High speed preamplifier circuit, detection electronics, and radiation detection systems therefrom

DOEpatents

Riedel, Richard A [Knoxville, TN; Wintenberg, Alan L [Knoxville, TN; Clonts, Lloyd G [Knoxville, TN; Cooper, Ronald G [Oak Ridge, TN

2010-09-21

A preamplifier circuit for processing a signal provided by a radiation detector includes a transimpedance amplifier coupled to receive a current signal from a detector and generate a voltage signal at its output. A second amplification stage has an input coupled to an output of the transimpedance amplifier for providing an amplified voltage signal. Detector electronics include a preamplifier circuit having a first and second transimpedance amplifier coupled to receive a current signal from a first and second location on a detector, respectively, and generate a first and second voltage signal at respective outputs. A second amplification stage has an input coupled to an output of the transimpedance amplifiers for amplifying the first and said second voltage signals to provide first and second amplified voltage signals. A differential output stage is coupled to the second amplification stage for receiving the first and second amplified voltage signals and providing a pair of outputs from each of the first and second amplified voltage signals. Read out circuitry has an input coupled to receive both of the pair of outputs, the read out circuitry having structure for processing each of the pair of outputs, and providing a single digital output having a time-stamp therefrom.

A Charge Sensitive Pre-Amplifier for Smart Point-of-Care Devices Employing Polymer Based Lab-on-a-Chip

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Hanfeng; Britton, Charles; Quaiyum, Farhan

With increasing emphasis on implantable and portable medical devices, low-power, small-chip-area sensor readout system realized in lab-on-a-chip (LOC) platform is gaining more and more importance these days. The main building blocks of the LOC system include a front-end transducer that generates an electrical signal in response to the presence of an analyte of interest, signal processing electronics to process the signal to comply with a specific transmission protocol and a low-power transmitter, all realized in a single integrated circuit platform. Low power consumption and compactness of the components are essential requirements of the LOC system. This paper presents a novelmore » charge sensitive pre-amplifier developed in a standard 180-nm CMOS process suitable for implementing in an LOC platform. The pre-amplifier converts the charge generated by a pyroelectric transducer into a voltage signal, which provides a measurement of the temperature variation in biological fluids. The proposed design is capable of providing 0.8-mV/pC gain while consuming only 2.1 μW of power. Finally, the pre-amplifier composed of integrated components occupies an area of 0.038 mm 2.« less

A Charge Sensitive Pre-Amplifier for Smart Point-of-Care Devices Employing Polymer Based Lab-on-a-Chip

DOE PAGES

Wang, Hanfeng; Britton, Charles; Quaiyum, Farhan; ...

2018-01-01

With increasing emphasis on implantable and portable medical devices, low-power, small-chip-area sensor readout system realized in lab-on-a-chip (LOC) platform is gaining more and more importance these days. The main building blocks of the LOC system include a front-end transducer that generates an electrical signal in response to the presence of an analyte of interest, signal processing electronics to process the signal to comply with a specific transmission protocol and a low-power transmitter, all realized in a single integrated circuit platform. Low power consumption and compactness of the components are essential requirements of the LOC system. This paper presents a novelmore » charge sensitive pre-amplifier developed in a standard 180-nm CMOS process suitable for implementing in an LOC platform. The pre-amplifier converts the charge generated by a pyroelectric transducer into a voltage signal, which provides a measurement of the temperature variation in biological fluids. The proposed design is capable of providing 0.8-mV/pC gain while consuming only 2.1 μW of power. Finally, the pre-amplifier composed of integrated components occupies an area of 0.038 mm 2.« less

Integrated front-end electronics in a detector compatible process: source-follower and charge-sensitive preamplifier configurations

NASA Astrophysics Data System (ADS)

Ratti, Lodovico; Manghisoni, Massimo; Re, Valerio; Speziali, Valeria

2001-12-01

This study is concerned with the simulation and design of low-noise front-end electronics monolithically integrated on the same high-resistivity substrate as multielectrode silicon detectors, in a process made available by the Istituto per la Ricerca Scientifica e Tecnologica (ITC-IRST) of Trento, Italy. The integrated front-end solutions described in this paper use N-channel JFETs as basic elements. The first one is based upon an all-NJFET charge preamplifier designed to match detector capacitances of a few picofarads and available in both a resistive and a non resistive feedback configuration. In the second solution, a single NJFET in the source-follower configuration is connected to the detector, while its source is wired to an external readout channel through an integrated capacitor.

Design of a 3T preamplifier which stability is insensitive to coil loading

NASA Astrophysics Data System (ADS)

Cao, Xueming; Fischer, Elmar; Korvink, Jan G.; Gruschke, Oliver; Hennig, Jürgen; Zaitsev, Maxim

2016-04-01

In MRI (magnetic resonance imaging), preamplifiers are needed to amplify signals obtained from MRI receiver coils. Under various loading conditions of the corresponding receiver coils, preamplifiers see different source impedance at their input and may become unstable. Therefore preamplifiers which stability is not sensitive to coil loading are desirable. In this article, a coil-loading-insensitive preamplifier for MRI is presented, derived from an unstable preamplifier. Different approaches to improve stability were used during this derivation. Since a very low noise factor is essential for MRI preamplifiers, noise contributions from passive components in the MRI preamplifier have to be considered during the stabilization process. As a result, the initially unstable preamplifier became stable with regard to coil loading, while other MRI requirements, as the extremely low noise factor, were still fulfilled. The newly designed preamplifier was manufactured, characterized and tested in the MRI spectrometer. Compared to a commercially available preamplifier, the newly designed preamplifier has similar imaging performance but other advantages like smaller size and better stability. Furthermore, presented stabilization approaches can be generalized to stabilize other unstable low-noise amplifiers.

Performance evaluation of the analogue front-end and ADC prototypes for the Gotthard-II development

NASA Astrophysics Data System (ADS)

Zhang, J.; Andrä, M.; Barten, R.; Bergamaschi, A.; Brückner, M.; Dinapoli, R.; Fröjdh, E.; Greiffenberg, D.; Lopez-Cuenca, C.; Mezza, D.; Mozzanica, A.; Ramilli, M.; Redford, S.; Ruat, M.; Ruder, C.; Schmitt, B.; Shi, X.; Thattil, D.; Tinti, G.; Turcato, M.; Vetter, S.

2017-12-01

Gotthard-II is a silicon microstrip detector developed for the European X-ray Free-Electron Laser (XFEL.EU). Its potential scientific applications include X-ray absorption/emission spectroscopy, hard X-ray high resolution single-shot spectrometry (HiREX), energy dispersive experiments at 4.5 MHz frame rate, beam diagnostics, as well as veto signal generation for pixel detectors. Gotthard-II uses a silicon microstrip sensor with a pitch of 50 μm or 25 μm and with 1280 or 2560 channels wire-bonded to readout chips (ROCs). In the ROC, an adaptive gain switching pre-amplifier (PRE), a fully differential Correlated-Double-Sampling (CDS) stage, an Analog-to-Digital Converter (ADC) as well as a Static Random-Access Memory (SRAM) capable of storing all the 2700 images in an XFEL.EU bunch train will be implemented. Several prototypes with different designs of the analogue front-end (PRE and CDS) and ADC test structures have been fabricated in UMC-110 nm CMOS technology and their performance has been evaluated. In this paper, the performance of the analogue front-end and ADC will be summarized.

A system for automated noise parameter measurements on MR preamplifiers and application to high B(0) fields.

PubMed

Lagore, Russell L; Roberts, Brodi Roduta; Possanzini, Cecilia; Saylor, Charles; Fallone, B Gino; De Zanche, Nicola

2014-08-01

A noise figure and noise parameter measurement system was developed that consists of a combination spectrum and network analyzer, preamplifier, programmable power supply, noise source, tuning board, and desktop computer. The system uses the Y-factor method for noise figure calculation and allows calibrations to correct for a decrease in excess noise ratio between the noise source and device under test, second stage (system) noise, ambient temperature variations, and available gain of the device under test. Noise parameters are extracted by performing noise figure measurements at several source impedance values obtained by adjusting an electronically controlled tuner. Results for several amplifiers at 128 MHz and 200 MHz agree with independent measurements and with the corresponding datasheets. With some modifications, the system was also used to characterize the noise figure of MRI preamplifiers in strong static magnetic fields up to 9.4 T. In most amplifiers tested the gain was found to be reduced by the magnetic field, while the noise figure increased. These changes are detrimental to signal quality (SNR) and are dependent on the electron mobility and design of the amplifier's semiconductor devices. Consequently, gallium arsenide (GaAs) field-effect transistors are most sensitive to magnetic fields due to their high electron mobility and long, narrow channel, while silicon-germanium (SiGe) bipolar transistor amplifiers are largely immune due to their very thin base. Copyright © 2014 John Wiley & Sons, Ltd.

High density processing electronics for superconducting tunnel junction x-ray detector arrays

NASA Astrophysics Data System (ADS)

Warburton, W. K.; Harris, J. T.; Friedrich, S.

2015-06-01

Superconducting tunnel junctions (STJs) are excellent soft x-ray (100-2000 eV) detectors, particularly for synchrotron applications, because of their ability to obtain energy resolutions below 10 eV at count rates approaching 10 kcps. In order to achieve useful solid detection angles with these very small detectors, they are typically deployed in large arrays - currently with 100+ elements, but with 1000 elements being contemplated. In this paper we review a 5-year effort to develop compact, computer controlled low-noise processing electronics for STJ detector arrays, focusing on the major issues encountered and our solutions to them. Of particular interest are our preamplifier design, which can set the STJ operating points under computer control and achieve 2.7 eV energy resolution; our low noise power supply, which produces only 2 nV/√Hz noise at the preamplifier's critical cascode node; our digital processing card that digitizes and digitally processes 32 channels; and an STJ I-V curve scanning algorithm that computes noise as a function of offset voltage, allowing an optimum operating point to be easily selected. With 32 preamplifiers laid out on a custom 3U EuroCard, and the 32 channel digital card in a 3U PXI card format, electronics for a 128 channel array occupy only two small chassis, each the size of a National Instruments 5-slot PXI crate, and allow full array control with simple extensions of existing beam line data collection packages.

Industrial universal electrometer

DOEpatents

Cordaro, Joseph V [Martinez, GA; Wood, Michael B [Aiken, SC

2012-07-03

An electrometer for use in measuring current is provided. The electrometer includes an enclosure capable of containing various components of the electrometer. A pre-amplifier is present and is one of the components of the electrometer. The pre-amplifier is contained by the enclosure. The pre-amplifier has a pre-amplifier enclosure that contains the pre-amplifier and provides radio frequency shielding and magnetic shielding to the pre-amplifier.

A front-end electronic system for large arrays of bolometers

NASA Astrophysics Data System (ADS)

Arnaboldi, C.; Carniti, P.; Cassina, L.; Gotti, C.; Liu, X.; Maino, M.; Pessina, G.; Rosenfeld, C.; Zhu, B. X.

2018-02-01

CUORE is an array of thermal calorimeters composed of 988 crystals held at about 10 mK, whose absorbed energy is read out with semiconductor thermistors. The composition of the crystal is TeO2, and the aim is the study of the double beta decay of 130Te on very long and stable runs. CUPID-0 is an array of 26 Zn82Se crystals with double thermistor readout to study the double beta decay of 82Se. In the present paper, we present an overview of the entire front-end electronic readout chain, from the preamplifier to the anti-aliasing filter. This overview includes motivations, design strategies, circuit implementation and performance results of the electronic system, including other auxiliary yet important elements like power supplies and the slow control communication system. The stringent requirements of stability on the very long experimental runs that are foreseen during CUORE and CUPID-0 operation, are achieved thanks to novel solutions of the front-end preamplifier and of the detector bias circuit setup.

A low-noise CMOS pixel direct charge sensor, Topmetal-II-

DOE PAGES

An, Mangmang; Chen, Chufeng; Gao, Chaosong; ...

2015-12-12

In this paper, we report the design and characterization of a CMOS pixel direct charge sensor, Topmetal-II-, fabricated in a standard 0.35 μm CMOS Integrated Circuit process. The sensor utilizes exposed metal patches on top of each pixel to directly collect charge. Each pixel contains a low-noise charge-sensitive preamplifier to establish the analog signal and a discriminator with tunable threshold to generate hits. The analog signal from each pixel is accessible through time-shared multiplexing over the entire array. Hits are read out digitally through a column-based priority logic structure. Tests show that the sensor achieved a <15e - analog noisemore » and a 200e - minimum threshold for digital readout per pixel. The sensor is capable of detecting both electrons and ions drifting in gas. Lastly, these characteristics enable its use as the charge readout device in future Time Projection Chambers without gaseous gain mechanism, which has unique advantages in low background and low rate-density experiments.« less

A low-noise CMOS pixel direct charge sensor, Topmetal-II-

DOE Office of Scientific and Technical Information (OSTI.GOV)

An, Mangmang; Chen, Chufeng; Gao, Chaosong

In this paper, we report the design and characterization of a CMOS pixel direct charge sensor, Topmetal-II-, fabricated in a standard 0.35 μm CMOS Integrated Circuit process. The sensor utilizes exposed metal patches on top of each pixel to directly collect charge. Each pixel contains a low-noise charge-sensitive preamplifier to establish the analog signal and a discriminator with tunable threshold to generate hits. The analog signal from each pixel is accessible through time-shared multiplexing over the entire array. Hits are read out digitally through a column-based priority logic structure. Tests show that the sensor achieved a <15e - analog noisemore » and a 200e - minimum threshold for digital readout per pixel. The sensor is capable of detecting both electrons and ions drifting in gas. Lastly, these characteristics enable its use as the charge readout device in future Time Projection Chambers without gaseous gain mechanism, which has unique advantages in low background and low rate-density experiments.« less

Signal Statistics and Maximum Likelihood Sequence Estimation in Intensity Modulated Fiber Optic Links Containing a Single Optical Pre-amplifier.

PubMed

Alić, Nikola; Papen, George; Saperstein, Robert; Milstein, Laurence; Fainman, Yeshaiahu

2005-06-13

Exact signal statistics for fiber-optic links containing a single optical pre-amplifier are calculated and applied to sequence estimation for electronic dispersion compensation. The performance is evaluated and compared with results based on the approximate chi-square statistics. We show that detection in existing systems based on exact statistics can be improved relative to using a chi-square distribution for realistic filter shapes. In contrast, for high-spectral efficiency systems the difference between the two approaches diminishes, and performance tends to be less dependent on the exact shape of the filter used.

Development of cryogenic CMOS Readout ASICs for the Point-Contact HPGe Detectors for Dark Matter Search and Neutrino Experiments

NASA Astrophysics Data System (ADS)

Deng, Zhi; He, Li; Liu, Feng; Liu, Yinong; Xue, Tao; Li, Yulan; Yue, Qian

2017-05-01

The paper presents the developments of two cryogenic readout ASICs for the point-contact HPGe detectors for dark matter search and neutrino experiments. Extremely low noise readout electronics were demanded and the capability of working at cryogenic temperatures may bring great advantages. The first ASIC was a monolithic CMOS charge sensitive preamplifier with its noise optimized for ∼1 pF input capacitance. The second ASIC was a waveform recorder based on switched capacitor array. These two ASICs were fabricated in CMOS 350 nm and 180 nm processes respectively. The prototype chips were tested and showed promising results. Both ASICs worked well at low temperature. The preamplifier had achieved ENC of 10.3 electrons with 0.7 pF input capacitance and the SCA chip could run at 9 bit effective resolution and 25 MSPS sampling rate.

Direct matching methods for coils and preamplifiers in MRI

NASA Astrophysics Data System (ADS)

Cao, Xueming; Fischer, Elmar; Hennig, Jürgen; Zaitsev, Maxim

2018-05-01

In this paper, direct matching methods for coils and preamplifiers in receiver arrays are presented. Instead of compensating the reactance of the input impedance of preamplifiers, in our method, the reactance was used to resonate with the coil matching networks and thus to decouple the coils. Furthermore, coil matching networks and preamplifier input matching networks were combined, meaning the coil loop can be matched to the transistor in the preamplifier directly. These matching methods and, for comparison, the conventional matching method were implemented with custom-made preamplifiers and coils. Decoupling and noise-matching performance were compared between these three configurations. Phase shifting networks between coils and preamplifiers are not necessary in our matching methods. With fewer components, these matching networks showed lower noise factors, while similar preamplifier-decoupling performance was found for all three methods.

Cold hybrid electronics for CIRS-Cassini

NASA Astrophysics Data System (ADS)

Picault, Robert; Royer, Michel; Vannier, Patrice; De Antoni, Philippe; Lapegue, Jacques; Quatrehomme, Franck

1995-09-01

Cassini/Huygens is a joint NASA/ESA planetary mission to the Saturnian system. Titan, the largest Saturn moon, is the major target of the mission. Cassini is the Saturn orbiter provided by NASA to be launched on October 1997. To reach planet Saturn in 2004 and to study the rings, the planet and its satellites, the Cassini/Huygens planetary mission, a NASA-JPL project, includes among 12 instruments, the composite infrared spectrometer (CIRS) with GSFC as prime contractor of this instrument. The French participants are the Service d'Astrophysique (SAp) of CEA-Saclay and the DESPA-Observatoire de Meudon. CEA/SAp is in charge of the focal plane 4 electronics (detector, cold preamplifier, and analog processing electronic). SAT has developed under a CEA-SAp contract the hybrid micro-circuit which ensures the preamplifying function. These transimpedance amplifiers operate at 170 K and consist of 10 channels. The input current from the detector is up to 60 nA (mainly background current, modulated by a signal in the pA-nA range) and is converted into voltage up to 1.2 V through a 20 M(Omega) feedback resistor. The noise is < 15 nV/(root)Hz. The stability of the resistors is expected to be 0.1% for a duration of 16 years. The lifetime reuqirement consists of: 1) ground storage: 3-4 years, 2) transfer orbit: 7 years (instrument not operating), 3) Saturnian orbit: 4-5 years (instrument operating) and more than 40 Saturn-centered orbits. The preamplifier hybrid is an operational amplifier using a resistor multichip substrate designed, manufactured, and selected according to ESA PSS and MIL applicable documents. This amplifier integrated circuit has been chosen taking into account its cold temperature electrical performance and on the basis of its radiation resistance to 100 krad (at 170 K and operating). The model philosophy includes 2 main deliveries: engineering models and flight/spare models. The evaluation program consists of the electrical testing of all component parameters at 293 K and 170 K, and lifetime tests (burn-in, thermal cycling). The preamplifier hybrids are mounted in packages, hermetically laser-sealed with dry gas atmosphere.

Evaluation of Two Guralp Preamplifiers for GS13 Seismometer Application.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merchant, Bion J.

Sandia National Laboratories has tested and evaluated a new preamplifier, the Guralp Preamplifier for GS13, manufactured by Guralp. These preamplifiers are used to interface between Guralp digitizers and Geotech GS13 Seismometers. The purpose of the preamplifier evaluation was to measure the performance characteristics in such areas as power consumption, input impedance, sensitivity, full scale, self-noise, dynamic range, system noise, response, passband, and timing. The Guralp GS13 Preamplifiers are being evaluated for potential use in the International Monitoring System (IMS) of the Comprehensive Nuclear Test-Ban-Treaty Organization (CTBTO).

Short wavelength HgCdTe staring focal plane for low background astronomy applications

NASA Technical Reports Server (NTRS)

Hall, D.; Stobie, J.; Hartle, N.; Lacroix, D.; Maschhoff, K.

1989-01-01

The design of a 128x128 staring short wave infrared (SWIR) HgCdTe focal plane incorporating charge integrating transimpedance input preamplifiers is presented. The preamplifiers improve device linearity and uniformity, and provide signal gain ahead of the miltiplexer and readout circuitry. Detector's with cutoff wavelength of 2.5 microns and operated at 80 K have demonstrated impedances in excess of 10(exp 16) ohms with 60 percent quantum efficiency. Focal plane performance using a smaller format device is presented which demonstrates the potential of this approach. Although the design is capable of achieving less than 30 rms electrons with todays technology, initial small format devices demonstrated a read noise of 100 rms electrons and were limited by the atypical high noise performance of the silicon process run. Luminescence from the active silicon circuitry in the multiplexer limits the minimum detector current to a few hundred electrons per second. Approaches to eliminate this excessive source of current is presented which should allow the focal plane to achieve detector background limited performance.

Near Field Imaging for the Characterization of Diffusion Length and Waveguiding in Zinc Oxide Nanowires

DTIC Science & Technology

2012-06-01

From RADAR and SONAR , rocket propulsion, and the atomic bomb in World War II to the high tech drones, satellite imagery, surgically precise weapons...control from the four connectors shown in Figure scanner, preamplifier , step motor, and the bottom scanner. The connectors also electrically ground

Compact Circuit Preprocesses Accelerometer Output

NASA Technical Reports Server (NTRS)

Bozeman, Richard J., Jr.

1993-01-01

Compact electronic circuit transfers dc power to, and preprocesses ac output of, accelerometer and associated preamplifier. Incorporated into accelerometer case during initial fabrication or retrofit onto commercial accelerometer. Made of commercial integrated circuits and other conventional components; made smaller by use of micrologic and surface-mount technology.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lombigit, L., E-mail: lojius@nm.gov.my; Rahman, Nur Aira Abd; Mohamad, Glam Hadzir Patai

A radioisotope identifier device based on large volume Co-planar grid CZT detector is current under development at Malaysian Nuclear Agency. This device is planned to be used for in-situ identification of radioisotopes based on their unique energies. This work reports on electronics testing performed on the front-end electronics (FEE) analog section comprising charge sensitive preamplifier-pulse shaping amplifier chain. This test involves measurement of charge sensitivity, pulse parameters and electronics noise. This report also present some preliminary results on the spectral measurement obtained from gamma emitting radioisotopes.

Wide-band current preamplifier for conductance measurements with large input capacitance.

PubMed

Kretinin, Andrey V; Chung, Yunchul

2012-08-01

A wide-band current preamplifier based on a composite operational amplifier is proposed. It has been shown that the bandwidth of the preamplifier can be significantly increased by enhancing the effective open-loop gain. The described 10(7) V/A current gain preamplifier had the bandwidth of about 100 kHz with the 1 nF input shunt capacitance. The measured preamplifier current noise was 46 fA/√Hz at 1 kHz, close to the design noise minimum. The voltage noise was found to be about 2.9 nV/√Hz at 1 kHz, which is in a good agreement with the value expected for the particular operational amplifier used in the input stage. By analysing the total produced noise we found that the optimal frequency range suitable for the fast lock-in measurements is from 1 kHz to 2 kHz. To obtain the same signal-to-noise ratio, the reported preamplifier requires ~10% of the integration time needed in measurements made with a conventional preamplifier.

Task three: Report: STDN Antenna and preamplifier cost tradeoff study. [combinations of antennas and preamplifiers for several communication environments

NASA Technical Reports Server (NTRS)

1973-01-01

The general goal of this task, STDN Antenna and Preamplifier G/T Study, was to determine cost-effective combinations of antennas and preamplifiers for several sets of conditions for frequency, antenna elevation angle, and rain. The output of the study includes design curves and tables which indicate the best choice of antenna size and preamplifier type to provide a given G/T performance. The report indicates how to evaluate the cost effectiveness of proposed improvements to a given station. Certain parametric variations are presented to emphasize the improvement available by reducing RF losses and improving the antenna feed.

DESIGN NOTE: A modified Nanosurf scanning tunnelling microscope for ballistic electron emission microscopy and spectroscopy

NASA Astrophysics Data System (ADS)

Appelbaum, Ian; Thompson, Pete; van Schendel, P. J. A.

2006-04-01

We describe the design and implementation of modifications to an ambient STM with a slip stick approach mechanism to create a system capable of ballistic electron emission microscopy (BEEM) and spectroscopy (BEES). These modifications require building a custom sample holder which operates as a high gain transimpedance preamplifier. Results of microscopy and spectroscopy using a Au/n-GaAs Schottky device demonstrate the effectiveness of our design.

Eine 200-μm-Kamera zur unvollständigen Himmelsdurchmusterung mit dem ISO-Satelliten.

NASA Astrophysics Data System (ADS)

Burgdorf, M.

The C200 camera designed for the wavelength range >160 μm is composed of the detector elements and their preamplifiers. The limiting sensitivity to be reached is estimated. In building the infrared satellite experiment ISOPHOT the detector arrays and selecting electronics are of key importance.

Pulsed Power Design for a Small Repetitively Pulsed Electron Beam Pumped KrF Laser

DTIC Science & Technology

2003-06-01

fusion energy (IFE) requirements for rep-rate, efficiency, durability and cost. We have designed a pulsed power system for the pre-amplifier in the Electra...new advanced pulsed power topology that can meet the fusion energy requirements for durability, repetition rate, and cost. The pulsed power will first

RF surface receive array coils: the art of an LC circuit.

PubMed

Fujita, Hiroyuki; Zheng, Tsinghua; Yang, Xiaoyu; Finnerty, Matthew J; Handa, Shinya

2013-07-01

The radiofrequency (RF) receive array coil is a complicated device with many inductors and capacitors and serves as one of the most critical magnetic resonance imaging (MRI) electronic devices. It directly determines the achievable level of signal-to-noise ratio (SNR). Simply put, however, the RF coil is nothing but an LC circuit. The receive array coil was first proposed more than 20 years ago, evolving from a simple arrangement with a few electronic channels to a complicated system of 128 channels, enabling highly sophisticated parallel imaging, at different field strengths. This article summarizes the basic concepts pertaining to RF receive coil arrays and their associated SNR and reviews the theories behind the major components of such arrays. This includes discussions of the intrinsic SNR of a receive coil, the matching circuits, low-noise preamplifiers, coupling/decoupling amongst coils, the coupling between receive and transmit coils, decoupling via preamplifiers, and baluns. An 8-channel receive array coil on a cylindrical former serves as a useful example for demonstrating various points in the review. Copyright © 2013 Wiley Periodicals, Inc.

Direct detection optical intersatellite link at 220 Mbps using AlGaAs laser diode and silicon APD with 4-ary PPM signaling

NASA Technical Reports Server (NTRS)

Sun, Xiaoli; Davidson, Frederic M.

1990-01-01

A newly developed 220 Mbps free-space 4-ary pulse position modulation (PPM) direct detection optical communication system is described. High speed GaAs integrated circuits were used to construct the PPM encoder and receiver electronic circuits. Both PPM slot and word timing recovery were provided in the PPM receiver. The optical transmitter consisted of an AlGaAs laser diode (Mitsubishi ML5702A, lambda=821nm) and a high speed driver unit. The photodetector consisted of a silicon avalanche photodiode (APD) (RCA30902S) preceded by an optical interference filter (delta lambda=10nm). Preliminary tests showed that the self-synchronized PPM receiver could achieve a receiver bit error rate of less than 10(exp -6) at 25 nW average received optical signal power or 360 photons per transmitted information bit. The relatively poor receiver sensitivity was believed to be caused by the insufficient electronic bandwidth of the APD preamplifier and the poor linearity of the preamplifier high frequency response.

Enhancement of High-Speed Infrared Array Electronics (Center Director's Discretionary Fund)

NASA Technical Reports Server (NTRS)

Sutherland, W. T.

1996-01-01

A state-of-the-art infrared detector was to be used as the sensor in a new spectrometer-camera for astronomical observations. The sensitivity of the detector required the use of low-noise, high-speed electronics in the system design. The key component in the electronic system was the pre-amplifier that amplified the low voltage signal coming from the detector. The system was designed based on the selection of the amplifier and that was driven by the maximum noise level, which would yield the desired sensitivity for the telescope system.

The 150 ns detector project: Prototype preamplifier results

NASA Astrophysics Data System (ADS)

Warburton, W. K.; Russell, S. R.; Kleinfelder, Stuart A.

1994-08-01

The long-term goal of the 150 ns detector project is to develop a pixel area detector capable of 6 MHz frame rates (150 ns/frame). Our milestones toward this goal are: a single pixel, 1×256 1D and 8×8 2D detectors, 256×256 2D detectors and, finally, 1024 × 1024 2D detectors. The design strategy is to supply a complete electronics chain (resetting preamp, selectable gain amplifier, analog-to-digital converter (ADC), and memory) for each pixel. In the final detectors these will all be custom integrated circuits. The front-end preamplifiers are integrated first, since their design and performance are the most unusual and also critical to the project's success. Similarly, our early work is concentrated on devising and perfecting detector structures. In this paper we demonstrate the performance of prototypes of our integrated preamplifiers. While the final design will have 64 preamps to a chip, including a switchable gain stage, the prototypes were integrated 8 channels to a "Tiny Chip" and tested in 4 configurations (feedback capacitor Cf equal 2.5 or 4.0 pF, output directly or through a source follower). These devices have been tested thoroughly for reset settling times, gain, linearity, and electronic noise. They generally work as designed, being fast enough to easily integrate detector charge, settle, and reset in 150 ns. Gain and linearity appear to be acceptable. Current values of electronic noise, in double-sampling mode, are about twice the design goal of {2}/{3} of a single photon at 6 keV. We expect this figure to improve with the addition of the onboard amplifier stage and improved packaging. Our next test chip will include these improvements and allow testing with our first detector samples, which will be 1×256 (50 μm wide pixels) and 8×8 (1 mm 2 pixels) element detector on 1 mm thick silicon.

Application of low-noise CID imagers in scientific instrumentation cameras

NASA Astrophysics Data System (ADS)

Carbone, Joseph; Hutton, J.; Arnold, Frank S.; Zarnowski, Jeffrey J.; Vangorden, Steven; Pilon, Michael J.; Wadsworth, Mark V.

1991-07-01

CIDTEC has developed a PC-based instrumentation camera incorporating a preamplifier per row CID imager and a microprocessor/LCA camera controller. The camera takes advantage of CID X-Y addressability to randomly read individual pixels and potentially overlapping pixel subsets in true nondestructive (NDRO) as well as destructive readout modes. Using an oxy- nitride fabricated CID and the NDRO readout technique, pixel full well and noise levels of approximately 1*10(superscript 6) and 40 electrons, respectively, were measured. Data taken from test structures indicates noise levels (which appear to be 1/f limited) can be reduced by a factor of two by eliminating the nitride under the preamplifier gate. Due to software programmability, versatile readout capabilities, wide dynamic range, and extended UV/IR capability, this camera appears to be ideally suited for use in spectroscopy and other scientific applications.

Implementation of the Phase Difference Trace Function for a Circular Array.

DTIC Science & Technology

1980-06-01

15 B. HICROPHONES............... ... .. ..... ....... 16 C. PREAMPLIFIER /FILTER ................. o....... 16 D. PHASE SHIFrER...Photgraphs ......................... 31 5. Microphone Specifications ........................... 32 6. Preamplifier /Filter Schematic...33 7. Preamplifier /Filter Printel Cir-cait Board ........... 34 8. Phase Shifter Schemitic ............................. 35 9. Phase Shifter Print.l

X-ray and gamma ray detector readout system

DOEpatents

Tumer, Tumay O; Clajus, Martin; Visser, Gerard

2010-10-19

A readout electronics scheme is under development for high resolution, compact PET (positron emission tomography) imagers based on LSO (lutetium ortho-oxysilicate, Lu.sub.2SiO.sub.5) scintillator and avalanche photodiode (APD) arrays. The key is to obtain sufficient timing and energy resolution at a low power level, less than about 30 mW per channel, including all required functions. To this end, a simple leading edge level crossing discriminator is used, in combination with a transimpedance preamplifier. The APD used has a gain of order 1,000, and an output noise current of several pA/ Hz, allowing bipolar technology to be used instead of CMOS, for increased speed and power efficiency. A prototype of the preamplifier and discriminator has been constructed, achieving timing resolution of 1.5 ns FWHM, 2.7 ns full width at one tenth maximum, relative to an LSO/PMT detector, and an energy resolution of 13.6% FWHM at 511 keV, while operating at a power level of 22 mW per channel. Work is in progress towards integration of this preamplifier and discriminator with appropriate coincidence logic and amplitude measurement circuits in an ASIC suitable for a high resolution compact PET instrument. The detector system and/or ASIC can also be used for many other applications for medical to industrial imaging.

Fast wire per wire X-ray data acquisition system for time-resolved small angle scattering experiments

NASA Astrophysics Data System (ADS)

Epstein, A.; Briquet-Laugier, F.; Sheldon, S.; Boulin, C.

2000-04-01

Most of the X-ray multi-wire gas detectors used at the EMBL Hamburg outstation for time-resolved studies of biological samples are readout, using the delay line method. The main disadvantage of such readout systems is their event rate limitation introduced by the delay line and the required time to digital conversion step. They also lack the possibility to deal with multiple events. To overcome these limitations, a new approach for the complete readout system was introduced. The new linear detection system is based on the wire per wire approach where each individual wire is associated to preamplifier/discriminator/counter electronics channel. High-density, front-end electronics were designed around a fast current sensitive preamplifier. An eight-channel board was designed to include the preamplifiers-discriminators and the differential ECL drivers output stages. The detector front-end consists of 25 boards directly mounted inside the detector assembly. To achieve a time framing resolution as short as 10 /spl mu/s, very fast histogramming is required. The only way to implement this for a high number of channels (200 in our case) is by using a distributed system. The digital part of the system consists of a crate controller, up to 16 acquisition boards (capable of handling fast histogramming for up to 32-channels each) and an optical-link board (based on the Cypress "Hot-Link" chip set). Both the crate controller and the acquisition boards are based on a standard RISC microcontroller (IDT R3081) plug-in board. At present, a dedicated CAMAC module which we developed is used to interface the digital front-end acquisition crate to the host via the optical link.

Pre-experiment testing of the Multi Channel Systems 16-channel preamplifier CPA16

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patin, J B; Stoyer, M A; Moody, K J

2003-11-03

The 16-channel preamplifier model CPA16 from Multi Channel Systems was studied. The CPA16 preamplifier/amplifier module is a candidate to be used as the preamplifiers and amplifiers for the focal plane detectors of the Mass Analyzer of Super Heavy Atoms (MASHA). The equipment used to test the CPA16, the results of testing the CPA16 with a pulser, a mixed {sup 229}Th/{sup 148}Gd source and a {sup 252}Cf source, and a summary of the results will be presented.

Development of Integrated Preamplifier for High-Frequency Ultrasonic Transducers and Low-Power Handheld Receiver

PubMed Central

Choi, Hojong; Li, Xiang; Lau, Sien-Ting; Hu, ChangHong; Zhou, Qifa; Shung, K. Kirk

2012-01-01

This paper describes the design of a front-end circuit consisting of an integrated preamplifier with a Sallen-Key Butterworth filter for very-high-frequency ultrasonic transducers and a low-power handheld receiver. This preamplifier was fabricated using a 0.18-μm 7WL SiGe bi-polar complementary metal oxide semiconductor (BiCMOS) process. The Sallen-Key filter is used to increase the voltage gain of the front-end circuit for high-frequency transducers which are generally low in sensitivity. The measured peak voltage gain of the frontend circuits for the BiCMOS preamplifier with the Sallen-Key filter was 41.28 dB at 100 MHz with a −6-dB bandwidth of 91%, and the dc power consumption of the BiCMOS preamplifier was 49.53 mW. The peak voltage gain of the front-end circuits for the CMOS preamplifier with the Sallen-Key filter was 39.52 dB at 100 MHz with a −6-dB bandwidth of 108%, and the dc power consumption of the CMOS preamplifier was 43.57 mW. Pulse-echo responses and wire phantom images with a single-element ultrasonic transducer have been acquired to demonstrate the performance of the front-end circuit. PMID:23443700

Bloch oscillating transistor as the readout element for hot electron bolometers

NASA Astrophysics Data System (ADS)

Hassel, Juha; Seppä, Heikki; Lindell, Rene; Hakonen, Pertti

2004-10-01

In this paper we analyse the properties of the Bloch oscillating transistor as a preamplifier in cryogenic devices. We consider here especially the readout of hot electron bolometers (HEBs) based on Normal-Superconductor-Insulator tunnel junctions, but the results also apply more generally. We show that one can get an equivalent noise voltage below 1 nV/√Hz with a single BOT. By using N BOTs in a parallel array configuration, a further reduction by factor √N may be achieved.

Design and performance of the readout electronics chain of the Delphi Forward Ring Imaging Cherenkov Detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dam, P.; Nielsen, B.S.; Formenti, F.

1992-10-01

In this paper the Front End Readout electronics chain of the Forward Ring Imaging CHerenkov (FRICH) Detector used at the Delphi experiment of the Large Electron Positron (LEP) collider is presented. The system incorporates a wide band low noise preamplifier, mounted in the proximity of the MultiWire Proportional Chamber, an Amplifying-Discriminating-Multiple-xing FASTBUS unit for further signal amplification, discrimination and channel reduction and a LEP Time Digitizer FASTBUS unit for time digitization. The paper gives a general view of the detector and its electronics with particular emphasis on the novel characteristics and capabilities of the system.

The UT 19-channel DC SQUID based neuromagnetometer.

PubMed

ter Brake, H J; Flokstra, J; Jaszczuk, W; Stammis, R; van Ancum, G K; Martinez, A; Rogalla, H

1991-01-01

A 19-channel DC SQUID based neuromagnetometer is under construction at the University of Twente (UT). Except for the cryostat all elements of the system are developed at the UT. It comprises 19 wire-wound first-order gradiometers in a hexagonal configuration. The gradiometers are connected to planar DC SQUIDs fabricated with a Nb/Al, AlO kappa/Nb technology. For this connection we developed a method to bond a Nb wire to a Nb thin-film. The SQUIDs are placed in compartmentalised Nb modules. Further, external feedback is incorporated in order to eliminate cross talk between the gradiometers. The electronics basically consist of a phase-locked loop operating with a modulation frequency of 100 kHz. Between SQUID and preamplifier a small transformer is used to limit the noise contribution of the preamplifier. In the paper the overall system is described, and special attention is paid to the SQUID module (bonding, compartments, external-feedback setup, output transformer).

Nuclear spin noise in NMR revisited

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferrand, Guillaume; Luong, Michel; Huber, Gaspard

2015-09-07

The theoretical shapes of nuclear spin-noise spectra in NMR are derived by considering a receiver circuit with finite preamplifier input impedance and a transmission line between the preamplifier and the probe. Using this model, it becomes possible to reproduce all observed experimental features: variation of the NMR resonance linewidth as a function of the transmission line phase, nuclear spin-noise signals appearing as a “bump” or as a “dip” superimposed on the average electronic noise level even for a spin system and probe at the same temperature, pure in-phase Lorentzian spin-noise signals exhibiting non-vanishing frequency shifts. Extensive comparisons to experimental measurementsmore » validate the model predictions, and define the conditions for obtaining pure in-phase Lorentzian-shape nuclear spin noise with a vanishing frequency shift, in other words, the conditions for simultaneously obtaining the spin-noise and frequency-shift tuning optima.« less

Evaluation of Two Guralp Preamplifiers for GS21 Seismometer Application.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merchant, Bion J.; Slad, George William

2015-08-01

Sandia National Laboratories has tested and evaluated two Guralp preamplifiers for use with a GS21 seismometer application. The two preamplifiers have a gain factor of 61.39. The purpose of the preamplifier evaluation was to determine a measured gain factor, transfer function, total harmonic distortion, self-noise, application passband, dynamic range, seismometer calibration pass-through, and to comment on any issues encountered during the evaluation. The test results included in this report were in response to static, tonal, and dynamic input signals. The Guralp GS21 preamplifiers are being evaluated for potential use in the International Monitoring System (IMS) of the Comprehensive Nuclear Test-Ban-Treatymore » Organization (CTBTO). Test methodologies used were based on IEEE Standards 1057 for Digitizing Waveform Recorders and 1241 for Analog to Digital Converters« less

Ready to use detector modules for the NEAT spectrometer: Concept, design, first results

NASA Astrophysics Data System (ADS)

Magi, Ádám; Harmat, Péter; Russina, Margarita; Günther, Gerrit; Mezei, Ferenc

2018-05-01

The paper presents the detector system developed by Datalist Systems, Ltd. (previously ANTE Innovative Technologies) for the NEAT-II spectrometer at HZB. We present initial concept, design and implementation highlights as well as the first results of measurements such as position resolution. The initial concept called for modular architecture with 416 3He detector tubes organized into thirteen 32-tube modules that can be independently installed and removed to and from the detector vacuum chamber for ease of maintenance. The unalloyed aluminum mechanical support modules for four 8-tube units each also house the air-boxes that contain the front-end electronics (preamplifiers) that need to be on atmospheric pressure. The modules have been manufactured and partly assembled in Hungary and then fully assembled and installed on site by Datalist Systems crew. The signal processing and data acquisition solution is based on low time constant (˜60 ns) preamplifier electronics and sampling ADC's running at 50 MS/s (i.e. a sample every 20 ns) for all 832 data channels. The preamplifiers are proprietary, developed specifically for the NEAT spectrometer, while the ADC's and the FPGA's that further process the data are based on National Instruments products. The data acquisition system comprises 26 FPGA modules each serving 16 tubes (providing for up to 50 kHz count rate per individual tube) and it is organized into two PXI chassis and two data acquisition computers that perform post-processing, event classification and provide appropriate preview of the collected data. The data acquisition software based on Event Recording principles provides a single point of contact for the scientific software with an Event Record List with absolute timestamps of 100ns resolution, timing data of 100 ns resolution for the seven discs chopper system as well as classification data that can be used for flexible data filtering in off-line analysis of the gathered data. A unique 3-tier system of filtering criteria of events is in operation: a hard threshold in the FPGA's to reduce the effect of noise, a pulse-shape based classification to eliminate gamma sensitivity and an additional flexible feature based classification to filter out pileup and other unwanted phenomena. This ensures high count rates (50kHz per tube, 1MHz overall) while maintaining good quality of measurements (e.g. position resolution). The first measurement results show that the delivered detector system meets the initial requirements of 20 mm position resolution along the 2000mm long detector tubes. This is partly due to the innovative event classification system that provides vital pulse shape data that can be used for sophisticated position resolution algorithms implemented on the DAQ computers.

Simulation of Silicon Photomultiplier Signals

NASA Astrophysics Data System (ADS)

Seifert, Stefan; van Dam, Herman T.; Huizenga, Jan; Vinke, Ruud; Dendooven, Peter; Lohner, Herbert; Schaart, Dennis R.

2009-12-01

In a silicon photomultiplier (SiPM), also referred to as multi-pixel photon counter (MPPC), many Geiger-mode avalanche photodiodes (GM-APDs) are connected in parallel so as to combine the photon counting capabilities of each of these so-called microcells into a proportional light sensor. The discharge of a single microcell is relatively well understood and electronic models exist to simulate this process. In this paper we introduce an extended model that is able to simulate the simultaneous discharge of multiple cells. This model is used to predict the SiPM signal in response to fast light pulses as a function of the number of fired cells, taking into account the influence of the input impedance of the SiPM preamplifier. The model predicts that the electronic signal is not proportional to the number of fired cells if the preamplifier input impedance is not zero. This effect becomes more important for SiPMs with lower parasitic capacitance (which otherwise is a favorable property). The model is validated by comparing its predictions to experimental data obtained with two different SiPMs (Hamamatsu S10362-11-25u and Hamamatsu S10362-33-25c) illuminated with ps laser pulses. The experimental results are in good agreement with the model predictions.

Computed Fixed Beam Horizontal Coverage as Related to Redundancy in the AN/SQS-26CX Sonar Equipment

DTIC Science & Technology

1964-12-21

signal, either from the transducer element in transmit, A_ or the preamplifier in receive, no matter which stave subassembly is defective. 3...100 00 100 200 300 400 400 x- -500 X4 -9 PASIV ARA N.1 -eo 1ɘ 8 72 7 6 2 4 2 B25 -RCO~c DWG.A74 -II CONFIDE NTIAL AUSTON, TEXAS 32/4SKC CONFIDENTIAL

Unmanned Aerial Vehicle-Mounted High Sensitivity RF Receiver to Detect Improvised Explosive Devices

DTIC Science & Technology

2007-09-01

12 C. PREAMPLIFIER ......................................13 D. RECEIVER...discussed further in Chapter III. Figure 5. LPY41 log periodic antenna. (From Ramsey Elctronics) C. PREAMPLIFIER After the signal passes through...the Antenna, it enters the preamplifier . When dealing with unintentional signals which may be as low as -160dB, it is essential to have a low noise

Photocurrent Measurement of PC and PV HgCdTe Detectors

PubMed Central

Eppeldauer, George P.; Martin, Robert J.

2001-01-01

Novel preamplifiers for working standard photoconductive (PC) and photovoltaic (PV) HgCdTe detectors have been developed to maintain the spectral responsivity scale of the National Institute of Standards and Technology (NIST) in the wavelength range of 5 μm to 20 μm. The linear PC mode preamplifier does not need any compensating source to zero the effect of the detector bias current for the preamplifier output. The impedance multiplication concept with a positive feedback buffer amplifier was analyzed and utilized in a bootstrap PV transimpedance amplifier to measure photocurrent of a 200 Ω shunt resistance photodiode with a maximum signal gain of 108 V/A. In spite of the high performance lock-in used as a second-stage signal-amplifier, the signal-to-noise ratio had to be optimized for the output of the photocurrent preamplifiers. Noise and drift were equalized for the output of the PV mode preamplifier. The signal gain errors were calculated to determine the signal frequency range where photocurrent-to-voltage conversion can be performed with very low uncertainties. For the design of both PC and PV detector preamplifiers, the most important gain equations are described. Measurement results on signal ranges and noise performance are discussed. PMID:27500036

Photocurrent Measurement of PC and PV HgCdTe Detectors.

PubMed

Eppeldauer, G P; Martin, R J

2001-01-01

Novel preamplifiers for working standard photoconductive (PC) and photovoltaic (PV) HgCdTe detectors have been developed to maintain the spectral responsivity scale of the National Institute of Standards and Technology (NIST) in the wavelength range of 5 μm to 20 μm. The linear PC mode preamplifier does not need any compensating source to zero the effect of the detector bias current for the preamplifier output. The impedance multiplication concept with a positive feedback buffer amplifier was analyzed and utilized in a bootstrap PV transimpedance amplifier to measure photocurrent of a 200 Ω shunt resistance photodiode with a maximum signal gain of 10(8) V/A. In spite of the high performance lock-in used as a second-stage signal-amplifier, the signal-to-noise ratio had to be optimized for the output of the photocurrent preamplifiers. Noise and drift were equalized for the output of the PV mode preamplifier. The signal gain errors were calculated to determine the signal frequency range where photocurrent-to-voltage conversion can be performed with very low uncertainties. For the design of both PC and PV detector preamplifiers, the most important gain equations are described. Measurement results on signal ranges and noise performance are discussed.

Ultra-low-noise preamplifier for condenser microphones.

PubMed

Starecki, Tomasz

2010-12-01

The paper presents the design of a low-noise preamplifier dedicated for condenser measurement microphones used in high sensitivity applications, in which amplifier noise is the main factor limiting sensitivity of the measurements. In measurement microphone preamplifiers, the dominant source of noise at lower frequencies is the bias resistance of the input stage. In the presented solution, resistors were connected to the input stage by means of switches. The switches are opened during measurements, which disconnects the resistors from the input stage and results in noise reduction. Closing the switches allows for fast charging of the microphone capacitance. At low frequencies the noise of the designed preamplifier is a few times lower in comparison to similar, commercially available instruments.

Room air monitor for radioactive aerosols

DOEpatents

Balmer, D.K.; Tyree, W.H.

1987-03-23

A housing assembly for use with a room air monitor for simultaneous collection and counting of suspended particles includes a casing containing a combination detector-preamplifier system at one end, a filter system at the other end, and an air flow system consisting of an air inlet formed in the casing between the detector-preamplifier system and the filter system and an air passageway extending from the air inlet through the casing and out the end opposite the detector-preamplifier combination. The filter system collects suspended particles transported directly through the housing by means of the air flow system, and these particles are detected and examined for radioactivity by the detector-preamplifier combination. 2 figs.

A 1-2 GHz pulsed and continuous wave electron paramagnetic resonance spectrometer

NASA Astrophysics Data System (ADS)

Quine, Richard W.; Rinard, George A.; Ghim, Barnard T.; Eaton, Sandra S.; Eaton, Gareth R.

1996-07-01

A microwave bridge has been constructed that performs three types of electron paramagnetic resonance experiments: continuous wave, pulsed saturation recovery, and pulsed electron spin echo. Switching between experiment types can be accomplished via front-panel switches without moving the sample. Design features and performance of the bridge and of a resonator used in testing the bridge are described. The bridge is constructed of coaxial components connected with semirigid cable. Particular attention has been paid to low-noise design of the preamplifier and stability of automatic frequency control circuits. The bridge incorporates a Smith chart display and phase adjustment meter for ease of tuning.

The front-end electronics and slow control of large area SiPM for the SST-1M camera developed for the CTA experiment

NASA Astrophysics Data System (ADS)

Aguilar, J. A.; Bilnik, W.; Borkowski, J.; Cadoux, F.; Christov, A.; della Volpe, D.; Favre, Y.; Heller, M.; Kasperek, J.; Lyard, E.; Marszałek, A.; Moderski, R.; Montaruli, T.; Porcelli, A.; Prandini, E.; Rajda, P.; Rameez, M.; Schioppa, E.; Troyano Pujadas, I.; Ziȩtara, K.; Błocki, J.; Bogacz, L.; Bulik, T.; Curyło, M.; Dyrda, M.; Frankowski, A.; Grudniki, Ł.; Grudzińska, M.; Idźkowski, B.; Jamrozy, M.; Janiak, M.; Lalik, K.; Mach, E.; Mandat, D.; Michałowski, J.; Neronov, A.; Niemiec, J.; Ostrowski, M.; Paśsko, P.; Pech, M.; Schovanek, P.; Seweryn, K.; Skowron, K.; Sliusar, V.; Sowiński, M.; Stawarz, Ł.; Stodulska, M.; Stodulski, M.; Toscano, S.; Walter, R.; Wiȩcek, M.; Zagdański, A.; Żychowski, P.

2016-09-01

The single mirror Small Size Telescope (SST-1M) is one of the proposed designs for the smallest type of telescopes, SSTs that will compose the Cherenkov Telescope Array (CTA). The SST-1M camera will use Silicon PhotoMultipliers (SiPM) which are nowadays commonly used in High Energy Physics experiments and many imaging applications. However the unique pixel shape and size have required a dedicated development by the University of Geneva and Hamamatsu. The resulting sensor has a surface of ∼94 mm2 and a total capacitance of ∼3.4 nF. These unique characteristics, combined with the stringent requirements of the CTA project on timing and charge resolution have led the University of Geneva to develop custom front-end electronics. The preamplifier stage has been tailored in order to optimize the signal shape using measurement campaigns and electronic simulation of the sensor. A dedicated trans-impedance pre-amplifier topology is used resulting in a power consumption of 400 mW per pixel and a pulse width < 30 ns. The measurements that have led to the choice of the different components and the resulting performance are detailed in this paper. The slow control electronics was designed to provide the bias voltage with 6.7 mV precision and to correct for temperature variation with a forward feedback compensation with 0.17 °C resolution. It is fully configurable and can be monitored using CANbus interface. The architecture and the characterization of the various elements are presented.

Coastal Surveillance

DTIC Science & Technology

1980-04-01

testing of sonobuoys, an analysis of expected important factors can be made. Using the passive- sonar ’ equation: SL - TL - NL - 01 DT Source...circuitry have been removed or disabled and 2) the input stage has been modified to adapt a different hydrophone/ preamplifier to the system, 3) in two...ground and high lead which is carrying both audio up and power down to the preamplifier . The drain load resistor for the F.E.T. preamplifier is on the

Performance Evaluation of a Prototype Underwater Short-Range Acoustic Telemetry Modem

DTIC Science & Technology

2010-09-01

SR560 Low-Noise Preamplifier – Hewlett Packard (HP) 3314A Function Generator – Phillips PM 3384 Oscilloscope – Dell Latitude D620 notebook...two Stanford Research Systems SR560 low-noise preamplifiers , an IOtech Personal DAQ/3000 Series data acquisition box (DAQ), an HP 3314A function...mono frequency measurements were two B&K 8103 hydrophones, two Stanford Research Systems SR560 low-noise preamplifiers , an IOtech Personal DAQ/3000

Front-end circuit for position sensitive silicon and vacuum tube photomultipliers with gain control and depth of interaction measurement

NASA Astrophysics Data System (ADS)

Herrero, Vicente; Colom, Ricardo; Gadea, Rafael; Lerche, Christoph W.; Cerdá, Joaquín; Sebastiá, Ángel; Benlloch, José M.

2007-06-01

Silicon Photomultipliers, though still under development for mass production, may be an alternative to traditional Vacuum Photomultipliers Tubes (VPMT). As a consequence, electronic front-ends initially designed for VPMT will need to be modified. In this simulation, an improved architecture is presented which is able to obtain impact position and depth of interaction of a gamma ray within a continuous scintillation crystal, using either kind of PM. A current sensitive preamplifier stage with individual gain adjustment interfaces the multi-anode PM outputs with a current division resistor network. The preamplifier stage allows to improve front-end processing delay and temporal resolution behavior as well as to increase impact position calculation resolution. Depth of interaction (DOI) is calculated from the width of the scintillation light distribution, which is related to the sum of voltages in resistor network input nodes. This operation is done by means of a high-speed current mode scheme.

A Portable Infrasonic Detection System

NASA Technical Reports Server (NTRS)

Shams, Qamar A.; Burkett, Cecil G.; Zuckerwar, Allan J.; Lawrenson, Christopher C.; Masterman, Michael

2008-01-01

During last couple of years, NASA Langley has designed and developed a portable infrasonic detection system which can be used to make useful infrasound measurements at a location where it was not possible previously. The system comprises an electret condenser microphone, having a 3-inch membrane diameter, and a small, compact windscreen. Electret-based technology offers the lowest possible background noise, because Johnson noise generated in the supporting electronics (preamplifier) is minimized. The microphone features a high membrane compliance with a large backchamber volume, a prepolarized backplane and a high impedance preamplifier located inside the backchamber. The windscreen, based on the high transmission coefficient of infrasound through matter, is made of a material having a low acoustic impedance and sufficiently thick wall to insure structural stability. Close-cell polyurethane foam has been found to serve the purpose well. In the proposed test, test parameters will be sensitivity, background noise, signal fidelity (harmonic distortion), and temporal stability. The design and results of the compact system, based upon laboratory and field experiments, will be presented.

Development of Nanomechanical Sensors for Breast Cancer Biomarkers

DTIC Science & Technology

2008-06-01

semiconductor industry in developing large scale integrated circuits at very lost cost can lead to similar breakthroughs in array sensors for biomolecules of...insulated from the serum or buffer. The entire device is mounted onto a semiconductor chip carrier, for easy integration with electronics. Figure 3...Keithley 2400 source meter. The ac modulation and the dc bias are added by a noninverting summing circuit, which is integrated with the preamplifier

A low noise single-transistor transimpedance preamplifier for Fourier-transform mass spectrometry using a T feedback network

PubMed Central

Lin, Tzu-Yung; Green, Roger J.; O’Connor, Peter B.

2012-01-01

A novel single-transistor transimpedance preamplifier has been introduced for improving performance in Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometry. A low noise junction field-effect transistor (JFET), BF862, is used as the main amplification stage of this trans-impedance preamplifier, and a T-shaped feedback network is introduced as both the feedback and the gate biasing solutions. The T feedback network has been studied using an operational amplifier (Op Amp), AD8099. Such a feedback system allows ∼100-fold less feedback resistance at a given transimpedance, hence preserving bandwidth, which is beneficial to applications demanding high gain. The single-transistor preamplifier yields a tested transimpedance of ∼104 Ω (80 dBΩ) in the frequency range between 1 kHz and 1 MHz (mass-to-charge ratio, m/z, of around 180-180k for a 12-T FT-ICR system), with a low power consumption of ∼6 mW, which implies that this preamplifier is well suited to a 12-T FT-ICR mass spectrometer. In trading noise performance for higher trans-impedance, an alternative preamplifier design, an AD8099 preamplifier with the T feedback network, has also been studied with a capability of ∼106 Ω (120 dBΩ) transimpedance in the same frequency range. The resistive components in the T feedback network reported here can be replaced by complex impedances, which allows adaptation of this feedback system to other frequency, transimpedance, and noise characteristics for applications not only in other mass spectrometers, such as Orbitrap, time-of-flight (TOF), and ion trap systems, but also in other charge/current detecting systems such as spectroscopy systems, microscopy systems, optical communication systems, or charge-coupled devices (CCDs). PMID:23020394

A low noise single-transistor transimpedance preamplifier for Fourier-transform mass spectrometry using a T feedback network.

PubMed

Lin, Tzu-Yung; Green, Roger J; O'Connor, Peter B

2012-09-01

A novel single-transistor transimpedance preamplifier has been introduced for improving performance in Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometry. A low noise junction field-effect transistor (JFET), BF862, is used as the main amplification stage of this trans-impedance preamplifier, and a T-shaped feedback network is introduced as both the feedback and the gate biasing solutions. The T feedback network has been studied using an operational amplifier (Op Amp), AD8099. Such a feedback system allows ~100-fold less feedback resistance at a given transimpedance, hence preserving bandwidth, which is beneficial to applications demanding high gain. The single-transistor preamplifier yields a tested transimpedance of ~10(4) Ω (80 dBΩ) in the frequency range between 1 kHz and 1 MHz (mass-to-charge ratio, m/z, of around 180-180k for a 12-T FT-ICR system), with a low power consumption of ~6 mW, which implies that this preamplifier is well suited to a 12-T FT-ICR mass spectrometer. In trading noise performance for higher trans-impedance, an alternative preamplifier design, an AD8099 preamplifier with the T feedback network, has also been studied with a capability of ~10(6) Ω (120 dBΩ) transimpedance in the same frequency range. The resistive components in the T feedback network reported here can be replaced by complex impedances, which allows adaptation of this feedback system to other frequency, transimpedance, and noise characteristics for applications not only in other mass spectrometers, such as Orbitrap, time-of-flight (TOF), and ion trap systems, but also in other charge/current detecting systems such as spectroscopy systems, microscopy systems, optical communication systems, or charge-coupled devices (CCDs).

Fast response pyroelectric detector-preamplifier assembled device

NASA Astrophysics Data System (ADS)

Bai, PiJi; Tai, Yunjian; Liu, Huiping

2008-03-01

The pyroelectric detector is wide used for its simple structure and high performance to price ratio. It has been used in thermal detecting, infrared spectrum and laser testing. When the pyroelectric detector was applied in practice, fast reponse speed is need. For improving the response speed of the pyroelectric detector some specific technology has been used in the preamplifier schematic. High sense and fast response character of the pyroelectric detector-preamplifier assembled device had been achieved. When the device is applied in acute concussion condition, it must survive from the acute concussion condition testing. For it reliability some specific technology was used in the device fabricating procedure. At last the performance parameter testing result and simulation application condition result given in this paper show the performance of the pyroelectric detector-preamplifier assembled device had achieved the advance goal.

Differential CMOS Sub-Terahertz Detector with Subthreshold Amplifier.

PubMed

Yang, Jong-Ryul; Han, Seong-Tae; Baek, Donghyun

2017-09-09

We propose a differential-type complementary metal-oxide-semiconductor (CMOS) sub-terahertz (THz) detector with a subthreshold preamplifier. The proposed detector improves the voltage responsivity and effective signal-to-noise ratio (SNR) using the subthreshold preamplifier, which is located between the differential detector device and main amplifier. The overall noise of the detector for the THz imaging system is reduced by the preamplifier because it diminishes the noise contribution of the main amplifier. The subthreshold preamplifier is self-biased by the output DC voltage of the detector core and has a dummy structure that cancels the DC offsets generated by the preamplifier itself. The 200 GHz detector fabricated using 0.25 μm CMOS technology includes a low drop-out regulator, current reference blocks, and an integrated antenna. A voltage responsivity of 2020 kV/W and noise equivalent power of 76 pW/√Hz are achieved using the detector at a gate bias of 0.5 V, respectively. The effective SNR at a 103 Hz chopping frequency is 70.9 dB with a 0.7 W/m² input signal power density. The dynamic range of the raster-scanned THz image is 44.59 dB.

Differential CMOS Sub-Terahertz Detector with Subthreshold Amplifier

PubMed Central

Han, Seong-Tae; Baek, Donghyun

2017-01-01

We propose a differential-type complementary metal-oxide-semiconductor (CMOS) sub-terahertz (THz) detector with a subthreshold preamplifier. The proposed detector improves the voltage responsivity and effective signal-to-noise ratio (SNR) using the subthreshold preamplifier, which is located between the differential detector device and main amplifier. The overall noise of the detector for the THz imaging system is reduced by the preamplifier because it diminishes the noise contribution of the main amplifier. The subthreshold preamplifier is self-biased by the output DC voltage of the detector core and has a dummy structure that cancels the DC offsets generated by the preamplifier itself. The 200 GHz detector fabricated using 0.25 μm CMOS technology includes a low drop-out regulator, current reference blocks, and an integrated antenna. A voltage responsivity of 2020 kV/W and noise equivalent power of 76 pW/√Hz are achieved using the detector at a gate bias of 0.5 V, respectively. The effective SNR at a 103 Hz chopping frequency is 70.9 dB with a 0.7 W/m2 input signal power density. The dynamic range of the raster-scanned THz image is 44.59 dB. PMID:28891927

Feasibility Study to Adapt the Microflown Vector Sensor for Underwater Use

DTIC Science & Technology

2012-12-01

properties were of less importance for this experiment. A calibrated ACO Pacific pressure microphone in combination with an ACO pacific 1/2” preamplifier ... preamplifier was used for amplification and filtering. Pre-amplification was set to 10x and a 1 kHz High pass and 100 kHz Low pass filter was used to reduce...Kjær Turntable system type 9640 Stanford RS preamplifier model SR560 Pre-amplification: 10x High pass filter: 1 kHz Low pass filter: 100 kHz

Light-Based Triggering and Reconstruction of Michel Electrons in LArIAT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foreman, W.

2016-01-19

The LArIAT Experiment aims to calibrate the liquid argon time projection chamber (LArTPC) using a beam of charged particles at the Fermilab Test Beam Facility. It is equipped with a novel scintillation light readout system using PMTs and custom SiPM preamplifier boards to detect light from reflector foils coated with wavelength-shifting TPB. A trigger on delayed secondary flashes of light captures events containing stopping cosmic muons together with the Michel electrons coming from their subsequent decay. This dedicated Michel trigger supplies an abundant sample of low-energy electrons throughout the detector's active volume, providing opportunities to study the combined calorimetric capabilitiesmore » of the light system and the TPC. Preliminary results using scintillation light to study properties of the Michel electron sample are presented.« less

Improved Performance Analysis of Free Space Optics Communication Link under Rain Conditions using EDFA Pre-amplifier

NASA Astrophysics Data System (ADS)

Singh, Mehtab

2018-04-01

Free Space Optics (FSO) also known as Optical Wireless Communication (OWC) is a communication technology in which free space/air is used as the propagation medium and optical signals are used as the information carriers. One of the most crucial factors which degrade the performance of FSO link is the signal attenuation due to different atmospheric weather conditions such as haze, rain, storm, and fog. In this paper, an improved performance analysis of a 2.5 Gbps FSO link under rain conditions has been reported using Erbium-Doped Fiber Amplifier (EDFA) as a pre-amplifier. The results show that the maximum link distance for an FSO link under rain weather conditions with acceptable performance levels (Q ˜6 and BER ≤ 10-9 in the absence of EDFA pre-amplifier is 1,250 m which increases to 1,675 m with the use of EDFA pre-amplifier.

PMF: The front end electronic of the ALFA detector

NASA Astrophysics Data System (ADS)

Barrillon, P.; Blin, S.; Cheikali, C.; Cuisy, D.; Gaspard, M.; Fournier, D.; Heller, M.; Iwanski, W.; Lavigne, B.; De la Taille, C.; Puzo, P.; Socha, J.-L.

2010-11-01

The front end electronic (PMF) of the future ATLAS luminometer is described here. It is composed of a MAPMT and a compact stack of three PCBs, which deliver high voltage, route and read out of the output signals. The third board contains an FPGA and MAROC, a 64-channel ASIC, which can correct the non-uniformity of the MAPMT channels gain, thanks to a variable gain preamplifier. Its main role is to shape and discriminate the input signals at 1/3 photo-electron and produce 64 trigger outputs. Laboratory tests performed on prototype and pre-series PMFs have showed performances in good agreement with the requirements and have fulfilled the approval criteria for the final production of all elements.

The Voyager Cosmic Ray Experiment

NASA Technical Reports Server (NTRS)

Stilwell, D. E.; Davis, W. D.; Joyce, R. M.; Mcdonald, F. B.; Trainor, J. H.; Althouse, W. E.; Cummings, A. C.; Garrard, T. L.; Stone, E. C.; Vogt, R. E.

1979-01-01

The Voyager Cosmic Ray Experiment includes seven dE/dx-E telescopes to measure the energy and charge of particles with atomic numbers from 1 to 26 in the energy range 1-500 MeV/nucleon and to measure electron energy in the range from 3 to 110 MeV. Isotopic composition of hydrogen through sulfur in the range up to 75 Mev/nucleon can also be resolved. The electronic systems include a dual-gain, charge sensitive preamplifier, 4096-channel pulse height analyzers for three parameter analysis of selected events, and an event type readout polling scheme to maximize the use of available telemetry space and to enhance the occurrence of rare events in the data. Details of the detector, electronic and mechanical design are presented.

Development of slew-rate-limited time-over-threshold (ToT) ASIC for a multi-channel silicon-based ion detector

NASA Astrophysics Data System (ADS)

Uenomachi, M.; Orita, T.; Shimazoe, K.; Takahashi, H.; Ikeda, H.; Tsujita, K.; Sekiba, D.

2018-01-01

High-resolution Elastic Recoil Detection Analysis (HERDA), which consists of a 90o sector magnetic spectrometer and a position-sensitive detector (PSD), is a method of quantitative hydrogen analysis. In order to increase sensitivity, a HERDA system using a multi-channel silicon-based ion detector has been developed. Here, as a parallel and fast readout circuit from a multi-channel silicon-based ion detector, a slew-rate-limited time-over-threshold (ToT) application-specific integrated circuit (ASIC) was designed, and a new slew-rate-limited ToT method is proposed. The designed ASIC has 48 channels and each channel consists of a preamplifier, a slew-rate-limited shaping amplifier, which makes ToT response linear, and a comparator. The measured equivalent noise charges (ENCs) of the preamplifier, the shaper, and the ToT on no detector capacitance were 253±21, 343±46, and 560±56 electrons RMS, respectively. The spectra from a 241Am source measured using a slew-rate-limited ToT ASIC are also reported.

