.1{sup o} to 49.4{sup o} for the forward hemisphere and from 130.6{sup o} to 159.9{sup o} for the backward hemisphere. The detectors will us ten 8-channels preamplifiers, from Swan Research, that will be mechanically mounted on both the entrance and exit beam pipes. The work on both the internal and external cables connecting the detectors to the preamplifiers, vacuum feedthrough etc. is in progress. In addition, a vacuum chamber has been ordered from Kurt J. Lesker Company for testing these detectors. Bambino should be ready by the spring 2006. The second phase will involve the development of a next generation CHICO-like gas avalanche detector for experiments involving heavier radioactive beams. CHICO, a highly segmented parallel-plate avalanche counter, has proven to be very successful when used in conjunction with Gammasphere [1-2]. It has an angular coverage of 2.8{pi} sr and an angular resolution of 1{sup o} in {theta} and 4.6{sup o} in {phi} in addition to a time resolution of 500 ps. The proposed new avalanche detector will have an improved position resolution that matches the (2 mm) achieved by TIGRESS. This longer-term detector development project is predicated on future funding and we actively seek collaborators. Such a detector system, used in conjunction with a thin target, allows the detection of both scattered and recoiling nuclei in kinematic coincidence providing a unique tag for the detected {gamma} rays and at the same time providing sufficient information for the proper Doppler-shift corrections. This detector system can accommodate many types of experiments involving (quasi) two-body kinematics, such as Coulomb excitation [2-7], few-nucleon transfer reactions [8-10], deep-inelastic reactions [11-16], and spontaneous fissions [1] or fusion-fission reactions [17-20] we have carried out in the past. The initial phase of proposed experiments will be to study, by Coulomb excitation, the issue of the ''island of inversion'' for the Mg isotopes in the N {approx} 20 region. The B(E2) values for the first 2{sup +} states of {sup 30,32,34}Mg have been measured using intermediate-energy Coulomb excitation at projectile fragmentation facilities. The B(E2) value for {sup 30}Mg also was measured recently via conventional Coulomb excitation at the CERN REX-ISOLDE facility. The spread in measured B(E2)'s of up to a factor of two is insufficient to distinguish among various shell model predictions. Obviously, more precise measurements are necessary to ascertain how well the shell model can predict the properties of neutron-rich nuclei. An accuracy about 5% for the measured B(E2) can be achieved assuming a three-day beam time with an intensity about 3 x 10{sup 4} p/s of {sup 32}Mg on a 3 mg/cm{sup 2} {sup 208}Pb target at E{sub lab} = 115 MeV. A measure of the shape or the static quadrupole moment of this nucleus, in addition to the B(E2) value, would be possible if the

Wu, C Y; Becker, J A; Cline, D

2005-05-10

382

Progress in the use of avalanche photodiodes for readout for calorimeters  

SciTech Connect

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.

Fenker, H.; Morgan, K.; Regan, T.

1991-09-01

383

Optimising the signal-to-noise ratio in measurement of photon pairs with detector arrays  

E-print Network

To evidence multimode spatial entanglement of spontaneous down-conversion, detector arrays allow a full field measurement, without any a priori selection of the paired photons. We show by comparing results of the recent literature that electron-multiplying CCD (EMCCD) cameras allow, in the present state of technology, the detection of quantum correlations with the best signal-to-noise ratio (SNR), while intensified CCD (ICCD) cameras allow at best to identify pairs. The SNR appears to be proportional to the square root of the number of coherence cells in each image, or Schmidt number. Then, corrected estimates are derived for extended coherence cells and not very low and not space-stationary photon fluxes. Finally, experimental measurements of the SNR confirm our model.