A miniaturized neuroprosthesis suitable for implantation into the brain

NASA Technical Reports Server (NTRS)

Mojarradi, Mohammad; Binkley, David; Blalock, Benjamin; Andersen, Richard; Ulshoefer, Norbert; Johnson, Travis; Del Castillo, Linda

2003-01-01

This paper presents current research on a miniaturized neuroprosthesis suitable for implantation into the brain. The prosthesis is a heterogeneous integration of a 100-element microelectromechanical system (MEMS) electrode array, front-end complementary metal-oxide-semiconductor (CMOS) integrated circuit for neural signal preamplification, filtering, multiplexing and analog-to-digital conversion, and a second CMOS integrated circuit for wireless transmission of neural data and conditioning of wireless power. The prosthesis is intended for applications where neural signals are processed and decoded to permit the control of artificial or paralyzed limbs. This research, if successful, will allow implantation of the electronics into the brain, or subcutaneously on the skull, and eliminate all external signal and power wiring. The neuroprosthetic system design has strict size and power constraints with each of the front-end preamplifier channels fitting within the 400 x 400-microm pitch of the 100-element MEMS electrode array and power dissipation resulting in less than a 1 degree C temperature rise for the surrounding brain tissue. We describe the measured performance of initial micropower low-noise CMOS preamplifiers for the neuroprosthetic.

Performance of a laser microsatellite network with an optical preamplifier.

PubMed

Arnon, Shlomi

2005-04-01

Laser satellite communication (LSC) uses free space as a propagation medium for various applications, such as intersatellite communication or satellite networking. An LSC system includes a laser transmitter and an optical receiver. For communication to occur, the line of sight of the transmitter and the receiver must be aligned. However, mechanical vibration and electronic noise in the control system reduce alignment between the transmitter laser beam and the receiver field of view (FOV), which results in pointing errors. The outcome of pointing errors is fading of the received signal, which leads to impaired link performance. An LSC system is considered in which the optical preamplifier is incorporated into the receiver, and a bit error probability (BEP) model is derived that takes into account the statistics of the pointing error as well as the optical amplifier and communication system parameters. The model and the numerical calculation results indicate that random pointing errors of sigma(chi)2G > 0.05 penalize communication performance dramatically for all combinations of optical amplifier gains and noise figures that were calculated.

A Front-End electronics board for single photo-electron timing and charge from MaPMT

NASA Astrophysics Data System (ADS)

Giordano, F.; Breton, D.; Beigbeder, C.; De Robertis, G.; Fusco, P.; Gargano, F.; Liuzzi, R.; Loparco, F.; Mazziotta, M. N.; Rizzi, V.; Tocut, V.

2013-08-01

A Front-End (FE) design based on commercial operational amplifiers has been developed to read-out signals from a Multianode PhotoMultiplier Tube (MaPMT). The overall design has been optimised for single photo-electron signal from the Hamamatsu H8500. The signal is collected by a current sensitive preamplifier and then it is fed into both a ECL fast discriminator and a shaper for analog output readout in differential mode. The analog signal and the digital gates are then registered on VME ADC and TDC modules respectively. Performances in terms of linearity, gain and timing resolution will be discussed, presenting results obtained on a test bench with differentiated step voltage inputs and also with a prototype electronic board plugged into the H8500 PMT illuminated by a picosecond laser.

Performance measurement results for a 220 Mbps QPPM optical communication receiver with an EG/G Slik APD

NASA Technical Reports Server (NTRS)

Davidson, Frederic M.; Sun, Xiaoli

1992-01-01

The performance of a 220 Mbps quaternary pulse position modulation (QPPM) optical communication receiver with a 'Slik' silicon avalanche photodiode (APD) and a wideband transimpedance preamplifier in a small hybrid circuit module was measured. The receiver performance had been poor due to the lack of a wideband and low noise transimpedance preamplifier. With the new APB preamplifier module, the receiver achieved a bit error rate (BER) of 10 exp -6 at an average received input optical signal power of 4.2 nW, which corresponds to an average of 80 received (incident) signal photons per information bit.

Miniature electrometer preamplifier effectively compensates for input capacitance

NASA Technical Reports Server (NTRS)

Burrous, C. N.; Deboo, G. J.

1966-01-01

Negative capacitance preamplifier using a dual MOS /Metal Oxide Silicon/ transistor in conjunction with bipolar transistors is used with intracellular microelectrodes in recording bioelectric potentials. Applications would include use as a pickup plate video amplifier in storage tube tests and for pH and ionization chamber measurements.

Architecture of PAU survey camera readout electronics

NASA Astrophysics Data System (ADS)

Castilla, Javier; Cardiel-Sas, Laia; De Vicente, Juan; Illa, Joseph; Jimenez, Jorge; Maiorino, Marino; Martinez, Gustavo

2012-07-01

PAUCam is a new camera for studying the physics of the accelerating universe. The camera will consist of eighteen 2Kx4K HPK CCDs: sixteen for science and two for guiding. The camera will be installed at the prime focus of the WHT (William Herschel Telescope). In this contribution, the architecture of the readout electronics system is presented. Back- End and Front-End electronics are described. Back-End consists of clock, bias and video processing boards, mounted on Monsoon crates. The Front-End is based on patch panel boards. These boards are plugged outside the camera feed-through panel for signal distribution. Inside the camera, individual preamplifier boards plus kapton cable completes the path to connect to each CCD. The overall signal distribution and grounding scheme is shown in this paper.

Self-triggering readout system for the neutron lifetime experiment PENeLOPE

NASA Astrophysics Data System (ADS)

Gaisbauer, D.; Bai, Y.; Konorov, I.; Paul, S.; Steffen, D.

2016-02-01

PENeLOPE is a neutron lifetime measurement developed at the Technische Universität München and located at the Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II) aiming to achieve a precision of 0.1 seconds. The detector for PENeLOPE consists of about 1250 Avalanche Photodiodes (APDs) with a total active area of 1225 cm2. The decay proton detector and electronics will be operated at a high electrostatic potential of -30 kV and a magnetic field of 0.6 T. This includes shaper, preamplifier, ADC and FPGA cards. In addition, the APDs will be cooled to 77 K. The 1250 APDs are divided into 14 groups of 96 channels, including spares. A 12-bit ADC digitizes the detector signals with 1 MSps. A firmware was developed for the detector including a self-triggering readout with continuous pedestal calculation and configurable signal detection. The data transmission and configuration is done via the Switched Enabling Protocol (SEP). It is a time-division multiplexing low layer protocol which provides determined latency for time critical messages, IPBus, and JTAG interfaces. The network has a n:1 topology, reducing the number of optical links.

Performance of the Fully Digital FPGA-Based Front-End Electronics for the GALILEO Array

NASA Astrophysics Data System (ADS)

Barrientos, D.; Bellato, M.; Bazzacco, D.; Bortolato, D.; Cocconi, P.; Gadea, A.; González, V.; Gulmini, M.; Isocrate, R.; Mengoni, D.; Pullia, A.; Recchia, F.; Rosso, D.; Sanchis, E.; Toniolo, N.; Ur, C. A.; Valiente-Dobón, J. J.

2015-12-01

In this work we present the architecture and results of a fully digital Front End Electronics (FEE) read out system developed for the GALILEO array. The FEE system, developed in collaboration with the Advanced Gamma Tracking Array (AGATA) collaboration, is composed of three main blocks: preamplifiers, digitizers and preprocessing electronics. The slow control system contains a custom Linux driver, a dynamic library and a server implementing network services. This work presents the first results of the digital FEE system coupled with a GALILEO germanium detector, which has demonstrated the capability to achieve an energy resolution of 1.530/00 at an energy of 1.33 MeV, similar to the one obtained with a conventional analog system. While keeping a good performance in terms of energy resolution, digital electronics will allow to instrument the full GALILEO array with a versatile system with high integration and low power consumption and costs.

In-Line Wear Monitor

DTIC Science & Technology

1988-09-01

and is available for future use in designs with the power supply in the sensor if needed. 4.1 PREAMPLIFIER Two different preamplifier designs were high...30. Sensaor mounting orientetisms for vibratiom tests. 34 A 1/2 g sinewave scan was performed up to 3 kHz at a fairly slow rate (1 oc- tave/minute

A High Sensitivity Preamplifier for Quartz Tuning Forks in QEPAS (Quartz Enhanced PhotoAcoustic Spectroscopy) Applications

PubMed Central

Starecki, Tomasz

2017-01-01

All the preamplifiers dedicated for Quartz Enhanced PhotoAcoustic Spectroscopy (QEPAS) applications that have so far been reported in the literature have been based on operational amplifiers working in transimpedance configurations. Taking into consideration that QEPAS sensors are based on quartz tuning forks, and that quartz has a relatively high voltage constant and relatively low charge constant, it seems that a transimpedance amplifier is not an optimal solution. This paper describes the design of a quartz QEPAS sensor preamplifier, implemented with voltage amplifier configuration. Discussion of an electrical model of the circuit and preliminary measurements are presented. Both theoretical analysis and experiments show that use of the voltage configuration allows for a substantial increase of the output signal in comparison to the transimpedance circuit with the same tuning fork working in identical conditions. Assuming that the sensitivity of the QEPAS technique depends directly on the properties of the preamplifier, use of the voltage amplifier configuration should result in an increase of QEPAS sensitivity by one to two orders of magnitude. PMID:29099765

A High Sensitivity Preamplifier for Quartz Tuning Forks in QEPAS (Quartz Enhanced PhotoAcoustic Spectroscopy) Applications.

PubMed

Starecki, Tomasz; Wieczorek, Piotr Z

2017-11-03

All the preamplifiers dedicated for Quartz Enhanced PhotoAcoustic Spectroscopy (QEPAS) applications that have so far been reported in the literature have been based on operational amplifiers working in transimpedance configurations. Taking into consideration that QEPAS sensors are based on quartz tuning forks, and that quartz has a relatively high voltage constant and relatively low charge constant, it seems that a transimpedance amplifier is not an optimal solution. This paper describes the design of a quartz QEPAS sensor preamplifier, implemented with voltage amplifier configuration. Discussion of an electrical model of the circuit and preliminary measurements are presented. Both theoretical analysis and experiments show that use of the voltage configuration allows for a substantial increase of the output signal in comparison to the transimpedance circuit with the same tuning fork working in identical conditions. Assuming that the sensitivity of the QEPAS technique depends directly on the properties of the preamplifier, use of the voltage amplifier configuration should result in an increase of QEPAS sensitivity by one to two orders of magnitude.

Radiation detection system

DOEpatents

Riedel, Richard A [Knoxville, TN; Wintenberg, Alan L [Knoxville, TN; Clonts, Lloyd G [Knoxville, TN; Cooper, Ronald G [Oak Ridge, TN

2012-02-14

A preamplifier circuit for processing a signal provided by a radiation detector includes a transimpedance amplifier coupled to receive a current signal from a detector and generate a voltage signal at its output. A second amplification stage has an input coupled to an output of the transimpedance amplifier for providing an amplified voltage signal. Detector electronics include a preamplifier circuit having a first and second transimpedance amplifier coupled to receive a current signal from a first and second location on a detector, respectively, and generate a first and second voltage signal at respective outputs. A second amplification stage has an input coupled to an output of the transimpedance amplifiers for amplifying the first and said second voltage signals to provide first and second amplified voltage signals. A differential output stage is coupled to the second amplification stage for receiving the first and second amplified voltage signals and providing a pair of outputs from each of the first and second amplified voltage signals. Read out circuitry has an input coupled to receive both of the pair of outputs, the read out circuitry having structure for processing each of the pair of outputs, and providing a single digital output having a time-stamp therefrom.

Summaries of Papers Presented at the Picosecond Electronics and Optoelectronics Topical Meeting Held in Salt Lake City, Utah on March 8-10, 1989

DTIC Science & Technology

1989-12-31

High T, Superconducting ing (SCM) is an important new technique for high.speed Films and Devices, R. A. Buhrrrn, Cornell U. I review the cur...and detection with terning of high T, superconducting (HTS) thin films , with em- optical preamplifiers is discussed. (p. 2) phasis on the n!gh...frequency properties of HTS films and de- vices. (p. 14) 9:00 AM WA2 Picosecond Spatially Resolved Optical Detection of 11.00 AM Charge-Den3ity Modulation In

Ultralow-noise readout circuit with an avalanche photodiode: toward a photon-number-resolving detector.

PubMed

Tsujino, Kenji; Akiba, Makoto; Sasaki, Masahide

2007-03-01

The charge-integration readout circuit was fabricated to achieve an ultralow-noise preamplifier for photoelectrons generated in an avalanche photodiode with linear mode operation at 77 K. To reduce the various kinds of noise, the capacitive transimpedance amplifier was used and consisted of low-capacitance circuit elements that were cooled with liquid nitrogen. As a result, the readout noise is equal to 3.0 electrons averaged for a period of 40 ms. We discuss the requirements for avalanche photodiodes to achieve photon-number-resolving detectors below this noise level.

Measurement of minority-carrier drift mobility in solar cells using a modulated electron beam

NASA Technical Reports Server (NTRS)

Othmer, S.; Hopkins, M. A.

1980-01-01

A determination of diffusivity on solar cells is here reported which utilizes a one dimensional treatment of diffusion under sinusoidal excitation. An intensity-modulated beam of a scanning electron microscope was used as a source of excitation. The beam was injected into the rear of the cell, and the modulated component of the induced terminal current was recovered phase sensitively. A Faraday cup to measure the modulated component of beam current was mounted next to the sample, and connected to the same electronics. A step up transformer and preamplifier were mounted on the sample holder. Beam currents on the order of 400-pA were used in order to minimize effects of high injection. The beam voltage was 34-kV, and the cell bias was kept at 0-V.

Noise performance of 0.35-(mu)m SOI CMOS devices and micropower preamplifier following 63-MeV, 1-Mrad (Si) proton irradiation

NASA Technical Reports Server (NTRS)

Binkley, D. M.; Hopper, C. E.; Cressler, J. D.; Mojarradi, M. M.; Blalock, B. J.

2004-01-01

This paper presents measured noise for 0.35(mu)m, silicon-on-insulator devices and a micropower preamplifier following 63-MeV, 1-Mrad (Si) proton irradiation. Flicker noise voltage, important for gyros having low frequency output, increases less than 32% after irradiation.

Adaptive Noise Reduction Techniques for Airborne Acoustic Sensors

DTIC Science & Technology

2012-01-01

and Preamplifiers . . . . . . . . . . . . . . . . . . . . 16 3.3.2 Audio Recorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 iv 4...consuming less energy than active systems such as radar, lidar, or sonar [5]. Ground and marine-based acoustic arrays are currently employed in a variety of...factors for the performance of an airborne acoustic array. 3.3.1 Audio Microphones and Preamplifiers An audio microphone is a transducer that converts

Liquid helium-cooled MOSFET preamplifier for use with astronomical bolometer

NASA Technical Reports Server (NTRS)

Goebel, J. H.

1977-01-01

A liquid helium-cooled p-channel enhancement mode MOSFET, the 3N167, is found to have sufficiently low noise for use as a preamplifier with helium-cooled bolometers that are used in infrared astronomy. Its characteristics at 300, 77, and 4.2 K are presented. It is also shown to have useful application with certain photoconductive and photovoltaic infrared detectors.

SpectraCAM SPM: a camera system with high dynamic range for scientific and medical applications

NASA Astrophysics Data System (ADS)

Bhaskaran, S.; Baiko, D.; Lungu, G.; Pilon, M.; VanGorden, S.

2005-08-01

A scientific camera system having high dynamic range designed and manufactured by Thermo Electron for scientific and medical applications is presented. The newly developed CID820 image sensor with preamplifier-per-pixel technology is employed in this camera system. The 4 Mega-pixel imaging sensor has a raw dynamic range of 82dB. Each high-transparent pixel is based on a preamplifier-per-pixel architecture and contains two photogates for non-destructive readout of the photon-generated charge (NDRO). Readout is achieved via parallel row processing with on-chip correlated double sampling (CDS). The imager is capable of true random pixel access with a maximum operating speed of 4MHz. The camera controller consists of a custom camera signal processor (CSP) with an integrated 16-bit A/D converter and a PowerPC-based CPU running a Linux embedded operating system. The imager is cooled to -40C via three-stage cooler to minimize dark current. The camera housing is sealed and is designed to maintain the CID820 imager in the evacuated chamber for at least 5 years. Thermo Electron has also developed custom software and firmware to drive the SpectraCAM SPM camera. Included in this firmware package is the new Extreme DRTM algorithm that is designed to extend the effective dynamic range of the camera by several orders of magnitude up to 32-bit dynamic range. The RACID Exposure graphical user interface image analysis software runs on a standard PC that is connected to the camera via Gigabit Ethernet.

Charge Loss and Charge Sharing Measurements for Two Different Pixelated Cadmium-Zinc-Telluride Detectors

NASA Technical Reports Server (NTRS)

Gaskin, Jessica; Sharma, Dharma; Ramsey, Brian; Seller, Paul

2003-01-01

As part of ongoing research at Marshall Space Flight Center, Cadmium-Zinc- Telluride (CdZnTe) pixilated detectors are being developed for use at the focal plane of the High Energy Replicated Optics (HERO) telescope. HERO requires a 64x64 pixel array with a spatial resolution of around 200 microns (with a 6m focal length) and high energy resolution (< 2% at 60keV). We are currently testing smaller arrays as a necessary first step towards this goal. In this presentation, we compare charge sharing and charge loss measurements between two devices that differ both electronically and geometrically. The first device consists of a 1-mm-thick piece of CdZnTe that is sputtered with a 4x4 array of pixels with pixel pitch of 750 microns (inter-pixel gap is 100 microns). The signal is read out using discrete ultra-low-noise preamplifiers, one for each of the 16 pixels. The second detector consists of a 2-mm-thick piece of CdZnTe that is sputtered with a 16x16 array of pixels with a pixel pitch of 300 microns (inter-pixel gap is 50 microns). Instead of using discrete preamplifiers, the crystal is bonded to an ASIC that provides all of the front-end electronics to each of the 256 pixels. what degree the bias voltage (i.e. the electric field) and hence the drift and diffusion coefficients affect our measurements. Further, we compare the measured results with simulated results and discuss to

A Low noise, Non-contact Capacitive Cardiac Sensor*

PubMed Central

Peng, GuoChen; Bocko, Mark F.

2014-01-01

The development of sensitive, non-contact electric field sensors to measure weak bioelectric signals will be useful for the development of a number of unobtrusive health sensors. In this paper we summarize our recent work on a number of specific challenges in the development of non-contact ECG sensors. First, we considered the design of a low noise sensor preamplifier. We have adapted circuit designs that incorporate a double feedback loop to cancel the input transistor leakage current while providing stable operation, fast settling time and good low frequency response without the need for ultrahigh value resistors. The measured input referred noise of the preamplifier in the frequency band 0.05–100 Hz is 0.76 μVrms, which is several times lower than existing ECG preamplifiers. PMID:23367049

An Analysis on a Dynamic Amplifier and Calibration Methods for a Pseudo-Differential Dynamic Comparator

NASA Astrophysics Data System (ADS)

Paik, Daehwa; Miyahara, Masaya; Matsuzawa, Akira

This paper analyzes a pseudo-differential dynamic comparator with a dynamic pre-amplifier. The transient gain of a dynamic pre-amplifier is derived and applied to equations of the thermal noise and the regeneration time of a comparator. This analysis enhances understanding of the roles of transistor's parameters in pre-amplifier's gain. Based on the calculated gain, two calibration methods are also analyzed. One is calibration of a load capacitance and the other is calibration of a bypass current. The analysis helps designers' estimation for the accuracy of calibration, dead-zone of a comparator with a calibration circuit, and the influence of PVT variation. The analyzed comparator uses 90-nm CMOS technology as an example and each estimation is compared with simulation results.

A low noise, non-contact capacitive cardiac sensor.

PubMed

Peng, GuoChen; Bocko, Mark F

2012-01-01

The development of sensitive, non-contact electric field sensors to measure weak bioelectric signals will be useful for the development of a number of unobtrusive health sensors. In this paper we summarize our recent work on a number of specific challenges in the development of non-contact ECG sensors. First, we considered the design of a low noise sensor preamplifier. We have adapted circuit designs that incorporate a double feedback loop to cancel the input transistor leakage current while providing stable operation, fast settling time and good low frequency response without the need for ultrahigh value resistors. The measured input referred noise of the preamplifier in the frequency band 0.05-100 Hz is 0.76 µV(rms), which is several times lower than existing ECG preamplifiers.

A transducer for bottom-scattering measurements

NASA Astrophysics Data System (ADS)

Tims, A. C.; Henriquez, T. A.; Williams, J. G.

1985-12-01

An omnidirectional 25-kHz transducer has been designed for use in bottom-scattering measurements. The transducer can be used either as a projector or, when fitted with a preamplifier, as a hydrophone. The requirements for the design are presented and solved with mathematical modeling and analysis. A comparison between theory and measured performance is given. The design of a low-noise preamplifier with integrated circuits is described.

Adaptive Sampling in Autonomous Marine Sensor Networks

DTIC Science & Technology

2006-06-01

Analog Processing Section A high-performance preamplifier with low noise characteristics is vital to obtaining quality sonar data. The preamplifier ...research assistantships through the Generic Ocean Array Technology Sonar (GOATS) project, contract N00014-97-1-0202 and contract N00014-05-G-0106 Delivery...Formation Behavior ..................................... 60 5 An AUV Intelligent Sensor for Real-Time Adaptive Sensing 63 5.1 A Logical Sonar Sensor

Digital pulse processing and electronic noise analysis for improving energy resolutions in planar TlBr detectors

NASA Astrophysics Data System (ADS)

Tada, Tsutomu; Hitomi, Keitaro; Tanaka, Tomonobu; Wu, Yan; Kim, Seong-Yun; Yamazaki, Hiromichi; Ishii, Keizo

2011-05-01

Digital pulse processing and electronic noise analysis are proposed for improving energy resolution in planar thallium bromide (TlBr) detectors. An energy resolution of 5.8% FWHM at 662 keV was obtained from a 0.5 mm thick planar TlBr detector at room temperature using a digitizer with a sampling rate of 100 MS/s and 8 bit resolution. The electronic noise in the detector-preamplifier system was measured as a function of pulse shaping time in order to investigate the optimum shaping time for the detector. The depth of interaction (DOI) in TlBr detectors for incident gamma-rays was determined by taking the ratio of pulse heights for fast-shaped to slow-shaped signals. FWHM energy resolution of the detector was improved from 5.8% to 4.2% by implementing depth correction and by using the obtained optimum shaping time.

High sensitivity cascaded preamplifier with an optical bridge structure in Brillouin distributed fiber sensing system

NASA Astrophysics Data System (ADS)

Bi, Weihong; Lin, Hang; Fu, Xinghu; Fu, Guangwei

2013-12-01

Fiber amplifiers such as Erbium-doped fiber amplifier (EDFA) played a key role in developing long-haul transmission system and have been an important element for enabling the development of optical communication system. EDFA amplifies the optical signal directly, without the optical-electric-optical switch and has the advantages such as high gain, broad band, low noise figure. It is widely used in repeaterless submarine system, smart grid and community antenna television system. This article describe the application of optical-fiber amplifiers in distributed optical fiber sensing system, focusing on erbium-doped fiber preamplifiers in modern transmission optical systems. To enhance the measurement range of a spontaneous Brillouin intensity based distributed fiber optical sensor and improve the receiver sensitivity, a two cascaded EDFAs C-band preamplifier with an optical bridge structure is proposed in this paper. The first cascaded EDFA is consisted of a length of 4.3m erbium-doped fiber and pumped in a forward pump light using a laser operating at 975nm. The second one made by using a length of 16m erbium-doped fiber is pumped in a forward pump light which is the remnant pump light of the first cascaded EDFA. At the preamplifier output, DWDM, centered at the signal wavelength, is used to suppress unwanted amplified spontaneous emission. The experimental results show that the two cascade preamplifier with a bridge structure can be used to amplify for input Brillouin backscattering light greater than about -43dBm. The optical gain is characterized and more than 26dB is obtained at 1549.50nm with 300mW pump power.

Mini-O, simple Omega receiver hardware for user education

NASA Technical Reports Server (NTRS)

Burhans, R. W.

1976-01-01

A problem with the Omega system is a lack of suitable low cost hardware for the small user community. A collection of do it yourself circuit modules are under development intended for use by educational institutions, small boat owners, aviation enthusiasts, and others who have some skills in fabricating their own electronic equipment. Applications of the hardware to time frequency standards measurements, signal propagation monitoring, and navigation experiments are presented. A family of Mini-O systems have been constructed varying from the simplest RF preamplifiers and narrowband filters front-ends, to sophisticated microcomputer interface adapters.

Binary selectable detector holdoff circuit: Design, testing, and application. [to laser radar data acquisition system

NASA Technical Reports Server (NTRS)

Kadrmas, K. A.

1973-01-01

A very high speed switching circuit, part of a laser radar data acquisition system, has been designed and tested. The primary function of this circuit was to provide computer controlled switching of photodiode detector preamplifier power supply voltages, typically less than plus or minus 20 volts, in approximately 10 nanoseconds. Thus, in actual use, detector and/or detector preamplifier damage can be avoided as a result of sudden extremely large values of backscattered radiation being detected, such as might be due to short range, very thin atmospheric dust layers. Switching of the power supply voltages was chosen over direct switching the photodiode detector input to the preamplifier, based on system noise considerations. Also, the circuit provides a synchronized trigger pulse output for triggering devices such as the Biomation Model 8100 100 MHz analog to digital converter.

Room air monitor for radioactive aerosols

DOEpatents

Balmer, David K.; Tyree, William H.

1989-04-11

A housing assembly for use with a room air monitor for simultaneous collection and counting of suspended particles includes a casing containing a combination detector-preamplifier system at one end, a filter system at the other end, and an air flow system consisting of an air inlet formed in the casing between the detector-preamplifier system and the filter system and an air passageway extending from the air inlet through the casing and out the end opposite the detector-preamplifier combination. The filter system collects suspended particles transported directly through the housing by means of the air flow system, and these particles are detected and examined for radioactivity by the detector-pre The U.S. Government has rights in this invention pursuant to Contract No. DE-AC04-76DP03533 between the Department of Energy and Rockwell International Corporation.

First signal from a broadband cryogenic preamplifier cooled by circulating liquid nitrogen in a 7 T Fourier transform ion cyclotron resonance mass spectrometer.

PubMed

Choi, Myoung Choul; Lee, Jeong Min; Lee, Se Gyu; Choi, Sang Hwan; Choi, Yeon Suk; Lee, Kyung Jae; Kim, SeungYong; Kim, Hyun Sik; Stahl, Stefan

2012-12-18

Despite the outstanding performance of Fourier transform ion cyclotron/mass spectrometry (FTICR/MS), the complexity of the cellular proteome or natural compounds presents considerable challenges. Sensitivity is a key performance parameter of a FTICR mass spectrometer. By improving this parameter, the dynamic range of the instrument can be increased to improve the detection signal of low-abundance compounds or fragment ion peaks. In order to improve sensitivity, a cryogenic detection system was developed by the KBSI (Korean Basic Science Institute) in collaboration with Stahl-Electronics (Mettenheim, Germany). A simple, efficient liquid circulation cooling system was designed and a cryogenic preamplifier implemented inside a FTICR mass spectrometer. This cooling system circulates a cryoliquid from a Dewar to the "liquid circulation unit" through a CF flange to cool a copper block and a cryopreamplifier; the cooling medium is subsequently exhausted into the air. The cryopreamplifier can be operated over a very wide temperature range, from room temperature to low temperature environments (4.2 K). First, ion signals detected by the cryopreamplifier using a circulating liquid nitrogen cooling system were observed and showed a signal-to-noise ratio (S/N) about 130% better than that obtained at room temperature.

The Forward Endcap of the Electromagnetic Calorimeter for the PANDA Detector at FAIR

NASA Astrophysics Data System (ADS)

Albrecht, Malte; PANDA Collaboration

2015-02-01

The versatile 4π-detector PANDA will be built at the Facility for Antiproton and Ion Research (FAIR), an accelerator complex, currently under construction near Darmstadt, Germany. A cooled antiproton beam in a momentum range of 1.5 - 15GeV/c will be provided by the High Energy Storage Ring (HESR). All measurements at PANDA rely on an excellent performance of the detector with respect to tracking, particle identification and energy measurement. The electromagnetic calorimeter (EMC) of the PANDA detector will be equipped with 15744 PbWO4 crystals (PWO-II), which will be operated at a temperature of - 25° C in order to increase the light output. The design of the forward endcap of the EMC has been finalized. The crystals will be read out with Large Area Avalanche Photo Diodes (LAAPDs) in the outer regions and with Vacuum Photo Tetrodes (VPTTs) in the innermost part. Production of photosensor units utilizing charge integrating preamplifiers has begun. A prototype comprised of 216 PbWO4 crystals has been built and tested at various accelerators (CERN SPS, ELSA/Bonn, MAMI/Mainz), where the crystals have been exposed to electron and photon beams of 25MeV up to 15GeV. The results of these test measurements regarding the energy and position resolution are presented.

A front-end read out chip for the OPERA scintillator tracker

NASA Astrophysics Data System (ADS)

Lucotte, A.; Bondil, S.; Borer, K.; Campagne, J. E.; Cazes, A.; Hess, M.; de La Taille, C.; Martin-Chassard, G.; Raux, L.; Repellin, J. P.

2004-04-01

Multi-anode photomultipliers H7546 are used to readout signal from the OPERA Scintillator Tracker (CERN/SPSC 2000-028, SPSC/P318, LNGSP 25/2000; CERN/SPSC 2001-025, SPSC/M668, LNGS-EXP30/2001). A 32-channel front-end Read Out Chip prototype accommodating the H7546 has been designed at LAL. This device features a low-noise, variable gain preamplifier to correct for multi-anode non-uniformity, an auto-trigger capability 100% efficient at a 0.3 photo-electron, and a charge measurement extending over a large dynamic range [0-100] photo-electrons. In this article we describe the ASIC architecture that is being implemented for the Target Tracker in OPERA, with a special emphasis put on the designs and the measured performance.

Mine Sweeping System for Magnetic and Non-Magnetic Mines.

DTIC Science & Technology

1994-12-29

be detected. One example of the latter type of system is a conventional sonar device wherein a directional beam of acoustic energy periodically...Although satisfactory for many uses, sonar devices have several inherent limitations. Nearby objects can cause echoes and these may obscure the echo of...electromagnetic signal and sends it to the preamplifier 601. The preamplifier 601 increases the strength of the received electrical signal before sending it

A new high dynamic range ROIC with smart light intensity control unit

NASA Astrophysics Data System (ADS)

Yazici, Melik; Ceylan, Omer; Shafique, Atia; Abbasi, Shahbaz; Galioglu, Arman; Gurbuz, Yasar

2017-05-01

This journal presents a new high dynamic range ROIC with smart pixel which consists of two pre-amplifiers that are controlled by a circuit inside the pixel. Each pixel automatically decides which pre-amplifier is used according to the incoming illumination level. Instead of using single pre-amplifier, two input pre-amplifiers, which are optimized for different signal levels, are placed inside each pixel. The smart circuit mechanism, which decides the best input circuit according to the incoming light level, is also designed for each pixel. In short, an individual pixel has the ability to select the best input amplifier circuit that performs the best/highest SNR for the incoming signal level. A 32 × 32 ROIC prototype chip is designed to demonstrate the concept in 0.18 μ m CMOS technology. The prototype is optimized for NIR and SWIR bands. Instead of a detector, process variation optimized current sources are placed inside the ROIC. The chip achieves minimum 8.6 e- input referred noise and 98.9 dB dynamic range. It has the highest dynamic range in the literature in terms of analog ROICs for SWIR band. It is operating in room temperature and power consumption is 2.8 μ W per pixel.

Front-end electronics for PWO-based PHOS calorimeter of ALICE

NASA Astrophysics Data System (ADS)

Muller, Hans; Budnikov, Dmitry; Ippolitov, Mikhail; Li, Qingxia; Manko, Vladislav; Pimenta, Rui; Rohrich, Dieter; Sibiryak, Iouri; Skaali, Bernhard; Vinogradov, Alexandre

2006-11-01

The electromagnetic Photon Spectrometer (PHOS) of ALICE consists of five modules with 56×64 PWO crystals, operated at -25 °C. Glued to each crystal are APD diodes which amplify a lightyield of 4.4 photoelectrons/MeV, followed by charge-sensitive pre-amplifiers with a charge conversion gain of ca. 1 V/pC. We describe our new 32-channel shaper/digitizer and readout electronics for gain-programmable photodiodes. These Front-End Electronics (FEE) cards are installed below the crystals in an isolated warm volume in geometrical correspondence to 2×16 crystal rows per card. With a total detector capacitance of 100 pF and a noise level of 3 MeV, the FEEs cover a 14 bit dynamic range from 5 MeV to 80 GeV. The low noise level is achieved by operating the APDs and preamplifiers at low temperature and by applying a relatively long shaping time of 1 μs. The offline timing resolution, obtained via a Gamma-2 fit is less than 2 ns. The second-order, dual-gain shapers produce semi-Gaussian output for 10 bit ADCs with embedded multi-event buffers. A Readout Control Unit (RCU) masters data readout with address-mapped access to the event-buffers and controls registers via a custom bus which interconnects up to 14 FEE cards. Programmable bias voltage controllers on the FEE cards allow for very precise gain adjustment of each individual APD. Being co-designed with the TRU trigger cards, each FEE card generates eight fast signal sums (2×2 crystals) as input to the TRU. FPGA-based algorithms generate level-0 and level-1 trigger decisions at 40 MHz and allow PHOS also to operate in self-triggered mode. Inside each PHOS module there are 112 FEE and 8 TRU cards which dissipate ca. 1 kW heat which is extracted via a water cooling system.

Fiber-Optic Communications Systems,

DTIC Science & Technology

1983-12-15

inherent noise level and a large dynamic diapason. Usually, an amplifier with reverse reaction, which is composed of a preamplifier and wide band amplifier...which are attached to a preamplifier on the base of an FET transistor and has an amplification of of around of 20 dB, an adaptation part and a low...systems are used to connect anti-submarine sonar to computers for signal processing. One such transmission line can connect 52 parallel channels with a

A 1microW 85nV/ radicalHz pseudo open-loop preamplifier with programmable band-pass filter for neural interface system.

PubMed

Chang, Sun-Il; Yoon, Euisik

2009-01-01

We report an energy efficient pseudo open-loop amplifier with programmable band-pass filter developed for neural interface systems. The proposed amplifier consumes 400nA at 2.5V power supply. The measured thermal noise level is 85nV/ radicalHz and input-referred noise is 1.69microV(rms) from 0.3Hz to 1 kHz. The amplifier has a noise efficiency factor of 2.43, the lowest in the differential topologies reported up to date to our knowledge. By programming the switched-capacitor frequency and bias current, we could control the bandwidth of the preamplifier from 138 mHz to 2.2 kHz to meet various application requirements. The entire preamplifier including band-pass filters has been realized in a small area of 0.043mm(2) using a 0.25microm CMOS technology.

A front-end readout mixed chip for high-efficiency small animal PET imaging

NASA Astrophysics Data System (ADS)

Ollivier-Henry, N.; Berst, J. D.; Colledani, C.; Hu-Guo, Ch.; Mbow, N. A.; Staub, D.; Guyonnet, J. L.; Hu, Y.

2007-02-01

Today, the main challenge of Positron Emission Tomography (PET) systems dedicated to small animal imaging is to obtain high detection efficiency and a highly accurate localization of radioisotopes. If we focus only on the PET characteristics such as the spatial resolution, its accuracy depends on the design of detector and on the electronics readout system as well. In this paper, we present a new design of such readout system with full custom submicrometer CMOS implementation. The front end chip consists of two main blocks from which the energy information and the time stamp with subnanosecond resolution can be obtained. In our A Multi-Modality Imaging System for Small Animal (AMISSA) PET system design, a matrix of LYSO crystals has to be read at each end by a 64 channels multianode photomultiplier tube. A specific readout electronic has been developed at the Hubert Curien Multidisciplinary Institute (IPHC, France). The architecture of this readout for the energy information detection is composed of a low-noise preamplifier, a CR-RC shaper and an analogue memory. In order to obtain the required dynamic range from 15 to 650 photoelectrons with good linearity, a current mode approach has been chosen for the preamplifier. To detect the signal with a temporal resolution of 1 ns, a comparator with a very low threshold (˜0.3 photoelectron) has been implemented. It gives the time reference of arrival signal coming from the detector. In order to obtain the time coincidence with a temporal resolution of 1 ns, a Time-to-Digital Converter (TDC) based on a Delay-Locked-Loop (DLL) has been designed. The chip is fabricated with AMS 0.35 μm process. The ASIC architecture and some simulation results will be presented in the paper.

Amping it up on a small budget: Transforming inexpensive, commercial audio and video components into a useful charged particle spectrometer

NASA Astrophysics Data System (ADS)

Pallone, Arthur

Necessity often leads to inspiration. Such was the case when a traditional amplifier quit working during the collection of an alpha particle spectrum. I had a 15 battery-powered audio amplifier in my box of project electronics so I connected it between the preamplifier and the multichannel analyzer. The alpha particle spectrum that appeared on the computer screen matched expectations even without correcting for impedance mismatches. Encouraged by this outcome, I have begun to systematically replace each of the parts in a traditional charged particle spectrometer with audio and video components available through consumer electronics stores with the goal of producing an inexpensive charged particle spectrometer for use in education and research. Hopefully my successes, setbacks, and results to date described in this presentation will inform and inspire others.

Status report of the GERDA experiment phase I

NASA Astrophysics Data System (ADS)

Riboldi, Stefano; Gerda Collaboration

2013-08-01

Phase I of GERDA, aimed at investigating neutrino-less double beta decay of 76Ge is in the active phase since November 2011 at the Gran Sasso National Laboratory of INFN-Italy. GERDA Ge detectors are non-encapsulated and operate immersed in liquid argon, equipped with a front-end readout electronics consisting of cryogenic charge sensitive preamplifiers designed and manufactured to cope with the characteristics of the GERDA experiment (radio-purity, long and resistive cables, etc.). The presentation will report on the current status of the GERDA experiment phase I, focusing on Ge detectors performance in terms of energy resolution, stability over time, counting rate and related issues.

Single-Shot Charge Readout Using a Cryogenic Heterojunction Bipolar Transistor Preamplifier Inline with a Silicon Single Electron Transistor at Millikelvin Temperatures

NASA Astrophysics Data System (ADS)

Curry, Matthew; England, Troy; Wendt, Joel; Pluym, Tammy; Lilly, Michael; Carr, Stephen; Carroll, Malcolm

Single-shot readout is a requirement for many implementations of quantum information processing. The single-shot readout fidelity is dependent on the signal-to-noise-ratio (SNR) and bandwidth of the readout detection technique. Several different approaches are being pursued to enhance read-out including RF-reflectometry, RF-transmission, parametric amplification, and transistor-based cryogenic preamplification. The transistor-based cryogenic preamplifier is attractive in part because of the reduced experimental complexity compared with the RF techniques. Here we present single-shot charge readout using a cryogenic Heterojunction-Bipolar-Transistor (HBT) inline with a silicon SET charge-sensor at millikelvin temperatures. For the relevant range of HBT DC-biasing, the current gain is 100 to 2000 and the power dissipation is 50 nW to 5 μW, with the microfabricated SET and discrete HBT in an integrated package mounted to the mixing chamber stage of a dilution refrigerator. We experimentally demonstrate a SNR of up to 10 with a bandwidth of 1 MHz, corresponding to a single-shot time-domain charge-sensitivity of approximately 10-4 e / √Hz. This measured charge-sensitivity is comparable to the values reported using the RF techniques. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the U. S. Department of Energy under Contract No. DE-AC04-94AL85000.

Frontend electronics for high-precision single photo-electron timing using FPGA-TDCs

NASA Astrophysics Data System (ADS)

Cardinali, M.; Dzyhgadlo, R.; Gerhardt, A.; Götzen, K.; Hohler, R.; Kalicy, G.; Kumawat, H.; Lehmann, D.; Lewandowski, B.; Patsyuk, M.; Peters, K.; Schepers, G.; Schmitt, L.; Schwarz, C.; Schwiening, J.; Traxler, M.; Ugur, C.; Zühlsdorf, M.; Dodokhov, V. Kh.; Britting, A.; Eyrich, W.; Lehmann, A.; Uhlig, F.; Düren, M.; Föhl, K.; Hayrapetyan, A.; Kröck, B.; Merle, O.; Rieke, J.; Cowie, E.; Keri, T.; Montgomery, R.; Rosner, G.; Achenbach, P.; Corell, O.; Ferretti Bondy, M. I.; Hoek, M.; Lauth, W.; Rosner, C.; Sfienti, C.; Thiel, M.; Bühler, P.; Gruber, L.; Marton, J.; Suzuki, K.

2014-12-01

The next generation of high-luminosity experiments requires excellent particle identification detectors which calls for Imaging Cherenkov counters with fast electronics to cope with the expected hit rates. A Barrel DIRC will be used in the central region of the Target Spectrometer of the planned PANDA experiment at FAIR. A single photo-electron timing resolution of better than 100 ps is required by the Barrel DIRC to disentangle the complicated patterns created on the image plane. R&D studies have been performed to provide a design based on the TRB3 readout using FPGA-TDCs with a precision better than 20 ps RMS and custom frontend electronics with high-bandwidth pre-amplifiers and fast discriminators. The discriminators also provide time-over-threshold information thus enabling walk corrections to improve the timing resolution. Two types of frontend electronics cards optimised for reading out 64-channel PHOTONIS Planacon MCP-PMTs were tested: one based on the NINO ASIC and the other, called PADIWA, on FPGA discriminators. Promising results were obtained in a full characterisation using a fast laser setup and in a test experiment at MAMI, Mainz, with a small scale DIRC prototype.

Cryogenic preamplification of a single-electron-transistor using a silicon-germanium heterojunction-bipolar-transistor

NASA Astrophysics Data System (ADS)

Curry, M. J.; England, T. D.; Bishop, N. C.; Ten-Eyck, G.; Wendt, J. R.; Pluym, T.; Lilly, M. P.; Carr, S. M.; Carroll, M. S.

2015-05-01

We examine a silicon-germanium heterojunction bipolar transistor (HBT) for cryogenic pre-amplification of a single electron transistor (SET). The SET current modulates the base current of the HBT directly. The HBT-SET circuit is immersed in liquid helium, and its frequency response from low frequency to several MHz is measured. The current gain and the noise spectrum with the HBT result in a signal-to-noise-ratio (SNR) that is a factor of 10-100 larger than without the HBT at lower frequencies. The transition frequency defined by SNR = 1 has been extended by as much as a factor of 10 compared to without the HBT amplification. The power dissipated by the HBT cryogenic pre-amplifier is approximately 5 nW to 5 μW for the investigated range of operation. The circuit is also operated in a single electron charge read-out configuration in the time-domain as a proof-of-principle demonstration of the amplification approach for single spin read-out.

Sensor Amplifier for the Venus Ground Ambient

NASA Technical Reports Server (NTRS)

DelCastillo, Linda Y.; Johnson, Travis W.; Hatake, Toshiro; Mojarradi, Mohammad M.; Kolawa, Elizabeth A.

2006-01-01

Previous Venus Landers employed high temperature pressure vessels, with thermally protected electronics, to achieve successful missions, with a maximum surface lifetime of 127 minutes. Extending the operating range of electronic systems to the temperatures (480 C) and pressures (90 bar) of the Venus ground ambient would significantly increase the science return of future missions. Toward that end, the current work describes the innovative design of a sensor preamplifier, capable of working in the Venus ground ambient and designed using commercial components (thermionic vacuum tubes, wide band gap transistors, thick film resistors, advanced high temperature capacitors, and monometallic interfaces) To identify commercial components and electronic packaging materials that are capable of operation within the specified environment, a series of active devices, passive components, and packaging materials were screened for operability at 500C, assuming a 10x increase in the mission lifetime. In addition. component degradation as a function of time at 500(deg)C was evaluated. Based on the results of these preliminary evaluations, two amplifiers were developed.

Detection of pulsed bremsstrahlung-induced prompt neutron capture gamma rays with a HPGe detector

NASA Astrophysics Data System (ADS)

Jones, James L.

1997-02-01

The Idaho National Engineering Laboratory (INEL) is developing a novel photoneutron-based nondestructive evaluation technique which uses a pulsed, high-energy electron accelerator and gamma-ray spectrometry. Highly penetrating pulses of bremsstrahlung photons are produced by each pulse of electrons. Interrogating neutrons are generated by the bremsstrahlung photons interacting within a photoneutron source material. The interactions of the neutrons within a target result in the emission of elemental characteristic gamma-rays. Spectrometry is performed by analyzing the photoneutron-induced, prompt gama-rays acquired between accelerator pulses with a unique, high- purity germanium gamma-ray detection system using a modified transistor reset preamplifier. The detection system, the experimental configuration, and the accelerator operation used to characterize the detection systems performance are described. Using a 6.5-MeV electron accelerator and a beryllium metal photoneutron source, gamma-ray spectra were successfully acquired for Al, Cu, polyethylene, NaCl, and depleted uranium targets as soon as 30 microsecond(s) after each bremsstrahlung flash.

Pulse-height loss in the signal readout circuit of compound semiconductor detectors

NASA Astrophysics Data System (ADS)

Nakhostin, M.; Hitomi, K.

2018-06-01

Compound semiconductor detectors such as CdTe, CdZnTe, HgI2 and TlBr are known to exhibit large variations in their charge collection times. This paper considers the effect of such variations on the measurement of induced charge pulses by using resistive feedback charge-sensitive preamplifiers. It is shown that, due to the finite decay-time constant of the preamplifiers, the capacitive decay during the signal readout leads to a variable deficit in the measurement of ballistic signals and a digital pulse processing method is employed to correct for it. The method is experimentally examined by using sampled pulses from a TlBr detector coupled to a charge-sensitive preamplifier with 150 μs of decay-time constant and 20 % improvement in the energy resolution of the detector at 662 keV is achieved. The implications of the capacitive decay on the correction of charge-trapping effect by using depth-sensing technique are also considered.

Inexpensive read-out for coincident electron spectroscopy with a transmission electron microscope at nanometer scale using micro channel plates and multistrip anodes

NASA Astrophysics Data System (ADS)

Hollander, R. W.; Bom, V. R.; van Eijk, C. W. E.; Faber, J. S.; Hoevers, H.; Kruit, P.

1994-09-01

The elemental composition of a sample at nanometer scale is determined by measurement of the characteristic energy of Auger electrons, emitted in coincidence with incoming primary electrons from a microbeam in a scanning transmission electron microscope (STEM). Single electrons are detected with position sensitive detectors, consisting of MicroChannel Plates (MCP) and MultiStrip Anodes (MSA), one for the energy of the Auger electrons (Auger-detector) and one for the energy loss of primary electrons (EELS-detector). The MSAs are sensed with LeCroy 2735DC preamplifiers. The fast readout is based on LeCroy's PCOS III system. On the detection of a coincidence (Event) energy data of Auger and EELS are combined with timing data to an Event word. Event words are stored in list mode in a VME memory module. Blocks of Event words are scanned by transputers in VME and two-dimensional energy histograms are filled using the timing information to obtain a maximal true/accidental ratio. The resulting histograms are stored on disk of a PC-386, which also controls data taking. The system is designed to handle 10 5 Events per second, 90% of which are accidental. In the histograms the "true" to "accidental" ratio will be 5. The dead time is 15%.

The Noise Level Optimization for Induction Magnetometer of SEP System

NASA Astrophysics Data System (ADS)

Zhu, W.; Fang, G.

2011-12-01

The Surface Electromagnetic Penetration (SEP) System, subsidized by the SinoProbe Plan in China, is designed for 3D conductivity imaging in geophysical mineral exploration, underground water distribution exploration, oil and gas reservoir exploration. Both the Controlled Source Audio Magnetotellurics (CSAMT) method and Magnetotellurics (MT) method can be surveyed by SEP system. In this article, an optimization design is introduced, which can minimize the noise level of the induction magnetometer for SEP system magnetic field's acquisition. The induction magnetometer transfers the rate of the magnetic field's change to voltage signal by induction coil, and amplified it by Low Noise Amplifier The noise parts contributed to the magnetometer are: the coil's thermal noise, the equivalent input voltage and current noise of the pre-amplifier. The coil's thermal noise is decided by coil's DC resistance. The equivalent input voltage and current noise of the pre-amplifier depend on the amplifier's type and DC operation condition. The design here optimized the DC operation point of pre-amplifier, adjusted the DC current source, and realized the minimum of total noise level of magnetometer. The calculation and test results show that: the total noise is about 1pT/√Hz, the thermal noise of coils is 1.7nV/√Hz, the preamplifier equivalent input voltage and current noise is 3nV/ √Hz and 0.1pA/√Hz, the weight of the magnetometer is 4.5kg and meet the requirement of SEP system.

Validating Mobile Electroencephalographic Systems for Integration into the PhyCORE and Application in Clinical Settings

DTIC Science & Technology

2016-09-26

placement. The preamplifier mounted on top of the headset samples EEG signals at 300 Hz; it then transmits the raw EEG data via Bluetooth ® to a data...The preamplifier mounted on the back of the headset samples EEG signals at 256 Hz and then transmits the raw EEG data via Bluetooth ® to a data...electrooculography. The batteries will last 6 hours using Bluetooth ® or 16 hours if data are recorded directly onto a secure digital card. A three-axis

The design of preamplifier and ADC circuit base on weak e-optical signal

NASA Astrophysics Data System (ADS)

Fen, Leng; Ying-ping, Yang; Ya-nan, Yu; Xiao-ying, Xu

2011-02-01

Combined with the demand of the process of weak e-optical signal in QPD detection system, the article introduced the circuit principle of deigning preamplifier and ADC circuit with I/V conversion, instrumentation amplifier, low-pass filter and 16-bit A/D transformation. At the same time the article discussed the circuit's noise suppression and isolation according to the characteristics of the weak signal, and gave the method of software rectification. Finally, tested the weak signal with keithley2000, and got a good effect.

Performance studies of X3 silicon detectors for the future ELISSA array at ELI-NP

NASA Astrophysics Data System (ADS)

Chesnevskaya, S.; Balabanski, D. L.; Choudhury, D.; Constantin, P.; Filipescu, D. M.; Ghita, D. G.; Guardo, G. L.; Lattuada, D.; Matei, C.; Rotaru, A.; State, A.

2018-05-01

ELISSA is an array of silicon strip detectors under construction at the ELI-NP facility for measurements of photodissociation reactions using high-brilliance, quasi monoenergetic gamma beams. The detection system consists of 35 single-sided position-sensitive X3 detectors arranged in a cylindrical configuration and eight QQQ3 detectors as end-caps. A batch of forty X3 detectors have been tested at ELI-NP. The energy and position resolution, ballistic deficit, leakage currents, and depletion voltage were measured and analyzed. Measurements of the energy resolution were carried out using two read-out electronic chains, one based on multichannel preamplifiers and another based on multiplexers.

Optically pre-amplified lidar-radar

NASA Astrophysics Data System (ADS)

Morvan, Loic; Dolfi, Daniel; Huignard, Jean-Pierre

2001-09-01

We present the concept of an optically pre-amplified intensity modulated lidar, where the modulation frequency is in the microwave domain (1-10 GHz). Such a system permits to combine directivity of laser beams with mature radar processing. As an intensity modulated or dual-frequency laser beam is directed on a target, the backscattered intensity is collected by an optical system, pass through an optical preamplifier, and is detected on a high speed photodiode in a direct detection scheme. A radar type processing permits then to extract range, speed and identification information. The association of spatially multimode amplifier and direct detection allows low sensitivity to atmospheric turbulence and large field of view. We demonstrated theoretically that optical pre-amplification can greatly enhance sensitivity, even in spatially multimode amplifiers, such as free-space amplifier or multimode doped fiber. Computed range estimates based on this concept are presented. Laboratory demonstrations using 1 to 3 GHz modulated laser sources and >20 dB gain in multimode amplifiers are detailed. Preliminary experimental results on range and speed measurements and possible use for large amplitude vibrometry will be presented.

[Experimental investigation of laser plasma soft X-ray source with gas target].

PubMed

Ni, Qi-liang; Gong, Yan; Lin, Jing-quan; Chen, Bo; Cao, Jian-lin

2003-02-01

This paper describes a debris-free laser plasma soft X-ray source with a gas target, which has high operating frequency and can produce strong soft X-ray radiation. The valve of this light source is drived by a piezoelectrical ceramic whose operating frequency is up to 400 Hz. In comparison with laser plasma soft X-ray sources using metal target, the light source is debris-free. And it has higher operating frequency than gas target soft X-ray sources whose nozzle is controlled by a solenoid valve. A channel electron multiplier (CEM) operating in analog mode is used to detect the soft X-ray generated by the laser plasma source, and the CEM's output is fed to to a charge-sensitive preamplifier for further amplification purpose. Output charges from the CEM are proportional to the amplitude of the preamplifier's output voltage. Spectra of CO2, Xe and Kr at 8-14 nm wavelength which can be used for soft X-ray projection lithography are measured. The spectrum for CO2 consists of separate spectral lines originate mainly from the transitions in Li-like and Be-like ions. The Xe spectrum originating mainly from 4d-5f, 4d-4f, 4d-6p and 4d-5p transitions in multiply charged xenon ions. The spectrum for Kr consists of separate spectral lines and continuous broad spectra originating mainly from the transitions in Cu-, Ni-, Co- and Fe-like ions.

SNR Improvement of QEPAS System by Preamplifier Circuit Optimization and Frequency Locked Technique

NASA Astrophysics Data System (ADS)

Zhang, Qinduan; Chang, Jun; Wang, Zongliang; Wang, Fupeng; Jiang, Fengting; Wang, Mengyao

2018-06-01

Preamplifier circuit noise is of great importance in quartz enhanced photoacoustic spectroscopy (QEPAS) system. In this paper, several noise sources are evaluated and discussed in detail. Based on the noise characteristics, the corresponding noise reduction method is proposed. In addition, a frequency locked technique is introduced to further optimize the QEPAS system noise and improve signal, which achieves a better performance than the conventional frequency scan method. As a result, the signal-to-noise ratio (SNR) could be increased 14 times by utilizing frequency locked technique and numerical averaging technique in the QEPAS system for water vapor detection.

Circuit Methods for VLF Antenna Couplers. [for use in Loran or Omega receiver systems

NASA Technical Reports Server (NTRS)

Burhans, R. W.

1977-01-01

The limitations of different E-field antenna coupler or preamplifier circuits are presented. All circuits were evaluated using actual Loran or Omega signals. Electric field whip or wire antennas are the simplest types which can be used for reception of VLF signals in the 10 to 100 kHz range. JFET or MOSFET transistors provide impedance transformation and some voltage gain in simple circuits where the power for operating the preamplifier uses the same coaxial cable that feeds the signal back to the receiver. The circuit techniques provide useful alternative methods for Loran-Omega receiver system designers.

Cryogenic preamplification of a single-electron-transistor using a silicon-germanium heterojunction-bipolar-transistor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Curry, M. J.; Center for Quantum Information and Control, University of New Mexico, Albuquerque, New Mexico 87131; Sandia National Laboratories, 1515 Eubank Blvd SE, Albuquerque, New Mexico 87123

2015-05-18

We examine a silicon-germanium heterojunction bipolar transistor (HBT) for cryogenic pre-amplification of a single electron transistor (SET). The SET current modulates the base current of the HBT directly. The HBT-SET circuit is immersed in liquid helium, and its frequency response from low frequency to several MHz is measured. The current gain and the noise spectrum with the HBT result in a signal-to-noise-ratio (SNR) that is a factor of 10–100 larger than without the HBT at lower frequencies. The transition frequency defined by SNR = 1 has been extended by as much as a factor of 10 compared to without the HBT amplification.more » The power dissipated by the HBT cryogenic pre-amplifier is approximately 5 nW to 5 μW for the investigated range of operation. The circuit is also operated in a single electron charge read-out configuration in the time-domain as a proof-of-principle demonstration of the amplification approach for single spin read-out.« less

The electronics, trigger and data acquisition system for the liquid argon time projection chamber of the DarkSide-50 search for dark matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agnes, P.; Albuquerque, I. F. M.; Alexander, T.

The DarkSide-50 experiment at the Laboratori Nazionali del Gran Sasso is a search for dark matter using a dual phase time projection chamber with 50 kg of low radioactivity argon as target. Light signals from interactions in the argon are detected by a system of 38 photo-multiplier tubes (PMTs), 19 above and 19 below the TPC volume inside the argon cryostat. We describe the electronics which processes the signals from the photo-multipliers, the trigger system which identifies events of interest, and the data-acquisition system which records the data for further analysis. The electronics include resistive voltage dividers on the PMTs,more » custom pre-amplifiers mounted directly on the PMT voltage dividers in the liquid argon, and custom amplifier/discriminators (at room temperature). After amplification, the PMT signals are digitized in CAEN waveform digitizers, and CAEN logic modules are used to construct the trigger, the data acquisition system for the TPC is based on the Fermilab "artdaq" software. The system has been in operation since early 2014.« less

The electronics, trigger and data acquisition system for the liquid argon time projection chamber of the DarkSide-50 search for dark matter

NASA Astrophysics Data System (ADS)

Agnes, P.; Albuquerque, I. F. M.; Alexander, T.; Alton, A. K.; Arisaka, K.; Asner, D. M.; Ave, M.; Back, H. O.; Baldin, B.; Biery, K.; Bocci, V.; Bonfini, G.; Bonivento, W.; Bossa, M.; Bottino, B.; Brigatti, A.; Brodsky, J.; Budano, F.; Bussino, S.; Cadeddu, M.; Cadoni, M.; Calaprice, F.; Canci, N.; Candela, A.; Cao, H.; Caravati, M.; Cariello, M.; Carlini, M.; Catalanotti, S.; Cataudella, V.; Cavalcante, P.; Chepurnov, A.; Cicaló, C.; Cocco, A. G.; Covone, G.; Crippa, L.; D'Angelo, D.; D'Incecco, M.; Davini, S.; de Candia, A.; De Cecco, S.; De Deo, M.; De Filippis, G.; De Rosa, G.; De Vincenzi, M.; Derbin, A.; Devoto, A.; Di Eusanio, F.; Dionisi, C.; Di Pietro, G.; Edkins, E.; Empl, A.; Fan, A.; Fiorillo, G.; Fomenko, K.; Forster, G.; Franco, D.; Gabriele, F.; Galbiati, C.; Giagu, S.; Giganti, C.; Giovanetti, G. K.; Goretti, A. M.; Granato, F.; Grandi, L.; Gromov, M.; Guan, M.; Guardincerri, Y.; Hackett, B. R.; Herner, K. R.; Hughes, D.; Humble, P.; Hungerford, E. V.; Ianni, A.; Ianni, A.; James, I.; Johnson, T. N.; Keeter, K.; Kendziora, C. L.; Kobychev, V.; Koh, G.; Korablev, D.; Korga, G.; Kubankin, A.; Li, X.; Lissia, M.; Loer, B.; Lombardi, P.; Longo, G.; Luitz, S.; Ma, Y.; Machado, A.; Machulin, I. N.; Mandarano, A.; Mari, S. M.; Maricic, J.; Marini, L.; Martoff, C. J.; Meyers, P. D.; Miletic, T.; Milincic, R.; Montanari, D.; Monte, A.; Montuschi, M.; Monzani, M. E.; Mosteiro, P.; Mount, B. J.; Muratova, V. N.; Musico, P.; Navrer Agasson, A.; Nelson, A.; Odrowski, S.; Oleinik, A.; Orsini, M.; Ortica, F.; Pagani, L.; Pallavicini, M.; Pantic, E.; Parmeggiano, S.; Pelczar, K.; Pelliccia, N.; Pocar, A.; Pordes, S.; Pugachev, D. A.; Qian, H.; Randle, K.; Ranucci, G.; Razeti, M.; Razeto, A.; Reinhold, B.; Renshaw, A. L.; Rescigno, M.; Riffard, Q.; Romani, A.; Rossi, B.; Rossi, N.; Rountree, S. D.; Sablone, D.; Saggese, P.; Saldanha, R.; Sands, W.; Sangiorgio, S.; Savarese, C.; Schlitzer, B.; Segreto, E.; Semenov, D. A.; Shields, E.; Singh, P. N.; Skorokhvatov, M. D.; Smirnov, O.; Sotnikov, A.; Stanford, C.; Suvorov, Y.; Tartaglia, R.; Tatarowicz, J.; Testera, G.; Tonazzo, A.; Trinchese, P.; Unzhakov, E. V.; Verducci, M.; Vishneva, A.; Vogelaar, R. B.; Wada, M.; Walker, S.; Wang, H.; Wang, Y.; Watson, A. W.; Westerdale, S.; Wojcik, M. M.; Xiang, X.; Xiao, X.; Xu, J.; Yang, C.; Yoo, J.; Zavatarelli, S.; Zec, A.; Zhong, W.; Zhu, C.; Zuzel, G.

2017-12-01

The DarkSide-50 experiment at the Laboratori Nazionali del Gran Sasso is a search for dark matter using a dual phase time projection chamber with 50 kg of low radioactivity argon as target. Light signals from interactions in the argon are detected by a system of 38 photo-multiplier tubes (PMTs), 19 above and 19 below the TPC volume inside the argon cryostat. We describe the electronics which processes the signals from the photo-multipliers, the trigger system which identifies events of interest, and the data-acquisition system which records the data for further analysis. The electronics include resistive voltage dividers on the PMTs, custom pre-amplifiers mounted directly on the PMT voltage dividers in the liquid argon, and custom amplifier/discriminators (at room temperature). After amplification, the PMT signals are digitized in CAEN waveform digitizers, and CAEN logic modules are used to construct the trigger; the data acquisition system for the TPC is based on the Fermilab artdaq software. The system has been in operation since early 2014.

Ultra-Low Noise Germanium Neutrino Detection system (ULGeN).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cabrera-Palmer, Belkis; Barton, Paul

Monitoring nuclear power plant operation by measuring the antineutrino flux has become an active research field for safeguards and non-proliferation. We describe various efforts to demonstrate the feasibility of reactor monitoring based on the detection of the Coherent Neutrino Nucleus Scattering (CNNS) process with High Purity Germanium (HPGe) technology. CNNS detection for reactor antineutrino energies requires lowering the electronic noise in low-capacitance kg-scale HPGe detectors below 100 eV as well as stringent reduction in other particle backgrounds. Existing state- of-the-art detectors are limited to an electronic noise of 95 eV-FWHM. In this work, we employed an ultra-low capacitance point-contact detectormore » with a commercial integrated circuit preamplifier- on-a-chip in an ultra-low vibration mechanically cooled cryostat to achieve an electronic noise of 39 eV-FWHM at 43 K. We also present the results of a background measurement campaign at the Spallation Neutron Source to select the area with sufficient low background to allow a successful first-time measurement of the CNNS process.« less

Cryogenic Preamplification of a Single-Electron-Transistor using a Silicon-Germanium Heterojunction-Bipolar-Transistor

DOE PAGES

Curry, Matthew J.; England, Troy Daniel; Bishop, Nathaniel; ...

2015-05-21

We examine a silicon-germanium heterojunction bipolar transistor (HBT) for cryogenic pre-amplification of a single electron transistor (SET). The SET current modulates the base current of the HBT directly. The HBT-SET circuit is immersed in liquid helium, and its frequency response from low frequency to several MHz is measured. The current gain and the noise spectrum with the HBT result in a signal-to-noise-ratio (SNR) that is a factor of 10–100 larger than without the HBT at lower frequencies. Furthermore, the transition frequency defined by SNR = 1 has been extended by as much as a factor of 10 compared to withoutmore » the HBT amplification. The power dissipated by the HBT cryogenic pre-amplifier is approximately 5 nW to 5 μW for the investigated range of operation. We found that the circuit is also operated in a single electron charge read-out configuration in the time-domain as a proof-of-principle demonstration of the amplification approach for single spin read-out.« less

The electronics, trigger and data acquisition system for the liquid argon time projection chamber of the DarkSide-50 search for dark matter

DOE PAGES

Agnes, P.; Albuquerque, I. F. M.; Alexander, T.; ...

2017-12-01

The DarkSide-50 experiment at the Laboratori Nazionali del Gran Sasso is a search for dark matter using a dual phase time projection chamber with 50 kg of low radioactivity argon as target. Light signals from interactions in the argon are detected by a system of 38 photo-multiplier tubes (PMTs), 19 above and 19 below the TPC volume inside the argon cryostat. We describe the electronics which processes the signals from the photo-multipliers, the trigger system which identifies events of interest, and the data-acquisition system which records the data for further analysis. The electronics include resistive voltage dividers on the PMTs,more » custom pre-amplifiers mounted directly on the PMT voltage dividers in the liquid argon, and custom amplifier/discriminators (at room temperature). After amplification, the PMT signals are digitized in CAEN waveform digitizers, and CAEN logic modules are used to construct the trigger, the data acquisition system for the TPC is based on the Fermilab "artdaq" software. The system has been in operation since early 2014.« less

Symmetric 40-Gb/s TWDM-PON with 51-dB loss budget by using a single SOA as preamplifier, booster and format converter in ONU.

PubMed

Li, Zhengxuan; Yi, Lilin; Hu, Weisheng

2014-10-06

In this paper, we propose to use a semiconductor optical amplifier (SOA) in the optical network unit (ONU) to improve the loss budget in time and wavelength division multiplexed-passive optical network (TWDM-PON) systems. The SOA boosts the upstream signal to increase the output power of the electro-absorption modulated laser (EML) and simultaneously pre-amplifies the downstream signal for sensitivity improvement. The penalty caused by cross gain modulation (XGM) effect is negligible due to the low extinction ratio (ER) of upstream signal and the large wavelength difference between upstream and downstream links. In order to achieve a higher output power, the SOA is driven into its saturation region, where the self-phase modulation (SPM) effect converts the intensity into phase information and realizes on-off-keying (OOK) to phase-shifted-keying (PSK) format conversion. In this way, the pattern effect is eliminated, which releases the requirement of gain-clamping on SOA. To further improve the loss budget of upstream link, an Erbium doped fiber amplifier (EDFA) is used in the optical line terminal (OLT) to pre-amplify the received signal. For the downstream direction, directly modulated laser (DML) is used as the laser source. Taking advantage of its carrier-less characteristic, directly modulated signal shows high tolerance to fiber nonlinearity, which could support a downstream launch power as high as + 16 dBm per channel. In addition, the signal is pre-amplified by the SOA in ONU before being detected, so the sensitivity limitation for downstream link is also removed. As a result, a truly passive symmetric 40-Gb/s TWDM-PON was demonstrated, achieving a link loss budget of 51 dB.

LWS design replacement study: Optimum design and tradeoff analysis

NASA Technical Reports Server (NTRS)

1973-01-01

A design for two long-wavelength (LW) focal-plane and cooler assemblies, including associated preamplifiers and post-amplifiers is presented. The focal-planes and associated electronic assemblies are intended as direct replacement hardware to be installed into the existing 24-channel multispectral scanner used with the NASA Earth Observations Aircraft Program. An organization skilled in the art of LWIR systems can fabricate and deliver the two long-wavelength focal-plane assemblies described in this report when provided with the data and drawings developed during the performance of this contract. The concepts developed during the study including the alternative approaches and selection of components are discussed. Modifications to the preliminary design as reported in a preliminary design review meeting have also been included.

A modular solid state detector for measuring high energy heavy ion fragmentation near the beam axis

NASA Technical Reports Server (NTRS)

Zeitlin, C. J.; Frankel, K. A.; Gong, W.; Heilbronn, L.; Lampo, E. J.; Leres, R.; Miller, J.; Schimmerling, W.

1994-01-01

A multi-element solid state detector has been designed to measure fluences of fragments produced near the beam axis by high energy heavy ion beams in thick targets. The detector is compact and modular, so as to be readily reconfigured according to the range of fragment charges and energies to be measured. Preamplifier gain settings and detector calibrations are adjustable remotely under computer control. We describe the central detector, its associated detectors and electronics, triggering scheme, data acquisition and particle identification techniques, illustrated by data taken with 600 MeV/u 56Fe beams and thick polyethylene targets at the LBL Bevalac. The applications of this work to space radiation protection are discussed.

Combined PET/MRI scanner

DOEpatents

Schlyer, David; Woody, Craig L.; Rooney, William; Vaska, Paul; Stoll, Sean; Pratte, Jean-Francois; O'Connor, Paul

2007-10-23

A combined PET/MRI scanner generally includes a magnet for producing a magnetic field suitable for magnetic resonance imaging, a radiofrequency (RF) coil disposed within the magnetic field produced by the magnet and a ring tomograph disposed within the magnetic field produced by the magnet. The ring tomograph includes a scintillator layer for outputting at least one photon in response to an annihilation event, a detection array coupled to the scintillator layer for detecting the at least one photon outputted by the scintillator layer and for outputting a detection signal in response to the detected photon and a front-end electronic array coupled to the detection array for receiving the detection signal, wherein the front-end array has a preamplifier and a shaper network for conditioning the detection signal.

A study of timing properties of Silicon Photomultipliers

NASA Astrophysics Data System (ADS)

Avella, Paola; De Santo, Antonella; Lohstroh, Annika; Sajjad, Muhammad T.; Sellin, Paul J.

2012-12-01

Silicon Photomultipliers (SiPMs) are solid-state pixelated photodetectors. Lately these sensors have been investigated for Time of Flight Positron Emission Tomography (ToF-PET) applications, where very good coincidence time resolution of the order of hundreds of picoseconds imply spatial resolution of the order of cm in the image reconstruction. The very fast rise time typical of the avalanche discharge improves the time resolution, but can be limited by the readout electronics and the technology used to construct the device. In this work the parameters of the equivalent circuit of the device that directly affect the pulse shape, namely the quenching resistance and capacitance and the diode and parasitic capacitances, were calculated. The mean rise time obtained with different preamplifiers was also measured.

GaAs Spectrometer for Electron Spectroscopy at Europa

NASA Astrophysics Data System (ADS)

Lioliou, G.; Barnett, A. M.

2016-12-01

We propose a GaAs based electron spectrometer for a hypothetical future mission orbiting Europa. Previous observations at Europa's South Pole with the Hubble Space Telescope of hydrogen Lyman-α and oxygen OI 130.4 nm emissions were consistent with water vapor plumes [Roth et al., 2014, Science 343, 171]. Future observations and analysis of plumes on Europa could provide information about its subsurface structure and the distribution of liquid water within its icy shells [Rhoden at al. 2015, Icarus 253, 169]. In situ low energy (1keV - 100keV) electron spectroscopy along with UV imaging either in situ or with the Hubble Space Telescope Wide Field Camera 3 or similar would allow verification of the auroral observations being due to electron impact excitation of water vapor plumes. The proposed spectrometer includes a novel GaAs p+-i-n+ photodiode and a custom-made charge-sensitive preamplifier. The use of an early prototype GaAs detector for direct electron spectroscopy has already been demonstrated in ground based applications [Barnett et al., 2012, J. Instrum. 7, P09012]. Based on previous radiation hardness measurements of GaAs, the expected duration of the mission without degradation of the detector performance is estimated to be 4 months. Simulations and laboratory experiments characterising the detection performance of the proposed system are presented.

An Alpha Proton X-Ray Spectrometer for Mars-96 and Mars Pathfinder

NASA Astrophysics Data System (ADS)

Rieder, R.; Wanke, H.; Economou, T.

1996-09-01

Mars Pathfinder and the Russian Mars-96 will carry an Alpha Proton X-Ray Spectrometer (APXS) for the determination of the chemical composition of Martian rocks and soil. The instrument will measure the concentration of all major and many minor elements, including C,N and O, at levels above typically 1%. The method employed consist of bombarding a sample of 50 mm diameter with alpha particles from a radioactive source (50 mCi of Cm-244) and measuring: (i) backscattered alpha particles (alpha mode) (ii) protons from (a,p) reactions with some light elements (proton mode) (iii) characteristic X-rays emitted from the sample (X-ray mode). The APXS has a long standing space heritage, going back to Surveyor V,VI and VII (1967/68) and the Soviet Phobos (1988) missions. The present design is the result of an endeavour to reduce mass and power consumption to 600g/ 300mW. It consist of a sensor head containing the alpha sources, a telescope of a silicon detectors for the detection of the alpha particles and protons and a separate X-ray detector with its preamplifier, and an electronics box (80x70x60 mm) containing a microcontroller based multichannel spectrometer. The paper will describe the APXS flight hardware and present results obtained with the flight instrument that will show the instrument capabili- ties and the expected results to be obtained during surface operations on Mars.

Prototype of IGZO-TFT preamplifier and analog counter for pixel detector

NASA Astrophysics Data System (ADS)

Shimazoe, K.; Koyama, A.; Takahashi, H.; Shindoh, T.; Miyoshi, H.

2017-02-01

IGZO-TFT (Indium Galium Zinc Oxide-Thin Film Transistor) is a promising technology for controlling large display areas and large area sensors because of its very low leakage current in the off state and relatively low cost. IGZO has been used as a switching gate for a large area flat-panel detector. The photon counting capability for X-ray medical imaging has been investigated and expected for low-dose exposure and material determination. Here the design and fabrication of a charge sensitive preamplifier and analog counter using IGZO-TFT processes and its performance are reported for the first time to be used for radiation photon counting applications.

Dedicated power supply subsystem for ultra-low noise preamplifiers and biophotonic sensors

NASA Astrophysics Data System (ADS)

SuraŻyński, Łukasz; Wierzba, Paweł; Zienkiewicz, Aleksandra

2013-11-01

It is very common for noise to have an influence on analog circuits. In order to preserve the quality of measurements taken by specific sensors and any noise dependent amplifiers which are correlated to them, all of these devices must be powered by low-noise power supplies. Therefore a necessity exists to develop new ultra-low noise power supplies which can cooperate with specified amplifiers and preamplifiers. Many well-known power supplies are particularly expensive and yet still have their disadvantages. This paper proposes a simple and inexpensive solution, which fulfills a specific criteria and can be treated as a base for improvement.

Construction and test of a fine-grained liquid argon preshower prototype

NASA Astrophysics Data System (ADS)

Davis, R. A.; Gingrich, D. M.; Pinfold, J. L.; Rodning, N. L.; Boos, E.; Zhautykov, B. O.; Aubert, B.; Bazan, A.; Beaugiraud, B.; Boniface, J.; Colas, J.; Eynard, G.; Jezequel, S.; Leflour, T.; Linossier, O.; Nicoleau, S.; Rival, F.; Sauvage, G.; Thion, J.; VanDenPlas, D.; Wingerter-Seez, I.; Zitoun, R.; Zolnierowski, Y. P.; Chmeissani, M.; Fernandez, E.; Garrido, Ll.; Martinez, M.; Padilla, C.; Gordon, H. A.; Radeka, V.; Rahm, D.; Stephani, D.; Baisin, L.; Berset, J. C.; Chevalley, J. L.; Gianotti, F.; Gildemeister, O.; Marin, C. P.; Nessi, M.; Poggioli, L.; Richter, W.; Vuillemin, V.; Baze, J. M.; Gosset, L.; Lavocat, P.; Lottin, J. P.; Mansoulié, B.; Meyer, J. P.; Renardy, J. F.; Schwindling, J.; Teiger, J.; Collot, J.; de Saintignon, P.; Dzahini, D.; Hostachy, J. Y.; Hoummada, A.; Laborie, G.; Mahout, G.; Hervas, L.; Chekhtman, A.; Cousinou, M. C.; Dargent, P.; Dinkespiller, B.; Etienne, F.; Fassnacht, P.; Fouchez, D.; Martin, L.; Miotto, A.; Monnier, E.; Nagy, E.; Olivetto, C.; Tisserant, S.; Battistoni, G.; Camin, D. V.; Cavalli, D.; Costa, G.; Cozzi, L.; Fedyakin, N.; Ferrari, A.; Mandelli, L.; Mazzanti, M.; Perini, L.; Resconi, S.; Sala, P.; Beaudoin, G.; Depommier, P.; León-Florián, E.; Leroy, C.; Roy, P.; Augé, E.; Chase, R.; Chollet, J. C.; de La Taille, C.; Fayard, L.; Fournier, D.; Hrisoho, A.; Merkel, B.; Noppe, J. M.; Parrour, G.; Pétroff, P.; Schaffer, A.; Seguin-Moreau, N.; Serin, L.; Tisserand, V.; Vichou, I.; Canton, B.; David, J.; Genat, J. F.; Imbault, D.; Le Dortz, O.; Savoy-Navarro, A.; Schwemling, P.; Eek, L. O.; Lund-Jensen, B.; Söderqvist, J.; Lefebvre, M.; Robertson, S.; RD3 Collaboration

1997-02-01

A separate liquid argon preshower detector consisting of two layers featuring a fine granularity of 2.5 × 10 -3 was studied by the RD3 collaboration. A prototype covering approximately 0.8 in pseudo-rapidity and 9° in azimuth was built and tested at CERN in July 94. CMOS and GaAs VLSI preamplifiers were designed and tested for this occasion. The combined response of this detector and an accordion electromagnetic calorimeter prototype to muons, electrons and photons is presented. For minimum ionizing tracks a signal-to-noise ratio of 4.5 per preshower layer was measured. Above 150 GeV the space resolution for electrons is better than 250 μm in both directions. The precision on the electromagnetic shower direction, determined together with the calorimeter, is better than 4 mrad above 50 GeV. It is concluded that the preshower detector would adequately fulfil its role for future operation at CERN Large Hadron Collider.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agnes, P.; Albuquerque, I. F. M.; Alexander, T.

The DarkSide-50 experiment at the Laboratori Nazionali del Gran Sasso is a search for dark matter using a dual phase time projection chamber with 50 kg of low radioactivity argon as target. Light signals from interactions in the argon are detected by a system of 38 photo-multiplier tubes (PMTs), 19 above and 19 below the TPC volume inside the argon cryostat. We describe the electronics which processes the signals from the photo-multipliers, the trigger system which identifies events of interest, and the data-acquisition system which records the data for further analysis. The electronics include resistive voltage dividers on the PMTs,more » custom pre-amplifiers mounted directly on the PMT voltage dividers in the liquid argon, and custom amplifier/discriminators (at room temperature). After amplification, the PMT signals are digitized in CAEN waveform digitizers, and CAEN logic modules are used to construct the trigger, the data acquisition system for the TPC is based on the Fermilab "artdaq" software. The system has been in operation since early 2014.« less

Solid state Ku-band spacecraft transmitters

NASA Technical Reports Server (NTRS)

Wisseman, W. R.; Tserng, H. Q.; Coleman, D. J.; Doerbeck, F. H.

1977-01-01

A transmitter is considered that consists of GaAs IMPATT and Read diodes operating in a microstrip circuit environment to provide amplification with a minimum of 63 db small signal gain and a minimum compressed gain at 5 W output of 57 db. Reported are Schottky-Read diode design and fabrication, microstrip and circulator optimization, preamplifier development, power amplifier development, dc-to-dc converter design, and integration of the breadboard transmitter modules. A four-stage power amplifier in cascade with a three-stage preamplifier had an overall gain of 56.5 db at 13.5 GHz with a power output of 4.5 W. A single-stage Read amplifier delivered 5.9 W with 4 db gain at 22% efficiency.

Integrating IR detector imaging systems

NASA Technical Reports Server (NTRS)

Bailey, G. C. (Inventor)

1984-01-01

An integrating IR detector array for imaging is provided in a hybrid circuit with InSb mesa diodes in a linear array, a single J-FET preamplifier for readout, and a silicon integrated circuit multiplexer. Thin film conductors in a fan out pattern deposited on an Al2O3 substrate connect the diodes to the multiplexer, and thick film conductors also connect the reset switch and preamplifier to the multiplexer. Two phase clock pulses are applied with a logic return signal to the multiplexer through triax comprised of three thin film conductors deposited between layers. A lens focuses a scanned image onto the diode array for horizontal read out while a scanning mirror provides vertical scan.

1.31-1.55-µm Hybrid integrated optoelectronic receiver using low-loss quasi-monolithic integration technology

NASA Astrophysics Data System (ADS)

Luo, Yang; Huang, Yongqing; Ren, Xiaomin; Duan, Xiaofeng; Wang, Qi

2014-01-01

In order to integrate photonic devices with electronic devices to realize the low-loss hybrid integrated devices. A wide spectral hybrid integrated optoelectronic receiver was fabricated by using quasi-monolithic integration technology (QMIT) in this paper. It consisted of a 8.5 GHz InGaAs photodetector and a 1.25 Gbps mature transimpedance pre-amplifier (TIA) complementrary metal oxide semiconductor (CMOS) chip. The Au layer was deposited on a designed Si platform to form planar waveguide electrode which replaced a part of bonding wire, so it reduced the parasitic parameters of the optoelectronic receiver, and then enhanced high-speed response characteristics and the stability of the hybrid integrated receiver. Finally, a 3 Gbps clear open eye diagram of the hybrid integrated optoelectronic receiver was obtained.

Digital filter polychromator for Thomson scattering applications

NASA Astrophysics Data System (ADS)

Solokha, V.; Kurskiev, G.; Mukhin, E.; Tolstyakov, S.; Babinov, N.; Bazhenov, A.; Bukreev, I.; Dmitriev, A.; Kochergin, M.; Koval, A.; Litvinov, A.; Masyukevich, S.; Razdobarin, A.; Samsonov, D.; Semenov, V.; Solovey, V.; Chernakov, P.; Chernakov, Al; Chernakov, An

2018-02-01

Incoherent Thomson scattering diagnostics (TS) is a proven technique capable of reliable and robust instantaneous measurement of electron temperature (T e) and density (n e) local values in wide area of plasma physics experiments: from hall-effect thrusters to tokamaks and stellarators. The TS cross section is very low (˜ 6.7 × 10-30 m2), and the corresponding TS signals, measured in fusion experiments, are usually of ˜10-15 of incident power. This paper represents 6 (7) channel filter polychromator equipped with avalanche photodiodes and low-noise preamplifiers. The incorporated ADC system (5 GS/s, 12 bit) provides digital optical output preventing acquisition system from electromagnetic interferences. The calibration techniques and T e, n e with corresponding errors measured in Globus-M plasma are given for the digital polychromator test-bench.

S192 multispectral scanner channel 13 electromechanical noise investigation ECP-166

NASA Technical Reports Server (NTRS)

Koumjian, H.

1975-01-01

A review is presented of all data on the multispectral scanner having to do with low frequency noise. The noise is component-induced, either mechanical or electrical or a combination of both. To assist in understanding the source of the noise, several dynamic analyses both structural and electrical were made and are reported. A review is presented of structural resonance test data obtained with the use of an accelerometer and strain gage sensors. Results of an analysis of the natural frequencies of the Dewar leads is included along with an analysis of the S192 cooler and its supporting structure. Other topics discussed include electronic stability of the forward signal, automatic gain control, and the offset control feedback loops as well as the preamplifier which utilized on integrator feedback circuit.

Remote analysis of planetary soils: X-ray diffractometer development

NASA Technical Reports Server (NTRS)

Gregory, J. C.

1973-01-01

A system is described suitable for remote low power mineralogical analysis of lunar, planetary, or asteroid soils. It includes an X-ray diffractometer, fluorescence spectrometer, and sample preparation system. A one Curie Fe-55 source provides a monochromatic X-ray beam of 5.9 keV. Seeman-Bohlin or focusing geometry is employed in the camera, allowing peak detection to proceed simultaneously at all angles and obviating the need for moving parts. The detector system is an array of 500-600 proportional counters with a wire-spacing of 1 mm. An electronics unit comprising preamplifier, postamplifier, window discriminators, and storage flipflops requiring only 3.5 milliwatts was designed and tested. Total instrument power is less than 5 watts. Powder diffraction patterns using a flat breadboard multiwire counter were recorded.

Nano-Electromechanical Systems: Displacement Detection and the Mechanical Single Electron Shuttle

NASA Astrophysics Data System (ADS)

Blick, R. H.; Beil, F. W.; Höhberger, E.; Erbe, A.; Weiss, C.

For an introduction to nano-electromechanical systems we present measurements on nanomechanical resonators operating in the radio frequency range. We discuss in detail two different schemes of displacement detection for mechanical resonators, namely conventional reflection measurements of a probing signal and direct detection by capacitive coupling via a gate electrode. For capacitive detection we employ an on-chip preamplifier, which enables direct measurements of the resonator's disp lacement. We observe that the mechanical quality factor of the resonator depends on the detection technique applied, which is verified in model calculations and report on the detection of sub-harmonics. In the second part we extend our investigations to include transport of single electrons through an electron island on the tip of a nanomachined mechanical pendulum. The pendulum is operated by applying a modulating electromagnetic field in the range of 1 - 200 MHz, leading to mechanical oscillations between two laterally integrated source and drain contacts. Forming tunneling barriers the metallic tip shuttles single electrons from source to drain. The resulting tunneling current shows distinct features corresponding to the discrete mechanical eigenfrequencies of the pendulum. We report on measurements covering the temperature range from 300 K down to 4.2 K. The transport properties of the device are compared in detail to model calculations based on a Master-equation approach.

The front-end electronics of the LSPE-SWIPE experiment

NASA Astrophysics Data System (ADS)

Fontanelli, F.; Biasotti, M.; Bevilacqua, A.; Siccardi, F.

2016-07-01

The SWIPE detector of the Ballon Borne Mission LSPE (see e.g. the contribution of P. de Bernardis et al. in this conference) intends to measure the primordial 'B-mode' polarization of the Cosmic Microwave Background (CMB). For this scope microwave telescopes need sensitive cryogenic bolometers with an overall equivalent noise temperature in the nK range. The detector is a spiderweb bolometer based on transition edge sensor and followed by a SQUID to perform the signal readout. This contribution will concentrate on the design, description and first tests on the front-end electronics which processes the squid output (and controls it). The squid output is first amplified by a very low noise preamplifier based on a discrete JFET input differential architecture followed by a low noise CMOS operational amplifier. Equivalent input noise density is 0.6 nV/Hz and bandwidth extends up to at least 2 MHz. Both devices (JFET and CMOS amplifier) have been tested at liquid nitrogen. The second part of the contribution will discuss design and results of the control electronics, both the flux locked loop for the squid and the slow control chain to monitor and set up the system will be reviewed.

Progress in low light-level InAs detectors- towards Geiger-mode detection

NASA Astrophysics Data System (ADS)

Tan, Chee Hing; Ng, Jo Shien; Zhou, Xinxin; David, John; Zhang, Shiyong; Krysa, Andrey

2017-05-01

InAs avalanche photodiodes (APDs) can be designed such that only electrons are allowed to initiate impact ionization, leading to the lowest possible excess noise factor. Optimization of wet chemical etching and surface passivation produced mesa APDs with bulk dominated dark current and responsivity that are comparable and higher, respectively, than a commercial InAs detector. Our InAs electron-APDs also show high stability with fluctuation of 0.1% when operated at a gain of 11.2 over 60 s. These InAs APDs can detect very weak signal down to 35 photons per pulse. Fabrication of planar InAs by Be implantation produced planar APDs with bulk dominated dark current. Annealing at 550 °C was necessary to remove implantation damage and to activate Be dopants. Due to minimal diffusion of Be, thick depletion of 8 μm was achieved. Since the avalanche gain increases exponentially with the thickness of avalanche region, our planar APD achieved high gain > 300 at 200 K. Our work suggest that both mesa and planar InAs APDs can exhibit high gain. When combined with a suitable preamplifier, single photon detection using InAs electron-APDs could be achieved.

Net current measurements and secondary electron emission characteristics of the Voyager plasma science experiment and their impact on data interpretation

NASA Technical Reports Server (NTRS)

Mcnutt, Ralph L., Jr.

1988-01-01

The Voyager Plasma Science (PLS) instrument is capable of returning integral (DC) current measurements, similar in some respects to measurements made with a Langmuir probe or a retarding potential analyzer, although there are significant differences. The integral measurements were made during a calibration sequence in the solar wind, during Cruise Science Maneuvers, and within the magnetospheres of Jupiter and Saturn by Voyager 1. After the failure of the PLS experiment following the Saturn encounter, that instrument was placed in the DC return mode returning possibly usable data from early 1981 through early 1985. The DC return measurements are difficult to interpret and are above threshold values only for relatively large fluxes; the determination of the measured current level is dependent on the operating temperature of the preamplifiers which further complicates the interpretation. Nevertheless, these measurements can be used to determine the efficiency of the suppressor grid at preventing the loss of secondary electrons off the collector plate. Some DC return measurements have been invaluable in aiding in the interpretation of some electron plasma measurements not previously understood. It is found that electron spectra can be significantly modified by the presence of second generation secondary electrons produced by either first generation secondaries or photoelectrons on the support ring of the negative high voltage modulator grid within the instrument housing.

Solid-state detector system for measuring concentrations of tritiated water vapour and other radioactive gases

NASA Astrophysics Data System (ADS)

Nunes, J. C.; Surette, R. A.; Wood, M. J.

1999-08-01

A detector system was built using a silicon photodiode plus preamplifier and a cesium iodide scintillator plus preamplifier that were commercially available. The potential of the system for measuring concentrations of tritiated water vapour in the presence of other radioactive sources was investigated. For purposes of radiation protection, the sensitivity of the detector system was considered too low for measuring tritiated water vapour concentrations in workplaces such as nuclear power plants. Nevertheless, the spectrometry capability of the system was used successfully to differentiate amongst some radioactive gases in laboratory tests. Although this relatively small system can measure radioactive noble gases as well as tritiated water vapour concentrations, its response to photons remains an issue.

JFET preamplifiers with different reset techniques on detector-grade high-resistivity silicon

NASA Astrophysics Data System (ADS)

Dalla Betta, G. F.; Manghisoni, M.; Ratti, L.; Re, V.; Speziali, V.

2003-10-01

This paper presents the experimental results relevant to JFET charge preamplifiers fabricated in a detector-compatible technology. This fabrication process, developed at the Istituto per la Ricerca Scientifica e Tecnologica (ITC-IRST), Trento, Italy, is being tuned with the aim of integrating a multichannel mixed analog-digital circuit together with semiconductor detectors in a high-resistivity substrate. Possible applications are in the field of medical and industrial imaging, in space and high energy physics experiments. An all-NJFET charge sensitive amplifier, which can use either a resistive or a nonresistive reset in the feedback network, has been tested. The two configurations have been studied, paying particular attention to noise performances, in view of the design of the complete readout channel.

Differential Die-Away Instrument: Report on Neutron Detector Recovery Performance and Proposed Improvements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goodsell, Alison Victoria; Swinhoe, Martyn Thomas; Henzl, Vladimir

2014-09-22

Four helium-3 ( 3He) detector/preamplifier packages (¾”/KM200, DDSI/PDT-A111, DDA/PDT-A111, and DDA/PDT10A) were experimentally tested to determine the deadtime effects at different DT neutron generator output settings. At very high count rates, the ¾”/KM200 package performed best. At high count rates, the ¾”/KM200 and the DDSI/PDT-A111 packages performed very well, with the DDSI/PDT-A111 operating with slightly higher efficiency. All of the packages performed similarly at mid to low count rates. Proposed improvements include using a fast recovery LANL-made dual channel preamplifier, testing smaller diameter 3He tubes, and further investigating quench gases.

A new compact and low cost Langmuir Probe and associated onboard data handling system for CubeSat

NASA Astrophysics Data System (ADS)

Muralikrishna, Polinaya; Domingos, Sinval; Paredes, Andres; Abrahão Dos Santos, Walter

2016-07-01

A new compact and low cost Langmuir Probe and associated onboard data handling system are being developed at Instituto Nacional de Pesquisas Espaciais for launching on board one of the future 2U CubeSat missions. The system is a simplified and compacted version of the Langmuir Probe payloads launched on board several Brazilian SONDA III rockets and also developed for the Brazilian scientific satellites SACI-1 and SACI-2. The onboard data handling system will have the dual functions of preprocessing the data collected by the Langmuir Probe and acting as the interface between the experiment and the on board computer. The Langmuir Probe sensor in the form of two rectangular stainless steel strips of total surface area of approximately 80cm2 will be deployed soon after the injection of the CubeSat into orbit. A sweep voltage varying linearly from 0V to 3.0V in about 1.5 seconds and then remaining fixed at 3.0V for 1 second will be applied to the LP sensor to obtain both the electron density and electron temperature. A high sensitivity preamplifier will be used to convert the sensor current expected to be in the range of a few nano amperes to a few micro amperes into a varying potential. In order to cover the large dynamic range of the expected sensor current the preamplifier output will be further amplified by a logarithmic amplifier before being sampled and sent to the data handling system. The data handling system is projected to handle 8 analog channels and 4 digital words of 8 bits each. The incoming data will be stored in a RAM and later sent to the on board computer using a serial RS422 communication protocol. The interface unit will process the telecommands received from the on board computer. The interface is also projected to do FFT analysis of the LP sensor data and send the averaged FFT spectral amplitudes in place of the original unprocessed data. The system details are presented here.

The NSLS 100 element solid state array detector

PubMed Central

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

2015-01-01

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 < 500000 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 4 mm×4 mm elements laid out on a single piece of ultrahigh 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/D converter, and histogramining 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. PMID:26722135

Imaging electron motion in graphene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhandari, Sagar; Westervelt, Robert M.

A cooled scanning probe microscope (SPM) is an ideal tool to image electronic motion in graphene: the SPM tip acts as a scanning gate, which interacts with the electron gas below. We introduce the technique using our group's previous work on imaging electron flow from a quantum point contact in a GaAs 2DEG and tuning an InAs quantum dot in an InAs/InP nanowire. Carriers in graphene have very different characteristics: electrons and holes travel at a constant speed with no bandgap, and they pass through potential barriers via Klein tunneling. In this paper, we review the extension of SPM imagingmore » techniques to graphene. We image the cyclotron orbits passing between two narrow contacts in a single-atomic-layer graphene device in a perpendicular magnetic field. Magnetic focusing produces a peak in transmission between the contacts when the cyclotron diameter is equal to the contact spacing. The charged SPM tip deflects electrons passing from one contact to the other, changing the transmission when it interrupts the flow. By displaying the change in transmission as the tip is raster scanned above the sample, an image of flow is obtained. In addition, we have developed a complementary technique to image electronic charge using a cooled scanning capacitance microscope (SCM) that uses a sensitive charge preamplifier near the SPM tip to achieve a charge noise level 0.13 e Hz -1/2 with high spatial resolution 100 nm. The cooled SPM and SCM can be used to probe the motion of electrons on the nanoscale in graphene devices.« less

Imaging electron motion in graphene

DOE PAGES

Bhandari, Sagar; Westervelt, Robert M.

2017-01-05

A cooled scanning probe microscope (SPM) is an ideal tool to image electronic motion in graphene: the SPM tip acts as a scanning gate, which interacts with the electron gas below. We introduce the technique using our group's previous work on imaging electron flow from a quantum point contact in a GaAs 2DEG and tuning an InAs quantum dot in an InAs/InP nanowire. Carriers in graphene have very different characteristics: electrons and holes travel at a constant speed with no bandgap, and they pass through potential barriers via Klein tunneling. In this paper, we review the extension of SPM imagingmore » techniques to graphene. We image the cyclotron orbits passing between two narrow contacts in a single-atomic-layer graphene device in a perpendicular magnetic field. Magnetic focusing produces a peak in transmission between the contacts when the cyclotron diameter is equal to the contact spacing. The charged SPM tip deflects electrons passing from one contact to the other, changing the transmission when it interrupts the flow. By displaying the change in transmission as the tip is raster scanned above the sample, an image of flow is obtained. In addition, we have developed a complementary technique to image electronic charge using a cooled scanning capacitance microscope (SCM) that uses a sensitive charge preamplifier near the SPM tip to achieve a charge noise level 0.13 e Hz -1/2 with high spatial resolution 100 nm. The cooled SPM and SCM can be used to probe the motion of electrons on the nanoscale in graphene devices.« less

21 CFR 886.1640 - Ophthalmic preamplifier.

Code of Federal Regulations, 2010 CFR

2010-04-01

... the eyeball after stimulation by light), electrooculography (testing for retinal dysfunction by comparing the standing potential in the front and the back of the eyeball), and electromyography (recording...

21 CFR 886.1640 - Ophthalmic preamplifier.

Code of Federal Regulations, 2014 CFR

2014-04-01

... the eyeball after stimulation by light), electrooculography (testing for retinal dysfunction by comparing the standing potential in the front and the back of the eyeball), and electromyography (recording...

21 CFR 886.1640 - Ophthalmic preamplifier.

Code of Federal Regulations, 2013 CFR

2013-04-01

... the eyeball after stimulation by light), electrooculography (testing for retinal dysfunction by comparing the standing potential in the front and the back of the eyeball), and electromyography (recording...

21 CFR 886.1640 - Ophthalmic preamplifier.

Code of Federal Regulations, 2012 CFR

2012-04-01

... the eyeball after stimulation by light), electrooculography (testing for retinal dysfunction by comparing the standing potential in the front and the back of the eyeball), and electromyography (recording...

21 CFR 886.1640 - Ophthalmic preamplifier.

Code of Federal Regulations, 2011 CFR

2011-04-01

... the eyeball after stimulation by light), electrooculography (testing for retinal dysfunction by comparing the standing potential in the front and the back of the eyeball), and electromyography (recording...

Simulative Analysis of Inter-Satellite Optical Wireless Communication (IsOWC) Link with EDFA

NASA Astrophysics Data System (ADS)

Singh, Mehtab; Singh, Navpreet

2018-04-01

In this paper, simulative analysis and performance comparison of different EDFA (Erbium-doped fiber amplifier) configurations in a 10 Gbps inter-satellite optical wireless communication (IsOWC) link have been reported for a 5,000 km long link and 1,550 nm operating wavelength. The results show that system in which both pre-amplifier and booster amplifier stages are implemented simultaneously outperforms systems with only pre-amplifier and booster amplifier stage. From the results, it can be seen that by deploying a transmission power level of 15 dBm, a link distance of 9,600 km can be achieved with a quality factor of 6.01 dB and BER (Bit error rate) of 1.07×10-9. Also, in this paper, the performance of an 8×7 Gbps WDM-IsOWC link has been reported. The results show that by using both EDFA pre-amplifier and booster amplifier stages, a link distance of 8,000 km for each channel is achievable with desired performance levels (Q≥6 and BER≤10-9). Also, the effect of channel spacing on the performance of WDM-IsOWC link is investigated. The results show that the received signal has acceptable performance levels when the channel spacing is 100 GHz but when the channel spacing is reduced to 80 GHz, the quality of the received signal degrades and link distance decreases.

Compact low-noise preamplifier for noise spectroscopy with biased photodiodes in cargo inspection systems

NASA Astrophysics Data System (ADS)

Benetti, Bob; Langeveld, Willem G. J.

2013-09-01

Noise Spectroscopy, a.k.a. Z-determination by Statistical Count-rate ANalysis (Z-SCAN), is a statistical technique to determine a quantity called the "noise figure" from digitized waveforms of pulses of transmitted x-rays in cargo inspection systems. Depending only on quantities related to the x-ray energies, it measures a characteristic of the transmitted x-ray spectrum, which depends on the atomic number, Z, of the material penetrated. The noise figure can thus be used for material separation. In an 80-detector prototype, scintillators are used with large-area photodiodes biased at 80V and digitized using 50-MSPS 12-bit ADC boards. We present an ultra-compact low-noise preamplifier design, with one high-gain and one low-gain channel per detector for improved dynamic range. To achieve adequate detection sensitivity and spatial resolution each dual-gain preamplifier channel must fit within a 12.7 mm wide circuit board footprint and maintain adequate noise immunity to conducted and radiated interference from adjacent channels. The novel design included iterative SPICE analysis of transient response, dynamic range, frequency response, and noise analysis to optimize the selection and configuration of amplifiers and filter response. We discuss low-noise active and passive components and low-noise techniques for circuit board layout that are essential to achieving the design goals, and how the completed circuit board performed in comparison to the predicted responses.

Performance of room temperature mercuric iodide /HgI2/ detectors in the ultralow-energy X-ray region

NASA Technical Reports Server (NTRS)

Dabrowski, A. J.; Barton, J. B.; Huth, G. C.; Whited, R.; Ortale, C.; Economou, T. E.; Turkevich, A. L.; Iwanczyk, J. S.

1981-01-01

Experiments have been done to study the performance of mercuric iodide (HgI2) detectors in the ultralow-energy X-ray region. Energy resolution values of 245 eV (FWHM) for the Mg K-alpha X-ray line at 1.25 keV and 225 eV (FWHM) for the electronic noise linewidth have been obtained for an HgI2 detector with painted carbon contacts using a pulsed-light feedback preamplifier; the whole system was operated at room temperature. The resolution values in the ultralow-energy region are still limited by electronic noise of the system. In an attempt to minimize X-ray attenuation in the front contact, detectors were prepared with thin evaporated Pd contacts. These detectors show a pronounced low-energy tailing of the photopeak below a few keV, in contrast to the spectra obtained by detectors with carbon contact. An attempt has been made to explain the tailing effect starting with models wich have been proposed to describe similar effects in Ge detectors.

MAROC, a generic photomultiplier readout chip

NASA Astrophysics Data System (ADS)

Blin, S.; Barrillon, P.; de La Taille, C.

2010-12-01

The MAROC ASICs family is dedicated to the readout of 64-channel Multi Anode PMT and similar detectors. Its main roles are to correct the gain spread of MAPMT channels thanks to an individual variable gain preamplifier and to discriminate the input signals (from 50fC i.e 1/3 photo-electron) in order to produce 64 trigger outputs. A multiplexed analog charge output is also available with a dynamic range around 10 pe ( ~ 1.6 pC) and a 12 bit Wilkinson ADC is embedded. Three versions of this chip have been submitted. MAROC 2 is the production version for the ATLAS luminometer and MAROC3 is a version with lower dissipation and significant improvements concerning the charge (30 pe: ~ 5 pC) and trigger (discrimination from 10fC). This third version showed very good characteristics that are presented here.

Development of a High Resolution Liquid Xenon Imaging Telescope for Medium Energy Gamma Ray Astrophysics

NASA Technical Reports Server (NTRS)

Aprile, Elena

1992-01-01

In the third year of the research project, we have (1) tested a 3.5 liter prototype of the Liquid Xenon Time Projection Chamber, (2) used a prototype having a 4.4 cm drift gap to study the charge and energy resolution response of the 3.5 liter chamber, (3) obtained an energy resolution as good as that previously measured by us using chambers with drift gaps of the order of millimeters, (4) observed the induction signals produced by MeV gamma rays, (4) used the 20 hybrid charge sensitive preamplifiers for a nondestructive readout of the electron image on the induction wires, (5) performed extensive Monte Carlo simulations to obtain results on efficiency, background rejection capability, and source flux sensitivity, and (6) developed a reconstruction algorithm for events with multiple interaction points.

A low cost ion beam profile monitor

NASA Astrophysics Data System (ADS)

Godfrey, L.; Hoyes, G. G.; Pairsuwan, W.

1990-09-01

An intercepting multiwire ion beam profile monitor, of thickness 0.9 cm and active area 5 × 5 cm, has been developed for use with the low-intensity deuteron beamline at the Fast Neutron Research Facility (FNRF), Chiang Mai University. It has been used to optimise the transport of a continuous ion beam of current up to 200 μA and kinetic energy up to 140 keV. The monitor enables the determination of the two-dimensional beam profile using closely-spaced samples at 1.5 mm, and the measurement of relative beam current. The design incorporates low material and labour costs, elimination of the need for commercial vacuum feedthroughs, a minimal amount of devoted electronics with no need for preamplifiers, and permits quick insertion of the monitors, wherever needed along the beamline, with minimum disruption to neighbouring elements.

High-performance, multi-faceted research sonar electronics

NASA Astrophysics Data System (ADS)

Moseley, Julian W.

This thesis describes the design, implementation and testing of a research sonar system capable of performing complex applications such as coherent Doppler measurement and synthetic aperture imaging. Specifically, this thesis presents an approach to improve the precision of the timing control and increase the signal-to-noise ratio of an existing research sonar. A dedicated timing control subsystem, and hardware drivers are designed to improve the efficiency of the old sonar's timing operations. A low noise preamplifier is designed to reduce the noise component in the received signal arriving at the input of the system's data acquisition board. Noise analysis, frequency response, and timing simulation data are generated in order to predict the functionality and performance improvements expected when the subsystems are implemented. Experimental data, gathered using these subsys- tems, are presented, and are shown to closely match the simulation results, thus verifying performance.

Preamplifiers for non-contact capacitive biopotential measurements.

PubMed

Peng, GuoChen; Ignjatovic, Zeljko; Bocko, Mark F

2013-01-01

Non-contact biopotential sensing is an attractive measurement strategy for a number of health monitoring applications, primarily the ECG and the EEG. In all such applications a key technical challenge is the design of a low-noise trans-impedance preamplifier for the typically low-capacitance, high source impedance sensing electrodes. In this paper, we compare voltage and charge amplifier designs in terms of their common mode rejection ratio, noise performance, and frequency response. Both amplifier types employ the same operational-transconductance amplifier (OTA), which was fabricated in a 0.35 um CMOS process. The results show that a charge amplifier configuration has advantages for small electrode-to-subject coupling capacitance values (less than 10 pF--typical of noncontact electrodes) and that the voltage amplifier configuration has advantages for electrode capacitances above 10 pF.

Design of an ultra low power CMOS pixel sensor for a future neutron personal dosimeter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Y.; Hu-Guo, C.; Husson, D.

2011-07-01

Despite a continuously increasing demand, neutron electronic personal dosimeters (EPDs) are still far from being completely established because their development is a very difficult task. A low-noise, ultra low power consumption CMOS pixel sensor for a future neutron personal dosimeter has been implemented in a 0.35 {mu}m CMOS technology. The prototype is composed of a pixel array for detection of charged particles, and the readout electronics is integrated on the same substrate for signal processing. The excess electrons generated by an impinging particle are collected by the pixel array. The charge collection time and the efficiency are the crucial pointsmore » of a CMOS detector. The 3-D device simulations using the commercially available Synopsys-SENTAURUS package address the detailed charge collection process. Within a time of 1.9 {mu}s, about 59% electrons created by the impact particle are collected in a cluster of 4 x 4 pixels with the pixel pitch of 80 {mu}m. A charge sensitive preamplifier (CSA) and a shaper are employed in the frond-end readout. The tests with electrical signals indicate that our prototype with a total active area of 2.56 x 2.56 mm{sup 2} performs an equivalent noise charge (ENC) of less than 400 e - and 314 {mu}W power consumption, leading to a promising prototype. (authors)« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khalid, Farah F.; Deptuch, Grzegorz; Shenai, Alpana

Monolithic Active Matrix with Binary Counters (MAMBO) is a counting ASIC designed for detecting and measuring low energy X-rays from 6-12 keV. Each pixel contains analogue functionality implemented with a charge preamplifier, CR-RC{sup 2} shaper and a baseline restorer. It also contains a window comparator which can be trimmed by 4 bit DACs to remove systematic offsets. The hits are registered by a 12 bit ripple counter which is reconfigured as a shift register to serially output the data from the entire ASIC. Each pixel can be tested individually. Two diverse approaches have been used to prevent coupling between themore » detector and electronics in MAMBO III and MAMBO IV. MAMBO III is a 3D ASIC, the bottom ASIC consists of diodes which are connected to the top ASIC using {mu}-bump bonds. The detector is decoupled from the electronics by physically separating them on two tiers and using several metal layers as a shield. MAMBO IV is a monolithic structure which uses a nested well approach to isolate the detector from the electronics. The ASICs are being fabricated using the SOI 0.2 {micro}m OKI process, MAMBO III is 3D bonded at T-Micro and MAMBO IV nested well structure was developed in collaboration between OKI and Fermilab.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khalid, Farah; Deptuch, Grzegorz; Shenai, Alpana

Monolithic Active Matrix with Binary Counters (MAMBO) is a counting ASIC designed for detecting and measuring low energy X-rays from 6-12keV. Each pixel contains analogue functionality implemented with a charge preamplifier, CR-RC{sup 2} shaper and a baseline restorer. It also contains a window comparator which can be trimmed by 4 bit DACs to remove systematic offsets. The hits are registered by a 12 bit ripple counter which is reconfigured as a shift register to serially output the data from the entire ASIC. Each pixel can be tested individually. Two diverse approaches have been used to prevent coupling between the detectormore » and electronics in MAMBO III and MAMBO IV. MAMBO III is a 3D ASIC, the bottom ASIC consists of diodes which are connected to the top ASIC using {mu}-bump bonds. The detector is decoupled from the electronics by physically separating them on two tiers and using several metal layers as a shield. MAMBO IV is a monolithic structure which uses a nested well approach to isolate the detector from the electronics. The ASICs are being fabricated using the SOI 0.2 {micro}m OKI process, MAMBO III is 3D bonded at T-Micro and MAMBO IV nested well structure was developed in collaboration between OKI and Fermilab.« less

The Qweak experimental apparatus

NASA Astrophysics Data System (ADS)

Allison, T.; Anderson, M.; Androić, D.; Armstrong, D. S.; Asaturyan, A.; Averett, T.; Averill, R.; Balewski, J.; Beaufait, J.; Beminiwattha, R. S.; Benesch, J.; Benmokhtar, F.; Bessuille, J.; Birchall, J.; Bonnell, E.; Bowman, J. D.; Brindza, P.; Brown, D. B.; Carlini, R. D.; Cates, G. D.; Cavness, B.; Clark, G.; Cornejo, J. C.; Dusa, S. Covrig; Dalton, M. M.; Davis, C. A.; Dean, D. C.; Deconinck, W.; Diefenbach, J.; Dow, K.; Dowd, J. F.; Dunne, J. A.; Dutta, D.; Duvall, W. S.; Echols, J. R.; Elaasar, M.; Falk, W. R.; Finelli, K. D.; Finn, J. M.; Gaskell, D.; Gericke, M. T. W.; Grames, J.; Gray, V. M.; Grimm, K.; Guo, F.; Hansknecht, J.; Harrison, D. J.; Henderson, E.; Hoskins, J. R.; Ihloff, E.; Johnston, K.; Jones, D.; Jones, M.; Jones, R.; Kargiantoulakis, M.; Kelsey, J.; Khan, N.; King, P. M.; Korkmaz, E.; Kowalski, S.; Kubera, A.; Leacock, J.; Leckey, J. P.; Lee, A. R.; Lee, J. H.; Lee, L.; Liang, Y.; MacEwan, S.; Mack, D.; Magee, J. A.; Mahurin, R.; Mammei, J.; Martin, J. W.; McCreary, A.; McDonald, M. H.; McHugh, M. J.; Medeiros, P.; Meekins, D.; Mei, J.; Michaels, R.; Micherdzinska, A.; Mkrtchyan, A.; Mkrtchyan, H.; Morgan, N.; Musson, J.; Mesick, K. E.; Narayan, A.; Ndukum, L. Z.; Nelyubin, V.; Nuruzzaman; van Oers, W. T. H.; Opper, A. K.; Page, S. A.; Pan, J.; Paschke, K. D.; Phillips, S. K.; Pitt, M. L.; Poelker, M.; Rajotte, J. F.; Ramsay, W. D.; Roberts, W. R.; Roche, J.; Rose, P. W.; Sawatzky, B.; Seva, T.; Shabestari, M. H.; Silwal, R.; Simicevic, N.; Smith, G. R.; Sobczynski, S.; Solvignon, P.; Spayde, D. T.; Stokes, B.; Storey, D. W.; Subedi, A.; Subedi, R.; Suleiman, R.; Tadevosyan, V.; Tobias, W. A.; Tvaskis, V.; Urban, E.; Waidyawansa, B.; Wang, P.; Wells, S. P.; Wood, S. A.; Yang, S.; Zhamkochyan, S.; Zielinski, R. B.

2015-05-01

The Jefferson Lab Qweak experiment determined the weak charge of the proton by measuring the parity-violating elastic scattering asymmetry of longitudinally polarized electrons from an unpolarized liquid hydrogen target at small momentum transfer. A custom apparatus was designed for this experiment to meet the technical challenges presented by the smallest and most precise e → p asymmetry ever measured. Technical milestones were achieved at Jefferson Lab in target power, beam current, beam helicity reversal rate, polarimetry, detected rates, and control of helicity-correlated beam properties. The experiment employed 180 μA of 89% longitudinally polarized electrons whose helicity was reversed 960 times per second. The electrons were accelerated to 1.16 GeV and directed to a beamline with extensive instrumentation to measure helicity-correlated beam properties that can induce false asymmetries. Møller and Compton polarimetry were used to measure the electron beam polarization to better than 1%. The electron beam was incident on a 34.4 cm liquid hydrogen target. After passing through a triple collimator system, scattered electrons between 5.8° and 11.6° were bent in the toroidal magnetic field of a resistive copper-coil magnet. The electrons inside this acceptance were focused onto eight fused silica Cherenkov detectors arrayed symmetrically around the beam axis. A total scattered electron rate of about 7 GHz was incident on the detector array. The detectors were read out in integrating mode by custom-built low-noise pre-amplifiers and 18-bit sampling ADC modules. The momentum transfer Q2=0.025 GeV2 was determined using dedicated low-current (~ 100 pA) measurements with a set of drift chambers before (and a set of drift chambers and trigger scintillation counters after) the toroidal magnet.

Improving Communications Systems

NASA Technical Reports Server (NTRS)

1997-01-01

The Space Shuttle has many communications systems which are used throughout a typical mission. Given that the radio spectrum has become increasingly congested, the ability to hear extremely weak signals requires greater receiver sensitivity. Dryden Flight Research Center approached Angle Linear, a manufacturer of linear radio frequency products and peripherals for communications, to solve the problem. The solution was a receiving preamplifier specially crafted for NASA. Communications with the Space Shuttle are now more reliable,with Dryden being able to also support local missions without purchasing additional equipment. The work has carried over into the Mir Space Station communication support effort and is under evaluation by other NASA centers. The company's preamplifier line was greatly expanded to cover a broader range of frequencies, providing the same sensational improvement to other areas of communication including business, government, trucking, land mobile, cellular and broadcast.

Preamplifiers for non-contact capacitive biopotential measurements*

PubMed Central

Peng, GuoChen; Ignjatovic, Zeljko; Bocko, Mark F.

2014-01-01

Non-contact biopotential sensing is an attractive measurement strategy for a number of health monitoring applications, primarily the ECG and the EEG. In all such applications a key technical challenge is the design of a low-noise trans-impedance preamplifier for the typically low-capacitance, high source impedance sensing electrodes. In this paper, we compare voltage and charge amplifier designs in terms of their common mode rejection ratio, noise performance, and frequency response. Both amplifier types employ the same operational-transconductance amplifier (OTA), which was fabricated in a 0.35um CMOS process. The results show that a charge amplifier configuration has advantages for small electrode-to-subject coupling capacitance values (less than 10 pF - typical of noncontact electrodes) and that the voltage amplifier configuration has advantages for electrode capacitances above 10 pF. PMID:24109979

Cross correlation measurement of low frequency conductivity noise

NASA Astrophysics Data System (ADS)

Jain, Aditya Kumar; Nigudkar, Himanshu; Chakraborti, Himadri; Udupa, Aditi; Gupta, Kantimay Das

2018-04-01

In order to study the low frequency noise(1/f noise)an experimental technique based on cross correlation of two channels is presented. In this method the device under test (DUT)is connected to the two independently powered preamplifiers in parallel. The amplified signals from the two preamplifiers are fed to two channels of a digitizer. Subsequent data processing largelyeliminates the uncorrelated noise of the two channels. This method is tested for various commercial carbon/metal film resistors by measuring equilibrium thermal noise (4kBTR). The method is then modified to study the non-equilibrium low frequency noise of heterostructure samples using fiveprobe configuration. Five contact probes allow two parts of the sample to become two arms of a balanced bridge. This configuration helps in suppressing the effect of power supply fluctuations, bath temperature fluctuations and contact resistances.

Wave detection in acceleration plethysmogram.

PubMed

Ahn, Jae Mok

2015-04-01

Acceleration plethysmogram (APG) obtained from the second derivative of photoplethysmography (PPG) is used to predict risk factors for atherosclerosis with age. This technique is promising for early screening of atherosclerotic pathologies. However, extraction of the wave indices of APG signals measured from the fingertip is challenging. In this paper, the development of a wave detection algorithm including a preamplifier based on a microcontroller that can detect the a, b, c, and d wave indices is proposed. The 4(th) order derivative of a PPG under real measurements of an APG waveform was introduced to clearly separate the components of the waveform, and to improve the rate of successful wave detection. A preamplifier with a Sallen-Key low pass filter and a wave detection algorithm with programmable gain control, mathematical differentials, and a digital IIR notch filter were designed. The frequency response of the digital IIR filter was evaluated, and a pulse train consisting of a specific area in which the wave indices existed was generated. The programmable gain control maintained a constant APG amplitude at the output for varying PPG amplitudes. For 164 subjects, the mean values and standard deviation of the a wave index corresponding to the magnitude of the APG signal were 1,106.45 and ±47.75, respectively. We conclude that the proposed algorithm and preamplifier designed to extract the wave indices of an APG in real-time are useful for evaluating vascular aging in the cardiovascular system in a simple healthcare device.

Digitally controlled high-performance dc SQUID readout electronics for a 304-channel vector magnetometer

NASA Astrophysics Data System (ADS)

Bechstein, S.; Petsche, F.; Scheiner, M.; Drung, D.; Thiel, F.; Schnabel, A.; Schurig, Th

2006-06-01

Recently, we have developed a family of dc superconducting quantum interference device (SQUID) readout electronics for several applications. These electronics comprise a low-noise preamplifier followed by an integrator, and an analog SQUID bias circuit. A highly-compact low-power version with a flux-locked loop bandwidth of 0.3 MHz and a white noise level of 1 nV/√Hz was specially designed for a 304-channel low-Tc dc SQUID vector magnetometer, intended to operate in the new Berlin Magnetically Shielded Room (BMSR-2). In order to minimize the space needed to mount the electronics on top of the dewar and to minimize the power consumption, we have integrated four electronics channels on one 3 cm × 10 cm sized board. Furthermore we embedded the analog components of these four channels into a digitally controlled system including an in-system programmable microcontroller. Four of these integrated boards were combined to one module with a size of 4 cm × 4 cm × 16 cm. 19 of these modules were implemented, resulting in a total power consumption of about 61 W. To initialize the 304 channels and to service the system we have developed software tools running on a laptop computer. By means of these software tools the microcontrollers are fed with all required data such as the working points, the characteristic parameters of the sensors (noise, voltage swing), or the sensor position inside of the vector magnetometer system. In this paper, the developed electronics including the software tools are described, and first results are presented.

Enhancing the noise performance of monolithic microwave integrated circuit-based low noise amplifiers through the use of a discrete preamplifying transistor

NASA Astrophysics Data System (ADS)

McCulloch, Mark A.; Melhuish, Simon J.; Piccirillo, Lucio

2015-01-01

An approach to enhancing the noise performance of an InP monolithic microwave integrated circuit (MMIC)-based low noise amplifiers (LNA) through the use of a discrete 100-nm gate length InP high electron mobility transistor is outlined. This LNA, known as a transistor in front of MMIC (T + MMIC) LNA, possesses a gain in excess of 40 dB and an average noise temperature of 9.4 K across the band 27 to 33 GHz at a physical temperature of 8 K. This compares favorably with 14.5 K for an LNA containing an equivalent MMIC. A simple advanced design system model offering further insights into the operation of the LNA is also presented and the LNA is compared with the current state-of-the-art Planck LFI LNAs.

Noise temperature improvement for magnetic fusion plasma millimeter wave imaging systems.

PubMed

Lai, J; Domier, C W; Luhmann, N C

2014-03-01

Significant progress has been made in the imaging and visualization of magnetohydrodynamic and microturbulence phenomena in magnetic fusion plasmas [B. Tobias et al., Plasma Fusion Res. 6, 2106042 (2011)]. Of particular importance have been microwave electron cyclotron emission imaging and microwave imaging reflectometry systems for imaging T(e) and n(e) fluctuations. These instruments have employed heterodyne receiver arrays with Schottky diode mixer elements directly connected to individual antennas. Consequently, the noise temperature has been strongly determined by the conversion loss with typical noise temperatures of ~60,000 K. However, this can be significantly improved by making use of recent advances in Monolithic Microwave Integrated Circuit chip low noise amplifiers to insert a pre-amplifier in front of the Schottky diode mixer element. In a proof-of-principle design at V-Band (50-75 GHz), significant improvement of noise temperature from the current 60,000 K to measured 4000 K has been obtained.

Study and realization of SI microcalorimeters for high-resolution spectroscopy

NASA Astrophysics Data System (ADS)

Alessandrello, A.; Brofferio, Chiara; Camin, D. V.; Cattadori, C.; Cremonesi, O.; Fiorini, E.; Giuliani, A.; Maglione, A.; Margesin, B.; Nucciotti, A.; Pavan, M.; Pessina, G.; Pignatel, Giorgio U.; Previtali, Ezio; Zanotti, Luigi

1994-09-01

We are developing Si-implanted thermistors to realize high resolution microcalorimeters. We plan to use these devices in an experiment for the determination of the neutrino mass. The measure implies the evaluation of the correct end-point energy of a beta spectrum with a calorimetric approach. Our study is devoted to outline the optimum fabrication process concerning performances and reproducibility. For such reasons we have realized Si thermistors with different concentration of dopant impurities and with different implant geometries. Tests are performed between 4.2 and 1.2 K using a pumped helium cryostat, and selected samples are characterized at very low temperatures in a dilution refrigerator. Good reproducibility of the devices is necessary for producing an array of detectors. At the same time suitable electronics are developed to optimize the detectors preamplifiers link: minimization of the parasitic capacitance is necessary to reduce the integration of signal and to maximize the speed response of the detector.

Cryogenic readout for multiple VUV4 Multi-Pixel Photon Counters in liquid xenon

NASA Astrophysics Data System (ADS)

Arneodo, F.; Benabderrahmane, M. L.; Bruno, G.; Conicella, V.; Di Giovanni, A.; Fawwaz, O.; Messina, M.; Candela, A.; Franchi, G.

2018-06-01

We present the performances and characterization of an array made of S13370-3050CN (VUV4 generation) Multi-Pixel Photon Counters manufactured by Hamamatsu and equipped with a low power consumption preamplifier operating at liquid xenon temperature (∼ 175 K). The electronics is designed for the readout of a matrix of maximum dimension of 8 × 8 individual photosensors and it is based on a single operational amplifier. The detector prototype presented in this paper utilizes the Analog Devices AD8011 current feedback operational amplifier, but other models can be used depending on the application. A biasing correction circuit has been implemented for the gain equalization of photosensors operating at different voltages. The results show single photon detection capability making this device a promising choice for future generation of large scale dark matter detectors based on liquid xenon, such as DARWIN.

MOSFET's for Cryogenic Amplifiers

NASA Technical Reports Server (NTRS)

Dehaye, R.; Ventrice, C. A.

1987-01-01

Study seeks ways to build transistors that function effectively at liquid-helium temperatures. Report discusses physics of metaloxide/semiconductor field-effect transistors (MOSFET's) and performances of these devices at cryogenic temperatures. MOSFET's useful in highly sensitive cryogenic preamplifiers for infrared astronomy.

Design and testing of a low impedance transceiver circuit for nitrogen-14 nuclear quadrupole resonance.

PubMed

Sato-Akaba, Hideo

2014-01-01

A low impedance transceiver circuit consisting of a transmit-receive switch circuit, a class-D amplifier and a transimpedance amplifier (TIA) was newly designed and tested for a nitrogen-14 NQR. An NQR signal at 1.37MHz from imidazole was successfully observed with the dead time of ~85µs under the high Q transmission (Q~120) and reception (Q~140). The noise performance of the low impedance TIA with an NQR probe was comparable with a commercial low noise 50Ω amplifier (voltage input noise: 0.25 nV/Hz) which was also connected to the probe. The protection voltage for the pre-amplifier using the low impedance transceiver was ~10 times smaller than that for the pre-amplifier using a 50Ω conventional transceiver, which is suitable for NQR remote sensing applications. Copyright © 2014 Elsevier Inc. All rights reserved.

Detailed noise statistics for an optically preamplified direct detection receiver

NASA Astrophysics Data System (ADS)

Danielsen, Soeren Lykke; Mikkelsen, Benny; Durhuus, Terji; Joergensen, Carsten; Stubkjaer, Kristian E.

We describe the exact statistics of an optically preamplified direct detection receiver by means of the moment generating function. The theory allows an arbitrary shaped electrical filter in the receiver circuit. The moment generating function (MGF) allows for a precise calculation of the error rate by using the inverse Fast Fourier transform (FFT). The exact results are compared with the usual Gaussian approximation (GA), the saddlepoint approximation (SAP) and the modified Chernoff bound (MCB). This comparison shows that the noise is not Gaussian distributed for all values of the optical amplifier gain. In the region from 20-30 dB gain, calculations shows that the GA underestimates the receiver sensitivity while the SAP is very close to the results of our exact model. Using the MGF derived in the article we then find the optimal bandwidth of the electrical filter in the receiver circuit and calculate the sensitivity degradation due to inter symbol interference (ISI).

MSDS sky reference and preamplifier study

NASA Technical Reports Server (NTRS)

Larsen, L.; Stewart, S.; Lambeck, P.

1974-01-01

The major goals in re-designing the Multispectral Scanner and Data System (MSDS) sky reference are: (1) to remove the sun-elevation angle and aircraft-attitude angle dependence from the solar-sky illumination measurement, and (2) to obtain data on the optical state of the atmosphere. The present sky reference is dependent on solar elevation and provides essentially no information on important atmospheric parameters. Two sky reference designs were tested. One system is built around a hyperbolic mirror and the reflection approach. A second approach to a sky reference utilizes a fish-eye lens to obtain a 180 deg field of view. A detailed re-design of the present sky reference around the fish-eye approach, even with its limitations, is recommended for the MSDS system. A preamplifier study was undertaken to find ways of improving the noise-equivalent reflectance by reducing the noise level for silicon detector channels on the MSDS.

High-resolution ionization detector and array of such detectors

DOEpatents

McGregor, Douglas S [Ypsilanti, MI; Rojeski, Ronald A [Pleasanton, CA

2001-01-16

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

Low-power low-noise mixed-mode VLSI ASIC for infinite dynamic range imaging applications

NASA Astrophysics Data System (ADS)

Turchetta, Renato; Hu, Y.; Zinzius, Y.; Colledani, C.; Loge, A.

1998-11-01

Solid state solutions for imaging are mainly represented by CCDs and, more recently, by CMOS imagers. Both devices are based on the integration of the total charge generated by the impinging radiation, with no processing of the single photon information. The dynamic range of these devices is intrinsically limited by the finite value of noise. Here we present the design of an architecture which allows efficient, in-pixel, noise reduction to a practically zero level, thus allowing infinite dynamic range imaging. A detailed calculation of the dynamic range is worked out, showing that noise is efficiently suppressed. This architecture is based on the concept of single-photon counting. In each pixel, we integrate both the front-end, low-noise, low-power analog part and the digital part. The former consists of a charge preamplifier, an active filter for optimal noise bandwidth reduction, a buffer and a threshold comparator, and the latter is simply a counter, which can be programmed to act as a normal shift register for the readout of the counters' contents. Two different ASIC's based on this concept have been designed for different applications. The first one has been optimized for silicon edge-on microstrips detectors, used in a digital mammography R and D project. It is a 32-channel circuit, with a 16-bit binary static counter.It has been optimized for a relatively large detector capacitance of 5 pF. Noise has been measured to be equal to 100 + 7*Cd (pF) electron rms with the digital part, showing no degradation of the noise performances with respect to the design values. The power consumption is 3.8mW/channel for a peaking time of about 1 microsecond(s) . The second circuit is a prototype for pixel imaging. The total active area is about (250 micrometers )**2. The main differences of the electronic architecture with respect to the first prototype are: i) different optimization of the analog front-end part for low-capacitance detectors, ii) in- pixel 4-bit comparator-offset compensation, iii) 15-bit pseudo-random counter. The power consumption is 255 (mu) W/channel for a peaking time of 300 ns and an equivalent noise charge of 185 + 97*Cd electrons rms. Simulation and experimental result as well as imaging results will be presented.

Low-Cutoff, High-Pass Digital Filtering of Neural Signals

NASA Technical Reports Server (NTRS)

Mojarradi,Mohammad; Johnson, Travis; Ortiz, Monico; Cunningham, Thomas; Andersen, Richard

2004-01-01

The figure depicts the major functional blocks of a system, now undergoing development, for conditioning neural signals acquired by electrodes implanted in a brain. The overall functions to be performed by this system can be summarized as preamplification, multiplexing, digitization, and high-pass filtering. Other systems under development for recording neural signals typically contain resistor-capacitor analog low-pass filters characterized by cutoff frequencies in the vicinity of 100 Hz. In the application for which this system is being developed, there is a requirement for a cutoff frequency of 5 Hz. Because the resistors needed to obtain such a low cutoff frequency would be impractically large, it was decided to perform low-pass filtering by use of digital rather than analog circuitry. In addition, it was decided to timemultiplex the digitized signals from the multiple input channels into a single stream of data in a single output channel. The signal in each input channel is first processed by a preamplifier having a voltage gain of approximately 50. Embedded in each preamplifier is a low-pass anti-aliasing filter having a cutoff frequency of approximately 10 kHz. The anti-aliasing filters make it possible to couple the outputs of the preamplifiers to the input ports of a multiplexer. The output of the multiplexer is a single stream of time-multiplexed samples of analog signals. This stream is processed by a main differential amplifier, the output of which is sent to an analog-to-digital converter (ADC). The output of the ADC is sent to a digital signal processor (DSP).

A CMOS frontend chip for implantable neural recording with wide voltage supply range

NASA Astrophysics Data System (ADS)

Jialin, Liu; Xu, Zhang; Xiaohui, Hu; Yatao, Guo; Peng, Li; Ming, Liu; Bin, Li; Hongda, Chen

2015-10-01

A design for a CMOS frontend integrated circuit (chip) for neural signal acquisition working at wide voltage supply range is presented in this paper. The chip consists of a preamplifier, a serial instrumental amplifier (IA) and a cyclic analog-to-digital converter (CADC). The capacitive-coupled and capacitive-feedback topology combined with MOS-bipolar pseudo-resistor element is adopted in the preamplifier to create a -3 dB upper cut-off frequency less than 1 Hz without using a ponderous discrete device. A dual-amplifier instrumental amplifier is used to provide a low output impedance interface for ADC as well as to boost the gain. The preamplifier and the serial instrumental amplifier together provide a midband gain of 45.8 dB and have an input-referred noise of 6.7 μVrms integrated from 1 Hz to 5 kHz. The ADC digitizes the amplified signal at 12-bits precision with a highest sampling rate of 130 kS/s. The measured effective number of bits (ENOB) of the ADC is 8.7 bits. The entire circuit draws 165 to 216 μA current from the supply voltage varied from 1.34 to 3.3 V. The prototype chip is fabricated in the 0.18-μm CMOS process and occupies an area of 1.23 mm2 (including pads). In-vitro recording was successfully carried out by the proposed frontend chip. Project supported by the National Natural Science Foundation of China (Nos. 61474107, 61372060, 61335010, 61275200, 61178051) and the Key Program of the Chinese Academy of Sciences (No. KJZD-EW-L11-01).

Biomedical sensing and display concept improves brain wave monitoring

NASA Technical Reports Server (NTRS)

Trent, R. L.

1970-01-01

Concept for increasing effectiveness of biomedical sensing and display promises greater monitoring capability while lessening high skill requirements in operating personnel. New concept overcomes deficiencies of current system by employing increased number of probes and microelectronic preamplifiers.

Electrometer Amplifier With Overload Protection

NASA Technical Reports Server (NTRS)

Woeller, F. H.; Alexander, R.

1986-01-01

Circuit features low noise, input offset, and high linearity. Input preamplifier includes input-overload protection and nulling circuit to subtract dc offset from output. Prototype dc amplifier designed for use with ion detector has features desirable in general laboratory and field instrumentation.

VEGA: A low-power front-end ASIC for large area multi-linear X-ray silicon drift detectors: Design and experimental characterization

NASA Astrophysics Data System (ADS)

Ahangarianabhari, Mahdi; Macera, Daniele; Bertuccio, Giuseppe; Malcovati, Piero; Grassi, Marco

2015-01-01

We present the design and the first experimental characterization of VEGA, an Application Specific Integrated Circuit (ASIC) designed to read out large area monolithic linear Silicon Drift Detectors (SDD's). VEGA consists of an analog and a digital/mixed-signal section to accomplish all the functionalities and specifications required for high resolution X-ray spectroscopy in the energy range between 500 eV and 50 keV. The analog section includes a charge sensitive preamplifier, a shaper with 3-bit digitally selectable shaping times from 1.6 μs to 6.6 μs and a peak stretcher/sample-and-hold stage. The digital/mixed-signal section includes an amplitude discriminator with coarse and fine threshold level setting, a peak discriminator and a logic circuit to fulfill pile-up rejection, signal sampling, trigger generation, channel reset and the preamplifier and discriminators disabling functionalities. A Serial Peripherical Interface (SPI) is integrated in VEGA for loading and storing all configuration parameters in an internal register within few microseconds. The VEGA ASIC has been designed and manufactured in 0.35 μm CMOS mixed-signal technology in single and 32 channel versions with dimensions of 200 μm×500 μm per channel. A minimum intrinsic Equivalent Noise Charge (ENC) of 12 electrons r.m.s. at 3.6 μs peaking time and room temperature is measured and the linearity error is between -0.9% and +0.6% in the whole input energy range. The total power consumption is 481 μW and 420 μW per channel for the single and 32 channels version, respectively. A comparison with other ASICs for X-ray SDD's shows that VEGA has a suitable low noise and offers high functionality as ADC-ready signal processing but at a power consumption that is a factor of four lower than other similar existing ASICs.