Eric Lantz; Paul-Antoine Moreau; Fabrice Devaux

2014-07-09

384

Performance of multiplexed Ge:Ga detector arrays in the far infrared  

NASA Technical Reports Server (NTRS)

The performance of two multi-element, multiplexed Ge:Ga linear arrays under low-background conditions was investigated. The on-focal switching is accomplished by MOSFET switches, and the integrated charge is made available through MOSFET source followers. The tests were conducted at 106 microns, and the radiation on the detectors was confined to a spectral window 1.25 microns wide using a stack of cold filters. At 4.2 K, the highest responsivity was 584 A/W, the noise equivalent power was 1.0 x 10(exp -16) W/square root of Hz, and the read noise was 6100 electrons/sample. A detailed description of the test setup and procedure is presented.

Farhoomand, Jam; Mccreight, Craig

1990-01-01

385

?-delayed neutron precursors with the Versatile Array of Neutron Detectors at Low Energies (VANDLE)  

NASA Astrophysics Data System (ADS)

The production of radioactive ion beams of nuclei away from stability in new facilities such as Lerribs offers the opportunity of studying the properties of nuclear matter dominated by large proton-neutron imbalances, resulting in new effects like shell evolution and new magic numbers. The ?-decay is an excellent probe of nuclear structure, a selective and well understood mechanism. However, for exotic nuclei, a significant fraction of the ?-strength will populate neutron unbound states. The proposed VANDLE will consist of an array of 164 plastic scintillator bars to measure the neutron energy using time of flight technique. The expected large neutron energy dynamic range and its modular design will give the flexibility necessary to use the detector in experiments with requirements as different as ?-decay of neutron rich elements to (d,n) reaction experiments. Results of the proof-of-principle measurement of the ^89Br ?-delayed neutron emission will be presented.

Madurga, M.; Paulauskas, S.; Grzywacz, R.; Padgett, S.; Bardayan, D.; Blackmon, J.; Cizewski, J.; O'Malley, P.; Liddick, S.; Peters, W. A.; Raiola, F.; Sarazin, F.

2010-11-01

386

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

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

Langer, Swen; Lodge, John K

2014-06-01

387

New insights from studies of spontaneous fission with large detector arrays  

NASA Astrophysics Data System (ADS)

The new insights into a) the rapidly varying structures of neutron-rich nuclei up to spins as high as 20 + and 19 -, b) the spontaneous fission process itself, and c) modes of cluster radioactivity that have come out of studies of spontaneous fission of 242Pu, 248Cm and 252Cf with large detector arrays are presented. The studies include ?-?-? coincidences with the second generation (14-20 Compton-suppressed Ge arrays) and new, third generation (35-45 Compton-suppressed Ge arrays, Gammasphere and Eurogam) gamma-ray detector arrays. The neutron-rich nuclei observed span the full range from superdeformed ( ?2 ? 0.4) double-magic ground states to spherical double-magic nuclei and competing shapes in between. New structure insights include the following: New regions of identical ground state bands to spins of 10 + to 16 + were discovered; one at the sudden onset of large deformation at N=60,62 in both even- and odd-A 98-101Sr, one at midshell N = 64,66 in 108,110Ru, one for N = 88-90 144,146Ba, one for N = 92-94 152,154Nd, and at high spin in 156Nd and also in excited bands in these regions. New shape coexisting structures in both even- and odd-A for A = 96-102 Sr and Zr nuclei are found. Evidence is found in both even-even and odd-A nuclei for a new region of octupole deformation around Z = 56 and N = 86-88. Rapid changes in moments of inertia are observed with changes in Z and N of two units with sudden changes in the moments of inertia associated with band crossings. The levels in many neutron-rich nuclei are observed for the first time. Earlier, plunger studies yielded lifetimes of low spin states and recently the Doppler Shift Line Shape Analysis yielded lifetimes of high spin states. For the first time, direct measurements of yields and neutron multiplicities have been made for five correlated pairs of fission fragments of Sr?Nd, Zr?Ce, Mo?Ba, Ru?Xe and Pd?Te nuclei. Neutron multiplicities from 0-10 v emission (10v for the first time) were observed in Mo?Ba correlated pairs with the 0 and 7-10 neutron-emission yields enhanced compared to gross yields for all fragments. The Mo?Ba data provide evidence for two different fission modes. By unfolding the observed Mo?Ba yields, the masses and excitation energies and mass distributions at scission were extracted. These data revealed a new mode involving the high neutron multiplicities that occurs essentially through one pair, 108Mo? 144Ba, 107Mo? 145Ba, or 106Mo? 146Ba or some combination where the 144Ba, 145Ba and/or 146Ba at scission are hyperdeformed with a long-to-short axis ratio of 3:1. The zero-neutron emission channels provide new examples of the cold rearrangements of nucleons in a new type of cluster radioactivity. The cluster radioactivity model predicted the observed enhancements of the zero-neutron channels for odd-A-odd-A nuclei as well as the observed fine structure, that is, the spin distributions of the two fragments. The measurements of intensities and ?-?-? coincidences in SF with large detector arrays open a new era in the determination of previously inaccessible properties of neutron-rich nuclei and the fission process.

Hamilton, J. H.; Ramayya, A. V.; Zhu, S. J.; Ter-Akopian, G. M.; Oganessian, Yu. Ts.; Cole, J. D.; Rasmussen, J. O.; Stoyer, M. A.

388

Reducing the Read Noise of H2RG Detector Arrays by more Efficient use of Reference Signals  

NASA Technical Reports Server (NTRS)

We present a process for characterizing the correlation properties of the noise in large two-dimensional detector arrays, and describe an efficient process for its removal. In the case of the 2k x 2k HAWAII-2RG detectors (H2RG) detectors from Teledyne which are being used on the Near Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope (JWST), we find that we can reduce the read noise by thirty percent. Noise on large spatial scales is dramatically reduced. With this relatively simple process, we provide a performance improvement that is equivalent to a significant increase in telescope collecting area for high resolution spectroscopy with NIRSpec.

Rauscher, Bernard J.; Arendt, Richard G.; Fixen, D. J.; Lindler, Don; Loose, Markus; Moseley, S. H.; Wilson, D. V.

2011-01-01

389

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

SciTech Connect

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

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

1998-11-07

390

An uncooled thermal-array-based detector as an advanced security sensor  

NASA Astrophysics Data System (ADS)

A 16x16 un-cooled thermal array based detector (ABD) offers the prospect of a new generation of security sensors, with high false alarm rejection and the ability to detect, track and count the number of intruders. The IRISYS array provides the ability not simply to detect an intruder, but by tracking them as a true moving target discriminate between real and false alarm sources. Target processing is carried out within the sensor allowing the position and size of each target within the field of view to be generated. The location and size for each target is output as a low bandwidth data message suitable for transmission over alarm signalling networks. A central security management system or alarm receiving centre display would provide an operator with an intruder count per room, a pseudo 'visual' display of targets and locations, show target vectors on a graphical display and track targets from room to room, allowing an appropriate response to be initiated. Taking the same concepts into external detection, should allow discrimination of humans versus animals or vermin and afford a high level of reasoning to reject environmentally generated false alarms. In external detection applications using the ABD as a trigger for CCTV, intruder location data would be used to steer and zoom a PTZ camera to achieve an identification view. As auto tracking features are added to the latest dome cameras the ABD's ability to track and output simultaneous data from multiple targets will steer a camera between several intruders.

Rimmer, Andrew N.