MEDUSA-32: A low noise, low power silicon strip detector front-end electronics, for space applications

NASA Astrophysics Data System (ADS)

Cicuttin, Andres; Colavita, Alberto; Cerdeira, Alberto; Fratnik, Fabio; Vacchi, Andrea

1997-02-01

In this report we describe a mixed analog-digital integrated circuit (IC) designed as the front-end electronics for silicon strip-detectors for space applications. In space power consumption, compactness and robustness become critical constraints for a pre-amplifier design. The IC is a prototype with 32 complete channels, and it is intended for a large area particle tracker of a new generation of gamma ray telescopes. Each channel contains a charge sensitive amplifier, a pulse shaper, a discriminator and two digital buffers. The reference trip point of the discriminator is adjustable. This chip also has a custom PMOSFET transistor per channel, included in order to provide the high dynamic resistance needed to reverse-bias the strip diode. The digital part of the chip is used to store and serially shift out the state of the channels. There is also a storage buffer that allows the disabling of non-functioning channels if it is required by the data acquisition system. An input capacitance of 30 pF introduced at the input of the front-end produces less than 1000 electrons of RMS equivalent noise charge (ENC), for a total power dissipation of only 60 μW per channel. The chip was made using Orbit's 1.2 μm double poly, double metal n-well low noise CMOS process. The dimensions of the IC are 2400 μm × 8840 μm.

DC-based magnetic field controller

DOEpatents

Kotter, Dale K.; Rankin, Richard A.; Morgan, John P,.

1994-01-01

A magnetic field controller for laboratory devices and in particular to dc operated magnetic field controllers for mass spectrometers, comprising a dc power supply in combination with improvements to a hall probe subsystem, display subsystem, preamplifier, field control subsystem, and an output stage.

Bio-isolated DC operational amplifier

NASA Technical Reports Server (NTRS)

Lee, R. D.

1974-01-01

Possibility of shocks from leakage currents can be reduced by use of isolated preamplifiers. Amplifier consists of battery-powered operational amplifier coupled by means of light-emitting diodes to another amplifier which may be grounded and operated from ac power mains or separate battery supply.

A Gain-Programmable Transit-Time-Stable and Temperature-Stable PMT Voltage Divider

NASA Astrophysics Data System (ADS)

Liu, Yaqiang; Li, Hongdi; Wang, Yu; Xing, Tao; Xie, Shuping; Uribe, J.; Baghaei, H.; Ramirez, R.; Kim, Soonseok; Wong, Wai-Hoi

2004-10-01

A gain-programmable, transit-time-stable, temperature-stable photomultiplier (PMT) voltage divider design is described in this paper. The signal-to-noise ratio can be increased by changing a PMT gain directly instead of adjusting the gain of the preamplifier. PMT gain can be changed only by adjusting the voltages for the dynodes instead of changing the total high voltage between the anode and the photocathode, which can cause a significant signal transit-time variation that cannot be accepted by an application with a critical timing requirement, such as positron emission tomography (PET) or time-of-flight (TOF) detection/PET. The dynode voltage can be controlled by a digital analog converter isolated with a linear optocoupler. The optocoupler consists of an infrared light emission diode (LED) optically coupled with two phototransistors, and one is used in a servo feedback circuit to control the LED drive current for compensating temperature characteristics. The results showed that a six times gain range could be achieved; the gain drift was <0.5% over a 20/spl deg/C temperature range; 250 ps transit-time variation was measured over the entire gain range. A compact print circuit board (PCB) for the voltage divider integrated with a fixed-gain preamplifier has been designed and constructed. It can save about $30 per PMT channel compared with a commercial PMT voltage divider along with a variable gain amplifier. The preamplifier can be totally disabled, therefore in a system with a large amount of PMTs, only one channel can be enabled for calibrating the PMT gain. This new PMT voltage divider design is being applied to our animal PET camera and TOF/PET research.

Design and characterization of high precision in-pixel discriminators for rolling shutter CMOS pixel sensors with full CMOS capability

NASA Astrophysics Data System (ADS)

Fu, Y.; Hu-Guo, C.; Dorokhov, A.; Pham, H.; Hu, Y.

2013-07-01

In order to exploit the ability to integrate a charge collecting electrode with analog and digital processing circuitry down to the pixel level, a new type of CMOS pixel sensors with full CMOS capability is presented in this paper. The pixel array is read out based on a column-parallel read-out architecture, where each pixel incorporates a diode, a preamplifier with a double sampling circuitry and a discriminator to completely eliminate analog read-out bottlenecks. The sensor featuring a pixel array of 8 rows and 32 columns with a pixel pitch of 80 μm×16 μm was fabricated in a 0.18 μm CMOS process. The behavior of each pixel-level discriminator isolated from the diode and the preamplifier was studied. The experimental results indicate that all in-pixel discriminators which are fully operational can provide significant improvements in the read-out speed and the power consumption of CMOS pixel sensors.

Optimization of a low noise detection circuit for probing the structure of damage cascades with IBIC

DOE PAGES

Auden, Elizabeth C.; Doyle, Barney L.; Bielejec, Edward; ...

2015-06-18

Optimal detector / pre-amplifier combinations have been identified for the use of light ion IBIC (ion beam induced charge) to probe the physical structure of electrically active defects in damage cascades caused by heavy ion implantation. The ideal detector must have a sufficiently thin dead layer that incident ions will produce the majority of damage cascades in the depletion region of the detector rather than the dead layer. Detector and circuit noise must be low enough to detect the implantation of a single heavy ion as well as the decrease in the light ion IBIC signal caused by Shockley-Read-Hall recombinationmore » when the beam scans regions of the detector damaged by the heavy ion. The IBIC signals from three detectors irradiated with 750 keV He⁺ ions are measured with commercial and bespoke charge sensitive pre-amplifiers to identify the combination with the lowest noise.« less

Amplifiers dedicated for large area SiC photodiodes

NASA Astrophysics Data System (ADS)

Doroz, P.; Duk, M.; Korwin-Pawlowski, M. L.; Borecki, M.

2016-09-01

Large area SiC photodiodes find applications in optoelectronic sensors working at special conditions. These conditions include detection of UV radiation in harsh environment. Moreover, the mentioned sensors have to be selective and resistant to unwanted signals. For this purpose, the modulation of light at source unit and the rejection of constant current and low frequency component of signal at detector unit are used. The popular frequency used for modulation in such sensor is 1kHz. The large area photodiodes are characterized by a large capacitance and low shunt resistance that varies with polarization of the photodiode and can significantly modify the conditions of signal pre-amplification. In this paper two pre-amplifiers topology are analyzed: the transimpedance amplifier and the non-inverting voltage to voltage amplifier with negative feedback. The feedback loops of both pre-amplifiers are equipped with elements used for initial constant current and low frequency signals rejections. Both circuits are analyzed and compared using simulation and experimental approaches.

Prospects for charge sensitive amplifiers in scaled CMOS

NASA Astrophysics Data System (ADS)

O'Connor, Paul; De Geronimo, Gianluigi

2002-03-01

Due to its low cost and flexibility for custom design, monolithic CMOS technology is being increasingly employed in charge preamplifiers across a broad range of applications, including both scientific research and commercial products. The associated detectors have capacitances ranging from a few tens of fF to several hundred pF. Applications call for pulse shaping from tens of ns to tens of μs, and constrain the available power per channel from tens of μW to tens of mW. At the same time a new technology generation, with changed device parameters, appears every 2 years or so. The optimum design of the front-end circuitry is examined taking into account submicron device characteristics, weak inversion operation, the reset system, and power supply scaling. Experimental results from recent prototypes will be presented. We will also discuss the evolution of preamplifier topologies and anticipated performance limits as CMOS technology scales down to the 0.1 μm/1.0 V generation in 2006.

A readout circuit dedicated for the detection of chemiluminescence using a silicon photomultiplier

NASA Astrophysics Data System (ADS)

Baszczyk, M.; Dorosz, P.; Mik, L.; Kucewicz, W.; Reczynski, W.; Sapor, M.

2018-05-01

A readout circuit dedicated for the detection of the chemiluminescence phenomenon using a silicon photomultiplier (SiPM) is presented. During chemiluminescence, light is generated as a result of chemical reaction. Chemiluminescence is used in many applications within medicine, chemistry, biology and biotechnology, and is one of the most important sensing techniques in biomedical science and clinical medicine. The front-end electronics consist of a preamplifier and a fast shaper—this produces pulses, the peaking time which is 3.6 ns for a single photon and the FWHM is 3.8 ns. The system has been optimised to measure chemiluminescence—it is sensitive at the level of single photons, it generates a low number of overlapping pulses and is accurate. Two methods of signal detection are analysed and compared: the counting of events and amplitude detection. The relationship between the chemiluminescence light intensity and the concentration of the chemical compound (luminol) is linear in the range of the tested concentrations and has strong linearity parameters and low prediction intervals.

Noise temperature improvement for magnetic fusion plasma millimeter wave imaging systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lai, J.; Domier, C. W.; Luhmann, N. C.

2014-03-15

Significant progress has been made in the imaging and visualization of magnetohydrodynamic and microturbulence phenomena in magnetic fusion plasmas [B. Tobias et al., Plasma Fusion Res. 6, 2106042 (2011)]. Of particular importance have been microwave electron cyclotron emission imaging and microwave imaging reflectometry systems for imaging T{sub e} and n{sub e} fluctuations. These instruments have employed heterodyne receiver arrays with Schottky diode mixer elements directly connected to individual antennas. Consequently, the noise temperature has been strongly determined by the conversion loss with typical noise temperatures of ∼60 000 K. However, this can be significantly improved by making use of recent advancesmore » in Monolithic Microwave Integrated Circuit chip low noise amplifiers to insert a pre-amplifier in front of the Schottky diode mixer element. In a proof-of-principle design at V-Band (50–75 GHz), significant improvement of noise temperature from the current 60 000 K to measured 4000 K has been obtained.« less

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

NASA Astrophysics Data System (ADS)

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

1990-06-01

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

Silicon avalanche photodiode detector circuit for Nd:YAG laser scattering

NASA Astrophysics Data System (ADS)

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

1990-10-01

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

Novel active signal compression in low-noise analog readout at future X-ray FEL facilities

NASA Astrophysics Data System (ADS)

Manghisoni, M.; Comotti, D.; Gaioni, L.; Lodola, L.; Ratti, L.; Re, V.; Traversi, G.; Vacchi, C.

2015-04-01

This work presents the design of a low-noise front-end implementing a novel active signal compression technique. This feature can be exploited in the design of analog readout channels for application to the next generation free electron laser (FEL) experiments. The readout architecture includes the low-noise charge sensitive amplifier (CSA) with dynamic signal compression, a time variant shaper used to process the signal at the preamplifier output and a 10-bit successive approximation register (SAR) analog-to-digital converter (ADC). The channel will be operated in such a way to cope with the high frame rate (exceeding 1 MHz) foreseen for future XFEL machines. The choice of a 65 nm CMOS technology has been made in order to include all the building blocks in the target pixel pitch of 100 μm. This work has been carried out in the frame of the PixFEL Project funded by the Istituto Nazionale di Fisica Nucleare (INFN), Italy.

DNA-based identification of spices: DNA isolation, whole genome amplification, and polymerase chain reaction.

PubMed

Focke, Felix; Haase, Ilka; Fischer, Markus

2011-01-26

Usually spices are identified morphologically using simple methods like magnifying glasses or microscopic instruments. On the other hand, molecular biological methods like the polymerase chain reaction (PCR) enable an accurate and specific detection also in complex matrices. Generally, the origins of spices are plants with diverse genetic backgrounds and relationships. The processing methods used for the production of spices are complex and individual. Consequently, the development of a reliable DNA-based method for spice analysis is a challenging intention. However, once established, this method will be easily adapted to less difficult food matrices. In the current study, several alternative methods for the isolation of DNA from spices have been developed and evaluated in detail with regard to (i) its purity (photometric), (ii) yield (fluorimetric methods), and (iii) its amplifiability (PCR). Whole genome amplification methods were used to preamplify isolates to improve the ratio between amplifiable DNA and inhibiting substances. Specific primer sets were designed, and the PCR conditions were optimized to detect 18 spices selectively. Assays of self-made spice mixtures were performed to proof the applicability of the developed methods.

Binary-selectable detector holdoff circuit

NASA Technical Reports Server (NTRS)

Kadrmas, K. A.

1974-01-01

High-speed switching circuit protects detectors from sudden, extremely-intense backscattered radiation that results from short-range atmospheric dust layers, or low-level clouds, entering laser/radar field of view. Function of circuit is to provide computer-controlled switching of photodiode detector, preamplifier power-supply voltages, in approximately 10 nanoseconds.

Determination of the Pressure Equivalent Noise Signal of Vector Sensors in a Hybrid Array

DTIC Science & Technology

2012-12-01

pressure sensors for acoustic signals raises the possibility of increased sonar array performance with smaller arrays. Caulk successfully...contribution of the preamplifier in the circuit was estimated as . So the Johnson noise of the sensor wires themselves is expected to dominate

Derivation of the Statistical Distribution of the Mass Peak Centroids of Mass Spectrometers Employing Analog-to-Digital Converters and Electron Multipliers

DOE PAGES

Ipsen, Andreas

2017-02-03

Here, the mass peak centroid is a quantity that is at the core of mass spectrometry (MS). However, despite its central status in the field, models of its statistical distribution are often chosen quite arbitrarily and without attempts at establishing a proper theoretical justification for their use. Recent work has demonstrated that for mass spectrometers employing analog-to-digital converters (ADCs) and electron multipliers, the statistical distribution of the mass peak intensity can be described via a relatively simple model derived essentially from first principles. Building on this result, the following article derives the corresponding statistical distribution for the mass peak centroidsmore » of such instruments. It is found that for increasing signal strength, the centroid distribution converges to a Gaussian distribution whose mean and variance are determined by physically meaningful parameters and which in turn determine bias and variability of the m/z measurements of the instrument. Through the introduction of the concept of “pulse-peak correlation”, the model also elucidates the complicated relationship between the shape of the voltage pulses produced by the preamplifier and the mean and variance of the centroid distribution. The predictions of the model are validated with empirical data and with Monte Carlo simulations.« less

Derivation of the Statistical Distribution of the Mass Peak Centroids of Mass Spectrometers Employing Analog-to-Digital Converters and Electron Multipliers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ipsen, Andreas

Here, the mass peak centroid is a quantity that is at the core of mass spectrometry (MS). However, despite its central status in the field, models of its statistical distribution are often chosen quite arbitrarily and without attempts at establishing a proper theoretical justification for their use. Recent work has demonstrated that for mass spectrometers employing analog-to-digital converters (ADCs) and electron multipliers, the statistical distribution of the mass peak intensity can be described via a relatively simple model derived essentially from first principles. Building on this result, the following article derives the corresponding statistical distribution for the mass peak centroidsmore » of such instruments. It is found that for increasing signal strength, the centroid distribution converges to a Gaussian distribution whose mean and variance are determined by physically meaningful parameters and which in turn determine bias and variability of the m/z measurements of the instrument. Through the introduction of the concept of “pulse-peak correlation”, the model also elucidates the complicated relationship between the shape of the voltage pulses produced by the preamplifier and the mean and variance of the centroid distribution. The predictions of the model are validated with empirical data and with Monte Carlo simulations.« less

Determination of electron beam polarization using electron detector in Compton polarimeter with less than 1% statistical and systematic uncertainty

DOE Office of Scientific and Technical Information (OSTI.GOV)

Narayan, Amrendra

2015-05-01

The Q-weak experiment aims to measure the weak charge of proton with a precision of 4.2%. The proposed precision on weak charge required a 2.5% measurement of the parity violating asymmetry in elastic electron - proton scattering. Polarimetry was the largest experimental contribution to this uncertainty and a new Compton polarimeter was installed in Hall C at Jefferson Lab to make the goal achievable. In this polarimeter the electron beam collides with green laser light in a low gain Fabry-Perot Cavity; the scattered electrons are detected in 4 planes of a novel diamond micro strip detector while the back scatteredmore » photons are detected in lead tungstate crystals. This diamond micro-strip detector is the first such device to be used as a tracking detector in a nuclear and particle physics experiment. The diamond detectors are read out using custom built electronic modules that include a preamplifier, a pulse shaping amplifier and a discriminator for each detector micro-strip. We use field programmable gate array based general purpose logic modules for event selection and histogramming. Extensive Monte Carlo simulations and data acquisition simulations were performed to estimate the systematic uncertainties. Additionally, the Moller and Compton polarimeters were cross calibrated at low electron beam currents using a series of interleaved measurements. In this dissertation, we describe all the subsystems of the Compton polarimeter with emphasis on the electron detector. We focus on the FPGA based data acquisition system built by the author and the data analysis methods implemented by the author. The simulations of the data acquisition and the polarimeter that helped rigorously establish the systematic uncertainties of the polarimeter are also elaborated, resulting in the first sub 1% measurement of low energy (?1 GeV) electron beam polarization with a Compton electron detector. We have demonstrated that diamond based micro-strip detectors can be used for tracking in a high radiation environment and it has enabled us to achieve the desired precision in the measurement of the electron beam polarization which in turn has allowed the most precise determination of the weak charge of the proton.« less

Determination of electron beam polarization using electron detector in Compton polarimeter with less than 1% statistical and systematic uncertainty

NASA Astrophysics Data System (ADS)

Narayan, Amrendra

The Q-weak experiment aims to measure the weak charge of proton with a precision of 4.2%. The proposed precision on weak charge required a 2.5% measurement of the parity violating asymmetry in elastic electron - proton scattering. Polarimetry was the largest experimental contribution to this uncertainty and a new Compton polarimeter was installed in Hall C at Jefferson Lab to make the goal achievable. In this polarimeter the electron beam collides with green laser light in a low gain Fabry-Perot Cavity; the scattered electrons are detected in 4 planes of a novel diamond micro strip detector while the back scattered photons are detected in lead tungstate crystals. This diamond micro-strip detector is the first such device to be used as a tracking detector in a nuclear and particle physics experiment. The diamond detectors are read out using custom built electronic modules that include a preamplifier, a pulse shaping amplifier and a discriminator for each detector micro-strip. We use field programmable gate array based general purpose logic modules for event selection and histogramming. Extensive Monte Carlo simulations and data acquisition simulations were performed to estimate the systematic uncertainties. Additionally, the Moller and Compton polarimeters were cross calibrated at low electron beam currents using a series of interleaved measurements. In this dissertation, we describe all the subsystems of the Compton polarimeter with emphasis on the electron detector. We focus on the FPGA based data acquisition system built by the author and the data analysis methods implemented by the author. The simulations of the data acquisition and the polarimeter that helped rigorously establish the systematic uncertainties of the polarimeter are also elaborated, resulting in the first sub 1% measurement of low energy (~1GeV) electron beam polarization with a Compton electron detector. We have demonstrated that diamond based micro-strip detectors can be used for tracking in a high radiation environment and it has enabled us to achieve the desired precision in the measurement of the electron beam polarization which in turn has allowed the most precise determination of the weak charge of the proton.

Precision tracking with a single gaseous pixel detector

NASA Astrophysics Data System (ADS)

Tsigaridas, S.; van Bakel, N.; Bilevych, Y.; Gromov, V.; Hartjes, F.; Hessey, N. P.; de Jong, P.; Kluit, R.

2015-09-01

The importance of micro-pattern gaseous detectors has grown over the past few years after successful usage in a large number of applications in physics experiments and medicine. We develop gaseous pixel detectors using micromegas-based amplification structures on top of CMOS pixel readout chips. Using wafer post-processing we add a spark-protection layer and a grid to create an amplification region above the chip, allowing individual electrons released above the grid by the passage of ionising radiation to be recorded. The electron creation point is measured in 3D, using the pixel position for (x, y) and the drift time for z. The track can be reconstructed by fitting a straight line to these points. In this work we have used a pixel-readout-chip which is a small-scale prototype of Timepix3 chip (designed for both silicon and gaseous detection media). This prototype chip has several advantages over the existing Timepix chip, including a faster front-end (pre-amplifier and discriminator) and a faster TDC which reduce timewalk's contribution to the z position error. Although the chip is very small (sensitive area of 0.88 × 0.88mm2), we have built it into a detector with a short drift gap (1.3 mm), and measured its tracking performance in an electron beam at DESY. We present the results obtained, which lead to a significant improvement for the resolutions with respect to Timepix-based detectors.

A 2385 MHz, 2-stage low noise amplifier design

NASA Technical Reports Server (NTRS)

Sifri, Jack D.

1986-01-01

This article shows the design aspects of a 2.385 GHz low noise preamplifier with a .7 dB noise figure and 16.5 dB gain using the NE 67383 FET. The design uses a unique method in matching the input which achieves optimum noise figure and unconditional stability.

Chaotic LIDAR for Naval Applications

DTIC Science & Technology

2012-09-30

experimental output power is shown in the following figure. Fabry-Perot Fiber Laser PD ^^ /--"^ —► -(YDF\\ {SMFV X FBG 1 0 r utput FBG 70 60 3...Right: Output power versus pump power. (PD: Pump Diode; FBG : Fiber Braggs Grating; YDF: Ytterbium Doped Fiber; SMF: Single Mode Fiber.) Preamplifier

Portable Intelligent Tritium in Air Monitor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Purghel, L.; Calin, M.R.; Bartos, D.

2005-07-15

The tritium detection method used for this monitor is original, patented in Romania. The detection unit consists of a single ionization chamber, a special fast preamplifier and a dedicated software associated to the detection unit, for signals processing. Some results concerning the tritium in relative strong gamma-ray fields are presented.

A system for the automatic measurement and digital display of systolic and diastolic blood pressures

NASA Technical Reports Server (NTRS)

Schulze, A. E.

1971-01-01

Basic components of system are - occluding cuff with mounted cuff microscope, cuff pump deflator, pressure transducer, preamplifier unit, electrocardiograph machine, an analog to digital convertor unit, and digital display unit. System utilizes indirect auscultatory method, based on Korotkoff sounds, for measurement.

The role of defects in Fe(II) – goethite electron transfer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andrade de Notini, Luiza; Latta, Drew; Neumann, Anke

Despite accumulating experimental evidence for Fe(II)-Fe(III) oxide electron transfer, computational chemical calculations suggest that oxidation of sorbed Fe(II) is not energetically feasible unless defects are present. Here we used isotope specific 57Fe Mössbauer spectroscopy to investigate whether Fe(II)-goethite electron transfer is influenced by defects. Specifically, we heated the mineral to try to anneal the goethite surface and ground goethite to try to create defects. We found that heating goethite results in less oxidation of sorbed Fe(II) by goethite. When goethite was re-ground after heating, electron transfer was partially restored. X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) ofmore » heated and ground goethite confirm that heating and grinding alter the surface structure of the goethite. We propose that the heating process annealed the surface and decreased the number of sites where electron transfer could occur. Our experimental findings suggest that surface defects play an important role in Fe(II)-goethite electron transfer as suggested by computational calculations. Our finding that defects influence heterogeneous Fe(II)-goethite electron transfer has important implications for Fe(II) driven recrystallization of Fe oxides, as well as X and Y.« less

Ocean Basin Impact of Ambient Noise on Marine Mammal Detectability, Distribution, and Acoustic Communication - YIP

DTIC Science & Technology

2011-09-30

when applying the 4 passive sonar equation. The integration of acoustic time series from different ocean basins will provide a synoptic...Penn State ARL Hydrophone Analog signal (V) Preamplifiers & 24-bit AiD 1-100 HzBP filter Signal Flow for a Single Hydrophone Digital signal

System Measures Thermal Noise In A Microphone

NASA Technical Reports Server (NTRS)

Zuckerwar, Allan J.; Ngo, Kim Chi T.

1994-01-01

Vacuum provides acoustic isolation from environment. System for measuring thermal noise of microphone and its preamplifier eliminates some sources of error found in older systems. Includes isolation vessel and exterior suspension, acting together, enables measurement of thermal noise under realistic conditions while providing superior vibrational and accoustical isolation. System yields more accurate measurements of thermal noise.

External Peltier Cooler For Low-Noise Amplifier

NASA Technical Reports Server (NTRS)

Soper, Terry A.

1990-01-01

Inexpensive Peltier-effect cooling module made of few commercially available parts used to reduce thermal noise in microwave amplifier. Retrofitted to almost any microwave low-noise amplifier or receiver preamplifier used in communication, telemetry, or radar. Includes copper or aluminum cold plate held tightly against unit to be cooled by strap-type worm-gear clamps.

New type of eddy current sensor for large-displacement test

NASA Astrophysics Data System (ADS)

Pan, Haifeng; Zhu, Huizhong; Fu, Zhibin; Xu, Yuzheng; Feng, Guanping

2001-09-01

In this paper a new type of large displacement eddy current sensor is developed to overcome the three main disadvantages of the traditional eddy current senor. For a traditional sensor, the measurement range is limited and less than one half of the diameter of the measuring coil. The output is high sensitivity to the changes of the target material and the cable length connected between the probe and the preamplifier. When the material or the cable length changed, it is necessary to readjust the preamplifier. The probe of the new eddy current sensor has three coaxial measuring coils, one is an exciting coil and the other two are receiving coils. The diameter of measuring coils is (Phi) 11 mm. The measurement range of this sensor is 40mm and almost four times of the diameter of the coil. The form of differential input and feedback amplification is used in signal amplifier. Thus the effect of the common modules, such as the changes of the target material and the cable length, can be counteracted well.

Gain-switched laser diode seeded Yb-doped fiber amplifier delivering 11-ps pulses at repetition rates up to 40-MHz

NASA Astrophysics Data System (ADS)

Ryser, Manuel; Neff, Martin; Pilz, Soenke; Burn, Andreas; Romano, Valerio

2012-02-01

Here, we demonstrate all-fiber direct amplification of 11 picosecond pulses from a gain-switched laser diode at 1063 nm. The diode was driven at a repetition rate of 40 MHz and delivered 13 μW of fiber-coupled average output power. For the low output pulse energy of 0.33 pJ we have designed a multi-stage core pumped preamplifier based on single clad Yb-doped fibers in order to keep the contribution of undesired amplified spontaneous emission as low as possible and to minimize temporal and spectral broadening. After the preamplifier we reduced the 40 MHz repetition rate to 1 MHz using a fiber coupled pulse-picker. The final amplification was done with a cladding pumped Yb-doped large mode area fiber and a subsequent Yb-doped rod-type fiber. With our setup we achieved amplification of 72 dBs to an output pulse energy of 5.7 μJ, pulse duration of 11 ps and peak power of >0.6 MW.

A preamplification approach to GMO detection in processed foods.

PubMed

Del Gaudio, S; Cirillo, A; Di Bernardo, G; Galderisi, U; Cipollaro, M

2010-03-01

DNA is widely used as a target for GMO analysis because of its stability and high detectability. Real-time PCR is the method routinely used in most analytical laboratories due to its quantitative performance and great sensitivity. Accurate DNA detection and quantification is dependent on the specificity and sensitivity of the amplification protocol as well as on the quality and quantity of the DNA used in the PCR reaction. In order to enhance the sensitivity of real-time PCR and consequently expand the number of analyzable target genes, we applied a preamplification technique to processed foods where DNA can be present in low amounts and/or in degraded forms thereby affecting the reliability of qualitative and quantitative results. The preamplification procedure utilizes a pool of primers targeting genes of interest and is followed by real-time PCR reactions specific for each gene. An improvement of Ct values was found comparing preamplified vs. non-preamplified DNA. The strategy reported in the present study will be also applicable to other fields requiring quantitative DNA testing by real-time PCR.

The design of CMOS general-purpose analog front-end circuit with tunable gain and bandwidth for biopotential signal recording systems.

PubMed

Chen, Wei-Ming; Yang, Wen-Chia; Tsai, Tzung-Yun; Chiueh, Herming; Wu, Chung-Yu

2011-01-01

In this paper an 8-channel CMOS general-purpose analog front-end (AFE) circuit with tunable gain and bandwidth for biopotential signal recording systems is presented. The proposed AFE consists of eight chopper stabilized pre-amplifiers, an 8-to-1 analog multiplexer, and a programmable gain amplifier. It can be used to sense and amplify different kinds of biopotential signals, such as electrocorticogram (ECoG), electrocardiogram (ECG) and electromyogram (EMG). The AFE chip is designed and fabricated in 0.18-μm CMOS technology. The measured maximum gain of AFE is 60.8 dB. The low cutoff frequency can achieve as low as 0.8 Hz and high cutoff frequency can be adjusted from 200 Hz to 10 kHz to suit for different kinds of biopotential signals. The measured input-referred noise is 0.9 μV(rms), with the power consumption of 18μW per channel at 1.8-V power supply. And the noise efficiency factor (NEF) is only 1.3 for pre-amplifier.

Method and apparatus for digitally based high speed x-ray spectrometer for direct coupled use with continuous discharge preamplifiers

DOEpatents

Warburton, W.K.

1998-06-30

A high speed, digitally based, signal processing system is disclosed which accepts directly coupled input data from a detector with a continuous discharge type preamplifier and produces a spectral analysis of the x-rays illuminating the detector. The system`s principal elements are an analog signal conditioning section, a combinatorial logic section which implements digital triangular filtering and pileup inspection, and a microprocessor which accepts values captured by the logic section and uses them to compute x-ray energy values. Operating without pole-zero correction, the system achieves high resolution by capturing, in conjunction with each peak value from the digital filter, an associated value of the unfiltered signal, and using this latter signal to correct the former for errors which arise from its local slope terms. This correction greatly reduces both energy resolution degradation and peak centroid shifting in the output spectrum as a function of input count rate. When the noise of this correction is excessive, a modification allows two filtered averages of the signal to be captured and a corrected peak amplitude computed therefrom. 14 figs.

Method and apparatus for digitally based high speed x-ray spectrometer for direct coupled use with continuous discharge preamplifiers

DOEpatents

Warburton, William K.

1998-01-01

A high speed, digitally based, signal processing system which accepts directly coupled input data from a detector with a continuous discharge type preamplifier and produces a spectral analysis of the x-rays illuminating the detector. The system's principal elements are an analog signal conditioning section, a combinatorial logic section which implements digital triangular filtering and pileup inspection, and a microprocessor which accepts values captured by the logic section and uses them to compute x-ray energy values. Operating without pole-zero correction, the system achieves high resolution by capturing, in conjunction with each peak value from the digital filter, an associated value of the unfiltered signal, and using this latter signal to correct the former for errors which arise from its local slope terms. This correction greatly reduces both energy resolution degradation and peak centroid shifting in the output spectrum as a function of input count rate. When the noise of this correction is excessive, a modification allows two filtered averages of the signal to be captured and a corrected peak amplitude computed therefrom.

Position-sensitive proportional counter with low-resistance metal-wire anode

DOEpatents

Kopp, Manfred K.

1980-01-01

A position-sensitive proportional counter circuit is provided which allows the use of a conventional (low-resistance, metal-wire anode) proportional counter for spatial resolution of an ionizing event along the anode of the counter. A pair of specially designed active-capacitance preamplifiers are used to terminate the anode ends wherein the anode is treated as an RC line. The preamplifiers act as stabilized active capacitance loads and each is composed of a series-feedback, low-noise amplifier, a unity-gain, shunt-feedback amplifier whose output is connected through a feedback capacitor to the series-feedback amplifier input. The stabilized capacitance loading of the anode allows distributed RC-line position encoding and subsequent time difference decoding by sensing the difference in rise times of pulses at the anode ends where the difference is primarily in response to the distributed capacitance along the anode. This allows the use of lower resistance wire anodes for spatial radiation detection which simplifies the counter construction and handling of the anodes, and stabilizes the anode resistivity at high count rates (>10.sup.6 counts/sec).

A Compact Ion and Neutral Mass Spectrometer for Measuring Atmospheric Composition with Preliminary Results from the Dellingr Mission

NASA Astrophysics Data System (ADS)

Jones, S.; Paschalidis, N.; Rodriguez, M.; Sittler, E. C., Jr.; Chornay, D. J.; Uribe, P.; Cameron, T.

2017-12-01

A compact Ion and Neutral Mass Spectrometer (INMS) has been developed for GSFC's Dellingr mission, using the 6U CubeSat platform. Dellingr is expected to deploy into ISS orbit in October 2017 to measure the dynamics of the ionosphere-thermosphere-mesosphere and to determine the steady state background atmospheric conditions at this altitude. The INMS makes in situ measurements of ionized and neutral H, He, N, O, N2, O2 densities with M/dM of approximately 10-12 for thermal particles. The INMS is based on particle acceleration, electronically gated time of flight (TOF), electrostatic analyzer, and CEM detectors. The compact instrument has a dual symmetric configuration with ion and neutral sensor heads on opposite sides of the shared electronics. The neutral front-end includes thermionic ionization and ion-blocking grids. The electronics include fast preamplifiers, electric gating, and TOF measurements and processing, C&DH digital electronics for commands, data storage and back-end I/O, and HVPS for detector and sensor biases. The data package includes 400 bins of mass spectra per ion and neutral sensor and key housekeeping and calibration data, in a single time tagged data frame of 14kbits uncompressed. The nominal data sampling is 1 sec corresponding to 7.5km spatial resolution in LEO orbits. This miniaturized instrument occupies a 1.1U volume, weighs only 570g and nominally operates at 1.2W. This presentation will include preliminary flight data of ions and neutrals from the Dellingr mission and outlines improvements incorporated into the design for the Dellingr (Oct 2017), ExoCube2 (Dec 2017) and petitSat (2020) CubeSat missions.

Development of a Position Decoding ASIC for SPECT using Silicon Photomultiplier

NASA Astrophysics Data System (ADS)

Cho, M.; Kim, H.; Lim, K. T.; Cho, G.

2016-01-01

Single Photon Emission Computed Tomography(SPECT) is a widely used diagnosis modality for detecting metabolic diseases. In general, SPECT system is consisted of a sensor, a pre-amplifier, position decoding circuits(PDC) and a data acquisition(DAQ) system. Due to such complexity, it is quite costly to assemble SPECT system by putting discrete components together. Moreover, using discrete components would make the system rather bulky. In this work, we designed a channel module ASIC for SPECT system. This system was composed of a transimpedance amplifier(TIA), comparators and digital logics. In this particular module, a TIA was selected as a preamplifier because the decay time and the rise time are shorter than that of other preamplifier topologies. In the proposed module, the amplified pulse from the TIA was split into two separate signals and each signal was then fed into two comparators with different reference levels, e.g., a low and high level. Then an XOR gate combined the comparator outputs and the output of XOR gate was sent to the suceeding digital logic. Furthermore, the output of each component in the module is composed of a signal packet. The packet includes the information on the energy, the time and the position of the incident photon. The energy and position information of a detected radiation can be derived from the output of the D-flipflop(DFF) in the module via time-over-threshold(TOT). The timing information was measured using a delayed rising edge from the low-level referenced comparator. There are several advantages in developing the channel module ASIC. First of all, the ASIC has only digital outputs and thus a correction circuit for analog signal distortion can be neglected. In addition, it is possible to cut down the system production cost because the volume of the system can be reduced due to the compactness of ASIC. The benefits of channel module is not only limited to SPECT but also beneficial to many other radiation detecting systems.

X-band preamplifier filter

NASA Technical Reports Server (NTRS)

Manshadi, F.

1986-01-01

A low-loss bandstop filter designed and developed for the Deep Space Network's 34-meter high-efficiency antennas is described. The filter is used for protection of the X-band traveling wave masers from the 20-kW transmitter signal. A combination of empirical and theoretical techniques was employed as well as computer simulation to verify the design before fabrication.

Onboard Acoustic Data-Processing for the Statistical Analysis of Array Beam-Noise,

DTIC Science & Technology

1980-12-15

performance of the sonar system as a measurement tool and others that can assess the character of the ambient- noise field at the time of the measurement. In...the plot as would "dead" hydrophones. A reduction in sensitivity of a hydrophone, a faulty preamplifier , or any other fault in the acoustic channel

Digital frequency domain multiplexing readout electronics for the next generation of millimeter telescopes

NASA Astrophysics Data System (ADS)

Bender, Amy N.; Cliche, Jean-François; de Haan, Tijmen; Dobbs, Matt A.; Gilbert, Adam J.; Montgomery, Joshua; Rowlands, Neil; Smecher, Graeme M.; Smith, Ken; Wilson, Andrew

2014-07-01

Frequency domain multiplexing (fMux) is an established technique for the readout of transition-edge sensor (TES) bolometers in millimeter-wavelength astrophysical instrumentation. In fMux, the signals from multiple detectors are read out on a single pair of wires reducing the total cryogenic thermal loading as well as the cold component complexity and cost of a system. The current digital fMux system, in use by POLARBEAR, EBEX, and the South Pole Telescope, is limited to a multiplexing factor of 16 by the dynamic range of the Superconducting Quantum Interference Device pre-amplifier and the total system bandwidth. Increased multiplexing is key for the next generation of large format TES cameras, such as SPT-3G and POLARBEAR2, which plan to have on the of order 15,000 detectors. Here, we present the next generation fMux readout, focusing on the warm electronics. In this system, the multiplexing factor increases to 64 channels per module (2 wires) while maintaining low noise levels and detector stability. This is achieved by increasing the system bandwidth, reducing the dynamic range requirements though active feedback, and digital synthesis of voltage biases with a novel polyphase filter algorithm. In addition, a version of the new fMux readout includes features such as low power consumption and radiation-hard components making it viable for future space-based millimeter telescopes such as the LiteBIRD satellite.

The Crystal Zero Degree Detector at BESIII

NASA Astrophysics Data System (ADS)

Koch, L.; Denig, A.; Drexler, P.; Garillon, B.; Johansson, T.; Kühn, W.; Lange, S.; Lauth, W.; Liang, Y.; Marciniewski, P.; Rathmann, T.; Redmer, C.

2017-07-01

The BESIII experiment at the BEPCII electron positron collider at IHEP (Beijing) is collecting data in the charm-τ mass region. Electron positron collisions are a very well suited environment for the study of initial state radiation (ISR). However, the photons from ISR are strongly peaked towards small polar angles and are currently detected with limited efficiency. In order to increase the detection efficiency of ISR photons, we are developing small-size calorimeters to be placed in the very forward and backward regions. Each detector will consist of two 4×3 arrays of 1×1×14 cm3 LYSO crystals. A 1 cm gap separating each of the two arrays will reduce the contamination from background at very low angles. The scintillation light will be collected by silicon photomultipliers (SiPMs). The expected event rate in the MHz range requires flash ADCs recording the preamplified SiPM outputs.The digitized waveforms will be analyzed in realtime yielding data reduction and pile-up detection. This high bandwidth data stream will be transmitted via optical fibers to FPGA-based hardware performing sub-event building, buffering, and event correlation with the BESIII trigger. The sub-events with a corresponding trigger will be sent to the BESIII event builder via TCP/IP. A single crystal equipped with a SiPM was instrumented as a prototype detector. Tests with radioactive sources were performed successfully.

Status of the NectarCAM camera project

NASA Astrophysics Data System (ADS)

Glicenstein, J.-F.; Barcelo, M.; Barrio, J.-A.; Blanch, O.; Boix, J.; Bolmont, J.; Boutonnet, C.; Brun, P.; Chabanne, E.; Champion, C.; Colonges, S.; Corona, P.; Courty, B.; Delagnes, E.; Delgado, C.; Diaz, C.; Ernenwein, J.-P.; Fegan, S.; Ferreira, O.; Fesquet, M.; Fontaine, G.; Fouque, N.; Henault, F.; Gascón, D.; Giebels, B.; Herranz, D.; Hermel, R.; Hoffmann, D.; Horan, D.; Houles, J.; Jean, P.; Karkar, S.; Knödlseder, J.; Martinez, G.; Lamanna, G.; LeFlour, T.; Lévêque, A.; Lopez-Coto, R.; Louis, F.; Moudden, Y.; Moulin, E.; Nayman, P.; Nunio, F.; Olive, J.-F.; Panazol, J.-L.; Pavy, S.; Petrucci, P.-O.; Punch, M.; Prast, Julie; Ramon, P.; Rateau, S.; Ribó, M.; Rosier-Lees, S.; Sanuy, A.; Sizun, P.; Sieiro, J.; Sulanke, K.-H.; Tavernet, J.-P.; Tejedor, L. A.; Toussenel, F.; Vasileiadis, G.; Voisin, V.; Waegebert, V.; Zurbach, C.

2014-07-01

NectarCAM is a camera designed for the medium-sized telescopes of the Cherenkov Telescope Array (CTA) covering the central energy range 100 GeV to 30 TeV. It has a modular design based on the NECTAr chip, at the heart of which is a GHz sampling Switched Capacitor Array and 12-bit Analog to Digital converter. The camera will be equipped with 265 7-photomultiplier modules, covering a field of view of 7 to 8 degrees. Each module includes the photomultiplier bases, High Voltage supply, pre-amplifier, trigger, readout and Thernet transceiver. Events recorded last between a few nanoseconds and tens of nanoseconds. A flexible trigger scheme allows to read out very long events. NectarCAM can sustain a data rate of 10 kHz. The camera concept, the design and tests of the various subcomponents and results of thermal and electrical prototypes are presented. The design includes the mechanical structure, the cooling of electronics, read-out, clock distribution, slow control, data-acquisition, trigger, monitoring and services. A 133-pixel prototype with full scale mechanics, cooling, data acquisition and slow control will be built at the end of 2014.

SPE analysis of high efficiency PMTs for the DEAP-3600 dark matter detector

NASA Astrophysics Data System (ADS)

Olsen, Kevin; Hallin, Aksel; DEAP/CLEAN Collaboration

2011-09-01

The Dark matter Experiment using Argon Pulse-shape discrimination is a collaborative effort to develop a next-generation, tonne-scale dark matter detector at SNOLAB. The detector will feature a single-phase liquid argon (LAr) target surrounded by an array of 266 photomultiplier tubes (PMTs). A new high-efficiency Hamamatsu R877-100 PMT has been delivered to the University of Alberta for evaluation by the DEAP collaboration. The increase in efficiency could lead to a much greater light yield, but other experiments have reported a slower rise time [1],[2]. We have placed the PMT in a small dark box and had a base and preamplifier designed to be used with either an oscilloscope or a multi-channel analyzer. With this setup we have demonstrated the PMT's ability to distinguish single photo-electrons (SPE) and characterized the PMT by measuring the SPE pulse height spectrum, the peak-to-valley ratio, the dark pulse rate, the baseline, time resolution and SPE efficiency for varying the high voltage supplied to the PMT.

Flexible, phase-matched, linear receive arrays for high-field MRI in monkeys.

PubMed

Goense, Jozien; Logothetis, Nikos K; Merkle, Hellmut

2010-10-01

High signal-to-noise ratios (SNR) are essential for high-resolution anatomical and functional MRI. Phased arrays are advantageous for this but have the drawback that they often have inflexible and bulky configurations. Particularly in experiments where functional MRI is combined with simultaneous electrophysiology, space constraints can be prohibitive. To this end we developed a highly flexible multiple receive element phased array for use on anesthetized monkeys. The elements are interchangeable and different sizes and combinations of coil elements can be used, for instance, combinations of single and overlapped elements. The preamplifiers including control electronics are detachable and can serve a variety of prefabricated and phase matched arrays of different configurations, allowing the elements to always be placed in close proximity to the area of interest. Optimizing performance of the individual elements ensured high SNR at the cortical surface as well as in deeper laying structures. Performance of a variety of arrangements of gapped linear arrays was evaluated at 4.7 and 7T in high-resolution anatomical and functional MRI. Copyright © 2010 Elsevier Inc. All rights reserved.

Design and fabrication of a new electrolarynx and voice amplifier for laryngectomees.

PubMed

Sundeep Krishna, M; Jayanthy, A K; Divakar, C; Mekhala, R

2005-01-01

A Laryngectomee is a person whose vocal cords i.e. voice box is surgically removed owing to cancer or due to automobile accidents, burns or trauma. The patient, therefore permanently loses the ability to speak normally. An Electrolarynx is an electronic speech aid that enables the Laryngectomee to communicate with other people as quickly as possible after the successful removal of the larynx. A neck type Electrolarynx has been designed. Earlier designs could not alter frequency and intensity simultaneously during conversation. The Electrolarynx developed can control both frequency and intensity simultaneously during conversation. The device has been tested on the patient and found to be very effective. A portable, pocket size, battery powered voice amplifier (PA system) has also been developed which uses an electret condenser microphone as the input. The voice amplifier developed is a two stage amplifier which uses a preamplifier stage and a power amplifier stage. The output of the power amplifier is connected to a speaker. The device is being used by the patient and found to be very useful.

The Vector Electric Field Instrument on the C/NOFS Satellite

NASA Technical Reports Server (NTRS)

Pfaff, R.; Kujawski, J.; Uribe, P.; Bromund, K.; Fourre, R.; Acuna, M.; Le, G.; Farrell, W.; Holzworth, R.; McCarthy, M.;

A noise thermometry investigation of the melting point of gallium at the NIM

NASA Astrophysics Data System (ADS)

Zhang, J. T.; Xue, S.

2006-06-01

This paper describes a study of the melting point of gallium with the new NIM Johnson noise thermometer (JNT). The new thermometer adopts the structure of switching correlator and commutator with the reference resistor maintained at the triple point of water. The electronic system of the new thermometer is basically the same as the current JNT, but the preamplifiers have been improved slightly. This study demonstrates that examining the characteristics of the noise signals in the frequency domain is of critical importance in constructing an improved new thermometer, where a power spectral analysis is found to be critical in establishing appropriate grounding for the new thermometer. The new JNT is tested on measurements of the thermodynamic temperature of the melting point of gallium, which give the thermodynamic temperature of 302.9160 K, with an overall integration time of 190 h and a combined standard uncertainty of 9.4 mK. The uncertainty analysis indicates that a standard combined uncertainty of 3 mK could be achieved with the new thermometer over an integration period of 1750 h.

The data acquisition system of the Latin American Giant Observatory (LAGO)

NASA Astrophysics Data System (ADS)

Sofo Haro, M.; Arnaldi, L. H.; Alvarez, W.; Alvarez, C.; Araujo, C.; Areso, O.; Arnaldi, H.; Asorey, H.; Audelo, M.; Barros, H.; Bertou, X.; Bonnett, M.; Calderon, R.; Calderon, M.; Campos-Fauth, A.; Carramiñana, A.; Carrasco, E.; Carrera, E.; Cazar, D.; Cifuentes, E.; Cogollo, D.; Conde, R.; Cotzomi, J.; Dasso, S.; De Castro, A.; De La Torre, J.; De León, R.; Estupiñan, A.; Galindo, A.; Garcia, L.; Gómez Berisso, M.; González, M.; Guevara, W.; Gulisano, A. M.; Hernández, H.; Jaimes, A.; López, J.; Mantilla, C.; Martín, R.; Martinez-Mendez, A.; Martínez, O.; Martins, E.; Masías-Meza, J. J.; Mayo-García, R.; Melo, T.; Mendoza, J.; Miranda, P.; Montes, E.; Morales, E.; Morales, I.; Moreno, E.; Murrugarra, C.; Nina, C.; Núñez, L. A.; Núñez-Castiñeyra, A.; Otiniano, L.; Peña-Rodríguez, J.; Perenguez, J.; Pérez, H.; Perez, Y.; Perez, G.; Pinilla-Velandia, S.; Ponce, E.; Quishpe, R.; Quispe, F.; Reyes, K.; Rivera, H.; Rodriguez, J.; Rodríguez-Pascual, M.; Romero, M.; Rubio-Montero, A. J.; Salazar, H.; Salinas, J.; Sarmiento-Cano, C.; Sidelnik, I.; Haro, M. Sofo; Suárez-Durán, M.; Subieta, M.; Tello, J.; Ticona, R.; Torres, I.; Torres-Niño, L.; Truyenque, J.; Valencia-Otero, M.; Vargas, S.; Vásquez, N.; Villasenor, L.; Zamalloa, M.; Zavala, L.

2016-06-01

LAGO is an extended cosmic ray observatory composed of water-Cherenkov detectors (WCD) placed throughout Latin America. It is dedicated to the study of various issues related to astrophysics, space weather and atmospheric physics at the regional scale. In this paper we present the design and implementation of the front-end electronics and the data acquisition system for readout of the WCDs of LAGO. The system consists of preamplifiers and a digital board sending data to a computer via an USB interface. The analog signals are acquired from three independent channels at a maximum rate of ~1.2×105 pulses per second and a sampling rate of 40 MHz. To avoid false trigger due to baseline fluctuations, we present in this work a baseline correction algorithm that makes it possible to use WCDs to study variations of the environmental radiation. A data logging software has been designed to format the received data. It also enables an easy access to the data for an off-line analysis, together with the operational conditions and environmental information. The system is currently used at different sites of LAGO.

Mechanisms of electron transfer from structrual Fe(II) in reduced nontronite to oxygen for production of hydroxyl radicals

NASA Astrophysics Data System (ADS)

Yuan, Songhu; Liu, Xixiang; Liao, Wenjuan; Zhang, Peng; Wang, Xiaoming; Tong, Man

2018-02-01

Production of hydroxyl radicals (radOH) has been recently revealed upon oxygenation of sediments in redox-dynamic subsurface environments. In particular, Fe(II)-bearing clay minerals are the major sediment components contributing to radOH production upon oxygenation, and the produced radOH can oxidize contaminants and inactivate bacteria. Whereas, the mechanisms of radOH production from oxygenation of Fe(II)-bearing clay minerals remain elusive. The objectives of this study were to identify the structural variation of Fe(II) entities during the oxidation of Fe(II)-bearing clay minerals by O2, and to unravel the mechanisms of electron transfer within the mineral structure and from mineral to O2 for radOH production. Nontronite (NAu-2, 23% Fe) which was chemically reduced to 54.5% Fe(II) in total Fe was used as a model Fe(II)-bearing clay mineral. Production of radOH and oxidation of Fe(II) were measured during the oxidation of reduced NAu-2 by O2. A wide spectrum of spectroscopic techniques, including Fourier transform infrared spectroscopy (FTIR), Fe K-edge X-ray absorption spectroscopy (XAS), Mössbauer spectra, and X-ray photoelectron spectroscopy (XPS), were employed to explore the structural variation of Fe(II) entities in NAu-2 and the electron transfer within NAu-2 and from NAu-2 to O2. For 180 min oxidation of 1 g/L reduced NAu-2, a biphasic radOH production was observed, being quick within the initial 15 min and slow afterwards. Production of radOH correlates well with oxidation of Fe(II) in the reduced NAu-2. Within the initial 15 min, trioctahedral Fe(II)-Fe(II)-Fe(II) entities and edge Fe(II) in the reduced NAu-2 were preferentially and quickly oxidized, and electrons from the interior Fe(II)-Fe(II)-Fe(II) entities were most likely ejected from the basal siloxane plane to O2. Meanwhile, trioctahedral Fe(II)-Fe(II)-Fe(II) entities were mainly transformed to dioctahedral Fe(II)-Fe(II) entities. When the time of oxygenation was longer than 15 min, dioctahedral Al-Fe(II), Fe(II)-Fe(II) and Fe(II)-Fe(III) entities were slowly oxidized, and the interior electrons were transported through Fe(II)-O-Fe(III) linkages to edges and then ejected to O2. In the slow stage of oxidation, electrons from interior Fe(II) accumulated towards the near surface layers and fueled the regeneration of edge Fe(II) for radOH production. In both stages, one-electron transfer mechanism with the involvement of O2rad - and H2O2 applies for radOH production from the oxidation of structural Fe(II) by O2. The mechanisms unraveled in this study advance the understanding of reactive oxygen species (ROS) production and structural Fe variation when Fe(II)-bearing clay minerals are oxygenated in redox-dynamic systems.

The FIELDS experiment for Solar Probe Plus

NASA Astrophysics Data System (ADS)

Bale, S.; Spp/Fields Team

2010-12-01

Many of our basic ideas on the plasma physics of acceleration, energy flow, and dissipation, and structure of the solar wind have never been rigorously confronted by direct experimental measurements in the region where these processes are actually occurring. Although Alfven waves, shocks, and magnetic reconnection are often invoked as heating mechanisms, there have never been any direct measurements of Alfvenic waves nor the associated Poynting flux nor any measurements of ion or electron kinetic energy flux in the region from 10 R_s to 30 R_s where the final stages of wind acceleration are believed to occur. The radial profiles of both slow and fast solar wind acceleration are based on remote-sensing measurements and have been obtained for only a few selected events. Thus, the spatial radial and perpendicular scales of the acceleration process have been averaged by line-of-sight effects and the possibility of intense localized acceleration cannot be ruled out. The Solar Probe Plus (SPP) mission calls for the high quality fields and particles measurements required to solve the coronal heating and wind acceleration problem. The SPP 'FIELDS' experiment measures the electric and magnetic fields fundamental to the plasma physics of the structured and turbulent solar wind, flux ropes, collisionless shocks, and magnetic reconnection. FIELDS will make the first-ever measurements of the DC/Low-Frequency electric field inside of 1 AU allowing for in situ, high cadence measurements of the Poynting vector, the Elsasser variables, and E/B diagnostics of the wave spectrum to fce in the solar wind. SPP/FIELDS measures the radio wave (type III and II) signatures of microflares, energized electrons, and CME propagation. SPP/ FIELDS measures the plasma electron density to ~2% accuracy and the core electron temperature to ~5-10% accuracy more than 90% of the time at perihelion. FIELDS will also measure the in situ density fluctuation spectrum and structures at a very high cadence (≤ 10 kHz) and provide definitive signatures of the turbulent nature and heating of the solar wind plasma. Furthermore, SPP/FIELDS measures the impact rate and sig- natures of dust from micron- to nano-scales, by measuring the voltage signature of dust impacts on the spacecraft. FIELDS will also measure the floating potential of the SPP spacecraft, which is essential for correcting in situ electron data. The SPP/FIELDS experiment combines four (4) deployable electric antennas, fluxgate and search coil magnetometers and the associated signal processing electronics into a scientifically and technically integrated package. SPP/FIELDS makes very high cadence measurements of fields and density and employs an internal burst memory for intelligent data selection. FIELDS is required to measure very large plasma potentials and electric fields (~10V) and uses floating ground (+/- 100V) power preamplifiers. The SPP/FIELDS team has performed 3D plasma simulations of the SPP spacecraft plasma environ- ment, which reveal enormous voltage fluctuation levels in the plasma wake behind the spacecraft. This voltage noise dominates the true signal by orders of magnitude in the critical DC/LF frequency range. Therefore, we are proposing a design which places the four (4) electric antennas in front of the spacecraft ahead of the heat shield.

Internal electron transfer between hemes and Cu(II) bound at cysteine beta93 promotes methemoglobin reduction by carbon monoxide.

PubMed

Bonaventura, C; Godette, G; Tesh, S; Holm, D E; Bonaventura, J; Crumbliss, A L; Pearce, L L; Peterson, J

1999-02-26

Previous studies showed that CO/H2O oxidation provides electrons to drive the reduction of oxidized hemoglobin (metHb). We report here that Cu(II) addition accelerates the rate of metHb beta chain reduction by CO by a factor of about 1000. A mechanism whereby electron transfer occurs via an internal pathway coupling CO/H2O oxidation to Fe(III) and Cu(II) reduction is suggested by the observation that the copper-induced rate enhancement is inhibited by blocking Cys-beta93 with N-ethylmaleimide. Furthermore, this internal electron-transfer pathway is more readily established at low Cu(II) concentrations in Hb Deer Lodge (beta2His --> Arg) and other species lacking His-beta2 than in Hb A0. This difference is consistent with preferential binding of Cu(II) in Hb A0 to a high affinity site involving His-beta2, which is ineffective in promoting electron exchange between Cu(II) and the beta heme iron. Effective electron transfer is thus affected by Hb type but is not governed by the R left arrow over right arrow T conformational equilibrium. The beta hemes in Cu(II)-metHb are reduced under CO at rates close to those observed for cytochrome c oxidase, where heme and copper are present together in the oxygen-binding site and where internal electron transfer also occurs.

Analysis of Optimum Heterodyne Receivers for Coherent Lidar Applications

NASA Technical Reports Server (NTRS)

Amzajerdian, Farzin

2002-01-01

A full analysis of the combined effects of all the noise sources of optical heterodyne receiver and the interaction between the competing control parameters of the receiver detector and pre-amplifier will be presented. This analysis provides the mean for true optimization of the coherent lidar receiver. The significance of the optimization of heterodyne receiver is shown for 2-micron coherent lidar.

Multi-Layer Tiled Array.

DTIC Science & Technology

1996-12-16

the Invention 13 The present invention relates to planar sonar arrays. More 14 particularly, the invention relates to the arrangement of 15...transducer elements in planar sonar arrays. 16 (2) Description of the Prior Art 17 Conventional planar sonar array designs typically comprise 18 ceramic...signal 5 conditioners ( preamplifiers )/as short as possible. However, this 6 requirement complicates fabrication and provides little space to 7

Smart Acoustic Network Using Combined FSK-PSK, Adaptive Beamforming and Equalization

DTIC Science & Technology

2002-09-30

sonar data transmission from underwater vehicle during mission. The two-year objectives for the high-reliability acoustic network using multiple... sonar laboratory) and used for acoustic networking during underwater vehicle operation. The joint adaptive coherent path beamformer method consists...broadband communications transducer, while the low noise preamplifier conditions received signals for analog to digital conversion. External user

Smart Acoustic Network Using Combined FSK-PSK, Adaptive, Beamforming and Equalization

DTIC Science & Technology

2001-09-30

sonar data transmission from underwater vehicle during mission. The two-year objectives for the high-reliability acoustic network using multiple... sonar laboratory) and used for acoustic networking during underwater vehicle operation. The joint adaptive coherent path beamformer method consists...broadband communications transducer, while the low noise preamplifier conditions received signals for analog to digital conversion. External user

Intermediate Energies for Nuclear Astrophysics and the Development of a Position Sensitive Microstrip Detector System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sobotka, Lee G.; Blackmon, J.; Bertulani, C.

2015-12-30

The chemical elements are made at astrophysical sites through a sequence of nuclear reactions often involving unstable nuclei. The overarching aim of this project is to construct a system that allows for the inverse process of nucleosynthesis (i.e. breakup of heavier nuclei into lighter ones) to be studied in high efficiency. The specific problem to be overcome with this grant is inadequate dynamic range and (triggering) threshold to detect the products of the breakup which include both heavy ions (with large energy and large deposited energy in a detector system) and protons (with little energy and deposited energy.) Early onmore » in the grant we provided both TAMU and RIKEN (the site of the eventual experiments) with working systems based on the existing technology. This technology could be used with either an external preamplifier that was to be designed and fabricated by our RIKEN collaborators or upgraded by replacing the existing chip with one we designed. The RIKEN external preamplifier project never can to completion but our revised chip was designed, fabricated, used in a test experiment and performs as required.« less

Electron transfer and atom exchange between aqueous Fe(II) and structural Fe(III) in clays. Role in U and Hg(II) transformations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scherer, Michelle

2016-08-31

During this project, we investigated Fe electron transfer and atom exchange between aqueous Fe(II) and structural Fe(III) in clay minerals. We used selective chemical extractions, enriched Fe isotope tracer experiments, computational molecular modeling, and Mössbauer spectroscopy. Our findings indicate that structural Fe(III) in clay minerals is reduced by aqueous Fe(II) and that electron transfer occurs when Fe(II) is sorbed to either basal planes and edge OH-groups of clay mineral. Findings from highly enriched isotope experiments suggest that up to 30 % of the Fe atoms in the structure of some clay minerals exhanges with aqueous Fe(II). First principles calculations usingmore » a small polaron hopping approach suggest surprisingly fast electron mobility at room temperature in a nontronite clay mineral and are consistent with temperature dependent Mössbauer data Fast electron mobility suggests that electrons may be able to conduct through the mineral fast enough to enable exchange of Fe between the aqueous phase and clay mineral structure. over the time periods we observed. Our findings suggest that Fe in clay minerals is not as stable as previously thought.« less

Factors that control catalytic two- versus four-electron reduction of dioxygen by copper complexes.

PubMed

Fukuzumi, Shunichi; Tahsini, Laleh; Lee, Yong-Min; Ohkubo, Kei; Nam, Wonwoo; Karlin, Kenneth D

2012-04-25

The selective two-electron reduction of O(2) by one-electron reductants such as decamethylferrocene (Fc*) and octamethylferrocene (Me(8)Fc) is efficiently catalyzed by a binuclear Cu(II) complex [Cu(II)(2)(LO)(OH)](2+) (D1) {LO is a binucleating ligand with copper-bridging phenolate moiety} in the presence of trifluoroacetic acid (HOTF) in acetone. The protonation of the hydroxide group of [Cu(II)(2)(LO)(OH)](2+) with HOTF to produce [Cu(II)(2)(LO)(OTF)](2+) (D1-OTF) makes it possible for this to be reduced by 2 equiv of Fc* via a two-step electron-transfer sequence. Reactions of the fully reduced complex [Cu(I)(2)(LO)](+) (D3) with O(2) in the presence of HOTF led to the low-temperature detection of the absorption spectra due to the peroxo complex [Cu(II)(2)(LO)(OO)] (D) and the protonated hydroperoxo complex [Cu(II)(2)(LO)(OOH)](2+) (D4). No further Fc* reduction of D4 occurs, and it is instead further protonated by HOTF to yield H(2)O(2) accompanied by regeneration of [Cu(II)(2)(LO)(OTF)](2+) (D1-OTF), thus completing the catalytic cycle for the two-electron reduction of O(2) by Fc*. Kinetic studies on the formation of Fc*(+) under catalytic conditions as well as for separate examination of the electron transfer from Fc* to D1-OTF reveal there are two important reaction pathways operating. One is a rate-determining second reduction of D1-OTF, thus electron transfer from Fc* to a mixed-valent intermediate [Cu(II)Cu(I)(LO)](2+) (D2), which leads to [Cu(I)(2)(LO)](+) that is coupled with O(2) binding to produce [Cu(II)(2)(LO)(OO)](+) (D). The other involves direct reaction of O(2) with the mixed-valent compound D2 followed by rapid Fc* reduction of a putative superoxo-dicopper(II) species thus formed, producing D.

Parallel Large-scale Semidefinite Programming for Strong Electron Correlation: Using Correlation and Entanglement in the Design of Efficient Energy-Transfer Mechanisms

DTIC Science & Technology

2014-09-24

which nature uses strong electron correlation for efficient energy transfer, particularly in photosynthesis and bioluminescence, (ii) providing an...strong electron correlation for efficient energy transfer, particularly in photosynthesis and bioluminescence, (ii) providing an innovative paradigm...efficient energy transfer, particularly in photosynthesis and bioluminescence, (ii) providing an innovative paradigm for energy transfer in photovoltaic

ON THE NONTHERMAL κ-DISTRIBUTED ELECTRONS IN PLANETARY NEBULAE AND H ii REGIONS: THE κ INDEX AND ITS CORRELATIONS WITH OTHER NEBULAR PROPERTIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yong; Zhang, Bing; Liu, Xiao-Wei, E-mail: zhangy96@hku.hk

2016-01-20

Recently, a suspicion arose that the free electrons in planetary nebulae (PNs) and H ii regions might have nonthermal energy distributions. In this scenario, a κ index is introduced to characterize the electron energy distributions, with smaller κ values indicating larger deviations from Maxwell–Boltzmann distributions. Assuming that this is the case, we determine the κ values for a sample of PNs and H ii regions by comparing the intensities of [O iii] collisionally excited lines and the hydrogen Balmer jump. We find the average κ indices of PNs and H ii regions to be 27 and 32, respectively. Correlations betweenmore » the resultant κ values and various physical properties of the nebulae are examined to explore the potential origin of nonthermal electrons in photoionized gaseous nebulae. However, no positive result is obtained. Thus, the current analysis does not lend support to the idea that κ-distributed electrons are present in PNs and H ii regions.« less

Proton-coupled electron-transfer reduction of dioxygen catalyzed by a saddle-distorted cobalt phthalocyanine.

PubMed

Honda, Tatsuhiko; Kojima, Takahiko; Fukuzumi, Shunichi

2012-03-07

Proton-coupled electron-transfer reduction of dioxygen (O(2)) to afford hydrogen peroxide (H(2)O(2)) was investigated by using ferrocene derivatives as reductants and saddle-distorted (α-octaphenylphthalocyaninato)cobalt(II) (Co(II)(Ph(8)Pc)) as a catalyst under acidic conditions. The selective two-electron reduction of O(2) by dimethylferrocene (Me(2)Fc) and decamethylferrocene (Me(10)Fc) occurs to yield H(2)O(2) and the corresponding ferrocenium ions (Me(2)Fc(+) and Me(10)Fc(+), respectively). Mechanisms of the catalytic reduction of O(2) are discussed on the basis of detailed kinetics studies on the overall catalytic reactions as well as on each redox reaction in the catalytic cycle. The active species to react with O(2) in the catalytic reaction is switched from Co(II)(Ph(8)Pc) to protonated Co(I)(Ph(8)PcH), depending on the reducing ability of ferrocene derivatives employed. The protonation of Co(II)(Ph(8)Pc) inhibits the direct reduction of O(2); however, the proton-coupled electron transfer from Me(10)Fc to Co(II)(Ph(8)Pc) and the protonated [Co(II)(Ph(8)PcH)](+) occurs to produce Co(I)(Ph(8)PcH) and [Co(I)(Ph(8)PcH(2))](+), respectively, which react immediately with O(2). The rate-determining step is a proton-coupled electron-transfer reduction of O(2) by Co(II)(Ph(8)Pc) in the Co(II)(Ph(8)Pc)-catalyzed cycle with Me(2)Fc, whereas it is changed to the electron-transfer reduction of [Co(II)(Ph(8)PcH)](+) by Me(10)Fc in the Co(I)(Ph(8)PcH)-catalyzed cycle with Me(10)Fc. A single crystal of monoprotonated [Co(III)(Ph(8)Pc)](+), [Co(III)Cl(2)(Ph(8)PcH)], produced by the proton-coupled electron-transfer reduction of O(2) by Co(II)(Ph(8)Pc) with HCl, was obtained, and the crystal structure was determined in comparison with that of Co(II)(Ph(8)Pc). © 2012 American Chemical Society

Detection of Humans and Light Vehicles Using Acoustic-to-Seismic Coupling

DTIC Science & Technology

2009-08-31

microphones, video cameras (regular and infrared), magnetic sensors, and active Doppler radar and sonar systems. These sensors could be located at... sonar systems due to dramatic absorption/reflection of electromagnetic/ultrasonic waves [8,9]. 6...engine was turned off, and the car continued moving. This eliminated the engine sound. A PCB microphone, 377B41, with preamplifier , 426A30, and with

A dc amplifier for nuclear particle measurement

NASA Technical Reports Server (NTRS)

Macnee, A. B.; Masnari, N. A.