2004-09-01

391

ARIANNA: A radio detector array for cosmic neutrinos on the Ross Ice Shelf  

E-print Network

ARIANNA (The Antarctic Ross Ice Shelf Antenna Neutrino Array) is a proposed 100 km^3 detector for ultra-high energy (above 10^17 eV) astrophysical neutrinos. It will study the origins of ultra-high energy cosmic rays by searching for the neutrinos produced when these cosmic rays interact with the cosmic microwave background. Over 900 independently operating stations will detect the coherent radio Cherenkov emission produced when astrophysical neutrinos with energy above 10^17 eV interact in the Antarctic Ross Ice Shelf. Each station will use 8 log periodic dipole antennas to look for short RF pulses, with the most important frequencies between 80 MHz and 1 GHz. By measuring the pulse polarization and frequency spectrum, the neutrino arrival direction can be determined. In one year of operation, the full array should observe a clear GZK neutrino signal, with different models predicting between 3 and 51 events, depending on the nuclear composition of the cosmic-rays and on the cosmic evolution of their sources.

Spencer R. Klein; for the ARIANNA Collaboration

2012-07-16

392

Characterization and Efficiency of the Versatile Array of Neutron Detectors at Low Energy (VANDLE)  

NASA Astrophysics Data System (ADS)

The Versatile Array of Neutron Detectors at Low Energy (VANDLE) is a new array of plastic scintillator bars being developed at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory (ORNL). The modular design enables optimization of different configurations for particular experiments, such as (d,n) and beta-delayed neutron-decay experiments, with rare ion beams. Twenty prototype modules, of two different sizes, have been put together and characterized for dynamic range and scintillator attenuation. Proof-of-principle experiments have been performed for both beta-delayed neutron-decay and (d,n) reactions. In addition, we plan to measure the absolute efficiency of a few modules using a calibrated ^27Al(d,n) reaction at the Edwards Accelerator Laboratory at Ohio University. We also have access to a sealed ^252Cf source to measure relative efficiencies and for use with experiment setup design. Results from the characterization and efficiency tests of the modules and preliminary results from the proof-of-principle experiments will be presented.

Peters, William; Matei, C.; Spassova, I.; Bardayan, D. W.; Blackmon, J. C.; Cizewski, J. A.; O'Malley, P. D.; Manning, B.; Merino, E.; Massey, T.; Brune, C.; Grzywacz, R. K.; Maduga, M.; Paulauskas, S.; Sarazin, F.; Raiola, F.; Walter, D.

2010-11-01

393

MOCVD growth and characterization of ZnO nanowire arrays for advanced ultraviolet detectors  

NASA Astrophysics Data System (ADS)

Zinc oxide (ZnO) provides a unique wide bandgap biocompatible material system exhibiting both semiconducting and piezoelectric properties, and is a versatile functional material that has a diverse group of growth morphologies. 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 (NWs) and nanorods using a metal organic chemical vapor deposition (MOCVD) growth process on Si(111), SiO2, and sapphire substrates. The structural and optical properties of the grown vertically aligned ZnO nanostructure arrays were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL) measurements. The unique diffraction pattern for ZnO(002) concurred with the SEM inspection indicating vertical orientation of the NWs and nanorods. UV detectors based on ZnO NWs offer high UV sensitivity and low visible sensitivity for applications such as missile plume detection and threat warning. An analytical model that can predict sensor performance with and without gain for a desired UV band of interest has also been developed that has the potential for substantial improvements in sensor performance and reduction in size for a variety of threat warning applications. In addition, testing and characterization of photomultiplier tubes (PMTs) exposed to eight individual UV LEDs having peak wavelengths ranging from 248 nm to 370 nm has been performed to provide a relative UV detection performance benchmark. Compared to PMTs, the NW arrays are expected to exhibit low noise, extended lifetimes, high quantum efficiency, and very low power requirements.

Rivera, Abdiel; Zeller, John; Manzur, Tariq; Sood, Ashok; Anwar, Mehdi

2012-10-01

394

30TH INTERNATIONAL COSMIC RAY CONFERENCE Calibration and monitoring of the air fluorescence detector for the Telescope Array  

E-print Network

detector for the Telescope Array experiment H. TOKUNO1 , R. AZUMA2 , M. FUKUSHIMA1 , Y. HIGASHIDE3 , N-8582, Japan 2 Department of Physics, Tokyo Institute of Technology, Meguro, Tokyo, 152-8551, Japan 3 Faculty of Engineering, Musashi Institute of Technology, Setagaya, Tokyo, 158-8558, Japan 4 Department of Physics

395

Separation and Identification of Phenolic Acids from Some Species of the Asteraceae Family Using HPLC with a Diode Array Detector  

Microsoft Academic Search

The qualitative and quantitative analysis of phenolic acids was carried out using methods of HPLC with the diode array detector (DAD). The quantitative analysis of chosen phenolic acids was carried out using the Multicomponent Analysis method (MCA). Solid-phase extraction was applied for the purification of crude extract from aerial part of three species of fam. Asteraceae (Chrysanthemum maximum Ram.(DC), Chrysanthemum

W. Markowski; L. K. Czapi?ska; A. J. Józefczyk; K. Glowniak

1998-01-01

396

aSi:H photodiode technology for advanced CMOS active pixel sensor imagers  

Microsoft Academic Search

Hydrogenated amorphous silicon (a-Si:H) holds the promise of realizing three-dimensional semiconductor integrated circuits by placing the photodiode above the pixel control circuitry rather than in-plane with it. This has the obvious advantages of enabling large die-size reduction and higher light collection efficiency compared to standard crystalline silicon arrays. We have developed a photodiode array technology that is fully compatible with

Jeremy A. Theil; Rick Snyder; David Hula; Kirk Lindahl; Homayoon Haddad; Jim Roland

2002-01-01

397

Gamma-ray multiplicity measurement of the spontaneous fission of 252Cf in a segmented HPGe/BGO detector array  

NASA Astrophysics Data System (ADS)

Coincident ? rays from a 252Cf source were measured using an array of six segmented high-purity germanium (HPGe) Clover detectors each enclosed by 16 bismuth-germanate (BGO) detectors. The detectors were arranged in a cubic pattern around a 1 ?Ci252Cf source to cover a large solid angle for ?-ray measurement with a reasonable reconstruction of the multiplicity. Neutron multiplicity was determined in certain cases by identifying the prompt ? rays from individual fission fragment pairs. Multiplicity distributions from previous experiments and theoretical models were convolved with the response function of the array and compared to the present results. These results suggest a ?-ray multiplicity spectrum broader than previous measurements and models, and provide no evidence of correlation with neutron multiplicity.

Bleuel, D. L.; Bernstein, L. A.; Burke, J. T.; Gibelin, J.; Heffner, M. D.; Mintz, J.; Norman, E. B.; Phair, L.; Scielzo, N. D.; Sheets, S. A.; Snyderman, N. J.; Stoyer, M. A.; Wiedeking, M.

2010-12-01

398

Some studies of avalanche photodiode readout of fast scintillators  

SciTech Connect

Photomultipliers (PMs) are the classical readout element for scintillation detectors in high energy particle physics, nuclear physics, medical physics, industrial radiation monitors etc. Here, large area avalanche photodiodes with high performance, narrow operation tolerances and high reliability have recently become available. The authors report on some tests of their performance in the readout of fast scintillators.

Holl, I.; Lorenz, E. [Max-Planck-Inst. fuer Physik, Muenchen (Germany)] [Max-Planck-Inst. fuer Physik, Muenchen (Germany); Natkaniez, S. [Inst. of Nuclear Physics, Krakow (Poland)] [Inst. of Nuclear Physics, Krakow (Poland); Renker, D. [Paul Scherrer Inst., Villigen (Switzerland)] [Paul Scherrer Inst., Villigen (Switzerland); Schmelz, C. [Max-Planck-Inst. fuer Physik, Muenchen (Germany)] [Max-Planck-Inst. fuer Physik, Muenchen (Germany); [Technische Univ. Muenchen (Germany). Nuklearmedizinische Klinik Rechts der Isar; Schwartz, B. [Budger Institute of Nuclear Physics, Novosibirsk (Russian Federation)] [Budger Institute of Nuclear Physics, Novosibirsk (Russian Federation)