1978-01-01

A monolithic preamplifier-postamplifier combination has been developed for use with solid state particle detectors. The direct coupled amplifiers employ interdigitated n-channel JFET's, diodes, and diffused resistors. The circuits developed demonstrate the feasibility of matching the performance of existing discrete component designs. The fabrication procedures for the monolithic amplifier fabrication are presented and the results of measurements on a limited number of sample amplifiers are given.

Technology forecasting for space communication. [analysis of systems for application to Spacecraft Data and Tracking Network

NASA Technical Reports Server (NTRS)

1973-01-01

A study was conducted to determine techniques for application to space communication. The subjects considered are as follows: (1) optical communication systems, (2) laser communications for data acquisition networks, (3) spacecraft data rate requirements, (4) telemetry, command, and data handling, (5) spacecraft tracking and data network antenna and preamplifier cost tradeoff study, and (6) spacecraft communication terminal evaluation.

High responsivity coherent photonic receiver integrating an SOA, a 90° hybrid, and high speed UTC photodiodes.

PubMed

Santini, Guillaume; Caillaud, Christophe; Paret, Jean-François; Pommereau, Frederic; Mekhazni, Karim; Calo, Cosimo; Achouche, Mohand

2017-10-16

We demonstrate a single polarization monolithically integrated coherent receiver on an InP substrate with a SOA preamplifier, a 90° optical hybrid, and four 40 GHz UTC photodiodes. Record performances with responsivity above 4 A/W with low imbalance <1 dB and error free detection of 32 Gbaud QPSK signals were simultaneously demonstrated.

Type II flavohemoglobin of Mycobacterium smegmatis oxidizes d-lactate and mediate electron transfer.

PubMed

Thakur, Naveen; Kumar, Ashwani; Dikshit, Kanak L

2018-06-01

Two distantly related flavohemoglobins (FHbs), MsFHbI and MsFHbII, having crucial differences in their heme and reductase domains, co-exist in Mycobacterium smegmatis. Function of MsFHbI is associated with nitric-oxide detoxification but physiological relevance of MsFHbII remains unknown. This study unravels some unique spectral and functional characteristics of MsFHbII. Unlike conventional type I FHbs, MsFHbII lacks nitric-oxide dioxygenase and NADH oxidase activities but utilizes d-lactate as an electron donor to mediate electron transfer. MsFHbII carries a d-lactate dehydrogenase type FAD binding motif in its reductase domain and oxidizes d-lactate in a FAD dependent manner to reduce the heme iron, suggesting that the globin is acting as an electron acceptor. Importantly, expression of MsFHbII in Escherichia coli imparted protection under oxidative stress, suggesting its important role in stress management of its host. Since M. smegmatis lacks the gene encoding for d-lactate dehydrogenase and d-lactate is produced during aerobic metabolism and also as a by-product of lipid peroxidation, the ability of MsFHbII to metabolize d-lactate may provide it a unique ability to balance the oxidative stress generated due to accumulation of d-lactate in the cell and at the same time sequester electrons and pass it to the respiratory apparatus. Copyright © 2018 Elsevier B.V. All rights reserved.

The experimental set-up of the RIB in-flight facility EXOTIC

NASA Astrophysics Data System (ADS)

Pierroutsakou, D.; Boiano, A.; Boiano, C.; Di Meo, P.; La Commara, M.; Manea, C.; Mazzocco, M.; Nicoletto, M.; Parascandolo, C.; Signorini, C.; Soramel, F.; Strano, E.; Toniolo, N.; Torresi, D.; Tortone, G.; Anastasio, A.; Bettini, M.; Cassese, C.; Castellani, L.; Corti, D.; Costa, L.; De Fazio, B.; Galet, G.; Glodariu, T.; Grebosz, J.; Guglielmetti, A.; Molini, P.; Pontoriere, G.; Rocco, R.; Romoli, M.; Roscilli, L.; Sandoli, M.; Stroe, L.; Tessaro, M.; Zatti, P. G.

2016-10-01

We describe the experimental set-up of the Radioactive Ion Beam (RIB) in-flight facility EXOTIC consisting of: (a) two position-sensitive Parallel Plate Avalanche Counters (PPACs), dedicated to the event-by-event tracking of the produced RIBs and to time of flight measurements and (b) the new high-granularity compact telescope array EXPADES (EXotic PArticle DEtection System), designed for nuclear physics and nuclear astrophysics experiments employing low-energy light RIBs. EXPADES consists of eight ΔE -Eres telescopes arranged in a cylindrical configuration around the target. Each telescope is made up of two Double Sided Silicon Strip Detectors (DSSSDs) with a thickness of 40/60 μm and 300 μm for the ΔE and Eres layer, respectively. Additionally, eight ionization chambers were constructed to be used as an alternative ΔE stage or, in conjunction with the entire DSSSD array, to build up more complex triple telescopes. New low-noise multi-channel charge-sensitive preamplifiers and spectroscopy amplifiers, associated with constant fraction discriminators, peak-and-hold and Time to Amplitude Converter circuits were developed for the electronic readout of the ΔE stage. Application Specific Integrated Circuit-based electronics was employed for the treatment of the Eres signals. An 8-channel, 12-bit multi-sampling 50 MHz Analog to Digital Converter, a Trigger Supervisor Board for handling the trigger signals of the whole experimental set-up and an ad hoc data acquisition system were also developed. The performance of the PPACs, EXPADES and of the associated electronics was obtained offline with standard α calibration sources and in-beam by measuring the scattering process for the systems 17O+58Ni and 17O+208Pb at incident energies around their respective Coulomb barriers and, successively, during the first experimental runs with the RIBs of the EXOTIC facility.

Fluorescent probe based subcellular distribution of Cu(II) ions in living electrotrophs isolated from Cu(II)-reduced biocathodes of microbial fuel cells.

PubMed

Tao, Ye; Xue, Hua; Huang, Liping; Zhou, Peng; Yang, Wei; Quan, Xie; Yuan, Jinxiu

2017-02-01

Based on the four indigenous electrotrophs (Stenotrophomonas maltophilia JY1, Citrobacter sp. JY3, Pseudomonas aeruginosa JY5 and Stenotrophomonas sp. JY6) isolated from well adapted Cu(II)-reduced biocathodes of microbial fuel cells (MFCs), a rhodamine based Cu(II) fluorescent probe was used to imaginably and quantitatively track subcellular Cu(II) ions in these electrotrophs. Cathodic electrons led to more Cu(II) ions (14.3-30.1%) in the intracellular sites at operation time of 2-3h with Cu(II) removal rates of 2.90-3.64mg/Lh whereas the absence of cathodic electrons prolonged the appearance of more Cu(II) ions (16.6-22.5%) to 5h with Cu(II) removal rates of 1.96-2.28mg/Lh. This study illustrates that cathodic electrons directed more Cu(II) ions for quicker entrance into the electrotrophic cytoplasm, and gives an alternative approach for developing imaging and functionally tracking Cu(II) ions in the electrotrophs of MFCs. Copyright © 2016 Elsevier Ltd. All rights reserved.

5-Arylvinyl-2,2′-bipyridyls: Bright “push–pull” dyes as components in fluorescent indicators for zinc ions

PubMed Central

Zhu, Lei; Younes, Ali H.; Yuan, Zhao; Clark, Ronald J.

2015-01-01

This article reviews the zinc(II)-dependent photophysical properties of arylvinylbipyridines (AVBs), a class of fluoroionophores in which 2,2′-bipyridyl and an aryl moiety are electronically conjugated. Zinc(II) binding of an AVB may lead to an emission bathochromic shift of the fluoroionophore without diminishing its fluorescence quantum yield. This observation can be explained using the excited state model of electron donor–π bridge–electron acceptor “push–pull” fluorophores, in which the bipy moiety acts as an electron acceptor, and zinc(II)-coordination strengthens its electron affinity. The spectral sensitivity of bipy-containing fluoroionophores, such as AVBs, to zinc(II) can be exploited to prepare fluorescent indicators for this ion. In several cases, AVB moieties are incorporated in fluorescent heteroditopic ligands, so that the variation of zinc(II) concentration over a relatively large range can be correlated to fluorescence changes in either intensity or color. AVB fluoroionophores are also used to introduce an intramolecular Förster resonance energy transfer (FRET) strategy for creating zinc(II) indicators with high photostability and a narrow emission band, two desired characteristics of dyes used in fluorescence microscopy. PMID:26190906

Central Drift Chamber for Belle-II

NASA Astrophysics Data System (ADS)

Taniguchi, N.

2017-06-01

The Central Drift Chamber (CDC) is the main device for tracking and identification of charged particles for Belle-II experiment. The Belle-II CDC is cylindrical wire chamber with 14336 sense wires, 2.3 m-length and 2.2 m-diameter. The wire chamber and readout electronics have been completely replaced from the Belle CDC. The new readout electronics system must handle higher trigger rate of 30 kHz with less dead time at the design luminosity of 8 × 1035 cm-2s-1. The front-end electronics are located close to detector and send digitized signal through optical fibers. The Amp-Shaper-Discriminator chips, FADC and FPGA are assembled on a single board. Belle-II CDC with readout electronics has been installed successfully in Belle structure in October 2016. We will present overview of the Belle-II CDC and status of commissioning with cosmic ray.

The design of high dynamic range ROIC for IRFPAs

NASA Astrophysics Data System (ADS)

Jiang, Dazhao; Liang, Qinghua; Zhang, Qiwen; Chen, Honglei; Ding, Ruijun

2015-10-01

The charge packet readout integrated circuit (ROIC) technology for the IRFPAs is introduced, which can realize that every pixel achieves a very high capacity of the electrons storage, and it also improves the performance of the SNR and reduces the saturation possibility of the pixels. The ROIC for the LWIR requires ability that obtaining high capacity for storing electrons. For the conventional ROIC, the maximum charge capacity is determined by the integration capacitance and the operating voltage, it can achieve a high charge capacity through increasing the area of the integration capacitor or raising the operating voltage. And this paper would introduce a digital method of ROIC that can achieve a very high charge capacity. The circuit architecture of this approach includes the following parts, a preamplifier, a comparator, a counter, and memory arrays. And the maximum charge capacity of the pixel is determined by the counter bits. This new method can achieve a high charge capacity more than 1Ge- every pixel and output the digital signal directly, while that of conventional ROIC is less than 50Me- and output the analog signal from the pixel. In this new circuit, the comparator is a important module, as the integration voltage value need compare with threshold voltage through the comparator all the time during the integration period, and we will discuss the influence of the comparator. This work design the circuit with the CSMC 0.35um CMOS technology, and the simulation use the spectre model.

Electronic still camera

NASA Astrophysics Data System (ADS)

Holland, S. Douglas

1992-09-01

A handheld, programmable, digital camera is disclosed that supports a variety of sensors and has program control over the system components to provide versatility. The camera uses a high performance design which produces near film quality images from an electronic system. The optical system of the camera incorporates a conventional camera body that was slightly modified, thus permitting the use of conventional camera accessories, such as telephoto lenses, wide-angle lenses, auto-focusing circuitry, auto-exposure circuitry, flash units, and the like. An image sensor, such as a charge coupled device ('CCD') collects the photons that pass through the camera aperture when the shutter is opened, and produces an analog electrical signal indicative of the image. The analog image signal is read out of the CCD and is processed by preamplifier circuitry, a correlated double sampler, and a sample and hold circuit before it is converted to a digital signal. The analog-to-digital converter has an accuracy of eight bits to insure accuracy during the conversion. Two types of data ports are included for two different data transfer needs. One data port comprises a general purpose industrial standard port and the other a high speed/high performance application specific port. The system uses removable hard disks as its permanent storage media. The hard disk receives the digital image signal from the memory buffer and correlates the image signal with other sensed parameters, such as longitudinal or other information. When the storage capacity of the hard disk has been filled, the disk can be replaced with a new disk.

Electronic Still Camera

NASA Technical Reports Server (NTRS)

Holland, S. Douglas (Inventor)

1992-01-01

A handheld, programmable, digital camera is disclosed that supports a variety of sensors and has program control over the system components to provide versatility. The camera uses a high performance design which produces near film quality images from an electronic system. The optical system of the camera incorporates a conventional camera body that was slightly modified, thus permitting the use of conventional camera accessories, such as telephoto lenses, wide-angle lenses, auto-focusing circuitry, auto-exposure circuitry, flash units, and the like. An image sensor, such as a charge coupled device ('CCD') collects the photons that pass through the camera aperture when the shutter is opened, and produces an analog electrical signal indicative of the image. The analog image signal is read out of the CCD and is processed by preamplifier circuitry, a correlated double sampler, and a sample and hold circuit before it is converted to a digital signal. The analog-to-digital converter has an accuracy of eight bits to insure accuracy during the conversion. Two types of data ports are included for two different data transfer needs. One data port comprises a general purpose industrial standard port and the other a high speed/high performance application specific port. The system uses removable hard disks as its permanent storage media. The hard disk receives the digital image signal from the memory buffer and correlates the image signal with other sensed parameters, such as longitudinal or other information. When the storage capacity of the hard disk has been filled, the disk can be replaced with a new disk.

Paramagnetic resonance studies of bistrispyrazolylborate cobalt(II) and related derivatives

NASA Astrophysics Data System (ADS)

Myers, William K.

Herein, a systematic frozen solution electron-nuclear double resonance (ENDOR) study of high-spin Co(II) complexes is reported to demonstrate the efficacy of methyl substitutions as a means of separating dipolar and contact coupling, and further, to increase the utility of high-spin Co(II) as a spectroscopic probe for the ubiquitous, but spectroscopically-silent Zn(II) metalloenzymes. High-spin (hs) Co(II) has been subject of paramagnetic resonance studies for over 50 years and has been used as a spectroscopic probe for Zn metalloenzymes for over 35 years. However, as will be seen, the inherent complexity of the electronic properties of the cobaltous ion remains to be exploited to offer a wealth of information on Zn(II) enzymatic environments. Specifically, ENDOR measurements on bistrispyrazolylborate cobalt(II) confirm the utility of the novel method of methyl substitution to differentiate dipolar and Fermi contact couplings. An extensive set of electron paramagnetic resonance (EPR) simulations were performed. Software was developed to implement an ENDOR control interface. Finally, proton relaxation measurements were made in the range of 12-42 MHz, which were accounted for with the large g-value anisotropy of the Co(II) compounds. Taken as a whole, these studies point to the rich complexity of the electronic structure of high-spin cobalt(II) and, when sufficiently well-characterized, the great utility it has as a surrogate of biological Zn(II).

Influence of central metalloligand geometry on electronic communication between metals: syntheses, crystal structures, MMCT properties of isomeric cyanido-bridged Fe2Ru complexes, and TDDFT calculations.

PubMed

Ma, Xiao; Lin, Chen-Sheng; Hu, Sheng-Min; Tan, Chun-Hong; Wen, Yue-Hong; Sheng, Tian-Lu; Wu, Xin-Tao

2014-06-02

To investigate how the central metalloligand geometry influences distant or vicinal metal-to-metal charge-transfer (MMCT) properties of polynuclear complexes, cis- and trans-isomeric heterotrimetallic complexes, and their one- and two-electron oxidation products, cis/trans-[Cp(dppe)Fe(II)NCRu(II)(phen)2CN-Fe(II)(dppe)Cp][PF6]2 (cis/trans-1[PF6]2), cis/trans-[Cp(dppe)Fe(II)NCRu(II)(phen)2CNFe(III)-(dppe)Cp][PF6]3 (cis/trans-1[PF6]3) and cis/trans-[Cp(dppe)Fe(III)NCRu(II)(phen)2CN-Fe(III)(dppe)Cp][PF6]4 (cis/trans-1[PF6]4) have been synthesized and characterized. Electrochemical measurements show the presence of electronic interactions between the two external Fe(II) atoms of the cis- and trans-isomeric complexes cis/trans-1[PF6]2. The electronic properties of all these complexes were studied and compared by spectroscopic techniques and TDDFT//DFT calculations. As expected, both mixed valence complexes cis/trans-1[PF6]3 exhibited different strong absorption signals in the NIR region, which should mainly be attributed to a transition from an MO that is delocalized over the Ru(II)-CN-Fe(II) subunit to a Fe(III) d orbital with some contributions from the co-ligands. Moreover, the NIR transition energy in trans-1[PF6]3 is lower than that in cis-1[PF6]3, which is related to the symmetry of their molecular orbitals on the basis of the molecular orbital analysis. Also, the electronic spectra of the two-electron oxidized complexes show that trans-1[PF6]4 possesses lower vicinal Ru(II) → Fe(III) MMCT transition energy than cis-1[PF6]4. Moreover, the assignment of MMCT transition of the oxidized products and the differences of the electronic properties between the cis and trans complexes can be well rationalized using TDDFT//DFT calculations. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

THE POSSIBLE ROLE OF CORONAL STREAMERS AS MAGNETICALLY CLOSED STRUCTURES IN SHOCK-INDUCED ENERGETIC ELECTRONS AND METRIC TYPE II RADIO BURSTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kong, Xiangliang; Chen, Yao; Feng, Shiwei

2015-01-10

Two solar type II radio bursts, separated by ∼24 hr in time, are examined together. Both events are associated with coronal mass ejections (CMEs) erupting from the same active region (NOAA 11176) beneath a well-observed helmet streamer. We find that the type II emissions in both events ended once the CME/shock fronts passed the white-light streamer tip, which is presumably the magnetic cusp of the streamer. This leads us to conjecture that the closed magnetic arcades of the streamer may play a role in electron acceleration and type II excitation at coronal shocks. To examine such a conjecture, we conduct a test-particle simulationmore » for electron dynamics within a large-scale partially closed streamer magnetic configuration swept by a coronal shock. We find that the closed field lines play the role of an electron trap via which the electrons are sent back to the shock front multiple times and therefore accelerated to high energies by the shock. Electrons with an initial energy of 300 eV can be accelerated to tens of keV concentrating at the loop apex close to the shock front with a counter-streaming distribution at most locations. These electrons are energetic enough to excite Langmuir waves and radio bursts. Considering the fact that most solar eruptions originate from closed field regions, we suggest that the scenario may be important for the generation of more metric type IIs. This study also provides an explanation of the general ending frequencies of metric type IIs at or above 20-30 MHz and the disconnection issue between metric and interplanetary type IIs.« less

Focused electron beam induced deposition of pure SIO II

NASA Astrophysics Data System (ADS)

Perentes, Alexandre; Hoffmann, Patrik; Munnik, Frans

2007-02-01

Focused electron beam induced processing (FEBID) equipments are the "all in one" tools for high resolution investigation, and modification of nano-devices. Focused electron beam induced deposition from a gaseous precursor usually results in a nano-composite sub-structured material, in which the interesting material is embedded in an amorphous carbonaceous matrix. Using the Hydrogen free tetraisocyanatosilane Si(NCO) 4 molecule as Si source, we show how a controlled oxygen flux, simultaneously injected with the precursor vapors, causes contaminants to vanish from the FEB deposits obtained and leads to the deposition of pure SiO II. The chemical composition of the FEBID material could be controlled from SiC IINO 3 to SiO II, the latter containing undetectable foreign element contamination. The [O II] / [TICS] ratio needed to obtain SiO II in our FEB deposition equipment is larger than 300. The evolution of the FEBID material chemical composition is presented as function of the [O II] / [TICS] molecular flux ratios. A hypothetical decomposition pathway of this silane under these conditions is discussed based on the different species formed under electron bombardment of TICS. Transmission electron microscopy investigations demonstrated that the deposited oxide is smooth (roughness sub 2nm) and amorphous. Infrared spectroscopy confirmed the low concentration of hydroxyl groups. The Hydrogen content of the deposited oxide, measured by elastic recoil detection analysis, is as low as 1 at%. 193nm wavelength AIMS investigations of 125nm thick SiO II pads (obtained with [O II] / [TICS] = 325) showed an undetectable light absorption.

Interfacial charge separation and recombination in InP and quasi-type II InP/CdS core/shell quantum dot-molecular acceptor complexes.

PubMed

Wu, Kaifeng; Song, Nianhui; Liu, Zheng; Zhu, Haiming; Rodríguez-Córdoba, William; Lian, Tianquan

2013-08-15

Recent studies of group II-VI colloidal semiconductor heterostuctures, such as CdSe/CdS core/shell quantum dots (QDs) or dot-in-rod nanorods, show that type II and quasi-type II band alignment can facilitate electron transfer and slow down charge recombination in QD-molecular electron acceptor complexes. To explore the general applicability of this wave function engineering approach for controlling charge transfer properties, we investigate exciton relaxation and dissociation dynamics in InP (a group III-V semiconductor) and InP/CdS core/shell (a heterostructure beween group III-V and II-VI semiconductors) QDs by transient absorption spectroscopy. We show that InP/CdS QDs exhibit a quasi-type II band alignment with the 1S electron delocalized throughout the core and shell and the 1S hole confined in the InP core. In InP-methylviologen (MV(2+)) complexes, excitons in the QD can be dissociated by ultrafast electron transfer to MV(2+) from the 1S electron level (with an average time constant of 11.4 ps) as well as 1P and higher electron levels (with a time constant of 0.39 ps), which is followed by charge recombination to regenerate the complex in its ground state (with an average time constant of 47.1 ns). In comparison, InP/CdS-MV(2+) complexes show similar ultrafast charge separation and 5-fold slower charge recombination rates, consistent with the quasi-type II band alignment in these heterostructures. This result demonstrates that wave function engineering in nanoheterostructures of group III-V and II-VI semiconductors provides a promising approach for optimizing their light harvesting and charge separation for solar energy conversion applications.

Multifrequency Pulsed EPR Studies of Biologically Relevant Manganese(II) Complexes

PubMed Central

Stich, T. A.; Lahiri, S.; Yeagle, G.; Dicus, M.; Brynda, M.; Gunn, A.; Aznar, C.; DeRose, V. J.; Britt, R. D.

2011-01-01

Electron paramagnetic resonance studies at multiple frequencies (MF EPR) can provide detailed electronic structure descriptions of unpaired electrons in organic radicals, inorganic complexes, and metalloenzymes. Analysis of these properties aids in the assignment of the chemical environment surrounding the paramagnet and provides mechanistic insight into the chemical reactions in which these systems take part. Herein, we present results from pulsed EPR studies performed at three different frequencies (9, 31, and 130 GHz) on [Mn(II)(H2O)6]2+, Mn(II) adducts with the nucleotides ATP and GMP, and the Mn(II)-bound form of the hammerhead ribozyme (MnHH). Through line shape analysis and interpretation of the zero-field splitting values derived from successful simulations of the corresponding continuous-wave and field-swept echo-detected spectra, these data are used to exemplify the ability of the MF EPR approach in distinguishing the nature of the first ligand sphere. A survey of recent results from pulsed EPR, as well as pulsed electron-nuclear double resonance and electron spin echo envelope modulation spectroscopic studies applied to Mn(II)-dependent systems, is also presented. PMID:22190766

Ballistic Missile Defense Glossary Version 3.0.

DTIC Science & Technology

1997-06-01

The suppression of background noise for the improvement of an object signal. Battlefield Area Evaluation (USA term). Best and Final Offer...field of the lens are focused. An FPA is a matrix of photon sensitive detectors which, when combined with low noise preamplifiers, provides image data...orbital planes with an orbit period of 12 hours at 10,900 nautical miles altitude. Each satellite transmits three L-band, pseudo-random noise -coded

A multichannel EEG telemetry system utilizing a PCM subcarrier

NASA Technical Reports Server (NTRS)

Fryer, T. B.

1974-01-01

A multichannel personal-type telemetry system is described that utilizes PCM encoding for the most effective range with minimum RF bandwidth and noise interference. Recent IC developments (COS MOS) make it possible to implement a sophisticated encoding system (PCM) within the low power and size constraints necessary for a personal biotelemetry system. This system includes low-level high-impedance preamplifiers to make the system suitable for EEG recording.

Microprocessor-based cardiotachometer

NASA Technical Reports Server (NTRS)

Crosier, W. G.; Donaldson, J. A.

1981-01-01

Instrument operates reliably even with stress-test electrocardiogram (ECG) signals subject to noise, baseline wandering, and amplitude change. It records heart rate from preamplified, single-lead ECG input signal and produces digital and analog heart-rate outputs which are fed elsewhere. Analog hardware processes ECG input signal, producing 10-ms pulse for each heartbeat. Microprocessor analyzes resulting pulse train, identifying irregular heartbeats and maintaining stable output during lead switching. Easily modified computer program provides analysis.

Neutron flux measurements using scintillator-photodiode-preamplifier system and new types of scintillators

NASA Astrophysics Data System (ADS)

Ryzhikov, Vladimir D.; Burachas, S. F.; Volkov, V. G.; Danshin, Evgeniy A.; Lisetskaya, Elena K.; Piven, L. A.; Svishch, Vladimir M.; Chernikov, Vyacheslav V.; Filimonov, A. E.

1997-02-01

After the Chernobyl catastrophe among the problems of current concern a question arose of detection of 'hot' particles formed from plutonium alloys with carbon, nitrogen, silicon, etc. For this purpose, the instruments are needed, which would be able to detect not only alpha- particles and low energy gamma-radiation, but also neutrons and high energy gamma-quanta from ((alpha) , n(gamma) ) - reactions. At present for each kind of radiation detectors of different types are used. A general drawback of all these instruments is their narrow dynamic range of dose rates and energies, and especially impossibility to registrate n-flux in condition large background activity gamma-rays nuclei, which makes each of them applicable only under certain specific conditions. For detection of 'hot' particles, oxide and semiconductor scintillators were used, which contained elements with large capture cross section for thermal neutrons. In this paper we try to determine possibilities and limitations of solid-state neutron detectors based on CdS(Te), ZnSe(Te), CdWO4 (CWO), Gd2SiO5 (GSO) scintillators developed and produced by the Science and Technology Center for Radiation Instruments of the Institute for Single Crystals. The instruments developed by Center are based preferable on a very promising system 'scintillator- photodiode-preamplifier' matched with modern computer data processing techniques.

Electronic properties of electron and hole in type-II semiconductor nano-heterostructures

NASA Astrophysics Data System (ADS)

Rahul, K. Suseel; Souparnika, C.; Salini, K.; Mathew, Vincent

2016-05-01

In this project, we record the orbitals of electron and hole in type-II (CdTe/CdSe/CdTe/CdSe) semiconductor nanocrystal using effective mass approximation. In type-II the band edges of both valance and conduction band are higher than that of shell. So the electron and hole get confined in different layers of the hetero-structure. The energy eigen values and eigen functions are calculated by solving Schrodinger equation using finite difference matrix method. Based on this we investigate the effect of shell thickness and well width on energy and probability distribution of ground state (1s) and few excited states (1p,1d,etc). Our results predict that, type-II quantum dots have significant importance in photovoltaic applications.

Formation of tyrosine radicals in photosystem II under far-red illumination.

PubMed

Ahmadova, Nigar; Mamedov, Fikret

2018-04-01

Photosystem II (PS II) contains two redox-active tyrosine residues on the donor side at symmetrical positions to the primary donor, P 680 . Tyr Z , part of the water-oxidizing complex, is a preferential fast electron donor while Tyr D is a slow auxiliary donor to P 680 + . We used PS II membranes from spinach which were depleted of the water oxidation complex (Mn-depleted PS II) to study electron donation from both tyrosines by time-resolved EPR spectroscopy under visible and far-red continuous light and laser flash illumination. Our results show that under both illumination regimes, oxidation of Tyr D occurs via equilibrium with Tyr Z • at pH 4.7 and 6.3. At pH 8.5 direct Tyr D oxidation by P 680 + occurs in the majority of the PS II centers. Under continuous far-red light illumination these reactions were less effective but still possible. Different photochemical steps were considered to explain the far-red light-induced electron donation from tyrosines and localization of the primary electron hole (P 680 + ) on the Chl D1 in Mn-depleted PS II after the far-red light-induced charge separation at room temperature is suggested.

The stability of TlBr detectors at low temperature

NASA Astrophysics Data System (ADS)

Dönmez, Burçin; He, Zhong; Kim, Hadong; Cirignano, Leonard J.; Shah, Kanai S.

2010-11-01

Thallium bromide (TlBr) is a promising semiconductor detector material due to its high atomic number (Tl: 81, Br: 35), high density (7.56 g/cm 3) and wide band gap (2.68 eV). Current TlBr detectors suffer from polarization, which causes performance degradation over time when high voltage is applied. A 4.6-mm thick TlBr detector with pixellated anodes made by Radiation Monitoring Devices Inc. was used in the experiments. The detector has a planar cathode and nine anode pixels surrounded by a guard ring. The pixel pitch is 1.0-mm. Digital pulse waveforms of preamplifier outputs were recorded using a multi-channel GaGe PCI digitizer board for pulse shaping. Several experiments were carried out at -20 °C while the detector was under bias for over a month. No polarization effect was observed and the detector's spectroscopic performance improved over time. Energy resolution of 1.5% FWHM at 662 keV has been measured without depth correction at -2000 V cathode bias. Average electron mobility-lifetime of (5.7±0.8) ×10 -3 cm 2/V has been measured from four anode pixels.

Multi-band infrared camera systems

NASA Astrophysics Data System (ADS)

Davis, Tim; Lang, Frank; Sinneger, Joe; Stabile, Paul; Tower, John

1994-12-01

The program resulted in an IR camera system that utilizes a unique MOS addressable focal plane array (FPA) with full TV resolution, electronic control capability, and windowing capability. Two systems were delivered, each with two different camera heads: a Stirling-cooled 3-5 micron band head and a liquid nitrogen-cooled, filter-wheel-based, 1.5-5 micron band head. Signal processing features include averaging up to 16 frames, flexible compensation modes, gain and offset control, and real-time dither. The primary digital interface is a Hewlett-Packard standard GPID (IEEE-488) port that is used to upload and download data. The FPA employs an X-Y addressed PtSi photodiode array, CMOS horizontal and vertical scan registers, horizontal signal line (HSL) buffers followed by a high-gain preamplifier and a depletion NMOS output amplifier. The 640 x 480 MOS X-Y addressed FPA has a high degree of flexibility in operational modes. By changing the digital data pattern applied to the vertical scan register, the FPA can be operated in either an interlaced or noninterlaced format. The thermal sensitivity performance of the second system's Stirling-cooled head was the best of the systems produced.

Frequency multiplexed superconducting quantum interference device readout of large bolometer arrays for cosmic microwave background measurements.

PubMed

Dobbs, M A; Lueker, M; Aird, K A; Bender, A N; Benson, B A; Bleem, L E; Carlstrom, J E; Chang, C L; Cho, H-M; Clarke, J; Crawford, T M; Crites, A T; Flanigan, D I; de Haan, T; George, E M; Halverson, N W; Holzapfel, W L; Hrubes, J D; Johnson, B R; Joseph, J; Keisler, R; Kennedy, J; Kermish, Z; Lanting, T M; Lee, A T; Leitch, E M; Luong-Van, D; McMahon, J J; Mehl, J; Meyer, S S; Montroy, T E; Padin, S; Plagge, T; Pryke, C; Richards, P L; Ruhl, J E; Schaffer, K K; Schwan, D; Shirokoff, E; Spieler, H G; Staniszewski, Z; Stark, A A; Vanderlinde, K; Vieira, J D; Vu, C; Westbrook, B; Williamson, R

2012-07-01

A technological milestone for experiments employing transition edge sensor bolometers operating at sub-Kelvin temperature is the deployment of detector arrays with 100s-1000s of bolometers. One key technology for such arrays is readout multiplexing: the ability to read out many sensors simultaneously on the same set of wires. This paper describes a frequency-domain multiplexed readout system which has been developed for and deployed on the APEX-SZ and South Pole Telescope millimeter wavelength receivers. In this system, the detector array is divided into modules of seven detectors, and each bolometer within the module is biased with a unique ∼MHz sinusoidal carrier such that the individual bolometer signals are well separated in frequency space. The currents from all bolometers in a module are summed together and pre-amplified with superconducting quantum interference devices operating at 4 K. Room temperature electronics demodulate the carriers to recover the bolometer signals, which are digitized separately and stored to disk. This readout system contributes little noise relative to the detectors themselves, is remarkably insensitive to unwanted microphonic excitations, and provides a technology pathway to multiplexing larger numbers of sensors.

Synthesis, characterization, antimicrobial activity and DFT studies of 2-(pyrimidin-2-ylamino)naphthalene-1,4-dione and its Mn(II), Co(II), Ni(II) and Zn(II) complexes

NASA Astrophysics Data System (ADS)

Chioma, Festus; Ekennia, Anthony C.; Ibeji, Collins U.; Okafor, Sunday N.; Onwudiwe, Damian C.; Osowole, Aderoju A.; Ujam, Oguejiofo T.

2018-07-01

A pyrimidine-based ligand, 2-(pyrimidin-2-ylamino)naphthalene-1,4-dione (L), has been synthesized by the reaction of 2-aminopyrimidine with 2-hydroxy-1,4-napthoquinone. Reaction of the ligand with Ni(II), Co(II), Mn(II) and Zn(II) acetate gave the corresponding metal complexes which were characterized by spectroscopic techniques, (infrared, electronic), elemental analysis, room-temperature magnetometry, conductance measurements and thermogravimetry-differential scanning calorimetry (TG-DSC) analyses. The room-temperature magnetic data and electronic spectral measurements of the complexes gave evidence of 4-coordinate square planar/tetrahedral geometry. The thermal analyses values obtained indicated the monohydrate complexes. The antimicrobial screening of the compounds showed mild to very good results. The Mn(II) complex showed the best result within in the range of 11.5-29 mm. The electronic, structural and spectroscopic properties of the complexes were further discussed using density functional theory. Molecular docking studies showed significant binding affinity with the drug targets and the metal complexes have potentials to be used as drugs.

Theoretical modeling of the electronic structure and exchange interactions in Cu(II)Pc

NASA Astrophysics Data System (ADS)

Wu, Wei; Fisher, A. J.; Harrison, N. M.; Wang, Hai; Wu, Zhenlin; Gardener, Jules; Heutz, Sandrine; Jones, Tim; Aeppli, Gabriel

2012-12-01

We calculate the electronic structure and exchange interactions in a copper(II)phthalocyanine (Cu(II)Pc) crystal as a one-dimensional molecular chain using hybrid exchange density functional theory (DFT). In addition, the intermolecular exchange interactions are also calculated in a molecular dimer using Green's function perturbation theory (GFPT) to illustrate the underlying physics. We find that the exchange interactions depend strongly on the stacking angle, but weakly on the sliding angle (defined in the text). The hybrid DFT calculations also provide an insight into the electronic structure of the Cu(II)Pc molecular chain and demonstrate that on-site electron correlations have a significant effect on the nature of the ground state, the band gap and magnetic excitations. The exchange interactions predicted by our DFT calculations and GFPT calculations agree qualitatively with the recent experimental results on newly found η-Cu(II)Pc and the previous results for the α- and β-phases. This work provides a reliable theoretical basis for the further application of Cu(II)Pc to molecular spintronics and organic-based quantum information processing.

Theoretical modeling of the electronic structure and exchange interactions in a Cu(II)Pc one-dimensional chain

NASA Astrophysics Data System (ADS)

Wu, Wei; Fisher, A. J.; Harrison, N. M.

2011-07-01

We calculate the electronic structure and exchange interactions in a copper(II)phthalocyanine [Cu(II)Pc] crystal as a one-dimensional molecular chain using hybrid exchange density functional theory (DFT). In addition, the intermolecular exchange interactions are also calculated in a molecular dimer using Green’s function perturbation theory (GFPT) to illustrate the underlying physics. We find that the exchange interactions depend strongly on the stacking angle, but weakly on the sliding angle (defined in the text). The hybrid DFT calculations also provide an insight into the electronic structure of the Cu(II)Pc molecular chain and demonstrate that on-site electron correlations have a significant effect on the nature of the ground state, the band gap, and magnetic excitations. The exchange interactions predicted by our DFT calculations and GFPT calculations agree qualitatively with the recent experimental results on newly found η-Cu(II)Pc and the previous results for the α and β phases. This work provides a reliable theoretical basis for the further application of Cu(II)Pc to molecular spintronics and organic-based quantum information processing.

Investigation of Electron Loss Processes in CO2/He/N2 Electric Discharges.

DTIC Science & Technology

1980-12-01

Background......................4 Structure of a Discharge. ............. 4 Electron Kinetics..................7 Plasma Chemistry .................. 14...Electron Kinetic Reactions. ............ 11 II C 2/IN 2/He Electron Kinetics ............ 15 III Plasma Chemistry Reactions. ............ 17 IV...effects (Ref 2:317- 323). Table II also lists some of the reactions they found to be possibly important. Plasma Chemistry In order to understand what is

Electronic structure and chemical bonding of the electron-poor II-V semiconductors ZnSb and ZnAs

NASA Astrophysics Data System (ADS)

Benson, Daryn; Sankey, Otto F.; Häussermann, Ulrich

2011-09-01

The binary compounds ZnSb and ZnAs with the CdSb structure are semiconductors (II-V), although the average electron concentration (3.5 per atom) is lower than that of the tetrahedrally bonded III-V and II-VI archetype systems (four per atom). We report a detailed electronic structure and chemical bonding analysis for ZnSb and ZnAs based on first-principles calculations. ZnSb and ZnAs are compared to the zinc blende-type semiconductors GaSb, ZnTe, GaAs, and ZnSe, as well as the more ionic, hypothetical, II-V systems MgSb and MgAs. We establish a clearly covalent bonding scenario for ZnSb and ZnAs where multicenter bonded structural entities (rhomboid rings Zn2Sb2 and Zn2As2) are connected to each other by classical two-center, two-electron bonds. This bonding scenario is only compatible with a weak ionicity in II-V semiconductor systems, and weak ionicity appears as a necessary condition for the stability of the CdSb structure type. It is argued that a chemical bonding scenario with mixed multicenter and two-center bonding resembles that of boron and boron-rich compounds and is typical of electron-poor sp-bonded semiconductors with average valence electron concentrations below four per atom.

Copper and the oxidation of hemoglobin: a comparison of horse and human hemoglobins.

PubMed

Rifkind, J M; Lauer, L D; Chiang, S C; Li, N C

1976-11-30

Oxidation studies of hemoglobin by Cu(II) indicate that for horse hemoglobin, up to a Cu(II)/heme molar ratio of 0.5, all of the Cu(II) added is used to rapidly oxidize the heme. On the other hand, most of the Cu(II) added to human hemoglobin at low Cu(II)/heme molar ratios is unable to oxidize the heme. Only at Cu(II)/heme molar ratios greater than 0.5 does the amount of oxidation per added Cu(II) approach that of horse hemoglobin. At the same time, binding studies indicate that human hemoglobin has an additional binding site involving one copper for every two hemes, which has a higher copper affinity than the single horse hemoglobin binding site. The Cu(II) oxidation of human hemoglobin is explained utilizing this additional binding site by a mechanism where a transfer of electrons cannot occur between the heme and the Cu(II) bound to the high affinity human binding site. The electron transfer must involve the Cu(II) bound to the lower affinity human hemoglobin binding site, which is similar to the only horse hemoglobin site. The involvement of beta-2 histidine in the binding of this additional copper is indicated by a comparison of the amino acid sequences of various hemoglobins which possess the additional site, with the amino acid sequences of hemoglobins which do not possess the additional site. Zn(II), Hg(II), and N-ethylmaleimide (NEM) are found to decrease the Cu(II) oxidation of hemoglobin. The sulfhydryl reagents, Hg(II) and NEM, produce a very dramatic decrease in the rate of oxidation, which can only be explained by an effect on the rate for the actual transfer of electrons between the Cu(II) and the Fe(II). The effect of Zn(II) is much smaller and can, for the most part, be explained by the increased oxygen affinity, which affects the ligand dissociation process that must precede the electron transfer process.

Experimental electron energy-loss spectra and cross sections for the 4/2/S - 4/2/P transition in Zn II

NASA Technical Reports Server (NTRS)

Chutjian, A.; Newell, W. R.

1982-01-01

Electron energy-loss spectra and differential cross sections are reported for inelastic scattering from Zn II. Measurements were carried out in a crossed electron beam-ion beam apparatus, at incident electron energies of 30, 40, 50, 60, 75, 85, and 100 eV, and at a scattering angle of 14 deg. The present results are the first reported measurements of inelastic electron scattering from an ion.

Impact of nitrophenols on the photosynthetic electron transport chain and ATP content in Nostoc muscorum and Chlorella vulgaris.

PubMed

Umamaheswari, A; Venkateswarlu, K

2004-06-01

Concentration-dependent inhibition of the photosynthetic electron transport chain (photosystem I (PS I), photosystem II (PS II) and whole chain reaction) and ATP content was observed in Nostoc muscorum and Chlorella vulgaris grown with o-nitrophenol, m-nitrophenol, or 2,4-dinitrophenol. Although the extents of inhibition of the photosynthetic electron transport chain in both organisms were similar, PS II was more sensitive than PS I and whole chain reaction to the nitrophenols. Depletion of the ATP pool was noted in nitrophenol-grown cultures, probably as a consequence of nearly complete inhibition of the photosynthetic electron transport chain.

The ELISE II Project: A Digital Image Library for Europe.

ERIC Educational Resources Information Center

Strunz, Bob; Waters, Mairead

This paper describes the progress made under the ELISE II electronic image library project from a technical standpoint. The ELISE II project is a European-wide initiative that aims to provide a comprehensive electronic image library service for Europe. It is funded under the European Commission, DG XIII-E, Telematics for Libraries Initiative. The…

Mononuclear Copper Complex Catalyzed Four-Electron Reduction of Oxygen

PubMed Central

Fukuzumi, Shunichi; Kotani, Hiroaki; Lucas, Heather R.; Doi, Kaoru; Suenobu, Tomoyoshi; Peterson, Ryan L.; Karlin, Kenneth D.

2010-01-01

A mononuclear CuII complex acts as an efficient catalyst for four-electron reduction of O2 to H2O by a ferrocene derivative via formation of the dinuclear CuII peroxo complex that is further reduced in the presence of protons by a ferrocene derivative to regenerate the CuII complex. PMID:20443560

A first principles investigation of electron transfer between Fe(II) and U(VI) on insulating Al- vs. semiconducting Fe-oxide surfaces via the proximity effect

NASA Astrophysics Data System (ADS)

Taylor, S. D.; Marcano, M. C.; Becker, U.

2017-01-01

This study investigates how the intrinsic chemical and electronic properties of mineral surfaces and their associated electron transfer (ET) pathways influence the reduction of U(VI) by surface-associated Fe(II). Density functional theory (DFT), including the Hubbard U correction to the exchange-correlation functional, was used to investigate sorption/redox reactions and ET mechanisms between Fe(II) and U(VI) coadsorbed on isostructural, periodic (0 0 1) surfaces of the insulator corundum (α-Al2O3) vs. the semiconductor hematite (α-Fe2O3). Furthermore, the coadsorbed Fe(II) and U(VI) ions are spatially separated from one another on the surfaces (⩾5.9 Å) to observe whether electronic-coupling through the semiconducting hematite surface facilitates ET between the adsorbates, a phenomenon known as the proximity effect. The calculations show that the different chemical and electronic properties between the isostructural corundum and hematite (0 0 1) surfaces lead to considerably different ET mechanisms between Fe(II) and U(VI). ET on the insulating corundum (0 0 1) surface is limited by the adsorbates' structural configuration. When Fe(II) and U(VI) are spatially separated and do not directly interact with one another (e.g. via an inner-sphere complex), U(VI) reduction by Fe(II) cannot occur as there is no physical pathway enabling ET between the adsorbates. In contrast to the insulating corundum (0 0 1) surface, the hematite (0 0 1) surface can potentially participate in ET reactions due to the high number of electron acceptor sites from the Fe d-states near the Fermi level at the hematite surface. The adsorption of Fe(II) also introduces d-states near the Fermi level as well as shifts unoccupied d-states of the Fe cations at the hematite surface to lower energies, making the surface more conductive. In turn, electronic coupling through the surface can link the spatially separated adsorbates to one another and provide distinct ET pathways for an electron from Fe(II) to travel through the hematite surface and reach U(VI). The progression and extent of ET occurring on the semiconducting hematite (0 0 1) surface via the proximity effect depends on the electronic properties of the surface. ET between the spatially separated U(VI) and Fe(II) occurs most readily when orbitals between the Fe and U adsorbates overlap with those of neighboring O and Fe ions at the hematite surface, as shown by calculations without the Hubbard U correction. Analyses of the spins densities confirm that the U and Fe adsorbates were reduced and oxidized, respectively, (acquiring 0.33 μB and 0.11-0.20 μB, respectively), while Fe cations at the hematite surface were reduced (losing ⩽0.6 μB). If electrons are highly localized, the amount of orbital mixing and electronic coupling through the hematite surface decreases and in turn leads to a lower degree of spin transfer, as predicted by calculations with the Hubbard U correction. Thus, the proximity effect is a potential mechanism on semiconducting surfaces facilitating surface-mediated redox reactions, although its significance varies depending on the electronic properties and subsequent charge-carrying ability of the surface. These results provide insight into ET pathways and mechanisms on insulating Al- and semiconducting Fe oxide surfaces influencing the reduction U(VI) by Fe(II) that may subsequently limit uranium's transport in the subsurface.

Manganese binding properties of human calprotectin under conditions of high and low calcium: X-ray crystallographic and advanced electron paramagnetic resonance spectroscopic analysis.

PubMed

Gagnon, Derek M; Brophy, Megan Brunjes; Bowman, Sarah E J; Stich, Troy A; Drennan, Catherine L; Britt, R David; Nolan, Elizabeth M

2015-03-04

The antimicrobial protein calprotectin (CP), a hetero-oligomer of the S100 family members S100A8 and S100A9, is the only identified mammalian Mn(II)-sequestering protein. Human CP uses Ca(II) ions to tune its Mn(II) affinity at a biologically unprecedented hexahistidine site that forms at the S100A8/S100A9 interface, and the molecular basis for this phenomenon requires elucidation. Herein, we investigate the remarkable Mn(II) coordination chemistry of human CP using X-ray crystallography as well as continuous-wave (CW) and pulse electron paramagnetic resonance (EPR) spectroscopies. An X-ray crystallographic structure of Mn(II)-CP containing one Mn(II), two Ca(II), and two Na(I) ions per CP heterodimer is reported. The CW EPR spectrum of Ca(II)- and Mn(II)-bound CP prepared with a 10:0.9:1 Ca(II):Mn(II):CP ratio is characterized by an unusually low zero-field splitting of 485 MHz (E/D = 0.30) for the S = 5/2 Mn(II) ion, consistent with the high symmetry of the His6 binding site observed crystallographically. Results from electron spin-echo envelope modulation and electron-nuclear double resonance experiments reveal that the six Mn(II)-coordinating histidine residues of Ca(II)- and Mn(II)-bound CP are spectroscopically equivalent. The observed (15)N (I = 1/2) hyperfine couplings (A) arise from two distinct classes of nitrogen atoms: the coordinating ε-nitrogen of the imidazole ring of each histidine ligand (A = [3.45, 3.71, 5.91] MHz) and the distal δ-nitrogen (A = [0.11, 0.18, 0.42] MHz). In the absence of Ca(II), the binding affinity of CP for Mn(II) drops by two to three orders of magnitude and coincides with Mn(II) binding at the His6 site as well as other sites. This study demonstrates the role of Ca(II) in enabling high-affinity and specific binding of Mn(II) to the His6 site of human calprotectin.

Collisional excitation and radiative properties of N II - The strong intercombination (1D - 3P0) transition at 748 A

NASA Technical Reports Server (NTRS)

Tripp, T. M.; Shemansky, D. E.; James, G. K.; Ajello, J. M.

1991-01-01

Laboratory measurements of EUV emission from electron-excited N2 have been obtained at medium resolution, providing N II EUV emission cross section measurements and allowing the confirmation of recent calculations by Fawcett (1987) indicating the presence of a strong intercombination line in N II at 748.37 A. The most recently available data are used to predict the basic collisional and radiative properties of N II, the plasma diagnostic properties are briefly explored, and radiative cooling coefficients are given. Some basic properties of electron-excited N II and N2 are examined in the EUV in order to diagnose emission spectra of the earth and Titan. The N II emissions in the earth dayglow, particularly at 916 A, are much brighter than current estimates of source rates. The N II 1085 A line in the dayglow contains a significant component from dissociative photoionization excitation. The N II 1085 A, 916 A, and 670 A lines in the Titan dayglow spectrum appear to be compatible with direct electron excitation of N2.

Some characteristic features of the construction of the amplifying channel for working with semiconductor detectors in the charged particle energy spectrometer. [noise minimization at preamplifier input

NASA Technical Reports Server (NTRS)

Kuzyuta, E. I.

1974-01-01

A transistorized spectrometric amplifier with a shaper is reported that selects the shape of the frequency characteristic of the amplifying channel for which the primary frequency spectrum of the signal will pass, but where the noise spectrum is limited to the maximum. A procedure is presented for selecting the shaping circuits and their inclusion principles.

Receiver design, performance analysis, and evaluation for space-borne laser altimeters and space-to-space laser ranging systems

NASA Technical Reports Server (NTRS)

Davidson, Frederic M.; Sun, Xiaoli; Field, Christopher T.

1994-01-01

This interim report consists of two reports: 'Space Radiation Effects on Si APDs for GLAS' and 'Computer Simulation of Avalanche Photodiode and Preamplifier Output for Laser Altimeters.' The former contains a detailed description of our proton radiation test of Si APD's performed at the Brookhaven National Laboratory. The latter documents the computer program subroutines which were written for the upgrade of NASA's GLAS simulator.

Frequency-Agile LIDAR Receiver for Chemical and Biological Agent Sensing

DTIC Science & Technology

2010-06-01

transimpedance preamplifier architecture was optimized around the selected IR detector diode – Input-referenced noise density of 0.8 nV/ Hz0.5  A portion of...objectives: • Reduce baseline (background) photon flux on detector : Tunable Fabry-Perot etalon in optical train • Reduce input-referenced amplifier noise ...custom amplifier • Reduce detector dark current: High impedance detector  Performance Metrics: – Noise equivalent power of receiver system (NEP

Coherent Path Beamformer Front End for High Performance Acoustic Modems

DTIC Science & Technology

1999-09-30

transmission underwater. This knowledge will be used to develop a test model for evaluating under water acoustic modem and other shallow water sonar ...rates can be achieved, as shown in the following two sections. WORK COMPLETED Two systems have been developed in the Sonar Laboratory of Ocean...2) More performant variable gain preamplifiers have been installed and the software updated for a better control of the dynamic range. 3) An

DINS Final Report.

DTIC Science & Technology

1979-10-19

A optical input from a laser ggw system . The photodetector assembly shall consist of two chips: (1) photodiode chip and (2) preamplifier chip. The...181 4.1 Transienit Gamm ------ - 182 4.2 Therm~al Noise ------------------- 186 2 1 System F’unatioma Diagram -B 2 Bonding...5 2u.0 ed IG o Hl MM The desJign reurnents of the DIM~ Pbto detector System are - The system sball 1eev a 300 nhnowatt, (Min.) 63282 signal from a

Test Methods for Telemetry Systems and Subsystems. Volume 2: Test Methods for Telemetry Radio Frequency (RF) Subsystems

DTIC Science & Technology

2012-09-01

downconverters; telemetry RF preamplifiers; telemetry multicouplers; telemetry receivers 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT Same as...Continuing Engineering Education Program, George Washington University , 1994. A-5 Figure A-2. Graphical representation of intercept point...NFdb) is expressed in decibels and noise factor (nf ) in decimal units. For example, a noise figure of 3 dB corresponds to a noise factor of 2

Direct measurements of intramolecular electron transfer rates between cytochrome c and cytochrome c peroxidase: effects of exothermicity and primary sequence on rate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheung, E.; Taylor, K.; Kornblatt, J.A.

1986-03-01

Rapid mixing of ferrocytochrome c peroxidase (cyt c peroxidase(II)) and ferricytochrome c (cyt c(III)) results in the reduction of cyt c(III) by cyt c peroxidase(II). In 10 mM phosphate, pH 7.0, the rate of decay of cyt c peroxidase(II) and the rate of accumulation of cyt c(II) give equal first-order rate constants. Equivalent results are obtained by pulse radiolysis using isopropanol radical as the reducing agent. This rate is independent of the initial cyt c(III):cyt c peroxidase(II) ratios. These results are consistent with unimolecular electron transfer occurring within a cyt c(III)-cyt c peroxidase(II) complex. When cyt c is replaced bymore » porphyrin cyt c (iron-free cyt c), a complex still forms with cyt c peroxidase. On radiolysis intracomplex electron transfer occurs from the porphyrin cyt c anion radical to cyt c peroxidase(III). This large rate increase suggest that the barrier for intracomplex electron transfer is large. Finally, the authors have briefly investigated how the cyt c peroxidase(II) ..-->.. cyt c(III) rate depends on the primary structure of cyt c(III). They find the reactivity order to be as follows: yeast > horse > tuna.« less

Surface Mn(II) oxidation actuated by a multicopper oxidase in a soil bacterium leads to the formation of manganese oxide minerals

PubMed Central

Zhang, Zhen; Zhang, Zhongming; Chen, Hong; Liu, Jin; Liu, Chang; Ni, Hong; Zhao, Changsong; Ali, Muhammad; Liu, Fan; Li, Lin

2015-01-01

In this manuscript, we report that a bacterial multicopper oxidase (MCO266) catalyzes Mn(II) oxidation on the cell surface, resulting in the surface deposition of Mn(III) and Mn(IV) oxides and the gradual formation of bulky oxide aggregates. These aggregates serve as nucleation centers for the formation of Mn oxide micronodules and Mn-rich sediments. A soil-borne Escherichia coli with high Mn(II)-oxidizing activity formed Mn(III)/Mn(IV) oxide deposit layers and aggregates under laboratory culture conditions. We engineered MCO266 onto the cell surfaces of both an activity-negative recipient and wild-type strains. The results confirmed that MCO266 governs Mn(II) oxidation and initiates the formation of deposits and aggregates. By contrast, a cell-free substrate, heat-killed strains, and intracellularly expressed or purified MCO266 failed to catalyze Mn(II) oxidation. However, purified MCO266 exhibited Mn(II)-oxidizing activity when combined with cell outer membrane component (COMC) fractions in vitro. We demonstrated that Mn(II) oxidation and aggregate formation occurred through an oxygen-dependent biotic transformation process that requires a certain minimum Mn(II) concentration. We propose an approximate electron transfer pathway in which MCO266 transfers only one electron to convert Mn(II) to Mn(III) and then cooperates with other COMC electron transporters to transfer the other electron required to oxidize Mn(III) to Mn(IV). PMID:26039669

Surface Mn(II) oxidation actuated by a multicopper oxidase in a soil bacterium leads to the formation of manganese oxide minerals.

PubMed

Zhang, Zhen; Zhang, Zhongming; Chen, Hong; Liu, Jin; Liu, Chang; Ni, Hong; Zhao, Changsong; Ali, Muhammad; Liu, Fan; Li, Lin

2015-06-03

In this manuscript, we report that a bacterial multicopper oxidase (MCO266) catalyzes Mn(II) oxidation on the cell surface, resulting in the surface deposition of Mn(III) and Mn(IV) oxides and the gradual formation of bulky oxide aggregates. These aggregates serve as nucleation centers for the formation of Mn oxide micronodules and Mn-rich sediments. A soil-borne Escherichia coli with high Mn(II)-oxidizing activity formed Mn(III)/Mn(IV) oxide deposit layers and aggregates under laboratory culture conditions. We engineered MCO266 onto the cell surfaces of both an activity-negative recipient and wild-type strains. The results confirmed that MCO266 governs Mn(II) oxidation and initiates the formation of deposits and aggregates. By contrast, a cell-free substrate, heat-killed strains, and intracellularly expressed or purified MCO266 failed to catalyze Mn(II) oxidation. However, purified MCO266 exhibited Mn(II)-oxidizing activity when combined with cell outer membrane component (COMC) fractions in vitro. We demonstrated that Mn(II) oxidation and aggregate formation occurred through an oxygen-dependent biotic transformation process that requires a certain minimum Mn(II) concentration. We propose an approximate electron transfer pathway in which MCO266 transfers only one electron to convert Mn(II) to Mn(III) and then cooperates with other COMC electron transporters to transfer the other electron required to oxidize Mn(III) to Mn(IV).

Zn(II), Cd(II) and Hg(I) complexes of cinnamic acid: FT-IR, FT-Raman, 1H and 13C NMR studies

NASA Astrophysics Data System (ADS)

Kalinowska, M.; Świsłocka, R.; Lewandowski, W.

2011-05-01

The effect of zinc, cadmium(II) and mercury(I) ions on the electronic structure of cinnamic acid (phenylacrylic acid) was studied. In this research many miscellaneous analytical methods, which complement one another, were used: infrared (FT-IR), Raman (FT-Raman), nuclear magnetic resonance ( 1H, 13C NMR) and quantum mechanical calculations. The spectroscopic studies provide some knowledge on the distribution of the electronic charge in molecule, the delocalization energy of π-electrons and the reactivity of metal complexes. In the series of Zn(II) → Cd(II) → Hg(I) cinnamates: (1) systematic shifts of several bands in the experimental and theoretical IR and Raman spectra and (2) regular chemical shifts for protons 1H and 13C nuclei were observed.

Electron spin echo envelope modulation studies of the Cu(II)-substituted derivative of isopenicillin N synthase: A structural and spectroscopic model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng Jiang; Peisach, J.; Lijune Ming

Electron spin echo envelope modulation spectroscopy (ESEEM) was used to study the active site structure of isopenicillin N synthase (IPNS) from Cephalosporium acremonium with Cu(II) as a spectroscopic probe. Fourier transform of the simulated electron spin-echo envelope for the Cu(II)-substituted enzyme, Cu(II)IPNS, revealed two nearly magnetically equivalent, equatorially coordinated His imidazoles. The superhyperfine coupling constant, A{sub iso}, for the remote {sup 14}N of each imidazole was 1.65 MHz. The binding of substrate to the enzyme altered the magnetic coupling so that A{sub iso} is 1.30 MHz for one nitrogen and 2.16 MHz for the other. From a comparison of themore » ESSEM of Cu(II)IPNS in D{sub 2}O and H{sub 2}O, it is suggested that water is a ligand of Cu(II) and this is displaced upon the addition of substrate.« less

Substrate-controlled Rh(II)-catalyzed single-electron-transfer (SET): divergent synthesis of fused indoles.

PubMed

Chen, Kai; Zhu, Zi-Zhong; Liu, Jia-Xin; Tang, Xiang-Ying; Wei, Yin; Shi, Min

2016-01-07

Rh(II)-catalyzed diversified ring expansions controlled by single-electron-transfer (SET) have been disclosed in this communication, producing a series of indole-fused azetidines and 1H-carbazoles or related derivatives in moderate to good yields via Rh2(III,II) nitrene radical intermediates. The direction of ring expansion branches according to different ring sizes of methylenecycloalkanes.

Cloud Top Scanning radiometer (CTS)

NASA Technical Reports Server (NTRS)

1978-01-01

A scanning radiometer to be used for measuring cloud radiances in each of three spectral regions is described. Significant features incorporated in the Cloud Top Scanner design are: (1) flexibility and growth potential through use of easily replaceable modular detectors and filters; (2) full aperture, multilevel inflight calibration; (3) inherent channel registration through employment of a single shared field stop; and (4) radiometric sensitivity margin in a compact optical design through use of Honeywell developed (Hg,Cd)Te detectors and preamplifiers.

Digital pulse processing for planar TlBr detectors

NASA Astrophysics Data System (ADS)

Nakhostin, M.; Hitomi, K.; Ishii, K.; Kikuchi, Y.

2010-04-01

We report on a digital pulse processing algorithm for correction of charge trapping in the planar TlBr detectors. The algorithm is performed on the signals digitized at the preamplifier stage. The algorithm is very simple and is implemented with little computational effort. By using a digitizer with a sampling rate of 250 MSample/s and 8 bit resolution, an energy resolution of 6.5% is achieved at 511 keV with a 0.7 mm thick detector.

Electromagnetic Radiation from Corona Discharges.

DTIC Science & Technology

1977-01-25

a 3 MHz bandwidth to cover frequencies below I GHz. Various TWT preamplifiers were used to increase the system gain. R-f energy from the corona point...100 MHz CENTER FREQUENCYr 0.05 mv/div 5 ps/div FIGURE 11. DETECTED I.F SIGNALS RECEIVED FROM A 20’ PIPE IN CORONA 29 the broadband impulsive background...noise at sea, with a secondary objective of measuring background noise at narrower bandwidths on a swept frequency basis. The broadband measurement

Status of the isophot detector development

NASA Technical Reports Server (NTRS)

Wolf, J.; Lemke, D.; Burgdorf, M.; Groezinger, U.; Hajduk, CH.

1989-01-01

ISOPHOT is one of the four focal plane experiments of the European Space Agency's Infrared Space Observatory (ISO). Scheduled for a 1993 launch, it will operate extrinsic silicon and germanium photoconductors at low temperature and low background during the longer than 18 month mission. These detectors cover the wavelength range from 2.5 to 200 microns and are used as single elements and in arrays. A cryogenic preamplifier was developed to read out a total number of 223 detector pixels.

Circular zig-zag scan video format

DOEpatents

Peterson, C. Glen; Simmons, Charles M.

1992-01-01

A circular, ziz-zag scan for use with vidicon tubes. A sine wave is generated, rectified and its fourth root extracted. The fourth root, and its inverse, are used to generate horizontal ramp and sync signals. The fourth root is also used to generate a vertical sync signal, and the vertical sync signal, along with the horizontal sync signal, are used to generate the vertical ramp signal. Cathode blanking and preamplifier clamp signals are also obtained from the vertical sync signal.

Thematic mapper critical elements breadboard program

NASA Technical Reports Server (NTRS)

Dale, C. H., Jr.; Engel, J. L.; Harney, E. D.

1976-01-01

A 40.6 cm bidirectional scan mirror assembly, a scan line corrector and a silicon photodiode array with integral preamplifier input stages were designed, fabricated, and tested to demonstrate performance consistent with requirements of the Hughes thematic mapper system. The measured performance met or exceeded the original design goals in all cases with the qualification that well defined and well understood deficiencies in the design of the photodiode array package will require the prescribed corrections before flight use.

Data acquisition channel apparatus

NASA Astrophysics Data System (ADS)

Higgins, C. H.; Skipper, J. D.

1985-10-01

Dicussed is a hybrid integrated circuit data acquisition channel apparatus employing an operational amplifier fed by a low current differential bipolar transistor preamplifier having separate feedback gain and signal gain determining elements and providing an amplified signal output to a sample and hold and analog-to-digital converter circuits. The disclosed apparatus operates with low energy and small space requirements and is capable of operations without the sample and hold circuit where the nature of the applied input signal permits.

Comparative absorption, electroabsorption and electrochemical studies of intervalence electron transfer and electronic coupling in cyanide-bridged bimetallic systems: ancillary ligand effects

NASA Astrophysics Data System (ADS)

Vance, Fredrick W.; Slone, Robert V.; Stern, Charlotte L.; Hupp, Joseph T.

2000-03-01

Electroabsorption or Stark spectroscopy has been used to evaluate the systems (NC) 5M II-CN-Ru III(NH 3) 51- and (NC) 5M II-CN-Ru III(NH 3) 4py 1-, where M II=Fe II or Ru II. When a pyridine ligand is present in the axial position on the Ru III acceptor, the effective optical electron transfer distance - as measured by the change in dipole moment, |Δ μ| - is increased by more than 35% relative to the ammine substituted counterpart. Comparison of the charge transfer distances to the crystal structure of Na[(CN) 5Fe-CN-Ru(NH 3) 4py] · 6H 2O reveals that the Stark derived distances are ˜50% to ˜90% of the geometric separation of the metal centers. The differences result in an upward revision in the Hush delocalization parameter, c b2, and of the electronic coupling matrix element, H ab, relative to those parameters obtained exclusively from electronic absorption measurements. The revised parameters are compared to those, which are obtained via electrochemical techniques and found to be in only fair agreement. We conclude that the absorption/electroabsorption analysis likely yields a more reliable set of mixing and coupling parameters.

Electron transfer flavoprotein domain II orientation monitored using double electron-electron resonance between an enzymatically reduced, native FAD cofactor, and spin labels

PubMed Central

Swanson, Michael A; Kathirvelu, Velavan; Majtan, Tomas; Frerman, Frank E; Eaton, Gareth R; Eaton, Sandra S

2011-01-01

Human electron transfer flavoprotein (ETF) is a soluble mitochondrial heterodimeric flavoprotein that links fatty acid β-oxidation to the main respiratory chain. The crystal structure of human ETF bound to medium chain acyl-CoA dehydrogenase indicates that the flavin adenine dinucleotide (FAD) domain (αII) is mobile, which permits more rapid electron transfer with donors and acceptors by providing closer access to the flavin and allows ETF to accept electrons from at least 10 different flavoprotein dehydrogenases. Sequence homology is high and low-angle X-ray scattering is identical for Paracoccus denitrificans (P. denitrificans) and human ETF. To characterize the orientations of the αII domain of P. denitrificans ETF, distances between enzymatically reduced FAD and spin labels in the three structural domains were measured by double electron-electron resonance (DEER) at X- and Q-bands. An FAD to spin label distance of 2.8 ± 0.15 nm for the label in the FAD-containing αII domain (A210C) agreed with estimates from the crystal structure (3.0 nm), molecular dynamics simulations (2.7 nm), and rotamer library analysis (2.8 nm). Distances between the reduced FAD and labels in αI (A43C) were between 4.0 and 4.5 ± 0.35 nm and for βIII (A111C) the distance was 4.3 ± 0.15 nm. These values were intermediate between estimates from the crystal structure of P. denitrificans ETF and a homology model based on substrate-bound human ETF. These distances suggest that the αII domain adopts orientations in solution that are intermediate between those which are observed in the crystal structures of free ETF (closed) and ETF bound to a dehydrogenase (open). PMID:21308847

Electronic monitoring and voice prompts improve hand hygiene and decrease nosocomial infections in an intermediate care unit.