1995-08-01

399

Thermal and Cold Neutron Computed Tomography at the Los Alamos Neutron Scattering Center Using an Amorphous Silicon Detector Array  

SciTech Connect

The use of the EG and G-Heimann RTM 128 or dpiX FS20 amorphous silicon (a-Si) detector array for thermal neutron radiography/computed tomography has proven to be a quick and efficient means of producing high quality digital radiographic images. The resolution, although not as good as film, is about 750 pm with the RTM and 127 pm with the dpiX array with a dynamic range in excess of 2,800. In many respects using an amorphous silicon detector is an improvement over other techniques such as imaging with a CCD camera, using a storage phosphor plate or film radiography. Unlike a CCD camera, which is highly susceptible to radiation damage, a-Si detectors can be placed in the beam directly behind the object under examination and do not require any special optics or turning mirrors. The amorphous silicon detector also allows enough data to be acquired to construct a digital image in just a few seconds (minimum gate time 40 ms) whereas film or storage plate exposures can take many minutes and then need to be digitized with a scanner. The flat panel can therefore acquire a complete 3D computed tomography data set in just a few tens of minutes. While a-Si detectors have been proposed for use in imaging neutron beams, this is the first reported implementation of such a detector for neutron imaging.

Claytor, T.N.; Schwab, M.J.; Farnum, E.H.; McDonald, T.E.; Summa, D.A.; Sheats, M.J.; Stupin, D.M.; Sievers, W.L.

1998-07-19

400

Exploitation of spatiotemporal information and geometric optimization of signal\\/noise performance using arrays of carbon black-polymer composite vapor detectors  

Microsoft Academic Search

We have investigated various aspects of the geometric and spatiotemporal response properties of an array of sorption-based vapor detectors. The detectors of specific interest are composites of insulating organic polymers filled with electrical conductors, wherein the detector film provides a reversible dc electrical resistance change upon the sorption of an analyte vapor. An analytical expression derived for the signal\\/noise performance

Shawn M. Briglin; Michael S. Freund; Phil Tokumaru; Nathan S. Lewis

2002-01-01

401

Hybrid avalanche photodiode ranging and photon-counting altimeter  

NASA Astrophysics Data System (ADS)

Avalanche photodiodes are very well suited and extensively used for low light application. In this paper we present a devise using avalanche photodiodes in conjunction with a pulsed laser-source to be used as an optical altimeter. The extreme sensitivity of a dedicated silicon SPAD array is combined with a versatile standard CMOS readout circuit to achieve unique performances. This imaging device is able to perform ranging with four centimeters accuracy over five kilometers distance. It is also capable of delivering quantum limited images. Development of the readout circuit will be disclosed as well as measurement results performed on the final device.

Dierickx, B.; Bellis, S.; Witvrouwen, N.; Dupont, B.; Defernez, A.; Jackson, C.

2010-10-01

402

Characterization of direct readout Si:Sb and Si:Ga infrared detector arrays for space-based astronomy  

NASA Technical Reports Server (NTRS)

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 microcomputer-based drive and readoaut electronics system. Preliminary Si:Sb measurements indicate a sense node capacitance of 0.06 pF, peak (28-micron) responsivity above 3 A/W at 2V bias, read noise of 130 rms e(-), dark current approximately 10 e(-)/s, and a well capacity greater than 10 to the 5th e(-). The limited test data available on the performance of the Si:Ga array are also discussed.

Mckelvey, Mark E.; Mccreight, Craig R.; Goebel, John H.; Moss, Nicolas N.; Savage, Maureen L.

1988-01-01

403

Uncooled infrared detector with 12?m pixel pitch video graphics array  

NASA Astrophysics Data System (ADS)

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.

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

404

Analysis of genetically modified organisms by pyrosequencing on a portable photodiode-based bioluminescence sequencer.  