PubMed

Swoboda, Sandra M; Earsing, Karen; Strauss, Kevin; Lane, Stephen; Lipsett, Pamela A

2004-02-01

To determine whether electronic monitoring of hand hygiene and voice prompts can improve hand hygiene and decrease nosocomial infection rates in a surgical intermediate care unit. Three-phase quasi-experimental design. Phase I was electronic monitoring and direct observation; phase II was electronic monitoring and computerized voice prompts for failure to perform hand hygiene on room exit; and phase III was electronic monitoring only. Nine-room, 14-bed intermediate care unit in a university, tertiary-care institution. All patient rooms, utility room, and staff lavatory were monitored electronically. All healthcare personnel including physicians, nurses, nursing support personnel, ancillary staff, all visitors and family members, and any other personnel interacting with patients on the intermediate care unit. All patients with an intermediate care unit length of stay >48 hrs were followed for nosocomial infection. Electronic monitoring during all phases, computerized voice prompts during phase II only. We evaluated a total of 283,488 electronically monitored entries into a patient room with 251,526 exits for 420 days (10,080 hrs and 3,549 patient days). Compared with phase I, hand hygiene compliance in patient rooms improved 37% during phase II (odds ratio, 1.38; 95% confidence interval, 1.04-1.83) and 41% in phase III (odds ratio, 1.41; 95% confidence interval, 1.07-1.84). When adjusting for patient admissions during each phase, point estimates of nosocomial infections decreased by 22% during phase II and 48% during phase III; when adjusting for patient days, the number of infections decreased by 10% during phase II and 40% during phase III. Although the overall rate of nosocomial infections significantly decreased when combining phases II and III, the association between nosocomial infection and individual phase was not significant. Electronic monitoring provided effective ongoing feedback about hand hygiene compliance. During both the voice prompt phase and post-intervention phase, hand hygiene compliance and nosocomial infection rates improved suggesting that ongoing monitoring and feedback had both a short-term and, perhaps, a longer-term effect.

Interfacial charge separation and photovoltaic efficiency in Fe(ii)-carbene sensitized solar cells.

PubMed

Pastore, Mariachiara; Duchanois, Thibaut; Liu, Li; Monari, Antonio; Assfeld, Xavier; Haacke, Stefan; Gros, Philippe C

2016-10-12

The first combined theoretical and photovoltaic characterization of both homoleptic and heteroleptic Fe(ii)-carbene sensitized photoanodes in working dye sensitized solar cells (DSSCs) has been performed. Three new heteroleptic Fe(ii)-NHC dye sensitizers have been synthesized, characterized and tested. Despite an improved interfacial charge separation in comparison to the homoleptic compounds, the heteroleptic complexes did not show boosted photovoltaic performances. The ab initio quantitative analysis of the interfacial electron and hole transfers and the measured photovoltaic data clearly evidenced fast recombination reactions for heteroleptics, even associated with un unfavorable directional electron flow, and hence slower injection rates, in the case of homoleptics. Notably, quantum mechanics calculations revealed that deprotonation of the not anchored carboxylic function in the homoleptic complex can effectively accelerate the electron injection rate and completely suppress the electron recombination to the oxidized dye. This result suggests that introduction of strong electron-donating substituents on the not-anchored carbene ligand in heteroleptic complexes, in such a way of mimicking the electronic effects of the carboxylate functionality, should yield markedly improved interfacial charge generation properties. The present results, providing for the first time a detailed understanding of the interfacial electron transfers and photovoltaic characterization in Fe(ii)-carbene sensitized solar cells, open the way to a rational molecular engineering of efficient iron-based dyes for photoelectrochemical applications.

Lewis Acid-Induced Change from Four- to Two-Electron Reduction of Dioxygen Catalyzed by Copper Complexes Using Scandium Triflate

PubMed Central

Kakuda, Saya; Rolle, Clarence; Ohkubo, Kei; Siegler, Maxime A.; Karlin, Kenneth D.; Fukuzumi, Shunichi

2015-01-01

Mononuclear copper complexes, [(tmpa)CuII(CH3CN)](ClO4)2 (1, tmpa = tris(2-pyridylmethyl)amine) and [(BzQ)CuII(H2O)2](ClO4)2 (2, BzQ = bis(2-quinolinylmethyl)benzylamine)], act as efficient catalysts for the selective two-electron reduction of O2 by ferrocene derivatives in the presence of scandium triflate (Sc(OTf)3), in acetone, whereas 1 catalyzes the four-electron reduction of O2 by the same reductant in the presence of Brønsted acids such as triflic acid. Following formation of the peroxo-bridged dicopper(II) complex [(tmpa)CuII(O2)CuII(tmpa)]2+, the two-electron reduced product of O2 with Sc3+ is observed to be scandium peroxide ([Sc3+(O22−)]+). In the presence of three equiv of hexamethylphosphoric triamide (HMPA), [Sc3+(O22−)]+ was oxidized by [Fe(bpy)3]3+ (bpy = 2,2′-bipyridine) to the known superoxide species [(HMPA)3Sc3+(O2•−)]2+ as detected by EPR spectroscopy. A kinetic study revealed that the rate-determining step of the catalytic cycle for the two-electron reduction of O2 with 1 is electron transfer from Fc* to 1 to give a cuprous complex which is highly reactive toward O2, whereas the rate-determining step with 2 is changed to the reaction of the cuprous complex with O2 following electron transfer from ferrocene derivatives to 2. The explanation for the change in catalytic O2-reaction stoichiometry from four-electron with Brønsted acids to two-electron reduction in the presence of Sc3+ and also for the change in the rate-determining step is clarified based on a kinetics interrogation of the overall catalytic cycle as well as each step of the catalytic cycle with study of the observed effects of Sc3+ on copper-oxygen intermediates. PMID:25659416

Decoupling optical and potentiometric band gaps in pi-conjugated materials.

PubMed

Susumu, Kimihiro; Therien, Michael J

2002-07-24

Syntheses, optical spectroscopy, potentiometric studies, and electronic structural calculations are reported for two classes of conjugated (porphinato)metal oligomers that feature a meso-to-meso ethyne-bridged linkage topology. One set of these systems, bis[(5,5'-10,20-bis[3,5-bis(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]ethyne (DD), 5,15-bis[[5'-10',20'-bis[3,5-di(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]ethynyl]-10,20-bis[3,5-di(9-methoxy-1,4,7-trioxanonyl)phenyl]porphinato)zinc(II) (DDD), and 5,15-bis[[15' '-(5'-10',20'-bis[3,5-bis(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]-[(5' '-10' ',20' '-bis[3,5-di(9-methoxy-1,4,7-trioxanonyl)phenyl]porphinato)zinc(II)]ethyne]ethynyl]-10,20-bis[3,5-di(9-methoxy-1,4,7-trioxanonyl)phenyl]porphinato)zinc(II) (DDDDD), constitute highly soluble analogues of previously studied examples of this structural motif having simple 10,20-diaryl substituents, while a corresponding set of conjugated oligomers, [(5-10,20-bis[3,5-bis(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]-[(5'-15'-ethynyl-10',20'-bis[10,20-bis(heptafluoropropyl)porphinato)zinc(II)]ethyne (DA), 5,15-bis[[5'-10',20'-bis[3,5-di(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]ethynyl]-10,20-bis(heptafluoropropyl)porphinato]zinc(II) (DAD), and 5,15-bis[[15' '-(5'-10',20'-bis[3,5-bis(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]-[(5' '-(10' ',20' '-bis(heptafluoropropyl)porphinato)zinc(II)]ethyne]ethynyl]-10,20-bis[3,5-di(9-methoxy-1,4,7-trioxanonyl)phenyl]porphinato)zinc(II) (DADAD), features alternating electron-rich and electron-poor (porphinato)zinc(II) units. Electrooptic and computational data for these species demonstrate that it is possible to engineer conjugated oligomeric structures that possess highly delocalized singlet (S1) excited states yet manifest apparent one-electron oxidation and reduction potentials (E1/20/+ and E1/2-/0 values) that are essentially invariant with respect to those elucidated for their constituent monomeric precursors.

Quasiparticle scattering in type-II Weyl semimetal MoTe2

NASA Astrophysics Data System (ADS)

Lin, Chun-Liang; Arafune, Ryuichi; Minamitani, Emi; Kawai, Maki; Takagi, Noriaki

2018-03-01

The electronic structure of type-II Weyl semimetal molybdenum ditelluride (MoTe2) is studied by using scanning tunneling microscopy and density functional theory calculations. Through measuring energy-dependent quasiparticle interference (QPI) patterns with a cryogenic scanning tunneling microscope, several characteristic features are found in the QPI patterns. Two of them arise from the Weyl semimetal nature; one is the topological Fermi arc surface state and the other can be assigned to be a Weyl point. The remaining structures are derived from the scatterings relevant to the bulk electronic states. The findings lead to further understanding of the topological electronic structure of type-II Weyl semimetal MoTe2.

Quasiparticle scattering in type-II Weyl semimetal MoTe2.

PubMed

Lin, Chun-Liang; Arafune, Ryuichi; Minamitani, Emi; Kawai, Maki; Takagi, Noriaki

2018-02-15

The electronic structure of type-II Weyl semimetal molybdenum ditelluride (MoTe 2 ) is studied by using scanning tunneling microscopy and density functional theory calculations. Through measuring energy-dependent quasiparticle interference (QPI) patterns with a cryogenic scanning tunneling microscope, several characteristic features are found in the QPI patterns. Two of them arise from the Weyl semimetal nature; one is the topological Fermi arc surface state and the other can be assigned to be a Weyl point. The remaining structures are derived from the scatterings relevant to the bulk electronic states. The findings lead to further understanding of the topological electronic structure of type-II Weyl semimetal MoTe 2 .

Sensitive Mid-Infrared Detection in Wide-Bandgap Semiconductors Using Extreme Non-Degenerate Two-Photon Absorption

DTIC Science & Technology

2011-08-07

cutting and imaging, with p- and i -GaN regions estimated to be ,1 mm in thickness36. This detector was used in photoconductive mode, with a preamplifier...D., Khoo, I . C., Salamo, G. J., Stegeman, G. I . & Van Straland, E. W. Nonlinear refraction and absorption: mechanisms and magnitudes. Adv. Opt...Am. B 9, 2065–2074 (1992). 14. Sheik- Bahae , M., Wang, J., DeSalvo, R., Hagan, D. J. & Van Styland, E. W. Measurement of nondegenerate nonlinearities

Health/education telecommunications experiment

NASA Technical Reports Server (NTRS)

Whalen, A. A.

1973-01-01

The use of ATS 6 spacecraft in a general telecommunication link for the health/education experiment demonstrates the feasibility of the small receiver-only terminal consisting of a ten foot diameter antenna located on a three-legged mount. The terminal is capable of 0 to 70 degrees elevation, course adjustment, and a plus or minus 5 degree elevation vernier adjustment. Its tuned radio frequency receiver utilizes a cavity back dipole feed and a preamplifier. The indoor unit provides further RF gain and drives a wideband limiter-discriminator.

Digital pulse processing in Mössbauer spectroscopy

NASA Astrophysics Data System (ADS)

Veiga, A.; Grunfeld, C. M.

2014-04-01

In this work we present some advances towards full digitization of the detection subsystem of a Mössbauer transmission spectrometer. We show how, using adequate instrumentation, preamplifier output of a proportional counter can be digitized with no deterioration in spectrum quality, avoiding the need of a shaping amplifier. A pipelined architecture is proposed for a digital processor, which constitutes a versatile platform for the development of pulse processing techniques. Requirements for minimization of the analog processing are considered and experimental results are presented.

Neutron Transmutation Doped (NTD) germanium thermistors for sub-mm bolometer applications

NASA Technical Reports Server (NTRS)

Haller, E. E.; Itoh, K. M.; Beeman, J. W.

1996-01-01

Recent advances in the development of neutron transmutation doped (NTD) semiconductor thermistors fabricated from natural and controlled isotopic composition germanium are reported. The near ideal doping uniformity that can be achieved with the NTD process, the device simplicity of NTD Ge thermistors and the high performance of cooled junction field effect transistor preamplifiers led to the widespread acceptance of these thermal sensors in ground-based, airborne and spaceborne radio telescopes. These features made possible the development of efficient bolometer arrays.

Bondable Fluoropolymer Film as a Water Block/Acoustic Window for Environmentally Isolating Acoustic Devices

DTIC Science & Technology

2005-11-30

titanium 2 I foil which is wrapped around a polyurethane molded acoustic 2 device and local preamplifier for the purpose of water-proofing 3 and...typical sonar signals transmitted through the 14 films 12 and 14. Therefore, the film 12 can be added to 15 traditional acoustic window designs to...4 virtually no effect on typical sonar signals yet eliminates an 5 otherwise costly and relatively thick rubber or polymer skin that 6 can be

An Analysis of a Ray Trace Experiment on the Underwater Range at Dabob Bay

DTIC Science & Technology

1975-03-01

with a local oscil- lator havIng a frequency unique to that hyIrophone. ’The outputs of these oscillators are preamplified and fed to a multiplexer...conmpared with a Eeist value given by the reference gradient plus a designated change from 5 to 30%. When the computed gradient exceeds the test value...mid profile was also performed. This comparison was designed to show the effects of using a single profile to describe the environment when the actual

Shuttle Global Positioning System (GPS) system design study

NASA Technical Reports Server (NTRS)

Nilsen, P. W.

1979-01-01

The various integration problems in the Shuttle GPS system were investigated. The analysis of the Shuttle GPS link was studied. A preamplifier was designed since the Shuttle GPS antennas must be located remotely from the receiver. Several GPS receiver architecture trade-offs were discussed. The Shuttle RF harmonics and intermode that fall within the GPS receiver bandwidth were analyzed. The GPS PN code acquisition was examined. Since the receiver clock strongly affects both GPS carrier and code acquisition performance, a clock model was developed.

Influence of an externally modulated photonic link on a microwave communications system

NASA Technical Reports Server (NTRS)

Yao, X. S.; Maleki, L.

1994-01-01

We analyze the influence of an externally modulated photonic link on the performance of a microwave communications system. From the analysis, we deduce limitations on the photocurrent, magnitude of the relaxation oscillation noise of the laser, third-order intercept point of the preamplifier, and other parameters in order for the photonic link to function according to the system specifications. Based on this, we outline a procedure for designing a photonic link that can be integrated in a system with minimal performance degradation.

Experimental Demonstration of Photon Efficient Coherent Temporal Combining for Data Rate Scaling

DTIC Science & Technology

2016-02-15

combining with pre-amplified Distribution A: Public Release. This work was sponsored by the Assistant Secretary of Defense for Research and Engineering...for -96 dBm signal with 211-1 points after block repeating and combining the waveform various number of block repeats (N). The blue dots and red...particular, Figure 5 shows constellation diagrams for the -96 dBm signal after temporal coherent combining of 4,000, 8,000, 16,000, 32,000, and 36,000 block

Circular zig-zag scan video format

DOEpatents

Peterson, C.G.; Simmons, C.M.

1992-06-09

A circular, ziz-zag scan for use with vidicon tubes is disclosed. A sine wave is generated, rectified and its fourth root extracted. The fourth root, and its inverse, are used to generate horizontal ramp and sync signals. The fourth root is also used to generate a vertical sync signal, and the vertical sync signal, along with the horizontal sync signal, are used to generate the vertical ramp signal. Cathode blanking and preamplifier clamp signals are also obtained from the vertical sync signal. 10 figs.

The 1.06 micrometer avalanche photodiode detectors with integrated circuit preamplifiers

NASA Technical Reports Server (NTRS)

Eden, R. C.

1975-01-01

The development of a complete solid state 1.06 micron optical receiver which can be used in optical communications at data rates approaching 1.5 Gb/s, or in other applications requiring sensitive, short-pulse detection, is reported. This work entailed both the development of a new type of heterojunction 3-5 semiconductor alloy avalanche photodiode and an extremely charge-sensitive wideband low-noise preamp design making use of GaAs Schottky barrier-gate field effect transistors.

Low Noise Optically Pre-amplified Lightwave Receivers and Other Applications of Fiber Optic Parametric Amplifiers

DTIC Science & Technology

2010-07-27

provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently... PERSON A. GAVRIELIDES a. REPORT UNCLAS b. ABSTRACT UNCLAS c. THIS PAGE UNCLAS 19b. TELEPHONE NUMBER (Include area code) +44 (0)1895 616205...PS) FOPAs are discussed, and the phase-squeezing behavior of PS-FOPAs is characterized in Sec V. In Sec. VI, we present measurements of the noise

Spraying Brassinolide improves Sigma Broad tolerance in foxtail millet (Setaria italica L.) through modulation of antioxidant activity and photosynthetic capacity.

PubMed

Yuan, Xiang-Yang; Zhang, Li-Guang; Huang, Lei; Yang, Hui-Jie; Zhong, Yan-Ting; Ning, Na; Wen, Yin-Yuan; Dong, Shu-Qi; Song, Xi-E; Wang, Hong-Fu; Guo, Ping-Yi

2017-09-11

To explore the role of Brassinolide (BR) in improving the tolerance of Sigma Broad in foxtail millet (Setaria italica L.), effects of 0.1 mg/L of BR foliar application 24 h before 3.37 g/ha of Sigma Broad treatment at five-leaf stage of foxtail millet on growth parameters, antioxidant enzymes, malondialdehyde (MDA), chlorophyll, net photosynthetic rate (P N ), chlorophyll fluorescence and P 700 parameters were studied 7 and 15 d after herbicide treatment, respectively. Results showed that Sigma Broad significantly decreased plant height, activities of superoxide dismutase (SOD), chlorophyll content, P N , PS II effective quantum yield (Y (II)), PS II electron transport rate (ETR (II)), photochemical quantum yield of PSI(Y (I)) and PS I electron transport rate ETR (I), but significantly increased MDA. Compared to herbicide treatment, BR dramatically increased plant height, activities of SOD, Y (II), ETR (II), Y (I) and ETR (I). This study showed BR pretreatment could improve the tolerance of Sigma Broad in foxtail millet through improving the activity of antioxidant enzymes, keeping electron transport smooth, and enhancing actual photochemical efficiency of PS II and PSI.

Efficient Simulation of Secondary Fluorescence Via NIST DTSA-II Monte Carlo.

PubMed

Ritchie, Nicholas W M

2017-06-01

Secondary fluorescence, the final term in the familiar matrix correction triumvirate Z·A·F, is the most challenging for Monte Carlo models to simulate. In fact, only two implementations of Monte Carlo models commonly used to simulate electron probe X-ray spectra can calculate secondary fluorescence-PENEPMA and NIST DTSA-II a (DTSA-II is discussed herein). These two models share many physical models but there are some important differences in the way each implements X-ray emission including secondary fluorescence. PENEPMA is based on PENELOPE, a general purpose software package for simulation of both relativistic and subrelativistic electron/positron interactions with matter. On the other hand, NIST DTSA-II was designed exclusively for simulation of X-ray spectra generated by subrelativistic electrons. NIST DTSA-II uses variance reduction techniques unsuited to general purpose code. These optimizations help NIST DTSA-II to be orders of magnitude more computationally efficient while retaining detector position sensitivity. Simulations execute in minutes rather than hours and can model differences that result from detector position. Both PENEPMA and NIST DTSA-II are capable of handling complex sample geometries and we will demonstrate that both are of similar accuracy when modeling experimental secondary fluorescence data from the literature.

Compton suppression and event triggering in a commercial data acquisition system

NASA Astrophysics Data System (ADS)

Tabor, Samuel; Caussyn, D. D.; Tripathi, Vandana; Vonmoss, J.; Liddick, S. N.

2012-10-01

A number of groups are starting to use flash digitizer systems to directly convert the preamplifier signals of high-resolution Ge detectors to a stream of digital data. Some digitizers are also equipped with software constant fraction discriminator algorithms capable of operating on the resulting digital data stream to provide timing information. Because of the dropping cost per channel of these systems, it should now be possible to also connect outputs of the Bismuth Germanate (BGO) scintillators used for Compton suppression to other digitizer inputs so that BGO logic signals can also be available in the same system. This provides the possibility to perform all the Compton suppression and multiplicity trigger logic within the digital system, thus eliminating the need for separate timing filter amplifiers (TFA), constant fraction discriminators (CFD), logic units, and lots of cables. This talk will describe the performance of such a system based on Pixie16 modules from XIA LLC with custom field programmable gate array (FPGA) programming for an array of Compton suppressed single Ge crystal and 4-crystal ``Clover'' detector array along with optional particle detectors. Initial tests of the system have produced results comparable with the current traditional system of individual electronics and peak sensing analog to digital converters. The advantages of the all digital system will be discussed.

A digital wide range neutron flux measuring system for HL-2A

NASA Astrophysics Data System (ADS)

Yuan, Chen; Wu, Jun; Yin, Zejie

2017-08-01

To achieve wide-range, high-integration, and real-time performance on the neutron flux measurement on the HL-2A tokamak, a digital neutron flux measuring (DNFM) system based on the peripheral component interconnection (PCI) eXtension for Instrumentation express (PXIe) bus was designed. This system comprises a charge-sensitive preamplifier and a field programmable gate array (FPGA)-based main electronics plug-in. The DNFM totally covers source-range and intermediate-range neutron flux measurements, and increases system integration by a large margin through joining the pulse-counting mode and Campbell mode. Meanwhile, the neutron flux estimation method based on pulse piling proportions is able to choose and switch measuring modes in accordance with current flux, and this ensures the accuracy of measurements when the neutron flux changes suddenly. It has been demonstrated by simulated signals that the DNFM enhances the full-scale measuring range up to 1.9 × 108 cm-2 s-1, with relative error below 6.1%. The DNFM has been verified to provide a high temporal sensitivity at 10 ms time intervals on a single fission chamber on HL-2A. Contributed paper, published as part of the Proceedings of the 3rd Domestic Electromagnetic Plasma Diagnostics Workshop, September 2016, Hefei, China.

Participation in the ARGUS experiment at the DORIS collider at DESY, Hamburg, Germany

DOE Office of Scientific and Technical Information (OSTI.GOV)

Darden, C.

1986-03-27

Progress reported for 1985 includes publishing final results for investigation of F mesons. Particle decays were sought including a gamma line at 9.46 GeV. One such decay was Upsilon(1S)..--> gamma..H/sup 0/. A search for fractionally charged particles is reported. The muon pair branching ratio was determined for decays of the Upsilon(2S). Six anti-deuterons were seen in a data sample of over 720,000 electron-positron annihilation events. A clear D/sup 0/ signal was seen in the K/sup +/K/sup -/ channel. Results were obtained for the radiative transitions from the Upsilon(2S) to the 1/sup 3/P states of the banti-b system. Fifteen events weremore » also seen which were interpreted to be the color suppressed decay of a B meson to J/psi. A new upper limit was set for the mass of the tau neutrino. A CAMAC booster was used to reduce dead time in the experiment. New preamplifiers raised the vertex drift chambers enough above the electromagnetic noise of the storage ring that it was no longer a problem. The performance of the inner compensation coils, storage ring, and main drift chamber are reported, as well as the time of flight, shower, and muon counters. (LEW)« less

Portable Fourier Transform Spectroscopy for Analysis of Surface Contamination and Quality Control

NASA Technical Reports Server (NTRS)

Pugel, Diane

2012-01-01

Progress has been made into adapting and enhancing a commercially available infrared spectrometer for the development of a handheld device for in-field measurements of the chemical composition of various samples of materials. The intent is to duplicate the functionality of a benchtop Fourier transform infrared spectrometer (FTIR) within the compactness of a handheld instrument with significantly improved spectral responsivity. Existing commercial technology, like the deuterated L-alanine triglycine sulfide detectors (DLATGS), is capable of sensitive in-field chemical analysis. This proposed approach compares several subsystem elements of the FTIR inside of the commercial, non-benchtop system to the commercial benchtop systems. These subsystem elements are the detector, the preamplifier and associated electronics of the detector, the interferometer, associated readout parameters, and cooling. This effort will examine these different detector subsystem elements to look for limitations in each. These limitations will be explored collaboratively with the commercial provider, and will be prioritized to meet the deliverable objectives. The tool design will be that of a handheld gun containing the IR filament source and associated optics. It will operate in a point-and-shoot manner, pointing the source and optics at the sample under test and capturing the reflected response of the material in the same handheld gun. Data will be captured via the gun and ported to a laptop.

Development of high resolution linear-cut beam position monitor for heavy-ion synchrotron of KHIMA project

NASA Astrophysics Data System (ADS)

Hwang, Ji-Gwang; Yang, Tae-Keun; Forck, Peter; Noh, Seon Yeong; Hahn, Garam; Choi, Minkyoo

2017-04-01

A beam position monitor with high precision and resolution is required to control the beam trajectory for matching to the injection orbit and acceleration in a heavy-ion synchrotron. It will be also used for measuring the beta function, tune, and chromaticity. Since the bunch length at heavy ion synchrotron is relatively long, a few meters, a boxlike device with plates of typically 20 cm length is used to enhance the signal strength and to get a precise linear dependence with respect to the beam displacement. Especially, the linear-cut beam position monitor is adopted to satisfy the position resolution of 100 μm and accuracy of 200 μm for a nominal beam intensity in the KHIMA synchrotron of ∼ 7 ×108 particles for the carbon beams and ∼ 2 ×1010 for the proton beams. In this paper, we show the electromagnetic design of the electrode and surroundings to satisfy the resolution of 100 μm, the criteria for mechanical aspect to satisfy the position accuracy of 200 μm, the measurement results by using wire test-bench, design and measurement of a high input impedance pre-amplifier, and the beam-test results with long (∼1.6 μs) electron beam in Pohang accelerator laboratory (PAL).

Compact 1 mJ fiber MOPA for space-based laser-ablation resonant ionization mass spectrometry (LARIMS)

NASA Astrophysics Data System (ADS)

Mu, Xiaodong; Crain, William; Nguyen, Can; Ionov, Pavel; Steinvurzel, Paul; Dotan, Yaniv; Karuza, Petras; Lotshaw, William; Rose, Todd; Beck, Steven; Anderson, F. Scott

2018-02-01

A 1064 nm, 1 mJ pulsed fiber MOPA module, housed in 16"x14"x2.5" package for application in a lunar and planetary in-situ surface dating instrument is demonstrated. The module is based on a three-stage MOPA with a 60 μm core tapered fiber terminal amplifier. The master oscillator and first two preamplifier stages, which generate 20 μJ pulses, are all contained on a 13"x11"x1" board. Several improvements to the electronic signal control were instrumental to the laser development, including bipolar drive of the phase modulator for SBS suppression, shaping of the seed pulse to compensate pulse steepening, and pulsed operation of the power amplifier pump to reduce spontaneous emission at low pulse repetition frequency. The packaged laser runs at a repetition rate of 10 kHz and generates 10 ns pulses at 1 mJ with a 40 GHz linewidth, an M2 1.2 beam quality, and an 18 dB polarization extinction ratio. The modular design enables seven independent lasers to be stacked in a 20"x18"x16.25" enclosure, supporting a path towards a fiber laser based LARIMS for advanced materials characterization and chronological dating in harsh and remote environments.

A home-built digital optical MRI console using high-speed serial links.

PubMed

Tang, Weinan; Wang, Weimin; Liu, Wentao; Ma, Yajun; Tang, Xin; Xiao, Liang; Gao, Jia-Hong

2015-08-01

To develop a high performance, cost-effective digital optical console for scalable multichannel MRI. The console system was implemented with flexibility and efficiency based on a modular architecture with distributed pulse sequencers. High-speed serial links were optimally utilized to interconnect the system, providing fast digital communication with a multi-gigabit data rate. The conventional analog radio frequency (RF) chain was replaced with a digital RF manipulation. The acquisition electronics were designed in close proximity to RF coils and preamplifiers, using a digital optical link to transmit the MR signal. A prototype of the console was constructed with a broad frequency range from direct current to 100 MHz. A temporal resolution of 1 μs was achieved for both the RF and gradient operations. The MR signal was digitized in the scanner room with an overall dynamic range between 16 and 24 bits and was transmitted to a master controller over a duplex optic fiber with a high data rate of 3.125 gigabits per second. High-quality phantom and human images were obtained using the prototype on both 0.36T and 1.5T clinical MRI scanners. A homemade digital optical MRI console with high-speed serial interconnection has been developed to better serve imaging research and clinical applications. © 2014 Wiley Periodicals, Inc.

Design and Characterization of a High Resolution Microfluidic Heat Flux Sensor with Thermal Modulation

PubMed Central

Nam, Sung-Ki; Kim, Jung-Kyun; Cho, Sung-Cheon; Lee, Sun-Kyu

2010-01-01

A complementary metal-oxide semiconductor-compatible process was used in the design and fabrication of a suspended membrane microfluidic heat flux sensor with a thermopile for the purpose of measuring the heat flow rate. The combination of a thirty-junction gold and nickel thermoelectric sensor with an ultralow noise preamplifier, a low pass filter, and a lock-in amplifier can yield a resolution 20 nW with a sensitivity of 461 V/W. The thermal modulation method is used to eliminate low-frequency noise from the sensor output, and various amounts of fluidic heat were applied to the sensor to investigate its suitability for microfluidic applications. For sensor design and analysis of signal output, a method of modeling and simulating electro-thermal behavior in a microfluidic heat flux sensor with an integrated electronic circuit is presented and validated. The electro-thermal domain model was constructed by using system dynamics, particularly the bond graph. The electro-thermal domain system model in which the thermal and the electrical domains are coupled expresses the heat generation of samples and converts thermal input to electrical output. The proposed electro-thermal domain system model is in good agreement with the measured output voltage response in both the transient and the steady state. PMID:22163568

PFM2: a 32 × 32 processor for X-ray diffraction imaging at FELs

NASA Astrophysics Data System (ADS)

Manghisoni, M.; Fabris, L.; Re, V.; Traversi, G.; Ratti, L.; Grassi, M.; Lodola, L.; Malcovati, P.; Vacchi, C.; Pancheri, L.; Benkechcache, M. E. A.; Dalla Betta, G.-F.; Xu, H.; Verzellesi, G.; Ronchin, S.; Boscardin, M.; Batignani, G.; Bettarini, S.; Casarosa, G.; Forti, F.; Giorgi, M.; Paladino, A.; Paoloni, E.; Rizzo, G.; Morsani, F.

2016-11-01

This work is concerned with the design of a readout chip for application to experiments at the next generation X-ray Free Electron Lasers (FEL). The ASIC, named PixFEL Matrix (PFM2), has been designed in a 65 nm CMOS technology and consists of 32 × 32 pixels. Each cell covers an area of 110 × 110 μm2 and includes a low-noise charge sensitive amplifier (CSA) with dynamic signal compression, a time-variant shaper used to process the preamplifier output signal, a 10-bit successive approximation register (SAR) analog-to-digital converter (ADC) and digital circuitry for channel control and data readout. Two different solutions for the readout channel, based on different versions of the time-variant filter, have been integrated in the chip. Both solutions can be operated in such a way to cope with the high frame rate (exceeding 1 MHz) foreseen for future X-ray FEL machines. The ASIC will be bump bonded to a slim/active edge pixel sensor to form the first demonstrator for the PixFEL X-ray imager. This work has been carried out in the frame of the PixFEL project funded by Istituto Nazionale di Fisica Nucleare (INFN), Italy.

Design of a Multi-Channel Front-End Readout ASIC With Low Noise and Large Dynamic Input Range for APD-Based PET Imaging

NASA Astrophysics Data System (ADS)

Fang, X. C.; Hu-Guo, Ch.; Ollivier-Henry, N.; Brasse, D.; Hu, Y.

2010-06-01

This paper represents the design of a low-noise, wide band multi-channel readout integrated circuit (IC) used as front end readout electronics of avalanche photo diodes (APD) dedicated to a small animal positron emission tomography (PET) system. The first ten-channel prototype chip (APD-Chip) of the analog parts has been designed and fabricated in a 0.35 μm CMOS process. Every channel of the APD_Chip includes a charge-sensitive preamplifier (CSA), a CR-(RC)2 shaper, and an analog buffer. In a channel, the CSA reads charge signals (10 bits dynamic range) from an APD array having 10 pF of capacitance per pixel. A linearized degenerated differential pair which ensures high linearity in all dynamical range is used as the high feedback resistor for preventing pile up of signals. The designed CSA has the capability of compensating automatically up to 200 nA leakage current from the detector. The CR-(RC)2 shaper filters and shapes the output signal of the CSA. An equivalent input noise charge obtained from test is 275 e -+ 10 e-/pF. In this paper the prototype is presented for both its theoretical analysis and its test results.

Front-end ASICs for high-energy astrophysics in space

NASA Astrophysics Data System (ADS)

Gevin, O.; Limousin, O.; Meuris, A.

2016-07-01

In most of embedded imaging systems for space applications, high granularity and increasing size of focal planes justify an almost systematic use of integrated circuits. . To fulfill challenging requirements for excellent spatial and energy resolution, integrated circuits must fit the sensors perfectly and interface the system such a way to optimize simultaneously noise, geometry and architecture. Moreover, very low power consumption and radiation tolerance are mandatory to envision a use onboard a payload in space. Consequently, being part of an optimized detection system for space, the integrated circuit is specifically designed for each application and becomes an Application Specific Integrated Circuits (ASIC). The paper focuses on mixed analog and digital signal ASICs for spectro-imaging systems in the keVMeV energy band. The first part of the paper summarizes the main advantages conferred by the use of front-end ASICs for highenergy astrophysics instruments in space mission. Space qualification of ASICs requires the chip to be radiation hard. The paper will shortly describe some of the typical hardening techniques and give some guidelines that an ASIC designer should follow to choose the most efficient technology for his project. The first task of the front-end electronics is to convert the charge coming from the detector into a voltage. For most of the Silicon detectors (CCD, DEPFET, SDD) this is conversion happens in the detector itself. For other sensor materials, charge preamplifiers operate the conversion. The paper shortly describes the different key parameters of charge preamplifiers and the binding parameters for the design. Filtering is generally mandatory in order to increase the signal to noise ratio or to reduce the duration of the signal. After a brief review on the main noise sources, the paper reviews noise-filtering techniques that are commonly used in Integrated circuits designs. The way sensors and ASICs are interconnected together plays a major role in the noise performances of the detection systems. The geometry of a sensor is therefore critical and drives the ASIC design. The second part of the paper takes the geometry of the detector as a story line to explore different kinds of ASIC structures and architectures. From the simple single-channel ASIC for CCDs to the most advanced 3D ASIC prototypes used to build dead-zone free imaging systems, the paper reports on different families of circuits for spectro-imaging systems. It emphasizes a variety of designer choices, all around the word, in different space missions.

Σ-Δ modulator for a programmable gain, low-power, high-linearity automotive sensor interface

NASA Astrophysics Data System (ADS)

de la Rosa, Jose M.; Medeiro, Fernando; Perez-Verdu, Belen; del Rio, Rocio; Rodriguez-Vazquez, Angel

2003-04-01

Smart sensors play a critical role in modern automotive electronic systems, covering a wide range of data capturing functions and operating under adverse environmental conditions - temperature range of [-40¦C,175¦C]. In such sensors, the signal provided by transducers is composed of an offset voltage, which depends on the manufacturing process, and a low-frequency signal carrying the information. In practice, the offset voltage is subject to temperature variations, thus causing a shifting of the signal range to be measured. Therefore, the measuring circuit driving the sensor, normally formed by a low-noise preamplifier and an Analog-to-Digital Converter (ADC), must accommodate the complete range of possible offsets and real signals. In this scenario, the use of ADCs based on Sigma-Delta Modulators (SDMs) is convenient for several reasons. On the one hand, the noise-shaping performed by SDMs allows to achieve high resolution (16-17bits), in the band of interest (10-20kHz), with less power consumption than full Nyquist ADCs. On the other hand, the action of feedback renders SDMs very linear, and high-linearity is a must for automotive applications. Last but not least, the robustness of SDMs with respect to circuit imperfections make them suitable to include programmable gain without significant performance degradation. This feature allows to accommodate the complete range of possible offsets and information signals in a sensor interface with relaxed specifications for the preamplifier circuitry. This paper describes the design and implementation of a third-order cascade (2-1) SDM with programmable gain in a 0.35mm CMOS technology - the type of technology commonly employed for automotive applications (deep submicron is mostly employed for telecom). It is capable of handling signals up to 20-kHz bandwidth with 17-bit resolution. The programmable gain is implemented by a capacitor array whose unitary capacitors are connected or disconnected depending on the value of the selected gain. In order to relax the amplifier dynamics requirements as the modulator gain varies, switchable capacitor arrays have been used for all the capacitors in the first integrator. The design of the modulator building blocks is based upon a top-down CAD methodology which combines simulation and statistical optimization at different levels of the modulator hierarchy. As a result, a dynamic range equal to 105 dB is obtained for all cases of the modulator gain, which corresponds to 17 bit resolution.

Synthesis, spectroscopic, thermal and anticancer studies of metal-antibiotic chelations: Ca(II), Fe(III), Pd(II) and Au(III) chloramphenicol complexes

NASA Astrophysics Data System (ADS)

Al-Khodir, Fatima A. I.; Refat, Moamen S.

2016-09-01

Four Ca(II), Fe(III), Pd(II) and Au(III) complexes of chloramphenicol drug have been synthesized and well characterized using elemental analyses, (infrared, electronic, and 1H-NMR) spectra, magnetic susceptibility measurement, and thermal analyses. Infrared spectral data show that the chloramphenicol drug coordinated to Ca(II), Pd(II) and Au(III) metal ions through two hydroxyl groups with 1:1 or 1:2 M ratios, but Fe(III) ions chelated towards chloramphenicol drug via the oxygen and nitrogen atoms of amide group with 1:2 ratio based on presence of keto↔enol form. The X-ray powder diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) techniques were used to identify the nano-size particles of both iron(III) and gold(III) chloramphenicol complexes. The antimicrobial assessments of the chloramphenicol complexes were scanned and collected the results against of some kind of bacteria and fungi. The cytotoxic activity of the gold(III) complex was tested against the human colon carcinoma (HCT-116) and human hepatocellular carcinoma (HepG-2) tumor cell lines.

Controlled Vectorial Electron Transfer and Photoelectrochemical Applications of Layered Relay/Photosensitizer-Imprinted Au Nanoparticle Architectures on Electrodes.

PubMed

Metzger, Tzuriel S; Tel-Vered, Ran; Willner, Itamar

2016-03-23

Two configurations of molecularly imprinted bis-aniline-bridged Au nanoparticles (NPs) for the specific binding of the electron acceptor N,N'-dimethyl-4,4'-bipyridinium (MV(2+) ) and for the photosensitizer Zn(II)-protoporphyrin IX (Zn(II)-PP-IX) are assembled on electrodes, and the photoelectrochemical features of the two configurations are discussed. Configuration I includes the MV(2+) -imprinted Au NPs matrix as a base layer, on which the Zn(II)-PP-IX-imprinted Au NPs layer is deposited, while configuration II consists of a bilayer corresponding to the reversed imprinting order. Irradiation of the two electrodes in the presence of a benzoquinone/benzohydroquinone redox probe yields photocurrents of unique features: (i) Whereas configuration I yields an anodic photocurrent, the photocurrent generated by configuration II is cathodic. (ii) The photocurrents obtained upon irradiation of the imprinted electrodes are substantially higher as compared to the nonimprinted surfaces. The high photocurrents generated by the imprinted Au NPs-modified electrodes are attributed to the effective loading of the imprinted matrices with the MV(2+) and Zn(II)-PP-IX units and to the effective charge separation proceeding in the systems. The directional anodic/cathodic photocurrents are rationalized in terms of vectorial electron transfer processes dictated by the imprinting order and by the redox potentials of the photosensitizer/electron acceptor units associated with the imprinted sites in the two configurations. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pentacyanoiron(II) as an electron donor group for nonlinear optics: medium-responsive properties and comparisons with related pentaammineruthenium(II) complexes.

PubMed

Coe, Benjamin J; Harries, Josephine L; Helliwell, Madeleine; Jones, Lathe A; Asselberghs, Inge; Clays, Koen; Brunschwig, Bruce S; Harris, James A; Garín, Javier; Orduna, Jesús

2006-09-20

In this article, we describe a series of complex salts in which electron-rich {Fe(II)(CN)(5)}(3)(-) centers are coordinated to pyridyl ligands with electron-accepting N-methyl/aryl-pyridinium substituents. These compounds have been characterized by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. Molecular quadratic nonlinear optical (NLO) responses have been determined by using hyper-Rayleigh scattering (HRS) at 1064 nm, and also via Stark (electroabsorption) spectroscopic studies on the intense, visible d --> pi* metal-to-ligand charge-transfer (MLCT) bands. The relatively large static first hyperpolarizabilities, beta(0), increase markedly on moving from aqueous to methanol solutions, accompanied by large red-shifts in the MLCT transitions. Acidification of aqueous solutions allows reversible switching of the linear and NLO properties, as shown via both HRS and Stark experiments. Time-dependent density functional theory and finite field calculations using a polarizable continuum model yield relatively good agreement with the experimental results and confirm the large decrease in beta(0) on protonation. The Stark-derived beta(0) values are generally larger for related {Ru(II)(NH(3))(5)}(2+) complexes than for their {Fe(II)(CN)(5)}(3)(-) analogues, consistent with the HRS data in water. However, the HRS data in methanol show that the stronger solvatochromism of the Fe(II) complexes causes their NLO responses to surpass those of their Ru(II) counterparts upon changing the solvent medium.

Tunable Rh 2(II,II) Light Absorbers as Excited State Electron Donors and Acceptors Accessible with Red/Near-IR Irradiation

DOE PAGES

Whittemore, Tyler; Millet, Agustin; Sayre, Hannah; ...

2018-04-04

In this study, a series of dirhodium(II,II) paddlewheeel complexes of the type cis-[Rh 2(μ-DTolF) 2(μ-L) 2][BF 4] 2, where DTolF = N,N'-di(p-tolyl)formamidinate and L = 1,8-naphthyridine (np), 2-(pyridin-2-yl)-1,8-naphthyridine (pynp), 2-(quinolin-2-yl)-1,8-naphthyridine (qnnp), and 2-(1,8-naphthyridin-2-yl)quinoxaline (qxnp), were synthesized and characterized. These molecules feature new tridentate ligands that concomitantly bridge the dirhodium core and cap the axial positions. The complexes absorb light strongly throughout the ultraviolet/visible range and into the near-infrared region and exhibit relatively long-lived triplet excited-state lifetimes. Both the singlet and triplet excited states exhibit metal/ligand-to-ligand charge transfer (ML-LCT) in nature as determined by transient absorption spectroscopy and spectroelectrochemistry measurements. Whenmore » irradiated with low-energy light, these black dyes are capable of undergoing reversible bimolecular electron transfer both to the electron acceptor methyl viologen and from the electron donor p-phenylenediamine. Photoinduced charge transfer in the latter was inaccessible with previous Rh 2(II,II) complexes. Finally, these results underscore the fact that the excited state of this class of molecules can be readily tuned for electron-transfer reactions upon simple synthetic modification and highlight their potential as excellent candidates for p- and n-type semiconductor applications and for improved harvesting of low-energy light to drive useful photochemical reactions.« less

Tunable Rh 2(II,II) Light Absorbers as Excited State Electron Donors and Acceptors Accessible with Red/Near-IR Irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whittemore, Tyler; Millet, Agustin; Sayre, Hannah

In this study, a series of dirhodium(II,II) paddlewheeel complexes of the type cis-[Rh 2(μ-DTolF) 2(μ-L) 2][BF 4] 2, where DTolF = N,N'-di(p-tolyl)formamidinate and L = 1,8-naphthyridine (np), 2-(pyridin-2-yl)-1,8-naphthyridine (pynp), 2-(quinolin-2-yl)-1,8-naphthyridine (qnnp), and 2-(1,8-naphthyridin-2-yl)quinoxaline (qxnp), were synthesized and characterized. These molecules feature new tridentate ligands that concomitantly bridge the dirhodium core and cap the axial positions. The complexes absorb light strongly throughout the ultraviolet/visible range and into the near-infrared region and exhibit relatively long-lived triplet excited-state lifetimes. Both the singlet and triplet excited states exhibit metal/ligand-to-ligand charge transfer (ML-LCT) in nature as determined by transient absorption spectroscopy and spectroelectrochemistry measurements. Whenmore » irradiated with low-energy light, these black dyes are capable of undergoing reversible bimolecular electron transfer both to the electron acceptor methyl viologen and from the electron donor p-phenylenediamine. Photoinduced charge transfer in the latter was inaccessible with previous Rh 2(II,II) complexes. Finally, these results underscore the fact that the excited state of this class of molecules can be readily tuned for electron-transfer reactions upon simple synthetic modification and highlight their potential as excellent candidates for p- and n-type semiconductor applications and for improved harvesting of low-energy light to drive useful photochemical reactions.« less

Gas phase reactions of doubly charged alkaline earth and transition metal(II)-ligand complexes generated by electrospray ionization

NASA Astrophysics Data System (ADS)

Kohler, Martin; Leary, Julie A.

1997-03-01

Doubly charged metal(II)-complexes of [alpha] 1-3, [alpha] 1-6 mannotriose and the conserved trimannosyl core pentasaccharide as well as doubly charged complexes of Co(II), Mn(II), Ca(II) and Sr(II) with acetonitrile generated by electrospray ionization were studied by low energy collision induced dissociation (CID). Two main fragmentation pathways were observed for the metal(II)-oligosaccharide complexes. Regardless of the coordinating metal, loss of a neutral dehydrohexose residue (162 Da) from the doubly charged precursor ion is observed, forming a doubly charged product ion. However, if the oligosaccharide is coordinated to Co(II) or Mn(II), loss of a dehydroxyhexose cation is also observed. Investigation of the low mass region of the mass spectra of the metal coordinated oligosaccharides revealed intense signals corresponding to [metal(II) + (CH3CN)n2+ (where n = 1-6) species which were being formed by the metal(II) ions and the acetonitrile present in the sample. Analysis of these metal(II)-acetonitrile complexes provided further insight into the processes occurring upon low energy CID of doubly charged metal complexes. The metal(II)-acetonitrile system showed neutral loss and ligand cleavage as observed with the oligosaccharide complexes, as well as a series of six different dissociation mechanisms, most notable among them reduction from [metal(II) + (CH3CN)n2+ to the bare [metal(I)]+ species by electron transfer. Depending on the metal and collision gas chosen, one observes electron transfer from the ligand to the metal, electron transfer from the collision gas to the metal, proton transfer between ligands, heterolytic cleavage of the ligands, reactive collisions and loss of neutral ligands.

JUNGFRAU 0.2: prototype characterization of a gain-switching, high dynamic range imaging system for photon science at SwissFEL and synchrotrons

NASA Astrophysics Data System (ADS)

Jungmann-Smith, J. H.; Bergamaschi, A.; Cartier, S.; Dinapoli, R.; Greiffenberg, D.; Johnson, I.; Maliakal, D.; Mezza, D.; Mozzanica, A.; Ruder, Ch; Schaedler, L.; Schmitt, B.; Shi, X.; Tinti, G.

2014-12-01

JUNGFRAU (adJUstiNg Gain detector FoR the Aramis User station) is a two-dimensional pixel detector for photon science applications at free electron lasers and synchrotron light sources. It is developed for the SwissFEL currently under construction at the Paul Scherrer Institute, Switzerland. Characteristics of this application-specific integrating circuit readout chip include single photon sensitivity and low noise over a dynamic range of over four orders of magnitude of photon input signal. These characteristics are achieved by a three-fold gain-switching preamplifier in each pixel, which automatically adjusts its gain to the amount of charge deposited on the pixel. The final JUNGFRAU chip comprises 256 × 256 pixels of 75 × 75 μm2 each. Arrays of 2 × 4 chips are bump-bonded to monolithic detector modules of about 4 × 8 cm2. Multi-module systems up to 16 Mpixels are planned for the end stations at SwissFEL. A readout rate in excess of 2 kHz is anticipated, which serves the readout requirements of SwissFEL and enables high count rate synchrotron experiments with a linear count rate capability of > 20 MHz/pixel. Promising characterization results from a 3.6 × 3.6 mm2 prototype (JUNGFRAU 0.2) with fluorescence X-ray, infrared laser and synchrotron irradiation are shown. The results include an electronic noise as low as 100 electrons root-mean-square, which enables single photon detection down to X-ray energies of about 2 keV. Noise below the Poisson fluctuation of the photon number and a linearity error of the pixel response of about 1% are demonstrated. First imaging experiments successfully show automatic gain switching. The edge spread function of the imaging system proves to be comparable in quality to single photon counting hybrid pixel detectors.

New Detector Developments for Future UV Space Missions

NASA Astrophysics Data System (ADS)

Werner, Klaus; Kappelmann, Norbert

Ultraviolet (UV) astronomy is facing “dark ages”: After the shutdown of the Hubble Space Tele-scope only the WSO/UV mission will be operable in the UV wavelength region with efficient instruments. Improved optics and detectors are necessary for future successor missions to tackle new scientific goals. This drives our development of microchannel plate (MCP) UV-detectors with high quantum efficiency, high spatial resolution and low-power readout electronics. To enhance the quantum efficiency and the lifetime of the MCP detectors we are developing new cathodes and new anodes for these detectors. To achieve high quantum efficiency, we will use caesium-activated gallium nitride as semitransparent photocathodes with a much higher efficiency than default CsI/CsTe cathodes in this wavelength range. The new anodes will be cross-strip anodes with 64 horizontal and 64 vertical electrodes. This type of anode requires a lower gain and leads to an increased lifetime of the detector, compared to MCP detectors with other anode types. The heart of the new developed front-end-electronic for such type of anode is the so called “BEETLE chip”, which was designed by the MPI für Kernphysik Heidelberg for the LHCb ex-periment at CERN. This chip provides 128 input channels with charge-sensitive preamplifiers and shapers. Our design of the complete front-end readout electronics enables a total power con-sumption of less than 10 W. The MCP detector is intrinsically solar blind, single photon counting and has a very low read-out noise. To qualify this new type of detectors we are presently planning to build a small UV telescope for the usage on the German Technology Experimental Carrier (TET). Furthermore we are involved in the new German initiative for a Public Telescope, a space telescope equipped with an 80 cm mirror. One of the main instruments will be a high-resolution UV-Echelle Spectrograph that will be built by the University of Tübingen. The launch of this mission is scheduled for 2017.

Experimental aspects in acquisition of wide bandwidth solid-state MAS NMR spectra of low-γ nuclei with different opportunities on two commercial NMR spectrometers

NASA Astrophysics Data System (ADS)

Jakobsen, Hans J.; Bildsøe, Henrik; Gan, Zhehong; Brey, William W.

2011-08-01

The acquisition and different appearances observed for wide bandwidth solid-state MAS NMR spectra of low-γ nuclei, using 14N as an illustrative nucleus and employing two different commercial spectrometers (Varian, 14.1 T and Bruker, 19.6 T), have been compared/evaluated and optimized from an experimental NMR and an electronic engineering point of view, to account for the huge differences in these spectra. The large differences in their spectral appearances, employing the recommended/standard experimental set-up for the two different spectrometers, are shown to be associated with quite large differences in the electronic design of the two types of preamplifiers, which are connected to their respective probes through a 50 Ω cable, and are here completely accounted for. This has led to different opportunities for optimum performances in the acquisition of nearly ideal wide bandwidth spectra for low-γ nuclei on the two spectrometers by careful evaluation of the length for the 50 Ω probe-to-preamp cable for the Varian system and appropriate changes to the bandwidth ( Q) of the NMR probe used on the Bruker spectrometer. Earlier, we reported quite distorted spectra obtained with Varian Unity INOVA spectrometers (at 11.4 and 14.1 T) in several exploratory wide bandwidth 14N MAS NMR studies of inorganic nitrates and amino acids. These spectra have now been compared/evaluated with fully analyzed 14N MAS spectra correspondingly acquired at 19.6 T on a Bruker spectrometer. It is shown that our upgraded version of the STARS simulation/iterative-fitting software is capable of providing identical sets for the molecular spectral parameters and corresponding fits to the experimental spectra, which fully agree with the electronic measurements, despite the highly different appearances for the MAS NMR spectra acquired on the Varian and Bruker spectrometers.

Integrated low noise low power interface for neural bio-potentials recording and conditioning

NASA Astrophysics Data System (ADS)

Bottino, Emanuele; Martinoia, Sergio; Valle, Maurizio

2005-06-01

The recent progress in both neurobiology and microelectronics suggests the creation of new, powerful tools to investigate the basic mechanisms of brain functionality. In particular, a lot of efforts are spent by scientific community to define new frameworks devoted to the analysis of in-vitro cultured neurons. One possible approach is recording their spiking activity to monitor the coordinated cellular behaviour and get insights about neural plasticity. Due to the nature of neurons action-potentials, when considering the design of an integrated microelectronic-based recording system, a number of problems arise. First, one would desire to have a high number of recording sites (i.e. several hundreds): this poses constraints on silicon area and power consumption. In this regard, our aim is to integrate-through on-chip post-processing techniques-hundreds of bio-compatible microsensors together with CMOS standard-process low-power (i.e. some tenths of uW per channel) conditioning electronics. Each recording channel is provided with sampling electronics to insure synchronous recording so that, for example, cross-correlation between signals coming from different sites can be performed. Extra-cellular potentials are in the range of [50-150] uV, so a comparison in terms of noise-efficiency was carried out among different architectures and very low-noise pre-amplification electronics (i.e. less than 5 uVrms) was designed. As spikes measurements are made with respect to the voltage of a reference electrode, we opted for an AC-coupled differential-input preamplifier provided with band-pass filtering capability. To achieve this, we implemented large time-constant (up to seconds) integrated components in the preamp feedback path. Thus, we got rid also of random slow-drifting DC-offsets and common mode signals. The paper will present our achievements in the design and implementation of a fully integrated bio-abio interface to record neural spiking activity. In particular, preliminary results will be reported.

Reversible double oxidation and protonation of the non-innocent bridge in a nickel(II) salophen complex.

PubMed

de Bellefeuille, David; Askari, Mohammad S; Lassalle-Kaiser, Benedikt; Journaux, Yves; Aukauloo, Ally; Orio, Maylis; Thomas, Fabrice; Ottenwaelder, Xavier

2012-12-03

Substitution on the aromatic bridge of a nickel(II) salophen complex with electron-donating dimethylamino substituents creates a ligand with three stable, easily and reversibly accessible oxidation states. The one-electron-oxidized product is characterized as a nickel(II) radical complex with the radical bore by the central substituted aromatic ring, in contrast to other nickel(II) salen or salophen complexes that oxidize on the phenolate moieties. The doubly oxidized product, a singlet species, is best described as having an iminobenzoquinone bridge with a vinylogous distribution of bond lengths between the dimethylamino substituents. Protonation of the dimethylamino substituents inhibits these redox processes on the time scale of cyclovoltammetry, but electrolysis and chemical oxidation are consistent with deprotonation occurring concomitantly with electron transfer to yield the mono- and dioxidized species described above.

Effect of amino acids on the interaction between cobalamin(II) and dehydroascorbic acid

NASA Astrophysics Data System (ADS)

Dereven'kov, I. A.; Thi, Thu Thuy Bui; Salnikov, D. S.; Makarov, S. V.

2016-03-01

The kinetics of the reaction between one-electron-reduced cobalamin (cobalamin(II), Cb(II)) and the two-electron-oxidized form of vitamin C (dehydroascorbic acid, DHA) with amino acids in an acidic medium is studied by conventional UV-Vis spectroscopy. It is shown that the oxidation of Cbl(II) by dehydroascorbic acid proceeds only in the presence of sulfur-containing amino acids (cysteine, acetylcysteine). A proposed reaction mechanism includes the step of amino acid coordination on the Co(II)-center through the sulfur atom, along with that of the interaction between this complex and DHA molecules, which results in the formation of ascorbyl radical and the corresponding Co(III) thiolate complex.

Spectroscopic Investigations of Catalase Compound II: Characterization of an Iron(IV) Hydroxide Intermediate in a Non-thiolate-Ligated Heme Enzyme

PubMed Central

Yosca, Timothy H.; Langston, Matthew C.; Krest, Courtney M.; Onderko, Elizabeth L.; Grove, Tyler L.; Livada, Jovan; Green, Michael T.

2018-01-01

We report on the protonation state of Helicobacter pylori catalase compound II. UV/visible, Mössbauer, and X-ray absorption spectroscopies have been used to examine the intermediate from pH 5 to 14. We have determined that HPC-II exists in an iron(IV) hydroxide state up to pH 11. Above this pH, the iron(IV) hydroxide complex transitions to a new species (pKa = 13.1) with Mössbauer parameters that are indicative of an iron(IV)-oxo intermediate. Recently, we discussed a role for an elevated compound II pKa in diminishing the compound I reduction potential. This has the effect of shifting the thermodynamic landscape toward the two-electron chemistry that is critical for catalase function. In catalase, a diminished potential would increase the selectivity for peroxide disproportionation over off-pathway one-electron chemistry, reducing the buildup of the inactive compound II state and reducing the need for energetically expensive electron donor molecules. PMID:27960340

The green hemoproteins of bovine erythrocytes. II. Spectral, ligand-binding, and electrochemical properties.

PubMed

DeFilippi, L J; Hultquist, D E

1978-05-10

The two green hemoproteins isolated from bovine erythrocytes (form I and form II) have been characterized as to spectral, electrochemical, and chemical properties. The absorption spectra of the isolated hemoproteins are typical of high spin ferric states. Reduction of the hemoproteins yields high spin ferrohemoproteins. Complexation of the ferrohemoproteins with CO and the ferrihemoproteins with cyanide yields low spin complexes, demonstrating the presence of an exchangeable weak field ligand in both the ferrous and ferric states of the hemoproteins. The differences in position and intensity of the absorption peaks of the visible spectra allow the two forms to be distinguished from one another. The midpoint potential of forms I and II were found to be +0.075 and +0.019 V, respectively, at pH 6.4 and +0.038 and -0.005 V, respectively, at pH 7.0. This is consistent with the gaining of 1 proton/electron during the reduction. The Nernst plot reveals an unusual 0.5-electron transfer, whereas a quantitative titration demonstrates a 1-electron transfer. Form I binds cyanide more tightly than form II (KD of 84 and 252 micrometer, respectively). The observed spectral, electrochemical, and ligand-binding differences between forms I and II can be explained in terms of a greater electron-withdrawing ability of the side chains of the heme of form I relative to the heme of form II.

Mn(II) Oxidation by the Multicopper Oxidase Complex Mnx: A Coordinated Two-Stage Mn(II)/(III) and Mn(III)/(IV) Mechanism.

PubMed

Soldatova, Alexandra V; Romano, Christine A; Tao, Lizhi; Stich, Troy A; Casey, William H; Britt, R David; Tebo, Bradley M; Spiro, Thomas G

2017-08-23

The bacterial manganese oxidase MnxG of the Mnx protein complex is unique among multicopper oxidases (MCOs) in carrying out a two-electron metal oxidation, converting Mn(II) to MnO 2 nanoparticles. The reaction occurs in two stages: Mn(II) → Mn(III) and Mn(III) → MnO 2 . In a companion study , we show that the electron transfer from Mn(II) to the low-potential type 1 Cu of MnxG requires an activation step, likely forming a hydroxide bridge at a dinuclear Mn(II) site. Here we study the second oxidation step, using pyrophosphate (PP) as a Mn(III) trap. PP chelates Mn(III) produced by the enzyme and subsequently allows it to become a substrate for the second stage of the reaction. EPR spectroscopy confirms the presence of Mn(III) bound to the enzyme. The Mn(III) oxidation step does not involve direct electron transfer to the enzyme from Mn(III), which is shown by kinetic measurements to be excluded from the Mn(II) binding site. Instead, Mn(III) is proposed to disproportionate at an adjacent polynuclear site, thereby allowing indirect oxidation to Mn(IV) and recycling of Mn(II). PP plays a multifaceted role, slowing the reaction by complexing both Mn(II) and Mn(III) in solution, and also inhibiting catalysis, likely through binding at or near the active site. An overall mechanism for Mnx-catalyzed MnO 2 production from Mn(II) is presented.

Electron transfer flavoprotein domain II orientation monitored using double electron-electron resonance between an enzymatically reduced, native FAD cofactor, and spin labels.

PubMed

Swanson, Michael A; Kathirvelu, Velavan; Majtan, Tomas; Frerman, Frank E; Eaton, Gareth R; Eaton, Sandra S

2011-03-01

Human electron transfer flavoprotein (ETF) is a soluble mitochondrial heterodimeric flavoprotein that links fatty acid β-oxidation to the main respiratory chain. The crystal structure of human ETF bound to medium chain acyl-CoA dehydrogenase indicates that the flavin adenine dinucleotide (FAD) domain (αII) is mobile, which permits more rapid electron transfer with donors and acceptors by providing closer access to the flavin and allows ETF to accept electrons from at least 10 different flavoprotein dehydrogenases. Sequence homology is high and low-angle X-ray scattering is identical for Paracoccus denitrificans (P. denitrificans) and human ETF. To characterize the orientations of the αII domain of P. denitrificans ETF, distances between enzymatically reduced FAD and spin labels in the three structural domains were measured by double electron-electron resonance (DEER) at X- and Q-bands. An FAD to spin label distance of 2.8 ± 0.15 nm for the label in the FAD-containing αII domain (A210C) agreed with estimates from the crystal structure (3.0 nm), molecular dynamics simulations (2.7 nm), and rotamer library analysis (2.8 nm). Distances between the reduced FAD and labels in αI (A43C) were between 4.0 and 4.5 ± 0.35 nm and for βIII (A111C) the distance was 4.3 ± 0.15 nm. These values were intermediate between estimates from the crystal structure of P. denitrificans ETF and a homology model based on substrate-bound human ETF. These distances suggest that the αII domain adopts orientations in solution that are intermediate between those which are observed in the crystal structures of free ETF (closed) and ETF bound to a dehydrogenase (open). Copyright © 2011 The Protein Society.

Electron impact excitation of argon in the extreme vacuum ultraviolet

NASA Technical Reports Server (NTRS)

Mentall, J. E.; Morgan, H. D.

1976-01-01

Polarization-free excitation cross sections in the extreme vacuum ultraviolet have been measured for electron impact on Ar. Observed spectral features were those lines of Ar I and Ar II which lie between 700 and 1100 A. Excitation functions were measured for the Ar I resonance line at 1048 A and the Ar II resonance line at 920 A. Peak cross sections for these two lines were found to be (39.4 plus or minus 7.9) x 10 to the -18th and (6.9 plus or minus 1.4) x 10 to the -18th, respectively. At low energies, excitation of the Ar II resonance line is dominated by an electron exchange transition.

Herschel Galactic Plane Survey of [NII] Fine Structure Emission

NASA Astrophysics Data System (ADS)

Goldsmith, Paul F.; Yıldız, Umut A.; Langer, William D.; Pineda, Jorge L.

2015-12-01

We present the first large-scale high angular resolution survey of ionized nitrogen in the Galactic Plane through emission of its two fine structure transitions ([N ii]) at 122 and 205 μm. The observations were largely obtained with the PACS instrument onboard the Herschel Space Observatory. The lines of sight were in the Galactic plane, following those of the Herschel OTKP project GOT C+. Both lines are reliably detected at the 10-8-10-7 Wm-2 sr-1 level over the range -60° ≤ l ≤ 60°. The rms of the intensity among the 25 PACS spaxels of a given pointing is typically less than one third of the mean intensity, showing that the emission is extended. [N ii] is produced in gas in which hydrogen is ionized, and collisional excitation is by electrons. The ratio of the two fine structure transitions provides a direct measurement of the electron density, yielding n(e) largely in the range 10-50 cm-3 with an average value of 29 cm-3 and N+ column densities 1016-1017 cm-2. [N ii] emission is highly correlated with that of [C ii], and we calculate that between 1/3 and 1/2 of the [C ii] emission is associated with the ionized gas. The relatively high electron densities indicate that the source of the [N ii] emission is not the warm ionized medium (WIM), which has electron densities more than 100 times smaller. Possible origins of the observed [N ii] include the ionized surfaces of dense atomic and molecular clouds, the extended low-density envelopes of H ii regions, and low-filling factor high-density fluctuations of the WIM.

Simultaneous Femtosecond X-ray Spectroscopy and Diffraction of Photosystem II at Room Temperature

PubMed Central

Kern, Jan; Alonso-Mori, Roberto; Tran, Rosalie; Hattne, Johan; Gildea, Richard J.; Echols, Nathaniel; Glöckner, Carina; Hellmich, Julia; Laksmono, Hartawan; Sierra, Raymond G.; Lassalle-Kaiser, Benedikt; Koroidov, Sergey; Lampe, Alyssa; Han, Guangye; Gul, Sheraz; DiFiore, Dörte; Milathianaki, Despina; Fry, Alan R.; Miahnahri, Alan; Schafer, Donald W.; Messerschmidt, Marc; Seibert, M. Marvin; Koglin, Jason E.; Sokaras, Dimosthenis; Weng, Tsu-Chien; Sellberg, Jonas; Latimer, Matthew J.; Grosse-Kunstleve, Ralf W.; Zwart, Petrus H.; White, William E.; Glatzel, Pieter; Adams, Paul D.; Bogan, Michael J.; Williams, Garth J.; Boutet, Sébastien; Messinger, Johannes; Zouni, Athina; Sauter, Nicholas K.; Yachandra, Vittal K.; Bergmann, Uwe; Yano, Junko

2013-01-01

Intense femtosecond X-ray pulses produced at the Linac Coherent Light Source (LCLS) were used for simultaneous X-ray diffraction (XRD) and X-ray emission spectroscopy (XES) of microcrystals of Photosystem II (PS II) at room temperature. This method probes the overall protein structure and the electronic structure of the Mn4CaO5 cluster in the oxygen-evolving complex of PS II. XRD data are presented from both the dark state (S1) and the first illuminated state (S2) of PS II. Our simultaneous XRD/XES study shows that the PS II crystals are intact during our measurements at the LCLS, not only with respect to the structure of PS II, but also with regard to the electronic structure of the highly radiation sensitive Mn4CaO5 cluster, opening new directions for future dynamics studies. PMID:23413188

Simultaneous femtosecond X-ray spectroscopy and diffraction of photosystem II at room temperature.