PubMed

A portable bioluminescence analyser for detecting the DNA sequence of genetically modified organisms (GMOs) was developed by using a photodiode (PD) array. Pyrosequencing on eight genes (zSSIIb, Bt11 and Bt176 gene of genetically modified maize; Lectin, 35S-CTP4, CP4EPSPS, CaMV35S promoter and NOS terminator of the genetically modified Roundup ready soya) was successfully detected with this instrument. The corresponding limit of detection (LOD) was 0.01% with 35 PCR cycles. The maize and soya available from three different provenances in China were detected. The results indicate that pyrosequencing using the small size of the detector is a simple, inexpensive, and reliable way in a farm/field test of GMO analysis. PMID:24518318

Song, Qinxin; Wei, Guijiang; Zhou, Guohua

2014-07-01

405

Curved CCD detector devices and arrays for multispectral astrophysical applications and terrestrial stereo panoramic cameras  

NASA Astrophysics Data System (ADS)

The emergence of curved CCD detectors as individual devices or as contoured mosaics assembled to match the curved focal planes of astronomical telescopes and terrestrial stereo panoramic cameras represents a major optical design advancement that greatly enhances the scientific potential of such instruments. In altering the primary detection surface within the telescope"s optical instrumentation system from flat to curved, and conforming the applied CCD"s shape precisely to the contour of the telescope"s curved focal plane, a major increase in the amount of transmittable light at various wavelengths through the system is achieved. This in turn enables multi-spectral ultra-sensitive imaging with much greater spatial resolution necessary for large and very large telescope applications, including those involving infrared image acquisition and spectroscopy, conducted over very wide fields of view. For earth-based and space-borne optical telescopes, the advent of curved CCD"s as the principle detectors provides a simplification of the telescope"s adjoining optics, reducing the number of optical elements and the occurrence of optical aberrations associated with large corrective optics used to conform to flat detectors. New astronomical experiments may be devised in the presence of curved CCD applications, in conjunction with large format cameras and curved mosaics, including three dimensional imaging spectroscopy conducted over multiple wavelengths simultaneously, wide field real-time stereoscopic tracking of remote objects within the solar system at high resolution, and deep field survey mapping of distant objects such as galaxies with much greater multi-band spatial precision over larger sky regions. Terrestrial stereo panoramic cameras equipped with arrays of curved CCD"s joined with associative wide field optics will require less optical glass and no mechanically moving parts to maintain continuous proper stereo convergence over wider perspective viewing fields than their flat CCD counterparts, lightening the cameras and enabling faster scanning and 3D integration of objects moving within a planetary terrain environment. Preliminary experiments conducted at the Sarnoff Corporation indicate the feasibility of curved CCD imagers with acceptable electro-optic integrity. Currently, we are in the process of evaluating the electro-optic performance of a curved wafer scale CCD imager. Detailed ray trace modeling and experimental electro-optical data performance obtained from the curved imager will be presented at the conference.

Swain, Pradyumna; Mark, David

2004-09-01

406

Four-layer DOI PET detectors using a multi-pixel photon counter array and the light sharing method  

NASA Astrophysics Data System (ADS)