PubMed

Kern, Jan; Alonso-Mori, Roberto; Tran, Rosalie; Hattne, Johan; Gildea, Richard J; Echols, Nathaniel; Glöckner, Carina; Hellmich, Julia; Laksmono, Hartawan; Sierra, Raymond G; Lassalle-Kaiser, Benedikt; Koroidov, Sergey; Lampe, Alyssa; Han, Guangye; Gul, Sheraz; Difiore, Dörte; Milathianaki, Despina; Fry, Alan R; Miahnahri, Alan; Schafer, Donald W; Messerschmidt, Marc; Seibert, M Marvin; Koglin, Jason E; Sokaras, Dimosthenis; Weng, Tsu-Chien; Sellberg, Jonas; Latimer, Matthew J; Grosse-Kunstleve, Ralf W; Zwart, Petrus H; White, William E; Glatzel, Pieter; Adams, Paul D; Bogan, Michael J; Williams, Garth J; Boutet, Sébastien; Messinger, Johannes; Zouni, Athina; Sauter, Nicholas K; Yachandra, Vittal K; Bergmann, Uwe; Yano, Junko

2013-04-26

Intense femtosecond x-ray pulses produced at the Linac Coherent Light Source (LCLS) were used for simultaneous x-ray diffraction (XRD) and x-ray emission spectroscopy (XES) of microcrystals of photosystem II (PS II) at room temperature. This method probes the overall protein structure and the electronic structure of the Mn4CaO5 cluster in the oxygen-evolving complex of PS II. XRD data are presented from both the dark state (S1) and the first illuminated state (S2) of PS II. Our simultaneous XRD-XES study shows that the PS II crystals are intact during our measurements at the LCLS, not only with respect to the structure of PS II, but also with regard to the electronic structure of the highly radiation-sensitive Mn4CaO5 cluster, opening new directions for future dynamics studies.

Palladium and gold removal and recovery from precious metal solutions and electronic scrap leachates by Desulfovibrio desulfuricans.

PubMed

Creamer, Neil J; Baxter-Plant, Victoria S; Henderson, John; Potter, M; Macaskie, Lynne E

2006-09-01

Biomass of Desulfovibrio desulfuricans was used to recover Au(III) as Au(0) from test solutions and from waste electronic scrap leachate. Au(0) was precipitated extracellularly by a different mechanism from the biodeposition of Pd(0). The presence of Cu(2+) ( approximately 2000 mg/l) in the leachate inhibited the hydrogenase-mediated removal of Pd(II) but pre-palladisation of the cells in the absence of added Cu(2+) facilitated removal of Pd(II) from the leachate and more than 95% of the Pd(II) was removed autocatalytically from a test solution supplemented with Cu(II) and Pd(II). Metal recovery was demonstrated in a gas-lift electrobioreactor with electrochemically generated hydrogen, followed by precipitation of recovered metal under gravity. A 3-stage bioseparation process for the recovery of Au(III), Pd(II) and Cu(II) is proposed.

Research and development of a high-performance differential-hybrid charge sensitive preamplifier.

PubMed

Zeng, Guoqiang; Hu, Chuanhao; Wei, Shilong; Yang, Jian; Li, Qiang; Ge, Liangquan; Tan, Chengjun

2017-02-01

A differential-hybrid charge sensitive preamplifier (CSP) was designed by taking a monolithic dual N-Channel Junction Field-effect Transistor (JFET) and a high-speed, low-noise, operational amplifier as the core parts. Input-stage of the circuit employs low-noise differential dual JFET, which ensures high input impedance and low noise. The differential dual transistor makes the quiescent point of the first-stage differential output stable, which is convenient for connecting with the post stage high-speed operational amplifier. Broadband could be amplified by connecting to the double differential dual transistors through the folded cascode-bootstrap. The amplifying circuit which replaces the interstage and post stage discrete components of a traditional CSP with integrated operational amplifier is simpler and more reliable. It simplifies the design of the quiescent point, gives full play to advantages of releasing large open-loop gain, and improves charge-voltage conversion gain stability. Particularly, the charge-voltage conversion gain is larger under a smaller feedback capacitor, thus enabling to gain better signal-noise ratio. The designed CSP was tested, reporting 3.3×10 13 V/C charge sensitivity, about 90ns rise time of signals, 35:1 signal-noise ratio to gamma-rays of 137 Cs (662keV) and a 0.023 fC/pF noise slope. Gamma-rays of 241 Am (59.5keV) were measured by the BPX66 detector and the designed CSP under room temperature, providing 1.97% energy resolution. Copyright © 2016 Elsevier Ltd. All rights reserved.

A CMOS power-efficient low-noise current-mode front-end amplifier for neural signal recording.

PubMed

Wu, Chung-Yu; Chen, Wei-Ming; Kuo, Liang-Ting

2013-04-01

In this paper, a new current-mode front-end amplifier (CMFEA) for neural signal recording systems is proposed. In the proposed CMFEA, a current-mode preamplifier with an active feedback loop operated at very low frequency is designed as the first gain stage to bypass any dc offset current generated by the electrode-tissue interface and to achieve a low high-pass cutoff frequency below 0.5 Hz. No reset signal or ultra-large pseudo resistor is required. The current-mode preamplifier has low dc operation current to enhance low-noise performance and decrease power consumption. A programmable current gain stage is adopted to provide adjustable gain for adaptive signal scaling. A following current-mode filter is designed to adjust the low-pass cutoff frequency for different neural signals. The proposed CMFEA is designed and fabricated in 0.18-μm CMOS technology and the area of the core circuit is 0.076 mm(2). The measured high-pass cutoff frequency is as low as 0.3 Hz and the low-pass cutoff frequency is adjustable from 1 kHz to 10 kHz. The measured maximum current gain is 55.9 dB. The measured input-referred current noise density is 153 fA /√Hz , and the power consumption is 13 μW at 1-V power supply. The fabricated CMFEA has been successfully applied to the animal test for recording the seizure ECoG of Long-Evan rats.

Development of cryogenic Yb:YAG ceramics amplifier for over 100 J DPSSL

NASA Astrophysics Data System (ADS)

Sekine, T.; Takeuchi, Y.; Kurita, T.; Hatano, Y.; Muramatsu, Y.; Mizuta, Y.; Kabeya, Y.; Tamaoki, Y.; Kato, Y.

2017-02-01

A high gain cryogenic Yb:YAG ceramics laser amplifier for a high energy laser amplification system has been developed. The laser system consists of a fiber oscillator and two stage LD pumped cryogenic Yb:YAG ceramic amplifiers. The preamplifier stage has a 5-pass laser amplifier head and the main amplifier stage has a 2-pass laser amplifier head, respectively. The preamplifier obtained an average stored energy density of 0.836 J/cc and small-signal gain (SSG) of 60 with 33 J of stored energy. Then about 1 μJ of input energy from the oscillator was amplified to 3.6 J. The main amplifier head had four pumping LD modules which irradiated the Yb:YAG ceramics directly. This original angular pumping scheme ideally increases irradiation intensity and homogenizes irradiation pattern on the Yb:YAG ceramics due to superposition effect of all of the LD modules. A maximum peak power of over 100 kW was generated by one LD module. When the output energy of the LD modules was 450 J, a 20 of SSG at single pass was obtained. Stored energy density was evaluated to 0.429 J/cc when 148 J energy was stored in 346 cc of Yb:YAG ceramics. As a result, a 55-J output energy with 10 ns pulse duration was demonstrated at a pumping energy of 450 J. The optical-tooptical conversion efficiency which includes transmissivity of the LD modules was 12 %. The extraction efficiency was estimated to 37%.

Implementation of a preamplifier-amplifier system for radiation detectors used in Mössbauer spectroscopy

NASA Astrophysics Data System (ADS)

Velásquez, A. A.; Arroyave, M.

2014-01-01

We report the assembly and testing of a preamplification and amplification system for pulses produced by gaseous radiation detectors commonly used in Mössbauer spectroscopy. The system is composed by a pair of commercial integrated circuits A203 and A206, which operate as charge sensitive preamplifier-shaping amplifier and linear amplifier-low level discriminator, respectively. The integrated circuits were interconnected in the unipolar output mode and placed inside a metallic shielding, which prevents noise amplification for a suitable signal-noise ratio. The system was tested by irradiating a proportional counter LND-45431 with characteristic X rays of 6.3 keV and gamma rays of 14.4 keV emitted by a Mössbauer radioactive source of 57Co (Rh). Unipolar pulses with Gaussian profile were obtained at the output of the linear amplifier, whose amplitudes were close to 0.4 V for 6.3 keV X rays and 1.4 V for 14.4 keV gamma rays. Pulse height spectra showed that the system allows a satisfactory identification of the X-rays and gamma rays emitted by the 57Co source, giving the possibility to make a good selection of the 14.4 keV peak for having a suitable signal-noise ratio in the Mössbauer spectra. Absorption percentages of 14 % were found by taking the Mössbauer spectra of a natural iron absorber. The assembly and tests of the system are presented through this paper.

Statistical characterization of voltage-biased SQUIDs with weakly damped junctions

NASA Astrophysics Data System (ADS)

Liu, Chao; Zhang, Yi; Mück, Michael; Zhang, Shulin; Krause, Hans-Joachim; Braginski, Alex I.; Zhang, Guofeng; Wang, Yongliang; Kong, Xiangyan; Xie, Xiaoming; Offenhäusser, Andreas; Jiang, Mianheng

2013-06-01

Recently, it has been shown that voltage-biased readout of SQUIDs with weakly damped junctions (large Stewart-McCumber parameter βc, due to high shunt resistance) is useful for suppression of preamplifier noise. We experimentally studied the characteristics of 53 planar niobium-SQUID magnetometers with junction shunt resistors RJ nominally of 30 Ω fabricated on 5 × 5 mm2 chips. The field-to-flux transfer coefficient ∂B/∂Φ of the magnetometers was 1.5 nT/Φ0, with a SQUID loop inductance Ls of about 350 pH. The distributions of important SQUID parameters, such as the current swing Iswing, the dynamic resistance Rd, and the flux-to-voltage transfer coefficient ∂V/∂Φ, are given. Nearly all the SQUIDs could be stably operated in the voltage bias mode and their ∂V/∂Φ reached a large mean value of 380 μV/Φ0. In this case, the SQUIDs can be read out directly by a commercial operational amplifier without any additional means to suppress preamplifier noise. The mean flux noise of the SQUIDs was found to be 4.5 μΦ0 Hz-1/2, corresponding to a field resolution of 7 fT Hz-1/2. To demonstrate the applicability of these SQUIDs in the direct readout scheme, a simple four-channel SQUID gradiometer system was set up to perform magnetocardiography and magnetoencephalography measurements in a magnetically shielded room.

Cross-Talk Limits of Highly Segmented Semiconductor Detectors

NASA Astrophysics Data System (ADS)

Pullia, Alberto; Weisshaar, Dirk; Zocca, Francesca; Bazzacco, Dino

2011-06-01

Cross-talk limits of monolithic highly-segmented semiconductor detectors for high-resolution X-gamma spectrometry are investigated. Cross-talk causes false signal components yielding amplitude losses and fold-dependent shifts of the spectral lines, which partially spoil the spectroscopic performance of the detector. Two complementary electrical models are developed, which describe quantitatively the inter-channel cross-talk of monolithic segmented detectors whose electrodes are read out by charge-sensitive preamplifiers. The first is here designated as Cross-Capacitance (CC) model, the second as Split-Charge (SC) model. The CC model builds around the parasitic capacitances Cij linking the preamplifier outputs and the neighbor channel inputs. The SC model builds around the finite-value of the decoupling capacitance CC used to read out the high-voltage detector electrode. The key parameters of the models are individuated and ideas are shown to minimize their impact. Using a quasi-coaxial germanium segmented detector it is found that the SC cross-talk becomes negligible for decoupling capacitances larger than 1 nF, where instead the CC cross-talk tends to dominate. The residual cross-talk may be reduced by minimization of stray capacitances Cij, through a careful design of the layout of the Printed Circuit Board (PCB) where the input transistors are mounted. Cij can be made as low as 5 fF, but it is shown that even in such case the impact of the CC cross-talk on the detector performance is not negligible. Finally, an algorithm for cross-talk correction is presented and elaborated.

78 FR 37998 - Electronic One Touch Bingo System

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-25

... decision regarding the classification of server based electronic bingo system games that can be played... Class II or Class III game. DATES: The agency must receive comments on or before August 26, 2013... from the regulated community regarding the status of one touch bingo as a Class II or a Class III game...

Industrial Education. Electricity/Electronics Curriculum Guide, Phase II. Instructional Modules, Level II.

ERIC Educational Resources Information Center

Lillo, Robert E.; Soffiotto, Nicholas S.

Designed for students in the ninth grade, this electricity/electronics curriculum guide contains instructional modules for twenty-four units of instruction. Among the modules included are (1) introduction to the world of electricity, (2) electrical safety, (3) the electrical team, (4) resistance and resistors, (5) electric lamps and heating…

The rapidly metabolized 32,000-dalton polypeptide of the chloroplast is the "proteinaceous shield" regulating photosystem II electron transport and mediating diuron herbicide sensitivity.

PubMed Central

Mattoo, A K; Pick, U; Hoffman-Falk, H; Edelman, M

1981-01-01

Mild trypsin treatment of Spirodela oligorrhiza thylakoid membranes leads to partial digestion of the rapidly metabolized, surface-exposed, 32,000-dalton protein. Under these conditions, photoreduction of ferricyanide becomes insensitive to diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea], an inhibitor of photosystem II electron transport. Preincubation of thylakoids with diuron leads to a conformational change in the 32,000-dalton protein, modifying its trypsin digestion and preventing expression of diuron insensitivity. Finally, light affects the susceptibility of the 32,000-dalton protein to digestion by trypsin. In other experiments, thylakoids specifically depleted in the 32,000-dalton protein were found to be deficient in electron transport at the reducing side of photosystem II but not at the oxidizing side or in photosystem I activities. Thus, the rapidly metabolized 32,000-dalton thylakoid protein in Spirodela chloroplasts fulfills the requirements of the hypothesized "proteinaceous shield" [Renger, G. (1976) Biochim. Biophys. Acta 440, 287-300] regulating electron flow through photosystem II and mediating diuron sensitivity. Images PMID:6940173

Metastable Defect Formation at Microvoids Identified as a Source of Light-Induced Degradation in a-Si :H

NASA Astrophysics Data System (ADS)

Fehr, M.; Schnegg, A.; Rech, B.; Astakhov, O.; Finger, F.; Bittl, R.; Teutloff, C.; Lips, K.

2014-02-01

Light-induced degradation of hydrogenated amorphous silicon (a-Si :H), known as the Staebler-Wronski effect, has been studied by time-domain pulsed electron-paramagnetic resonance. Electron-spin echo relaxation measurements in the annealed and light-soaked state revealed two types of defects (termed type I and II), which can be discerned by their electron-spin echo relaxation. Type I exhibits a monoexponential decay related to indirect flip-flop processes between dipolar coupled electron spins in defect clusters, while the phase relaxation of type II is dominated by H1 nuclear spin dynamics and is indicative for isolated spins. We propose that defects are either located at internal surfaces of microvoids (type I) or are isolated and uniformly distributed in the bulk (type II). The concentration of both defect type I and II is significantly higher in the light-soaked state compared to the annealed state. Our results indicate that in addition to isolated defects, defects on internal surfaces of microvoids play a role in light-induced degradation of device-quality a-Si :H.

On the positronium spin conversion reactions caused by some macrocyclic Co II complexes

NASA Astrophysics Data System (ADS)

Fantola-Lazzarini, Anna L.; Lazzarini, Ennio

2002-08-01

The rate constants, kCR, of ortho- into para-positronium ( o-Ps→ p-Ps) spin conversion reactions, CR, caused by the high-spin [Co IIsep] 2+, [Co IIdinosar] 2+ and [Co IIdiamsar] 2+ macrocyclic complexes and also by high-spin [Co II sen] 2+ tripod complex were measured at several temperatures. The delocalizations, β, of Co II unpaired electrons, promoted by the mentioned ligands, were determined by using the previously established correlations between kCR and the electron delocalization β of unpaired metal electrons. β is given by the ratio between the Racah inter-electronic repulsion parameters of complexes, B, and that of the free ions, B0. The β values are compared with those of the Co II complexes with en (1,2-ethanediamine), pn (1,2 propanediamine) and dien (2,2' diamino diethylamine) ligands. The kCR rate constants are also compared with those of the Ps oxidation reactions, OR, promoted by the corresponding Co III complexes. It is concluded that, unlike OR's, the CR's do not occur by formation of hepta-coordinate adducts with Ps atoms.

Electronic structural changes of Mn in the oxygen-evolving complex of photosystem II during the catalytic cycle.

PubMed

Glatzel, Pieter; Schroeder, Henning; Pushkar, Yulia; Boron, Thaddeus; Mukherjee, Shreya; Christou, George; Pecoraro, Vincent L; Messinger, Johannes; Yachandra, Vittal K; Bergmann, Uwe; Yano, Junko

2013-05-20

The oxygen-evolving complex (OEC) in photosystem II (PS II) was studied in the S0 through S3 states using 1s2p resonant inelastic X-ray scattering spectroscopy. The spectral changes of the OEC during the S-state transitions are subtle, indicating that the electrons are strongly delocalized throughout the cluster. The result suggests that, in addition to the Mn ions, ligands are also playing an important role in the redox reactions. A series of Mn(IV) coordination complexes were compared, particularly with the PS II S3 state spectrum to understand its oxidation state. We find strong variations of the electronic structure within the series of Mn(IV) model systems. The spectrum of the S3 state best resembles those of the Mn(IV) complexes Mn3(IV)Ca2 and saplnMn2(IV)(OH)2. The current result emphasizes that the assignment of formal oxidation states alone is not sufficient for understanding the detailed electronic structural changes that govern the catalytic reaction in the OEC.

Resonant excitation of high order modes in the 3.9 GHz cavity of the Linac Coherent Light Source

DOE PAGES

Lunin, A.; Khabiboulline, T.; Solyak, N.; ...

2018-02-06

Construction of the Linac Coherent Light Source II (LCLS-II) is underway for the world’s first hard x-ray free-electron laser. A central part of the LCLS-II project is a 4 GeV superconducting radio frequency electron linac that will operate in the continuous wave (cw) mode. The linac is segmented into four sections named as L0, L1, L2, and L3. Two 3.9 GHz cryomodules, each housing of eight third-harmonic cavities similar to the cavities developed for the European X-ray Free Electron Laser (XFEL), will be used in section L1 of the linac for linearizing the longitudinal beam profile. Here in this paper, we presentmore » a study of trapped high order modes (HOMs) excited by a cw electron beam in the third-harmonic cavities of the LCLS-II linac. A detailed comparison of the original XFEL design and the LCLS-II design with a modified end group is performed in order to estimate the effect of a reduced beam pipe aperture on the efficiency of HOM damping. Furthermore, we apply a statistical analysis of the eigenmode spectrum for the estimation of the probability of resonant HOM losses and influence of HOMs on beam dynamics.« less

Modeling the active site of [NiFe] hydrogenases and the [NiFeu] subsite of the C-cluster of carbon monoxide dehydrogenases: low-spin iron(II) versus high-spin iron(II).

PubMed

Weber, Katharina; Erdem, Özlen F; Bill, Eckhard; Weyhermüller, Thomas; Lubitz, Wolfgang

2014-06-16

A series of four [S2Ni(μ-S)2FeCp*Cl] compounds with different tetradentate thiolate/thioether ligands bound to the Ni(II) ion is reported (Cp* = C5Me5). The {S2Ni(μ-S)2Fe} core of these compounds resembles structural features of the active site of [NiFe] hydrogenases. Detailed analyses of the electronic structures of these compounds by Mössbauer and electron paramagnetic resonance spectroscopy, magnetic measurements, and density functional theory calculations reveal the oxidation states Ni(II) low spin and Fe(II) high spin for the metal ions. The same electronic configurations have been suggested for the Cred1 state of the C-cluster [NiFeu] subsite in carbon monoxide dehydrogenases (CODH). The Ni-Fe distance of ∼3 Å excludes a metal-metal bond between nickel and iron, which is in agreement with the computational results. Electrochemical experiments show that iron is the redox active site in these complexes, performing a reversible one-electron oxidation. The four complexes are discussed with regard to their similarities and differences both to the [NiFe] hydrogenases and the C-cluster of Ni-containing CODH.

Resonant excitation of high order modes in the 3.9 GHz cavity of the Linac Coherent Light Source

NASA Astrophysics Data System (ADS)

Lunin, A.; Khabiboulline, T.; Solyak, N.; Sukhanov, A.; Yakovlev, V.

2018-02-01

Construction of the Linac Coherent Light Source II (LCLS-II) is underway for the world's first hard x-ray free-electron laser. A central part of the LCLS-II project is a 4 GeV superconducting radio frequency electron linac that will operate in the continuous wave (cw) mode. The linac is segmented into four sections named as L 0 , L 1 , L 2 , and L 3 . Two 3.9 GHz cryomodules, each housing of eight third-harmonic cavities similar to the cavities developed for the European X-ray Free Electron Laser (XFEL), will be used in section L 1 of the linac for linearizing the longitudinal beam profile. In this paper, we present a study of trapped high order modes (HOMs) excited by a cw electron beam in the third-harmonic cavities of the LCLS-II linac. A detailed comparison of the original XFEL design and the LCLS-II design with a modified end group is performed in order to estimate the effect of a reduced beam pipe aperture on the efficiency of HOM damping. Furthermore, we apply a statistical analysis of the eigenmode spectrum for the estimation of the probability of resonant HOM losses and influence of HOMs on beam dynamics.

In-line wear monitor. Final report, July 1988-April 1989

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pieper, K.A.; Taylor, I.J.

This report describes construction and test results of an in-line monitor for critical ferrous and nonferrous metal debris in turbine engine lubrication systems. The in-line wear monitor (ILWM) uses the X-ray fluorescence principle for detecting metal debris on a continuous basis while the engine is running. The sensor portion of the system is engine mounted and contains a radioactive X-ray source, a flow cell to direct the oil across an X-ray permeable window, a proportional counter X-ray detector and its associated preamplifier and amplifier electronics. The data acquisition electronics is mounted on the airframe and contains a microprocessor based systemmore » for inputting pulses from the sensor, classifying and counting them according to energy bands, and analyzing the data and outputting metal concentration values to the engine monitoring system. The sensor portion of the system is designed to fit on a TF41 turbine engine in place of a tube between the oil tank and the oil pump. A TF41 engine monitoring system has been modified to accept the new signals from the ILWM on spare inputs so that none of the existing functions were disturbed. The ILWM has been flow tested at various flow rates, concentration levels, oil temperatures, and aerations. The wear monitor detected iron, copper, and both iron and copper together with less than 2 ppm one sigma statistical uncertainty for 30 minute count times over the 0-50 ppm range. There was no significant effect of flow rate or aeration on accuracy. The system is developed to the point that it can be tested in an actual flight environment.« less

The Zero-Degree Detector System

NASA Technical Reports Server (NTRS)

Adams, James H.; Christl, Mark J.; Howell, Leonard W.; Kouznetsov, Evgueni

2006-01-01

We will report on a detector system used for accelerator measurement of nuclear fragmentation cross sections. This system consists of two detector planes, each carrying a ring of 8 detectors. Each detector has 64 pads. These two detector planes are arranged facing each other so that the matching detector pads on each plane form a two element charged particle telescope. Each of these telescopes is capable of determining the elemental identity of nuclear fragments passing through it. The system is used to measure light fragment production in the presence of heavier fragments. We will present a detailed discussion of the 64-pad detector design, the substrate design. The front-end electronics used to read out the signals is based on a custom VLSI chip developed for the Advanced Thin Ionization Calorimeter experiment which has been flown successfully twice in Antarctica. Each of these chips has 16 channels and each channel consists of a charge-sensitive preamplifier followed by a shaping amplifier and a track-and-hold circuit. The track-and-hold circuits are connected via a multiplexer to an output line driver. This allows the held signals to be presented, one-by-one via a common data line to a analog-to-digital converter. Because the output line driver can be placed in a high input impedance state when not in use, it is possible to daisy-change many chips on the same common data line. The front-end electronics and data readout scheme will be discussed in detail. The Zero Degree Detector has been used in several accelerator experiments conducted at the NASA Space Radiation Laboratory and the Alternating Gradient Synchrotron at Brookhaven National Laboratory as well as at the HIMAC accelerator in Japan. We will show examples of data taken at these accelerator runs to demonstrate how the system works.

Optimization and application of cooled avalanche photodiodes for spectroscopic fluctuation measurements with ultra-fast charge exchange recombination spectroscopy

DOE PAGES

Truong, D. D.; Fonck, R. J.; McKee, G. R.

2016-09-23

The Ultra Fast Charge Exchange Recombination Spectroscopy (UF-CHERS) diagnostic is a highly specialized spectroscopic instrument with 2 spatial channels consisting of 8 spectral channels each and a resolution of ~0.25 nm deployed at DIII-D to measure turbulent ion temperature fluctuations. Charge exchange emissions are obtained between 528-530 nm with 1 μs time resolution to study plasma instabilities. A primary challenge of extracting fluctuation measurements from raw UF-CHERS signals is photon and electronic noise. In order to reduce dark current, the Avalanche Photodiode (APD) detectors are thermoelectrically cooled. State-of-the-art components are used for the signal amplifiers and conditioners to minimize electronicmore » noise. Due to the low incident photon power (≤ 1 nW), APDs with a gain of up to 300 are used to optimize the signal to noise ratio. Maximizing the APDs’ gain while minimizing the excess noise factor (ENF) is essential since the total noise of the diagnostic sets a floor for the minimum level of detectable broadband fluctuations. The APDs’ gain should be high enough that photon noise dominates electronic noise, but not excessive so that the ENF overwhelms plasma fluctuations. A new generation of cooled APDs and optimized preamplifiers exhibits significantly enhanced signal-to-noise compared to a previous generation. Experiments at DIII-D have allowed for characterization and optimization of the ENF vs. gain. Here, a gain of ~100 at 1700 V is found to be near optimal for most plasma conditions. Ion temperature and toroidal velocity fluctuations due to the Edge Harmonic Oscillation (EHO) in Quiescent H-mode (QH) plasmas are presented to demonstrate UF-CHERS’ capabilities.« less

Compact multiwire proportional counters for the detection of fission fragments

NASA Astrophysics Data System (ADS)

Jhingan, Akhil; Sugathan, P.; Golda, K. S.; Singh, R. P.; Varughese, T.; Singh, Hardev; Behera, B. R.; Mandal, S. K.

2009-12-01

Two large area multistep position sensitive (two dimensional) multiwire proportional counters have been developed for experiments involving study of fission dynamics using general purpose scattering chamber facility at IUAC. Both detectors have an active area of 20×10 cm2 and provide position signals in horizontal (X) and vertical (Y) planes, timing signal for time of flight measurements and energy signal giving the differential energy loss in the active volume. The design features are optimized for the detection of low energy heavy ions at very low gas pressures. Special care was taken in setting up the readout electronics, constant fraction discriminators for position signals in particular, to get optimum position and timing resolutions along with high count rate handling capability of low energy heavy ions. A custom made charge sensitive preamplifier, having lower gain and shorter decay time, has been developed for extracting the differential energy loss signal. The position and time resolutions of the detectors were determined to be 1.1 mm full width at half maximum (FWHM) and 1.7 ns FWHM, respectively. The detector could handle heavy ion count rates exceeding 20 kHz without any breakdown. Time of flight signal in combination with differential energy loss signal gives a clean separation of fission fragments from projectile and target like particles. The timing and position signals of the detectors are used for fission coincidence measurements and subsequent extraction of their mass, angular, and total kinetic energy distributions. This article describes systematic study of these fission counters in terms of efficiency, time resolution, count rate handling capability, position resolution, and the readout electronics. The detector has been operated with both five electrode geometry and four electrode geometry, and a comparison has been made in their performances.

Efficient Destruction of Pollutants in Water by a Dual-Reaction-Center Fenton-like Process over Carbon Nitride Compounds-Complexed Cu(II)-CuAlO2.

PubMed

Lyu, Lai; Yan, Dengbiao; Yu, Guangfei; Cao, Wenrui; Hu, Chun

2018-04-03

Carbon nitride compounds (CN) complexed with the in-situ-produced Cu(II) on the surface of CuAlO 2 substrate (CN-Cu(II)-CuAlO 2 ) is prepared via a surface growth process for the first time and exhibits exceptionally high activity and efficiency for the degradation of the refractory pollutants in water through a Fenton-like process in a wide pH range. The reaction rate for bisphenol A removal is ∼25 times higher than that of the CuAlO 2 . According to the characterization, Cu(II) generation on the surface of CuAlO 2 during the surface growth process results in the marked decrease of the surface oxygen vacancies and the formation of the C-O-Cu bridges between CN and Cu(II)-CuAlO 2 in the catalyst. The electron paramagnetic resonance (EPR) analysis and density functional theory (DFT) calculations demonstrate that the dual reaction centers are produced around the Cu and C sites due to the cation-π interactions through the C-O-Cu bridges in CN-Cu(II)-CuAlO 2 . During the Fenton-like reactions, the electron-rich center around Cu is responsible for the efficient reduction of H 2 O 2 to • OH, and the electron-poor center around C captures electrons from H 2 O 2 or pollutants and diverts them to the electron-rich area via the C-O-Cu bridge. Thus, the catalyst exhibits excellent catalytic performance for the refractory pollutant degradation. This study can deepen our understanding on the enhanced Fenton reactivity for water purification through functionalizing with organic solid-phase ligands on the catalyst surface.

Single turnover studies of oxidative halophenol dehalogenation by horseradish peroxidase reveal a mechanism involving two consecutive one electron steps: toward a functional halophenol bioremediation catalyst.

PubMed

Sumithran, Suganya; Sono, Masanori; Raner, Gregory M; Dawson, John H

2012-12-01

Horseradish peroxidase (HRP) catalyzes the oxidative para-dechlorination of the environmental pollutant/carcinogen 2,4,6-trichlorophenol (2,4,6-TCP). A possible mechanism for this reaction is a direct oxygen atom transfer from HRP compound I (HRP I) to trichlorophenol to generate 2,6-dichloro 1,4-benzoquinone, a two-electron transfer process. An alternative mechanism involves two consecutive one-electron transfer steps in which HRP I is reduced to compound II (HRP II) and then to the ferric enzyme as first proposed by Wiese et al. [F.W. Wiese, H.C. Chang, R.V. Lloyd, J.P. Freeman, V.M. Samokyszyn, Arch. Environ. Contam. Toxicol. 34 (1998) 217-222]. To probe the mechanism of oxidative halophenol dehalogenation, the reactions between 2,4,6-TCP and HRP compounds I or II have been investigated under single turnover conditions (i.e., without excess H(2)O(2)) using rapid scan stopped-flow spectroscopy. Addition of 2,4,6-TCP to HRP I leads rapidly to HRP II and then more slowly to the ferric resting state, consistent with a mechanism involving two consecutive one-electron oxidations of the substrate via a phenoxy radical intermediate. HRP II can also directly dechlorinate 2,4,6-TCP as judged by rapid scan stopped-flow and mass spectrometry. This observation is particularly significant since HRP II can only carry out one-electron oxidations. A more detailed understanding of the mechanism of oxidative halophenol dehalogenation will facilitate the use of HRP as a halophenol bioremediation catalyst. Copyright © 2012 Elsevier Inc. All rights reserved.

Homoleptic nickel(II) complexes of redox-tunable pincer-type ligands.

PubMed

Hewage, Jeewantha S; Wanniarachchi, Sarath; Morin, Tyler J; Liddle, Brendan J; Banaszynski, Megan; Lindeman, Sergey V; Bennett, Brian; Gardinier, James R

2014-10-06

Different synthetic methods have been developed to prepare eight new redox-active pincer-type ligands, H(X,Y), that have pyrazol-1-yl flanking donors attached to an ortho-position of each ring of a diarylamine anchor and that have different groups, X and Y, at the para-aryl positions. Together with four previously known H(X,Y) ligands, a series of 12 Ni(X,Y)2 complexes were prepared in high yields by a simple one-pot reaction. Six of the 12 derivatives were characterized by single-crystal X-ray diffraction, which showed tetragonally distorted hexacoordinate nickel(II) centers. The nickel(II) complexes exhibit two quasi-reversible one-electron oxidation waves in their cyclic voltammograms, with half-wave potentials that varied over a remarkable 700 mV range with the average of the Hammett σ(p) parameters of the para-aryl X, Y groups. The one- and two-electron oxidized derivatives [Ni(Me,Me)2](BF4)n (n = 1, 2) were prepared synthetically, were characterized by X-band EPR, electronic spectroscopy, and single-crystal X-ray diffraction (for n = 2), and were studied computationally by DFT methods. The dioxidized complex, [Ni(Me,Me)2](BF4)2, is an S = 2 species, with nickel(II) bound to two ligand radicals. The mono-oxidized complex [Ni(Me,Me)2](BF4), prepared by comproportionation, is best described as nickel(II) with one ligand centered radical. Neither the mono- nor the dioxidized derivative shows any substantial electronic coupling between the metal and their bound ligand radicals because of the orthogonal nature of their magnetic orbitals. On the other hand, weak electronic communication occurs between ligands in the mono-oxidized complex as evident from the intervalence charge transfer (IVCT) transition found in the near-IR absorption spectrum. Band shape analysis of the IVCT transition allowed comparisons of the strength of the electronic interaction with that in the related, previously known, Robin-Day class II mixed valence complex, [Ga(Me,Me)2](2+).

Experimental Measurements of the Secondary Electron Yield in the Experimental Measurement of the Secondary Electron Yield in the PEP-II Particle Accelerator Beam Line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pivi, M.T.F.; Collet, G.; King, F.

Beam instability caused by the electron cloud has been observed in positron and proton storage rings and it is expected to be a limiting factor in the performance of the positron Damping Ring (DR) of future Linear Colliders (LC) such as ILC and CLIC. To test a series of promising possible electron cloud mitigation techniques as surface coatings and grooves, in the Positron Low Energy Ring (LER) of the PEP-II accelerator, we have installed several test vacuum chambers including (i) a special chamber to monitor the variation of the secondary electron yield of technical surface materials and coatings under themore » effect of ion, electron and photon conditioning in situ in the beam line; (ii) chambers with grooves in a straight magnetic-free section; and (iii) coated chambers in a dedicated newly installed 4-magnet chicane to study mitigations in a magnetic field region. In this paper, we describe the ongoing R&D effort to mitigate the electron cloud effect for the LC damping ring, focusing on the first experimental area and on results of the reduction of the secondary electron yield due to in situ conditioning.« less

Hydrogen peroxide and dioxygen activation by dinuclear copper complexes in aqueous solution: hydroxyl radical production initiated by internal electron transfer.

PubMed

Zhu, Qing; Lian, Yuxiang; Thyagarajan, Sunita; Rokita, Steven E; Karlin, Kenneth D; Blough, Neil V

2008-05-21

Dinuclear Cu(II) complexes, CuII2Nn (n = 4 or 5), were recently found to specifically cleave DNA in the presence of a reducing thiol and O2 or in the presence of H2O2 alone. However, CuII2N3 and a closely related mononuclear Cu(II) complex exhibited no selective reaction under either condition. Spectroscopic studies indicate an intermediate is generated from CuII2Nn (n = 4 or 5) and mononuclear Cu(II) solutions in the presence of H2O2 or from CuI2Nn (n = 4 or 5) in the presence of O2. This intermediate decays to generate OH radicals and ligand degradation products at room temperature. The lack of reactivity of the intermediate with a series of added electron donors suggests the intermediate discharges through a rate-limiting intramolecular electron transfer from the ligand to the metal peroxo center to produce an OH radical and a ligand-based radical. These results imply that DNA cleavage does not result from direct reaction with a metal-peroxo intermediate but instead arises from reaction with either OH radicals or ligand-based radicals.

High Electrochemical Sensitivity of TiO2- x Nanosheets and an Electron-Induced Mutual Interference Effect toward Heavy Metal Ions Demonstrated Using X-ray Absorption Fine Structure Spectra.

PubMed

Zhou, Wen-Yi; Li, Shan-Shan; Song, Jie-Yao; Jiang, Min; Jiang, Tian-Jia; Liu, Jin-Yun; Liu, Jin-Huai; Huang, Xing-Jiu

2018-04-03

Mutual interference is a severe issue that occurs during the electrochemical detection of heavy metal ions. This limitation presents a notable drawback for its high sensitivity to specific targets. Here, we present a high electrochemical sensitivity of ∼237.1 μA cm -2 μM -1 toward copper(II) [Cu(II)] based on oxygen-deficient titanium dioxide (TiO 2- x ) nanosheets. We fully demonstrated an atomic-level relationship between electrochemical behaviors and the key factors, including the high-energy (001) facet percentage, oxygen vacancy concentration, surface -OH content, and charge carrier density, is fully demonstrated. These four factors were quantified using Raman, electron spin resonance, X-ray photoelectron spectroscopy spectra, and Mott-Schottky plots. In the mutual interference investigation, we selected cadmium(II) [Cd(II)] as the target ion because of the significant difference in its stripping potential (∼700 mV). The results show that the Cd(II) can enhance the sensitivity of TiO 2- x nanosheets toward Cu(II), exhibiting an electron-induced mutual interference effect, as demonstrated by X-ray absorption fine structure spectra.

Intramolecular electron transfer in cyanide bridged adducts comprising Ru(II)/Ru(III) tetracarboxylate and [Mn(I)(CO)(CN)((t)BuNC)(4)] units.

PubMed

Imhof, Wolfgang; Sterzik, Anke; Krieck, Sven; Schwierz, Markus; Hoffeld, Thomas; Spielberg, Eike T; Plass, Winfried; Patmore, Nathan

2010-07-21

Reaction of mixed valence ruthenium tetracarboxylates [Ru(2)(II,III)(R(1)COO)(2)(R(2)COO)(2)Cl] (R(1) = Me, R(2) = 2,4,6-(i)Pr-Ph or R(1) = R(2) = (t)Bu) with two equivalents of the octahedral manganese complex [Mn(I)(CO)(CN)((t)BuNC)(4)] leads to the formation of cyanide bridged heteronuclear coordination compounds of the general formula {[Ru(2)(II,III)(R(1)COO)(2)(R(2)COO)(2)][Mn(I)(CO)(CN)((t)BuNC)(4)](2)}Cl. In solution an intramolecular electron transfer from manganese towards the multiply bonded Ru(2) core occurs that is verified by EPR and IR spectroscopy, magnetic measurements and DFT calculations. Nevertheless, disproportionation of an initially formed {Mn(I)-Ru(2)(II,III)-Mn(I)}(+) adduct into {Mn(II)-Ru(2)(II,III)-Mn(I)}(2+) and {Mn(I)-Ru(2)(II,II)-Mn(I)} species cannot be completely ruled out.

Electronic Still Camera view of Aft end of Wide Field/Planetary Camera in HST

NASA Image and Video Library

1993-12-06

S61-E-015 (6 Dec 1993) --- A close-up view of the aft part of the new Wide Field/Planetary Camera (WFPC-II) installed on the Hubble Space Telescope (HST). WFPC-II was photographed with the Electronic Still Camera (ESC) from inside Endeavour's cabin as astronauts F. Story Musgrave and Jeffrey A. Hoffman moved it from its stowage position onto the giant telescope. Electronic still photography is a relatively new technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality. The electronic still camera has flown as an experiment on several other shuttle missions.

Synthesis and CV Studies of Dithiol-terminated Metal Terpyridine Complexes

NASA Technical Reports Server (NTRS)

Asano, Sylvia; Fan, Wendy; Ng, Hou-Tee; Han, Jie; Meyyappan, M.

2003-01-01

Transition metal coordination complexes possess unique electronic structures that should be a good model for studying electronic transport behavior at a molecular level. The discrete, multiple redox states, low redox potential and the superb ability to establish contact with other molecular and electronic components by coordination chemistry have made this a subject of investigation for their possible application as active electronic components in molecular devices. We present the synthesis and electrochemical characterization of 4'-thioacetylphenyl-2'2:6',2"-terpyridine iron(II) complex and compare it with a model bis-terpyridine iron(II) complex by cyclic voltammetry. With the use of different working electrodes, the behavior of these complexes show different electron transfer rates.

Manganese Binding Properties of Human Calprotectin Under Conditions of High and Low Calcium: X-ray Crystallographic and Advanced EPR Spectroscopic Analysis

PubMed Central

Gagnon, Derek M.; Brophy, Megan Brunjes; Bowman, Sarah E. J.; Stich, Troy A.; Drennan, Catherine L.; Britt, R. David; Nolan, Elizabeth M.

2015-01-01

The antimicrobial protein calprotectin (CP), a hetero-oligomer of the S100 family members S100A8 and S100A9, is the only identified mammalian Mn(II)-sequestering protein. Human CP uses Ca(II) ions to tune its Mn(II) affinity at a biologically unprecedented hexahistidine site that forms at the S100A8/S100A9 interface, and the molecular basis for this phenomenon requires elucidation. Herein, we investigate the remarkable Mn(II) coordination chemistry of human CP using X-ray crystallography as well as continuous wave (CW) and pulse electron paramagnetic resonance (EPR) spectroscopies. An X-ray crystallographic structure of Mn(II)-CP containing one Mn(II), two Ca(II), and two Na(I) ions per CP heterodimer is reported. The CW EPR spectrum of Ca(II)- and Mn(II)-bound CP prepared with a 10:0.9:1 Ca(II):Mn(II):CP ratio is characterized by an unusually low zero-field splitting of 485 MHz (E/D = 0.30) for the S = 5/2 Mn(II) ion, consistent with the high symmetry of the His6 binding site observed crystallographically. Results from electron spin-echo envelope modulation and electron nuclear double resonance experiments reveal that the six Mn(II)-coordinating histidine residues of Ca(II)- and Mn(II)-bound CP are spectroscopically equivalent. The observed 15N (I = 1/2) hyperfine couplings (A) arise from two distinct classes of nitrogen atoms: the coordinating ε-nitrogen of the imidazole ring of each histidine ligand (A = [3.45, 3.71, 5.91] MHz) and the distal δ-nitrogen (A = [0.11, 0.18, 0.42] MHz). In the absence of Ca(II), the binding affinity of CP for Mn(II) drops by ca. two orders of magnitude and coincides with Mn(II) binding at the His6 site as well as other sites. This study demonstrates the role of Ca(II) in enabling high-affinity and specific binding of Mn(II) to the His6 site of human calprotectin. PMID:25597447

Manganese Binding Properties of Human Calprotectin under Conditions of High and Low Calcium: X-ray Crystallographic and Advanced Electron Paramagnetic Resonance Spectroscopic Analysis

DOE PAGES

Gagnon, Derek M.; Brophy, Megan Brunjes; Bowman, Sarah E. J.; ...

2015-01-18

The antimicrobial protein calprotectin (CP), a hetero-oligomer of the S100 family members S100A8 and S100A9, is the only identified mammalian Mn(II)-sequestering protein. Human CP uses Ca(II) ions to tune its Mn(II) affinity at a biologically unprecedented hexahistidine site that forms at the S100A8/S100A9 interface, and the molecular basis for this phenomenon requires elucidation. Here in this paper, we investigate the remarkable Mn(II) coordination chemistry of human CP using X-ray crystallography as well as continuous-wave (CW) and pulse electron paramagnetic resonance (EPR) spectroscopies. An X-ray crystallographic structure of Mn(II)-CP containing one Mn(II), two Ca(II), and two Na(I) ions per CP heterodimermore » is reported. The CW EPR spectrum of Ca(II)- and Mn(II)-bound CP prepared with a 10:0.9:1 Ca(II):Mn(II):CP ratio is characterized by an unusually low zero-field splitting of 485 MHz (E/D = 0.30) for the S = 5/2 Mn(II) ion, consistent with the high symmetry of the His6 binding site observed crystallographically. Results from electron spin–echo envelope modulation and electron–nuclear double resonance experiments reveal that the six Mn(II)-coordinating histidine residues of Ca(II)- and Mn(II)-bound CP are spectroscopically equivalent. The observed 15N (I = 1/2) hyperfine couplings (A) arise from two distinct classes of nitrogen atoms: the coordinating ε-nitrogen of the imidazole ring of each histidine ligand (A = [3.45, 3.71, 5.91] MHz) and the distal δ-nitrogen (A = [0.11, 0.18, 0.42] MHz). In the absence of Ca(II), the binding affinity of CP for Mn(II) drops by two to three orders of magnitude and coincides with Mn(II) binding at the His6 site as well as other sites. This study demonstrates the role of Ca(II) in enabling high-affinity and specific binding of Mn(II) to the His 6 site of human calprotectin.« less

Manganese Binding Properties of Human Calprotectin under Conditions of High and Low Calcium: X-ray Crystallographic and Advanced Electron Paramagnetic Resonance Spectroscopic Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gagnon, Derek M.; Brophy, Megan Brunjes; Bowman, Sarah E. J.

The antimicrobial protein calprotectin (CP), a hetero-oligomer of the S100 family members S100A8 and S100A9, is the only identified mammalian Mn(II)-sequestering protein. Human CP uses Ca(II) ions to tune its Mn(II) affinity at a biologically unprecedented hexahistidine site that forms at the S100A8/S100A9 interface, and the molecular basis for this phenomenon requires elucidation. Here in this paper, we investigate the remarkable Mn(II) coordination chemistry of human CP using X-ray crystallography as well as continuous-wave (CW) and pulse electron paramagnetic resonance (EPR) spectroscopies. An X-ray crystallographic structure of Mn(II)-CP containing one Mn(II), two Ca(II), and two Na(I) ions per CP heterodimermore » is reported. The CW EPR spectrum of Ca(II)- and Mn(II)-bound CP prepared with a 10:0.9:1 Ca(II):Mn(II):CP ratio is characterized by an unusually low zero-field splitting of 485 MHz (E/D = 0.30) for the S = 5/2 Mn(II) ion, consistent with the high symmetry of the His6 binding site observed crystallographically. Results from electron spin–echo envelope modulation and electron–nuclear double resonance experiments reveal that the six Mn(II)-coordinating histidine residues of Ca(II)- and Mn(II)-bound CP are spectroscopically equivalent. The observed 15N (I = 1/2) hyperfine couplings (A) arise from two distinct classes of nitrogen atoms: the coordinating ε-nitrogen of the imidazole ring of each histidine ligand (A = [3.45, 3.71, 5.91] MHz) and the distal δ-nitrogen (A = [0.11, 0.18, 0.42] MHz). In the absence of Ca(II), the binding affinity of CP for Mn(II) drops by two to three orders of magnitude and coincides with Mn(II) binding at the His6 site as well as other sites. This study demonstrates the role of Ca(II) in enabling high-affinity and specific binding of Mn(II) to the His 6 site of human calprotectin.« less

Temperature Independent Catalytic Two-Electron Reduction of Dioxygen by Ferrocenes with a Tris[2-(2-pyridyl)ethyl]amine-Copper(II) Catalyst in the Presence of Perchloric Acid

PubMed Central

Das, Dipanwita; Lee, Yong-Min; Ohkubo, Kei; Nam, Wonwoo; Karlin, Kenneth D.; Fukuzumi, Shunichi

2013-01-01

Selective two-electron plus two-proton (2e−/2H+) reduction of O2 to hydrogen peroxide by ferrocene (Fc) or 1,1′-dimethylferrocene (Me2Fc) in the presence of perchloric acid is catalyzed efficiently by a mononuclear copper(II) complex, [CuII(tepa)]2+ {tepa = tris[2-(2-pyridyl)ethyl]amine} (1) in acetone. The E1/2 value for [CuII(tepa)]2+ as measured by cyclic voltammetry is 0.07 V vs Fc/Fc+ in acetone, being significantly positive, which makes it possible to use relatively weak one-electron reductants such as Fc and Me2Fc for the overall two-electron reduction of O2. Fast electron transfer from Fc or Me2Fc to 1 affords the corresponding CuI complex, [CuI(tepa)]+ (2), which reacts at low temperature (193 K) with O2, however only in presence of HClO4 to afford the hydroperoxo complex, [CuII(tepa)(OOH)]2+ (3). The detailed kinetic study on the homogeneous catalytic system reveals the rate-determining step to be the O2-binding process in the presence of HClO4 at lower temperature as well as at room temperature. The O2-binding kinetics in the presence of HClO4 were studied, demonstrating that the rate of formation of the hydroperoxo complex (3) as well as the overall catalytic reaction remained virtually the same with changing temperature. The apparent lack of an activation energy for the catalytic two-electron reduction of O2 is shown to result from the existence of a pre-equilibrium between 2 and O2 prior to the formation of the hydroperoxo complex 3. No further reduction of [CuII(tepa)(OOH)]2+ (3) by Fc or Me2Fc occurred, and instead 3 is protonated by HClO4 to yield H2O2 accompanied by regeneration of 1, thus completing the catalytic cycle for the two-electron reduction of O2 by Fc or Me2Fc. PMID:23394287

Absorption enhancement in type-II coupled quantum rings due to existence of quasi-bound states

NASA Astrophysics Data System (ADS)

Hsieh, Chi-Ti; Lin, Shih-Yen; Chang, Shu-Wei

2018-02-01

The absorption of type-II nanostructures is often weaker than type-I counterpart due to spatially separated electrons and holes. We model the bound-to-continuum absorption of type-II quantum rings (QRs) using a multiband source-radiation approach using the retarded Green function in the cylindrical coordinate system. The selection rules due to the circular symmetry for allowed transitions of absorption are utilized. The bound-tocontinuum absorptions of type-II GaSb coupled and uncoupled QRs embedded in GaAs matrix are compared here. The GaSb QRs act as energy barriers for electrons but potential wells for holes. For the coupled QR structure, the region sandwiched between two QRs forms a potential reservoir of quasi-bound electrons. Electrons in these states, though look like bound ones, would ultimately tunnel out of the reservoir through barriers. Multiband perfectly-matched layers are introduced to model the tunneling of quasi-bound states into open space. Resonance peaks are observed on the absorption spectra of type-II coupled QRs due to the formation of quasi-bound states in conduction bands, but no resonance exist in the uncoupled QR. The tunneling time of these metastable states can be extracted from the resonance and is in the order of ten femtoseconds. Absorption of coupled QRs is significantly enhanced as compared to that of uncoupled ones in certain spectral windows of interest. These features may improve the performance of photon detectors and photovoltaic devices based on type-II semiconductor nanostructures.

Surface Charge Transfer Doping via Transition Metal Oxides for Efficient p-Type Doping of II-VI Nanostructures.

PubMed

Xia, Feifei; Shao, Zhibin; He, Yuanyuan; Wang, Rongbin; Wu, Xiaofeng; Jiang, Tianhao; Duhm, Steffen; Zhao, Jianwei; Lee, Shuit-Tong; Jie, Jiansheng

2016-11-22

Wide band gap II-VI nanostructures are important building blocks for new-generation electronic and optoelectronic devices. However, the difficulty of realizing p-type conductivity in these materials via conventional doping methods has severely handicapped the fabrication of p-n homojunctions and complementary circuits, which are the fundamental components for high-performance devices. Herein, by using first-principles density functional theory calculations, we demonstrated a simple yet efficient way to achieve controlled p-type doping on II-VI nanostructures via surface charge transfer doping (SCTD) using high work function transition metal oxides such as MoO 3 , WO 3 , CrO 3 , and V 2 O 5 as dopants. Our calculations revealed that these oxides were capable of drawing electrons from II-VI nanostructures, leading to accumulation of positive charges (holes injection) in the II-VI nanostructures. As a result, Fermi levels of the II-VI nanostructures were shifted toward the valence band regions after surface modifications, along with the large enhancement of work functions. In situ ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy characterizations verified the significant interfacial charge transfer between II-VI nanostructures and surface dopants. Both theoretical calculations and electrical transfer measurements on the II-VI nanostructure-based field-effect transistors clearly showed the p-type conductivity of the nanostructures after surface modifications. Strikingly, II-VI nanowires could undergo semiconductor-to-metal transition by further increasing the SCTD level. SCTD offers the possibility to create a variety of electronic and optoelectronic devices from the II-VI nanostructures via realization of complementary doping.

HERSCHEL GALACTIC PLANE SURVEY OF [N ii] FINE STRUCTURE EMISSION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldsmith, Paul F.; Yıldız, Umut A.; Langer, William D.

2015-12-01

We present the first large-scale high angular resolution survey of ionized nitrogen in the Galactic Plane through emission of its two fine structure transitions ([N ii]) at 122 and 205 μm. The observations were largely obtained with the PACS instrument onboard the Herschel Space Observatory. The lines of sight were in the Galactic plane, following those of the Herschel OTKP project GOT C+. Both lines are reliably detected at the 10{sup −8}–10{sup −7} Wm{sup −2} sr{sup −1} level over the range –60° ≤ l ≤ 60°. The rms of the intensity among the 25 PACS spaxels of a given pointingmore » is typically less than one third of the mean intensity, showing that the emission is extended. [N ii] is produced in gas in which hydrogen is ionized, and collisional excitation is by electrons. The ratio of the two fine structure transitions provides a direct measurement of the electron density, yielding n(e) largely in the range 10–50 cm{sup −3} with an average value of 29 cm{sup −3} and N{sup +} column densities 10{sup 16}–10{sup 17} cm{sup −2}. [N ii] emission is highly correlated with that of [C ii], and we calculate that between 1/3 and 1/2 of the [C ii] emission is associated with the ionized gas. The relatively high electron densities indicate that the source of the [N ii] emission is not the warm ionized medium (WIM), which has electron densities more than 100 times smaller. Possible origins of the observed [N ii] include the ionized surfaces of dense atomic and molecular clouds, the extended low-density envelopes of H ii regions, and low-filling factor high-density fluctuations of the WIM.« less

The second Cu(II)-binding site in a proton-rich environment interferes with the aggregation of amyloid-beta(1-40) into amyloid fibrils.

PubMed

Jun, Sangmi; Gillespie, Joel R; Shin, Byong-kyu; Saxena, Sunil

2009-11-17

The overall morphology and Cu(II) ion coordination for the aggregated amyloid-beta(1-40) [Abeta(1-40)] in N-ethylmorpholine (NEM) buffer are affected by Cu(II) ion concentration. This effect is investigated by transmission electron microscopy (TEM), atomic force microscopy (AFM), and electron spin echo envelope modulation (ESEEM) spectroscopy. At lower than equimolar concentrations of Cu(II) ions, fibrillar aggregates of Abeta(1-40) are observed. At these concentrations of Cu(II), the monomeric and fibrillar Abeta(1-40) ESEEM data indicate that the Cu(II) ion is coordinated by histidine residues. For aggregated Abeta(1-40) at a Cu(II):Abeta molar ratio of 2:1, TEM and AFM images show both linear fibrils and granular amorphous aggregates. The ESEEM spectra show that the multi-histidine coordination for Cu(II) ion partially breaks up and becomes exposed to water or exchangeable protons of the peptide at a higher Cu(II) concentration. Since the continuous-wave electron spin resonance results also suggest two copper-binding sites in Abeta(1-40), the proton ESEEM peak may arise from the second copper-binding site, which may be significantly involved in the formation of granular amorphous aggregates. Thioflavin T fluorescence and circular dichroism experiments also show that Cu(II) inhibits the formation of fibrils and induces a nonfibrillar beta-sheet conformation. Therefore, we propose that Abeta(1-40) has a second copper-binding site in a proton-rich environment and the second binding Cu(II) ion interferes with a conformational transition into amyloid fibrils, inducing the formation of granular amorphous aggregates.

Development of improved pyroelectric detectors. Measurements of pyroelectric material characteristics and FET characteristics

NASA Technical Reports Server (NTRS)

Weiner, S.; Beerman, H. P.; Schwarz, F. C.

1990-01-01

Research was undertaken to improve the detectivity of the pyroelectric detector with the ultimate goal of operation at or near the temperature-noise limit. Two general areas of investigation were undertaken: (1) to improve responsivity through the use of new materials; and (2) to reduce noise through improved field effect transistor characteristics, and improved electroding of the pyroelectric material. FET's are being obtained from various manufacturers, evaulated, and selected units tested for evaluation of characteristics critical to their use as preamplifiers with pyroelectric detectors.

Influence of satellite vibration on radio over IsOWC system

NASA Astrophysics Data System (ADS)

Zong, Kang; Zhu, Jiang

2017-07-01

In this paper, we analyze the influence of satellite vibration on radio over intersatellite optical wireless communication (IsOWC) system with an optical booster amplifier (OBA) and an optical preamplifier. The closed-form expressions of radio frequency (RF) gain, noise figure (NF) and spurious-free dynamic range (SFDR) are derived in the presence of pointing jitter taking consideration of bias error. Numerical results for RF gain, NF and SFDR are given for demonstration. Results indicate that the bias error obviously deteriorates the performance of the radio over IsOWC system.

Cryogenic readout for multiple VUV4 Multi-Pixel Photon Counters in liquid xenon

NASA Astrophysics Data System (ADS)

Di Giovanni, A.

2018-03-01

This work concerned the preliminary tests and characterization of a cryogenic preamplifier board for an array made of 16 S13370-3050CN (VUV4 family) Multi-Pixel Photon Counters manufactured by Hamamatsu and operated at liquid xenon temperature. The proposed prototype is based on the use of the Analog Devices AD8011 current feedback operational amplifier. The detector allows for single photon detection, making this device a promising choice for the future generation of neutrino and dark matter detectors based on liquid xenon targets.

Observation of beta and X rays with 3-D-architecture silicon microstrip sensors

NASA Astrophysics Data System (ADS)

Kenney, C. J.; Parker, S. I.; Krieger, B.; Ludewigt, B.; Dubbs, T. P.; Sadrozinski, H.

2001-04-01

The first silicon radiation sensors based on the three-dimensional (3-D) architecture have been successfully fabricated. X-ray spectra from iron-55 and americium-241 have been recorded by reading out a 3-D architecture detector via wire bonds to a low-noise, charge-sensitive preamplifier. Using a beta source, coincidences between a 3-D sensor and a plastic scintillator were observed. This is the first observation of ionizing radiation using a silicon sensor based on the 3-D architecture. Details of the apparatus and measurements are described.

Current status of Kumgang laser system

NASA Astrophysics Data System (ADS)

Kong, Hong Jin; Park, Sangwoo; Ahn, HeeKyung; Lee, Hwihyeong; Oh, Jungsuk; Kim, Jom Sool

2015-02-01

In KAIST, Kumgang laser is being developed for demonstration of the kW level coherent beam combination using stimulated Brillouin scattering phase conjugation mirrors. It will combine 4 modules of DPSSL rod amplifier which produces 1 kW output power. It is composed of the single frequency front-end, pre-amplifier module, and main amplifier. The output powers of the pre-amp and main amplifier module are 200 W (20 mJ @ 10 kHz / 10 ns) and 1.07kW (107 mJ @ 10 kHz / 10 ns), respectively.

Sounding of the Ion Energization Region: Resolving Ambiguities

NASA Technical Reports Server (NTRS)

LaBelle, James

2003-01-01

Dartmouth College provided a single-channel high-frequency wave receiver to the Sounding of the Ion Energization Region: Resolving Ambiguities (SIERRA) rocket experiment launched from Poker Flat, Alaska, in January 2002. The receiver used signals from booms, probes, preamplifiers, and differential amplifiers provided by Cornell University coinvestigators. Output was to a dedicated 5 MHz telemetry link provided by WFF, with a small amount of additional Pulse Code Modulation (PCM) telemetry required for the receiver gain information. We also performed preliminary analysis of the data. The work completed is outlined below, in chronological order.

Standardized Testing Capabilities at U.S. Navy Transducer Repair Facilities

DTIC Science & Technology

1972-08-01

The following acoustical and electrical tests can be performed at the TRFs by the use of an AN/FQM-lO(V) Sonar Test Set, a. Low level impedance...It fits into the sub- system as shown in Fig 2-2. A switch located at the preamplifier is used to select either high or low power operation. The...may also be selected. 2.6.2 Signal Amplification. A low noise differential premnplifier with selectable gains from -20 dB to +60 dB in 10 dB steps is

Design and implementation of the NaI(Tl)/CsI(Na) detectors output signal generator

NASA Astrophysics Data System (ADS)

Zhou, Xu; Liu, Cong-Zhan; Zhao, Jian-Ling; Zhang, Fei; Zhang, Yi-Fei; Li, Zheng-Wei; Zhang, Shuo; Li, Xu-Fang; Lu, Xue-Feng; Xu, Zhen-Ling; Lu, Fang-Jun

2014-02-01

We designed and implemented a signal generator that can simulate the output of the NaI(Tl)/CsI(Na) detectors' pre-amplifier onboard the Hard X-ray Modulation Telescope (HXMT). Using the development of the FPGA (Field Programmable Gate Array) with VHDL language and adding a random constituent, we have finally produced the double exponential random pulse signal generator. The statistical distribution of the signal amplitude is programmable. The occurrence time intervals of the adjacent signals contain negative exponential distribution statistically.

Carrier-envelope phase stabilization and control of 1 kHz, 6 mJ, 30 fs laser pulses from a Ti:sapphire regenerative amplifier.

PubMed

Chen, Shouyuan; Chini, Michael; Wang, He; Yun, Chenxia; Mashiko, Hiroki; Wu, Yi; Chang, Zenghu

2009-10-20

Carrier-envelope (CE) phase stabilization of a two-stage chirped pulse amplifier laser system with regenerative amplification as the preamplifier is demonstrated. The CE phase stability of this laser system is found to have a 90 mrad rms error averaged over 50 laser shots for a locking period of 4.5 h. The CE phase locking was confirmed unambiguously by experimental observation of the 2pi periodicity of the high-order harmonic spectrum generated by double optical gating.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Jinyuan

A digitization scheme of sub-microampere current using a commercial comparator with adjustable hysteresis and FPGA-based Wave Union TDC has been tested. The comparator plus a few passive components forms a current controlled oscillator and the input current is sent into the hysteresis control pin. The input current is converted into the transition times of the oscillations, which are digitized with a Wave Union TDC in FPGA and the variation of the transition times reflects the variation of the input current. Preliminary tests show that input charges < 25 fC can be measured at > 50 M samples/s without a preamplifier.

Operational testing of system for automatic sleep analysis

NASA Technical Reports Server (NTRS)

Kellaway, P.

1972-01-01

Tables on the performance, under operational conditions, of an automatic sleep monitoring system are presented. Data are recorded from patients who were undergoing heart and great vessel surgery. This study resulted in cap, electrode, and preamplifier improvements. Children were used to test the sleep analyzer and medical console write out units. From these data, an automatic voltage control circuit for the analyzer was developed. A special circuitry for obviating the possibility of incorrect sleep staging due to the presence of a movement artifact was also developed as a result of the study.

From chemolithoautotrophs to electrolithoautotrophs: CO2 fixation by Fe(II)-oxidizing bacteria coupled with direct uptake of electrons from solid electron sources.

PubMed

Ishii, Takumi; Kawaichi, Satoshi; Nakagawa, Hirotaka; Hashimoto, Kazuhito; Nakamura, Ryuhei

2015-01-01

At deep-sea vent systems, hydrothermal emissions rich in reductive chemicals replace solar energy as fuels to support microbial carbon assimilation. Until recently, all the microbial components at vent systems have been assumed to be fostered by the primary production of chemolithoautotrophs; however, both the laboratory and on-site studies demonstrated electrical current generation at vent systems and have suggested that a portion of microbial carbon assimilation is stimulated by the direct uptake of electrons from electrically conductive minerals. Here we show that chemolithoautotrophic Fe(II)-oxidizing bacterium, Acidithiobacillus ferrooxidans, switches the electron source for carbon assimilation from diffusible Fe(2+) ions to an electrode under the condition that electrical current is the only source of energy and electrons. Site-specific marking of a cytochrome aa3 complex (aa3 complex) and a cytochrome bc1 complex (bc1 complex) in viable cells demonstrated that the electrons taken directly from an electrode are used for O2 reduction via a down-hill pathway, which generates proton motive force that is used for pushing the electrons to NAD(+) through a bc1 complex. Activation of carbon dioxide fixation by a direct electron uptake was also confirmed by the clear potential dependency of cell growth. These results reveal a previously unknown bioenergetic versatility of Fe(II)-oxidizing bacteria to use solid electron sources and will help with understanding carbon assimilation of microbial components living in electronically conductive chimney habitats.

From chemolithoautotrophs to electrolithoautotrophs: CO2 fixation by Fe(II)-oxidizing bacteria coupled with direct uptake of electrons from solid electron sources

PubMed Central

Ishii, Takumi; Kawaichi, Satoshi; Nakagawa, Hirotaka; Hashimoto, Kazuhito; Nakamura, Ryuhei

2015-01-01

At deep-sea vent systems, hydrothermal emissions rich in reductive chemicals replace solar energy as fuels to support microbial carbon assimilation. Until recently, all the microbial components at vent systems have been assumed to be fostered by the primary production of chemolithoautotrophs; however, both the laboratory and on-site studies demonstrated electrical current generation at vent systems and have suggested that a portion of microbial carbon assimilation is stimulated by the direct uptake of electrons from electrically conductive minerals. Here we show that chemolithoautotrophic Fe(II)-oxidizing bacterium, Acidithiobacillus ferrooxidans, switches the electron source for carbon assimilation from diffusible Fe2+ ions to an electrode under the condition that electrical current is the only source of energy and electrons. Site-specific marking of a cytochrome aa3 complex (aa3 complex) and a cytochrome bc1 complex (bc1 complex) in viable cells demonstrated that the electrons taken directly from an electrode are used for O2 reduction via a down-hill pathway, which generates proton motive force that is used for pushing the electrons to NAD+ through a bc1 complex. Activation of carbon dioxide fixation by a direct electron uptake was also confirmed by the clear potential dependency of cell growth. These results reveal a previously unknown bioenergetic versatility of Fe(II)-oxidizing bacteria to use solid electron sources and will help with understanding carbon assimilation of microbial components living in electronically conductive chimney habitats. PMID:26500609

Commissioning and Early Operation Experience of the NSLS-II Storage Ring RF System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, F.; Rose, J.; Cupolo, J.

2015-05-03

The National Synchrotron Light Source II (NSLS-II) is a 3 GeV electron X-ray user facility commissioned in 2014. The storage ring RF system, essential for replenishing energy loss per turn of the electrons, consists of digital low level RF controllers, 310 kW CW klystron transmitters, CESR-B type superconducting cavities, as well as a supporting cryogenic system. Here we will report on RF commissioning and early operation experience of the system for beam current up to 200mA.

Electron heat transport comparison in the Large Helical Device and TJ-II

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia, J.; Dies, J.; Castejon, F.

2007-10-15

The electron heat transport in the Large Helical Device (LHD) [K. Ida, T. Shimozuma, H. Funaba et al., Phys. Rev. Lett. 91, 085003 (2003)] and TJ-II [F. Castejon, V. Tribaldos, I. Garcia-Cortes, E. de la Luna, J. Herranz, I. Pastor, T. Estrada, and TJ-II Team, Nucl. Fusion 42, 271 (2002)] is analyzed by means of the TOTAL [K. Yamazaki and T. Amano, Nucl. Fusion 32, 4 (1992)] and PRETOR-Stellarator [J. Dies, F. Castejon, J. M. Fontdecaba, J. Fontanet, J. Izquierdo, G. Cortes, and C. Alejaldre, Proceedings of the 29th European Physical Society Conference on Plasma Physics and Controlled Fusion, Montreux,more » 2002, Europhysics Conference Abstracts, 2004, Vol. 26B, P-5.027] plasma simulation codes and assuming a global transport model mixing GyroBohm-like drift wave model and other drift wave model with shorter wavelength. The stabilization of the GyroBohm-like model by the ExB shear has been also taken into account. Results show how such kind of electron heat transport can simulate experimental evidence in both devices, leading to the electron internal transport barrier (eITB) formation in the LHD and to the so-called 'enhanced heat confinement regimes' in TJ-II when electron density is low enough. Therefore, two sources for the anomalous electron heat transport can coexist in plasmas with eITB; however, for each device the relative importance of anomalous and neoclassical transport can be different.« less

Functionalization of a nanostructured hydroxyapatite with Cu(II) compounds as a pesticide: in situ transmission electron microscopy and environmental scanning electron microscopy observations of treated Vitis vinifera L. leaves.

PubMed

Battiston, Enrico; Salvatici, Maria C; Lavacchi, Alessandro; Gatti, Antonietta; Di Marco, Stefano; Mugnai, Laura

2018-02-19

The present study evaluated a biocompatible material for plant protection with the aim of reducing the amount of active substance applied. We used a synthetic hydroxyapatite (HA) that has been studied extensively as a consequence of its bioactivity and biocompatibility. An aggregation between HA nanoparticles and four Cu(II) compounds applied to Vitis vinifera L. leaves as a pesticide was studied. Formulations were characterized by X-ray diffraction (XRD), dynamic light scattering (DLS) and electron microscopy and applied in planta to verify particle aggregation and efficiency in controlling the pathogen Plasmopara viticola. The XRD patterns showed different crystalline phases dependig on the Cu(II) compound formulated with HA particles, DLS showed that nanostructured particles are stable as aggregates out of the nanometer range and, in all formulations, transmission electron microscopy (TEM) and environmental scanning electron microscopy (ESEM) microscopy showed large aggregates which were partially nanostructured and were recognized as stable in their micrometric dimensions. Such particles did not show phytotoxic effects after their application in planta. A formulation based on HA and a soluble Cu(II) compound showed promising results in the control of the fungal pathogen, confirming the potential role of HA as an innovative delivery system of Cu(II) ions. The present work indicates the possibility of improving the biological activity of a bioactive substance by modifying its structure through an achievable formulation with a biocompatible material. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Generic tags for Mn(ii) and Gd(iii) spin labels for distance measurements in proteins.

PubMed

Yang, Yin; Gong, Yan-Jun; Litvinov, Aleksei; Liu, Hong-Kai; Yang, Feng; Su, Xun-Cheng; Goldfarb, Daniella

2017-10-11

High-affinity chelating tags for Gd(iii) and Mn(ii) ions that provide valuable high-resolution distance restraints for biomolecules were used as spin labels for double electron-electron resonance (DEER) measurements. The availability of a generic tag that can bind both metal ions and provide a narrow and predictable distance distribution for both ions is attractive owing to their different EPR-related characteristics. Herein we introduced two paramagnetic tags, 4PSPyMTA and 4PSPyNPDA, which are conjugated to cysteine residues through a stable thioether bond, forming a short and, depending on the metal ion coordination mode, a rigid tether with the protein. These tags exhibit high affinity for both Mn(ii) and Gd(iii) ions. The DEER performance of the 4PSPyMTA and 4PSPyNPDA tags, in complex with Gd(iii) or Mn(ii), was evaluated for three double cysteine mutants of ubiquitin, and the Gd(iii)-Gd(iii) and Mn(ii)-Mn(ii) distance distributions they generated were compared. All three Gd(iii) complexes of the ubiquitin-PyMTA and ubiquitin-PyNPDA conjugates produced similar and expected distance distributions. In contrast, significant variations in the maxima and widths of the distance distributions were observed for the Mn(ii) analogs. Furthermore, whereas PyNPDA-Gd(iii) and PyNPDA-Mn(ii) delivered similar distance distributions, appreciable differences were observed for two mutants with PyMTA, with the Mn(ii) analog exhibiting a broader distance distribution and shorter distances. ELDOR (electron-electron double resonance)-detected NMR measurements revealed some distribution in the Mn(ii) coordination environment for the protein conjugates of both tags but not for the free tags. The broader distance distributions generated by 4PSPyMTA-Mn(ii), as compared with Gd(iii), were attributed to the distributed location of the Mn(ii) ion within the PyMTA chelate owing to its smaller size and lower coordination number that leave the pyridine nitrogen uncoordinated. Accordingly, in terms of distance resolution, 4PSPyNPDA can serve as an effective generic tag for Gd(iii) and Mn(ii), whereas 4PSPyMTA is efficient for Gd(iii) only. This comparison between Gd(iii) and Mn(ii) suggests that PyMTA model compounds may not predict sufficiently well the performance of PyMTA-Mn(ii) as a tag for high-resolution distance measurements in proteins because the protein environment can influence its coordination mode.

Cation Effects on the Electron-Acceptor Side of Photosystem II.

PubMed

Khan, Sahr; Sun, Jennifer S; Brudvig, Gary W

2015-06-18

The normal pathway of electron transfer on the electron-acceptor side of photosystem II (PSII) involves electron transfer from quinone A, QA, to quinone B, QB. It is possible to redirect electrons from QA(-) to water-soluble Co(III) complexes, which opens a new avenue for harvesting electrons from water oxidation by immobilization of PSII on electrode surfaces. Herein, the kinetics of electron transfer from QA(-) to [Co(III)(terpy)2](3+) (terpy = 2,2';6',2″-terpyridine) are investigated with a spectrophotometric assay revealing that the reaction follows Michaelis-Menten saturation kinetics, is inhibited by cations, and is not affected by variation of the QA reduction potential. A negatively charged site on the stromal surface of the PSII protein complex, composed of glutamic acid residues near QA, is hypothesized to bind cations, especially divalent cations. The cations are proposed to tune the redox properties of QA through electrostatic interactions. These observations may thus explain the molecular basis of the effect of divalent cations like Ca(2+), Sr(2+), Mg(2+), and Zn(2+) on the redox properties of the quinones in PSII, which has previously been attributed to long-range conformational changes propagated from divalent cations binding to the Ca(II)-binding site in the oxygen-evolving complex on the lumenal side of the PSII complex.

Domestic Production Issues in Chromium and Platinum-Group Metals

DTIC Science & Technology

1988-09-01

iridium, and minor amounts of osmium. 12 Uses. Platinum-group metals (PGM) are critical as catalysts in fossil fuel processing and electronic...metals (PGM) were then described as critical in fossil fuel production, and in electronic and electrical components. The international market is...this research process . ii Table of Contents Page Preface.. .............. ii List of Figures ................ vi List of Tables ................ vi

Rational Design of an Electron-Reservoir Pt(II) Complex for Efficient Photocatalytic Hydrogen Production from Water.

PubMed

Whang, Dong Ryeol; Park, Soo Young

2015-10-12

Herein we report a Pt(II) complex containing a 4,4'-bis[4-(triphenylsilyl)phenyl]-2,2'-bipyridine ligand as a molecular catalyst for water splitting. Systematic studies of the electrochemical and electronic properties of this catalyst, in comparison with two control complexes, reveal electron-reservoir characteristics upon two-electron reduction. A turnover number of 510,000 was recorded by employing this complex as a water reduction catalyst in combination with a state-of-the-art photosensitizer and N,N-dimethylaniline as a sacrificial electron donor, which represents a large improvement over the control complexes that do not contain the tetraphenylsilyl ligand substitution. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Type IV pili of Acidithiobacillus ferrooxidans can transfer electrons from extracellular electron donors.

PubMed

Li, Yongquan; Li, Hongyu

2014-03-01

Studies on Acidithiobacillus ferrooxidans accepting electrons from Fe(II) have previously focused on cytochrome c. However, we have discovered that, besides cytochrome c, type IV pili (Tfp) can transfer electrons. Here, we report conduction by Tfp of A. ferrooxidans analyzed with a conducting-probe atomic force microscope (AFM). The results indicate that the Tfp of A. ferrooxidans are highly conductive. The genome sequence of A. ferrooxidans ATCC 23270 contains two genes, pilV and pilW, which code for pilin domain proteins with the conserved amino acids characteristic of Tfp. Multiple alignment analysis of the PilV and PilW (pilin) proteins indicated that pilV is the adhesin gene while pilW codes for the major protein element of Tfp. The likely function of Tfp is to complete the circuit between the cell surface and Fe(II) oxides. These results indicate that Tfp of A. ferrooxidans might serve as biological nanowires transferring electrons from the surface of Fe(II) oxides to the cell surface. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

One-electron oxidation of electronically diverse manganese(III) and nickel(II) salen complexes: transition from localized to delocalized mixed-valence ligand radicals.

PubMed

Kurahashi, Takuya; Fujii, Hiroshi

2011-06-01

Ligand radicals from salen complexes are unique mixed-valence compounds in which a phenoxyl radical is electronically linked to a remote phenolate via a neighboring redox-active metal ion, providing an opportunity to study electron transfer from a phenolate to a phenoxyl radical mediated by a redox-active metal ion as a bridge. We herein synthesize one-electron-oxidized products from electronically diverse manganese(III) salen complexes in which the locus of oxidation is shown to be ligand-centered, not metal-centered, affording manganese(III)-phenoxyl radical species. The key point in the present study is an unambiguous assignment of intervalence charge transfer bands by using nonsymmetrical salen complexes, which enables us to obtain otherwise inaccessible insight into the mixed-valence property. A d(4) high-spin manganese(III) ion forms a Robin-Day class II mixed-valence system, in which electron transfer is occurring between the localized phenoxyl radical and the phenolate. This is in clear contrast to a d(8) low-spin nickel(II) ion with the same salen ligand, which induces a delocalized radical (Robin-Day class III) over the two phenolate rings, as previously reported by others. The present findings point to a fascinating possibility that electron transfer could be drastically modulated by exchanging the metal ion that bridges the two redox centers. © 2011 American Chemical Society

Making the invisible visible: improved electrospray ion formation of metalloporphyrins/-phthalocyanines by attachment of the formate anion (HCOO(-)).

PubMed

Hitzenberger, Jakob Felix; Dammann, Claudia; Lang, Nina; Lungerich, Dominik; García-Iglesias, Miguel; Bottari, Giovanni; Torres, Tomás; Jux, Norbert; Drewello, Thomas

2016-02-21

A protocol is developed for the coordination of the formate anion (HCOO(-)) to neutral metalloporphyrins (Pors) and -phthalocyanines (Pcs) containing divalent metals as a means to improve their ion formation in electrospray ionization (ESI). This method is particularly useful when the oxidation of the neutral metallomacrocycle fails. While focusing on Zn(II)Pors and Zn(II)Pcs, we show that formate is also readily attached to Mn(II), Mg(II) and Co(II)Pcs. However, for the Co(II)Pc secondary reactions can be observed. Upon collision-induced dissociation (CID), Zn(II)Por/Pc·formate supramolecular complexes can undergo the loss of CO2 in combination with transfer of a hydride anion (H(-)) to the zinc metal center. Further dissociation leads to electron transfer and hydrogen atom loss, generating a route to the radical anion of the Zn(II)Por/Pc without the need for electrochemical reduction, although the Zn(II)Por/Pc may have a too low electron affinity to allow electron transfer directly from the formate anion. In addition to single Por molecules, multi Por arrays were successfully analyzed by this method. In this case, multiple addition of formate occurs, giving rise to multiply charged species. In these multi Por arrays, complexation of the formate anion occurs by two surrounding Por units (sandwich). Therefore, the maximum attainment of formate anions in these arrays corresponds to the number of such sandwich complexes rather than the number of porphyrin moieties. The same bonding motif leads to dimers of the composition [(Zn(II)Por/Pc)2·HCOO](-). In these, the formate anion can act as a structural probe, allowing the distinction of isomeric ions with the formate bridging two macrocycles or being attached to a dimer of directly connected macrocycles.

Spectral characterization, cyclic voltammetry, morphology, biological activities and DNA cleaving studies of amino acid Schiff base metal(II) complexes

NASA Astrophysics Data System (ADS)

Neelakantan, M. A.; Rusalraj, F.; Dharmaraja, J.; Johnsonraja, S.; Jeyakumar, T.; Sankaranarayana Pillai, M.

2008-12-01

Metal complexes are synthesized with Schiff bases derived from o-phthalaldehyde (opa) and amino acids viz., glycine (gly) L-alanine (ala), L-phenylalanine (pal). Metal ions coordinate in a tetradentate or hexadentate manner with these N 2O 2 donor ligands, which are characterized by elemental analysis, molar conductance, magnetic moments, IR, electronic, 1H NMR and EPR spectral studies. The elemental analysis suggests the stoichiometry to be 1:1 (metal:ligand). Based on EPR studies, spin-Hamiltonian and bonding parameters have been calculated. The g-values calculated for copper complexes at 300 K and in frozen DMSO (77 K) indicate the presence of the unpaired electron in the d orbital. The evaluated metal-ligand bonding parameters showed strong in-plane σ- and π-bonding. X-ray diffraction (XRD) and scanning electron micrography (SEM) analysis provide the crystalline nature and the morphology of the metal complexes. The cyclic voltammograms of the Cu(II)/Mn(II)/VO(II) complexes investigated in DMSO solution exhibit metal centered electroactivity in the potential range -1.5 to +1.5 V. The electrochemical data obtained for Cu(II) complexes explains the change of structural arrangement of the ligand around Cu(II) ions. The biological activity of the complexes has been tested on eight bacteria and three fungi. Cu(II) and Ni(II) complexes show an increased activity in comparison to the controls. The metal complexes of opapal Schiff base were evaluated for their DNA cleaving activities with calf-thymus DNA (CT DNA) under aerobic conditions. Cu(II) and VO(II) complexes show more pronounced activity in presence of the oxidant.

Synthesis and characterization of hydroxyapatite nanoparticles impregnated on apple pomace to enhanced adsorption of Pb(II), Cd(II), and Ni(II) ions from aqueous solution.

PubMed

Chand, Piar; Pakade, Yogesh B

2015-07-01

Hydroxyapatite nanoparticles were synthesized, characterized, and impregnated onto apple pomace surface (HANP@AP) for efficient removal of Pb(II), Cd(II), and Ni(II) ions from water. HANP@AP was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD), and surface area analysis. Batch sorption studies were carried out to investigate the influence of different parameters as amount of dose (g), pH, time (min), and initial concentration (mg L(-1)) on adsorption process. Experimental kinetic data followed pseudo-second-order model and equilibrium data well fitted to Langmuir adsorption model with maximum adsorption capacities of 303, 250, and 100 mg g(-1) for Pb(II), Cd(II), and Ni(II) ions, respectively. Competitive adsorption of Pb(II), Cd(II), and Ni(II) ions in presences of each other was studied to evaluate the removal efficiency of HANP@AP against multi metal-loaded water. HANP@AP was successfully applied to real industrial wastewater with 100 % removal of all three metal ions even at high concentration. HANP@AP could be recycled for four, four, and three cycles in case of Pb(II), Cd(II) and Ni(II), respectively. The study showed that HANP@AP is fast, cost effective, and environmental friendly adsorbent for removal of Pb(II), Cd(II), and Ni(II) ions from real industrial wastewater.

In Situ D-periodic Molecular Structure of Type II Collagen

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antipova, Olga; Orgel, Joseph P.R.O.

Collagens are essential components of extracellular matrices in multicellular animals. Fibrillar type II collagen is the most prominent component of articular cartilage and other cartilage-like tissues such as notochord. Its in situ macromolecular and packing structures have not been fully characterized, but an understanding of these attributes may help reveal mechanisms of tissue assembly and degradation (as in osteo- and rheumatoid arthritis). In some tissues such as lamprey notochord, the collagen fibrillar organization is naturally crystalline and may be studied by x-ray diffraction. We used diffraction data from native and derivative notochord tissue samples to solve the axial, D-periodic structuremore » of type II collagen via multiple isomorphous replacement. The electron density maps and heavy atom data revealed the conformation of the nonhelical telopeptides and the overall D-periodic structure of collagen type II in native tissues, data that were further supported by structure prediction and transmission electron microscopy. These results help to explain the observed differences in collagen type I and type II fibrillar architecture and indicate the collagen type II cross-link organization, which is crucial for fibrillogenesis. Transmission electron microscopy data show the close relationship between lamprey and mammalian collagen fibrils, even though the respective larger scale tissue architecture differs.« less

Quasiparticle Scattering in Type-II Weyl semimetal MoTe₂.

PubMed

Lin, Chun-Liang; Arafune, Ryuichi; Minamitani, Emi; Kawai, Maki; Takagi, Noriaki

2018-01-30

The electronic structure of type-II Weyl semimetal molybdenum ditelluride (MoTe₂) is studied by using scanning tunneling microscopy and density functional theory calculations. Through measuring energy-dependent quasiparticle interference (QPI) patterns with a cryogenic scanning tunneling microscope, several characteristic features are found in the QPI patterns. Two of them arise from the Weyl semimetal nature; one is the topological Fermi arc surface state and the other can be assigned to be a Weyl point. The remaining structures are derived from the scatterings relevant to the bulk electronic states. The findings lead to thorough understanding of the topological electronic structure of type-II Weyl semimetal MoTe₂. © 2018 IOP Publishing Ltd.

The electronic spectra and the structures of the individual copper(II) chloride and bromide complexes in acetonitrile according to steady-state absorption spectroscopy and DFT/TD-DFT calculations

NASA Astrophysics Data System (ADS)

Olshin, Pavel K.; Myasnikova, Olesya S.; Kashina, Maria V.; Gorbunov, Artem O.; Bogachev, Nikita A.; Kompanets, Viktor O.; Chekalin, Sergey V.; Pulkin, Sergey A.; Kochemirovsky, Vladimir A.; Skripkin, Mikhail Yu.; Mereshchenko, Andrey S.

2018-03-01

The results of spectrophotometric study and quantum chemical calculations for copper(II) chloro- and bromocomplexes in acetonitrile are reported. Electronic spectra of the individual copper(II) halide complexes were obtained in a wide spectral range 200-2200 nm. Stability constants of the individual copper(II) halide complexes in acetonitrile were calculated: log β1 = 8.5, log β2 = 15.6, log β3 = 22.5, log β4 = 25.7 for [CuCln]2-n and log β1 = 17.0, log β2 = 24.6, log β3 = 28.1, log β4 = 30.4 for [CuBrn]2-n. Structures of the studied complexes were optimized and electronic spectra were simulated using DFT and TD-DFT methodologies, respectively. According to the calculations, the more is the number of halide ligands the less is coordination number of copper ion.

Synthesis, characterization and investigation of electrochemical and spectroelectrochemical properties of non-peripherally tetra-5-methyl-1,3,4-thiadiazole substituted copper(II) iron(II) and oxo-titanium (IV) phthalocyanines

NASA Astrophysics Data System (ADS)

Demirbaş, Ümit; Akyüz, Duygu; Akçay, Hakkı Türker; Barut, Burak; Koca, Atıf; Kantekin, Halit

2017-09-01

In this study novel substituted phthalonitrile (3) and non-peripherally tetra 5-Methyl-1,3,4-thiadiazole substituted copper(II) (4), iron(II) (5) and oxo-titanium (IV) (6) phthalocyanines were synthesized. These novel compounds were fully characterized by FT-IR, 1H NMR, UV-vis and MALDI-TOF mass spectroscopic techniques. Voltammetric and in situ spectroelectrochemical measurements were performed for metallo-phthalocyanines (4-6). TiIVOPc and FeIIPc showed metal-based and ligand-based electron transfer reactions while CuIIPc shows only ligand-based electron transfer reaction. Voltammetric measurements indicated that the complexes have reversible, diffusion controlled and one-electron redox reactions. The assignments of the redox processes and color of the electrogenerated species of the complexes were determined with in-situ spectroelectrochemical and electrocolorimetric measurements. These measurements showed that the complexes can be used as the electrochromic materials for various display technologies.

21 CFR 1305.27 - Preservation of electronic orders.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 9 2013-04-01 2013-04-01 false Preservation of electronic orders. 1305.27 Section... II CONTROLLED SUBSTANCES Electronic Orders § 1305.27 Preservation of electronic orders. (a) A... two years. (c) If electronic order records are maintained on a central server, the records must be...

21 CFR 1305.27 - Preservation of electronic orders.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 9 2012-04-01 2012-04-01 false Preservation of electronic orders. 1305.27 Section... II CONTROLLED SUBSTANCES Electronic Orders § 1305.27 Preservation of electronic orders. (a) A... two years. (c) If electronic order records are maintained on a central server, the records must be...

21 CFR 1305.27 - Preservation of electronic orders.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 9 2011-04-01 2011-04-01 false Preservation of electronic orders. 1305.27 Section... II CONTROLLED SUBSTANCES Electronic Orders § 1305.27 Preservation of electronic orders. (a) A... two years. (c) If electronic order records are maintained on a central server, the records must be...

21 CFR 1305.27 - Preservation of electronic orders.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 9 2014-04-01 2014-04-01 false Preservation of electronic orders. 1305.27 Section... II CONTROLLED SUBSTANCES Electronic Orders § 1305.27 Preservation of electronic orders. (a) A... two years. (c) If electronic order records are maintained on a central server, the records must be...

21 CFR 1305.27 - Preservation of electronic orders.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Preservation of electronic orders. 1305.27 Section... II CONTROLLED SUBSTANCES Electronic Orders § 1305.27 Preservation of electronic orders. (a) A... two years. (c) If electronic order records are maintained on a central server, the records must be...

Biotic stress induced demolition of thylakoid structure and loss in photoelectron transport of chloroplasts in papaya leaves.

PubMed

Nanda, Rashmi Madhumita; Biswal, Basanti

2008-04-01

Papaya mosaic virus (PMV) causes severe mosaic symptoms in the papaya (Carica papaya L.) leaves. The PMV-induced alterations in photosystem II (PS II) structure and photochemical functions were probed. An increase in chlorophyll a (Chl a) fluorescence polarization suggests pathogen-induced transformation of thylakoid membrane to a gel phase. This transformation in physical state of thylakoid membrane may result in alteration in topology of pigments on pigment-binding proteins as reflected in pathogen-induced loss in the efficiency of energy transfer from carotenoids to chlorophylls. The fast Chl a fluorescence induction kinetics of healthy and PMV-infected plants by F(O)-F(J)-F(I)-F(P) transients revealed pathogen-induced perturbation on PS II acceptor side electron transfer equilibrium between Q(A) and Q(B) and in the pool size of electron transport acceptors. Pathogen-induced loss in photosynthetic pigments, changes in thylakoid structure and decrease in the ratio of F(V)/F(M) (photochemical potential of PS II) further correlate with the loss in photoelectron transport of PS II as probed by 2,6-dichlorophenol indophenol (DCPIP)-Hill reaction. Restoration of the loss by 1,5-diphenyl carbazide (DPC), an exogenous electron donor, that donates electron directly to reaction centre II bypassing the oxygen evolving system (OES), leads towards the conclusion that OES is one of the major targets of biotic stress. Further, the data suggest that chlorophyll fluorescence could be used as a non-invasive handy tool to assess the loss in photosynthetic efficiency and symptom severity in infected green tissues vis-a-vis the healthy ones.

New Rh 2 (II,II) Architecture for the Catalytic Reduction of H +

DOE PAGES

White, Travis A.; Witt, Suzanne E.; Li, Zhanyong; ...

2015-09-25

Formamidinate-bridged Rh 2 II,II complexes containing diimine ligands of the formula cis-[Rh 2 II,II(μ-DTolF) 2(NN) 2] 2+ (Rh 2-NN 2), where DTolF = p-ditolylformamidinate and NN = dppn (benzo[i]dipyrido[3,2-a:2',3'-h]quinoxaline), dppz (dipyrido[3,2-a:2',3'-c]phenazine), and phen (1,10-phenanthroline), electrocatalytically reduce H + to H 2 in DMF solutions containing CH 3COOH at a glassy carbon electrode. Cathodic scans in the absence of acid display a Rh III,II/II,II reduction at -0.90 V vs Fc +/Fc followed by NN 0/– reduction at -1.13, -1.36, and -1.65 V for Rh 2-dppn 2, Rh 2-dppz 2, and Rh 2-phen 2, respectively. Upon the addition of acid, Rh 2-dppnmore » 2 and Rh 2-dppz 2 undergo reduction–protonation–reduction at each pyrazine-containing NN ligand prior to the Rh 2 II,II/II,I reduction. The Rh 2 II,I species is thus protonated at one of the metal centers, resulting in the formation of the corresponding Rh 2 II,III-hydride. In the case of Rh 2-phen 2, the reduction of the phen ligand is followed by intramolecular electron transfer to the Rh 2 II,II core in the presence of protons to form a Rh 2 II,III-hydride species. Further reduction and protonation at the Rh 2 core for all three complexes rapidly catalyzes H 2 formation with varied calculated turnover frequencies (TOF) and overpotential values (η): 2.6 × 10 4 s –1 and 0.56 V for Rh 2-dppn, 2.8 × 10 4 s –1 and 0.50 V for Rh 2-dppz 2, and 5.9 × 10 4 s –1 and 0.64 V for Rh 2-phen 2. Bulk electrolysis confirmed H 2 formation, and further CH 3COOH addition regenerates H 2 production, attesting to the robust nature of the architecture. The cis-[Rh 2 II,II(μ-DTolF) 2(NN) 2] 2+ architecture benefits by combining electron-rich formamidinate bridges, a redox-active Rh 2 II,II core, and electron-accepting NN diimine ligands to allow for the electrocatalysis of H + substrate to H 2 fuel.« less

The Argonne CDF Group

Science.gov Websites

calorimeter, Shower Max., Preshower, Crack Chambers (1979-present) Run II Upgrade: Front end electronics (QIE , Preshower electronics and DAQ Support for Level-2 electron and photon triggers (RECES and ISO) Deputy Head

Comparison of LIDAR system performance for alternative single-mode receiver architectures: modeling and experimental validation

NASA Astrophysics Data System (ADS)

Toliver, Paul; Ozdur, Ibrahim; Agarwal, Anjali; Woodward, T. K.

2013-05-01

In this paper, we describe a detailed performance comparison of alternative single-pixel, single-mode LIDAR architectures including (i) linear-mode APD-based direct-detection, (ii) optically-preamplified PIN receiver, (iii) PINbased coherent-detection, and (iv) Geiger-mode single-photon-APD counting. Such a comparison is useful when considering next-generation LIDAR on a chip, which would allow one to leverage extensive waveguide-based structures and processing elements developed for telecom and apply them to small form-factor sensing applications. Models of four LIDAR transmit and receive systems are described in detail, which include not only the dominant sources of receiver noise commonly assumed in each of the four detection limits, but also additional noise terms present in realistic implementations. These receiver models are validated through the analysis of detection statistics collected from an experimental LIDAR testbed. The receiver is reconfigurable into four modes of operation, while transmit waveforms and channel characteristics are held constant. The use of a diffuse hard target highlights the importance of including speckle noise terms in the overall system analysis. All measurements are done at 1550 nm, which offers multiple system advantages including less stringent eye safety requirements and compatibility with available telecom components, optical amplification, and photonic integration. Ultimately, the experimentally-validated detection statistics can be used as part of an end-to-end system model for projecting rate, range, and resolution performance limits and tradeoffs of alternative integrated LIDAR architectures.

78 FR 24061 - Minimum Technical Standards for Class II Gaming Systems and Equipment

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-24

... Register that established technical standards for ensuring the integrity of electronic Class II games and aids. 73 FR 60508, Oct. 10, 2008. The technical standards were designed to assist tribal gaming... Class II gaming systems. The standards did not classify which games were Class II games and which games...

TRANSFORMATION OF NITROSOBENZENES AND HYDROXYLANILINES BY FE II SPECIES: ELUCIDATION OF MECHANISM, EFFECT OF FERRIC OXIDES AND PH

EPA Science Inventory

Nitrosobenzenes, the first intermediates in the reduction of nitrobenzenes, were reduced by Fe(II) solutions as well as by Fe(II)-treated goethite suspensions (Fe(II)/G). Results indicate a reactivity trend in which electron-withdrawing groups in the para position increased the ...

Electrochemical studies of DNA interaction and antimicrobial activities of MnII, FeIII, CoII and NiII Schiff base tetraazamacrocyclic complexes

NASA Astrophysics Data System (ADS)

Kumar, Anuj; Vashistha, Vinod Kumar; Tevatia, Prashant; Singh, Randhir

2017-04-01

Tetraazamacrocyclic complexes of MnII, FeIII, CoII and NiII have been synthesized by template method. These tetraazamacrocycles have been analyzed with various techniques like molar conductance, IR, UV-vis, mass spectral and cyclic voltammetric studies. On the basis of all these studies, octahedral geometry has been assigned to these tetraazamacrocyclic complexes. The DNA binding properties of these macrocyclic complexes have been investigated by electronic absorption spectra, fluorescence spectra, cyclic voltammetric and differential pulse voltammetric studies. The cyclic voltammetric data showed that ipc and ipa were effectively decreased in the presence of calf thymus DNA, which is a strong evidence for the interaction of these macrocyclic complexes with the calf thymus DNA (ct-DNA). The heterogeneous electron transfer rate constant found in the order: KCoII > KNiII > KMnII which indicates that CoII macrocyclic complex has formed a strong intercalated intermediate. The Stern-Volmer quenching constant (KSV) and voltammetric binding constant were found in the order KSV(CoII) > KSV(NiII) > KSV(MnII) and K+(CoII) > K+(NiII) > K+(MnII) which shows that CoII macrocyclic complex exhibits the high interaction affinity towards ct-DNA by the intercalation binding. Biological studies of the macrocyclic complexes compared with the standard drug like Gentamycin, have shown antibacterial activities against E. coli, P. aeruginosa, B. cereus, S. aureus and antifungal activity against C. albicans.

Evolution of Electron Transport Chains During the Anaerobic to Aerobic Transition on Early Earth

NASA Astrophysics Data System (ADS)

Sepúlveda, R.; Ortiz, R.; Holmes, D. S.

2015-12-01

Sepulveda, R., Ortiz R. and Holmes DS. Center for Bioinformatics and Genome Biology, Fundacion Ciencia y Vida, and Facultad de Ciencias Biologicas, Universidad Andres Bello, Santiago, Chile.According to several models, life emerged on earth in an anoxic environment where oxygen was not available as a terminal electron acceptor for energy generating reactions. After the Great Oxidation Event (GOE) about 2.4 billion years ago, or perhaps even before the GOE, oxygen became the most widespread and efficient terminal electron acceptor and was accompanied by the evolution of a number of redox proteins that could deliver electrons to reduce oxygen to water. Where did these proteins come from? One hypothesis is that they evolved by the neofunctionalization of previously existing redox proteins that had been used in anaerobic conditions as terminal electron donors to reduce compounds such as perchlorate, nitric oxide or iron. We have used a number of bioinformatic tools to explore a large number of genomes looking for discernable signals of such redeployment of function. A Perl pipeline was designed to detect sequence similarity, conserved gene context, remote homology detection, identification of domains and functional evolution of electron carrier proteins from extreme acidophiles, including the small blue copper protein rusticyanin (involved in FeII oxidation), cytochrome oxidase subunit II and quinol-dependent nitric oxide reductase (qNOR). The protein folds and copper binding sites of rusticyanin are conserved in cytochrome oxidase aa3 subunit II, a protein complex that is responsible for the final passage of electrons to reduce oxygen. Therefore, we hypothesize that rusticyanin, cytochrome oxidase II and qNOR are evolutionarily related. Acknowledgments: Fondecyt 1130683.

Field-Effect Transistor-Integration with TiO2 Nanoparticles for Sensing of Cardiac Troponin I Biomarker.

PubMed

Arshad, M K Md; Adzhri, R; Fathil, M F M; Gopinath, Subash C B; N M, Nuzaihan M

2018-08-01

The development of electrical biosensor towards device miniaturization in order to achieve better sensitivity with enhanced electrical signal has certain limitations especially complexity in fabrication process and costs. In this paper, an alternative technique with minor modification in the device structure is presented for signal amplification by implementing ambipolar conduction in the biosensor itself. We demonstrated the field-effect transistor (FET)-based biosensor coupled back-gate for attaining a higher sensitivity with the detection of lower target abundance. To utilize the coupled back-gate as a pre-amplifier, silicon-on-insulator wafer with thicknesses of top-silicon and buried oxide (BOX) layers of 70 nm and 145 nm, respectively were desired. Titanium dioxide (TiO2) nanomaterial was deposited using sol-gel method on the channel which acts as a transducer. Surface functionalization on TiO2 thin film allowed an effective immobilization of anti-cardiac troponin I antibody to interact cardiac troponin I (cTnI). Binding events at each step was validated by X-ray photoelectron spectroscopy (XPS) analysis. Further, electrical characterization (Id-Vd) confirms the potentiality of FET-based biosensor to detect cTnI (represents acute myocardial infarction disease) with the concentration ranges from 10 μg/ml down to 1 fg/ml. The sensitivity of 459.2 nA (g/ml)-1 and lower detection limit of 1 fg/ml were achieved at Vbg = -5 V and Vd = 5 V. The designed device demonstrates its ability to detect lower level of cTnI with pre-amplified electrical signal by back-gate biasing.

Highly sensitive lidar with a thumb-sized sensor-head built using an optical fiber preamplifier

NASA Astrophysics Data System (ADS)

Inoue, Daisuke; Ichikawa, Tadashi; Matsubara, Hiroyuki; Mao, Xueon; Maeda, Mitsutoshi; Nagashima, Chie; Kagami, Manabu

2011-06-01

We developed a LIDAR system with a sensor head as small as 22 cc, in spite of the inclusion of a scanning mechanism. This LIDAR system not only has a small body, but is also highly sensitive. Our LIDAR system is based on time-of-flight measurements, and it incorporates an optical fiber. The main feature of our system is the utilization of optical amplifiers for both the transmitter and the receiver, and the optical amplifiers enabled us to exceed the detection limit of thermal noise. In conventional LIDAR systems the detection limit is determined by thermal noise, because the avalanche photo-diodes (APD) and trans-impedance amplifiers (TIA) that they use detect the received signals directly. In the case of our LIDAR system, received signal is amplified by an optical fiber amplifier in front of the photo diode and the TIA. Therefore, our LIDAR system can boost the signal level before the weak incoming signal is depleted by thermal noise. There are conditions under which the noise figure for the combination of an optical fiber amplifier and a photo diode is superior to the noise figure for an avalanche photo diode. We optimized the gain of the optical fiber amplifier and TIA in our LIDAR system such that it is capable of detecting a single photon. As a result, the detection limit of our LIDAR system is determined by shot noise. This small and highly sensitive measurement technology shows great potential for use in LIDAR with an optical preamplifier.

Observation of Fermi arcs in the type-II Weyl semimetal candidate WTe 2

DOE PAGES

Wu, Yun; Mou, Daixiang; Jo, Na Hyun; ...

2016-09-14

We use ultrahigh resolution, tunable, vacuum ultraviolet laser angle-resolved photoemission spectroscopy (ARPES) to study the electronic properties of WTe 2, a material that was predicted to be a type-II Weyl semimetal. The Weyl fermion states in WTe 2 were proposed to emerge at the crossing points of electron and hole pockets, and Fermi arcs connecting electron and hole pockets would be visible in the spectral function on (001) surface. Here we report the observation of such Fermi arcs in WTe 2 confirming the theoretical predictions. This provides strong evidence for type-II Weyl semimetallic states in WTe 2. Here, we alsomore » find that trivial and topological domains coexist on the same surface of the sample due to the presence of inhomogeneous strain detected by scanning electron microscopy data. This is in agreement with the theoretical prediction that strain can drive this system from topological Weyl to trivial semimetal. WTe 2 therefore provides a tunable playground for studying exotic topological quantum effects.« less

A bioinspired redox relay that mimics radical interactions of the Tyr-His pairs of photosystem II

NASA Astrophysics Data System (ADS)

Megiatto, Jackson D., Jr.; Méndez-Hernández, Dalvin D.; Tejeda-Ferrari, Marely E.; Teillout, Anne-Lucie; Llansola-Portolés, Manuel J.; Kodis, Gerdenis; Poluektov, Oleg G.; Rajh, Tijana; Mujica, Vladimiro; Groy, Thomas L.; Gust, Devens; Moore, Thomas A.; Moore, Ana L.

2014-05-01

In water-oxidizing photosynthetic organisms, light absorption generates a powerfully oxidizing chlorophyll complex (P680•+) in the photosystem II reaction centre. This is reduced via an electron transfer pathway from the manganese-containing water-oxidizing catalyst, which includes an electron transfer relay comprising a tyrosine (Tyr)-histidine (His) pair that features a hydrogen bond between a phenol group and an imidazole group. By rapidly reducing P680•+, the relay is thought to mitigate recombination reactions, thereby ensuring a high quantum yield of water oxidation. Here, we show that an artificial reaction centre that features a benzimidazole-phenol model of the Tyr-His pair mimics both the short-internal hydrogen bond in photosystem II and, using electron paramagnetic resonance spectroscopy, the thermal relaxation that accompanies proton-coupled electron transfer. Although this artificial system is much less complex than the natural one, theory suggests that it captures the essential features that are important in the function of the relay.

Observation of Fermi arcs in the type-II Weyl semimetal candidate WTe 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Yun; Mou, Daixiang; Jo, Na Hyun

We use ultrahigh resolution, tunable, vacuum ultraviolet laser angle-resolved photoemission spectroscopy (ARPES) to study the electronic properties of WTe 2, a material that was predicted to be a type-II Weyl semimetal. The Weyl fermion states in WTe 2 were proposed to emerge at the crossing points of electron and hole pockets, and Fermi arcs connecting electron and hole pockets would be visible in the spectral function on (001) surface. Here we report the observation of such Fermi arcs in WTe 2 confirming the theoretical predictions. This provides strong evidence for type-II Weyl semimetallic states in WTe 2. Here, we alsomore » find that trivial and topological domains coexist on the same surface of the sample due to the presence of inhomogeneous strain detected by scanning electron microscopy data. This is in agreement with the theoretical prediction that strain can drive this system from topological Weyl to trivial semimetal. WTe 2 therefore provides a tunable playground for studying exotic topological quantum effects.« less

THE DISCREPANT KINEMATICS OF ORLs AND CELs IN NGC 7009 AS A FUNCTION OF IONIZATION STRUCTURE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Richer, Michael G.; Georgiev, Leonid; Torres-Peimbert, Silvia

2013-08-20

We present spatially and velocity-resolved echelle spectroscopy for NGC 7009 obtained with the UVES spectrograph at the European Southern Observatory's Very Large Telescope. Our objective is to analyze the kinematics of emission lines excited by recombination and collisions with electrons to determine whether similarities or differences could be useful in elucidating the well-known abundance discrepancy derived from them. We construct position-velocity maps for recombination, fluorescence, charge transfer, and collisionally excited lines. We find a plasma component emitting in the C II, N II, O II, and Ne II recombination lines whose kinematics are discrepant: they are incompatible with the ionizationmore » structure derived from all other evidence and the kinematics derived from all of these lines are unexpectedly very similar. We find direct evidence for a recombination contribution to [N II] {lambda}5755. Once taken into account, the electron temperatures from [N II], [O III], and [Ne III] agree at a given position and velocity. The electron densities derived from [O II] and [Ar IV] are consistent with direct imaging and the distribution of hydrogen emission. The kinematics of the C II, N II, O II, and Ne II lines does not coincide with the kinematics of the [O III] and [Ne III] forbidden emission, indicating that there is an additional plasma component to the recombination emission that arises from a different volume from that giving rise to the forbidden emission from the parent ions within NGC 7009. Thus, the chemical abundances derived from either type of line are correct only for the plasma component from which they arise. Apart from [N II] {lambda}5755, we find no anomaly with the forbidden lines usually used to determine chemical abundances in ionized nebulae, so the abundances derived from them should be reliable for the medium from which they arise.« less

A portable cadmium telluride multidetector probe for cardiac function monitoring

NASA Astrophysics Data System (ADS)

Arntz, Y.; Chambron, J.; Dumitresco, B.; Eclancher, B.; Prat, V.

1999-06-01

A new nuclear stethoscope based on a matrix of small CdTe semiconductor detectors has been developed for studying the cardiac performance by gamma ventriculography at the equilibrium, in rest and stress conditions, in the early and recovery phases of the coronary disease and to follow the long-term therapy. The light-weight probe consists of an array of 64 detectors 5×5×2 mm grouped in 16 independent units in a lead shielded aluminum box including 16 preamplifiers. The probe is connected to an electronic box containing DC power supply, 16 channel amplifiers, discriminators and counters, two analog-triggering ECG channels, and interface to a PC. The left ventricle activity is, preferentially, detected by using a low-resolution matching convergent collimator. A physical evaluation of the probe has been performed, both with static tests and dynamically with a hydraulic home-built model of beating heart ventricle paced by a rhythm simulator. The sum of the 16 detectors activity provided a radiocardiogram (RCG) which well depicted the filling and ejection of the cardiac beats, allowing to compare the clinically relevant parameters of the cardiac performance, proportional variables of the stroke volume (SV), ejection fraction (EF) and ventricular flow-rate with the known absolute values programmed on the model. The portable system is now in operation for clinical assessment of cardiac patients.

Wireless recording systems: from noninvasive EEG-NIRS to invasive EEG devices.

PubMed

Sawan, Mohamad; Salam, Muhammad T; Le Lan, Jérôme; Kassab, Amal; Gelinas, Sébastien; Vannasing, Phetsamone; Lesage, Frédéric; Lassonde, Maryse; Nguyen, Dang K

2013-04-01

In this paper, we present the design and implementation of a wireless wearable electronic system dedicated to remote data recording for brain monitoring. The reported wireless recording system is used for a) simultaneous near-infrared spectrometry (NIRS) and scalp electro-encephalography (EEG) for noninvasive monitoring and b) intracerebral EEG (icEEG) for invasive monitoring. Bluetooth and dual radio links were introduced for these recordings. The Bluetooth-based device was embedded in a noninvasive multichannel EEG-NIRS system for easy portability and long-term monitoring. On the other hand, the 32-channel implantable recording device offers 24-bit resolution, tunable features, and a sampling frequency up to 2 kHz per channel. The analog front-end preamplifier presents low input-referred noise of 5 μ VRMS and a signal-to-noise ratio of 112 dB. The communication link is implemented using a dual-band radio frequency transceiver offering a half-duplex 800 kb/s data rate, 16.5 mW power consumption and less than 10(-10) post-correction Bit-Error Rate (BER). The designed system can be accessed and controlled by a computer with a user-friendly graphical interface. The proposed wireless implantable recording device was tested in vitro using real icEEG signals from two patients with refractory epilepsy. The wirelessly recorded signals were compared to the original signals recorded using wired-connection, and measured normalized root-mean square deviation was under 2%.

Spaced-based search coil magnetometers

NASA Astrophysics Data System (ADS)

Hospodarsky, George B.

2016-12-01

Search coil magnetometers are one of the primary tools used to study the magnetic component of low-frequency electromagnetic waves in space. Their relatively small size, mass, and power consumption, coupled with a good frequency range and sensitivity, make them ideal for spaceflight applications. The basic design of a search coil magnetometer consists of many thousands of turns of wire wound on a high permeability core. When a time-varying magnetic field passes through the coil, a time-varying voltage is induced due to Faraday's law of magnetic induction. The output of the coil is usually attached to a preamplifier, which amplifies the induced voltage and conditions the signal for transmission to the main electronics (usually a low-frequency radio receiver). Search coil magnetometers are usually used in conjunction with electric field antenna to measure electromagnetic plasma waves in the frequency range of a few hertz to a few tens of kilohertzs. Search coil magnetometers are used to determine the properties of waves, such as comparing the relative electric and magnetic field amplitudes of the waves, or to investigate wave propagation parameters, such as Poynting flux and wave normal vectors. On a spinning spacecraft, they are also sometimes used to determine the background magnetic field. This paper presents some of the basic design criteria of search coil magnetometers and discusses design characteristics of sensors flown on a number of spacecraft.

Characterization of Pixelated Cadmium-Zinc-Telluride Detectors for Astrophysical Applications

NASA Technical Reports Server (NTRS)

Gaskin, Jessica; Sharma, Dharma; Ramsey, Brian; Seller, Paul

2003-01-01

Comparisons of charge sharing and charge loss measurements between two pixelated Cadmium-Zinc-Telluride (CdZnTe) detectors are discussed. These properties along with the detector geometry help to define the limiting energy resolution and spatial resolution of the detector in question. The first detector consists of a 1-mm-thick piece of CdZnTe sputtered with a 4x4 array of pixels with pixel pitch of 750 microns (inter-pixel gap is 100 microns). Signal readout is via discrete ultra-low-noise preamplifiers, one for each of the 16 pixels. The second detector consists of a 2-mm-thick piece of CdZnTe sputtered with a 16x16 array of pixels with a pixel pitch of 300 microns (inter-pixel gap is 50 microns). This crystal is bonded to a custom-built readout chip (ASIC) providing all front-end electronics to each of the 256 independent pixels. These detectors act as precursors to that which will be used at the focal plane of the High Energy Replicated Optics (HERO) telescope currently being developed at Marshall Space Flight Center. With a telescope focal length of 6 meters, the detector needs to have a spatial resolution of around 200 microns in order to take full advantage of the HERO angular resolution. We discuss to what degree charge sharing will degrade energy resolution but will improve our spatial resolution through position interpolation.

Development of the Focal Plane Detection System for the Future Gas-Filled Separator at the Cyclotron Institute

NASA Astrophysics Data System (ADS)

Bertelsen, Erin; Mayorov, Dmitriy; Folden, Charles ``Cody'', III

2015-10-01

A focal plane detection system is being developed for use with the gas-filled separator previously known as SASSYER (Small Angle Separator System at Yale for Evaporation Residues) that will be installed at the Cyclotron Institute at Texas A&M University. This system will be used to study heavy (Z >= 90) elements and features two 60×40 strip double-sided silicon detectors (DSSDs) and accompanying multiplexing read-out electronics. The DSSDs cover an area of 120×40 mm2 and are read-out by fourteen 16-channel multiplexers (Mesytec MUX-16) that perform the function of a preamplifier, shaper, and leading-edge discriminator in one unit. The multiplexers are controlled by four ``MUX drivers,'' each of which serves as a signal bus for multiple MUX-16 boards. The system allows a single 16-channel ADC to read the combined 200 strips of both DSSDs. A four peak source composed of 148Gd, 239Pu, 241Am, and 244Cm was used to characterize the performance of the system, with a preliminary energy resolution of ~ 60 keV measured for the 241Am alphas. This contribution will discuss the work performed in assembly of the test setup, optimization and performance check of the multiplexers, and the preliminary energy and position data collected with the α-source. Present address: Los Alamos National Laboratory, Los Alamos, NM 87545.

Development of a Cryostat to Characterize Nano-scale Superconducting Quantum Interference Devices

NASA Astrophysics Data System (ADS)

Longo, Mathew; Matheny, Matthew; Knudsen, Jasmine

2016-03-01

We have designed and constructed a low-noise vacuum cryostat to be used for the characterization of nano-scale superconducting quantum interference devices (SQUIDs). Such devices are very sensitive to magnetic fields and can measure changes in flux on the order of a single electron magnetic moment. As a part of the design process, we calculated the separation required between the cryogenic preamplifier and superconducting magnet, including a high-permeability magnetic shield, using a finite-element model of the apparatus. The cryostat comprises a vacuum cross at room temperature for filtered DC and shielded RF electrical connections, a thin-wall stainless steel support tube, a taper-sealed cryogenic vacuum can, and internal mechanical support and wiring for the nanoSQUID. The Dewar is modified with a room-temperature flange with a sliding seal for the cryostat. The flange supports the superconducting 3 Tesla magnet and thermometry wiring. Upon completion of the cryostat fabrication and Dewar modifications, operation of the nanoSQUIDs as transported from our collaborator's laboratory in Israel will be confirmed, as the lead forming the SQUID is sensitive to oxidation and the SQUIDs must be shipped in a vacuum container. After operation of the nanoSQUIDs is confirmed, the primary work of characterizing their high-speed properties will begin. This will include looking at the measurement of relaxation oscillations at high bandwidth in comparison to the theoretical predictions of the current model.

Fermilab Recycler Ring BPM Upgrade Based on Digital Receiver Technology

NASA Astrophysics Data System (ADS)

Webber, R.; Crisp, J.; Prieto, P.; Voy, D.; Briegel, C.; McClure, C.; West, R.; Pordes, S.; Mengel, M.

2004-11-01

Electronics for the 237 BPMs in the Fermilab Recycler Ring have been upgraded from a log-amplifier based system to a commercially produced digitizer-digital down converter based system. The hardware consists of a pre-amplifier connected to a split-plate BPM, an analog differential receiver-filter module and an 8-channel 80-MHz digital down converter VME board. The system produces position and intensity with a dynamic range of 30 dB and a resolution of ±10 microns. The position measurements are made on 2.5-MHz bunched beam and barrier buckets of the un-bunched beam. The digital receiver system operates in one of six different signal processing modes that include 2.5-MHz average, 2.5-MHz bunch-by-bunch, 2.5-MHz narrow band, unbunched average, un-bunched head/tail and 89-kHz narrow band. Receiver data is acquired on any of up to sixteen clock events related to Recycler beam transfers and other machine activities. Data from the digital receiver board are transferred to the front-end CPU for position and intensity computation on an on-demand basis through the VME bus. Data buffers are maintained for each of the acquisition events and support flash, closed orbit and turn-by-turn measurements. A calibration system provides evaluation of the BPM signal path and application programs.

Assessment of wavelength-dependent parameters of photosynthetic electron transport with a new type of multi-color PAM chlorophyll fluorometer.

PubMed

Schreiber, Ulrich; Klughammer, Christof; Kolbowski, Jörg

2012-09-01

Technical features of a novel multi-color pulse amplitude modulation (PAM) chlorophyll fluorometer as well as the applied methodology and some typical examples of its practical application with suspensions of Chlorella vulgaris and Synechocystis PCC 6803 are presented. The multi-color PAM provides six colors of pulse-modulated measuring light (peak-wavelengths at 400, 440, 480, 540, 590, and 625 nm) and six colors of actinic light (AL), peaking at 440, 480, 540, 590, 625 and 420-640 nm (white). The AL can be used for continuous illumination, maximal intensity single-turnover pulses, high intensity multiple-turnover pulses, and saturation pulses. In addition, far-red light (peaking at 725 nm) is provided for preferential excitation of PS I. Analysis of the fast fluorescence rise kinetics in saturating light allows determination of the wavelength- and sample-specific functional absorption cross section of PS II, Sigma(II)(λ), with which the PS II turnover rate at a given incident photosynthetically active radiation (PAR) can be calculated. Sigma(II)(λ) is defined for a quasi-dark reference state, thus differing from σ(PSII) used in limnology and oceanography. Vastly different light response curves for Chlorella are obtained with light of different colors, when the usual PAR-scale is used. Based on Sigma(II)(λ) the PAR, in units of μmol quanta/(m(2) s), can be converted into PAR(II) (in units of PS II effective quanta/s) and a fluorescence-based electron transport rate ETR(II) = PAR(II) · Y(II)/Y(II)(max) can be defined. ETR(II) in contrast to rel.ETR qualifies for quantifying the absolute rate of electron transport in optically thin suspensions of unicellular algae and cyanobacteria. Plots of ETR(II) versus PAR(II) for Chlorella are almost identical using either 440 or 625 nm light. Photoinhibition data are presented suggesting that a lower value of ETR(II)(max) with 440 nm possibly reflects photodamage via absorption by the Mn-cluster of the oxygen-evolving complex.

Electronic transition moment for the B(2)II-X(2)II system of NO

NASA Technical Reports Server (NTRS)

Luque, Jorge; Crosley, David R.

1995-01-01

The upsilon' = 0-3 and 7 vibrational levels of the NO B(2)II state have been selectively excited by laser radiation. The fluorescence spectra together with calculated Franck-Condon factors and r-centroids have been used to evaluate the electronic transition moment. The results for upsilon' = 0-3 are in very good agreement with recent chemiluminescence measurements and ab initio calculations. Furthermore, the data from upsilon' = 7 have been used to extend the empirically determined moment to limits 1.23 and 1.78 A, improving agreement with experimentally determined lifetimes.

17 CFR 23.202 - Daily trading records.

Code of Federal Regulations, 2014 CFR

2014-04-01

..., instant messaging, chat rooms, electronic mail, mobile device, or other digital or electronic media. Such...; (ii) Moneys borrowed and moneys loaned; (iii) The daily calculation of the value of each outstanding... rooms, electronic mail, mobile device, or other digital or electronic media; (2) Reliable timing data...

17 CFR 23.202 - Daily trading records.

Code of Federal Regulations, 2013 CFR

2013-04-01

..., instant messaging, chat rooms, electronic mail, mobile device, or other digital or electronic media. Such...; (ii) Moneys borrowed and moneys loaned; (iii) The daily calculation of the value of each outstanding... rooms, electronic mail, mobile device, or other digital or electronic media; (2) Reliable timing data...

Spectrum simulation in DTSA-II.

PubMed

Ritchie, Nicholas W M

2009-10-01

Spectrum simulation is a useful practical and pedagogical tool. Particularly with complex samples or trace constituents, a simulation can help to understand the limits of the technique and the instrument parameters for the optimal measurement. DTSA-II, software for electron probe microanalysis, provides both easy to use and flexible tools for simulating common and less common sample geometries and materials. Analytical models based on (rhoz) curves provide quick simulations of simple samples. Monte Carlo models based on electron and X-ray transport provide more sophisticated models of arbitrarily complex samples. DTSA-II provides a broad range of simulation tools in a framework with many different interchangeable physical models. In addition, DTSA-II provides tools for visualizing, comparing, manipulating, and quantifying simulated and measured spectra.

Isolation, Characterization and Antitumour Propirties of the 1,2-Popylenediaminetetraacetate trans-Diaqua-Copper (II)

PubMed Central

Kamah, S.; Vilaplana, R.; Moreno, J.; Akdi, K.; García-Herdugo, G.

2000-01-01

A trans-diaquacomplex formed by copper(II) sulphate and the sequestering polyamminopolycarboxylic ligand 1,2-propylenediaminetetraacetic acid (PDTA) has been isolated and characterized by chemical analysis, titrimetry, FT-IR and electronic spectroscopy, Potentiometric and electronic measurements identified the ligand as tetradentate, two nitrogen and two oxygen atoms being bonded to the Cu(II) in planar positions. This octahedral monomeric soluble compound, is an unusual example of a copper (II) substance showing significant in vitro antitumour activity against the human ovarian tumour cells TG (ID50 = 2.29 μM at 48 h) and important in vivo antitumour activity against solid Sarcoma 180 with complete regression of the tumour at a dose of 12.5 mg/Kg body weight. PMID:18475948

Photosensitized H2 Production Using a Zinc Porphyrin-Substituted Protein, Platinum Nanoparticles, and Ascorbate with No Electron Relay: Participation of Good's Buffers.

PubMed

Clark, Emily R; Kurtz, Donald M

2017-04-17

Development of efficient light-driven splitting of water, 2H 2 O → 2H 2 + O 2 , often attempts to optimize photosensitization of the reductive and oxidative half-reactions individually. Numerous homogeneous and heterogeneous systems have been developed for photochemical stimulation of the reductive half reaction, 2H + + 2e - → H 2 . These systems generally consist of various combinations of a H + reduction catalyst, a photosensitizer (PS), and a "sacrificial" electron donor. Zinc(II)-porphyrins (ZnPs) have frequently been used as PSs for H 2 generation, but they are subject to various self-quenching processes in aqueous solutions. Colloidal platinum in nanoparticle form (Pt NP) is a classical H + reduction catalyst using ZnP photosensitizers, but efficient photosensitized H 2 generation requires an electron relay molecule between ZnP and Pt NP. The present report describes an aqueous system for visible (white) light-sensitized generation of H 2 using a protein-embedded Zn(II)-protoporphyrin IX as PS and Pt NP as H + reduction catalyst without an added electron relay. This system operated efficiently in piperazino- and morpholino-alkylsulfonic acid (Good's buffers), which served as sacrificial electron donors. The system also required ascorbate at relatively modest concentrations, which stabilized the Zn(II)-protoporphyrin IX against photodegradation. In the absence of an electron relay molecule, the photosensitized H 2 generation must involve formation of at least a transient complex between a protein-embedded Zn(II)-protoporphyrin IX species and Pt NP.

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, Travis A.; Witt, Suzanne E.; Li, Zhanyong

Formamidinate-bridged Rh 2 II,II complexes containing diimine ligands of the formula cis-[Rh 2 II,II(μ-DTolF) 2(NN) 2] 2+ (Rh 2-NN 2), where DTolF = p-ditolylformamidinate and NN = dppn (benzo[i]dipyrido[3,2-a:2',3'-h]quinoxaline), dppz (dipyrido[3,2-a:2',3'-c]phenazine), and phen (1,10-phenanthroline), electrocatalytically reduce H + to H 2 in DMF solutions containing CH 3COOH at a glassy carbon electrode. Cathodic scans in the absence of acid display a Rh III,II/II,II reduction at -0.90 V vs Fc +/Fc followed by NN 0/– reduction at -1.13, -1.36, and -1.65 V for Rh 2-dppn 2, Rh 2-dppz 2, and Rh 2-phen 2, respectively. Upon the addition of acid, Rh 2-dppnmore » 2 and Rh 2-dppz 2 undergo reduction–protonation–reduction at each pyrazine-containing NN ligand prior to the Rh 2 II,II/II,I reduction. The Rh 2 II,I species is thus protonated at one of the metal centers, resulting in the formation of the corresponding Rh 2 II,III-hydride. In the case of Rh 2-phen 2, the reduction of the phen ligand is followed by intramolecular electron transfer to the Rh 2 II,II core in the presence of protons to form a Rh 2 II,III-hydride species. Further reduction and protonation at the Rh 2 core for all three complexes rapidly catalyzes H 2 formation with varied calculated turnover frequencies (TOF) and overpotential values (η): 2.6 × 10 4 s –1 and 0.56 V for Rh 2-dppn, 2.8 × 10 4 s –1 and 0.50 V for Rh 2-dppz 2, and 5.9 × 10 4 s –1 and 0.64 V for Rh 2-phen 2. Bulk electrolysis confirmed H 2 formation, and further CH 3COOH addition regenerates H 2 production, attesting to the robust nature of the architecture. The cis-[Rh 2 II,II(μ-DTolF) 2(NN) 2] 2+ architecture benefits by combining electron-rich formamidinate bridges, a redox-active Rh 2 II,II core, and electron-accepting NN diimine ligands to allow for the electrocatalysis of H + substrate to H 2 fuel.« less

Electron Spin Resonance Studies of Carbonic Anhydrase: Transition Metal Ions and Spin-Labeled Sulfonamides*

PubMed Central

Taylor, June S.; Mushak, Paul; Coleman, Joseph E.

1970-01-01

Electron spin resonance (esr) spectra of Cu(II) and Co(II) carbonic anhydrase, and a spin-labeled sulfonamide complex of the Zn(II) enzyme, are reported. The coordination geometry of Cu(II) bound in the enzyme appears to have approximately axial symmetry. Esr spectra of enzyme complexes with metal-binding anions also show axial symmetry and greater covalency, in the order ethoxzolamide < SH- < N3- ≤ CN-. Well-resolved superhyperfine structure in the spectrum of the cyanide complex suggests the presence of two, and probably three, equivalent nitrogen ligands from the protein. Esr spectra of the Co(II) enzyme and its complexes show two types of Co(II) environment, one typical of the native enzyme and the 1:1 CN- complex, and one typical of a 2:1 CN- complex. Co(II) in the 2:1 complex appears to be low-spin and probably has a coordination number of 5. Binding of a spin-labeled sulfonamide to the active center immobilizes the free radical. The similarity of the esr spectra of spin-labeled Zn(II) and Co(II) carbonic anhydrases suggests that the conformation at the active center is similar in the two metal derivatives. PMID:4320976

Phenol oxidation through its adduct formation with chromium complex of 1,4,8,11-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane: A theoretical study

NASA Astrophysics Data System (ADS)

Narayanan, Jayanthi; Guadalupe, Hernández J.; Thangarasu, Pandiyan

2017-04-01

Structural and electronic properties of [cis-[Cr(tmpcH)X2]n+ (n = 2 or 4; X = OH-, Cl-, Br- and H2O; tmpcH = 1,4,8,11-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane were analyzed by DFT and TD-DFT methods. The local reactivity active site of the ligand was determined by the condensed-to atom Fukui indexes (CAFI) f(r). In the study, the axial bond distance with metal ion undergoes a considerable change from shorter to longer as OH < Cl- < Br- < H2O, agreeing with the molecular orbital analysis where the dz2 energy is lowered for OH- compared to H2O at the axial position. After analyzing the geometrical data collected from literature for the complexes of Cr(II), Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn (II) with tmpcH, it was found that the bond distance decreases with increasing number of d-electrons in the 3d orbital, suggesting that the over-lapping of oribital (π) from Npy with the metal d-orbital is more effective than those from Ncyclam with metal d-orbital. Therefore, the change of different oxidation states for [cis-[Cr(tmpcH)X2]n+ influences significantly the geometrical and electronic parameters. For cis-[Cr(tmpcH)Cl2]2+ the calculated bands are red shifted except for the lower energy band (595 nm) which agrees qualitatively with the experimental one; in addition, the effect of solvent on the electronic transition was analyzed. Furthermore, we collected the electronic data for several chromium complexes from the literature, and compared with our results by plotting the data against number of chromium compounds. Finally, the phenol oxidation properties of the chromium complexes were studied, and phenol forms an adduct with [Cr(tmpcH)Cl]3+ to yield [Cr(tmpcH)Cl-OPh]2+ which could produce the phenol radical, which is enhanced by the presence of -OCH3 group at para- position in the phenolic ring.

19 CFR 210.8 - Commencement of preinstitution proceedings.

Code of Federal Regulations, 2012 CFR

2012-04-01

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19 CFR 210.8 - Commencement of preinstitution proceedings.

Code of Federal Regulations, 2013 CFR

2013-04-01

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19 CFR 210.8 - Commencement of preinstitution proceedings.

Code of Federal Regulations, 2014 CFR

2014-04-01

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21 CFR 1305.28 - Canceling and voiding electronic orders.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 9 2014-04-01 2014-04-01 false Canceling and voiding electronic orders. 1305.28... I AND II CONTROLLED SUBSTANCES Electronic Orders § 1305.28 Canceling and voiding electronic orders. (a) A supplier may void all or part of an electronic order by notifying the purchaser of the voiding...

21 CFR 1305.28 - Canceling and voiding electronic orders.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Canceling and voiding electronic orders. 1305.28... I AND II CONTROLLED SUBSTANCES Electronic Orders § 1305.28 Canceling and voiding electronic orders. (a) A supplier may void all or part of an electronic order by notifying the purchaser of the voiding...

21 CFR 1305.25 - Unaccepted and defective electronic orders.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Unaccepted and defective electronic orders. 1305... SCHEDULE I AND II CONTROLLED SUBSTANCES Electronic Orders § 1305.25 Unaccepted and defective electronic orders. (a) No electronic order may be filled if: (1) The required data fields have not been completed...

21 CFR 1305.25 - Unaccepted and defective electronic orders.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 9 2014-04-01 2014-04-01 false Unaccepted and defective electronic orders. 1305... SCHEDULE I AND II CONTROLLED SUBSTANCES Electronic Orders § 1305.25 Unaccepted and defective electronic orders. (a) No electronic order may be filled if: (1) The required data fields have not been completed...

Probing the electronic structure of platinum(II) chromophores: crystal structures, NMR structures, and photophysical properties of six new bis- and di- phenolate/thiolate Pt(II)diimine chromophores.

PubMed

Weinstein, Julia A; Tierney, Mark T; Davies, E Stephen; Base, Karel; Robeiro, Anthony A; Grinstaff, Mark W

2006-05-29

A general route for synthesis of six structurally similar Pt(II) diimine thiolate/phenolates chromophores possessing bulky phenolate or thiolate ligands is reported. The Pt chromophores were characterized using an array of techniques including 1H, 13C, and 195Pt NMR, absorption, emission, (spectro)electrochemistry, and EPR spectroscopy. Systematic variation of the electronic structure of the Pt(II) chromophores studied was achieved by (i) changing solvent polarity; (ii) substituting oxygen for sulfur in the donor ligand; (iii) alternating donor ligands from bis- to di-coordination; and (iv) changing the electron donating/withdrawing properties of the ligand(s). The lowest excited state in these new chromophores was assigned to a [charge-transfer-to-diimine] transition from the HOMO of mixed Pt/S (or Pt/O) character on the basis of absorption and emission spectroscopy, UV/vis (spectro)electrochemistry, and EPR spectroscopy. One of the chromophores, Pt(dpphen)(3,5-di-tert-butyl-catecholate) represents an example of a Pt(II) diimine phenolate chromophore that possesses a reversible oxidation centered predominantly on the donor ligand. Results from EPR spectroscopy indicate participation of the Pt(II) orbitals in the HOMO. There is a dramatic difference in the photophysical properties of carborane complexes compared to other mixed-ligand Pt(II) compounds, which includes room-temperature emission and photostability. The charge-transfer character of the lowest excited state in this series of chromophores is maintained throughout. Moreover, the absorption and emission energies and the redox properties of the excited state can be significantly tuned.

Binding of manganese(II) to a tertiary stabilized hammerhead ribozyme as studied by electron paramagnetic resonance spectroscopy

PubMed Central

KISSELEVA, NATALIA; KHVOROVA, ANASTASIA; WESTHOF, ERIC; SCHIEMANN, OLAV

2005-01-01

Electron paramagnetic resonance (EPR) spectroscopy is used to study the binding of MnII ions to a tertiary stabilized hammer-head ribozyme (tsHHRz) and to compare it with the binding to the minimal hammerhead ribozyme (mHHRz). Continuous wave EPR measurements show that the tsHHRz possesses a single high-affinity MnII binding site with a KD of ≤10 nM at an NaCl concentration of 0.1 M. This dissociation constant is at least two orders of magnitude smaller than the KD determined previously for the single high-affinity MnII site in the mHHRz. In addition, whereas the high-affinity MnII is displaced from the mHHRz upon binding of the aminoglycoside antibiotic neomycin B, it is not from the tsHHRz. Despite these pronounced differences in binding, a comparison between the electron spin echo envelope modulation and hyperfine sublevel correlation spectra of the minimal and tertiary stabilized HHRz demonstrates that the structure of both binding sites is very similar. This suggests that the MnII is located in both ribozymes between the bases A9 and G10.1 of the sheared G · A tandem base pair, as shown previously and in detail for the mHHRz. Thus, the much stronger MnII binding in the tsHHRz is attributed to the interaction between the two external loops, which locks in the RNA fold, trapping the MnII in the tightly bound conformation, whereas the absence of long-range loop–loop interactions in the mHHRz leads to more dynamical and open conformations, decreasing MnII binding. PMID:15611296