Silicon photomultipliers (SiPMs) provide many advantages for PET detectors, such as their high internal gain, high photon detection efficiency and insensitivity to magnetic fields. The number of detectable scintillation photons of SiPMs, however, is limited by the number of microcells. Therefore, pulse height of PET detectors using SiPMs is saturated when large numbers of scintillation photons enter the SiPM pixels. On the other hand, we previously presented a depth-of-interaction (DOI) encoding method that is based on the light sharing method. Since our encoding method detects scintillation photons with multiple readout pixels, the saturation effect can be suppressed. We constructed two prototype four-layer DOI detectors using a SiPM array and evaluated their performances. The two prototype detectors consisted of four layers of a 6×6 array of Lu2(1-x)Y2xSiO5 (LYSO) crystals and a SiPM (multi-pixel photon detector, MPPC, Hamamatsu Photonics K.K.) array of 4×4 pixels. The size of each LYSO crystal element was 1.46 mm×1.46 mm×4.5 mm and all surfaces of the crystal elements were chemically etched. We used two types of MPPCs. The first one had 3600 microcells and high photon detection efficiency (PDE). The other one had 14,400 microcells and lower PDE. In the evaluation experiment, all the crystals of the detector using the MPPC which had the high PDE were clearly identified. The respective energy and timing resolutions of lower than 15% and 1.0 ns were achieved for each crystal element. No saturation of output signals was observed in the 511 keV energy region due to suppression of the saturation effect by detecting scintillation photons with several MPPC pixels by the light sharing method.

Nishikido, Fumihiko; Inadama, Naoko; Yoshida, Eiji; Murayama, Hideo; Yamaya, Taiga

2013-11-01

407

Dark current study for CMOS fully integrated-PIN-photodiodes  

NASA Astrophysics Data System (ADS)

PIN photodiodes are semiconductor devices widely used in a huge range of applications, such as photoconductors, charge-coupled devices and pulse oximeters for medical applications. The possibility to combine and to integrate the fabrication of the sensor with its signal conditioning circuitry in a CMOS process allows device miniaturization in addition to enhance its properties lowering the production and assembly costs. This paper presents the design and characterization of silicon based PIN photodiodes integrated in a CMOS commercial process. A high-resistivity, low impurity substrate is chosen as the start material for the PIN photodiode array fabrication in order to fabricate devices with a minimum dark current. The dark current is studied, analyzed and measured for two different starting materials and for different geometries. A model previously proposed is reviewed and compared with experimental data.

Teva, Jordi; Jessenig, Stefan; Jonak-Auer, Ingrid; Schrank, Franz; Wachmann, Ewald

2011-05-01

408

Students using large muon detectors to investigate an array of cosmic ray phenomena  

NASA Astrophysics Data System (ADS)

During the summers of 2004 to 2008 high school students were given the opportunity to refurbish, characterize and ultimately experiment with large muon detectors at the University of Rochester. The 2.3 m^2 panels used for the cosmic ray investigations were remnants of the NuTeV experiment conducted at Fermilab in the late 1990's, and provided a means for measuring surface cosmic ray muon rates with high precision over many years of time. The first set of experiments carried out by students used data from two stacked paddles running in coincidence mode to detect significant muon fluctuations due to solar events, model an indirect relationship between muon frequency and atmospheric pressure, and determine if muon rates were dependent of the time of day. Current and archived data can be accessed at http://muon2.pas.rochester.edu/data/. In subsequent summers, students and teachers utilized four panel arrays to characterize directionality, angular distribution and frequency of atmospheric muon shower events. For all investigations students presented their findings to their peers and mentors via weekly seminars, e-logs, and poster sessions.

Sedita, Paul; McFarland, Kevin

2012-03-01

409

Evolution of miniature detectors and focal plane arrays for infrared sensors  

NASA Technical Reports Server (NTRS)

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.

Watts, Louis A.

1993-01-01

410

Evaluation of GM-APD array devices for low-light-level imaging  

NASA Astrophysics Data System (ADS)

The ability to count single photons is necessary to achieve many important science objectives in the near future. This paper presents the lab-tested performance of a photon-counting array-based Geiger-mode avalanche photodiode (GMAPD) device in the context of low-light-level imaging. Testing results include dark count rate, afterpulsing probability, intra-pixel sensitivity, and photon detection efficiency, and the effects of radiation damage on detector performance. The GM-APD detector is compared to the state-of-the-art performance of other established detectors using Signal-to-noise ratio as the overall evaluation metric.

Kolb, Kimberly; Hanold, Brandon; Lee, Joong; Figer, Donald F.

2014-05-01